# 11 - PART 4 Oncology and Hematology # 01 - SECTION 1 Neoplastic Disorders ## SECTION 1 Neoplastic Disorders Section 1 Neoplastic Disorders Dan L. Longo Approach to the Patient with Cancer The application of current treatment techniques (surgery, radiation therapy, chemotherapy, and biologic therapy) results in the cure of nearly two of three patients diagnosed with cancer. Nevertheless, patients experience the diagnosis of cancer as one of the most trau­ matic and revolutionary events that has ever happened to them. Inde­ pendent of prognosis, the diagnosis brings with it a change in a person’s self-image and in their role in the home and workplace. The prognosis of a person who has just been found to have pancreatic cancer is the same as the prognosis of the person with aortic stenosis who develops the first symptoms of congestive heart failure (median survival, ~8 months). However, the patient with heart disease may remain functional and maintain a self-image as a fully intact person with just a malfunctioning part, a diseased organ (“a bum ticker”). By contrast, the patient with pancreatic cancer has a completely altered self-image and is viewed differently by family and anyone who knows the diagnosis. The patient is being attacked and invaded by a disease that could be anywhere in the body. Every ache or pain takes on TABLE 73-1  Distribution of Cancer Incidence and Deaths for 2021 MALE FEMALE SITES % NUMBER SITES % NUMBER Cancer Incidence Prostate 299,010 Breast 310,720 Lung 116,310 Lung 118,270 Colorectal 81,540 Colorectal 71,270 Bladder 63,070 Endometrial 67,880 Melanoma 59,170 Melanoma 41,470 Kidney 52,380 Lymphoma 36,030 Lymphoma 44,590 Pancreas 31,910 Oral cavity 41,510 Thyroid 31,520 Leukemia 36,450 Kidney 29,230 Pancreas 34,530 Leukemia 26,320 All others 200,520 All others 207,440 All sites 1,029,080 All sites 972,060 Cancer Deaths Lung 65,790 Lung 59,280 Prostate 35,250 Breast 42,250 Colorectal 28,700 Pancreas 24,480 Pancreas 25,270 Colorectal 24,310 Liver 19,120 Endometrial 13.250 Leukemia 13,640 Ovary 12,740 Esophagus 12,880 Liver 10,720 Bladder 12,290 Leukemia 10,030 Lymphoma 11,780 Lymphoma 8,360 CNS 10,690 CNS 8,070 All others 87,390 All others 75,4330 All sites 322,800 All sites 288,920 Source: From RL Siegel et al: Cancer statistics, 2024. CA Cancer J Clin 74:12, 2024. Reproduced John Wiley & Sons Ltd. Oncology and Hematology PART 4 desperate significance. Cancer is an exception to the coordinated interaction among cells and organs. In general, the cells of a multicel­ lular organism are programmed for collaboration. Many diseases occur because the specialized cells fail to perform their assigned task. Cancer takes this malfunction one step further. Not only is there a failure of the cancer cell to maintain its specialized function, but it also strikes out on its own; the cancer cell competes to survive using natural mutability and natural selection to seek advantage over normal cells in a reca­ pitulation of evolution. One consequence of the traitorous behavior of cancer cells is that the patient feels betrayed by their body. The cancer patient feels that they, and not just a body part, are diseased. THE MAGNITUDE OF THE PROBLEM No nationwide cancer registry exists; therefore, the incidence of cancer is estimated on the basis of the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) database, which tabulates cancer incidence and death figures from 13 sites, accounting for about 10% of the U.S. population, and from population data from the U.S. Census Bureau. In 2024, 2.001 million new cases of invasive cancer (1,029,080 men and 927,060 women) were diagnosed, and 611,720 per­ sons (322,800 men and 288,920 women) died from cancer. The percent distribution of new cancer cases and cancer deaths by site for men and women is shown in Table 73-1. Cancer mortality continues to decline; however, 6 of the 10 most common cancers have increased in incidence by 1–3% in recent years, and troubling disparities among different racial/ethnic groups persist. Mortality is twice as high in black people than white people for cancers of the prostate, stomach, and uterine corpus. Cancer is the cause of one in four deaths in the United States. # 02 - 73 Approach to the Patient with Cancer ### 73 Approach to the Patient with Cancer Section 1 Neoplastic Disorders Dan L. Longo Approach to the Patient with Cancer The application of current treatment techniques (surgery, radiation therapy, chemotherapy, and biologic therapy) results in the cure of nearly two of three patients diagnosed with cancer. Nevertheless, patients experience the diagnosis of cancer as one of the most trau­ matic and revolutionary events that has ever happened to them. Inde­ pendent of prognosis, the diagnosis brings with it a change in a person’s self-image and in their role in the home and workplace. The prognosis of a person who has just been found to have pancreatic cancer is the same as the prognosis of the person with aortic stenosis who develops the first symptoms of congestive heart failure (median survival, ~8 months). However, the patient with heart disease may remain functional and maintain a self-image as a fully intact person with just a malfunctioning part, a diseased organ (“a bum ticker”). By contrast, the patient with pancreatic cancer has a completely altered self-image and is viewed differently by family and anyone who knows the diagnosis. The patient is being attacked and invaded by a disease that could be anywhere in the body. Every ache or pain takes on TABLE 73-1  Distribution of Cancer Incidence and Deaths for 2021 MALE FEMALE SITES % NUMBER SITES % NUMBER Cancer Incidence Prostate 299,010 Breast 310,720 Lung 116,310 Lung 118,270 Colorectal 81,540 Colorectal 71,270 Bladder 63,070 Endometrial 67,880 Melanoma 59,170 Melanoma 41,470 Kidney 52,380 Lymphoma 36,030 Lymphoma 44,590 Pancreas 31,910 Oral cavity 41,510 Thyroid 31,520 Leukemia 36,450 Kidney 29,230 Pancreas 34,530 Leukemia 26,320 All others 200,520 All others 207,440 All sites 1,029,080 All sites 972,060 Cancer Deaths Lung 65,790 Lung 59,280 Prostate 35,250 Breast 42,250 Colorectal 28,700 Pancreas 24,480 Pancreas 25,270 Colorectal 24,310 Liver 19,120 Endometrial 13.250 Leukemia 13,640 Ovary 12,740 Esophagus 12,880 Liver 10,720 Bladder 12,290 Leukemia 10,030 Lymphoma 11,780 Lymphoma 8,360 CNS 10,690 CNS 8,070 All others 87,390 All others 75,4330 All sites 322,800 All sites 288,920 Source: From RL Siegel et al: Cancer statistics, 2024. CA Cancer J Clin 74:12, 2024. Reproduced John Wiley & Sons Ltd. Oncology and Hematology PART 4 desperate significance. Cancer is an exception to the coordinated interaction among cells and organs. In general, the cells of a multicel­ lular organism are programmed for collaboration. Many diseases occur because the specialized cells fail to perform their assigned task. Cancer takes this malfunction one step further. Not only is there a failure of the cancer cell to maintain its specialized function, but it also strikes out on its own; the cancer cell competes to survive using natural mutability and natural selection to seek advantage over normal cells in a reca­ pitulation of evolution. One consequence of the traitorous behavior of cancer cells is that the patient feels betrayed by their body. The cancer patient feels that they, and not just a body part, are diseased. THE MAGNITUDE OF THE PROBLEM No nationwide cancer registry exists; therefore, the incidence of cancer is estimated on the basis of the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) database, which tabulates cancer incidence and death figures from 13 sites, accounting for about 10% of the U.S. population, and from population data from the U.S. Census Bureau. In 2024, 2.001 million new cases of invasive cancer (1,029,080 men and 927,060 women) were diagnosed, and 611,720 per­ sons (322,800 men and 288,920 women) died from cancer. The percent distribution of new cancer cases and cancer deaths by site for men and women is shown in Table 73-1. Cancer mortality continues to decline; however, 6 of the 10 most common cancers have increased in incidence by 1–3% in recent years, and troubling disparities among different racial/ethnic groups persist. Mortality is twice as high in black people than white people for cancers of the prostate, stomach, and uterine corpus. Cancer is the cause of one in four deaths in the United States. Male Prostate Rate per 100,000 population Lung & bronchus Colorectum Urinary bladder PART 4 Oncology and Hematology Thyroid Livera Melanoma of the skin 1975 1980 1985 1990 1995 2000 Year of diagnosis 2005 2010 2015 2020 FIGURE 73-1  Trends in cancer incidence for men and women, 1975–2020. Incidence data for 2020 are indicated by color dots separate from the trend lines. (Reproduced with permission from RL Siegel et al: Cancer statistics, 2024. CA Cancer J Clin 74:1, 2024.) The most significant risk factor for cancer overall is age; 58% of all cases were in those aged >65 years, down from 61% in 1995, despite an increase in this age group from 13% to 17% of the population. Cancer incidence increases as the third, fourth, or fifth power of age in differ­ ent sites. For the interval between birth and age 49 years, 1 in 29 men and 1 in 19 women will develop cancer; for the interval between ages 50 and 59 years, 1 in 15 men and 1 in 17 women will develop cancer; for the interval between ages 60 and 69 years, 1 in 6 men and 1 in 10 women will develop cancer; and for people aged ≥70, 1 in 3 men and 1 in 4 women will develop cancer. Overall, men have a 40.5% risk of developing cancer at some time during their lives; women have a 38.9% lifetime risk. Cancer is the second leading cause of death behind heart disease. Deaths from heart disease have declined 45% in the United States since 1950 and continue to decline. Cancer has overtaken heart disease as the number one cause of death in persons aged <85 years. Incidence trends over time are shown in Fig. 73-1. After a 70-year period of increase, cancer deaths began to decline in 1990–1991 (Fig. 73-2). Between 1990 and 2010, cancer deaths decreased by 21% among men and 12.3% among women. The incidence has been steady since 2013. The magni­ tude of the decline is illustrated in Fig. 73-3. The five leading causes of cancer deaths are shown for various populations in Table 73-2. The 5-year survival for white patients was 39% in 1960–1963 and 68% in 2010–2016. Cancers are more often deadly in blacks; the 5-year survival was 63% for the 2010–2016 interval; however, the racial dif­ ferences are narrowing over time. Incidence and mortality vary among racial and ethnic groups (Table 73-3). The basis for these differences is unclear. Advances in cancer prevention, diagnosis, and treatment since the early 1990s have averted millions of cancer deaths based on projec­ tions from the slopes of the mortality curves leading up to the 1990s (Fig. 73-4). ■ ■CANCER AROUND THE WORLD In 2022, nearly 20 million new cancer cases and 9.7 million can­ cer deaths were estimated worldwide, according to estimates of GLOBOCAN 2022, developed by the International Agency for Research on Cancer (IARC). Rates are increasing worldwide. When Female Breast Lung & bronchus Colorectum Uterine corpus Thyroid Livera Melanoma of the skin 1975 1980 1985 1990 1995 2000 Year of diagnosis 2005 2010 2015 2020 broken down by region of the world, almost half of cases were in Asia (which has 59.2% of the world’s population), 26% in Europe (9.6% of the world’s population), 13.1% in North America, 7.1% in Central/ South America (the Americas, North and South, account for 13.3% of the world’s population), 6% in Africa (16.6% of the world’s population), and 1% in Australia/New Zealand (0.5% of the world’s population) (Fig. 73-5). Lung cancer is the most common cancer and the most common cause of cancer death in the world. Its incidence is highly variable, affecting only 2 per 100,000 African women but as many as 61 per 100,000 North American men. Breast cancer is the second most common cancer worldwide; however, it ranks fourth as a cause of death behind lung, stomach, and liver cancer. Among the eight most common forms of cancer, lung (2-fold), breast (3-fold), prostate (2.5-fold), and colorectal (3-fold) cancers are more common in more developed countries than in less developed countries. By contrast, liver (2-fold), cervical (2-fold), and esophageal (2- to 3-fold) cancers are more common in less developed countries. Stomach cancer incidence is simi­ lar in more and less developed countries but is much more common in Asia than North America or Africa. The most common cancers in Africa are cervical, breast, and liver cancers. It has been estimated that nine modifiable risk factors are responsible for more than one-third of cancers worldwide. These include smoking, alcohol consumption, obesity, physical inactivity, low fruit and vegetable consumption, unsafe sex, air pollution, indoor smoke from household fuels, and contaminated injections. PATIENT MANAGEMENT Important information is obtained from every portion of the routine history and physical examination. The duration of symptoms may reveal the chronicity of disease. The past medical history may alert the physician to the presence of underlying diseases that may affect the choice of therapy or the side effects of treatment. The social history may reveal occupational exposure to carcinogens or habits, such as smoking or alcohol consumption, that may influence the course of dis­ ease and its treatment. The family history may suggest an underlying familial cancer predisposition and point out the need to begin surveil­ lance or other preventive therapy for unaffected siblings of the patient. The review of systems may suggest early symptoms of metastatic dis­ ease or a paraneoplastic syndrome. All sites combined Deaths per 100,000 population Males, by site Stomach Colorectum Liver & intrahepatic bile duct Pancreas Lung & bronchus Prostate Leukemia Deaths per 100,000 males Females, by site Stomach Colorectum Liver & intrahepatic bile duct Pancreas Lung & bronchus Breast Uterus (corpus and cervix combined) Deaths per 100,000 females Year of death FIGURE 73-2  Trends in cancer mortality rates in men and women, 1930–2021. (Reproduced with permission from RL Siegel et al: Cancer statistics, 2024. CA Cancer J Clin 74:1, 2024.) ■ ■DIAGNOSIS The diagnosis of cancer relies most heavily on invasive tissue biopsy and should never be made without obtaining tissue; no noninvasive diagnostic test is sufficient to define a disease process such as cancer (one exception to this rule may be hepatocellular carcinoma, which may be reliably diagnosed based on computed tomography [CT] or magnetic resonance imaging [MRI] showing the characteristic dynamic perfusion pattern of arterial hyperenhancement and venous or delayed phase washout). Although in rare clinical settings (e.g., thy­ roid nodules), fine-needle aspiration is an acceptable diagnostic proce­ dure, the diagnosis generally depends on obtaining adequate tissue to permit careful evaluation of the histology of the tumor, its grade, and its invasiveness and to yield further molecular diagnostic information, such as the expression of cell-surface markers or intracellular proteins that typify a particular cancer, or the presence of a molecular marker, such as the t(8;14) translocation of Burkitt’s lymphoma. Increasing evidence links the expression of certain genes with the prognosis and response to therapy (Chaps. 76 and 77). Occasionally, a patient will present with a metastatic disease process that is defined as cancer on biopsy but has no apparent primary site of disease. Efforts should be made to define the pri­ mary site based on age, sex, sites of involvement, histology and tumor markers, and personal and family history. Particular attention should be focused on ruling out the most treatable causes (Chap. 97). Male Once the diagnosis of cancer is made, the management of the patient is best undertaken as a multidisciplinary collaboration among the primary care physician, medical oncologists, sur­ gical oncologists, radiation oncologists, oncology nurse specialists, pharmacists, social workers, rehabilitation medicine specialists, and a number of other consulting professionals working closely with each other and with the patient and family. Female ■ ■DEFINING THE EXTENT OF DISEASE AND THE PROGNOSIS The first priority in patient management after the diagnosis of cancer is established and shared with the patient is to determine the extent of disease. The curability of a tumor usually is inversely pro­ portional to the tumor burden. Ideally, the tumor will be diagnosed before symptoms develop or as a consequence of screening efforts (Chap. 75). A very high proportion of such patients can be cured. However, most patients with cancer pres­ ent with symptoms related to the cancer, caused either by mass effects of the tumor or by altera­ tions associated with the production of cytokines or hormones by the tumor. CHAPTER 73 Approach to the Patient with Cancer For most cancers, the extent of disease is evaluated by a variety of noninvasive and inva­ sive diagnostic tests and procedures. This process is called staging. There are two types. Clinical staging is based on physical examination, radio­ graphs, isotopic scans, CT scans, and other imaging procedures; pathologic staging takes into account information obtained during a surgical procedure, which might include intraoperative palpation, resection of regional lymph nodes and/or tissue adjacent to the tumor, and inspec­ tion and biopsy of organs commonly involved in disease spread. Pathologic staging includes histologic examination of all tissues removed during the surgical procedure. Surgical proce­ dures performed may include a simple lymph node biopsy or more extensive procedures such as thoracotomy, mediastinoscopy, or laparotomy. Surgical staging may occur in a separate procedure or may be done at the time of definitive surgical resection of the primary tumor. A subset of pathologic staging is the examination of tissue obtained at initial surgery that occurs after the delivery of some treatment, which is called neoadjuvant therapy. Stage of disease determined after neoadjuvant therapy is designated with the prefix y. Knowledge of the predilection of particular tumors for spreading to adjacent or distant organs helps direct the staging evaluation. Information obtained from staging is used to define the extent of disease as localized, as exhibiting spread outside of the organ of origin to regional but not distant sites, or as metastatic to distant sites. The most widely used system of staging is the tumor, node, metastasis (TNM) system codified by the International Union Against Cancer and the American Joint Committee on Cancer. The TNM classification is an anatomically based system that categorizes the tumor on the basis of the size of the primary tumor lesion (T1–4, where a higher number indicates a tumor of larger size), the presence of nodal involvement (usually N0 and N1 for the absence and presence, respectively, of involved nodes, although some tumors have more elaborate systems of nodal grading), and the presence of metastatic disease (M0 and M1 Male Rate per 100,000 Lung & bronchus Colorectum Leukemia Brain & other nervous system 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020 7,000 PART 4 Oncology and Hematology 6,000 5,000 Lung & bronchus Number of deaths 4,000 3,000 Colorectum Leukemia 2,000 1,000 Brain & other nervous system 1975 1980 1985 1990 1995 2000 Year of death 2005 2010 2015 2020 FIGURE 73-3  Trends in cancer incidence and death rates. (Reproduced with permission from RL Siegel et al: Cancer statistics, 2024. CA Cancer J Clin 74:1, 2024.) TABLE 73-2  The Five Leading Primary Tumor Sites for Patients Dying of Cancer Based on Age and Sex in 2018 RANK SEX ALL AGES UNDER 20 20–39 40–49 50-64 65–79 >80 M Lung CNS Colorectal Colorectal Lung Lung Lung F Lung CNS Breast Breast Lung Lung Lung M Prostate Leukemia CNS Lung Colorectal Prostate Prostate F Breast Leukemia Cervix Colorectal Breast Breast Breast M Colorectal Bone sarcoma Leukemia CNS Pancreas Liver Colorectal F Colorectal Soft tissue sarcoma Colorectal Lung Colorectal Pancreas Colorectal M Pancreas Soft tissue sarcoma Testis Pancreas Liver Colorectal Bladder F Pancreas Bone sarcoma CNS Cervix Pancreas Colorectal Pancreas M Liver Lymphoma Lymphoma Esophagus Esophagus Liver Pancreas F Ovary Kidney Leukemia Ovary Ovary Ovary Leukemia Abbreviations: CNS, central nervous system; F, female; M, male. Source: From RL Siegel et al: Cancer statistics, 2024. CA Cancer J Clin 74:12, 2024. Female Breast Lung & bronchus Colorectum Uterine cervix 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020 Breast Lung & bronchus Colorectum Uterine cervix 1975 1980 1985 1990 1995 2000 Year of death 2005 2010 2015 2020 AGE, YEARS TABLE 73-3  Cancer Incidence and Mortality in Racial and Ethnic Groups, United States, 2016–2020 SITE SEX WHITE BLACK Incidence per 100,000 Population All M 511.2 533.9 299.0 504.1 377.2 F 499.3 409.9 307.3 465.5 351.3 Breast 134.9 129.6 104.6 115.5 100.7 Colorectal M 40.4 48.8 33.4 57.8 38.2 F 30.5 35.0 23.7 43.7 27.2 Kidney M 24.3 26.4 11.6 43.9 23.5 F 12.1 13.7 5.5 23.9 13.3 Liver M 11.2 17.0 18.4 27.3 20.4 F 4.2 5.5 6.7 12.3 8.4 Lung M 765.7 72,4 40.8 67.2 34.3 F 54.8 45.8 28.1 58.6 24.0 Prostate 110.7 186.1 60.9 91.9 90.9 Stomach M 7.1 13.0 11.8 13.1 11.4 F 3.4 7.4 6.9 7.8 7.7 Cervix 7.2 8.6 6.0 11.4 9.7 Endometrial 27.9 28.9 21.7 30.4 25.8 Deaths per 100,000 Population All M 183.3 217.4 111.6 221.6 130.2 F 133.6 150.2 83.7 157.9 93.5 Breast 19.7 27.8 11.8 21.1 13.7 Colorectal M 15.5 22.4 11.0 23.1 13.6 F 11.1 14.4 7.8 16.0 8.5 Kidney M 5.3 5.2 2.4 9.9 4.8 F 2.3 2.2 1.0 4.2 2.1 Liver M 8.5 13.0 12.6 19.9 13.1 F 3.7 4.8 5.2 8.8 6.0 Lung M 44.9 51.3 25.9 52.3 21.- F 32.9 28.0 15.6 37.0 11.4 Prostate 17.9 37.9 8.7 22.5 15.4 Stomach M 2.9 7.2 6.0 7.7 5.9 F 1.5 3.5 3.7 4.1 3.9 Cervix 2.0 3.3 1.7 2.3 2.5 Endometrial 4.6 9.1 3.5 4.9 4.3 aBased on Indian Health Service delivery areas. Abbreviations: F, female; M, male. Source: From RL Siegel et al: Cancer statistics, 2024. CA Cancer J Clin 74:12, 2024. Reproduced of John Wiley & Sons Ltd. for the absence and presence, respectively, of metastases). The various permutations of T, N, and M scores (sometimes including tumor histo­ logic grade [G]) are then broken into stages, usually designated by the roman numerals I through IV. Tumor burden increases and curability decreases with increasing stage. Other anatomic staging systems are used for some tumors, e.g., the Dukes classification for colorectal can­ cers, the International Federation of Gynecologists and Obstetricians classification for gynecologic cancers, and the Ann Arbor classification for Hodgkin’s lymphoma. Certain tumors cannot be grouped on the basis of anatomic con­ siderations. For example, hematopoietic tumors such as leukemia, myeloma, and lymphoma are often disseminated at presentation and do not spread like solid tumors. For these tumors, other prognostic factors have been identified (Chaps. 109–116). In addition to tumor burden, a second major determinant of treatment outcome is the physiologic reserve of the patient. Patients who are bedridden before developing cancer are likely to fare worse, stage for stage, than fully active patients. Physiologic reserve is a determinant of how a patient is likely to cope with the physiologic stresses imposed by the cancer and its treatment. This factor is dif­ ficult to assess directly. Instead, surrogate markers for physiologic ASIAN/PACIFIC ISLANDER AMERICAN INDIANa HISPANIC CHAPTER 73 Approach to the Patient with Cancer reserve are used, such as the patient’s age or Karnofsky performance status (Table 73-4) or Eastern Cooperative Oncology Group (ECOG) performance status (Table 73-5). Older patients and those with a Karnofsky performance status <70 or ECOG performance status ≥3 have a poor prognosis unless the poor performance is a reversible consequence of the tumor. Some have advocated for using one of the geriatric assessment tools to gauge physiologic reserve. See ASCO’s video for an example of a geriatric assessment tool (https://www. youtube.com/watch?v=jnaQIjOz2Dw). Increasingly, biologic features of the tumor are being related to prognosis. The expression of particular oncogenes, drug-resistance genes, apoptosis-related genes, and genes involved in metastasis is being found to influence response to therapy and prognosis. The presence of selected cytogenetic abnormalities may influence sur­ vival. Tumors with higher growth fractions, as assessed by expression of proliferation-related markers such as proliferating cell nuclear antigen (detectable by staining with Ki67 antibody), behave more aggressively than tumors with lower growth fractions. Information obtained from studying the tumor itself will increasingly be used to influence treatment decisions. Host genes involved in drug metabo­ lism can influence the safety and efficacy of particular treatments. Male Female 550,000 500,000 450,000 400,000 350,000 Number of deaths 300,000 2,794,900 cancer deaths averted 250,000 200,000 150,000 PART 4 Oncology and Hematology 100,000 50,000 Year of death FIGURE 73-4  Cancer deaths averted in men and women since the early 1990s. Projections based on death continuing on the established trajectory. (Reproduced with permission from RL Siegel et al: Cancer statistics, 2024. CA Cancer J Clin 74:1, 2024.) Enormous heterogeneity has been noted by studying tumors; we have learned that morphology is not capable of discerning certain distinct subsets of patients whose tumors have different sets of abnor­ malities. Tumors that look the same by light microscopy can be very different. Similarly, tumors that look quite different from one another histologically can share genetic lesions that predict responses to treat­ ments. Furthermore, tumor cells vary enormously within a single patient even though the cells share a common origin. ■ ■MAKING A TREATMENT PLAN From information on the extent of disease and the prognosis and in conjunction with the patient’s wishes, it is determined whether the treatment approach should be curative or palliative in intent. Coop­ eration among the various professionals involved in cancer treatment is of the utmost importance in treatment planning. For some cancers, chemotherapy or chemotherapy plus radiation therapy delivered before the use of definitive surgical treatment (so-called neoadju­ vant therapy) may improve the outcome, as seems to be the case for locally advanced breast cancer, head and neck cancers, and lung can­ cers, among others. In certain settings in which combined-modality therapy is intended, coordination among the medical oncologist, radiation oncologist, and surgeon is crucial to achieving optimal results. Sometimes the chemotherapy and radiation therapy need to be delivered sequentially and other times concurrently. Surgical pro­ cedures may precede or follow other treatment approaches. It is best for the treatment plan either to follow a standard protocol precisely or else to be part of an ongoing clinical research protocol evaluating new treatments. Ad hoc modifications of standard protocols are likely to compromise treatment results. The choice of treatment approaches was formerly dominated by the local culture in both the university and the practice settings. However, it is now possible to gain access electronically to standard treatment 550,000 500,000 450,000 400,000 350,000 300,000 250,000 1,344,600 cancer deaths averted 200,000 150,000 100,000 50,000 Year of death protocols and to every approved clinical research study in North America through a personal computer interface with the Internet.1 The skilled physician also has much to offer the patient for whom curative therapy is no longer an option. Often a combination of guilt and frustration over the inability to cure the patient and the pressure of a busy schedule greatly limit the time a physician spends with a patient who is receiving only palliative care. Resist these forces. In addition to the medi­ cines administered to alleviate symptoms (see below), it is important to remember the comfort that is provided by holding the patient’s hand, continuing regular examinations, and taking time to talk. ■ ■MANAGEMENT OF DISEASE AND TREATMENT COMPLICATIONS Although medicine has been guided through centuries by the aphorism “primum non nocere,” first do no harm, it fits modern medicine poorly. As a practical matter, nearly everything we do in patient care has risk of doing harm; diagnostic tests, therapeutic interventions, and even physical diagnosis can lead to patient harm. A more relevant guide to modern medicine is “primum succerrere”; first hasten to help. Because cancer therapies are toxic (Chap. 78), patient management involves addressing complications of both the disease and its treatment as well as the complex psychosocial problems associated with cancer. In the short term during a course of curative therapy, the patient’s functional 1The National Cancer Institute maintains a database called PDQ (Physician Data Query) that is accessible on the Internet under the name CancerNet at https://www.cancer.gov/publications/pdq. Information can be obtained through a facsimile machine using CancerFax by dialing 301-402-5874. Patient information is also provided by the National Cancer Institute in at least three formats: on the Internet via CancerNet at www.cancer.gov, through the CancerFax number listed above, or by calling 1-800-4-CANCER. The quality control for the information provided through these services is rigorous. Mortality, males Colorectum (5) Esophagus (3) Kaposi sarcoma (2) Lip, oral cavity (2) Lung (89) Prostate (52) Liver (24) Stomach (8) A Mortality, females Colorectum (4) Stomach (2) Esophagus (1) Breast (112) Cervix uteri (37) Lung (23) Liver (6) B FIGURE 73-5  Global maps showing most common cause of cancer mortality by country in 2022 among (A) men and (B) women. (Reproduced with permission from F Bray et al: Global cancer statistics 2022: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries. CA Cancer J Clin 74:229, 2024.) TABLE 73-4  Karnofsky Performance Index PERFORMANCE STATUS FUNCTIONAL CAPABILITY OF THE PATIENT Normal; no complaints; no evidence of disease Able to carry on normal activity; minor signs or symptoms of disease Normal activity with effort; some signs or symptoms of disease Cares for self; unable to carry on normal activity or do active work Requires occasional assistance but is able to care for most needs Requires considerable assistance and frequent medical care Disabled; requires special care and assistance Severely disabled; hospitalization is indicated, although death is not imminent Very sick; hospitalization is necessary; active supportive treatment is necessary Moribund, fatal processes progressing rapidly Dead CHAPTER 73 Approach to the Patient with Cancer status may decline. Treatment-induced toxicity is less acceptable if the goal of therapy is palliation. The most common side effects of treatment are nausea and vomiting (see below), febrile neutropenia (Chap. 79), and myelosuppression (Chap. 78). Tools are now available to minimize the acute toxicity of cancer treatment. TABLE 73-5  The Eastern Cooperative Oncology Group (ECOG) Performance Scale ECOG grade 0: Fully active, able to carry on all predisease performance without restriction ECOG grade 1: Restricted in physically strenuous activity but ambulatory and able to carry out work of a light or sedentary nature, e.g., light housework, office work ECOG grade 2: Ambulatory and capable of all self-care but unable to carry out any work activities. Up and about >50% of waking hours ECOG grade 3: Capable of only limited self-care, confined to bed or chair >50% of waking hours ECOG grade 4: Completely disabled. Cannot carry on any self-care. Totally confined to bed or chair ECOG grade 5: Dead Source: Reproduced with permission from MM Oken et al: Toxicity and response criteria of the Eastern Cooperative Oncology Group. Am J Clin Oncol 5:649, 1982. New symptoms developing in the course of cancer treatment should always be assumed to be reversible until proven otherwise. The fatal­ istic attribution of anorexia, weight loss, and jaundice to recurrent or progressive tumor could result in a patient dying from a reversible intercurrent cholecystitis. Intestinal obstruction may be due to revers­ ible adhesions rather than progressive tumor. Systemic infections, sometimes with unusual pathogens, may be a consequence of the immunosuppression associated with cancer therapy. Some drugs used to treat cancer or its complications (e.g., nausea) may produce central nervous system symptoms that look like metastatic disease or may mimic paraneoplastic syndromes such as the syndrome of inappropri­ ate antidiuretic hormone. A definitive diagnosis should be pursued and may even require a repeat biopsy. A critical component of cancer management is assessing the response to treatment. In addition to a careful physical examination in which all sites of disease are physically measured and recorded in a flow chart by date, response assessment usually requires periodic repeating of imaging tests that were abnormal at the time of staging. If imaging tests have become normal, repeat biopsy of previously involved tissue is performed to document complete response by patho­ logic criteria. Biopsies are not usually required if there is macroscopic residual disease. A complete response is defined as disappearance of all evidence of disease, and a partial response as >50% reduction in the sum of the products of the perpendicular diameters of all measurable lesions. The determination of partial response may also be based on a 30% decrease in the sums of the longest diameters of lesions (Response Evaluation Criteria in Solid Tumors [RECIST]). Progressive disease is defined as the appearance of any new lesion or an increase of >25% in the sum of the products of the perpendicular diameters of all measur­ able lesions (or an increase of 20% in the sums of the longest diameters by RECIST). Tumor shrinkage or growth that does not meet any of these criteria is considered stable disease. Some sites of involvement (e.g., bone) or patterns of involvement (e.g., lymphangitic lung or dif­ fuse pulmonary infiltrates) are considered unmeasurable. No response is complete without biopsy documentation of their resolution, but partial responses may exclude their assessment unless clear objective progression has occurred. PART 4 Oncology and Hematology For some hematologic neoplasms, flow cytometric and genetic assays may determine the presence of residual tumor cells that escape micro­ scopic detection. In general, these techniques can reliably detect as few as 1 tumor cell among 10,000 cells. If such tests do not detect tumor cells, the patient is said to have minimal residual disease negativity, a finding generally associated with more durable remissions. Accumulating data are defining interventions in patients with minimal residual disease positivity that can extend remission duration and survival. Tumor markers may be useful in patient management in certain tumors. Response to therapy may be difficult to gauge with certainty. However, some tumors produce or elicit the production of markers that can be measured in the serum or urine, and in a particular patient, rising and falling levels of the marker are usually associated with increasing or decreasing tumor burden, respectively. Some clinically useful tumor markers are shown in Table 73-6. Tumor markers are not in themselves specific enough to permit a diagnosis of malignancy to be made, but once a malignancy has been diagnosed and shown to be associated with elevated levels of a tumor marker, the marker can be used to assess response to treatment. The recognition and treatment of depression are important compo­ nents of management. The incidence of depression in cancer patients is ~25% overall and may be greater in patients with greater debility. This diagnosis is likely in a patient with a depressed mood (dysphoria) and/or a loss of interest in pleasure (anhedonia) for at least 2 weeks. In addition, three or more of the following symptoms are usually present: appetite change, sleep problems, psychomotor retardation or agitation, fatigue, feelings of guilt or worthlessness, inability to concentrate, and suicidal ideation. Patients with these symptoms should receive therapy. Medical therapy with a serotonin reuptake inhibitor such as fluoxetine (10–20 mg/d), sertraline (50–150 mg/d), or paroxetine (10–20 mg/d) or a tricyclic antidepressant such as amitriptyline (50–100 mg/d) or desipramine (75–150 mg/d) should be tried, allowing 4–6 weeks TABLE 73-6  Tumor Markers TUMOR MARKERS CANCER NONNEOPLASTIC CONDITIONS Hormones Human chorionic gonadotropin Gestational trophoblastic disease, gonadal germ cell tumor Pregnancy Calcitonin Medullary cancer of the thyroid Catecholamines Pheochromocytoma Oncofetal Antigens α Fetoprotein Hepatocellular carcinoma, gonadal germ cell tumor Cirrhosis, hepatitis Carcinoembryonic antigen Adenocarcinomas of the colon, pancreas, lung, breast, ovary Pancreatitis, hepatitis, inflammatory bowel disease, smoking Enzymes Prostatic acid phosphatase Prostate cancer Prostatitis, prostatic hypertrophy Neuron-specific enolase Small-cell cancer of the lung, neuroblastoma Lactate dehydrogenase Lymphoma, Ewing’s sarcoma Hepatitis, hemolytic anemia, many others Tumor-Associated Proteins Prostate-specific antigen Prostate cancer Prostatitis, prostatic hypertrophy Monoclonal immunoglobulin Myeloma Infection, MGUS CA-125 Ovarian cancer, some lymphomas Menstruation, peritonitis, pregnancy CA 19-9 Colon, pancreatic, breast cancer Pancreatitis, ulcerative colitis CD30 Hodgkin’s disease, anaplastic large-cell lymphoma — CD25 Hairy cell leukemia, adult T-cell leukemia/lymphoma Hemophagocytic lymphohistiocytosis Abbreviation: MGUS, monoclonal gammopathy of uncertain significance. for response. Effective therapy should be continued at least 6 months after resolution of symptoms. If therapy is unsuccessful, other classes of antidepressants may be used. In addition to medication, psychoso­ cial interventions such as support groups, psychotherapy, and guided imagery may be of benefit. Many patients opt for unproven or unsound approaches to treat­ ment when it appears that conventional medicine is unlikely to be curative. Those seeking such alternatives are often well educated and may be early in the course of their disease. Unsound approaches are usually hawked on the basis of unsubstantiated anecdotes and not only cannot help the patient but may be harmful. Physicians should strive to keep communications open and nonjudgmental, so that patients are more likely to discuss with the physician what they are actually doing. The appearance of unexpected toxicity may be an indication that a supplemental therapy is being taken.2 LONG-TERM FOLLOW-UP/LATE COMPLICATIONS At the completion of treatment, sites originally involved with tumor are reassessed, usually by radiography or imaging techniques, and any persistent abnormality is biopsied. If disease persists, the multidis­ ciplinary team discusses a new salvage treatment plan. If the patient has been rendered disease-free by the original treatment, the patient 2Information about unsound methods may be obtained from the National Council Against Health Fraud, Box 1276, Loma Linda, CA 92354, or from the Center for Medical Consumers and Health Care Information, 237 Thompson Street, New York, NY 10012. is followed regularly for disease recurrence. The optimal guidelines for follow-up care are not known. For many years, a routine practice has been to follow the patient monthly for 6–12 months, then every other month for a year, every 3 months for a year, every 4 months for a year, every 6 months for a year, and then annually. At each visit, a battery of laboratory and radiographic and imaging tests was obtained on the assumption that it is best to detect recurrent disease before it becomes symptomatic. However, where follow-up procedures have been examined, this assumption has been found to be untrue. Studies of breast cancer, melanoma, lung cancer, colon cancer, and lymphoma have all failed to support the notion that asymptomatic relapses are more readily cured by salvage therapy than symptomatic relapses. In view of the enormous cost of a full battery of diagnostic tests and their manifest lack of impact on survival, new guidelines are emerging for less frequent follow-up visits, during which the history and physical examination are the major investigations performed. As time passes, the likelihood of recurrence of the primary cancer diminishes. For many types of cancer, survival for 5 years without recurrence is tantamount to cure. However, important medical prob­ lems can occur in patients treated for cancer and must be examined (Chap. 100). Some problems emerge as a consequence of the disease and some as a consequence of the treatment. An understanding of these disease- and treatment-related problems may help in their detec­ tion and management. Despite these concerns, most patients who are cured of cancer return to normal lives. ■ ■SUPPORTIVE CARE In many ways, the success of cancer therapy depends on the success of the supportive care. Failure to control the symptoms of cancer and its treatment may lead patients to abandon curative therapy. Of equal importance, supportive care is a major determinant of quality of life. Even when life cannot be prolonged, the physician must strive to pre­ serve its quality. Quality-of-life measurements have become common endpoints of clinical research studies. Furthermore, palliative care has been shown to be cost-effective when approached in an organized fashion. A credo for oncology could be to cure sometimes, to extend life often, and to comfort always. Management strategies for cancer pain, nausea, and other common side effects of cancer and its treatment are outlined in Chap. 74. An approach to end-of-life care is provided in Chap. 13. Psychosocial Support  The psychosocial needs of patients vary with their situation. Patients undergoing treatment experience fear, anxiety, and depression. Self-image is often seriously compromised by deforming surgery and loss of hair. Women who receive cosmetic advice that enables them to look better also feel better. Loss of control over how one spends time can contribute to the sense of vulnerability. Juggling the demands of work and family with the demands of treat­ ment may create enormous stresses. Sexual dysfunction is highly prevalent and needs to be discussed openly with the patient. An empa­ thetic health care team is sensitive to the individual patient’s needs and permits negotiation where such flexibility will not adversely affect the course of treatment. Cancer survivors have other sets of difficulties. Patients may have fears associated with the termination of a treatment they associate with their continued survival. Adjustments are required to physical losses and handicaps, real and perceived. Patients may be preoccupied with minor physical problems. They perceive a decline in their job mobility and view themselves as less desirable workers. They may be victims of job and/or insurance discrimination. Patients may experience dif­ ficulty reentering their normal past life. They may feel guilty for hav­ ing survived and may carry a sense of vulnerability to colds and other illnesses. Perhaps the most pervasive and threatening concern is the ever-present fear of relapse (the Damocles syndrome). Patients in whom therapy has been unsuccessful have other prob­ lems related to the end of life. Death and Dying  The most common causes of death in patients with cancer are infection (leading to circulatory failure), respiratory failure, hepatic failure, and renal failure. Intestinal blockage may lead to inanition and starvation. Central nervous system disease may lead to seizures, coma, and central hypoventilation. About 70% of patients develop dyspnea preterminally. However, many months usually pass between the diagnosis of cancer and the occurrence of these compli­ cations, and during this period, the patient is severely affected by the possibility of death. The path of unsuccessful cancer treatment usually occurs in three phases. First, there is optimism at the hope of cure; when the tumor recurs, there is the acknowledgment of an incurable disease, and the goal of palliative therapy is embraced in the hope of being able to live with disease; finally, at the disclosure of imminent death, another adjustment in outlook takes place. The patient imagines the worst in preparation for the end of life and may go through stages of adjustment to the diagnosis. These stages include denial, isola­ tion, anger, bargaining, depression, acceptance, and hope. Of course, patients do not all progress through all the stages or proceed through them in the same order or at the same rate. Nevertheless, developing an understanding of how the patient has been affected by the diagnosis and is coping with it is an important goal of patient management. It is best to speak frankly with the patient and the family regarding the likely course of disease. These discussions can be difficult for the physician as well as for the patient and family. The critical features of the interaction are to reassure the patient and family that everything that can be done to provide comfort will be done. They will not be abandoned. Many patients prefer to be cared for in their homes or in a hospice setting rather than a hospital. The American College of Physi­ cians has published a book called Home Care Guide for Cancer: How to Care for Family and Friends at Home that teaches an approach to successful problem-solving in home care. With appropriate planning, it should be possible to provide the patient with the necessary medical care as well as the psychological and spiritual support that will prevent the isolation and depersonalization that can attend in-hospital death. CHAPTER 73 Approach to the Patient with Cancer The care of dying patients may take a toll on the physician. A “burn­ out” syndrome has been described that is characterized by fatigue, dis­ engagement from patients and colleagues, and a loss of self-fulfillment. Efforts at stress reduction, maintenance of a balanced life, and setting realistic goals may combat this disorder. End-of-Life Decisions  Unfortunately, a smooth transition in treatment goals from curative to palliative may not be possible in all cases because of the occurrence of serious treatment-related compli­ cations or rapid disease progression. Vigorous and invasive medical support for a reversible disease or treatment complication is assumed to be justified. However, if the reversibility of the condition is in doubt, the patient’s wishes determine the level of medical care. These wishes should be elicited before the terminal phase of illness and reviewed periodically. Information about advance directives can be obtained from the American Association of Retired Persons, 601 E Street, NW, Washington, DC 20049, 202-434-2277, or Choice in Dying, 250 West 57th Street, New York, NY 10107, 212-366-5540. Some states allow physicians to assist patients who choose to end their lives. This subject is challenging from an ethical and a medical point of view. Discussions of end-of-life decisions should be candid and involve clear informed consent, waiting periods, second opinions, and documentation. A full discussion of end-of-life management is provided in Chap. 13. ■ ■FURTHER READING Bray F et al: Global cancer statistics 2022: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries. CA Cancer J Clin 74:229, 2024. Hesketh PJ et al: Antiemetics: ASCO guideline update. J Clin Oncol 38:2782, 2020. Kelley AS, Morrison RS: Palliative care for the seriously ill. N Engl J Med 373:747, 2015. Martini RS et al: Integrative approaches for cancer pain management. Curr Oncol Rep 26:691, 2024. Samala RV et al: Frequently asked questions about managing cancer pain: An update. Cleve Clin Med J 88:183, 2021. Siegel RL et al: Cancer statistics, 2024. CA Cancer J Clin 74:12, 2024. # 03 - 74 Symptom Control in Patients with Cancer ### 74 Symptom Control in Patients with Cancer Charles L. Loprinzi, Thomas J. Smith Symptom Control in Patients with Cancer THE FIRST STEP: IMPORTANCE OF PROPER SYMPTOM ASSESSMENT AND RESOLUTION Several randomized trials have now shown that for metastatic cancer patients, prompt symptom assessment and resolution lead to substan­ tially increased survival. Basch and colleagues at Memorial Sloan Ket­ tering Cancer Center randomized 766 metastatic solid tumor patients to usual care or once-a-week monitoring of 12 common symptoms (the patient-reported outcomes [PRO] group); these patients checked in once a week by computer or smartphone. Nurses monitored the symptom for “spikes” such as in pain and contacted the patient or brought them in for evaluation. Quality of life was significantly better in the PRO group. Surprisingly, median overall survival (OS) was 31.2 months in the PRO group and 26 months in the usual care group (p = .03). There was an absolute difference in OS of 6 per 100 patients at 5 years in the PRO group compared to the control group. In a similar trial of 121 stage III and IV lung cancer patients randomized to usual care or once-weekly PRO reporting, the median OS was 22.5 months versus 13.5 months. The absolute OS difference at 2 years was 10–12 of every 100 patients. In a cluster randomized trial of 52 oncology practices and 1191 patients, PROs completed each week led to statistically significant improvements in quality of life outcomes at 3 months; the primary outcome, OS, has not been reported. This extra attention to symptom assessment and manage­ ment may be part of the reason that patients randomized to concurrent palliative care in addition to their cancer care live longer. PART 4 Oncology and Hematology A general principle from the above trials is that the health care pro­ vider should use some form of PRO-related scale to assess symptoms. Homsi et al. evaluated 200 patients referred to the Cleveland Clinic using a 48-item symptom checklist versus what the patients volun­ teered. The median number of volunteered symptoms was one; the median number using a checklist was 10. Fifty-two percent of these symptoms were rated moderate or severe, 48% mild, and 53% distress­ ing. Fatigue and pain were the most common symptoms reported in both groups. Not everyone has access to an electronic computer-based PRO system or the ability to integrate this into the electronic medical record (EMR). Readily available and free scales such as the Edmonton Symptom Assessment System–Revised can be done on paper or elec­ tronic tablets and pasted into the EMR. The most recent scale includes questions on spirituality and financial distress and is available in many languages (Fig. 74-1). Even with a nurse assisting the patient, the aver­ age completion time was only 117 s, so time should not be a barrier. Using pain as the most common example of cancer symptoms, many clinicians have been conditioned to use pain as the fifth vital sign and almost immediately ask for a number from 0–10. First, try to establish the generators of the symptom and classify it into a treatable subtype (Table 74-1). It may be helpful to categorize how much each symptom actually bothers the patient; for instance, anorexia may bother the family but not the patient. Next, clinicians can attempt to manage the cancer symptom. We have listed the most common cancer symptoms in Table 74-1 and will review each in turn, including some uncommon ones, and provide current therapeutic modalities. INDIVIDUAL SYMPTOMS ■ ■FATIGUE Frequency  Fatigue is the most commonly reported symptom by patients, with often an 80% or higher prevalence. Etiology  Fatigue can be due to the cancer, electrolyte abnormalities especially hypercalcemia, anemia, hypothyroidism, chemotherapy, and immunotherapy such as pembrolizumab, nivolumab, and ipilimumab. Besides general fatigue due to checkpoint inhibitors, 5–22% (average 6%) of patients will develop hypothyroidism and another 1–2% de novo hypophysitis. Assessment  Check for hypothyroidism, anemia, hypercalcemia and other electrolyte abnormalities, and renal failure, also screen for depression and/or demoralization. It is important to remember that while most cases of hypothyroidism manifest in 6–8 weeks, it can appear months after the patient has stopped the immunotherapy. Treatment  The simplest treatments consist of correcting anemia, hypothyroidism, and/or electrolyte abnormalities (hypercalcemia). There are few other modalities that work quickly or reliably. Paradoxi­ cally, structured exercise (e.g., 45 min of walking daily) has been shown to be preventative and therapeutic. Rather than prescribe a new exer­ cise regimen, ask the patient what they have done before and urge them to resume it. One can consider a trial of methylphenidate 5 mg at 7 and 11 a.m. for 48 h, with continuation if some benefit, or modafinil or congeners. Bupropion helps; in a systematic review, six of seven studies reported significant reductions in fatigue with minimal side effects. In a recent randomized trial, 40 patients were randomized to bupropion sustained release or placebo. The bupropion group had significant improvements in fatigue and quality of life but no improvements in depression. Steroids (e.g., dexamethasone 8 mg in the morning) can benefit some patients, usually toward the end of life. Long-term use has not been studied, and patients should be observed for hyperglycemia. ■ ■PAIN Frequency  At least 80% of cancer patients will experience pain during their lifetime. While secondary to fatigue in prevalence, it is the most feared symptom. Etiology  Try to characterize the type of pain (Table 74-2). Assessment  Ask for a 0–10 rating for best, worst, and average pain and what an acceptable pain score would be. List what the person has tried before, including acupuncture, massage, other alternative/ complementary treatments, and medications. Ascertain if the patient is on anticoagulants given the widespread use of novel oral anticoagu­ lants (NOACs). Treatment  •  NOCICEPTIVE PAIN  For nociceptive pain, start with acetaminophen, then nonsteroidal anti-inflammatory agents, and then opioids, which should always be used with constipationpreventing measures. Recent studies have shown that the addition of acetaminophen to high doses of opioids has no additional effect. Ste­ roids did slightly improve pain compared to placebo in cancer patients and improved fatigue, nausea, and well-being; a Cochrane systematic review found a reduction in pain of 0.84 on a 0-10 point scale at 1 week. VISCERAL PAIN  Visceral pain is among the hardest to treat of all pains. Nonsteroidal anti-inflammatory agents or neuropathic pain medica­ tions such as gabapentin or pregabalin, combined with opioids, may be required. Octreotide in combination with opioids reduces visceral hyperalgesia and may be helpful if nothing else works for malignant bowel obstruction. NEUROPATHIC PAIN  Several different classes of drugs are useful, but the number needed to treat ranges from 3 to 7 or even 10 for all of them. This necessitates 3- to 4-week trials of alternate drugs alone or in combination. Contrary to common teaching, randomized trials show that opioids do help neuropathic pain with as much benefit as gabapentin or nortriptyline; the combination is even more effective. A variety of neuropathic pain drugs are used: gabapentin, pregabalin, duloxetine, nortriptyline, amitriptyline, carbamazepine, lamotrigine, and many others. One systematic review reported that a reduction in cancer pain intensity of >1 point was unlikely with any of these drugs. Pain relief occurred in 4–8 days, if it occurred, so trials do not need to be >2–3 weeks. Chemotherapy-induced peripheral neuropathy (CIPN) is a promi­ nent clinical problem that is applicable to the vast majority of patients Edmonton Symptom Assessment Scale (ESAS–FS) Please circle the number that best describes your symptoms: No Pain No Fatigue Worst Fatigue No Nausea Worst Nausea No Depression Worst Depression No Anxiety Worst Anxiety No Drowsiness Worst Drowsiness No Shortness of Breath Worst Shortness of Breath Best Appetite Worst Appetite Best Feeling of Well-being Worst Feeling of Well-being Best Sleep Worst Sleep No Financial Distress (Distress/suffering experienced secondary to financial issues) No Spiritual Pain (Pain deep in your soul/being that is not physical) FIGURE 74-1  Edmonton Symptom Assessment System–Revised. TABLE 74-1  Common Cancer Symptoms and Their Association SYMPTOM PREVALENCE COMMONLY FOUND CAUSES/EXAMPLES Fatigue 70–80% Chemotherapy Immunotherapy Pain, all 40–70% overall   Nociceptive Pancreatic cancer pain   Visceral Intestinal obstruction   Neuropathic Chemotherapy-induced neuropathy   Incident (movement) Bone metastases Oral and gastrointestinal toxicity Dependent on agents used; estimates from 30 to 40% Standard chemotherapy such as doxorubicin Molecularly targeted agents such as palbociclib, infigratinib, everolimus, lenvatinib Radiation therapy Nausea due to chemotherapy Dependent on emetogenic potential of drugs administered; 10–90% Nausea not due to chemotherapy Limited information on incidence but common Due to small-bowel obstruction, opioids Anorexia/cachexia 20–80% due to cancer Most common in lung and pancreas cancers Dyspnea 10–80% during a lifetime, more common near end of life Most common in lung cancer patients or those with effusions, multiple pulmonary metastases Hot flashes Two-thirds of breast cancer and three-quarters of prostate cancer patients with androgen deprivation Nasal vestibulitis Up to 75% of patients Those receiving taxanes, bevacizumab, etc. Worst Pain CHAPTER 74 Symptom Control in Patients with Cancer Worst Financial Distress Worst Spiritual Pain Particularly common with cisplatin and doxorubicin Very common but often not reported by either men or women TABLE 74-2  Types of Commonly Encountered Cancer Pain TYPE OF PAIN CAUSE CHARACTERISTICS EXAMPLES Nociceptive Pressure on nerves Deep, dull, aching, constant and worsening with time Visceral Distention of a hollow viscus Cramping, bloating pain, intermittent Intestinal obstruction, renal colic Neuropathic Direct damage to the nerves from cancer, treatment, or both Local pain, sharp shooting, burning, stabbing, often with allodynia (painful sensation with normal touch) or hyperalgesia Chemotherapy-induced neuropathic pain; direct damage to the longest nerves with damaged receptors and even loss of nerve fiber density Numbness, tingling, pain, which may be mixed together; longest nerves affected most, giving a stocking-glove neuropathy Incident or movement pain Pathologic fractures, bone damage from cancer, residual damage left after cancer Minimal pain at rest, but excruciating pain with movement “bone on bone” receiving chemotherapy. Some chemotherapeutic agents are much more prone to cause neuropathy than are others. Among the biggest offenders are taxanes, platinums, epothilones, eribulin, vinca alka­ loids, bortezomib, and lenalidomide. At the time that this chapter was written, there were no clearly established means for preventing CIPN from any agent, other than decreasing the dose or stopping the offend­ ing drug. The most promising approach at the time this chapter was penned involved attempts to decrease the concentration of paclitaxel in the peripheral extremities using cryotherapy, compression therapy, or both. Multiple preliminary trials have suggested that these approaches are helpful. In 2024, a randomized clinical trial is ongoing to com­ pare compression therapy versus cryo-compression therapy versus a control arm (minimal compression that is not thought to be enough to decrease paclitaxel delivery to the distal extremities). At present, American Society of Clinical Oncology (ASCO) guidelines suggest that in patients who develop substantial CIPN in the midst of a treatment course, the attending clinicians should consider stopping the offending chemotherapy drug(s) or attenuating their dose. PART 4 Oncology and Hematology In terms of treating established CIPN in patients who have com­ pleted all planned neurotoxic chemotherapy, there is evidence from more than one clinical trial that supports that duloxetine can attenuate established neuropathy symptoms to a small degree (0.6–1.0 on a 0–10 scale). Currently, there are no other proven treatments for treating established CIPN. INCIDENT (MOVEMENT) PAIN DUE TO BONE METASTASES  There is minimal evidence for any one modality to treat this type of pain. In one convenience trial, six of six patients with bone metastasis– incident pain had complete or near-complete responses to low doses of gabapentin (100–200 mg three times a day) added to opioids, but this has not been repeated (trial in the works). There is one case report of complete pain remission for weeks until death after four treatments with Scrambler Therapy, a form of cutaneous nerve stimulation, and one report of “burst” ketamine with morphine. ■ ■GASTROINTESTINAL AND ORAL MUCOSITIS RELATED TO TREATMENT Frequency  Oral mucositis varies by drug but is reported in 30–40% of people receiving molecularly targeted agents such as regorafenib, sorafenib, or erdafitinib, or the breast cancer drug palbociclib. The worst offending chemotherapy drug for oral mucositis, fluorouracil, is not used frequently anymore. The most common cause of oral mucosi­ tis among commonly used chemotherapy drugs is doxorubicin. Gastrointestinal (GI) mucositis can involve the entire GI tract, and estimates range from 50–80% of cancer patients experiencing some level of chemotherapy-induced diarrhea. Etiology  The most common cause is interference by the tyrosine kinase inhibitors with endothelial growth factor receptors (GFRs) or vascular GFRs. Drugs used for both chemotherapy and immune sup­ pression, such as everolimus, cause both inflammation and the usual disruption of endothelial cells. At its worst, the entire GI tract can be Pancreatic cancer pain, deep boring, and epigastric Increasingly common and dose limiting; 40–70% of people getting modern treatments. Duloxetine only proven medication, which is only moderately effective. Very difficult to control denuded, and the intestine cannot reabsorb the 25 L of intestinal fluid made daily, producing high-output diarrhea. Most mucositis happens 7–10 days after treatment. Assessment  If the time course is right and the patient has received a drug known to cause mucositis, suspicion should be high. Other considerations for oral mucositis include thrush, aphthous stomatitis, herpes, or other infections. Exam may show denuded raw areas that are very painful. GI mucositis is usually manifest by diarrhea, often accompanied by cramps and pain. The diarrhea can be copious, resulting in liters per day. If the time course is not right (very soon or weeks after cancer therapy initiation), other causes such as infections or too many laxa­ tives should be sought. Treatment  For patients receiving bolus fluorouracil, sucking on ice chips during infusion (oral cryotherapy) reduces the incidence and severity by ~50%. There is conflicting evidence on the use of oral dexa­ methasone or other steroid rinses to prevent oral mucositis from drugs such as everolimus and palbociclib. Most studies show improvement after treatment with glucocorticoid rinses, regardless of the steroid. Viscous lidocaine 2% is commonly recommended for pain. For ulcer­ ations, topical high-potency steroids are indicated, and a short course of high-dose steroids may be necessary. For GI mucositis manifested as diarrhea, loperamide is the first choice, up to 24 mg a day. Octreotide up to 300 mg a day is reserved for refractory cases. Glucocorticoids are also commonly employed. ■ ■NAUSEA AND VOMITING RELATED TO CHEMOTHERAPY Frequency and Etiology  It is well established that chemotherapy can cause substantial nausea and/or vomiting, noting that this problem is strongly associated with individual chemotherapy agents. Some agents, such as cisplatin and doxorubicin, cause substantial nausea and vomiting, whereas other agents, such as fluorouracil, do not cause any substantial nausea and vomiting. Assessment  Clinical determination of whether a patient developed nausea or vomiting from chemotherapy is obtained by talking to the patient and/or their family and asking questions regarding these symp­ toms. This is often done when the patient comes back for another cycle of therapy. Clinical trials use established PRO data that could also be used in clinical practice. In clinical trials, data are usually obtained before chemotherapy and then daily for a few days after each chemo­ therapy dose. Treatment  With highly emetogenic chemotherapy regimens, anti­ emetic drugs are started with initiation of chemotherapy and com­ monly given for a few days thereafter. Dexamethasone was established as a helpful agent in the 1970s. In the 1990s, 5-HT3 receptor antagonists became established agents. In the 2000s, NK1 receptor antagonists were established as helpful agents for decreasing nausea and vomiting in the days following highly emetogenic chemotherapy. These agents did not decrease nausea and vomiting in the first 24 h, as did the 5-HT3 receptor antagonists; thus, NK1 receptor antagonists were added to the antiemetic cocktail as opposed to replacing 5-HT3 receptor antagonists. In the 2010s, olanzapine was demonstrated to decrease nausea and vomiting when added to the three drug classes discussed above. Olan­ zapine appears to be the most effective of all of the drugs mentioned in this section, potentially paving the way for decreasing use of other agents in the four-drug antiemetic cocktail described above. Decreas­ ing dexamethasone doses and/or durations might decrease long-term dexamethasone-associated toxicity. ■ ■NAUSEA AND VOMITING UNRELATED TO CHEMOTHERAPY Frequency  No recent data are available, but it is estimated that this problem affects up to 40–70% of patients. Etiology  Nausea and vomiting in patients with cancer, not associ­ ated with chemotherapy, can be associated with multiple other etiolo­ gies, such as radiation therapy, bowel obstruction, other medications, electrolyte abnormalities, post-anesthesia, and cerebral metastases. Assessment  Clinical determination of whether a patient has nausea or vomiting is obtained from talking to the patient and/or their family and asking questions regarding these symptoms. In clinical trials, data are generally obtained daily, including the day prior to the planned intervention and then for a few days following a proposed intervention. Treatment  A variety of drugs have been studied for treating nausea and vomiting in this situation, but none of them are very effective; these include diphenhydramine, metoclopramide, prochlorperazine, haloperi­ dol, methotrimeprazine, dexamethasone, ondansetron, and dronabinol. In 2020, a double-blind, placebo-controlled clinical trial demon­ strated that a relatively low dose of olanzapine (5 mg/d) was very effective for decreasing nausea and vomiting in patients with advanced cancer who had not received chemotherapy or radiation therapy for at least 2 weeks prior to study entry. In this trial involving a total of 30 patients, nausea scores decreased from 9/10 to 2/10 on the day after olanzapine was started, in comparison to the placebo group whose nausea scores were 9/10 on both the day before and the day after the first dose of the placebo (p <.001). Another trial, published in 2023, demonstrated that 2.5 mg/d of olanzapine markedly reduced nausea and vomiting in patients with advanced cancer who were not receiving highly emetogenic chemotherapy. ■ ■ANOREXIA AND CACHEXIA Frequency  Up to 20% of all cancer deaths are strongly associated with cancer cachexia. Anorexia is even more common, affecting 5–25% of community-dwelling adults and twice that number of patients with cancer. Etiology  Although most anorexia is caused by release of hormones by cancer, it can be aggravated by drug treatments, radiation, mechanical dif­ ficulties in eating, and food insecurity. Cachexia is multifactorial and char­ acterized by weight loss of skeletal muscle and adipose tissue, an imbalance in metabolic regulation, and reduced food intake. In general, cancer cachexia cannot be reversed by simply replacing calories and nutrients. Assessment  Anorexia is determined simply by asking the patient and family about appetite. Cachexia has been variously defined as 5 or 10% loss of precancer weight. More precise definitions have included the presence of fatigue, anorexia, increased inflammatory markers such as C-reactive protein, body mass index <20, and even sarcopenia on a computed tomography scan. Treatment  Treatment is often unsatisfactory for both patients and their families. A systematic review done for an ASCO guideline regarding this topic showed that dietary counseling was associated with increased weight gain in some but not all trials and can be rea­ sonably offered. The magnitude of this approach, however, is not large. Enteral feeding tubes and intravenous nutrition are not recommended and should not be used routinely. For anorexia, olanzapine is recom­ mended as the first-line agent and the only agent with good evidence of benefit without potentially serious harm. In the largest randomized controlled trial, 124 solid tumor patients received olanzapine 2.5 mg at bedtime versus placebo. Sixty percent of the olanzapine patients increased their weight by at least 5% versus 9% of placebo patients (p <.001). Mirtazapine, which is commonly prescribed, was ineffective in a large randomized trial and should not be used. Megestrol acetate and corticosteroids do increase appetite in afflicted patients and lead to some weight gain but have untoward side effects and do not appear to improve patient survival. A novel approach is to block the elevated lev­ els of growth differentiation factor 15 (GDF-15), a serum cytokine that is elevated in cachexia with ponsegromab. This monoclonal antibody was associated with improved appetite, weight, and physical activity in a randomized phase 2 trial, but it has not been approved by the FDA. ■ ■CONSTIPATION Frequency  Constipation occurs in 20–90% of all cancer patients at some time in their trajectory and can be both painful and associated with anorexia and nausea. CHAPTER 74 Etiology  Causes include commonly used drugs such as opioids, acetaminophen, ondansetron, chemotherapy (vandetanib, thalido­ mide, lenalidomide), and noncancer drugs such as diuretics and antidementia drugs. Inactivity, dehydration, a low-fiber diet, hypercal­ cemia, and hypothyroidism (including up to 20% of patients receiving checkpoint inhibitors) can all be contributing factors. Symptom Control in Patients with Cancer Assessment  Clinicians should ask what the personal bowel habits have been and when the patient last had a bowel movement. If it was 3 or more days ago, constipation is highly likely. Using a specific scale or grading the consistency of the stool is not recommended. Treatment  Good bowel hygiene starts with prevention and using drugs that the patient can tolerate. Every opioid prescription should be accompanied by a plan to prevent constipation. Senna is the first choice, starting at 1–2 tablets a day and working up to 8, along with sufficient hydration. Some patients may have cramps from the stimulant action requiring multiple doses a day or switching drugs. Polyethylene glycol is added next, if needed and/or if senna is not tolerated. Lactulose and sor­ bitol are less commonly used because they commonly are less palatable. Magnesium oxide (1 oz of a 300-mL bottle hourly until movements start) can be helpful. Patients on opioids who are refractory to these measures usually have success with opioid antagonists that reverse the opioid in the periphery but not the brain. Because of cost, these agents currently may require insurance preauthorization, so they are likely not used very often. ■ ■DYSPNEA Frequency  Dyspnea (or breathlessness or air hunger) is, like pain, a subjective experience that can only be assessed by the patient. Dyspnea is common, with 10–70% of patients reporting it, especially toward the end of life. Dyspnea portends a poor prognosis in advanced cancer with an average survival of only days, weeks, or months, and should trigger serious illness conversations such as being fully truthful about prognosis and creation of an advance directive. ASCO guidelines rec­ ommend a systematic assessment for dyspnea at every inpatient and outpatient visit in patients with advanced cancer. Etiology  As with most cancer symptoms, dyspnea is multifactorial. Lung dysfunction may be due to the cancer, radiation, chemotherapy, and/or immunotherapy. With immunotherapy, the average time to onset was 52 days in one trial, and the incidence in one large series was 9.5%. Assessment  The first attempt should be to find something that is reversible (e.g., hypoxia, pneumonia, pulmonary embolism, pleural effusion, chronic obstructive pulmonary disease, asthma, or bronchial constriction due to cancer). Next should come a careful review of medication history, especially for checkpoint inhibitors, remembering that pneumonitis may develop months after the immunotherapy has stopped. The impact of the dyspnea on the patient and the family should be assessed. Management of immunotherapy-related lung dis­ ease may best be done by experts, as the therapies can be challenging and have been rapidly changing. Treatment  Treatment of the cancer, if deemed to have a good chance of success, should be a mainstay. Other contributing factors such as anxiety or chronic obstructive pulmonary disease (COPD) should be maximally treated. High-dose steroids are commonly used in the setting of lymphangitic carcinomatosis, COPD, or asthma. Opi­ oids at low doses are generally safe and can be helpful in relieving air hunger, and low-dose benzodiazepines can help relieve anxiety. A fan blowing cold air across the face can give some comfort. Supplemental oxygen should be available for patients with hypox­ emia (i.e., SpO2 ≤90% on room air). High-flow nasal oxygen (HFNO) is often used as a bridge to a next therapy, if there is one; commitment to HFNO complicates referral to hospice or home due to the cost. Refer­ ral to palliative care should always be considered, along with truthful information about prognosis and a serious illness conversation includ­ ing advance directives. ■ ■HOT FLASHES PART 4 Oncology and Hematology Frequency  Hot flashes are common; they occur in about twothirds of postmenopausal women treated for breast cancer, and almost half have night sweats. Of men treated with chemical or surgical orchiectomy for prostate cancer, three-quarters will have hot flashes. Common knowledge, in the not too distant past, was that hot flashes usually only lasted a couple of years. However, it is now understood that patients can have them for decades. Etiology  Lack of estrogen or testosterone is the proximate cause of hot flashes, especially when the decrease is rapid. Assessment  Asking about hot flashes, including frequency, sever­ ity, and interference with life, should be part of the appropriate care of prostate or breast cancer patients. Treatment  •  FEMALES  In the 1990s, four separate individuals clinically noted that patients receiving newer antidepressants, at least new at that time, appeared to have reduced hot flashes; these antide­ pressants were venlafaxine, paroxetine, sertraline, and fluoxetine. Such observations resulted in randomized, placebo-controlled clinical trials that showed that these and other antidepressants substantially helped women with hot flashes. The authors of this chapter, when it is decided to utilize an antidepressant for treating hot flashes, recommend citalo­ pram, 20 mg/d, as it appears as effective as other antidepressants and is well tolerated. Gabapentin also has efficacy against hot flashes and reduces anxiety in breast cancer survivors. Oxybutynin, immediate or sustained release, also showed efficacy in randomized trials. This can be a relatively inexpensive treatment approach. Caution is recom­ mended in older women, as there are concerns regarding mental status changes in the setting of long-term use. In refractory patients, 20–40 mg of megestrol acetate a day can control hot flashes. For women who desire a one-time intramuscular injection, 400–500 mg of medroxyprogester­ one acetate can nicely decrease hot flashes for many months. Fezolinetant, an NK3 receptor antagonist, became clinically avail­ able in 2023 as a nonhormonal agent for treating hot flashes in women in general. Although it works as well as some of the other treatments noted above, cross-study comparisons of the efficacy of this drug to the other options mentioned above suggest that hot flash reductions are similar. In a series of studies that included >1300 patients, some with a history of breast cancer (which amounted to ~75% of the subjects) and some without a history of breast cancer (the other 25% of patients), hot flash outcomes were similar. Additionally, this article revealed that hot flash reductions were similar whether or not a patient was receiving tamoxifen. MALES  Pilot trials of venlafaxine and paroxetine supported that they were useful for alleviating hot flashes in men with prostate cancer. However, a randomized trial was not able to demonstrate significant benefit from venlafaxine for controlling hot flashes in men. A prospec­ tive, randomized, placebo-controlled trial demonstrated that 900 mg/d of gabapentin works well for treating hot flashes in men, similarly to how it works in women. Progesterone analogues also decrease hot flashes in men, similarly to how they do so in women. Case reports support that oxybutynin is helpful in men with hot flashes; a recently completed randomized, double-blind, placebocontrolled clinical trial demonstrated that this drug nicely decreased hot flashes in this population, too. ■ ■NASAL VESTIBULITIS Frequency  Nasal vestibulitis refers to an unpleasant inflamma­ tion of the vestibule of the nose. An observational interview study of patients who had received at least 6 weeks of chemotherapy noted that >70% of those receiving taxanes and >80% of those receiving bevaci­ zumab experienced untoward nasal symptoms, such as pain, bleeding, and/or scabbing. A prospective study of patients receiving a variety of different chemotherapy regimens illustrated that >75% of patients who received paclitaxel, nab-paclitaxel, or bevacizumab developed bother­ some nasal symptoms in the following weeks to months. Etiology  Chemotherapy can damage the epithelial cells in the nose, leading to dryness, cracking, and secondary infection. Like mucositis, it generally heals in 7–10 days but is a potential source for infection. Assessment  Asking about symptoms of dryness, bleeding, crust­ ing, or pain and an exam should confirm local tissue irritation. Treatment  Nasal sprays of saline and of rose geranium in sesame oil have been used to treat this clinical problem, with data supporting that the latter is more beneficial. This will have to be compounded; the recipe is available from the authors or the Mayo Clinic. ■ ■FURTHER READING Basch E et al: Overall survival results of a trial assessing patientreported outcomes for symptom monitoring during routine cancer treatment. JAMA 318:197, 2017. Correa-Morales JE et al: Cancer and non-cancer fatigue treated with bupropion: A systematic review. J Pain Symptom Manage 65:e21, 2023. Finnerup NB et al: Neuropathic pain: From mechanisms to treatment. Physiol Rev 101:259, 2021. Groarke JD et al: Ponsegromab for the Treatment of Cancer Cachexia. N Engl J Med 391:2291, 2024. Homsi J et al: Symptom evaluation in palliative medicine: Patient report vs systematic assessment. Support Care Cancer 14:444, 2006. Hui D, Bruera E: The Edmonton Symptom Assessment System 25 years later: Past, present, and future developments. J Pain Symptom Man­ age 53:630, 2017. Loprinzi CL et al: Prevention and management of chemotherapyinduced peripheral neuropathy in survivors of adult cancers: ASCO guideline update. J Clin Oncol 38:3325, 2020. Mannix KA: Palliation of nausea and vomiting, in Oxford Textbook of Palliative Medicine, 2nd ed. Doyle D et al (eds). Oxford, UK, Oxford University Press, 1998, p. 48. Molinares D et al: Chemotherapy-induced peripheral neuropathy: Diagnosis, agents, general clinical presentation, and treatments. Curr Oncol Rep 25:1227, 2023. Navari RM et al: Olanzapine for the treatment of advanced cancerrelated chronic nausea and/or vomiting: A randomized pilot trial. JAMA Oncol 6:895, 2020. Roeland EJ et al: Cancer Cachexia Expert Panel. Cancer cachexia: ASCO guideline rapid recommendation update. J Clin Oncol 41:4178, 2023. Smith TJ, Saiki CB: Cancer pain management. Mayo Clin Proc 90:1428, 2015. # 04 - 75 Prevention and Early Detection of Cancer ### 75 Prevention and Early Detection of Cancer Jennifer M. Croswell, Otis W. Brawley, Barnett S. Kramer Prevention and Early Detection of Cancer Improved understanding of carcinogenesis has allowed cancer preven­ tion and early detection to expand beyond identification and avoid­ ance of carcinogens. Specific interventions to reduce cancer mortality by preventing cancer in those at risk and effective screening for early detection of cancer are the goals. Carcinogenesis is a process that usually extends over years, a con­ tinuum of discrete tissue and cellular changes over time resulting in aberrant physiologic processes. Prevention concerns the identification and manipulation of the biologic, environmental, social, and genetic factors in the causal pathway of cancer. Examination of national epide­ miologic patterns can provide indicators of the relative contributions of advances in prevention, screening, and therapy in progress against cancer, but randomized trials provide the best evidence to guide prac­ tice, especially in the healthy general population. EDUCATION AND HEALTHFUL HABITS Public education on the avoidance of identified risk factors for cancer and encouraging healthy habits contributes to cancer prevention. The clinician is a powerful messenger in this process. The patient-provider encounter provides an opportunity to teach patients about the hazards of smoking, influence of a healthy lifestyle and other exposures, and use of proven cancer screening methods. ■ ■SMOKING CESSATION Tobacco smoking is a strong, modifiable risk factor for cardiovascu­ lar disease, pulmonary disease, and cancer. Smokers have an ∼1 in 3 lifetime risk of dying prematurely from a tobacco-related cancer, car­ diovascular, or pulmonary disease, and cigarette smoking shortens life expectancy, on average, by a decade. Tobacco use causes more deaths from cardiovascular disease than from cancer. Lung cancer and cancers of the larynx, oropharynx, esophagus, kidney, bladder, colon, pancreas, stomach, and uterine cervix are all tobacco related. The number of cigarettes smoked per day and the level of inhalation of cigarette smoke are correlated with risk of lung cancer mortality. Light- and low-tar cigarettes are not safer because smokers tend to inhale them more frequently and deeply. Those who stop smoking have a 30–50% lower 10-year lung cancer mortality rate compared to those who continue smoking, despite the fact that some carcinogen-induced gene mutations persist for years after smoking cessation. Smoking cessation and avoidance would save more lives from cancer than any other public health activity. The risk of tobacco smoke is not limited to the smoker. Environ­ mental tobacco smoke, known as secondhand or passive smoke, is carcinogenic and associated with a variety of respiratory illnesses in exposed children. Tobacco use prevention is a pediatric issue. More than 80% of adult American smokers began smoking before the age of 18 years. Tradi­ tional cigarette smoking has declined substantially in recent years: for example, for high school seniors between 2012 and 2019, prevalence of past 30-day cigarette smoking dropped from 19% to 7% for boys and 7% to 2% for girls. Electronic cigarettes, on the other hand, are rapidly increasing in use: in 2020, approximately 20% of high school students reported being current electronic cigarette users. Counseling of ado­ lescents and young adults is critical to prevent all forms of tobacco use. A clinician’s simple advice can be of benefit. Providers should query patients on tobacco use and offer smokers assistance in quitting or referrals to cessation programs. Current approaches to smoking cessation recognize nicotine in tobacco as addicting (Chap. 465). The smoker who is quitting goes through identifiable stages, including contemplation of quitting, an action phase in which the smoker quits, and a maintenance phase. Smokers who quit completely are more likely to be successful than those who gradually reduce the number of cigarettes smoked or change to lower-tar or lower-nicotine cigarettes. Organized cessation programs may help individual efforts. Heavy smokers may need an intensive broad-based cessation program that includes counseling, behavioral strategies, and pharmacologic adjuncts, such as nicotine replacement (gum, patches, sprays, lozenges, and inhalers), bupropion, and/or varenicline. Electronic cigarettes have been advocated as a tool to achieve smoking cessation or as a harm reduction strategy in adults, but the net effects of electronic cigarettes on health are poorly studied. Absence of strict manufacturing controls of vaping material has pro­ duced serious injury. The health risks of cigars are similar to those of cigarettes. Smok­ ing one or two cigars daily doubles the risk for oral and esophageal cancers; smoking three or four cigars daily increases the risk of oral cancers more than eightfold and esophageal cancer fourfold. The risks of occasional use are unknown. Smokeless tobacco also represents a substantial health risk. Chewing tobacco is linked to dental caries, gingivitis, oral leukoplakia, and oral cancer. The systemic effects of smokeless tobacco (including snuff) may increase risks for other cancers. Esophageal cancer is linked to carcinogens in tobacco dissolved in saliva and swallowed. CHAPTER 75 ■ ■PHYSICAL ACTIVITY Physical activity is associated with a decreased risk of colon and breast cancer. A variety of mechanisms have been proposed. However, such studies are prone to confounding factors such as recall bias, association of exercise with other health-related practices, and effects of preclinical cancers on exercise habits (reverse causality). Prevention and Early Detection of Cancer ■ ■DIET MODIFICATION International ecologic studies suggest that diets high in fat are associ­ ated with increased risk for cancers of the breast, colon, prostate, and endometrium. Despite correlations, dietary fat has not been proven to cause cancer. Case-control and cohort epidemiologic studies give conflicting results. Diet is a highly complex exposure to many nutrients and chemicals. Low-fat diets are associated with many dietary changes beyond simple subtraction of fat. Other lifestyle factors are also associ­ ated with adherence to a low-fat diet. In some observational studies, dietary fiber has been associated with a reduced risk of colonic polyps and invasive cancer of the colon. Two large prospective cohort studies of >100,000 health professionals showed no association between fruit and vegetable intake and risk of cancer, however. Cancer-protective effects of increasing fiber and lowering dietary fat have not been shown in the context of a prospec­ tive clinical trial. The Polyp Prevention Trial randomly assigned 2000 elderly persons, who had polyps removed, to a low-fat, high-fiber diet versus routine diet for 4 years. No differences were noted in polyp formation. The U.S. National Institutes of Health Women’s Health Initiative, launched in 1994, was a long-term clinical trial enrolling >100,000 women age 45–69 years. It placed women into 22 intervention groups. Participants received calcium/vitamin D supplementation; hormone replacement therapy; and counseling to increase exercise, eat a lowfat diet with increased consumption of fruits, vegetables, and fiber, and cease smoking. The study showed that although dietary fat intake was lower in the diet intervention group, invasive breast cancers were not reduced over an 8-year follow-up period compared to the control group. Additionally, no reduction was seen in the incidence of colorec­ tal cancer in the dietary intervention arm. In the aggregate, cohort studies and randomized trials suggest that reduction of red meat or processed meat consumption has a small (if any) effect on cancer incidence and mortality, although the overall evidence base is weak. Evidence does not currently establish the anticarcinogenic value of vitamin, mineral, or nutritional supplements in amounts greater than those provided by a balanced diet. ■ ■ENERGY BALANCE Risk of certain cancers appears to increase modestly (relative risks gen­ erally in the 1.0–2.0 range) as body mass index (BMI) increases beyond 25 kg/m2. A cohort study of >5 million adults included in the U.K. Clinical Practice Research Datalink (a primary care database) found that each 5 kg/m2 increase in BMI was linearly associated with cancers of the uterus, gallbladder, kidney, cervix, thyroid, and leukemia. High BMI appears to have an inverse association with prostate and premeno­ pausal breast cancer. ■ ■SUN AVOIDANCE Nonmelanoma skin cancers (basal cell and squamous cell) are induced by cumulative exposure to ultraviolet (UV) radiation. Evidence for a direct association between cumulative UV exposure and melanoma is weaker. Reduction of sun exposure through use of protective clothing and changing patterns of outdoor activities can reduce skin cancer risk. Sunscreens decrease the risk of actinic keratoses, the precursor to squamous cell skin cancer, but melanoma risk may not be reduced. Sunscreens prevent burning, but they may encourage more prolonged exposure to the sun and may not filter out wavelengths of energy that cause melanoma. Appearance-focused behavioral interventions in young women can decrease indoor tanning use and other UV exposures and may be more effective than messages about long-term cancer risks. Those who recognize themselves as being at risk tend to be more compliant with sun-avoidance recommendations. Risk factors for melanoma include a propensity to sunburn, a large number of benign melanocytic nevi, and atypical nevi. However, about 70–80% of melanomas arise de novo, rather than from existing benign nevi. PART 4 Oncology and Hematology CANCER CHEMOPREVENTION Chemoprevention involves the use of specific natural or synthetic chemical agents to reverse, suppress, or prevent carcinogenesis before the development of invasive malignancy. Cancer develops through an accumulation of tissue abnormalities associated with genetic and epigenetic changes, and growth regulatory pathways that are potential points of intervention to prevent cancer. The initial changes are termed initiation. The alteration can be inher­ ited or acquired through the action of physical, infectious, or chemical carcinogens. Like most human diseases, cancer arises from an interaction between genetics and environmental exposures (Table 75-1). Influences that cause the initiated cell and its surrounding tissue microenviron­ ment to progress through the carcinogenic process and change phe­ notypically are termed promoters. Promoters include hormones such as androgens, linked to prostate cancer, and estrogen, linked to breast and endometrial cancer. The difference between an initiator and pro­ moter is indistinct; some components of cigarette smoke are “complete carcinogens,” acting as both initiators and promoters. Cancer can be prevented or controlled through avoidance of the factors that cause cancer initiation, promotion, or progression. Compounds of interest in chemoprevention may have antimutagenic, hormone modulation, anti-inflammatory, antiproliferative, or proapoptotic activity (or a combination). ■ ■CHEMOPREVENTION OF CANCERS OF THE UPPER AERODIGESTIVE TRACT Smoking causes diffuse epithelial injury in the oral cavity, esophagus, and lung. Patients cured of squamous cell cancers of the lung, esopha­ gus, and oral cavity are at risk (as high as 5% per year) of developing second cancers of the upper aerodigestive tract. Cessation of cigarette smoking does not markedly decrease the cured cancer patient’s risk of second malignancy, even though it does lower the cancer risk in those who have never developed a malignancy. Persistent oral human papillomavirus (HPV) infection, particularly HPV-16, increases the risk for cancers of the oropharynx. This associa­ tion exists even in the absence of other risk factors such as smoking or alcohol use (although the magnitude of increased risk appears greater than additive when HPV infection and smoking are both present). Oral HPV infection is believed to be largely sexually acquired. The use of TABLE 75-1  Suspected Carcinogens CARCINOGENSa ASSOCIATED CANCER OR NEOPLASM Alkylating agents Acute myeloid leukemia, bladder cancer Androgens Prostate cancer Aromatic amines (dyes) Bladder cancer Arsenic Cancer of the lung, skin Asbestos Cancer of the lung, pleura, peritoneum Benzene Acute myelocytic leukemia Chromium Lung cancer Diethylstilbestrol (prenatal) Vaginal cancer (clear cell) Epstein-Barr virus Burkitt’s lymphoma, nasal T-cell lymphoma Estrogens Cancer of the endometrium, liver, breast Ethyl alcohol Cancer of the breast, liver, esophagus, head and neck Helicobacter pylori Gastric cancer, gastric mucosa-associate lymphoid tissue (MALT) lymphoma Hepatitis B or C virus Liver cancer Human immunodeficiency virus Non-Hodgkin’s lymphoma, Kaposi’s sarcoma, squamous cell carcinomas (especially of the urogenital tract) Human papillomavirus Cancers of the cervix, anus, oropharynx Human T-cell lymphotropic virus type 1 (HTLV-1) Adult T-cell leukemia/lymphoma Immunosuppressive agents (azathioprine, cyclosporine, glucocorticoids) Non-Hodgkin’s lymphoma Ionizing radiation (therapeutic or diagnostic) Breast, bladder, thyroid, soft tissue, bone, hematopoietic, and many more Nitrogen mustard gas Cancer of the lung, head and neck, nasal sinuses Nickel dust Cancer of the lung, nasal sinuses Diesel exhaust Lung cancer (miners) Phenacetin Cancer of the renal pelvis and bladder Polycyclic hydrocarbons Cancer of the lung, skin (especially squamous cell carcinoma of scrotal skin) Radon gas Lung cancer Schistosomiasis Bladder cancer (squamous cell) Sunlight (ultraviolet) Skin cancer (squamous cell and likely melanoma) Tobacco (including smokeless) Cancer of the upper aerodigestive tract, bladder, kidney Vinyl chloride Liver cancer (angiosarcoma) aAgents that are thought to act as cancer initiators and/or promoters. the HPV vaccine is associated with a reduction in prevalence of oro­ pharyngeal infection rates and may eventually reduce oropharyngeal cancer rates. Oral leukoplakia, a premalignant lesion commonly found in smok­ ers, has been used as an intermediate marker of chemopreventive activity in smaller shorter-duration, randomized, placebo-controlled trials. Although therapy with high, relatively toxic doses of isotretinoin (13-cis-retinoic acid) causes regression of oral leukoplakia, more toler­ able doses of isotretinoin have not shown benefit in the prevention of head and neck cancer. Several large-scale trials have assessed agents in the chemopreven­ tion of lung cancer in patients at high risk. In the α-tocopherol/βcarotene (ATBC) Lung Cancer Prevention Trial, participants were male smokers with an average 30-plus pack-year history, age 50–69 years at entry. After median follow-up of 6 years, lung cancer incidence and mortality were statistically significantly increased in those receiving β-carotene. α-Tocopherol had no effect on lung cancer mortality, but patients receiving it had a higher incidence of hemorrhagic stroke. The β-Carotene and Retinol Efficacy Trial (CARET) involved 17,000 American smokers and workers with asbestos exposure. This trial also demonstrated harm from β-carotene: a lung cancer rate of 5 per 1000 subjects per year for those taking placebo versus 6 per 1000 subjects per year for those taking β-carotene. The ATBC and CARET results demonstrate the importance of testing chemoprevention hypotheses in randomized trials before widespread implementation because the results contradict a number of observational studies. ■ ■CHEMOPREVENTION OF COLON CANCER No agent with sufficient evidence exists at present for the prevention of colon cancer in the general population. A meta-analysis of four randomized controlled trials primarily designed to examine aspirin’s effects on cardiovascular events found no association between low-dose aspirin use and colorectal cancer inci­ dence at up to 10 years of follow-up. The same review reported highly variable results for colorectal cancer mortality and aspirin use and noted that, overall, studies have not been adequately powered to assess aspirin’s effects on colorectal cancer deaths. As such, the evidence is insufficient that nonsteroidal anti-inflammatory drugs (NSAIDs) reduce colorectal cancer incidence or mortality. However, there is clear evidence that regular NSAID use is associated with important bleeding harms, such as major gastrointestinal and intra- and extracranial bleed­ ing, particularly with increasing dosage and age. Cyclooxygenase-2 (COX-2) inhibitors have been considered for colorectal cancer and polyp prevention. Trials with COX-2 inhibitors were initiated, but an increased risk of cardiovascular events in those taking the COX-2 inhibitors was noted, so these agents are not suitable for chemoprevention in the general population. The Women’s Health Initiative demonstrated that postmenopausal women taking estrogen plus progestin have a 44% lower relative risk of colorectal cancer compared to women taking placebo. Of >16,600 women randomized and followed for a median of 5.6 years, 43 inva­ sive colorectal cancers occurred in the hormone group and 72 in the placebo group. The positive effect on colon cancer is mitigated by the modest increase in cardiovascular and breast cancer risks associated with combined estrogen plus progestin therapy, and guidelines do not recommend hormonal therapy as a standard preventive agent for colorectal cancer incidence or mortality. Most case-control and cohort studies have not confirmed early reports of an association between regular statin use and a reduced risk of colorectal cancer. No randomized controlled trials have addressed this hypothesis. A meta-analysis of statin use showed no protective effect of statins on overall cancer incidence or death. ■ ■CHEMOPREVENTION OF BREAST CANCER Tamoxifen is an antiestrogen with partial estrogen agonistic activity in some tissues, such as endometrium and bone. One of its actions is to upregulate transforming growth factor β, which decreases breast cell proliferation. In a randomized placebo-controlled prevention trial involving >13,000 pre- and postmenopausal women at high risk, tamoxifen decreased the risk of developing breast cancer by 49% (from 43.4 to 22 per 1000 women) after a median follow-up of nearly 6 years. Tamoxifen also reduced bone fractures; a small increase in risk of endo­ metrial cancer, stroke, pulmonary emboli, and deep vein thrombosis was noted. The International Breast Cancer Intervention Study (IBIS-I) and the Italian Randomized Tamoxifen Prevention Trial also demon­ strated reductions in breast cancer incidence with tamoxifen use. A trial comparing tamoxifen with another selective estrogen receptor modulator, raloxifene, performed in postmenopausal women showed that raloxifene is comparable to tamoxifen in cancer prevention but without the risk of endometrial cancer. Raloxifene was associated with a smaller reduction in invasive breast cancers and a trend toward more noninvasive breast cancers, but fewer thromboembolic events than tamoxifen; the drugs are similar in risks of other cancers, fractures, ischemic heart disease, and stroke. Both tamoxifen and raloxifene (the latter for postmenopausal women only) have been approved by the U.S. Food and Drug Administration (FDA) for reduction of breast cancer in women at high risk for the disease (1.66% risk at 5 years based on the Gail risk model: http://www.cancer.gov/bcrisktool/). Because the aromatase inhibitors (anastrozole, exemestane, and letrozole) are even more effective than tamoxifen in adjuvant breast cancer treatment, it has been hypothesized that they would be more effective in breast cancer prevention. A randomized, placebocontrolled trial of exemestane reported a 65% relative reduction (from 5.5 to 1.9 per 1000 women) in the incidence of invasive breast cancer in women at elevated risk after a median follow-up of about 3 years. Common adverse effects included arthralgias, hot flashes, fatigue, and insomnia. No trial has directly compared aromatase inhibitors with selective estrogen receptor modulators for breast cancer chemoprevention. ■ ■CHEMOPREVENTION OF PROSTATE CANCER Finasteride and dutasteride are 5-α-reductase inhibitors. They inhibit conversion of testosterone to dihydrotestosterone (DHT), a potent stimulator of prostate cell proliferation. The Prostate Cancer Preven­ tion Trial (PCPT) randomly assigned men age 55 years or older at average risk of prostate cancer to finasteride or placebo. All men in the trial were being regularly screened with prostate-specific antigen (PSA) levels and digital rectal examination. After 7 years of therapy, the overall incidence of prostate cancer was 18.4% in the finasteride arm, compared with 24.4% in the placebo arm, a statistically signifi­ cant reduction. However, the finasteride group had more patients with tumors of Gleason score 7 and higher compared with the placebo arm (6.4 vs 5.1%). Long-term (10–15 years) follow-up did not reveal any statistically significant differences in overall or prostate cancer–specific mortality between all men in the finasteride and placebo arms or in men diagnosed with prostate cancer, but the power to detect a differ­ ence was limited. CHAPTER 75 Prevention and Early Detection of Cancer Dutasteride has also been evaluated as a preventive agent for pros­ tate cancer. The Reduction by Dutasteride of Prostate Cancer Events (REDUCE) trial was a randomized double-blind trial in which ∼8200 men with an elevated PSA (2.5–10 ng/mL for men age 50–60 years and 3–10 ng/mL for men age 60 years or older) and negative prostate biopsy on enrollment received daily 0.5 mg of dutasteride or placebo. The trial found a statistically significant 23% relative risk reduction in the incidence of biopsy-detected prostate cancer in the dutasteride arm at 4 years of treatment (659 cases vs 858 cases, respectively). Overall, across years 1 through 4, no difference was seen between the arms in the number of tumors with a Gleason score of 7 to 10; however, during years 3 and 4, there was a statistically significant difference in tumors with Gleason score of 8 to 10 in the dutasteride arm (12 tumors vs 1 tumor, respectively). The finding of an apparent increased incidence of higher-grade tumors likely represents an increased sensitivity of PSA and digital rectal exam for high-grade tumors in men receiving 5-α-reductase inhibitors due to a decrease in prostatic volume. Although detection bias may have accounted for the finding, a causative role cannot be conclusively dismissed. These agents are therefore not FDA-approved for prostate cancer prevention. Because all men in both the PCPT and REDUCE trials were being screened and because screening approximately doubles the rate of prostate cancer, it is not known if finasteride or dutasteride decreases the risk of prostate cancer in men who are not being screened or simply reduces the risk of non-life-threatening cancers detectable by screening. Several favorable laboratory and observational studies led to the formal evaluation of selenium and α-tocopherol (vitamin E) as poten­ tial prostate cancer preventives. The Selenium and Vitamin E Cancer Prevention Trial (SELECT), after a median follow-up of 7 years, found a trend toward an increased risk of developing prostate cancer for men taking vitamin E alone as compared to placebo (hazard ratio 1.17; 95% confidence interval, 1.004–1.36). ■ ■VACCINES AND CANCER PREVENTION A number of infectious agents cause cancer. Hepatitis B and C viruses are linked to liver cancer; some HPV strains are linked to cervical, anal, and oropharyngeal cancer; and Helicobacter pylori is associated with gastric adenocarcinoma and gastric lymphoma. Vaccines to protect against these agents may therefore reduce the risk of their associated cancers. The hepatitis B vaccine is effective in preventing hepatitis and hepa­ tomas due to chronic hepatitis B infection. A nonavalent HPV vaccine (covering strains 6, 11, 16, 18, 31, 33, 45, 52, and 58) is available for use in the United States. HPV types 6 and 11 cause genital papillomas. The remaining HPV types cause cervical and anal cancer; reduction in HPV types 16 and 18 alone could theoreti­ cally prevent >70% of cervical cancers worldwide. For individuals not previously infected with these HPV strains, the vaccine demonstrates high efficacy in preventing persistent strain-specific HPV infections. Studies also confirm the vaccine’s ability to prevent preneoplastic lesions (cervical or anal intraepithelial neoplasia [CIN/AIN] I, II, and III). The vaccine does not appear to impact preexisting infections. A two-dose schedule is currently recommended in the United States for females and males age 9–14 years; teens and young adults who start the series between 15 and 26 years are recommended to receive three doses of the vaccine. However, observational studies suggest similar efficacy with a single dose in young girls, and a large randomized trial is cur­ rently comparing one to two doses. SURGICAL PREVENTION OF CANCER Some organs in some individuals are at such high risk of developing cancer that surgical removal of the organ at risk may be considered. Women with severe cervical dysplasia are treated with laser or loop electrosurgical excision or conization. Colectomy may be used to prevent colon cancer in patients with familial polyposis or ulcerative colitis. PART 4 Oncology and Hematology Prophylactic bilateral mastectomy may be chosen for breast can­ cer prevention among women with high-risk genetic predisposition to breast cancer. In a prospective series of 139 women with BRCA1 and BRCA2 mutations, at 3 years, no cases of breast cancer had been diagnosed in those opting for surgery (n = 76), but eight of 63 patients in the surveillance group had developed breast cancer. A larger retro­ spective cohort study reported three patients developed breast cancer after prophylactic mastectomy compared with an expected incidence of 30–53 cases. Postmastectomy breast cancer–related deaths were 81–94% lower in high-risk women compared with sister controls and 100% lower in moderate-risk women when compared with expected rates. Prophylactic salpingo-oophorectomy may also be employed for the prevention of ovarian and breast cancers among high-risk women. A prospective cohort study evaluating the outcomes of BRCA mutation carriers demonstrated a statistically significant association between prophylactic salpingo-oophorectomy and a reduced incidence of ovar­ ian or primary peritoneal cancer (36% relative risk reduction, or a 4.5% absolute difference). Studies of prophylactic oophorectomy for prevention of breast cancer in women with genetic mutations have shown relative risks of approximately 0.50; the risk reduction may be greatest for women hav­ ing the procedure at younger (i.e., <45–50) ages. The observation that most high-grade serous “ovarian cancers” actually arise in the fallopian tube fimbria raises the possibility that this lethal subtype may be pre­ vented by ovary-sparing salpingectomy. Formal testing of this hypoth­ esis is important because an emulated target trial (i.e., study design principles of an randomized controlled trial applied to observational data to estimate causal effects) demonstrated associations between bilateral salpingo-oophorectomy during benign hysterectomy and an increased risk for cardiovascular disease when done in premenopausal women and a trend toward increased 10-year mortality in all ages (with statistical significance in perimenopausal women). All of the evidence concerning the use of prophylactic mastectomy and salpingo-oophorectomy for prevention of breast and ovarian can­ cer in high-risk women has been observational; such studies are prone to a variety of biases, including case selection bias, family relationships between patients and controls, and inadequate information about hormone use. Thus, they may give an overestimate of the magnitude of benefit. ■ ■CANCER SCREENING Screening is a means of early detection in asymptomatic individuals, with the goal of decreasing morbidity and mortality. While screening can potentially reduce disease-specific deaths and has been shown to do so in cervical, colon, lung, and breast cancer, it is also subject to several biases that can suggest a benefit when there is none. Biases can even mask net harm. Early detection does not in itself confer benefit. Cause-specific mortality, rather than survival after diagnosis, is the preferred endpoint (see below). Because screening is done on asymptomatic, healthy persons, it should offer substantial likelihood of benefit that outweighs harm. Screening tests and their appropriate use should be carefully evaluated before their use is widely encouraged in screening programs. The Accuracy of Screening  A screening test’s accuracy or ability to discriminate disease is described by four indices: sensitivity, specificity, positive predictive value, and negative predictive value (Table 75-2). Sensitivity, also called the true-positive rate, is the proportion of per­ sons with the disease who test positive in the screen (i.e., the ability of the test to detect disease when it is present). Specificity, or 1 minus the false-positive rate, is the proportion of persons who do not have the disease who test negative in the screening test (i.e., the ability of a test to correctly indicate that the disease is not present). The positive predictive value is the proportion of persons who test positive and who actually have the disease. Similarly, negative predictive value is the proportion testing negative who do not have the disease. The sensitivity and speci­ ficity of a test are relatively independent of the underlying prevalence (or risk) of the disease in the population screened, but the predictive values depend strongly on the prevalence of the disease. Screening is most beneficial, efficient, and economical when the target disease is common in the population being screened. Specific­ ity is at least as important to the ultimate feasibility and success of a screening test as sensitivity. Potential Biases of Screening Tests  Common biases of screen­ ing are lead time, length-biased sampling (and related overdiagnosis), and selection. These biases can make a screening test seem beneficial when it is not (or even causes net harm). Whether beneficial or not, screening can create the false impression of an epidemic by increasing the number of cancers diagnosed. It can also produce a shift in the pro­ portion of patients diagnosed at an early stage (even without a reduc­ tion in absolute incidence of late-stage disease) and inflate survival statistics without reducing mortality (i.e., the number of deaths from a given cancer relative to the number of those at risk for the cancer in TABLE 75-2  Assessment of the Value of a Diagnostic Testa   CONDITION PRESENT CONDITION ABSENT Positive test a b Negative test c d a = true positive     b = false positive     c = false negative     d = true negative     Sensitivity The proportion of persons with the condition who test positive: a/(a + c) Specificity The proportion of persons without the condition who test negative: d/(b + d) Positive predictive value (PPV) The proportion of persons with a positive test who have the condition: a/(a + b) Negative predictive value The proportion of persons with a negative test who do not have the condition: d/(c + d) Prevalence, sensitivity, and specificity determine PPV PPV prevalence sensitivity (prevalence sensitivity) (1 prevalence)(1 specificity) = × × + − − aFor diseases of low prevalence, such as cancer, poor specificity has a dramatic adverse effect on PPV such that only a small fraction of positive tests are true positives. the total population). In such a case, the apparent duration of survival (measured from date of diagnosis) increases without lives being saved or life expectancy changed. Lead-time bias occurs whether or not a test influences the natural history of the disease; the patient is merely diagnosed at an earlier date. Survival appears increased even if life is not prolonged. The screen­ ing test only prolongs the time the subject is aware of the disease and spends as a cancer patient. Length-biased sampling occurs because screening tests generally can more easily detect slow-growing, less aggressive cancers than fast-growing cancers. Cancers diagnosed due to the onset of symp­ toms between scheduled screenings are on average more aggressive, and treatment outcomes are not as favorable. An extreme form of length bias sampling is termed overdiagnosis, the detection of “pseudo disease.” The reservoir of some slow-growing tumors is large. Many of these tumors fulfill the histologic criteria of cancer but will never become clinically significant or cause death during the patient’s remaining life span. This problem is compounded by the fact that the most common cancers appear most frequently at ages when competing causes of death are more frequent. Selection bias occurs because the population most likely to seek screening often differs from the general population to which the screening test might be applied. In general, volunteers for studies are more health conscious and likely to have a better prognosis or lower mortality rate irrespective of the screening result. This is termed the healthy volunteer effect. Potential Drawbacks of Screening  Risks associated with screen­ ing include harm caused by the screening intervention itself, harm due to the further investigation of persons with positive tests (both true and false positives), and harm from the treatment of persons with a truepositive result, whether or not life is extended by treatment (e.g., even if a screening test reduces relative cause-specific mortality by 15–30%, 70–85% of those diagnosed still go on to die of the target cancer). The diagnosis and treatment of cancers that would never have caused medi­ cal problems (i.e., overdiagnosis) can lead to the harm of unnecessary treatment (i.e., overtreatment) and give patients the anxiety of a cancer diagnosis. The psychosocial impact of cancer screening can be substan­ tial when applied to the entire population. Assessment of Screening Tests  Good clinical trial design can offset some biases of screening and directly identify the balance of risks and benefits of a screening test. A randomized controlled screening trial with cause-specific mortality as the endpoint provides the stron­ gest support for a screening intervention. Overall mortality should also be reported to detect an adverse effect of screening and treatment on other disease outcomes (e.g., cardiovascular disease, treatmentinduced cancers). In a randomized trial, two like populations are ran­ domly established. One is given the usual standard of care (which may be no screening at all) and the other receives the screening intervention being assessed. Efficacy for the population studied is established when the group receiving the screening test has a lower cause-specific mor­ tality rate than the control group. Studies showing a reduction in the incidence of advanced-stage disease, improved survival, or a stage shift are weaker (and possibly misleading) evidence of benefit. These latter criteria are early indicators but not sufficient to definitively establish the value of a screening test. Although a randomized, controlled screening trial provides the strongest evidence to support a screening test, it is not perfect. Unless the trial is population-based, it does not remove the question of gen­ eralizability to the target population. Screening trials generally involve thousands of persons and last for years. Less definitive study designs are therefore used to assess the effectiveness of a screening test of proven efficacy in actual practice. However, every nonrandomized study design is subject to strong confounders. In descending order of strength, evidence may also be derived from the findings of internally controlled trials using intervention allocation methods other than randomization (e.g., allocation by birth date, date of clinic visit); the findings of analytic observational studies; or the results of multiple time series studies with or without the intervention. Screening for Specific Cancers  Screening for cervical, colon, and breast cancer has the potential to be beneficial for certain age groups. Although these tests can reduce deaths from the cancer being screened for, meta-analyses of randomized trials have not shown that they affect all-cause mortality. Lung cancer screening can also reduce deaths in specific settings, depending on age and smoking history. Spe­ cial surveillance of those at high risk for a specific cancer because of a family history or a genetic risk factor may be prudent, but few studies have assessed the effect on mortality. A number of organizations have considered whether or not to endorse routine use of certain screening tests. Because their perspectives have varied, they have arrived at dif­ ferent recommendations. The American Cancer Society (ACS) and the U.S. Preventive Services Task Force (USPSTF) publish screening guide­ lines (Table 75-3); the American Academy of Family Practitioners (AAFP) often follows/endorses the USPSTF recommendations; and the American College of Physicians (ACP) develops recommendations based on structured reviews of other organizations’ guidelines. BREAST CANCER  Breast self-examination, clinical breast examination by a caregiver, mammography, and magnetic resonance imaging (MRI) have all been variably advocated as useful screening tools. A number of trials suggest that annual or biennial screening with mammography in normal-risk women older than age 50 years decreases breast cancer mortality. In most, breast cancer–related mor­ tality rates were decreased by 15–30%. Experts disagree on whether average-risk women age 40–49 years should receive regular screening. The U.K. Age Trial, the only randomized trial of breast cancer screen­ ing to specifically evaluate the impact of mammography in women age 40–49 years, found no statistically significant difference in breast can­ cer mortality for screened women versus controls after about 22 years of follow-up (relative risk 0.88; 95% confidence interval, 0.74–1.03); however, <70% of women received screening in the intervention arm, potentially diluting the observed effect. A meta-analysis of nine large randomized trials showed an 8% relative reduction in breast cancer mortality (relative risk 0.92; 95% confidence interval, 0.75–1.02) from mammography screening for women age 39–49 years after 11–20 years of follow-up. This is equivalent to 3 breast cancer deaths prevented per 10,000 women over 10 years (although the result is not statistically significant). At the same time, nearly half of women age 40–49 years screened annually will have false-positive mammograms necessitating further evaluation, often including biopsy. Estimates of overdiagnosis range from 10 to 50% of diagnosed invasive cancers. CHAPTER 75 Prevention and Early Detection of Cancer In the United States, widespread screening over the past several decades has not been accompanied by a reduction in incidence of metastatic breast cancer despite a large increase in early-stage disease, suggesting a substantial amount of overdiagnosis at the population level. In addition, the substantial improvements in systemic therapy have likely decreased the impact of mammography and early detection on falling breast cancer mortality rates. Digital breast tomosynthesis is a newer method of breast cancer screening that reconstructs multiple x-ray images of the breast into superimposed “three-dimensional” slices. Although some evidence is available concerning the test characteristics of this modality, there are currently no data on its effects on health outcomes such as breast cancer–related morbidity, mortality, or overdiagnosis rates. A large randomized trial comparing standard digital mammography to tomo­ synthesis is in progress. No study of breast self-examination has shown it to decrease mortal­ ity. A randomized controlled trial of approximately 266,000 women in China demonstrated no difference in breast cancer mortality between a group that received intensive breast self-exam instruction and rein­ forcement/reminders and controls at 10 years of follow-up. However, more benign breast lesions were discovered and more breast biopsies were performed in the self-examination arm. Genetic screening for BRCA1 and BRCA2 mutations and other markers of breast cancer risk has identified a group of women at high risk for breast cancer. Unfortunately, when to begin and the optimal frequency of screening have not been defined. Mammography is less sensitive at detecting breast cancers in women carrying BRCA1 and TABLE 75-3  Screening Recommendations for Asymptomatic Subjects Not Known to Be at Increased Risk for the Target Conditiona CANCER TYPE TEST OR PROCEDURE USPSTF ACS Breast Self-examination “D”b (Not in current recommendations; from 2009) Women, all ages: No specific recommendation   Clinical examination Women ≥40 years: “I” (as a stand-alone without mammography) (Not in current recommendations; from 2009)   Mammography Women aged 40-74 years: Biennial screening mammography (“B”)     Women ≥75 years: “I”     Magnetic resonance imaging (MRI) “I” Women with >20% lifetime risk of breast cancer: Screen with MRI plus mammography annually       Women with 15–20% lifetime risk of breast cancer: Discuss option of MRI plus mammography annually       Women with <15% lifetime risk of breast cancer: Do not screen annually with MRI Cervical Pap test (cytology) Women <21 years: “D” Women 21–29 years: Screen with cytology alone every 3 years (“A”) Women 30–65 years: Screen with cytology alone every 3 years, or with co-testing (HPV testing + cytology) every 5 years (two of three options, see HPV test below) (“A”) Women >65 years, with adequate, normal prior Pap screenings: “D” Women after total hysterectomy for noncancerous causes: “D” PART 4 Oncology and Hematology   HPV test Women <30 years: Do not use HPV testing for cervical cancer screening Women 30–65 years: Screen with HPV testing alone or in combination with cytology every 5 years (two of three options, see Pap test above) (“A”) Women >65 years, with adequate, normal prior Pap screenings: “D” Women after total hysterectomy for noncancerous causes: “D” Colorectal Overall Adults 50–75 years: “A” Screen for colorectal cancer Adults 45–50 years: “B” Screen for colorectal cancer Adults 76–85 years: “C” Selectively offer screening for colorectal cancer; consider the patient’s overall health, prior screening history, and preferences   Sigmoidoscopy Every 5 years; modeling suggests improved benefit if performed every 10 years in combination with annual FIT   Fecal occult blood testing (FOBT) Every year Adults ≥45 years: Every year   Colonoscopy Every 10 years Adults ≥45 years: Every 10 years   Fecal DNA testing At least every 3 years Adults ≥45 years: Every 3 years   Fecal immunochemical testing (FIT) Every year Adults ≥45 years: Every year   Computed tomography (CT) colonography Every 5 years Adults ≥45 years: Every 5 years Lung Low-dose CT scan Adults 50–80 years, with a ≥20 pack-year smoking history, still smoking or have quit within past 15 years, annually: “B” Discontinue once a person has not smoked for 15 years or develops a health problem that substantially limits life expectancy or the ability to have curative lung surgery Women, all ages: Do not recommend Women 40–44 years: Provide the opportunity to begin annual screening Women 45–54 years: Screen annually Women ≥55 years: Transition to biennial screening or have the opportunity to continue annual screening Women ≥40 should continue screening mammography as long as their overall health is good and they have a life expectancy of 10 years or longer Women <21 years: No screening Women 21–29 years: Screen every 3 years Women 30–65 years: Screen with co-testing (HPV testing + cytology) every 5 years or cytology alone every 3 years (see HPV test below) Women >65 years: No screening following adequate negative prior screening Women after total hysterectomy for noncancerous causes: Do not screen Women <30 years: Do not use HPV testing for cervical cancer screening Women 30–65 years: Preferred approach to screen with HPV and cytology co-testing every 5 years (see Pap test above) Women >65 years: No screening following adequate negative prior screening Women after total hysterectomy for noncancerous causes: Do not screen Adults ≥45–75 years: Screen for colorectal cancer with either a high-sensitivity stool-based test or a structural (visual) examination (≥45 years, qualified recommendation; ≥50 years, strong recommendation). Adults 76–85 years: Individualize screening based on patient preferences, life expectancy, health status, and prior screening history (qualified recommendation). Adults >85 years: Discourage screening (qualified recommendation). Every 5 years Adults ≥45 years: Every 5 years Men and women, 50–80 years, with ≥20 pack-year smoking history, current or former smoker, annually: Discuss benefits, limitations, and harms of screening; offer smoking cessation counseling and connection to resources where relevant. Individuals with comorbid conditions that substantially limit life expectancy should not be screened. (Continued) TABLE 75-3  Screening Recommendations for Asymptomatic Subjects Not Known to Be at Increased Risk for the Target Conditiona CANCER TYPE TEST OR PROCEDURE USPSTF ACS Ovarian CA-125 Transvaginal ultrasound Women, all ages: “D” Women with a high-risk hereditary cancer syndrome: No recommendation Prostate Prostate-specific antigen (PSA) Men 55–69 years: The decision to undergo periodic PSAbased screening should be an individual one. Men should have an opportunity to discuss the potential benefits and harms of screening with their clinician. Clinicians should not screen men who do not express a preference for screening (“C”) Men ≥70 years: “D”   Digital rectal examination (DRE) No individual recommendation As for PSA; if men decide to be tested, they should have the PSA blood test with or without a rectal exam. Skin Complete skin examination by clinician or patient Adults, all ages: “I” No guidelines aSummary of the screening procedures recommended for the general population by the USPSTF and the ACS. These recommendations refer to asymptomatic persons who are not known to have risk factors, other than age or gender, for the targeted condition. bUSPSTF lettered recommendations are defined as follows: “A”: The USPSTF recommends the service because there is high certainty that the net benefit is substantial; “B”: The USPSTF recommends the service because there is high certainty that the net benefit is moderate or moderate certainty that the net benefit is moderate to substantial; “C”: The USPSTF recommends selectively offering or providing this service to individual patients based on professional judgment and patient preferences; there is at least moderate certainty that the net benefit is small; “D”: The USPSTF recommends against the service because there is moderate or high certainty that the service has no net benefit or that the harms outweigh the benefits; “I”: The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of the service. Table only includes final, not draft, recommendations, from the USPSTF. Abbreviations: ACS, American Cancer Society; USPSTF, U.S. Preventive Services Task Force. BRCA2 mutations, possibly because such cancers occur in younger women, in whom mammography is known to be less sensitive. MRI screening may be more sensitive than mammography in women at high risk due to genetic predisposition or in women with very dense breast tissue, but specificity may be lower. An increase in overdiagnosis may accompany the higher sensitivity. The impact of MRI on breast cancer mortality with or without concomitant use of mammography has not been evaluated in a randomized controlled trial. CERVICAL CANCER  The cervical cancer mortality rate has fallen substantially since the widespread use of the Pap smear. Screening guidelines recommend regular Pap testing for all women who have reached the age of 21 (before this age, even in individuals that have begun sexual activity, screening may cause more harm than benefit). The recommended interval for Pap screening is 3 years. In all cases, screening more frequently adds little benefit but leads to important harms, including unnecessary procedures and overtreatment of tran­ sient lesions. With the onset of sexual activity comes the risk of sexual transmission of HPV, the fundamental etiologic factor for cervical can­ cer. Beginning at age 30, guidelines also include HPV testing with or without Pap smear. The screening interval for women who test normal using this approach may be lengthened to 5 years. An upper age limit at which screening ceases to be effective is not known, but women age 65 years with no abnormal results in the previ­ ous 10 years may choose to stop screening. Screening should be dis­ continued in women who have undergone a hysterectomy with cervical excision for noncancerous reasons. Although the efficacy of the Pap smear in reducing cervical cancer mortality has never been directly confirmed in a randomized, con­ trolled setting, a clustered randomized trial in India evaluated the impact of one-time cervical visual inspection and immediate colpos­ copy, biopsy, and/or cryotherapy (where indicated) versus counseling on cervical cancer deaths in women age 30–59 years. After 7 years of follow-up, the age-standardized rate of death due to cervical cancer was 39.6 per 100,000 person-years in the intervention group versus 56.7 per 100,000 person-years in controls. COLORECTAL CANCER  Digital rectal examination (DRE), stool-based testing (fecal occult blood testing [FOBT], fecal immunochemical tests [FITs], multitargeted stool DNA tests), blood-based testing (SEPT9), and optical testing (rigid and flexible sigmoidoscopy, colonoscopy, (Continued) Currently, there are no reliable screening tests for the early detection of ovarian cancer. For women at high risk of ovarian cancer, it has not been proven that using transvaginal ultrasound or serum CA-125 lowers their chances of dying from ovarian cancer. Starting at age 50, men at average risk and with a life expectancy of ≥10 years should talk to a doctor about the uncertainties, risks, and potential benefits of screening. If African American or have a father or brother who had prostate cancer before age 65, men should have this talk starting at age 45. For men with more than one firstdegree relative with prostate cancer diagnosed before age 65, have this talk starting at age 40. How often they are screened will depend on their PSA level. CHAPTER 75 Prevention and Early Detection of Cancer computed tomography [CT] colonography) have been considered for colorectal cancer screening. DRE is not an effective colorectal cancer screening test and is not recommended by any medical organization. Stool-Based Testing  A meta-analysis of five randomized controlled trials demonstrated a 22% relative reduction in colorectal cancer mortality after two to nine rounds of biennial FOBT at 30 years of follow-up; annual screening was shown to result in a greater mortality reduction in a single trial (a 32% relative reduction). However, only 2–10% of those with occult blood in the stool actually have cancer. The high false-positive rate of FOBT therefore leads to a large number of diagnostic follow-up colonoscopies. FITs have higher sensitivity for colorectal cancer than FOBT tests and have largely replaced FOBT in clinical practice. Limited evidence suggests FITs may not detect proximal colonic tumors at the same rate as distal ones. Multitargeted stool DNA testing (e.g., Cologuard) combines FIT with testing for altered DNA biomarkers that are shed into the stool. Although limited evidence demonstrates that it can have a higher single-test sensitivity for colorectal cancer than FIT alone, its specificity is lower, resulting in a higher number of false-positive tests and follow-up colonoscopies. No studies have yet evaluated its effects on colorectal cancer incidence, morbidity, or mortality. Blood-Based Testing  A blood test for the methylated SEPT9 gene associ­ ated with colorectal cancer is available. Case-control studies suggest that it has a lower sensitivity and specificity than the FIT stool test. It also is more costly, and it is not recommended as a first-line screening test. Optical Testing  Two meta-analyses of five randomized controlled trials of sigmoidoscopy found an 18% relative reduction in colorectal cancer incidence and a 28% relative reduction in colorectal cancer mortality. Participant ages ranged from 50 to 74 years, with follow-up ranging from 6 to 13 years. Diagnosis of adenomatous polyps by sigmoidoscopy should lead to evaluation of the entire colon with colonoscopy. The most efficient interval for screening sigmoidoscopy is unknown, but an interval of 5 years is often recommended. Case-control studies suggest that intervals of up to 15 years may confer benefit; a randomized trial in the U.K. demonstrated colorectal cancer mortality reduction with one-time screening. One-time colonoscopy detects ∼25% more advanced lesions (pol­ yps >10 mm, villous adenomas, adenomatous polyps with high-grade dysplasia, invasive cancer) than one-time FOBT with sigmoidoscopy; comparative programmatic performance of the two modalities over time is not known. Perforation rates are about 4/10,000 for colonos­ copy and 1/10,000 for sigmoidoscopy. Debate continues on whether colonoscopy is too expensive and invasive and whether sufficient provider capacity exists to be recommended as the preferred screening tool in standard-risk populations. Some observational studies suggest that efficacy of colonoscopy to decrease colorectal cancer mortality is higher on the left side of the colon than the right. CT colonography, if done at expert centers, appears to have a sen­ sitivity for polyps ≥6 mm, comparable to colonoscopy. However, the rate of extracolonic findings of abnormalities of uncertain significance that must nevertheless be worked up is high (∼5–37%); the long-term cumulative radiation risk of repeated colonography screenings is also a concern. LUNG CANCER  Chest x-ray and sputum cytology have been evaluated in several randomized lung cancer screening trials. The most recent and largest (n = 154,901) of these, a component of the Prostate, Lung, Colorectal, and Ovarian (PLCO) cancer screening trial, found that, compared with usual care, annual chest x-ray did not reduce the risk of dying from lung cancer (relative risk 0.99; 95% confidence interval, 0.87–1.22) after 13 years. However, it showed evidence of overdiagno­ sis associated with chest x-ray. Low-dose CT has also been evaluated in several randomized trials. The largest and longest of these, the National Lung Screening Trial (NLST), was a randomized controlled trial of screening for lung cancer in ∼53,000 persons age 55–74 years with a 30+ pack-year smoking history. It demonstrated a statistically significant reduction of about 3 fewer deaths per 1000 people screened with CT compared to chest x-ray after 12 years. Harms include the potential radiation risks associated with multiple scans, the discovery of incidental findings of unclear significance, and a high rate of falsepositive test results. Both incidental findings and false-positive tests can lead to invasive diagnostic procedures associated with anxiety, complications, and expense. The NLST was performed at experienced screening centers, and the balance of benefits and harms may differ in the community setting at less experienced centers. PART 4 Oncology and Hematology OVARIAN CANCER  Adnexal palpation, transvaginal ultrasound (TVUS), and serum CA-125 assay have been considered for ovarian cancer screening. A large randomized, controlled trial has shown that an annual screening program of TVUS and CA-125 in average-risk women does not reduce deaths from ovarian cancer (relative risk 1.21; 95% confidence interval, 0.99–1.48). Adnexal palpation was dropped early in the study because it did not detect any ovarian cancers that were not detected by either TVUS or CA-125. A second large, random­ ized trial used a two-stage screening approach incorporating a risk of ovarian cancer algorithm that determined whether additional testing with CA-125 or TVUS was required. At 14 years of follow-up, there was no statistically significant reduction in ovarian cancer deaths. The risks and costs associated with the high number of false-positive results are impediments to routine use of these modalities for screening. In the PLCO trial, 10% of participants had a false-positive result from TVUS or CA-125, and one-third of these women underwent a major surgical procedure; the ratio of surgeries to screen-detected ovarian cancer was approximately 20:1. In September 2016, the FDA issued a safety com­ munication recommending against using any ovarian cancer screening test, including the algorithm for risk of the cancer. PROSTATE CANCER  The most common prostate cancer screening modalities are digital rectal exam (DRE) and serum PSA assay. An emphasis on PSA screening has made prostate cancer the most com­ mon nonskin cancer diagnosed in American males. This disease is prone to lead-time bias, length bias, and overdiagnosis, and substantial debate continues among experts as to whether screening should be offered unless the patient specifically asks to be screened. Virtually all organizations stress the importance of informing men about the uncer­ tainty regarding screening efficacy and the associated harms. Prostate cancer screening clearly detects many asymptomatic cancers, but men older than age 50 years have a high prevalence of clinically insignificant prostate cancers (about 30–50% of men, increasing further as men age). The ability to distinguish tumors that are lethal but still curable from those that pose little or no threat to health is limited, although evidence suggests multiparametric MRI may aid decision-making. Randomized trials indicate that the effect of PSA screening on pros­ tate cancer mortality across a population is, at best, small. Two major trials have been published. The PLCO Cancer Screening Trial was a multicenter U.S. trial that randomized almost 77,000 men age 55–74 years to receive either annual PSA testing for 6 years or usual care. At 13 years of follow-up, no statistically significant difference in the num­ ber of prostate cancer deaths was noted between the arms (rate ratio 1.09; 95% confidence interval, 0.87–1.36). More than half of men in the control arm received at least one PSA test during the trial, which may have diluted a small effect. The European Randomized Study of Screening for Prostate Cancer (ERSPC) was a multinational study that randomized ∼182,000 men between age 50 and 74 years (with a predefined “core” screening group of men age 55–69 years) to receive PSA testing or no screen­ ing. Recruitment and randomization procedures, as well as actual frequency of PSA testing, varied by country. After a median follow-up of 15.5 years, a 20% relative reduction in the risk of prostate cancer death in the screened arm was noted in the “core” screening group. The trial found that 570 men (95% confidence interval, 380–1137 men) would need to be invited to screening, and 18 cases of prostate cancer detected, to avert 1 death from prostate cancer. There was an unexplained imbalance in treatment between the two study arms, with a higher proportion of men with clinically localized cancer receiving radical prostatectomy in the screening arm and receiving it at experi­ enced referral centers. Screening must be linked to effective therapy to have any benefit. Two trials conducted after the initiation of widespread PSA testing did not find a substantial decrease in prostate cancer deaths in control arms of “watchful waiting” or monitoring (i.e., no curative treatment) compared to radical prostatectomy or radiation therapy. Prostate cancer–specific survival was very good (about 99%) and nearly identi­ cal at a median follow-up of 10 years. Treatments for low-stage prostate cancer, such as surgery and radiation therapy, can cause substantial morbidity, including impotence and urinary incontinence. SKIN CANCER  Visual examination of all skin surfaces by the patient or by a health care provider is used in screening for basal and squamous cell cancers and melanoma. No prospective randomized study has been performed to look for a mortality decrease. Unfortunately, screening is associated with a substantial rate of overdiagnosis. MULTICANCER EARLY DETECTION TESTS  Multicancer early detection (MCED) tests look for multiple biomarkers in blood that are either directly released or induced by cancer cells. One potential purpose of these tests could be to screen for multiple cancers at the same time in asymptomatic people. However, most of the evidence at present for these tests comes from people who have already been diagnosed with cancer (a fundamentally different population); additionally, no data are available on health outcomes associated with using MCED tests for cancer screening. ■ ■FURTHER READING Fenton JJ et al: Prostate-specific antigen-based screening for prostate cancer: Evidence report and systematic review for the U.S. Preventive Services Task Force. JAMA 319:1914, 2018. Jonas DE et al: Screening for lung cancer with low-dose computed tomography: Updated Evidence report and systematic review for the US Preventive Services Task Force. JAMA 325:971, 2021. Kramer BS, Croswell JM: Cancer screening: The clash of science and intuition. Annu Rev Med 60:125, 2009. Lin JS et al: Screening for colorectal cancer: Updated evidence report and systematic review for the US Preventive Services Task Force. JAMA 325:1978, 2021. # 05 - 76 Cancer Genetics ### 76 Cancer Genetics Manson JE et al: Vitamin D supplements and prevention of cancer and cardiovascular disease. N Engl J Med 380:33, 2019. Mcneil JJ et al: Effect of aspirin on all-cause mortality in the healthy elderly. N Engl J Med 379:1519, 2018. Melnikow J et al: Screening for cervical cancer with high-risk human papillomavirus testing: Updated evidence report and systematic review for the US Preventive Services Task Force. JAMA 320:687, 2018. Welch HG et al: Epidemiologic signatures in cancer. N Engl J Med 384:14, 2019. Woloshin S et al: Breast-cancer mortality trends in four countries with varied screening practices. N Engl J Med 389:1061, 2023. Zeraatkar D et al: Effect of lower versus high red meat intake on cardiometabolic and cancer outcomes: A systematic review of ran­ domized trials. Ann Intern Med 171:721, 2019. Fred Bunz, Bert Vogelstein Cancer Genetics CANCER IS A GENETIC DISEASE Cancer arises through a series of somatic alterations in DNA that result in unrestrained cellular proliferation. Most of these alterations involve subtle sequence changes in DNA (i.e., mutations). The somatic mutations may originate as a consequence of random replication errors or exposure to carcinogens (e.g., radiation) and can be exacerbated by faulty DNA repair processes. While most cancers arise sporadically, clustering of can­ cers occurs in families that carry a germline mutation in a cancer gene. HISTORICAL PERSPECTIVE The idea that cancer progression is driven by sequential somatic muta­ tions in specific genes has only gained general acceptance in the past 30 years. Before the advent of the microscope, cancer was believed to be composed of aggregates of mucus or other noncellular matter. By the middle of the nineteenth century, it became clear that tumors were masses of cells and that these cells arose from the normal cells of the tissue from which the cancer originated. The molecular basis for the uncontrolled proliferation of cancer cells was to remain a mystery for another century. During that time, a number of theories for the origin of cancer were postulated. The great biochemist Otto Warburg proposed the combustion theory of cancer, which stipulated that cancer was due to abnormal oxygen metabolism. Others believed that all cancers were caused by viruses and that cancer was in fact a contagious disease. In the end, observations of cancer occurring in chimney sweeps, studies of x-rays, and the overwhelming data demonstrating cigarette smoke as a causative agent in lung cancer, together with Ames’s work on chemical mutagenesis, were consistent with the idea that cancer originated through changes in DNA. However, it was not until the somatic mutations responsible for cancer were identified at the molec­ ular level that the genetic basis of cancer was definitively established. Although the viral theory of cancer did not prove to be generally accurate (with exceptions such as human papillomaviruses, which can cause cervical and other cancers), the study of retroviruses led to the discovery of the first human oncogenes in the late 1970s. Oncogenes are one of the two major classes of cancer driver genes. The study of families with genetic predisposition to cancer was instrumental to the discovery of the other major class of cancer driver genes, called tumorsuppressor genes. Current technologies permit the sequence analysis of entire cancer genomes and provide a comprehensive view of the genetic changes that cause tumors to arise and become malignant. The field that studies the various types of mutations, as well as the consequences of these mutations in tumor cells, is now known as cancer genetics. THE CLONAL ORIGIN AND MULTISTEP NATURE OF CANCER Nearly all cancers originate from a single cell; this clonal origin is a critical discriminating feature between neoplasia and hyperplasia. Multiple cumulative mutational events are invariably required for the progression of a tumor from normal to fully malignant phenotype. The process can be seen as Darwinian microevolution in which, at each successive step, the mutated cells gain a growth advantage resulting in the expansion of a neoplastic clone (Fig. 76-1). Based on observa­ tions of cancer frequency increases during aging, the epidemiologists Armitage and Doll and Nordling independently proposed that cancer is a result of three discrete cellular changes. Remarkably, this early model has been validated by extensive sequencing of cancer genomes. These studies revealed that just three causal mutations are required for the development of several of the most common cancers. Overall, it is currently believed that most common solid tumors require a minimum of three mutated cancer driver genes (either oncogenes or tumorsuppressor genes) for their development. One or two mutations are sufficient for benign tumorigenesis, but not for the invasive capacity that distinguishes cancers from benign tumors. Less common tumors, such as liquid tumors (leukemias or lymphomas), sarcomas, and childhood tumors, appear to require only two driver gene alterations for malignancy. Note that a cancer driver gene is best defined as one containing a mutation that increases the selective growth advantage of the cell containing it. Normally, cell birth and cell death are in perfect equilibrium; every time a cell is born, another in the same lineage dies. Cancer driver gene mutations alter this equilibrium, so that more cells are born than die. The imbalance is often slight, so that the difference between cell birth and cell death can be less than 1%. This explains, in combination with the low rate of mutation, why tumorigenesis—the journey from a normal cell to a typical malignant, solid tumor—often takes decades. CHAPTER 76 Cancer Genetics We now know the precise nature of the genetic alterations respon­ sible for nearly all malignancies and are beginning to understand how these alterations promote the distinct stages of tumor growth. The prototypical example is colon cancer, in which analyses of genomes from the entire spectrum of neoplastic growths—from normal colon Initiation Expansion Invasion FIGURE 76-1  Multistep clonal development of malignancy. In this diagram, a series of three cumulative mutations, each with a modest growth advantage acting alone, eventually results in a malignant tumor. Note that not all such alterations result in progression. The actual number of cumulative mutations necessary to transform from the normal to the malignant state has been estimated to be three for several of the most common types of cancer. (Adapted and modified from PC Nowell: The clonal evolution of tumor cell populations. Science 194:23, 1976.) Microsatellite Instability (MIN) or Chromosomal Instability (CIN) SMAD4 or TGFb II inactivation TP53 inactivation APC inactivation or b-catenin activation KRAS or BRAF activation Early adenoma Late adenoma Carcinoma Metastasis Normal epithelium Initiation Expansion Invasion FIGURE 76-2  Progressive somatic mutational steps in the development of colon carcinoma. The accumulation of alterations in a number of different genes results in the progression from normal epithelium through adenoma to full-blown carcinoma. Genetic instability (microsatellite or chromosomal) accelerates the progression by increasing the likelihood of mutation at each step. Patients with familial polyposis are already one step into this pathway because they inherit a germline alteration of the APC gene. TGF, transforming growth factor. epithelium through adenoma to carcinoma—have identified mutations that are highly characteristic of each type of lesion (Fig. 76-2). PART 4 Oncology and Hematology TWO TYPES OF CANCER GENES: ONCOGENES AND TUMOR-SUPPRESSOR GENES Oncogenes and tumor-suppressor genes exert their effects on tumor growth through their ability to determine cell fates, influence cell sur­ vival, and contribute to genome maintenance. The underlying molecu­ lar mechanisms can be extremely complex. While tightly regulated in normal cells, oncogenes acquire mutations that typically relieve this control and lead to increased activity of the gene products. This activat­ ing mutational event occurs in a single allele. In contrast, the normal function of tumor-suppressor genes is usually to restrain cell growth, and this function is lost in cancer. Because of the diploid nature of mammalian cells, both alleles must be inactivated for a cell to com­ pletely lose the function of a tumor-suppressor gene. Thus, two genetic events are required to inactivate a tumor-suppressor gene, while only one genetic event is required to activate an oncogene. A subset of tumor-suppressor genes controls the ability of the cell to maintain the integrity of its genome. Cells with a deficiency in these genes acquire an increased number of mutations throughout their genomes, including those in oncogenes and tumor-suppressor genes. This “mutator” phenotype was first hypothesized by Loeb to explain how the multiple rare mutational events required for tumorigenesis can occur in the lifetime of an individual. A mutator phenotype under­ lies several forms of cancer, such as those associated with deficiencies in DNA mis­ match repair. The great majority of cancers do not harbor repair deficiencies, and their rate of mutation is similar to that observed in normal cells. Many of these cancers, however, appear to harbor a different kind of genetic instability, affecting the loss or gains of whole chromosomes or large parts thereof (as explained in more detail below). TABLE 76-1  Oncogenes Commonly Altered in Human Cancers ONCOGENE FUNCTION ALTERATION IN CANCER NEOPLASM AKT1 Serine/threonine kinase Point mutation Skin BRAF Serine/threonine kinase Point mutation Melanoma, thyroid, colorectal CCND1 Cell cycle progression Amplification Esophageal, head and neck CTNNB1 Signal transduction Point mutation Colon, liver, uterine, melanoma EGFR Signal transduction Point mutation Lung FLT3 Signal transduction Point mutation AML IDH1 Chromatin modification Point mutation Glioma MDM2 Inhibitor of p53 Amplification Sarcoma, glioma MDM4 Inhibitor of p53 Amplification Breast MYC Transcription factor Amplification Prostate, ovarian, breast, liver, pancreatic ONCOGENES IN HUMAN CANCER Work by Peyton Rous in the early 1900s revealed that a chicken sarcoma could be transmitted from animal to animal in cellfree extracts, suggesting that cancer could be induced by an agent acting positively to MYCL1 Transcription factor Amplification Ovarian, bladder MYCN Transcription factor Amplification Neuroblastoma PIK3CA Phosphoinositol-3-kinase Point mutation Multiple cancers KRAS GTPase Point mutation Pancreatic, colorectal, lung NRAS GTPase Point mutation Melanoma Abbreviation: AML, acute myeloid leukemia. promote tumor formation. The agent responsible for the transmission of the cancer was a retrovirus (Rous sarcoma virus [RSV]), and the oncogene responsible was identified 75 years later as V-SRC. Other oncogenes were also discovered through their presence in the genomes of retroviruses that are capable of causing cancers in chickens, mice, and rats. The nonmutated cellular homologues of these viral genes are called proto-oncogenes and are often targets of mutation or aberrant regula­ tion in human cancer. Whereas many oncogenes were discovered on the basis of their presence in retroviruses, other oncogenes, particularly those involved in translocations characteristic of par­ ticular leukemias and lymphomas, were identi­ fied through genomic approaches. Investigators cloned the sequences surrounding the chromo­ somal translocations observed cytogenetically and identified the genes activated at the breakpoints (see below). Some of these were oncogenes previ­ ously found in retroviruses (like ABL, involved in chronic myeloid leukemia [CML]), whereas others were new (like BCL2, involved in B-cell lymphoma). In the normal cel­ lular environment, proto-oncogenes have crucial roles in cell prolifera­ tion and differentiation. Table 76-1 is a partial list of oncogenes known to be involved in human cancer. The normal growth and differentiation of cells is controlled by growth factors that bind to receptors on the surface of the cell. The signals generated by the membrane receptors are transmitted inside the cells through signaling cascades involving kinases, G proteins, and other regulatory proteins. Ultimately, these signals affect the activity of transcription factors in the nucleus, which regulate the expression of genes crucial in cell proliferation, cell differentiation, and cell death. Oncogene products function at critical steps in these signaling path­ ways (Chap. 77). Inappropriate activation of these pathways can lead to tumorigenesis. MECHANISMS OF ONCOGENE ACTIVATION ■ ■POINT MUTATION Point mutation (alternatively known as single nucleotide substitution) is a common mechanism of oncogene activation. For example, point mutations in KRAS are present in >95% of pancreatic cancers and 40% of colon cancers. Activating KRAS mutations are less common in other cancer types, although they can occur at significant frequencies in leukemia, lung, and thyroid cancers. Remarkably—and in contrast to the diversity of mutations found in tumor-suppressor genes—most of the activated KRAS alleles contain point mutations in codons 12, 13, or 61. These mutations lead to constitutive activation of the mutant RAS protein. The restricted pattern of mutations observed in onco­ genes compared to that of tumor-suppressor genes reflects the fact that gain-of-function mutations must occur at specific sites, while a broad variety of mutations can lead to loss of activity. Indeed, inactivation of a gene can in theory be accomplished through the introduction of a stop codon anywhere in the coding sequence, whereas activations require precise substitutions at residues that can somehow lead to an increase in the activity of the encoded protein under particular circumstances within the cell. ■ ■DNA AMPLIFICATION The second mechanism for activation of oncogenes is DNA sequence amplification, leading to overexpression of the gene product. This increase in DNA copy number may cause cytologically recognizable chromosome alterations referred to as homogeneous staining regions (HSRs) if integrated within chromosomes, or double minutes (dmins) if extrachromosomal. Numerous genes have been reported to be amplified in cancer. Several of these genes, including NMYC and LMYC, were identified through their presence within the amplified DNA sequences of a tumor and their homology to known oncogenes. Because amplified regions often include hundreds of thousands of base pairs, multiple oncogenes may be amplified in a single amplicon in some cancers. For example, MDM2, GLI1, CDK4, and TPSPAN31 at chromosomal location 12q1315 have been shown to be co-amplified in several types of sarcomas and other tumors; which of these genes play the causal role in the neoplastic process is still an active area of research. Amplification of a cellular gene is often a predictor of poor prognosis; for example, ERBB2/HER2 and NMYC are often amplified in aggressive breast cancers and neuro­ blastoma, respectively. ■ ■CHROMOSOMAL REARRANGEMENT Chromosomal alterations provide important clues to the genetic changes in cancer. The chromosomal alterations in human solid tumors such as carcinomas are heterogeneous and complex and occur as a result of the frequent chromosomal instability observed in these tumors (see below). In contrast, the chromosome alterations in myeloid and lymphoid tumors are often simple translocations, that is, reciprocal transfers of chromosome arms from one chromosome to another. The breakpoints of recurring chromosome abnormalities usually occur at the site of cellular oncogenes. Table 76-2 lists representative examples of recurring chromosome alterations in malignancy and the associated gene(s) rearranged or deregulated by the chromosomal rearrangement. Translocations are often observed in liquid tumors in general and are particularly common in lymphoid tumors, probably because these cell TABLE 76-2  Representative Oncogenes at Chromosomal Translocations GENE (CHROMOSOME) TRANSLOCATION MALIGNANCY BCR-ABL (9;22)(q34;q11) Chronic myeloid leukemia BCL1 (11q13.3)–IgH (14q32) (11;14)(q13;q32) Mantle cell lymphoma BCL2 (18q21.3)–IgH (14q32) (14;18)(q32;q21) Follicular lymphoma FLI-EWSR1 (11;22)(q24;q12) Ewing’s sarcoma LCK-TCRB (1;7)(p34;q35) T-cell acute lymphocytic leukemia PAX3-FOXO1 (2;13)(q35;q14) Rhabdomyosarcoma PAX8-PPARG (2;3)(q13;p25) Thyroid IL21R-BCL6 (3;16)(q27;p11) Non-Hodgkin’s lymphoma TAL1-TCTA (1;3)(p34;p21) Acute T-cell leukemia TMPRSS2-ERG Rearrangement on Chr21q22 Prostate types have the capability to rearrange their DNA to generate antigen receptors. Indeed, antigen receptor genes are commonly involved in the translocations, implying that an imperfect regulation of receptor gene rearrangement may be involved in their pathogenesis. In addition to transcription factors and signal transduction molecules, translocation may result in the overexpression of cell cycle regulatory proteins or proteins such as cyclins and of proteins that regulate cell death. Recur­ rent translocations have more recently been identified in solid tumors such as prostate cancers. For example, fusions between TMPRSS2 and ERG, which are normally located in tandem on chromosome 21, con­ tribute to more than one-third of all prostate cancers. The first reproducible chromosome abnormality detected in human malignancy was the Philadelphia chromosome detected in CML. This cytogenetic abnormality is generated by reciprocal translocation involving the ABL oncogene on chromosome 9, encoding a tyrosine kinase, being placed in proximity to the breakpoint cluster region (BCR) gene on chromosome 22. Figure 76-3 illustrates the genera­ tion of the translocation and its protein product. The consequence of expression of the BCR-ABL gene product is the activation of signal transduction pathways leading to cell growth independent of normal external signals. Imatinib, a drug that specifically blocks the activity of Abl tyrosine kinase, has shown remarkable efficacy with little tox­ icity in patients with CML. The successful targeting of BCR-ABL by imatinib is the paradigm for molecularly targeted anticancer therapies. CHAPTER 76 CHROMOSOMAL INSTABILITY IN SOLID TUMORS Solid tumors generally contain an abnormal number of chromosomes, a state known as aneuploidy. Chromosomes from aneuploid tumors also exhibit structural alterations such as translocations, deletions, and amplifications. These abnormalities reflect an underlying defect in cancer cells known as chromosomal instability. While aneuploidy is a striking cellular phenotype, chromosomal instability is manifest as only a small increase in the tendency of cells to gain, lose, or rearrange chromosomes during any given cell cycle. This intrinsically low rate of chromosome aberration implies that cancer cells become aneuploid only after many generations of clonal expansion. The molecular basis of aneuploidy remains incompletely understood. It is widely believed that defects in checkpoints, the quality-control mechanisms that halt the cell cycle if chromosomes are damaged or misaligned, contribute to chromosomal instability. This hypothesis emerged from experimental observations that the tumor suppressor p53 controls checkpoints that regulate the initiation of DNA replication and the onset of mitosis. These processes are therefore defective in many cancer cells. The mitotic spindle checkpoint, which ensures proper chromosome attach­ ment to the mitotic spindle before allowing the sister chromatids to separate, is also altered in some cancers, irrespective of p53 status. The precise relationship between checkpoint deficiency, p53, and chromosomal instability remains unclear, but it is believed that even a subtle perturbation of the highly orchestrated process of cell divi­ sion can impact the ability of a cell to faithfully replicate and segregate its complement of chromosomes. From a therapeutic standpoint, the checkpoint defects that are prevalent in cancers have been proposed as vulnerabilities that may be exploited by novel agents and combinatorial strategies. Cancer Genetics In contrast to the genome-wide cytogenetic changes that are typical indications of an underlying chromosomal instability, more focal pat­ terns of chromosomal rearrangement have been recurrently detected in many cancer types. A curious phenomenon known as chromothripsis causes dozens of distinct breakpoints that are localized on one or sev­ eral chromosomes. These striking structural alterations are thought to reflect a single event in which a chromosome is fragmented and then imprecisely reassembled. In some cancer types, chromothripsis contributes to oncogene amplification and tumor suppressor gene inactivation in a substantial proportion of tumors. While the exact pro­ cess that underlies chromothripsis remains obscure, a transient period of extreme instability stands in contrast to the gradual loss, gain, and rearrangement of chromosomes that are typically observed in serially cultured cancer cells. Chr 9 Changed Chr 9 Chr 22 BCR BCR Chromosome translocation 9q34 ABL 22q11 FIGURE 76-3  Specific translocation seen in chronic myeloid leukemia (CML). The Philadelphia chromosome (Ph) is derived from a reciprocal translocation between chromosomes 9 and 22 with the breakpoint joining the sequences of the ABL oncogene with the BCR gene. The fusion of these DNA sequences allows the generation of an entirely novel fusion protein with modified function. PART 4 Oncology and Hematology TUMOR-SUPPRESSOR GENE INACTIVATION IN CANCER The normal role of tumor-suppressor genes is to restrain cell growth, and the function of these genes is inactivated in cancer. The three major types of somatic lesions observed in tumor-suppressor genes during tumor development are point mutations, small insertions and/or deletions known as indels, and large deletions. Point mutations or indels in the coding region of tumor-suppressor genes will frequently lead to truncated protein products or allele-specific loss of RNA expression by the process of nonsense-mediated decay. Unlike the highly recurrent point mutations that are found in critical positions of activated onco­ genes, known as mutational hotspots, the point mutations that cause tumor-suppressor gene inactivation tend to be distributed throughout the open reading frame. Large deletions lead to the loss of a functional product and sometimes encompass the entire gene or even the entire chromosome arm, leading to loss of heterozygosity (LOH) in the tumor DNA compared to the corresponding normal tissue DNA (Fig. 76-4). Mapping regions of LOH was a useful approach in the positional clon­ ing of many tumor-suppressor genes. The rate of LOH is increased in the presence of chromosomal instability, a relationship that would explain the selective forces leading to the high prevalence of aneuploidy in late-stage cancers. Gene silencing, an epigenetic change that leads to the loss of gene expression, occurs in conjunction with hypermethylation of the promoter and histone deacetylation, and is another mechanism of tumor-suppressor gene inactivation. An epigenetic modification refers to a covalent modification of chromatin, heritable by cell progeny that may involve DNA but does not involve a change in the DNA sequence. FAMILIAL CANCER SYNDROMES A small fraction of cancers occurs in patients with a genetic predispo­ sition. Based on studies of inherited and sporadic forms of retinoblas­ toma, Knudson and others formulated a hypothesis that explains the differences between sporadic and inherited forms of the same tumor type. In inherited forms of cancer, called cancer predisposition syn­ dromes, one allele of a particular tumor-suppressor gene is inherited in mutant form. This germline mutation is not sufficient to initiate a tumor, however; the other allele, inherited from the unaffected parent, must become somatically inactivated in a normal stem cell for tumori­ genesis to be initiated. In sporadic (noninherited) forms of the same disease, all cells in the body start out with two normal copies of the tumor-suppressor gene. A single cell must then sequentially acquire Ph Chr Chimeric gene ABL BCR ABL BCR-ABL fusion protein mutations in both alleles of the tumor-suppressor gene to initiate a tumor. Thus, biallelic mutations of the same tumor-suppressor gene are required for both inherited and noninherited forms of the disease; the only difference is that individuals with the inherited form have a “head start”: they already have one allele mutated, from conception, and only need one additional mutation to initiate the process (Fig. 76-4). This distinction explains why those with inherited forms of the dis­ ease develop more cancers, at an earlier age, than the general popula­ tion. It also explains why, even though every cell in an individual with a cancer predisposition syndrome has a mutant gene, only a relatively small number of tumors arise during their lifetime. The reason is that the vast majority of cells within such individuals are functionally normal because one of the two alleles of the tumor-suppressor gene is normal. Mutations are uncommon events, and only the rare cells that develop a mutation in the remaining normal allele will exhibit uncontrolled proliferation. The same principle applies to virtually all types of cancer predisposition syndromes, though the particular genes differ. For example, inherited mutations in RB1, WT1, VHL, APC, and BRCA1 lead to predispositions to retinoblastomas, Wilms’ tumors, renal cell carcinomas, colorectal carcinomas, and breast carcinomas, respectively (Table 76-3). Also note that the biallelic inactivation of any of these genes is not sufficient to develop cancer; it requires other, additional somatic alterations in other genes for the initiating cells to evolve to malignancy, as noted above. Roughly 100 familial cancer syndromes have been reported; the great majority are very rare. Most of these syndromes exhibit an autosomal dominant pattern of inheritance, although some of those associated with DNA repair abnormalities (xeroderma pigmentosum, Fanconi’s anemia, ataxia telangiectasia) are inherited in an autosomal recessive fashion. Table 76-3 shows a number of cancer predisposition syndromes and the responsible genes. Familial adenomatous polyposis (FAP) is a dominantly inherited colon cancer syndrome caused by germline mutations in the adeno­ matous polyposis coli (APC) tumor-suppressor gene on chromosome 5. Affected individuals develop hundreds to thousands of adenomas in the colon. In each of these adenomas, the APC allele inherited from the nonaffected parent has been inactivated by virtue of a somatic mutation (Fig. 76-2). This inactivation usually occurs through a gross chromosomal event resulting in loss of all or a large part of the long arm of chromosome 5, where APC resides. In other cases, the remain­ ing allele is inactivated by a subtle intragenic mutation of APC, which is typically a single base substitution resulting in a nonsense codon. A1 + + B1 A2 A1 + Rb B2 Markers A and B B2 Tumor formation A1 + Rb B1 A3 B3 A1 Rb Rb B1 FIGURE 76-4  Diagram of possible mechanisms for tumor formation in an individual with hereditary (familial) retinoblastoma. On the left is shown the pedigree of an affected individual who has inherited the abnormal (Rb) allele from her affected mother. The normal allele is shown as a (+). The four chromosomes of her two parents are drawn to indicate their origin. Flanking the retinoblastoma locus are genetic markers (A and B) also analyzed in this family. Markers A3 and B3 are on the chromosome carrying the retinoblastoma disease gene. Tumor formation results when the normal allele, which this patient inherited from her father, is inactivated. On the right are shown four possible ways in which this could occur. In each case, the resulting chromosome 13 arrangement is shown. Note that in the first three situations, the normal allele (B1) has been lost in the tumor tissue, which is referred to as loss of heterozygosity (LOH) at this locus. Gross chromosomal losses occur more commonly than point muta­ tions in normal cells, explaining why chromosomal loss rather than point mutation is the predominant mechanism underlying the inacti­ vation of the normal allele of APC. The same is true for other cancer predisposition syndromes caused by other inherited tumor suppressor gene mutations; gross chromosomal events are generally responsible for inactivation of the tumor-suppressor gene allele inherited from the nonaffected parent. Several thousand adenomas form in FAP patients, and a small subset of the millions of cells within an adenoma will acquire a second mutation, leading to tumor progression, that is, a larger adenoma. A third mutation in such a larger adenoma may convert it to a carcinoma. If untreated (by colectomy), at least one of the adenomas will progress to cancer by the time patients are in their mid-40s. APC is a gatekeeper for colon tumorigenesis in the sense that in the absence of mutation in APC (or a gene acting within the same pathway), a colorectal tumor simply cannot be initiated. Figure 76-5 shows the germline and somatic mutations found in the APC gene. A negative regulator of a signaling pathway that determines cell fate during development, the APC protein provides differentiation and apoptotic cues to colonic epithelial cells as they migrate up the crypt. Defects in this process can lead to abnormal accumulation of cells that would otherwise differentiate and eventually undergo apoptosis. In contrast to patients with FAP, patients with hereditary nonpol­ yposis colon cancer (HNPCC, or Lynch syndrome) do not develop polyposis, but instead develop only one or a small number of adenomas that rapidly progress to cancer. HNPCC is due to inherited mutations in one of four DNA mismatch repair genes (Table 76-3) that are com­ ponents of a repair system responsible for correcting errors in newly replicated DNA. Germline mutations in MSH2 and MLH1 together account for more than 90% of HNPCC cases, and mutations in MSH6 and PMS2 account for the remainder. When a somatic mutation inac­ tivates the remaining wild-type allele of a mismatch repair gene, the Chromosome arrangement in the tumor Loss of normal chr 13 Rb A3 B3 Loss and reduplication A3 A3 Rb Rb B3 A3 B3 B3 Mitotic crossing over A1 Rb Rb B3 A3 B3 CHAPTER 76 Independent mutation or small deletion A3 Cancer Genetics B3 cell develops a hypermutable phenotype characterized by profound genomic instability that is most readily apparent in short repeated sequences called microsatellites and is sometimes called microsatellite instability (MSI). The high rate of mutation in such cells impacts all genes, including oncogenes and tumor-suppressor genes, and thereby accelerates the activation of the former and the inactivation of the latter (Fig. 76-2). HNPCC can be considered a disease of tumor progression; once tumors are initiated (by an inactivating mutation of APC or by some other gene in the APC pathway), tumors rapidly progress because of the accelerated mutation rate. Progression from a tiny adenoma to carcinoma takes only a few years in HNPCC patients instead of the two or three decades this progression takes in patients with FAP (or in patients with sporadic colorectal tumors). Approximately half of HNPCC patients develop colorectal cancers by the time they are in their mid-40s—similar to that of FAP patients. This coincidence in age of onset emphasizes that both tumor initiation (abnormal in FAP patients) and tumor progression (abnormal in HNPCC patients) are the two pillars of cancer development and are equally important for cancer development. Another general principle is apparent from the comparison between FAP and HNPCC patients. The tumors in FAP patients, like those in patients without hereditary predisposition to cancers, exhibit chro­ mosomal instability rather than MSI. Indeed, MSI and chromosomal instability tend to be mutually exclusive in colon cancers, suggest­ ing that they represent alternative mechanisms for the generation of genomic instability (Fig. 76-2). Other cancer types rarely exhibit MSI. Chromosomal instability is far more prevalent than MSI among all cancer types, perhaps explaining why nearly all cancers are aneuploid. Although most autosomal dominant inherited cancer syndromes are due to mutations in tumor-suppressor genes (Table 76-3), there are a few interesting exceptions. Multiple endocrine neoplasia type 2, a dominant disorder characterized by pituitary adenomas, medullary TABLE 76-3  Cancer Predisposition Syndromes and Associated Genes SYNDROME GENE CHROMOSOME INHERITANCE TUMORS Ataxia telangiectasia ATM 11q22-q23 AR Breast Autoimmune lymphoproliferative syndrome FAS FASL Birt-Hogg-Dubé syndrome FLCN 17p11.2 AD Kidney (hybrid oncocytic, chromophobe) Bloom syndrome BLM 15q26.1 AR Various Cowden syndrome PTEN 10q23 AD Breast, thyroid Familial adenomatous polyposis APC MUTYH Familial melanoma CDKN2A 9p21 AD Melanoma, pancreatic Familial Wilms’ tumor WT1 11p13 AD Kidney (pediatric) Hereditary breast/ovarian cancer BRCA1 BRCA2 Hereditary diffuse gastric cancer CDH1 16q22 AD Stomach Hereditary multiple exostoses EXT1 EXT2 Hereditary retinoblastoma RB1 13q14.2 AD Retinoblastoma, osteosarcoma Hereditary nonpolyposis colon cancer (HNPCC) MSH2 MLH1 MSH6 PMS2 PART 4 Oncology and Hematology Hereditary papillary renal carcinoma MET 7q31 AD Papillary kidney Juvenile polyposis syndrome SMAD4 BMPR1A Li-Fraumeni syndrome TP53 17p13.1 AD Sarcoma, breast Multiple endocrine neoplasia type 1 MEN1 11q13 AD Parathyroid, endocrine, pancreas, and pituitary Multiple endocrine neoplasia type 2a RET 10q11.2 AD Medullary thyroid carcinoma, pheochromocytoma Neurofibromatosis type 1 NF1 17q11.2 AD Neurofibroma, neurofibrosarcoma, brain Neurofibromatosis type 2 NF2 22q12.2 AD Vestibular schwannoma, meningioma, spine Nevoid basal cell carcinoma syndrome (Gorlin’s syndrome) PTCH1 9q22.3 AD Basal cell carcinoma, medulloblastoma, jaw cysts Peutz-Jeghers syndrome STK11/LKB1 19p13.3 AD Gastrointestinal, breast Tuberous sclerosis TSC1 TSC2 von Hippel–Lindau disease VHL 3p25-26 AD Kidney, cerebellum, pheochromocytoma Abbreviations: AD, autosomal dominant; AR, autosomal recessive. Number of mutations Number of mutations Somatic O ARM 15 aa 20 aa Basic E/D APC Germline 1000 1200 1400 FIGURE 76-5  Germline and somatic mutations in the tumor-suppressor gene adenomatous polyposis coli (APC). APC encodes a 2843-amino-acid protein with six major domains: an oligomerization region (O), armadillo repeats (ARM), 15-amino-acid repeats (15 aa), 20-amino-acid repeats (20 aa), a basic region, and a domain involved in binding EB1 and the Drosophila discs large homologue (E/D). Shown are 650 somatic and 826 germline mutations representative of the mutations that occur within the APC gene (from the APC database at www.umd.be/APC). All known pathogenic mutations of APC result in the truncation of the APC protein. Germline mutations are found to be relatively evenly distributed up to codon 1600 except for two mutation hotspots surrounding amino acids 1061 and 1309, which together account for one-third of the mutations found in familial adenomatous polyposis (FAP) families. 10q24 1q23 AD Lymphomas 5q21 1p34.1 AD AR Colorectal (early onset) 17q21 13q12.3 AD Breast, ovarian, prostate 8q24 11p11-12 AD Exostoses, chondrosarcoma 2p16 3p21.3 2p16 7p22 AD Colon, endometrial, ovarian, stomach, small bowel, ureter carcinoma 18q21 AD Gastrointestinal, pancreatic 9q34 16p13.3 AD Angiofibroma, renal angiomyolipoma MCR 1600 1800 2000 2200 2400 2600 2800 Amino acid number carcinoma of the thyroid, and (in some pedigrees) pheochromocy­ toma, is due to gain-of-function mutations in the proto-oncogene RET on chromosome 10. Similarly, gain-of-function mutations in the tyrosine kinase domain of the MET oncogene lead to hereditary papil­ lary renal carcinoma. Interestingly, loss-of-function mutations in the RET gene cause a completely different disease, Hirschsprung’s disease (aganglionic megacolon [Chaps. 339 and 400]). Although the heritable forms of cancer have taught us much about the mechanisms of growth control, most forms of cancer do not follow simple Mendelian patterns of inheritance. The majority of human can­ cers arise in a sporadic fashion, solely as a result of somatic mutation, and in the absence of any mutations in cancer-predisposing genes in their germlines. GENETIC TESTING FOR FAMILIAL CANCER The discovery of cancer susceptibility genes raises the possibility of DNA testing to predict the risk of cancer in individuals of affected families. An algorithm for cancer risk assessment and decision making in high-risk families using genetic testing is shown in Fig. 76-6. Once a mutation is discovered in a family, subsequent testing of asymptomatic family members is crucial. A negative gene test in these individuals can prevent years of anxiety, providing comfort in the knowledge that their cancer risk is no higher than that of the general population. On the other hand, a positive test may lead to alteration of clinical man­ agement, such as increased frequency of cancer screening and, when feasible and appropriate, prophylactic surgery. Potential negative con­ sequences of a positive test result include psychological distress (anxi­ ety, depression) and discrimination, although the Genetic Information Patients (1) from family with a known cancer syndrome, (2) from a family with a history of cancer, (3) with early onset cancer Pretest counseling Review of family history to confirm/identify possible cancer syndromes and candidate genes Informed consent Testing of cancer patient Negative test: no disease-causing mutations identified Identification of disease-causing mutation Screening of asymptomatic family members Negative test: family member has no increased risk of cancer FIGURE 76-6  Algorithm for genetic testing in a family with cancer predisposition. The key step is the identification of a disease mutation in a cancer patient, which is an indication for the testing of asymptomatic family members. Asymptomatic family members who test positive may require increased screening or surgery, whereas those who test negative are at no greater risk for cancer than the general population. It should be emphasized that no molecular assay used for this sort of testing is 100% sensitive; negative results must be interpreted with this caveat in mind. Nondiscrimination Act (GINA) makes it illegal for predictive genetic information to be used to discriminate in health insurance or employ­ ment. Testing should therefore not be conducted without counseling before testing is administered and during and after disclosure of the test result. It is now feasible to obtain high-quality sequence of all of the proteincoding DNA sequences, and even of the entire genome, in any given individual. In such studies, numerous variants in DNA sequences will inevitably be identified in every subject, but the significance of the vast majority of these DNA sequence findings will be unclear. Even muta­ tions in tumor-suppressor genes can be difficult to interpret unless there is an obvious functional implication, such as the truncation of the open reading frame, or that particular mutation has previously been correlated with cancer in other individuals. Germline mutations associated with cancer predisposition are uncommon in individuals without a family history of cancer, though they do occur. Much more common are variants of unknown significance (VUS). VUS that are found during genetic testing cannot be used to evaluate the relative risk of cancer but may nonetheless cause anxiety because they represent a deviation from the reference allele that is established as “normal.” Because of the low yield of informative mutations that modify cancer risk and the frequent identification of VUS, it is generally not appropri­ ate to use DNA sequencing to assess cancer risk in individuals without a family history of cancer. However, there are exceptions. Testing may be appropriate in some subpopulations with a known increased risk, even without a personal family history. For example, two mutations in the breast cancer susceptibility gene BRCA1, 185delAG and 5382insC, exhibit a sufficiently high frequency in the Ashkenazi Jewish popula­ tion that genetic testing based on ethnicity alone may be warranted. CHAPTER 76 Cancer Genetics It is important that genetic test results be communicated to families by trained genetic counselors. To ensure that the families clearly under­ stand its advantages and disadvantages and the impact it may have on disease management and psyche, genetic testing should never be done before counseling. Significant expertise is needed to communicate the results of genetic testing to families. VIRUSES IN HUMAN CANCER Several human malignancies are associated with viruses. Examples include Burkitt’s lymphoma (Epstein-Barr virus; Chap. 199), hepato­ cellular carcinoma (hepatitis viruses), cervical cancer (human papil­ lomavirus [HPV]; Chap. 203), and T-cell leukemia (retroviruses; Chap. 207). There are several types of HPV, including the high-risk types 16 and 18 that are strongly associated with the development of cervical, vulvar, vaginal, penile, anal, and oropharyngeal cancer. The mechanisms of action of all these viruses involve inactivation of tumorsuppressor genes. For example, HPV proteins E6 and E7 bind to and inactivate cellular tumor suppressors p53 and pRB, respectively. This is the reason that HPV is such a potent initiator of cancer: infection with a virus is tantamount to having two of the three mutant driver genes required for cancer, that is, one viral oncogene inactivates p53 and the other inactivates Rb. Once these two inactivated gene products initiate tumorigenesis, only one additional mutant gene is required for these tumors to progress to malignancy. ■ ■CANCER GENOMES The advent of relatively inexpensive technologies for rapid and high-throughput DNA sequencing has facilitated the comprehensive analysis of numerous genomes from many types of tumors. This unprecedented view into the genetic nature of cancer has provided remarkable insights. Most cancers do not arise in the context of a mutator phenotype, and accordingly, the number of mutations in even the most advanced cancers is relatively modest. Common solid tumors harbor 30–70 subtle mutations that are nonsynonymous (i.e., result in an amino acid change in the encoded protein). Liquid tumors such as leukemias, as well as pediatric tumors, typically have fewer than 20 mutations. The vast majority of the mutations detected in tumors are not functionally significant; they simply arose by chance in a single cell that gave rise to an expanding clone. Such mutations, which pro­ vide no selective advantage to the cell in which they occur, are known as passenger mutations. As noted above, only a small number of the mutations confer a selective growth advantage and thereby promote tumorigenesis. These functional mutations are known as driver muta­ tions, and the genes in which they occur are called driver genes. The frequency and distribution of driver mutations within a single tumor type can be represented as a topographical landscape. The picture that emerges from cancer genome studies reveals that most genes that are mutated in tumors are actually mutated at relatively low frequencies, as would be expected of passenger genes, whereas a small number of genes (the driver genes) are mutated in a large proportion of tumors. Only ~200 driver genes contribute to the development of solid tumors of all kinds. Driver genes that play a role in ever smaller fractions of cancers are still being discovered. The majority of the muta­ tions in driver genes provide a direct selective growth advantage by altering the signaling pathways that mediate cell survival or the deter­ mination of cell fate. The remaining driver gene mutations indirectly provide a selective growth advantage by accelerating the mutation rate of proto-oncogenes and tumor-suppressor genes. That the same driver genes play a role in multiple cancer types was unexpected before their discovery and has important implications for the development of new “tumor-agnostic” therapeutic and diagnostic approaches. Moreover, the functions of all these driver genes can be organized into a small number of signaling pathways, as shown in Table 76-4. As a consequence of the mutations they harbor, cancer cells invari­ ably express mutant proteins that are only rarely found in normal cells. Some of these mutant proteins are processed and displayed on the cell surface in the context of major histocompatibility complexes, a process that would normally facilitate their recognition by the adaptive immune system. Thus, all cancers have the theoretical potential to be recognized as foreign, or “nonself,” via the display of these tumor-spe­ cific antigens, known as mutation-associated neoantigens (MANAs). In fact, established tumors invariably prevent the activation of local T cells by inducing an intercellular suppressive mechanism known as an immune checkpoint. Therapeutic approaches to exploit this potential vulnerability by blocking immune checkpoints have elicited striking responses in patients with several types of cancer. PART 4 Oncology and Hematology It was hypothesized that the potential immunogenicity of a tumor would be related to the total number of distinctive neoantigens it can express, which in turn is directly determined by the total number of mutations in the cancer genome. This does seem to be the case. Colorectal cancers that develop as a result of mismatch repair defi­ ciency and smoking-related lung cancers, both of which characteristi­ cally harbor large numbers of mutations, exhibit more robust responses to therapeutic immune checkpoint blockade than most other tumor types. Notably, driver mutations as well as passenger mutations that result in the expression of mutant proteins can both contribute to the display of immunogenic neoantigens. Thus, the total number of coding TABLE 76-4  Signaling Pathways Altered in Cancer REPRESENTATIVE DRIVER GENES PROCESS PATHWAY Cell survival Cell cycle regulation/ apoptosis RB1, BCL2   RAS KRAS, BRAF   PIK3CA PTEN, PIK3CA   JAK/STAT JAK2, FLT3   MAPK MAP3K, ERK   TGF-β BMPR1A, SMAD4 Cell fate Notch NOTCH1, FBWX7   Hedgehog PTCH1, SMO   WNT/APC APC, CTNNB1   Chromatin modification DNMT1, IDH1   Transcriptional regulation AR, KLF4 Genome maintenance DNA damage signaling and repair ATM, BRCA1 mutations, a metric known as mutational load, is one of the determi­ nants of potential immunogenicity. The ability of cancer cells to evade immune-mediated cell death is an intrinsic property that is essential for their continued growth. While tumor suppressor genes and oncogenes have been intensively studied with respect to their effects on the intracellular signaling pathways that regulate cell proliferation and cell death, little is known about how these genetic alterations affect the interactions between cancer cells and neighboring immune cells. In particular, neoplastic cells contain­ ing certain mutations may be culled by the immune system because the mutations create neoantigens that can be recognized by T cells. ■ ■TUMOR HETEROGENEITY The mutant cells that compose a single tumor are not genetically identical. Rather, cells obtained from different sites on a tumor will harbor common mutations as well as mutations that are unique to each sample. Genetic heterogeneity results from the ongoing acquisition of mutations during tumor growth. Each time a genome is replicated, there is a small but quantifiable probability that a mutation will spon­ taneously arise as a result of a replication error and be passed on to the cellular progeny. This is true in normal cells or in tumor cells. Any ran­ domly chosen cell from the skin of one individual will harbor hundreds of genetic alterations that distinguish it from a different randomly chosen skin cell, and the same is true for all organs of self-renewing tissues. Tumors are actually less genetically heterogeneous than normal tissues; any two randomly chosen cells from a tumor of an individual will have fewer differences than any two randomly chosen cells from that individual’s normal tissues. The reason for this decrease in hetero­ geneity is clonal expansion, the fundamental feature of tumorigenesis. Every time a clonal expansion occurs, a genetic bottleneck wipes out heterogeneity among the cells that did not expand; these unexpanded cells either die or form only a minute proportion of the total cells in the expanding tumor. The mutations that vary between cells of a given tumor are invari­ ably passenger mutations that arose since the last evolutionary bottle­ neck, that is, those mutations that arose during the expansion of the founder cell that gave rise to the final clonal expansion. In contrast, the passenger mutations that were present in the founder cell will be uniformly present in every cell in the tumor. In that respect, these pas­ senger mutations are not heterogeneously distributed and are in fact uniformly present in virtually all cancer cells. These “clonal” mutations, i.e., present in all cells of the cancers, are the main source of MANAs that can be exploited through immune checkpoint inhibitors. The total number of mutations and their distribution within tumor cells repre­ sent a complex interplay between the age of the patient (the older the patient, the more passenger mutations will have accumulated in the founding cell of the first clonal expansion) and the evolutionary history of the cancer (its age and number of clonal expansions it experienced). Tumor heterogeneity has been recognized for decades at the cyto­ genetic, biochemical, and histopathologic levels. However, it is only recently, with the advent of a deep understanding of cancer genetics, that genetic heterogeneity can be interpreted in a medically relevant fashion. The first important point to recognize about tumor hetero­ geneity is that it is only the variation in driver gene alterations that is important; the cellular distribution of passenger gene mutations is irrelevant except for immune-related phenomena. In this discussion of heterogeneity, we can expand the definition of “driver genes” to include those that provide a selective growth advantage in the face of therapy in addition to those that provide a selective growth advantage during tumor evolution, prior to treatment. Type I heterogeneity refers to that among tumors of the same type from different patients (Fig. 76-7). Though adenocarcinomas of the lung generally harbor mutations in three or more driver genes, the genes dif­ fer among the patients, and the precise mutations within the same gene can vary considerably. Type I heterogeneity is the basis for precision medicine, where the goal is to treat patients with drugs that target the proteins encoded by genetic alterations within their specific tumors. Type II heterogeneity refers to the genetic heterogeneity among differ­ ent cells from the same primary tumor. Tumors continue to evolve as Intratumoral heterogeneity within a primary tumor Intermetastatic heterogeneity between two metastases A Clone 1 Clone 2 Liver Founder cells Founder cells Clone 4 Clone 3 Intrametastatic heterogeneity within metastatic lesions Interpatient heterogeneity D C FIGURE 76-7  Four types of tumor heterogeneity. Tumor heterogeneity is the inevitable result of cell proliferation, as new mutations are introduced during clonal expansion. In a typical tumor (upper left), founder cells that harbor a large fraction of the total mutations give rise to subclones, which continue to evolve independently. The tumors of the founding populations are shown in the middle of each circle; the distinct subclones are shown around the periphery. A. Heterogeneity among the cells of a primary tumor is known as intratumoral heterogeneity. B. Heterogeneity among the founding cells of distinct metastatic lesions (marked as 1 and 2) that arise in the same patient is known as intermetastatic heterogeneity. C. Heterogeneity among the cells of each metastatic tumor is known as intrametastatic heterogeneity. D. Interpatient heterogeneity. The mutations in the tumors of two patients are almost completely distinct. (Reproduced with permission from B Vogelstein et al: Cancer genome landscapes. Science 339(6127):1546, 2013.) they grow, and different cells of the same cancer, in its original site (e.g., the pancreas), may acquire other driver gene mutations that are not shared among the other cells of the tumor. Such a mutation can result in a small clonal expansion that may or may not be important biologi­ cally. In cases in which the primary tumor can be surgically excised, such mutations are unimportant unless they give rise to type III heterogeneity (described below). The reason they are unimportant is because all primary tumor cells, whether homogeneous or not, are removed by the surgical procedure. In primary tumors that cannot be completely excised (such as most advanced brain tumors and many pancreatic ductal adenocarcinomas), heterogeneity is biomedically important because it can give rise to drug resistance, analogously to that described for type IV heterogeneity (see below). Type III hetero­ geneity refers to the genetic differences among the founder cells of the metastatic lesions from the same patient. For example, a patient with melanoma may have 100 different metastases distributed throughout various organs. Only if a mutant BRAF is present in every founder cell of every metastasis, then the patient has a chance at a complete response to a BRAF inhibitor. There have been several recent detailed studies of the metastases from various tumor types. Fortunately, these studies suggest there is very little, if any, type III heterogeneity among driver genes, a necessary prerequisite for the successful implementa­ tion of current and future targeted therapies. Finally, type IV hetero­ geneity refers to that among cells of individual metastatic lesions. As the founder cell of each metastasis expands to become detectable, it acquires mutations, a small number of which can act as “drivers” when the patient is exposed to therapeutics. This type of heterogeneity is of major clinical importance, as it has been shown to be responsible for the development of resistance in virtually all targeted therapies. The development of such resistance is a fait accompli based simply on known mutation rates and genetic resistance mechanisms. The only way to circumvent acquired resistance is to treat metastatic tumors earlier (i.e., in adjuvant setting, before much tumor expansion has occurred) or to treat with combinations of drugs for which crossresistance is genetically impossible. B Metastasis 1 Pancreas Metastasis 2 Primary tumor Patient 1 Patient 2 CHAPTER 76 Cancer Genetics PERSONALIZED CANCER DETECTION AND TREATMENT High-throughput DNA sequencing has led to an unprecedented under­ standing of cancer at the molecular level. A comprehensive mutation profile provides a molecular history of a given tumor and insights into how it arose. Because tumor cells and tumor DNA are shed into the blood and other bodily fluids, common driver mutations can be used as highly specific biomarkers for early detection. For diagnosed tumors, tumor-specific mutations can be used to estimate tumor burden, assess treatment responses, and detect recurrence. In some cases, information regarding specific genes and pathways that are altered provides patients and physicians with options for personalized therapy. This general approach is sometimes referred to as precision medicine. Because tumor behavior is highly variable, even within a tumor type, personalized information-based medicine can supplement and perhaps eventually supplant histology-based tumor assessment, especially in the case of tumors that are resistant to con­ ventional therapeutic approaches. Conversely, molecular nosology has revealed similarities in tumors of diverse histotype. The success of the precision medicine approach in any given patient depends on the pres­ ence of tumor-associated genetic alterations that are actionable (i.e., can be targeted with a specific drug). Examples of currently actionable changes include mutations in BRAF (targeted by the drug vemu­ rafenib), RET (targeted by sunitinib and sorafenib), ALK rearrange­ ments (targeted by crizotinib), and mismatch repair genes (targetable by immune checkpoint inhibitors). The development of new targeted agents is at present hindered by the fact that most such agents can only target activated oncogenes, while the great majority of genetic alterations in common solid tumors are those that inactivate tumor-suppressor genes. Because all drugs, whether for use in oncology or any other purpose, can only inhibit protein actions, drugs cannot be used to directly target the proteins encoded by inactivated tumor-suppressor genes; these proteins are already inactive. More information about the pathways through which tumor-suppressor genes act may provide a way around this # 06 - 77 Cancer Cell Biology ### 77 Cancer Cell Biology obstacle. For example, when a tumor-suppressor gene is inactivated, some downstream component of the pathway is likely to be activated, thereby presenting a realistic target. Alternatively, the mutational inac­ tivation of a DNA repair pathway might create a unique dependence on the repair pathways that remain intact. An example of this is pro­ vided by PARP-1 inhibitors, which have been successfully used to treat patients whose tumors have inactivating mutations of genes involved in DNA repair processes, such as BRCA1. Patterns of global gene expres­ sion can be used to help unravel such pathways and are already being used to predict drug sensitivities and provide prognostic information in addition to that provided by DNA sequence analysis. Evaluation of proteomic and metabolomic patterns may also prove useful for this purpose. ■ ■THE FUTURE A revolution in cancer genetics has occurred in the past 30 years. Most types of cancer are now understood at the DNA sequence level, and this accomplishment has led to an increasingly refined understanding of tumorigenesis. Cancer gene mutations have proven to be reliable biomarkers for cancer detection and monitoring as well as for inform­ ing therapeutics through precision medicine approaches. Gene-based tests are already standard of care for patients with certain tumor types, such as colorectal and lung cancers, and the utility of these tests will undoubtedly be expanded in the coming years as new therapies and ways of predicting responses to therapies are developed. While effec­ tive treatment of advanced cancers remains difficult, the early promise shown by immune-based therapies notwithstanding, it is expected that breakthroughs in these areas will continue to emerge and be applicable to an ever-increasing number of cancers. Moreover, with the hoped-for advances in diagnostics, particularly in the earlier detection of cancers, the new and old therapies for cancer can be expected to have a much greater impact on reducing cancer deaths. PART 4 Oncology and Hematology Acknowledgments The authors gratefully acknowledge the past contributions of Pat J. Morin, Jeff Trent, and Francis Collins to earlier versions of this chapter. ■ ■FURTHER READING Bunz F: Principles of Cancer Genetics, 3rd ed. Dordrecht, Springer, 2022. Le DT et al: PD-1 Blockade in tumors with mismatch-repair deficiency. N Engl J Med 372:2509, 2015. Vogelstein B, Kinzler KW: The path to cancer—three strikes and you’re out. N Engl J Med 373:1895, 2015. Vogelstein B et al: Cancer genome landscapes. Science 339:1546, 2013. Jeffrey W. Clark, Dan L. Longo Cancer Cell Biology ■ ■CANCER CELL BIOLOGY Cancers are characterized by unregulated cell division, avoidance of cell death, tissue invasion, and the ability to spread to other areas of the body (metastasize). A neoplasm is benign when it grows in an unregu­ lated fashion without tissue invasion or metastasizing. The presence of unregulated growth, tissue invasion, and the ability to metastasize is characteristic of malignant neoplasms. Cancers are named based on their tissue of origin: those derived from epithelial tissue are called car­ cinomas, those derived from mesenchymal tissues are sarcomas, and those derived from hematopoietic tissue are leukemias, lymphomas, and plasma cell dyscrasias (including multiple myeloma). Cancers arise as a consequence of genetic alterations, the vast majority of which begin in a single cell and therefore are monoclonal in origin. However, because a wide variety of genetic and epigenetic changes can occur in different cells within malignant tumors over time, as well as varied responses with their microenvironments and the biology of the patient, most cancers are characterized by plasticity and marked heterogeneity in the populations of cells and their composite behavior. In addition, extrinsic factors in the cancer environment (e.g., the stroma, infiltrating cells, various cell-to-cell interactions, spatial orientation, secreted factors, and availability of oxygen and nutrients) vary in different areas within the tumor or different metastases, com­ pounding this heterogeneity. This heterogeneity significantly compli­ cates the treatment of most cancers because it is likely that there are subsets of cells that will be resistant to therapy for a variety of reasons and will therefore survive and proliferate even if the majority of cells are killed. A few cancers appear to, at least initially, be primarily driven by an alteration in a dominant gene that produces uncontrolled cell prolif­ eration. Examples include chronic myeloid leukemia (abl), about half of melanomas (braf), Burkitt’s lymphoma (c-myc), and subsets of lung adenocarcinomas (egfr, alk, ros1, met, ret, braf, and ntrk). Genes that can promote cell growth when altered are often called oncogenes. They were first identified as critical elements of viruses that cause animal tumors; it was subsequently found that the viral genes had normal counterparts with important functions in the cell and had been cap­ tured and mutated by viruses as they passed from host to host. However, most human cancers are characterized by a multiple-step process involving many genetic abnormalities, each of which contrib­ utes to the loss of control of cell proliferation and differentiation and the acquisition of capabilities, such as tissue invasion, the ability to metastasize, angiogenesis (development of new blood vessels required for tumor growth), and alteration of the extracellular environment. These properties are not found in the normal adult cell from which the tumor is derived. Indeed, normal cells have a large number of safeguards against DNA damage (including multiple DNA repair and extensive DNA damage response mechanisms), uncontrolled prolif­ eration, and invasion. Many cancers go through recognizable steps of progressively more abnormal phenotypes: hyperplasia, to adenoma, to dysplasia, to carcinoma in situ, to invasive cancer with the ability to metastasize (Table 77-1). For most cancers, these changes occur over a prolonged period of time, usually many years. In most organs, only primitive undifferentiated cells are capable of proliferating and cells lose the capacity to proliferate as they differenti­ ate and acquire functional capabilities. The expansion of the primitive cells (stem cells) is linked to some functional need in the host, such as normal turnover of tissues or regeneration after acute injury, through receptors that receive signals from cells and other factors in the local tissue microenvironment or through hormonal and other influences delivered by the vascular supply. In the absence of such signals, the cells are at rest or quiescent (out of the cell cycle but capable of being activated to reenter the cell cycle). The signals that induce quiescence in primitive cells as well as those that keep the cells at rest are com­ plex, including the process for quiescent entry, maintenance, and exit. Although much has been learned, including the importance of notch signaling, the STING pathway, other quiescent factors, and transcrip­ tional, posttranscriptional, and epigenetic regulation in quiescent entry and maintenance, overall control of the process within the body remains incompletely understood. These signals must be, at least in part, environmental, based on the observations that a regenerating liver stops growing when it has replaced the portion that has been surgically removed after partial hepatectomy and regenerating bone marrow stops growing when the peripheral blood counts return to normal. Cancer cells clearly have lost responsiveness to such controls and do not recognize when they have overgrown the niche normally occupied by the organ from which they are derived. A better understanding of these mechanisms of growth regulation in the context of organ homeo­ stasis continues to evolve. TABLE 77-1  Phenotypic Characteristics of Malignant Cells Deregulated cell proliferation: Loss of function of negative growth regulators (tumor suppressor genes, i.e., Rb, p53) and increased action of positive growth regulators (oncogenes, i.e., Ras, Myc). Leads to aberrant cell cycle control and includes loss of normal checkpoint responses. Failure to differentiate: Arrest at a stage before terminal differentiation. May retain stem cell properties. (Frequently observed in leukemias due to transcriptional repression of developmental programs by the gene products of chromosomal translocations.) Loss of normal apoptosis pathways: Inactivation of p53, increases in Bcl-2 (antiapoptotic) family members. This defect enhances the survival of cells with oncogenic mutations and genetic instability and allows clonal expansion and diversification within the tumor without activation of physiologic cell death pathways. Genetic instability: Defects in DNA repair pathways leading to either single nucleotide or oligonucleotide mutations (as in microsatellite instability, MIN) or, more commonly, chromosomal instability (CIN) leading to aneuploidy (abnormal number of chromosomes in a cell). Caused by loss of function of a number of proteins including p53, BRCA1/2, mismatch repair genes, DNA repair enzymes, and the spindle checkpoint. Leads to accumulation of a variety of mutations in different cells within the tumor and heterogeneity. Loss of replicative senescence: Normal cells stop dividing in vitro after 25–50 population doublings. Arrest is mediated by the Rb, p16INK4a, and p53 pathways. While most cells remain arrested, genetic and epigenetic changes in a subset of cells allow further replication, leading to telomere loss, with crisis leading to death of many cells. Cells that survive often harbor gross chromosomal abnormalities and the ability to continue to proliferate. These cells express telomerase, which maintains telomeres and is important for ongoing growth of these cells. Relevance to human in vivo cancer remains uncertain. Many human cancers express telomerase. Nonresponsiveness to external growth-inhibiting signals: Cancer cells have lost responsiveness to signals normally present to stop proliferating when they have overgrown the niche normally occupied by the organ from which they are derived. Our understanding about this mechanism of growth regulation remains limited. Increased angiogenesis: Due to increased gene expression of proangiogenic factors (VEGF, FGF, IL-8, angiopoietin) by tumor or stromal cells, or loss of negative regulators (endostatin, tumstatin, thrombospondin). Invasion: Cell mobility and ability to move through extracellular matrix and into other tissues or organs. Loss of cell-cell contacts (gap junctions, cadherins) and increased production of matrix metalloproteinases (MMPs). Can take the form of epithelial-to-mesenchymal transition (EMT), with anchored epithelial cells becoming more like motile fibroblasts. Metastasis: Spread of tumor cells to lymph nodes or distant tissue sites. Limited by the ability of tumor cells to migrate out of initial site and to survive in a foreign environment, including evading the immune system (see below). Evasion of the immune system: Downregulation of MHC class I and II molecules; induction of T-cell tolerance; inhibition of normal dendritic cell and/or T-cell function; antigenic loss variants and clonal heterogeneity; increase in regulatory T cells. Shift in cell metabolism: Complex changes including alterations due to tumor stress such as hypoxia and energy generation shifts from oxidative phosphorylation to aerobic glycolysis generate building blocks for malignant cell production and proliferation. Complex interactions with the extracellular environment around the cancer cells: Induction of changes as well as complex interactions with the extracellular environment around cancer cells, including modifications to the extracellular matrix, vasculature, chemokines, mesenchymal stromal cells, fibroblasts, immune cells, other hematopoietic cells, platelets, nerves, and potentially infectious agents impacting many of the above processes. Abbreviations: FGF, fibroblast growth factor; IL, interleukin; MHC, major histocompatibility complex; VEGF, vascular endothelial growth factor. ■ ■DIFFERENCES BETWEEN PEDIATRIC AND ADULT CANCERS The underlying importance of genetic mutations and other molecular changes is similar for pediatric and adult cancers. However, some important differences exist. Childhood cancers have a different epi­ demiology (e.g., they do not have the same extent of environmental or lifestyle risk factors), are much less frequent, and have a different spectrum of frequency beginning primarily during embryogenesis in mesodermal (e.g., sarcomas or hematologic malignancies such as acute lymphocytic leukemia [ALL] or lymphomas) or ectodermal (e.g., neuronal including brain and spinal) tissues. They generally have fewer genetic changes and lower mutational burdens than adult cancers. Likely due to a number of factors including the nature of the cancers (e.g., less genetic complexity than adult cancers) and the ability of children to tolerate more intense chemotherapy regimens, childhood cancers generally tend to be much more responsive to chemotherapy than adult cancers with significantly higher rates of cure. ■ ■CANCER AS AN ORGAN THAT IGNORES ITS NICHE The fundamental cellular defects that create a malignant neoplasm act at the cellular level, and some of these are cell autonomous. However, that is not the entire story. Cancers consist of both malignant cells as well as other cells, blood vessels, extracellular matrix, and signaling and other molecules in the cancer microenvironment. They behave as organs that have lost their specialized function and stopped respond­ ing to signals that would limit their growth in tightly regulated normal tissue homeostasis. Most human cancers usually become clinically detectable when a primary mass is approximately 1 cm in diameter— such a mass consists of about 109 cells. Often, patients present with tumors that are approximately 1010 cells. Although it varies by type of cancer and where the primary tumor and metastases are located, a lethal tumor burden is usually about 1012–1013 cells. If all malignant cells were dividing without any cell death at the time of diagnosis, most patients would reach a lethal tumor burden in a very short time. How­ ever, human tumors grow by Gompertzian kinetics—this means that not every daughter cell produced by a cell division is actively dividing. In addition, the overall growth rate of a tumor depends on differences between growth rates of different cells within the tumor and rate of cell loss. The growth fraction of a tumor declines with time, largely due to factors in the microenvironment and accumulation of genetic damage over time. The growth fraction of the first malignant cell is 100%, and by the time a patient presents for medical care, the growth fraction is estimated to be <5%, although the fraction varies between different types of cancers and even different cancers of the same type in different individuals. This fraction is often similar to the growth fraction of normal bone marrow and normal intestinal epithelium, the most highly proliferative normal tissues in the human body, a fact that may explain the dose-limiting toxicities to these tissues of agents that target dividing cells. CHAPTER 77 Cancer Cell Biology The implication of these data is that the tumor is slowing its own growth over time. How does it do this? The tumor cells have multiple genetic lesions that tend to promote proliferation, yet by the time the tumor is clinically detectable, its capacity for proliferation has declined. Better understanding of how a tumor slows its own growth would provide important clues for better cancer treatment. A number of fac­ tors, including those in the tumor microenvironment, are known to contribute to the decreased proliferation of tumor cells over time in the patient. For example, normal cells and other factors in the micro­ environment can contribute to slowing down the growth of cancer cells. Some cancer cells are hypoxemic and have inadequate supply of nutrients and energy. Some have sustained too much genetic damage to complete the cell cycle but have lost the capacity to undergo apoptosis and therefore survive but do not proliferate. However, an important subset is not actively dividing but retains the capacity to divide and can start dividing again under certain conditions such as when the tumor mass is reduced by treatments leading to improved conditions in the tumor microenvironment favorable for cell proliferation. Just as the bone marrow increases its rate of proliferation in response to bone marrow–damaging agents, the tumor also seems to sense when tumor cell numbers have been reduced and can respond by increasing growth rate. However, the critical difference is that the marrow stops growing when it has reached its production goals, whereas tumors do not. The ultimate structure and organization of an organ are based on a number of factors including growth, migration, elimination, and death of various cells; communication between cells to establish the correct architecture; competition between cells; and the composition of the extracellular matrix that is produced. In addition to normal cells stopping proliferation in an organ when that is appropriate, normal tissues have various mechanisms for eliminating cells in both the pro­ cess of development as well as ongoing homeostasis of an organ. These include mechanical processes based on a number of factors including cell size, cell shape, and topology between cells that can determine cell fate as well as an active process of cell extrusion, which plays a major role in the elimination of both cells that are no longer needed by the organ and cells that are damaged and potentially dangerous (such as those with mutations that might be precursors for malignancy). The process of cell extrusion may depend on cell cycle arrest in the S phase; aberrations in this process may contribute to the metastatic process. A variety of processes, including major alterations in cell cycle control, apoptosis and other mechanisms of cell death, and uncontrolled cell signaling, all contribute to defects in appropriate cell extrusion contrib­ uting to the development of cancer. Additional tumor cell vulnerabilities are likely to be detected when we learn more about how normal cells respond to “stop” signals from their environment, and why and how tumor cells and tissues fail to heed such signals. ■ ■CELL CYCLE CHECKPOINTS The cell division cycle consists of four phases—G1 (growth and preparation for DNA synthesis), S (DNA synthesis), G2 (preparation to divide), and M (mitosis, cell division). Cells can also exit the cell cycle and be quiescent (G0). Progression of a cell through the cell cycle is tightly regulated at a number of checkpoints (especially at the G1/S boundary, the G2/M boundary, and during M [spindle checkpoint]) by an array of genes that are targeted by specific genetic alterations in cancer. These checkpoints are quality-control features; at G1, the check­ point does not allow cells to proceed that are not ready for genome replication; at G2/M, the cell assesses whether the genome has been appropriately duplicated and is ready to divide. Critical proteins in these control processes that are frequently mutated or otherwise inacti­ vated in cancers are called tumor-suppressor genes because when they function normally, they inhibit the development or growth of cancer cells. Examples include p53 and Rb (discussed below). PART 4 Oncology and Hematology In the first phase, G1, preparations are made to replicate the genetic material. The cell stops before entering the DNA synthesis phase, or S phase, to take inventory. Are we ready to replicate our DNA? Is the DNA repair machinery in place to fix any mutations that are detected? Are the DNA replicating enzymes available? Is there an adequate supply of nucleotides? Is there sufficient energy to proceed? The reti­ noblastoma protein, Rb, plays a central role in placing a brake on the process until the cell is ready. When the cell determines that it is pre­ pared to move ahead, sequential activation of cyclin-dependent kinases (CDKs) results in the inactivation of the brake, Rb, by phosphorylation. Phosphorylated Rb releases the S phase–regulating transcription factor, E2F/DP1, and genes required for S-phase progression are expressed. If the cell determines that it is unready to move ahead with DNA replica­ tion, a number of inhibitors are capable of blocking the action of the CDKs, including p21Cip2/Waf1, p16Ink4a, and p27Kip1. Nearly every cancer has one or more defects in the G1 checkpoint that permit pro­ gression to S phase despite abnormalities in DNA repair machinery or other deficiencies that would affect normal DNA synthesis. At the end of the G2 phase and before the M phase, after the cell has exactly duplicated its DNA content, a second inventory is taken at the G2 checkpoint. Have all of the chromosomes been fully duplicated? Were all segments of DNA copied only once? Has all damaged DNA been repaired? Do we have the right number of chromosomes and the right amount of DNA? If so, the cell proceeds to G2, in which the cell prepares for division by synthesizing mitotic spindle and other proteins needed to produce two daughter cells. If DNA damage is detected, the p53 pathway is normally activated. Called the guardian of the genome, p53 is a transcription factor that is normally present in the cell in very low levels. This level is generally regulated through its rapid turnover. Normally, p53 is bound to mdm2, a ubiquitin ligase that both inhibits p53 transcriptional activation and also targets p53 for degradation in the proteasome. When DNA damage is sensed, the ATM (ataxiatelangiectasia mutated) pathway is activated; ATM phosphorylates 1. DNA DAMAGE CHECKPOINT 2. ONCOGENE CHECKPOINT myc, E2F, EIA ATM/ATR p53 mdm2 chk1/chk2 Induction of P14ARF P mdm2 P14ARF mdm2 P P Transcriptional activation of p53responsive genes P P p53 Tetramer FIGURE 77-1  Induction of p53 by the DNA damage and oncogene checkpoints. In response to noxious stimuli, p53 and mdm2 are phosphorylated by the ataxiatelangiectasia mutated (ATM) and related ATR serine/threonine kinases, as well as the immediate downstream checkpoint kinases, Chk1 and Chk2. This causes dissociation of p53 from mdm2, leading to increased p53 protein levels and transcription of genes leading to cell cycle arrest (p21Cip1/Waf1) or apoptosis (e.g., the proapoptotic Bcl-2 family members Noxa and Puma). Inducers of p53 include hypoxemia, DNA damage (caused by ultraviolet radiation, gamma irradiation, or chemotherapy), ribonucleotide depletion, and telomere shortening. A second mechanism of p53 induction is activated by oncogenes such as Myc, which promote aberrant G1/S transition. This pathway is regulated by a second product of the Ink4a locus, p14ARF (p19 in mice), which is encoded by an alternative reading frame (ARF) of the same stretch of DNA that codes for p16Ink4a. Levels of ARF are upregulated by Myc and E2F, and ARF binds to mdm2 and rescues p53 from its inhibitory effect. This oncogene checkpoint leads to the death or senescence (an irreversible arrest in G1 of the cell cycle) of renegade cells that attempt to enter S phase without appropriate physiologic signals. Senescent cells have been identified in patients whose premalignant lesions harbor activated oncogenes, for instance, dysplastic nevi that encode an activated form of BRAF (see below), demonstrating that induction of senescence is a protective mechanism that operates in humans to prevent the outgrowth of neoplastic cells. mdm2, releasing it from its inhibitory bond to p53. p53 then stops cell cycle progression, directs the synthesis of repair enzymes, or if the damage is too great, initiates apoptosis (programmed cell death) of the cell to prevent the propagation of a damaged cell (Fig. 77-1). A second method of activating p53 involves the induction of p14ARF by hyperproliferative signals from oncogenes. p14ARF com­ petes with p53 for binding to mdm2, allowing p53 to escape the effects of mdm2 and accumulate in the cell. p53 then stops cell cycle progres­ sion by activating CDK inhibitors such as p21 and/or initiating the apoptosis pathway. Not surprisingly given its critical role in control­ ling cell cycle progression, mutations in the gene for p53 on chromo­ some 17p are among the most frequent mutations in human cancers, although percentages vary between different cancers. Most commonly these mutations are acquired in the malignant tissue in one allele and the second allele is inactivated (such as by deletion or epigenetic silencing), leaving the cell unprotected from DNA-damaging agents or activated oncogenes. Some environmental exposures produce signature mutations in p53; for example, aflatoxin exposure leads to mutation of arginine to serine at codon 249 and leads to hepatocellular carcinoma. In rare instances, p53 mutations are in the germline (Li-Fraumeni syndrome) and pro­ duce a familial cancer syndrome. Another mechanism for inactivation of p53 in malignant cells is due to alterations in regulators such as overexpression of the inhibitory mdm2 protein. Whether inactivated by mutation or inhibited by regulatory factors, absence of normal p53 function leads to chromosomal instability and accumulation of DNA damage including acquisition of properties that give the abnormal cell a proliferative and survival advantage. Like Rb dysfunction, most can­ cers have mechanisms that disable the p53 pathway. Indeed, the impor­ tance of p53 and Rb in the development of cancer is underscored by the neoplastic transformation mechanism of human papillomavirus. This virus has two main oncogenes, E6 and E7. E6 acts to increase the rapid turnover of p53, and E7 acts to inhibit Rb function; inhibition of these two targets is required for transformation of epithelial cells by the virus. Another cell cycle checkpoint exists when the cell is undergoing division (M phase); this is the spindle checkpoint, which acts to ensure that there is proper attachment of chromosomes to the mitotic spindle before progression through the cell cycle can occur. If the spindle apparatus does not properly align the chromosomes for division, if the chromosome number is abnormal (i.e., greater or less than 4n), or if the centromeres are not properly paired with their duplicated partners, then the cell initiates a cell death pathway to prevent the production of aneuploid progeny (having an altered number of chromosomes). Abnormalities in the spindle checkpoint facilitate the development of aneuploidy, which is frequently found in cancers. In some tumors, aneuploidy is a predominant genetic feature. In other tumors, a defect in the cells’ ability to repair errors in the DNA, such as due to mutations in genes coding for the proteins critical for mismatched DNA repair, is the primary genetic lesion. Cancer cells can have defects in any of several DNA repair pathways in addition to mismatch repair, including deficient interstrand cross-link, doublestrand breaks (homologous recombination or nonhomologous end joining repair), single-strand breaks, base excision, nucleotide excision, and translesional synthesis. In general, tumors have either defects in chromosome number or defective DNA repair pathways but not both. Defects that lead to can­ cer include abnormal cell cycle checkpoints, inadequate DNA repair, and failure to preserve genome integrity leading to DNA damage. These defects and the stress of the resultant increased DNA damage make cancer cells more vulnerable to additional DNA damage, which can be exploited by chemotherapy, radiation therapy, targeted therapy, and immunotherapy—the major systemic therapeutic approaches effective against cancer. Alternatively, research is ongoing in an attempt to therapeutically restore the defects in cell cycle regulation and DNA repair that charac­ terize cancer, although this remains a challenging problem because it is much more difficult to restore normal biologic function than to inhibit abnormal function of proteins driving cell proliferation, such as occurs with activated oncogenes. Newer approaches to gene editing (e.g., clustered regularly interspaced short palindromic repeats [CRISPR]) and subsequent modifications to this approach should eventually make gene editing more clinically feasible. ■ ■CELLULAR SENESCENCE The irreversible cessation of growth of normal cells while the cells remain viable has been termed cellular senescence. Senescence is important for several processes involved in normal development and homeostasis including embryogenesis and wound healing. It is also an important component of host mechanisms to prevent tumorigenesis by preventing replication of abnormal cells as well as other mechanisms including secreted substances that can stimulate an immune response against the abnormal senescent cell. However, paradoxically, senescent cells in tumors can also stimulate tumorigenesis and malignant pro­ gression, in part by other secreted substances that stimulate a harmful inflammatory response. It was initially identified by the fact that when normal cells are placed in culture in vitro, most are not capable of sus­ tained growth. They quickly reach a point where they either undergo cell death due to excessive DNA damage or other factors or they become senescent. Fibroblasts are an exception to this rule. When they are cultured, fibroblasts may divide 30–50 times and then they undergo what has been termed a “crisis” during which the majority of cells stop dividing (usually due to an increase in p21 expression, a CDK inhibi­ tor). This form of senescence is termed replicative senescence. Many other cells die, and a small fraction emerge that have acquired genetic and epigenetic changes that permit their uncontrolled growth. Among the cellular changes during in vitro propagation is telomere shorten­ ing. DNA polymerase is unable to replicate the tips of chromosomes, resulting in the loss of DNA at the specialized ends of chromosomes (called telomeres) with each replication cycle. At birth, human telo­ meres are 15- to 20-kb pairs long and are composed of tandem repeats of a six-nucleotide sequence (TTAGGG) that associate with specialized telomere-binding proteins to form a T-loop structure that protects the ends of chromosomes from being mistakenly recognized as damaged. The loss of telomeric repeats with each cell division cycle causes grad­ ual telomere shortening, leading to growth arrest when one or more critically short telomeres trigger a p53-regulated DNA-damage check­ point response. Cell death usually ensues when the unprotected ends of chromosomes lead to chromosome fusions or other catastrophic DNA rearrangements. Cells with certain abnormalities, such as those with nonfunctional pRb and p53, can bypass this growth arrest. The ability to bypass telomere-based growth limitations is thought to be a critical step in the evolution of most malignancies. This occurs by reactivation of telomerase expression in cancer cells. Telomerase is an enzyme that adds TTAGGG repeats onto the 3′ ends of chromosomes. It contains a catalytic subunit with reverse transcriptase activity (hTERT) and an RNA component that provides the template for telomere extension. Most normal somatic cells do not express sufficient telomerase to prevent telomere attrition with each cell division. Exceptions include stem cells (such as those found in hematopoietic tissues, gut and skin epithelium, and germ cells) that require extensive cell division to maintain tissue homeostasis. More than 90% of human cancers express high levels of telomerase that prevent telomere shortening to critical levels and allow indefinite cell proliferation. In vitro experi­ ments indicate that inhibition of telomerase activity leads to tumor cell apoptosis. Major efforts are underway to develop methods to inhibit telomerase activity in cancer cells. For example, the protein component of telomerase (hTERT) may act as one of the most widely expressed tumor-associated antigens and can be targeted by vaccine approaches. However, a caveat to targeting telomerase for anticancer treatment is the potential for inhibiting its activity in certain normal cells (such as stem cells) required for maintaining the normal physiologic state. CHAPTER 77 Cancer Cell Biology Although most of the functions of telomerase relate to cell division, it also has several other effects including interfering with the differenti­ ated functions of at least certain stem cells. However, the impact on dif­ ferentiated function of normal nonstem cells is less clear. The picture is further complicated by the fact that rare genetic defects in the telom­ erase enzyme seem to cause dyskeratosis congenita (characterized by abnormalities in various rapidly dividing cells in the body including skin, nails, oral mucosa, hair, and bone marrow with increased risk for leukemia and certain other cancers). This can be associated with a number of other abnormalities including pulmonary fibrosis, bone marrow failure (aplastic anemia), or liver fibrosis. However, paradoxi­ cally, defects in nutrient absorption in the gastrointestinal tract, a site that should be highly sensitive to defective cell proliferation, are not seen. Much remains to be learned about how telomere shortening and telomere maintenance are related to human illness in general and cancer in particular. A variety of other stresses on cells (both environmental and intrin­ sic including radiation, chemotherapy, reactive oxygen species, and oncogenic mutations) can also lead to senescence, primarily those that induce DNA damage similar to that seen in cells with shortened telo­ meres. This is termed replicative senescence. ■ ■SIGNAL TRANSDUCTION PATHWAYS IN CANCER CELLS Signals that affect cell behavior come from adjacent cells, the stroma in which the cells are located, hormonal signals that originate remotely, and the cells themselves (autocrine signaling). These signals generally exert their influence on the receiving cell through activation of signal transduction pathways that have as their end result the induction of activated transcription factors that mediate a change in cell behavior or function or the acquisition of effector machinery to accomplish a new task. Although signal transduction pathways can lead to a wide variety of outcomes, many such pathways rely on cascades of signals that sequentially activate different proteins or glycoproteins and lipids or glycolipids, and the activation steps often involve the addition or removal of one or more phosphate groups on a downstream target. Other chemical changes can result from signal transduction path­ ways, but reversible phosphorylation and dephosphorylation play a major role. Proteins that add phosphate groups to other molecules (proteins, lipids, or nucleic acids) are called kinases. Two major classes of kinases involved in signal transduction pathways important for can­ cer cells are tyrosine kinases that phosphorylate tyrosine and serine/ threonine kinases that phosphorylate serine/threonine either directly or indirectly. However, some kinases can phosphorylate both, such as the MEK kinases that can phosphorylate both threonine and tyro­ sine. Phosphatases (protein tyrosine phosphatases and protein serine/ threonine phosphatases) remove the phosphate groups to reverse the kinase activity. Various kinases play critical roles in signal transduction pathways important for malignant cells. These include a number of recep­ tor tyrosine kinases (RTKs) as well as various protein kinases (both tyrosine and serine/threonine kinases) downstream of receptors that transmit the signals within the cell (Fig. 77-2). Two important signal­ ing pathways are the RAS-RAF-MEK-ERK pathway and the phospha­ tidylinositol-3-kinase (PI3K) pathway (Fig. 77-2). Although pathways are depicted as distinct, complex interactions between pathways occur within cells. Normally, kinase activity is short-lived and reversed by protein phosphatases. However, in many human cancers, RTKs or compo­ nents of their downstream pathways are activated by mutation, gene PART 4 Oncology and Hematology PI3K inhibitors PIP2 RAS Grb2/mSOS PI3K PIP3 PDK1 AKT Multiple targets Everolimus mTOR Protein synthesis p70S6k ERK1/2 Activated transcription factors ECM Integrin receptor Cytoskeleton FAK c-Src Activated kinases STAT Midostaurin JAK inhibitors JAK PKC Multiple targets PLC-γ Ca2+ Tamoxifen SERMS PIP2 DAG FIGURE 77-2  Therapeutic targeting of signal transduction pathways in cancer cells. Three major signal transduction pathways are activated by receptor tyrosine kinases (RTKs). 1. The protooncogene Ras is activated by the Grb2/mSOS guanine nucleotide exchange factor, which induces an association with Raf and activation of downstream kinases (MEK and ERK1/2). 2. Activated PI3K phosphorylates the membrane lipid PIP2 to generate PIP3, which acts as a membrane-docking site for a number of cellular proteins including the serine/threonine kinases PDK1 and Akt. PDK1 has numerous cellular targets, including Akt and mTOR. Akt phosphorylates target proteins that promote resistance to apoptosis and enhance cell cycle progression, while mTOR and its target p70S6K upregulate protein synthesis to potentiate cell growth. 3. Activation of PLC-γ leads the formation of diacylglycerol (DAG) and increased intracellular calcium, with activation of multiple isoforms of PKC and other enzymes regulated by the calcium/ calmodulin system. Other important signaling pathways involve non-RTKs that are activated by cytokine or integrin receptors. Janus kinases (JAK) phosphorylate STAT (signal transducer and activator of transcription) transcription factors, which translocate to the nucleus and activate target genes. Integrin receptors mediate cellular interactions with the extracellular matrix (ECM), inducing activation of FAK (focal adhesion kinase) and c-Src, which activate multiple downstream pathways, including modulation of the cell cytoskeleton. Many activated kinases and transcription factors migrate into the nucleus, where they regulate gene transcription, thus completing the path from extracellular signals, such as growth factors, to a change in cell phenotype, such as induction of differentiation or cell proliferation. The nuclear targets of these processes include transcription factors (e.g., Myc, AP-1, and serum response factor) and the cell cycle machinery (cyclin-dependent kinases [CDKs] and cyclins). Inhibitors of many of these pathways have been developed for the treatment of human cancers. Examples of inhibitors that are either approved or are currently being evaluated in clinical trials are shown in purple type. amplification, or chromosomal translocations to have enhanced and/ or prolonged activity. Because these pathways are important in regulat­ ing proliferation, survival, migration, and angiogenesis, they have been identified as important targets for cancer therapeutics. Inhibition of kinase activity is effective in the treatment of a number of neoplasms. Lung cancers with mutations in the epidermal growth factor receptor are highly responsive to osimertinib as well as other inhibitors (Table 77-2). Inhibitors have been developed to treat lung cancers with other tyrosine kinase–activating mutations (including anaplastic lymphoma kinase [ALK], ROS1, NTRK, MET, HER2, and RET). BRAF (a serine/threonine kinase) inhibitors are highly effective in melanomas and thyroid cancers and are also used in combination with other agents for lung and colon cancers as well as other solid tumors with BRAF V600E mutations. Targeting the MEK protein (which phosphorylates both threonine and tyrosine residues) down­ stream of BRAF also has activity against BRAF mutant melanomas, and combined inhibition of BRAF and MEK is more effective than either alone with activity that extends to BRAF-mutant lung cancer. Janus kinase (JAK) inhibitors are active in myeloproliferative syn­ dromes in which JAK2 activation is a pathogenetic event. Imatinib (which targets a number of tyrosine kinases) is an effective agent in Ligand RTK Monoclonal antibody Under investigation Tyrosine kinase inhibitors Raf kinase inhibitors RASC inhibitors Raf GAP MEK inhibitors MEK ERK inhibitors Multiple cytoplasmic targets AP-1 (Jun/Fos) Serum response factor MYC Cyclin D1 CDK/cyclin complexes CDK H/b inhibitors Cell cycle regulation Nucleus Estrogen receptor TABLE 77-2  Some FDA-Approved Molecularly Targeted Agents for the Treatment of Cancer DRUG MOLECULAR TARGET DISEASE MECHANISM OF ACTION All-trans retinoic acid PML-RARα oncogene Acute promyelocytic leukemia M3 AML, t(15;17) Imatinib, dasatinib, nilotinib, ponatinib, bosutinib Bcr-Abl, c-Abl, c-Kit, PDGFR-α/β Chronic myeloid leukemia, GIST Blocks ATP binding to tyrosine kinase active site Ripretinib c-Kit, PDGFR-α GIST Inhibits tyrosine kinase activity Asciminib Bcr-Abl Chronic myeloid leukemia Allosteric inhibitor of BCR-ABL Sunitinib c-Kit, VEGFR-2, PDGFR-β, Flt-3 GIST, RCC, PNET Inhibits activated c-Kit and PDGFR in GIST; inhibits VEGFR in RCC and probably in PNET Sorafenib RAF, VEGFR-2, PDGFR-α/β, Flt-3, c-Kit RCC, hepatocellular carcinoma (HCC), differentiated thyroid cancer, desmoid Regorafenib VEGFR1–3, TIE-2, FGFR1, KIT, RET, PDGFR Colorectal cancer, GIST, HCC Competitive inhibitor ATP binding site of tyrosine kinase domain multiple kinases including VEGFR Larotrectinib, entrectinib NTRK Cancers with NTRK mutation Competitive inhibitor of ATP binding site of the tyrosine kinase domain of NTRK Axitinib VEGFR1–3 RCC Competitive inhibitor ATP binding site of tyrosine kinase domain VEGF receptors Erlotinib EGFR NSCLC, pancreatic cancer Competitive inhibitor of the ATP-binding site of the EGFR Afitinib EGFR (and other HER family) NSCLC Irreversible inhibitor of ATP-binding site of HER family members Osimertinib EGFR (T790M) NSCLC Inhibits EGFR mutations including T790M mutant NSCLC Dacomitinib EGFR NSCLC (exon19 deletion/exon 21 L858R) Inhibits EGFR mutant lung cancer Mobocertinib/EGFR/NSCLC/Tumors with Exon20 insertion mutations Erdafitinib, pemigatinib, futibatinib, infigratinib FGFR2, FGFR3 Urothelial (erdafitinib), myeloid/ lymphoid neoplasms (pemigatinib) cholangiocarcinoma (pemigatinib, futibatinib) Lapatinib, tucatinib, niratinib HER2/neu Breast cancer, CRC (tucatinib + trastuzumab) Crizotinib, ceritinib, alectinib, brigatinib, lorlatinib ALK NSCLC ALK+ large cell lymphoma, inflammatory myofibroblastic tumors (crizotinib) Crizotinib, entrectinib repotrectinib ROS1 NSCLC Inhibitor of ROS1 tyrosine kinase Palbociclib, ribociclib, abemaciclib CDK4/6 Breast Inhibitor of CDK4/6 Bortezomib, carfilzomib, ixazomib Proteasome Multiple myeloma Inhibits proteolytic degradation of multiple cellular proteins Vemurafenib, dabrafenib Encorafenib BRAF V600E Melanoma lung cancer, CRC (combined with Cetuximab) Trametinib, Cobimetinib, binimetinib MEK Melanoma Inhibitor of serine-threonine kinase domain of MEK Cabozantinib RET, MET, VEGFR MTC, RCC Competitive inhibitor of ATP-binding site of tyrosine kinase domain of multiple kinases, including VEGFR2 and RET Capmatinib, tepotinib MET NSCLC with MET exon14 deletions   Selpercatinib, vandetinib, pralsetinib RET NSCLC, MTC, RET fusion thyroid cancer, RET fusion positive solid tumors Temsirolimus mTOR RCC Competitive inhibitor of mTOR serine-threonine kinase Everolimus mTOR RCC, PNET Binds to immunophilin FK binding protein-12, which forms a complex that inhibits mTOR kinase Vorinostat, romidepsin, belinostat HDAC CTCL/PTL HDAC inhibitor, epigenetic modulation Panobinostat HDAC MM HDAC inhibitor, epigenetic modulation Ruxolitinib JAK-1, 2 Myelofibrosis Competitive inhibitor of tyrosine kinase Vismodegib Hedgehog pathway Basel cell cancer (skin) Inhibits smoothened in hedgehog pathway Lenvatinib Multikinase inhibitor (VEGFR, FGFR, PGFR-α, others) RCC, thyroid cancer, HCC Competitive inhibitor of ATP-binding site of tyrosine kinase domain of multiple kinases Olaparib, rucaparib, niraparib, talazoparib PARP BRCA mutant ovarian, breast, prostate, pancreas cancers; not all agents approved for all cancers Venetoclax BCL-2 CLL (with 17p deletion) Inhibits BCL-2 and enhances apoptosis Ibrutinib, acalabrutinib pirtobrutinib, zanubrutinib Bruton tyrosine kinase (BTK) CLL, MCL, MZL, SLL, WM Inhibitor of BTK Inhibits transcriptional repression by PML-RARα Adagrasib, Solorasib/KRAS12C/NSCLC/Inhibits KRAS12C Targets VEGFR pathways in RCC and HCC. Possible activity against BRAF in thyroid cancer CHAPTER 77 Inhibits tyrosine kinase of FGFR Cancer Cell Biology Competitive inhibitor of the ATP-binding site of HER2 Inhibitor of ALK tyrosine kinase Inhibitor of serine-threonine kinase domain of V600E mutant of BRAF Inhibitor of RET, VEGFR1, VEGFR2 tyrosine kinases Inhibits PARP and DNA repair (Continued) TABLE 77-2  Some FDA-Approved Molecularly Targeted Agents for the Treatment of Cancer DRUG MOLECULAR TARGET DISEASE MECHANISM OF ACTION Ivosidenib, olutasidenib IDH1 AML, MDS, cholangiocarcinoma IDH1 inhibitor Gilteritinib, quizartinib FLT3 AML FLT3 inhibitor Idelalisib PI3K-delta CLL Inhibits PI3k-delta, preventing proliferation and inducing apoptosis Alpelisib PIK3CA Breast cancer with a PIK3CA mutation Inhibits PIK3CA Belzutifan Hif-2α HIF-1α-associated RCC, pancreatic neuroendocrine, CNS hemangioblastoma Capivasertib AKT Breast cancer Inhibits AKT Umbralisib PI3K-delta, CK1-epsilon MZL, FL Inhibits PI3K-delta and CK1-epsilon Selinexor Exportin-1 MM, DLBCL Induces apoptosis of cells Tazemetostat EZH2 FL, epithelioid sarcoma Inhibits EZH2 Monoclonal Antibodies Trastuzumab, margetuximab HER2/neu (ERBB2) Breast cancer, gastric or GEJ cancer Binds HER2 on tumor cell surface and induces receptor internalization Pertuzumab HER2/neu (ERBB2) Breast cancer Binds HER2 on tumor cell surface at distinct site from trastuzumab and prevents binding to other receptors Cetuximab EGFR Colon cancer, squamous cell carcinoma of the head and neck PART 4 Oncology and Hematology Panitumumab EGFR Colon cancer Similar to cetuximab but fully humanized rather than chimeric Necitumumab EGFR Squamous NSCLC Binds EGFR Rituximab CD20 B-cell lymphomas and leukemias that express CD20 Alemtuzumab CD52 Chronic lymphocytic leukemia and CD52expressing lymphoid tumors Bevacizumab VEGF Colorectal, lung cancers, RCC, glioblastoma Inhibits angiogenesis by high-affinity binding to VEGF Ziv-aflibercept VEGFA, VEGFB, PLGF Colorectal cancers Inhibits angiogenesis by high-affinity binding to VEGFA, VEGFB, and PLGF Ramucirumab VEGFR Gastric, colorectal, lung cancers Inhibits angiogenesis by binding to VEGFR Ipilimumab CTLA-4 Melanoma, HCC, MSI-high colorectal cancer Blocks CTLA-4, preventing interaction with CD80/86 and T-cell inhibition Nivolumab, pembrolizumab, dostarlimab-gxly, toripalimab, retifanlimab-dlwr, cemiplimab-rwlc PD-1 Melanoma, head and neck cancer, NSCLC, SCLC, Hodgkin’s disease, urothelial cancer, RCC, HCC, gastric cancer, esophageal cancer, cholangiocarcinoma, MSI-high cancers, endometrial cancer, cervical cancer, cutaneous squamous cell carcinoma, basal cell carcinoma, breast cancer, nasopharyngeal cancer, Merkel cell tumor Atezolizumab, durvalumab, avelumab PD-L1 NSCLC, urothelial cancer, SCLC (durvalumab), HCC (atezolizumab), Merkel cell cancer (avelumab) Relatlimab LAG3 Melanoma (combined with nivolumab) Blocks LAG3 interaction with MHCII and other ligands inhibiting immune activation Denosumab Rank ligand Breast, prostate Inhibits Rank ligand, primary signal for bone removal Dinutuximab Glycolipid GD2 Neuroblastoma (pediatric) Immune-mediated attack on GD2-expressing cells Daratumumab, Isatuximab CD38 MM Binds to CD38 on MM cells causing apoptosis by antibody-dependent or compliment-mediated cytotoxicity Elotuzumab SLAMF7 MM Activating NK cells to kill MM cells Olaratumab PDGFRα Soft tissue sarcomas Blocks PDGFRα activity Naxitamab GD2 Neuroblastoma Immune-mediated antitumor effect Bispecific Antibodies Blinatumomab CD19 and CD3 Ph-relapsed precursor B-cell ALL Binds CD19 on ALL cells and CD3 on T cells; immune attack on CD19-expressing cells Glofitamab-gxbm, epcoritamabbysp, mosunetuzumab-axgb CD20 and CD3 DLBCL, FL Binds CD20 on DLBCL or FL and CD3 on T cells, immune attack on CD20-expressing cells Teclistamab-cqyv, elranatamab-bcmm B-cell maturation antigen (BCMA) and CD3 MM Binds BCMA on MM cells and CD3 on T cells Talquetamab CD3 and GPRC5D MM Binds CD3 T cells and GPRC5D-expressing MM cells (Continued) Inhibits Hif-2α Binds extracellular domain of EGFR and blocks binding of EGF and TGF-α; induces receptor internalization. Potentiates the efficacy of chemotherapy and radiotherapy Multiple potential mechanisms, including direct induction of tumor cell apoptosis and immune mechanisms Immune mechanisms Blocks PD-1, preventing interaction with PD-L1 and T-cell inhibition Blocks PD-L1, preventing interaction with PD-1 and T-cell inhibition (Continued) TABLE 77-2  Some FDA-Approved Molecularly Targeted Agents for the Treatment of Cancer DRUG MOLECULAR TARGET DISEASE MECHANISM OF ACTION Amivantamab-vmjw EGFR and MET NSCLC Targets EGFR exon 20 insertion mutations by also inhibiting MET Tebentafusp-tebn GP100 and CD3 Uveal melanoma Binds GP100 on melanoma cells and CD3 on T cells Antibody-Chemotherapy Conjugates Brentuximab vedotin CD30 Hodgkin’s disease, anaplastic lymphoma Delivers chemotherapeutic agent MMAE to CD30-expressing Ado-trastuzumab emtansine HER2 Breast cancer Delivers chemotherapeutic agent emtansine to HER2-expressing breast cancer cells Fam-trastuzumab HER2 Breast, NSCLC, and gastric cancers Delivers chemotherapeutic agent deruxtecan to HER2-expressing breast cancer cells Sacituzumab govitecan Trop2 Breast, urothelial cancers Delivers chemotherapy to Trop2-expressing cells Enfortumab-vedotin Nectin-4 Urothelial cancers Delivers chemotherapeutic agent MMAE to Nectin-4-expressing cells Polatuzumab-vedotin CD79b DLBCL or high-grade BCL Delivers MMAE chemotherapy to B-cell lymphomas Loncastuximab tesirine-lpyl CD19 DLBCL Delivers chemotherapy to CD19 expressing cells Mirvetuximab soravtansine-gynx Folate receptor alpha Ovarian, fallopian, peritoneal cancers Delivers chemotherapy to folate receptor alpha tumors Tisotumab vedotin-tftv Tissue factor (TF) Cervical cancer Delivers chemotherapy to TF-positive cells Gemtuzumab ozogamicin CD33 Pediatric CD33+ AML Delivery of chemotherapy to CD33+ cells CAR-T Cells and Tumor-Infiltrating Lymphocyte (TIL) Tisagenlecleucel, axicabtagene ciloleucel, brexucabtagene autoleucel, lisocabtagene maraleucel CD19 ALL (tisagenlecleucel), DLBCL/highgrade BCL (axicabtagene ciloleucel), B-cell precursor ALL (brexucabtagene), large BCL (lisocabtagene maraleucel) Ciltacabtagene autoleucel Idecabtagene vicleucel BCMA MM Targets T cells to protein on surface of MM cells Lifileucel Melanoma antigens Melanoma Tumor-infiltrating lymphocyte therapy Abbreviations: ALL, acute lymphocytic leukemia; AML, acute myeloid leukemia; BCL, B-cell lymphoma; CAR-T, chimeric antigen receptor T cells; CLL, chronic lymphocytic leukemia; CRC, colorectal cancer; CTCL, cutaneous T cell lymphoma; DLBCL, diffuse large B-cell lymphoma; EGFR, epidermal growth factor receptor; FDA, U.S. Food and Drug Administration; FGFR, fibroblast growth factor receptor; FL, follicular lymphoma; Flt-3, fms-like tyrosine kinase-3; GEJ, gastroesophageal junction; GIST, gastrointestinal stromal tumor; HDAC, histone deacetylases; MCL, mantle cell lymphoma; MM, multiple myeloma; MSI, microsatellite instability; MMAE, monomethyl auristatin E; MTC, medullary thyroid cancer; mTOR, mammalian target of rapamycin; MZL, mantle zone lymphoma; NK, natural killer; NSCLC, non-small-cell lung cancer; PARP, poly-ADP ribose polymerase; PDGFR, platelet-derived growth factor receptor; PLGF, placenta growth factor; PML-RARα, promyelocytic leukemia–retinoic acid receptor-alpha; PNET, pancreatic neuroendocrine tumors; PTL, peripheral T-cell lymphoma; RCC, renal cell cancer; t(15;17), translocation between chromosomes 15 and 17; SCLC, small-cell lung cancer; SLL, small lymphocytic lymphoma; TGF-α, transforming growth factor-alpha; VEGFR, vascular endothelial growth factor receptor; WM, Waldenström’s macroglobulinemia. Note: The pace of drug discovery is rapid and this list is not comprehensive. tumors that have translocations of the c-Abl and BCR gene (such as chronic myeloid leukemia), mutant c-Kit (gastrointestinal stromal cell tumors), or mutant platelet-derived growth factor receptor (PDGFRα; gastrointestinal stromal tumors). Second-generation inhibitors of BCR-Abl, dasatinib and nilotinib, are even more effective, and the third-generation agent bosutinib has activity in some patients who have progressed on other inhibitors, while the third-generation agent ponatinib has activity against the T315I mutation, which is resistant to the other agents. Although almost all tyrosine kinase inhibitors are not entirely selective for one protein, certain inhibitors have significant activity against a broad number of proteins. These include sorafenib, regorafenib, cabozantinib, sunitinib, and lenvatinib. These have shown antitumor activity in various malignancies, including renal cell cancer (RCC) (sorafenib, sunitinib, cabozantinib, lenvatinib), hepatocellular carcinoma (sorafenib, regorafenib, lenvatinib), gastrointestinal stromal tumor (GIST) (sunitinib, regorafenib), thyroid cancer (sorafenib, cabo­ zantinib, lenvatinib), colorectal cancer (regorafenib), and pancreatic neuroendocrine tumors (sunitinib). Inhibitors of the PI3K pathway also have been approved for cancer therapy. The PI3K family includes three classes and several isoforms within each class. Inhibitors against different isoforms have proved effective against different types of malignancies, with inhibitors of the delta isoform (either specifically or also with inhibition of other iso­ forms; e.g., idelalisib) having activity against lymphoid malignancies (CLL), whereas the specific inhibitor of a mutation in the alpha isoform (alpelisib) has activity against breast cancers with this mutation. Inhibi­ tors of mammalian target of rapamycin (mTOR; which is downstream of PI3K; e.g., everolimus, temsirolimus) are active in RCC; welldifferentiated nonfunctional neuroendocrine tumors of pancreatic, (Continued) tumor cells CHAPTER 77 Targeted T cells to protein on surface of malignant cells Cancer Cell Biology gastrointestinal, or lung origin; and breast cancer. Additional inhibitors of the PI3K pathway and other phospholipid signaling pathways such as the phospholipase C-gamma pathway, which are involved in a large number of cellular processes important in cancer development and progression, are being evaluated. The list of active agents and treatment indications is growing rapidly (Table 77-2). These agents have ushered in a new era of personalized therapy. For many cancers, it is now standard for tumor biopsies to be assessed for specific molecular changes that predict response and to have clinical decision-making guided by those results. This is now an important component of choosing therapy for metastatic lung, gas­ troesophageal, melanoma, breast, and colorectal cancers as well as in adjuvant therapy for breast cancer. This list will continue to evolve as both new agents against existing targets are developed and new targets are discovered. An alternative approach to testing samples directly from tumors is to test blood for the presence of mutations or amplification in circulating tumor DNA, which has the significant advantage of being noninvasive. As cancers grow, some of the cells die, break apart, and release cellular contents, including DNA, into the circulation. Sensitive methods have been developed to detect this DNA and to identify mutations and other DNA changes in the malignant cells. This has the potential advantage over tumor biopsies of sampling all of the tumor and not being lim­ ited to one site that may not be representative of the overall tumor heterogeneity. Distinct metastatic lesions may have different genetic abnormalities that will not be detected in a biopsy of a single site. In addition to identifying potential changes that can be targeted for therapy, there is also the potential for monitoring a patient’s response to therapy, identifying resistance mechanisms to therapy earlier, detecting disease recurrence before it can be detected by tumor markers or scans, monitoring bodily fluids in addition to blood, and possibly providing a means of earlier initial detection of cancer if sufficiently sensitive and specific detection methods can be developed. Optimizing the sensitiv­ ity and specificity of these tests is essential for their potential utility in patient care. Research is ongoing to determine if other cellular compo­ nents specific to cancer cells (e.g., mRNA, proteins from mutant genes, or other protein modifications found in cancer cells) might also be useful for diagnosis or monitoring therapeutic response. However, none of these targeted therapies has yet been curative by themselves for any malignancy, although prolonged periods of disease control lasting many years frequently occur in chronic myeloid leuke­ mia (CML), including a >80% survival rate at 10 years, and antibodies to HER2 have increased survival for breast cancer patients in combina­ tion with chemotherapy. The reasons for the failure of targeted agents to cure are not completely defined, although resistance to the treat­ ment ultimately develops in most patients. In some tumors, resistance to kinase inhibitors is related to proliferation of cells with a mutation in the target kinase that inhibits drug binding. Many of these kinase inhibitors act as competitive inhibitors of the ATP-binding pocket. ATP is the phosphate donor in these phosphorylation reactions. For example, mutation in the critical BCR-ABL kinase in the ATP-binding pocket (such as the threonine to isoleucine change at codon 315 [T315I]) can prevent imatinib binding. Other resistance mechanisms include alterations in other signal transduction pathways to bypass the inhibited pathway. As resistance mechanisms continue to be bet­ ter defined, rational strategies to overcome resistance are emerging. In addition, many kinase inhibitors are less specific for an oncogenic target than was hoped, and toxicities related to off-target inhibition of kinases limit the use of the agent at a dose that would optimally inhibit the cancer-relevant kinase. PART 4 Oncology and Hematology Antibodies against protein targets more highly expressed on malig­ nant than normal cells can also be used to deliver highly toxic com­ pounds relatively specifically to cancer cells. Examples of protein targets for currently approved antibody-drug conjugates include CD30 for Hodgkin’s and anaplastic lymphomas; HER2 on breast cancer; CD33 on acute myeloid leukemias; CD22 on B-cell acute lymphocytic and hairy cell leukemias; and CD79b on diffuse large B-cell lymphomas. Another strategy to enhance the antitumor effects of targeted agents is to use them in rational combinations with each other as well as with chemotherapy or immunotherapy agents that kill cells in ways dis­ tinct from agents targeting specific mutant or overexpressed proteins. Combinations of trastuzumab (a monoclonal antibody that targets the HER2 receptor [member of the EGFR family]) with chemotherapy have significant activity against breast, gastric, and esophageal cancers that have high levels of expression of the HER2 protein. The activity of trastuzumab and chemotherapy can be enhanced further by combina­ tions with another targeted monoclonal antibody (pertuzumab), which prevents dimerization of the HER2 receptor with other HER family members including HER3, or in some cases with immunotherapy, such as combinations of chemotherapy, trastuzumab, and the immu­ notherapeutic agent pembrolizumab against HER2-positive gastric and esophageal cancers. Although targeted therapies have not yet resulted in cures when used alone, their use in the adjuvant setting and when combined with other effective treatments has substantially increased the fraction of patients cured. For example, the addition of rituximab, an anti-CD20 antibody, to combination chemotherapy in patients with diffuse large B-cell lymphoma improves cure rates by ~15%. The addition of trastuzumab, an antibody to HER2, to combination chemotherapy in the adjuvant treatment of HER2-positive breast cancer significantly improves overall survival. A major effort continues to develop targeted therapies for mutations in the ras family of genes, which play a critical role in transmitting signals through a number of downstream signaling pathways includ­ ing the MAP (mitogen-activated protein) kinase and PI3K pathways. Mutations in ras are the most common mutations in oncogenes in cancers (especially kras) but have proved to be very difficult targets for a number of reasons related to the structure of RAS proteins as well as mechanisms of activation and inactivation (active when bound to guanosine triphosphate [GTP] and inactive when bound to guanosine diphosphate [GDP]). RAS proteins are not kinases but bind directly to the BRAF serine/threonine kinase with preferential binding when RAS is in the active GTP bound state. Agents that target one of the mutant forms of KRAS (12C), which is the most common RAS muta­ tion in lung cancer and is also found in a subset of other cancers, have sufficient antitumor activity to now be approved for the treatment of these lung cancers. They are under active study (often in combina­ tion with other agents) for the treatment of other cancers that have the KRAS12C mutation. Agents targeting other mutations in the RAS genes (especially other KRAS-mutant proteins) are also being evalu­ ated in clinical trials. One strategy for new drug development is to take advantage of socalled oncogene addiction. This situation (Fig. 77-3) is created when a tumor cell develops an activating mutation in an oncogene that becomes a dominant pathway for survival and growth with reduced contributions from other pathways, even when there may be abnor­ malities in those pathways. This dependency on a single pathway creates a cell that is vulnerable to inhibitors of that oncogene pathway. For example, cells harboring mutations in BRAF are sensitive to MEK inhibitors that inhibit signaling via the BRAF pathway. Proteins critical for transcription of other proteins essential for malignant cell survival or proliferation provide another potential target for treating cancers. The transcription factor nuclear factor (NF)-κB is a heterodimer composed of p65 and p50 subunits that associate with an inhibitor, IκB, in the cell cytoplasm. In response to growth factor or cytokine signaling, a multisubunit kinase called IKK (IκB-kinase) phosphorylates IκB and directs its degradation by the ubiquitin/ proteasome system. NF-κB, free of its inhibitor, translocates to the nucleus and activates target genes, many of which promote the survival of tumor cells. One of the mechanisms by which novel drugs called proteasome inhibitors are thought to produce an anticancer effect is by blocking the proteolysis of IκB, thereby preventing NF-κB activation. For reasons that have not been fully elucidated, this has a differential toxicity effect on tumor, as compared to normal cells. Although this mechanism appears to be an important aspect of the antitumor effects of proteasome inhibitors, other effects involving the inhibition of the degradation of multiple cellular proteins important in malignant cell survival or proliferation also play a role. Proteasome inhibitors (e.g., bortezomib, carfilzomib, ixazomib) have activity in patients with multiple myeloma, including partial and complete remissions. Inhibitors of IKK are also in development, with the hope of more selectively blocking the degradation of IκB, thus “locking” NF-κB in an inhibitory complex and rendering the cancer cell more susceptible to apoptosis-inducing agents. Many other transcription factors are activated by phosphorylation, which can be prevented by tyrosine or serine/threonine kinase inhibitors, a number of which are currently in clinical trials. Estrogen receptors (ERs) and androgen receptors (ARs), members of the steroid hormone family of nuclear receptors, are targets of inhi­ bition by drugs used to treat breast and prostate cancers, respectively. Selective estrogen receptor modulators (SERMs) have been developed as a treatment approach for ER-positive breast cancer. Tamoxifen, a partial agonist and antagonist of ER function, is frequently used in breast cancer, can mediate tumor regression in metastatic breast cancer, and can prevent disease recurrence in the adjuvant setting. Tamoxifen binds to the ER and modulates its transcriptional activity, inhibiting activity in the breast but promoting activity in bone but unfortunately also in uterine epithelium, leading to a small increased risk of uterine cancer. Attempts have been made to develop SERMs that would have antiestrogenic effects in both breast and uterus while maintaining protective effects on bone. However, none of these to date has been an improvement over tamoxifen. Aromatase inhibitors, which block the conversion of androgens to estrogens in breast and subcutaneous fat tissues, have demonstrated improved clinical efficacy compared with tamoxifen in postmenopausal women and are often used as first-line therapy in postmenopausal patients with ER-positive disease. They are occasionally used in premenopausal patients with ER-positive disease Normal cell Base excision repair Tumor cell BRCA1, 2 nonmutated Normal cell Base excision repair Tumor cell BRCA1, 2 mutated FIGURE 77-3  Synthetic lethality. Genes are said to have a synthetic lethal relationship when mutation of either gene alone is tolerated by the cell, but mutation of both genes leads to lethality, as originally noted by Bridges and later named by Dobzhansky. Thus, mutant gene a and gene b have a synthetic lethal relationship, implying that the loss of one gene makes the cell dependent on the function of the other gene. In cancer cells, loss of function of a DNA repair gene like BRCA1, which repairs double-strand breaks, makes the cell dependent on base excision repair mediated in part by PARP. If the PARP gene product is inhibited, the cell attempts to repair the break using the error-prone nonhomologous end-joining method, which results in tumor cell death. High-throughput screens can now be performed using isogenic cell line pairs in which one cell line has a defined defect in a DNA repair pathway. Compounds can be identified that selectively kill the mutant cell line; targets of these compounds have a synthetic lethal relationship to the repair pathway and are potentially important targets for future therapeutics. in combination with ovarian suppression approaches such as lutein­ izing hormone–releasing hormone (LHRH) agonists. A number of approaches have been developed for blocking andro­ gen stimulation of prostate cancer, including decreasing production by the testicles (e.g., orchiectomy, LHRH agonists or antagonists), directly blocking actions of androgen (a number of agents have been developed to do this), or blocking production by inhibiting the enzyme CYP17, which is central in production of androgens from cholesterol. ■ ■CANCER-SPECIFIC GENETIC CHANGES AND SYNTHETIC LETHALITY The concepts of oncogene addiction and synthetic lethality have spurred new drug development targeting oncogene- and tumorsuppressor pathways. As discussed earlier in this chapter and outlined in Fig. 77-3, cancer cells can become dependent upon signaling pathways containing activated oncogenes; this can effect proliferation (i.e., mutated KRAS, BRAF, overexpressed MYC, or activated tyrosine kinases). Additional genetic changes in malignant cells or unique features of tumors including defects in DNA repair (e.g., loss of BRCA1 or BRCA2 gene function), modifications in cell cycle control (e.g., changes in protein levels or mutations in cyclins and CDKs), enhanced survival mechanisms (overexpression of Bcl-2 or NF-κB), altered cell metabolism (such as occurs when mutant KRAS enhances glucose uptake and aerobic glycolysis), tumor-stromal interactions, and angiogenesis (e.g., production of vascular endothelial growth fac­ tor [VEGF] in response to HIF-2α in RCC) can also be successfully exploited to relatively specifically target cancers. However, resistance to inhibition of specific oncogenic pathways almost always eventually develops. In addition, targeting defects in tumor-suppressor genes has been much more difficult, both because the target of mutation is + PARP inhibition PARP PARP PARP PARP PARP PARP PARP PARP Homologous double strand break repair No cell killing CHAPTER 77 Homologous double strand break repair Selective tumor cell killing – Cancer Cell Biology often deleted and because it is much more difficult to restore normal function than to inhibit abnormal function of a protein. Synthetic lethality occurs when loss of function in either of two or more genes individually has limited effects on cell survival but loss of function in both (or more) genes leads to cell death. In the case of oncogeneaddicted pathways, identifying genes that have a synthetic lethal rela­ tionship with the activated pathway may allow enhanced cell killing and decreased resistance by targeting those genes or their proteins. In the case of mutant tumor-suppressor genes, identifying genes that have a synthetic lethal relationship to those mutated pathways may allow targeting by inhibiting proteins required uniquely by those cells for survival or proliferation (Fig. 77-3). This is a much more tractable approach than attempting to repair normal function of the mutant suppressor gene itself. Examples of synthetic lethality with clinical impact have been identified. For instance, cells with mutations in the BRCA1 or BRCA2 tumor-suppressor genes (e.g., a subset of breast and ovarian cancers) are unable to repair DNA damage by homologous recombination. Poly-ADP ribose polymerase (PARP) is a family of proteins important for single-strand break (SSB) DNA repair. PARP inhibition results in selective killing of cancer cells that have lost BRCA1 or BRCA2 function. A number of PARP inhibitors have been approved for treatment of ovarian, breast, and pancreatic cancers with BRCA mutations and are likely to have activity in other tumors with defective DNA repair mechanisms. The concept of synthetic lethality provides a framework for genetic screens to identify other synthetic lethal combinations involving known tumor-suppressor genes and development of novel therapeutic agents to target dependent path­ ways. Other unique aspects of malignant tumors, including those outlined elsewhere in the chapter, may also be vulnerable to synthetic lethal interactions. ■ ■EPIGENETIC INFLUENCES ON CANCER GENE TRANSCRIPTION Chromatin structure regulates the hierarchical order of sequential gene transcription that governs differentiation and tissue homeostasis. Disruption of chromatin remodeling (the process of modifying chro­ matin structure to control exposure of specific genes to transcriptional proteins, thereby controlling the expression of those genes) leads to aberrant gene expression that can significantly alter the biology of cells including inducing proliferation or migration of cells. Epigenetic changes are those that alter the pattern of gene expression that persist across at least one cell division but are not caused by changes in the DNA code. These include alterations of chromatin structure mediated by methylation of cytosine residues of DNA (primarily in context of CpG dinucleotides in somatic cells), modification of histones by alter­ ing acetylation or methylation, or changes in higher-order chromo­ some structure (Fig. 77-4). Appropriate control of DNA methylation is essential for normal cell function and development, and both altered methylation and hypomethylation of histones occur in cancers. Hyper­ methylation of DNA promoter regions is a common mechanism by which tumor-suppressor loci are epigenetically silenced in cancer cells. Thus, one allele of a tumor-suppressor gene may be inactivated by mutation or deletion, while expression of the other allele is epigeneti­ cally silenced, usually by methylation, leading to loss of gene function. Aberrant hypomethylation is also frequently found in a number of cancers consistent with the dysregulated pattern of gene transcription that is a hallmark of cancer cells, with some genes being inappropri­ ately turned off while others are inappropriately turned on. Specific changes in DNA methylation in cancer cells provide a potentially more sensitive and specific approach to utilizing circulating tumor DNA to identify the presence of cancer than utilizing only DNA mutational analysis. PART 4 Oncology and Hematology Acetylation of the amino terminus of the core histones H3 and H4 induces an open chromatin conformation that promotes transcription HDAC MeCP Nucleosomes CpG Island in promoter region HAT: histone acetyl transferase HDAC: histone deacetylase :unmethylated CpG :methylated CpG DNMT: DNA methyltransferase MeCP: methylcytosine binding protein Co-activator complex HAT HAT Tc factor Tc factor Tc factor “Open” chromatin configuration permits binding of multiple sequence-specific transcription factors that cooperatively promote gene expression. Nucleosomes Nucleosomes FIGURE 77-4  Epigenetic regulation of gene expression in cancer cells. Tumor-suppressor genes are often epigenetically silenced in cancer cells. In the upper portion, a CpG island within the promoter and enhancer regions of the gene has been methylated, resulting in the recruitment of methyl-cytosine binding proteins (MeCP) and complexes with histone deacetylase (HDAC) activity. Chromatin is in a condensed, nonpermissive conformation that inhibits transcription. Clinical trials are under way utilizing the combination of demethylating agents such as 5-aza-2′-deoxycytidine plus HDAC inhibitors, which together confer an open, permissive chromatin structure (lower portion). Transcription factors bind to specific DNA sequences in promoter regions and, through protein-protein interactions, recruit coactivator complexes containing histone acetyl transferase (HAT) activity. This enhances transcription initiation by RNA polymerase II and associated general transcription factors. The expression of the tumor-suppressor gene commences, with phenotypic changes that may include growth arrest, differentiation, or apoptosis. initiation. Histone acetylases are components of coactivator complexes recruited to promoter/enhancer regions by sequence-specific transcrip­ tion factors during the activation of genes (Fig. 77-4). Histone deacety­ lases (HDACs; multiple HDACs are encoded in the human genome) are recruited to genes by transcriptional repressors and prevent the initia­ tion of gene transcription. Methylated cytosine residues in promoter regions become associated with methyl cytosine–binding proteins that recruit protein complexes with HDAC activity. The balance between permissive and inhibitory chromatin structure is therefore largely determined by the activity of transcription factors in modulating the “histone code” and the methylation status of the genetic regulatory elements of genes. The pattern of gene transcription is aberrant in all human cancers, and in many cases, epigenetic events are responsible. Epigenetic events play a critical role in carcinogenesis (e.g., long-lasting changes in methylation induced by smoking) and are found in prema­ lignant lesions. Unlike genetic events that alter DNA primary structure (e.g., deletions), epigenetic changes are potentially reversible and appear amenable to therapeutic intervention. In certain human can­ cers, including a subset of pancreatic cancers and multiple myeloma, the p16Ink4a promoter is inactivated by methylation, thus permitting the unchecked activity of CDK4/cyclin D and rendering pRb nonfunc­ tional. In sporadic forms of renal, breast, and colon cancer, the von Hippel–Lindau (VHL), breast cancer 1 (BRCA1), and serine/threonine kinase 11 (STK11) genes, respectively, can be epigenetically silenced. Other targeted genes include the p15Ink4b CDK inhibitor, glutathioneS-transferase (which detoxifies reactive oxygen species [ROS]), and the E-cadherin molecule (important for junction formation between epithelial cells). Epigenetic silencing can affect genes involved in DNA repair, thus predisposing to further genetic damage. Examples include MLH1 (mutL homologue in sporadic colon cancers that have micro­ satellite instability) and MSH2 in a subset of hereditary nonpolyposis colon cancer patients who have a mutation in the 3′ end of epithelial cell adhesion molecule (EPCAM). These are critical genes involved in No transcription Differentiation arrested Deregulated proliferation DNMT HDAC MeCP Nucleosomes Treatment: 5-aza-2'-deoxycytidine HDAC inhibitors Active transcription of tumor suppressor genes RNA polymerase II and general transcription machinery repair of mismatched bases that occur during DNA synthesis, and their silencing can lead to mutations in the DNA. Human leukemias often have chromosomal translocations that code for novel fusion proteins with activities that alter chromatin structure by interacting with HDACs or histone acetyl transferases (HATs). For example, the promyelocytic leukemia–retinoic acid receptor α (PML-RARα) fusion protein, generated by the t(15;17) translocation observed in most cases of acute promyelocytic leukemia (APL), binds to promoters containing retinoic acid response elements and recruits HDACs to these promoters, effectively inhibiting gene expression. This arrests differentiation at the promyelocyte stage and promotes tumor cell proliferation and survival. Treatment with pharmacologic doses of all-trans retinoic acid (ATRA), the ligand for RARα, results in the release of HDAC activity and the recruitment of coactivators, which overcome the differentiation block. This induced differentiation of APL cells has improved treatment of these patients but also has led to a novel treatment toxicity when newly differentiated tumor cells infiltrate the lungs. ATRA represents a treatment paradigm for the reversal of epigenetic changes in cancer. Other leukemia-associated fusion proteins, such as Tel-acute myeloid leukemia (AML1), AML1eight-twenty-one (ETO), and the MLL fusion proteins seen in acute myeloid leukemia (AML) and acute lymphocytic leukemia, also lead to repression through the HDAC complex. Therefore, efforts are ongoing to determine the structural basis for interactions between transloca­ tion fusion proteins and chromatin-remodeling proteins and to use this information to rationally design small molecules that will disrupt specific protein-protein associations, although this has proven to be technically difficult. Several drugs that block the enzymatic activity of HDACs (HDAC inhibitors [HDACis]) are approved for cancer treatment, and others are being tested. HDACis have demonstrated sufficient antitumor activity against cutaneous T-cell lymphoma (vori­ nostat, romidepsin), peripheral T-cell lymphoma (romidepsin, belino­ stat), and multiple myeloma (panobinostat) to be approved by the U.S. Food and Drug Administration (FDA). HDACis have also demonstrated antitumor activity in clinical stud­ ies against some solid tumors, and additional studies are ongoing. HDACis may target cancer cells via a number of mechanisms including both epigenetic modulation via histone acetylation and effects on other proteins that are acetylated. The pleiotropic effects of some HDACis include enhancement of apoptosis by upregulation of a number of pro­ teins that enhance apoptosis including death receptors (DR4/5, FAS, and their ligands) and downregulation of proteins that inhibit apopto­ sis (e.g., X-linked inhibitor of apoptosis [XIAP]); upregulation of pro­ teins that inhibit cell cycle progression (e.g., p21Cip1/Waf1); inhibition of DNA repair and generation of ROS leading to increased DNA dam­ age; and disruption of the chaperone protein HSP90. Efforts are also under way to modulate other epigenetic processes such as reversing the hypermethylation of CpG islands that characterizes many malignan­ cies. Drugs that induce DNA demethylation, such as 5-aza-2-deoxy­ cytidine, can lead to reexpression of silenced genes in cancer cells with restoration of function, and 5-aza-2-deoxycytidine is approved for use in myelodysplastic syndrome. However, 5-aza-2-deoxycytidine has limited aqueous solubility and is myelosuppressive, limiting its usefulness. Other inhibitors of DNA methyltransferases are in devel­ opment. In ongoing clinical trials, inhibitors of DNA methylation are being combined with HDACis, with the idea that reversing coexisting epigenetic changes will reverse the deregulated patterns of gene tran­ scription in cancer cells. Epigenetic gene regulation can also occur via microRNAs or long noncoding RNAs (lncRNA). MicroRNAs (miRNA) are short (average 22 nucleotides in length) single strand RNA molecules that regulate gene expression after transcription by specifically binding to and inhibiting the translation or promoting the degradation of mRNA transcripts. It is estimated that >1000 miRNAs are encoded in the human genome. Each tissue has a distinctive repertoire of miRNA expression, and this pattern is altered in specific ways in cancers. miRNA’s are involved in controlling multiple aspects of cell biology through modulating protein expression (primarily by down regula­ tion) and thus are also involved in multiple aspects of cancer biology. Specific correlations between expression of different miRNA molecules and tumor biology and clinical behavior are continuing to emerge. Therapies targeting miRNAs are not currently at hand but represent an ongoing area of treatment development. LncRNAs are longer than 200 nucleotides and comprise the largest group of noncoding RNAs. Some of them have been shown to play important roles in gene regulation. The potential for altering these RNAs for therapeutic benefit is an area of active investigation. In addition to epigenetic changes, mutations in genes (such as enhancer and promoter regions) involved in controlling expression of other genes important in cancer cell biology can also lead to enhanced or decreased expression of the protein products of these genes. APOPTOSIS AND OTHER MECHANISMS OF CELL DEATH Tissue homeostasis requires a balance between the death of aged, terminally differentiated cells or severely damaged cells and their renewal by proliferation of committed progenitors. Genetic damage to growth-regulating genes of stem cells could lead to catastrophic results for the host as a whole. Thus, in normal cells, the genetic events caus­ ing activation of oncogenes or loss of tumor suppressors, which would be predicted to lead to unregulated cell proliferation unless corrected, also usually activate signal transduction pathways that block aberrant cell proliferation. These pathways can lead to forms of programmed cell death including apoptosis or autophagy (degradation of proteins and organelles by lysosomal proteases) or irreversible growth arrest (senescence). A number of other regulated cell death processes have been identified, including: pyroptosis, a caspase-1-dependent process leading to cleavage of gasdermins with subsequent formation of pores in the plasma membrane; ferroptosis (iron and reactive oxygen species dependent); and necroptosis (caspase-independent regulated cell death involving breakdown of cellular components and cell rupture, leading to inflammation and damage to surrounding tissues), which also play roles in tissue homeostasis and cell death. However, the exact roles they play in the fate of cancer cells and tissues are still being elucidated. Much as a panoply of intra- and extracellular signals impinge upon the core cell cycle machinery to regulate cell division, so too these signals are transmitted to a core enzymatic machinery that regulates cell death and survival. Cancer cells have developed mechanisms that either inhibit these processes to prevent cell death or utilize them to enhance survival. CHAPTER 77 Cancer Cell Biology Apoptosis is a tightly regulated process induced by two main path­ ways (Fig. 77-5). The extrinsic pathway of apoptosis is activated by cross-linking members of the tumor necrosis factor (TNF) receptor superfamily, such as CD95 (Fas) and death receptors DR4 and DR5, by their ligands, Fas ligand or TRAIL (TNF-related apoptosis-inducing ligand), respectively. This induces the association of FADD (Fas- associated death domain) and procaspase-8 to death domain motifs of the receptors. Caspase-8 is activated and then cleaves and activates effector caspases-3 and -7, which then target cellular constituents (including caspase-activated DNase, cytoskeletal proteins, and a num­ ber of regulatory proteins), inducing the morphologic appearance characteristic of apoptosis, which pathologists term karyorrhexis (liter­ ally “nucleus bursting”). The intrinsic pathway of apoptosis is initiated by the release of cytochrome c and SMAC (second mitochondrial activator of cas­ pases) from the mitochondrial intermembrane space in response to a variety of noxious stimuli, including DNA damage, loss of adherence to the extracellular matrix (ECM), oncogene-induced proliferation, and growth factor deprivation. Upon release into the cytoplasm, cytochrome c associates with dATP, procaspase-9, and the adaptor protein APAF-1, leading to the sequential activation of caspase-9 and effector caspases. SMAC binds to and blocks the function of inhibitor of apoptosis proteins (IAP), negative regulators of caspase activation. The release of apoptosis-inducing proteins from the mitochondria is regulated by pro- and antiapoptotic members of the Bcl-2 family. Antiapoptotic members (e.g., Bcl-2, Bcl-XL, and Mcl-1) associate with the mitochondrial outer membrane via their carboxyl termini, expos­ ing to the cytoplasm a hydrophobic binding pocket composed of Bcl-2 Trail DR4 or DR5 FADD Caspase 8 Pro-caspase 9 Cyt c APAF-1 dATP SMAC IAP BH3-only proteins Intermembrane space Bak BcI2 Matrix Bax PART 4 Oncology and Hematology Outer membrane Mitochondrion FIGURE 77-5  Therapeutic strategies to overcome aberrant survival pathways in cancer cells. 1. The extrinsic pathway of apoptosis can be selectively induced in cancer cells by TRAIL (the ligand for death receptors 4 and 5) or by agonistic monoclonal antibodies. 2. Inhibition of antiapoptotic Bcl-2 family members with antisense oligonucleotides or inhibitors of the BH3-binding pocket will promote formation of Bak- or Bax-induced pores in the mitochondrial outer membrane. 3. Epigenetic silencing of APAF-1, caspase-8, and other proteins can be overcome using demethylating agents and inhibitors of histone deacetylases. 4. Inhibitor of apoptosis proteins (IAP) blocks activation of caspases; small-molecule inhibitors of IAP function (mimicking SMAC action) should lower the threshold for apoptosis. 5. Signal transduction pathways originating with activation of receptor tyrosine kinase receptors (RTKs) or cytokine receptors promote survival of cancer cells by a number of mechanisms. Inhibiting receptor function with monoclonal antibodies, such as trastuzumab or cetuximab, or inhibiting kinase activity with small-molecule inhibitors can block the pathway. 6. The Akt kinase phosphorylates many regulators of apoptosis to promote cell survival; inhibitors of Akt may render tumor cells more sensitive to apoptosis-inducing signals; however, the possibility of toxicity to normal cells may limit the therapeutic value of these agents. 7 and 8. Activation of the transcription factor NF-κB (composed of p65 and p50 subunits) occurs when its inhibitor, IκB, is phosphorylated by IκB-kinase (IKK), with subsequent degradation of IκB by the proteasome. Inhibition of IKK activity should selectively block the activation of NF-κB target genes, many of which promote cell survival. Inhibitors of proteasome function are U.S. Food and Drug Administration approved and may work in part by preventing destruction of IκB, thus blocking NF-κB nuclear localization. NF-κB is unlikely to be the only target for proteasome inhibitors. homology (BH) domains 1, 2, and 3 that is crucial for their activity. Perturbations of normal physiologic processes in specific cellular compartments lead to the activation of BH3-only proapoptotic family members (e.g., Bad, Bim, Bid, Puma, Noxa, and others) that can alter the conformation of the outer-membrane proteins Bax and Bak, which then oligomerize to form pores in the mitochondrial outer membrane resulting in cytochrome c release. If proteins composed only by BH3 domains are sequestered by Bcl-2, Bcl-XL, or Mcl-1, pores do not form and apoptosis-inducing proteins are not released from the mito­ chondria. The ratio of levels of antiapoptotic Bcl-2 family members and the levels of proapoptotic BH3-only proteins at the mitochondrial membrane determines the activation state of the intrinsic pathway. The mitochondrion must therefore be recognized not only as an organelle with vital roles in intermediary metabolism and oxidative phosphory­ lation but also as a central regulatory structure of the apoptotic process. The evolution of tumor cells to a more malignant phenotype requires the acquisition of genetic changes that subvert apoptosis pathways and promote cancer cell survival and resistance to anticancer therapies. GF RTK PI3K Mdm2 AKT Cytokine receptor Effector caspases BAD Caspase FKHR Substrate cleavage IKK IκB p65 p50 Cytoskeletal disruption Proteasome NF-κB genes activated DNA degradation Chromatin condensation Lamin cleavage Nucleus Death-inducing signals • DNA damage • Oncogene-induced proliferation • Loss of attachment to ECM • Chemotherapy, radiation therapy However, this means that cancer cells may be more vulnerable than normal cells to therapeutic interventions that target the apoptosis pathways that cancer cells depend upon. For instance, overexpression of Bcl-2 as a result of the t(14;18) translocation contributes to follicular lymphoma, and it is highly expressed in many lymphoid malignancies including chronic lymphocytic leukemia (CLL). Upregulation of Bcl-2 expression is also observed in other cancers including prostate, breast and lung cancers, and melanoma. Targeting of antiapoptotic Bcl-2 family members has been accomplished by the identification of several low-molecular-weight compounds that bind to the hydrophobic pock­ ets of either Bcl-2 or Bcl-XL and block their ability to associate with death-inducing BH3-only proteins. An oral BH3 mimetic inhibitor of BCL-2, venetoclax, is approved for use in patients with refractory CLL with 17p deletion, and is active in AML. Preclinical studies targeting death receptors DR4 and -5 have demonstrated that recombinant, soluble, human TRAIL or humanized monoclonal antibodies with agonist activity against DR4 or -5 can induce apoptosis of tumor cells while sparing normal cells. The mechanisms for this selectivity may include expression of decoy receptors or elevated levels of intracellular inhibitors (such as FLIP, which competes with caspase-8 for FADD) by normal cells but not tumor cells. Synergy has been shown between TRAIL-induced apoptosis and chemotherapeutic agents in some pre­ clinical studies. However, studies have not yet shown significant clini­ cal activity of approaches targeting the TRAIL pathway. Many of the signal transduction pathways perturbed in cancer pro­ mote tumor cell survival (Fig. 77-5). These include activation of the PI3K/Akt pathway, increased levels of the NF-κB transcription factor, and epigenetic silencing of genes such as APAF-1 (apoptosis protease activating factor-1 involved in activating caspase-9 and essential for apoptosis) and caspase-8. Each of these pathways is a target for thera­ peutic agents that, in addition to affecting cancer cell proliferation or gene expression, may render cancer cells more susceptible to apoptosis, thus promoting synergy when combined with other chemotherapeutic agents. Some tumor cells resist drug-induced apoptosis indirectly by elimi­ nating the noxious stimulus-inducing apoptosis through expression of one or more members of the ABC (ATP-binding cassette proteins) family of ATP-dependent efflux pumps that mediate the multidrug resistance (MDR) phenotype. The prototype member of this family, P-glycoprotein (PGP), spans the plasma membrane 12 times and has two ATP-binding sites. Hydrophobic drugs (e.g., anthracyclines and vinca alkaloids) are recognized by PGP as they enter the cell and are pumped out. Numerous clinical studies have failed to demonstrate that drug resistance can be overcome using inhibitors of PGP. However, ABC transporters have different substrate specificities, and inhibition of a single family member may not be sufficient to overcome the MDR phenotype. Efforts to reverse PGP-mediated drug resistance continue. In addition to its role in cell death, autophagy can also serve as a homeostatic mechanism to promote cell survival by recycling cellular components to provide necessary energy. The mechanisms that control the balance between enhancing survival versus leading to cell death are still not fully understood. Autophagy appears to play conflicting roles in the development and survival of cancer. Early in the carcinogenic process, it can act as a tumor suppressor by preventing the cell from accumulating abnormal proteins and organelles. However, in estab­ lished tumors, it may serve as a mechanism of survival for cancer cells when they are stressed by damage such as from chemotherapy. Preclin­ ical studies have indicated that inhibition of this process can enhance the sensitivity of cancer cells to chemotherapy or radiation therapy, and ongoing trials are evaluating inhibitors of autophagy in combination with chemotherapy and/or radiation therapy. Better understanding of the factors that control the survival-promoting versus death-inducing aspects of autophagy is required in order to know how to best manipu­ late it for therapeutic benefit. ■ ■METASTASIS The metastatic process accounts for the vast majority of deaths from solid tumors, and therefore, an understanding of this process is critical for improvements in survival from cancer. The biology of metastasis is complex and requires multiple steps. The initial step involves cell migration and invasion through the ECM. The three major features of tissue invasion are cell adhesion to the basement membrane, local proteolysis of the membrane, and movement of the cell through the rent in the membrane and the ECM. Cells that lose contact with the ECM normally undergo programmed cell death (anoikis-apoptosis induced by the loss of contact), and this process has to be suppressed in cells that metastasize. Another process important for many, but not necessarily all, metastasizing epithelial cancer cells is epithelial mes­ enchymal transition (EMT). This is a process by which cells lose their epithelial properties and gain mesenchymal properties. This normally occurs during the developmental process in embryos, allowing cells to migrate to their appropriate destinations in the embryo. It also occurs in wound healing, tissue regeneration, and fibrotic reactions, but in all of these processes, cells stop proliferating when the process is complete. Malignant cells that metastasize often undergo EMT as an important step in that process but retain the capacity for unregulated prolifera­ tion. However, there is evidence that not all metastasizing cancer cells require EMT, and the exact role of EMT in different metastasizing cancer cells continues to be elucidated. Malignant cells that gain access to the circulation must then repeat those steps at a remote site, find a hospitable niche in a foreign tissue, avoid detection and elimination by host defenses including the immune system, and induce the growth of new blood vessels. Some metastatic cells occur as oligoclonal clusters, which appear to be more potent in establishing metastasis than single cells, perhaps, in part, through differential and cooperative effects in evading host defenses. The rate-limiting step for metastasis is the ability for tumor cells to survive and expand in the novel microenvi­ ronment of the metastatic site, and multiple host-tumor interactions determine the ultimate outcome (Fig. 77-6). As is true for cells in primary cancers, there is significant hetero­ geneity as well as plasticity in metastatic cancer cells. In addition to actively dividing cells, a population of quiescent cells are present that can evade the immune system as well as chemotherapy targeting divid­ ing cells. The processes that keep metastatic cancer cells quiescent as well as lead them to divide are complex, as discussed in the introduc­ tory section. Efforts to inhibit growth of metastatic cells by modulating these pathways are being explored. Few drugs have been developed to attempt to directly target the process of metastasis, in part because the specifics of the critical steps in the process that would be potentially good targets for drugs are still being identified. However, a number of potential targets are known. HER2 can enhance the metastatic potential of breast cancer cells, and as discussed above, the monoclonal antibody trastuzumab, which targets HER2, improves survival in the adjuvant setting for HER2-positive breast cancer patients. A number of other potential targets that increase metastatic potential of cells in preclinical studies include HIF-1 and -2, transcription factors induced by hypoxia within tumors, growth factors (e.g., cMET and VEGFR), oncogenes (e.g., SRC), adhesion molecules (e.g., focal adhesion kinase [FAK]), ECM proteins (e.g., matrix metalloproteinases 1 and 2), and inflammatory molecules (e.g., COX-2). CHAPTER 77 Cancer Cell Biology The metastatic phenotype is likely restricted to a fraction of tumor cells (Fig. 77-6). A number of genetic and epigenetic changes are required for tumor cells to be able to metastasize, including activation of metastatic-promoting genes and inhibition of genes that suppress the metastatic ability. Given the role of microRNAs in controlling gene expression (see epigenetic section) including those critical to the meta­ static process, efforts are under way to modulate these to try to inhibit metastasis. Cells with metastatic capability frequently express chemo­ kine receptors that are likely important in the metastatic process. A number of candidate metastasis-suppressor genes have been identified, including genes coding for proteins that enhance apoptosis, suppress cell division, are involved in the interactions of cells with each other or the ECM, or suppress cell migration. The loss of function of these genes enhances metastasis. Gene expression profiling is being used to study the metastatic process and other properties of tumor cells that may predict susceptibilities. An example of the ability of malignant cells to survive and grow in a novel microenvironment is bone metastases. Bone metastases can be extremely painful, cause fractures of weight-bearing bones, can lead to hypercalcemia, and are a major cause of morbidity for cancer patients. Osteoclasts and their monocyte-derived precursors express the sur­ face receptor RANK (receptor activator of NF-κB), which is required for terminal differentiation and activation of osteoclasts. Osteoblasts and other stromal cells express RANK ligand (RANKL), as both a membrane-bound and soluble cytokine. Osteoprotegerin (OPG), a soluble receptor for RANKL produced by stromal cells, acts as a decoy receptor to inhibit RANK activation. The relative balance of RANKL and OPG determines the activation state of RANK on osteoclasts. Bone modulation and resorption by osteoclasts is an important component of the establishment and progression of metastases in bone. Many tumors increase osteoclast activity by secretion of substances such as parathyroid hormone (PTH), PTH-related peptide, interleukin (IL) 1, or Mip1 that perturb the homeostatic balance of bone remodeling by increasing RANK signaling. One example is multiple myeloma, where tumor cell–stromal cell interactions activate osteoclasts and inhibit osteoblasts, leading to the development of multiple lytic bone lesions. Basement membrane Normal epithelial cells Cytokeratin Adherens junction E-cadherin Tumor cell TGF-β receptor TGF-β N-Cadherin Snail Twist HGF New integrin expression N-Cadherin C-Met PART 4 Oncology and Hematology FIGURE 77-6  Oncogene signaling pathways are activated during tumor progression and promote metastatic potential. This figure shows a cancer cell that has undergone epithelial to mesenchymal transition (EMT) under the influence of several environmental signals. Critical components include activated transforming growth factor beta (TGF-β) and the hepatocyte growth factor (HGF)/c-Met pathways, as well as changes in the expression of adhesion molecules that mediate cell-cell and cell–extracellular matrix interactions. Important changes in gene expression are mediated by the Snail and Twist family of transcriptional repressors (whose expression is induced by the oncogenic pathways), leading to reduced expression of E-cadherin, a key component of adherens junctions between epithelial cells. This, in conjunction with upregulation of N-cadherin, a change in the pattern of expression of integrins (which mediate cell–extracellular matrix associations that are important for cell motility), and a switch in intermediate filament expression from cytokeratin to vimentin, results in the phenotypic change from adherent highly organized epithelial cells to motile and invasive cells with a fibroblast or mesenchymal morphology. EMT is thought to be an important step leading to metastasis in some human cancers. Host stromal cells, including tumorassociated fibroblasts and macrophages, play an important role in modulating tumor cell behavior through secretion of growth factors and proangiogenic cytokines, and matrix metalloproteinases that degrade the basement membrane. VEGF-A, -C, and -D are produced by tumor cells and stromal cells in response to hypoxemia or oncogenic signals and induce production of new blood vessels and lymphatic channels through which tumor cells metastasize to lymph nodes or tissues. Inhibition of RANKL by an antibody (denosumab) can prevent fur­ ther bone destruction. Bisphosphonates are also effective inhibitors of osteoclast function that are used in the treatment of cancer patients with bone metastases. ■ ■CANCER STEM CELLS Normal tissues have stem cells capable of self-renewal and repairing damaged tissue, whereas the majority of cells in normal tissues do not have this capacity. Similarly, only a small proportion of the cells within a tumor are capable of initiating colonies in vitro or forming tumors at high efficiency when injected into immunocompromised NOD/ SCID mice. For example, AML and CML have a small population of cells (estimated to be <1%) that have properties of stem cells, such as unlimited self-renewal and the capacity to cause leukemia when serially transplanted in mice. These cells have an undifferentiated phenotype (Thy1–CD34+CD38– and do not express other differentia­ tion markers) and resemble normal stem cells in many ways but are no longer under homeostatic control (Fig. 77-7). Solid tumors may also contain a population of stem cells. It is not yet known how often cancers may originate within a stem cell population, although a body of evidence argues that stem cells are likely involved in the develop­ ment of the majority of cancers. Cancer stem cells, like their normal counterparts, have unlimited proliferative capacity and paradoxically traverse the cell cycle at a slow rate; cancer growth occurs largely due to expansion of the stem cell pool, the unregulated proliferation of an Lamina propria Tumor-associated fibroblast New lymph vessel MMP Cytokines growth factors Tumor-associated macrophage Invasion New blood vessel VEGF-A HOST STROMAL CELLS amplifying population, and failure of apoptosis pathways (Fig. 77-7). Slow cell cycle progression and high levels of expression of antiapop­ totic Bcl-2 family members and drug efflux pumps of the MDR family render cancer stem cells less vulnerable to cancer chemotherapy or radiation therapy. Implicit in the cancer stem cell hypothesis is the idea that failure to cure most human cancers is due to the fact that current therapeutic agents are not very effective in killing stem cells. Efforts are ongoing to identify and isolate cancer stem cells from different types of malig­ nancies, which should allow determination of the aberrant signaling pathways that distinguish these cells from normal tissue stem cells. These would serve as potential therapeutic targets. Evidence that cells with stem cell properties can arise from other epithelial cells within the cancer by processes such as epithelial mesenchymal transition also implies that it is essential to treat all of the cancer cells, and not just those with current stem cell–like properties, in order to eliminate the self-renewing cancer cell population. The exact nature of cancer stem cells remains an area of investigation. One of the unanswered questions is the exact origin of cancer stem cells for the different cancers. PLASTICITY AND RESISTANCE Cancer cells, and especially stem cells, have the capacity for significant plasticity, allowing them to alter multiple aspects of cell biology in response to external factors (e.g., chemotherapy, radiation therapy, inflammation, immune response). In addition, heterogeneity between NORMAL TISSUE CANCER Stem Cells Stem cell niche Paracrine signals Polarized division Daughter cell Stem cell Transit-amplifying cells Exponential growth Regulated activation of differentiation program Loss of self-renewal capacity Multilineage differentiation Growth arrest Maintenance of tissue architecture and homeostasis FIGURE 77-7  Cancer stem cells play a critical role in the initiation, progression, and resistance to therapy of malignant neoplasms. In normal tissues (left), homeostasis is maintained by asymmetric division of stem cells, leading to one progeny cell that will differentiate and one cell that will maintain the stem cell pool. This occurs within highly specific niches unique to each tissue, such as in close apposition to osteoblasts in bone marrow, or at the base of crypts in the colon. Here, paracrine signals from stromal cells, such as sonic hedgehog or Notch ligands, as well as upregulation of β-catenin and telomerase, help to maintain stem cell features of unlimited self-renewal while preventing differentiation or cell death. This occurs in part through upregulation of the transcriptional repressor Bmi-1 and inhibition of the p16Ink4a/Arf and p53 pathways. Daughter cells leave the stem cell niche and enter a proliferative phase (referred to as transit-amplifying) for a specified number of cell divisions, during which time a developmental program is activated, eventually giving rise to fully differentiated cells that have lost proliferative potential. Cell renewal equals cell death, and homeostasis is maintained. In this hierarchical system, only stem cells are long-lived. The hypothesis is that cancers harbor stem cells that make up a small fraction (i.e., 0.001–1%) of all cancer cells. These cells share several features with normal stem cells, including an undifferentiated phenotype, unlimited self-renewal potential, and a capacity for some degree of differentiation; however, due to initiating mutations (mutations are indicated by lightning bolts), they are no longer regulated by environmental cues. The cancer stem cell pool is expanded, and rapidly proliferating progeny, through additional mutations, may attain stem cell properties, although most of this population is thought to have a limited proliferative capacity. Differentiation programs are dysfunctional due to reprogramming of the pattern of gene transcription by oncogenic signaling pathways. Within the cancer transit-amplifying population, genomic instability generates aneuploidy and clonal heterogeneity as cells attain a fully malignant phenotype with metastatic potential. The cancer stem cell hypothesis has led to the idea that current cancer therapies may be effective at killing the bulk of tumor cells but do not kill tumor stem cells, leading to a regrowth of tumors that is manifested as tumor recurrence or disease progression. Research is in progress to identify unique molecular features of cancer stem cells that can lead to their direct targeting by novel therapeutic agents. the different clones of cells within the tumor population and their interactions with each other and the tumor microenvironment pro­ vides the tumor with the capacity for significant plasticity in dealing with both internal and external stresses. Thus, a major problem in can­ cer therapy is that malignancies have a wide spectrum of mechanisms for both initial and adaptive resistance to treatments. These include inhibiting drug delivery to the cancer cells, blocking drug uptake and retention, increasing drug metabolism, altering levels of target proteins making them less sensitive to drugs, acquiring mutations in target proteins making them no longer sensitive to the drug, modify­ ing metabolism and cell signaling pathways, using alternate signaling pathways, adjusting the cell replication process including mechanisms by which the cell deals with DNA damage, inhibiting apoptosis, and evading the immune system. Thus, most metastatic cancers (except those curable with chemotherapy such as germ cell tumors) eventually become resistant to the therapy being utilized. Overcoming resistance is a major area of research. ■ ■CANCER METABOLISM One of the distinguishing characteristics of cancer cells is that they have altered metabolism as compared with normal cells in supporting sur­ vival, their high rates of proliferation, and ability to metastasize. Com­ plicating studies evaluating metabolic differences between normal and malignant cells is that there is heterogeneity in metabolism between different cells within a cancer. Malignant cells must focus a significant fraction of their energy resources into synthesis of proteins and other molecules (building blocks required for the production of new cells) while still maintaining sufficient ATP production to survive and grow. Differentiation Cancer Stem Cells Altered or expanded stem cell niche Initiating mutations Transit-amplifying cells Exponential growth Altered transcription program Differentiation arrest Genetic instability Secondary mutations Limited self-renewal capacity Partial differentiation No growth arrest CHAPTER 77 Loss of tissue architecture and homeostasis control Cancer Cell Biology Although normal proliferating cells also have similar needs, there are differences in how cancer cells metabolize glucose and a number of other compounds including the amino acid glutamine as compared to normal cells in part because of genetic and epigenetic changes within cancer cells but also likely due to differences in the environments of cancer and normal cells. Many cancer cells utilize aerobic glycolysis (the Warburg effect) (Fig. 77-8) to metabolize glucose, leading to increased lactic acid production, whereas normal cells utilize oxidative phosphorylation in mitochondria under aerobic conditions, a much more efficient process for generating ATP for energy utilization but one that does not produce the same level of building blocks needed for new cells. One consequence is increased glucose uptake and utilization by cancer cells, a fact utilized in fluorodeoxyglucose (FDG)-positron emission tomography (PET) scanning to detect tumors. A number of proteins in cancer cells, including cMYC, HIF1, RAS, p53, pRB, and AKT, are involved in modulating glycolytic processes and controlling the Warburg effect. Although these pathways overall remain difficult to target therapeutically, some progress has been made in targeting HIF1 and the RAS pathways with inhibitors approved to treat cancers with mutations in HIF1α or KRAS12C. In addition, both the PI3K pathway with signaling through mTOR and the AMP-activated kinase (AMPK) pathway that inhibits mTORC1 (a protein complex that includes mTOR) are important in controlling the glycolytic process and thus provide potential targets for inhibiting this process. An inhibitor of mTOR is approved for use against RCC (temsirolimus), and another inhibitor (everolimus) has activity against breast and neuroendocrine cancer and RCC. Other mTOR inhibitors are in trials, and modulators of AMPK are being investigated. The inefficient utilization of glucose Differentiated tissue Tumor Proliferative tissue or +O2 –O2 +/–O2 Glucose Glucose Glucose Pyruvate Pyruvate Pyruvate O2 O2 Lactate Lactate Lactate CO2 Anaerobic glycolysis 2 mol ATP/ mol glucose Oxidative phosphorylation –36 mol ATP/ mol glucose FIGURE 77-8  Warburg versus oxidative phosphorylation. In most normal tissues, the vast majority of cells are differentiated and dedicated to a particular function within the organ in which they reside. The metabolic needs are mainly for energy and not for building blocks for new cells. In these tissues, ATP is generated by oxidative phosphorylation that efficiently generates about 36 molecules of ATP for each molecule of glucose metabolized. By contrast, proliferative tumor tissues, especially in the setting of hypoxia, a typical condition within tumors, use aerobic glycolysis to generate energy for cell survival and generation of building blocks for new cells. PART 4 Oncology and Hematology by malignant cells also leads to a need for alternative metabolic path­ ways for other compounds as well, one of which is glutamine. Similar to glucose, this provides both a source for structural molecules as well as energy production. Similarly to glucose, glutamine is also ineffi­ ciently utilized by cancer cells. Cancer cells can also take up nutrients released by surrounding cells and tissues, increasing the complexity of successfully therapeutically inhibiting metabolism in cancer. Mutations in genes involved in the metabolic process occur in a number of cancers. Among the most frequently found to date are muta­ tions in isocitrate dehydrogenases 1 and 2 (IDH1 and IDH2). These have been most commonly seen in gliomas, AMLs, and intrahepatic cholangiocarcinomas. These mutations lead to the production of an oncometabolite (2-hydroxyglutarate [2HG]) instead of the normal product α-ketoglutarate. Although the exact mechanisms of oncogen­ esis by 2HG are still being elucidated, α-ketoglutarate is a key cofactor for a number of dioxygenases involved in controlling DNA methyla­ tion. 2HG can act as a competitive inhibitor for α-ketoglutarate, lead­ ing to alterations in methylation status (primarily hypermethylation) of genes (leading to epigenetic changes) that can have profound effects on a number of cellular processes including differentiation. Inhibitors of mutant IDH1 and/or IDH2 are approved for treating IDH mutant AML and cholangiocarcinoma; and a dual IDH1/2 inhibitor is approved for treatment of low-grade gliomas and astrocytomas with IDH mutations. Much needs to be learned about the specific differences in metabo­ lism between cancer cells and normal cells in order to develop more effective approaches to using these differences therapeutically; how­ ever, even with the currently limited state of knowledge, modulators of metabolism are being tested clinically. One of these is the antidiabetic agent metformin, both alone and in combination with chemotherapeu­ tic agents. Metformin inhibits gluconeogenesis and may have direct effects on tumor cells by activating AMPK, a serine/threonine protein kinase that is downstream of the LKB1 tumor suppressor, and thus inhibiting mTOR complex 1 (mTORC1). This leads to decreased pro­ tein synthesis and proliferation. Studies to date have not yet established metformin to have a clear role as an anticancer agent. ■ ■TUMOR MICROENVIRONMENT, ANGIOGENESIS, AND IMMUNE EVASION Tumors consist not only of malignant cells but also of a complex microenvironment including many other types of cells (including lymphocytes, macrophages, myeloid cells; other inflammatory cells; 5% 85% CO2 Aerobic glycolysis (Warburg effect) –4 mol ATP/mol glucose vascular cells, lymphatic endothelial cells, nerve cells, fibroblasts, and fat cells), ECM, stroma, secreted factors (including growth factors and hormones), reactive oxygen and nitrogen species, mechanical factors, blood vessels, and lymphatics. There is extensive cross-talk between the cells with each other, the ECM, and the various secreted factors within the tumor microenvironment. This microenvironment is not static but rather is dynamic and continually evolving. Both the complexity and dynamic nature of the microenvironment enhance the difficulty of treating tumors. The microenvironment is involved in altered tumor metabolism, tumor maintenance, growth, phenotypic plasticity, metas­ tasis, and immune escape, and can contribute to resistance to antican­ cer therapies through a number of mechanisms. These include immune evasion by a variety of mechanisms including suppression of effector T cells, increase in regulatory T cells, induction of an inflammatory environment, and altered vasculature that inhibits effector T-cell access to malignant cells. Similarly, it contributes to drug resistance through multiple mechanisms, alteration in metabolic pathways including creating a hypoxic and acidic environment, vascular and mechanical factors that limit drug access to malignant cells, various secreted factors that inhibit apoptosis or stimulate survival pathways, and generation of ROS that enhance drug resistance. Multiple additional mechanisms are also involved in enhancing resistance to immune-mediated anticancer effects and anticancer drug therapy. ■ ■OBESITY AND CANCER Significant evidence links obesity and the increased risk of devel­ oping certain cancers including postmenopausal breast, colorectal, ovarian, endometrial, esophageal, gallbladder, thyroid, and kidney cancers, among others. Less certain are the mechanisms responsible for this risk. As outlined above, cancers arise in an environment with multiple factors, many of which can stimulate cell proliferation. Obe­ sity impacts a variety of factors including hormonal factors, altered metabolism (especially adipose metabolism), and mediators of inflam­ matory response that all can impact the development of malignancy. Obesity is associated with a number of hormonal changes including high insulin, glucagon, and leptin levels that can stimulate growth of cells. It also leads to insulin resistance, which may contribute to cancer cell development, in part by increasing insulin-like growth factor-1 (IGF-1) levels. Obesity also leads to alterations in adipose, including fatty acid, metabolism with production of compounds important for energy metabolism as well as for membrane function within cells that may contribute to carcinogenic process. Obesity contributes to an inflammatory environment in a variety of ways including increased levels of inflammatory proteins such as IL-6 and TNF-α. In terms of impact on survival with cancer, data primarily from breast cancer suggest that obesity is associated with decreased survival likely due, at least in part, to the impact of obesity on hormonal factors in development of certain breast cancers, although this may be limited to subsets of breast cancer patients. Some studies have suggested, para­ doxically, that obesity may be associated with improved survival in some patients such as those with advanced-stage colorectal cancer. Further­ more, immune checkpoint inhibitor therapy has appeared to be more effect in obese patients. Clearly, the biology of the association between obe­ sity and cancer and its impact on disease outcome is complex, and additional studies are necessary to better define the mechanisms involved. Vascular mimicry— tumor cells as part of vessel wall Tumor ■ ■MECHANISMS OF TUMOR VESSEL FORMATION One of the critical elements of tumor cell pro­ liferation is delivery of oxygen, nutrients, and circulating factors important for growth and sur­ vival. Thus, a critical element in growth of pri­ mary tumors and formation of metastatic sites is the angiogenic switch: the ability of the tumor to promote the formation of new blood vessels, including the recruitment of vascular endothelial cells (ECs). The angiogenic switch is a phase in tumor development when the dynamic balance of pro- and antiangiogenic factors is tipped in favor of vessel formation by the effects of the tumor on its immediate environment. Stimuli for tumor angio­ genesis include hypoxemia, inflammation, and genetic lesions in oncogenes or tumor suppressors that alter tumor cell gene expression. Angiogenesis consists of several steps, including the stimula­ tion of ECs by growth factors, degradation of the ECM by proteases, proliferation and migration of ECs into the tumor, and the eventual formation of new capillary tubes. Tumors use a number of mechanisms to promote vascularization, subvert­ ing normal angiogenic processes for this purpose (Fig. 77-9). Primary or metastatic tumor cells sometimes arise in proximity to host blood vessels and grow around these vessels, parasitizing nutri­ ents by co-opting the local blood supply. However, most tumor blood vessels arise by the process of sprouting, in which tumors secrete trophic angio­ genic molecules, the most potent being vascular endothelial growth factors (VEGFs), that induce the proliferation and migration of host ECs into the tumor. Sprouting in normal and patho­ genic angiogenesis is regulated by three families of transmembrane RTKs expressed on ECs and their ligands (VEGFs, angiopoietins, and ephrins; Fig. 77-10), which are produced by tumor cells, inflammatory cells, or stromal cells in the tumor microenvironment. FIGURE 77-9  Tumor angiogenesis is a complex process involving many different cell types that must proliferate, migrate, invade, and differentiate in response to signals from the tumor microenvironment. Endothelial cells (ECs) sprout from host vessels in response to VEGF, bFGF, Ang2, and other proangiogenic stimuli. Sprouting is stimulated by VEGF/VEGFR2, Ang2/Tie-2, and integrin/extracellular matrix (ECM) interactions. Bone marrow–derived circulating endothelial precursors (CEPs) migrate to the tumor in response to VEGF and differentiate into ECs, while hematopoietic stem cells differentiate into leukocytes, including tumor-associated macrophages that secrete angiogenic growth factors and produce matrix metalloproteinases (MMPs) that remodel the ECM and release bound growth factors. Tumor cells themselves may directly form parts of vascular channels within tumors. The pattern of vessel formation is haphazard: vessels are tortuous, dilated, leaky, and branch in random ways. This leads to uneven blood flow within the tumor, with areas of acidosis and hypoxemia (which stimulate release of angiogenic factors) and high intratumoral pressures that inhibit delivery of therapeutic agents. Central to the angiogenic response are hypoxia-inducible factors (HIFs; especially 1 and 2), which are transcription factors that normally, in response to hypoxia, stimulate the transcription of a large number of genes responsive to hypoxia, including genes involved in metabolism as well as angiogenesis. HIF1 has a bigger role in stimulating metabolism (glycogenesis), whereas HIF2 plays a bigger role in angiogenesis. HIF protein function can also be enhanced in a number of ways in cancer not involving hypoxia, including mutations in the von Hippel–Lindau tumor suppressor gene (an E3 ubiquitin ligase that controls HIF levels by targeting it for degradation), such as occurs in some RCCs. Among CEP contributes newly differentiated EC HSC-derived macrophage Tumor Leaky vessels Tumor Region of hypoxemia 100 µm High intratumoral pressure Dilated leaky tumor vessel VEGF VEGF VEGFR2 VEGFR2 Destabilization Tie 2 Tie 2 Ang2 ανβ 2 ανβ 3 ανβ 5 α5β 1 α5β 1 ECM Tie 2 New sprout Follows VEGF gradient to tumor CHAPTER 77 Migrate to tumor Host blood vessel VEGFR2 CEP CD133 Cancer Cell Biology Bone marrow–derived cells (from hemangioblast) VEGFR1 HSC c-kit Tumor cells Host EC Tumor EC Circulating endothelial precursors (CEP) Hematopoietic cell–derived leukocytes (HSC) the genes stimulated by HIF are VEGF and VEGF receptors. VEGFs and their receptors are required for embryonic vasculogenesis (devel­ opment of new blood vessels when none preexist) and normal (wound healing, corpus luteum formation) and pathologic angiogenesis (tumor angiogenesis, inflammatory conditions such as rheumatoid arthritis). VEGF-A is a heparin-binding glycoprotein with at least four isoforms (splice variants) that regulates blood vessel formation by binding to the RTKs VEGFR1 and VEGFR2, which are expressed on all ECs in addition to a subset of hematopoietic cells (Fig. 77-9). VEGFR2 plays a more direct role in regulating EC proliferation, migration, and survival, whereas VEGFR1 appears to have more nuanced functions with a less direct role in stimulating EC processes in the normal adult (even act­ ing as a decoy protein for VEGFA to decrease binding to VEGFR2) but with important effects during embryogenesis and on tumor angiogen­ esis. Tumor vessels may be more dependent on VEGFR signaling for growth and survival than normal ECs. Endothelial cell–“specific” ligand/receptor complexes PIGF VEGF-A VEGF-B VEGF-C Ang-1 Ang-2 Ephrins Extracellular matrix bFGF PDGF Kinase domain αvβ3 Matrix (attachment) EPHB4 (Arteryvein differentiation, vessel remodeling) VEGFR1 VEGFR2 VEGFR3 (Endothelial cells) (Lymphatics) Tie-2 (Blood vessel stabilization and remodeling) Downstream pathways Ras/MAPK Pl3K/AKT Rho/Rac/cdc42 NFκB PART 4 Oncology and Hematology Endothelial cell proliferation, migration, survival FIGURE 77-10  Critical molecular determinants of endothelial cell biology. Angiogenic endothelium expresses a number of receptors not found on resting endothelium. These include receptor tyrosine kinases (RTKs) and integrins that bind to the extracellular matrix and mediate endothelial cell (EC) adhesion, migration, and invasion. ECs also express RTKs (i.e., the fibroblast growth factor [FGF] and platelet-derived growth factor [PDGF] receptors) that are found on many other cell types. Critical functions mediated by activated RTK include proliferation, migration, and enhanced survival of endothelial cells, as well as regulation of the recruitment of perivascular cells and bloodborne circulating endothelial precursors and hematopoietic stem cells to the tumor. Intracellular signaling via EC-specific RTK utilizes molecular pathways that may be targets for future antiangiogenic therapies. While VEGF signaling is a critical initiator of angiogenesis, this is a complex process regulated by additional signaling pathways (Fig. 77-10). The angiopoietin, Ang1, produced by stromal cells, binds to the EC RTK Tie-2 and promotes the interaction of ECs with the ECM and perivascular cells, such as pericytes and smooth-muscle cells, to form tight, nonleaky vessels. PDGF and basic fibroblast growth fac­ tor (bFGF) help to recruit these perivascular cells. Ang1 is required for maintaining the quiescence and stability of mature blood vessels and prevents the vascular permeability normally induced by VEGF and inflammatory cytokines. For tumor cell–derived VEGF to initiate sprouting from host vessels, the stability conferred by the Ang1/Tie2 pathway must be perturbed; this occurs by the secretion of Ang2 by ECs that are undergoing active remodeling. Ang2 binds to Tie2 and is a competitive inhibitor of Ang1 action: under the influence of Ang2, preexisting blood vessels become more responsive to remodeling sig­ nals, with less adherence of ECs to stroma and associated perivascular cells and more responsiveness to VEGF. Therefore, Ang2 is required at early stages of tumor angiogenesis for destabilizing the vasculature by making host ECs more sensitive to angiogenic signals. In the presence of Ang2, there is no stabilization by the Ang1/Tie2 interaction, and tumor blood vessels are leaky, hemorrhagic, and have poor association of ECs with underlying stroma. Sprouting tumor ECs express high levels of the transmembrane protein ephrin-B2 and its receptor, the RTK EPH, whose signaling appears to work with the angiopoietins during vessel remodeling. During embryogenesis, EPH receptors are expressed on the endothelium of primordial venous vessels while the transmembrane ligand ephrin-B2 is expressed by cells of primordial arteries; the reciprocal expression may regulate differentiation and pat­ terning of the vasculature. A number of additional ubiquitously expressed host molecules play critical roles in normal and pathologic angiogenesis. Proangiogenic cytokines, chemokines, and growth factors secreted by stromal cells or inflammatory cells make important contributions to neo­ vascularization, including bFGF, transform­ ing growth factor-β (TGF-β), TNF-α, and IL-8. In contrast to normal endothelium, angiogenic endothelium overexpresses spe­ cific members of the integrin family of ECMbinding proteins that mediate EC adhesion, migration, and survival. Specifically, expres­ sion of integrins αvβ3, αvβ5, and α5β1 mediates spreading and migration of ECs and is required for angiogenesis induced by VEGF and bFGF, which in turn can upregulate EC integrin expression. The αvβ3 integrin physi­ cally associates with VEGFR2 in the plasma membrane and promotes signal transduction from each receptor to promote EC prolifera­ tion (via focal adhesion kinase, src, PI3K, and other pathways) and survival (by inhibition of p53 and increasing the Bcl-2/Bax expression ratio). In addition, αvβ3 forms cell-surface complexes with matrix metalloproteinases (MMPs), zinc-requiring proteases that cleave ECM proteins, leading to enhanced EC migration and the release of heparin-binding growth factors, including VEGF and bFGF. EC adhesion molecules can be upregulated (i.e., by VEGF, TNF-α) or downregulated (by TGF-β); this, together with chaotic blood flow, explains poor leukocyte-endothelial interactions in tumor blood vessels and may help tumor cells avoid immune surveillance. Generalized growth factor receptors FGF receptor PDGF receptor (Recruitment of smoothmuscle cells and pericytes) Tumor blood vessels are not normal; they have chaotic architecture and blood flow. Due to an imbalance of angiogenic regulators such as VEGFs and angiopoietins (see below), tumor vessels are tortuous and dilated with an uneven diameter, excessive branching, and shunting. Tumor blood flow is variable, with areas of hypoxemia and acidosis leading to the selection of cancer cell variants that are resistant to hypoxemia-induced apoptosis (often involving the loss of p53 expression). Tumor vessel walls have numerous openings, widened interendothelial junctions, and discontinuous or absent basement membrane. This contributes to the high permeability of these vessels and, together with lack of func­ tional intratumoral lymphatics, causes increased interstitial pressure within the tumor (which also interferes with the delivery of therapeutics to the tumor; Figs. 77-9, 77-10, and 77-11). Tumor blood vessels have a deficit of perivascular cells such as pericytes and smooth-muscle cells that normally regulate flow in response to tissue metabolic needs. Unlike normal blood vessels, the vascular lining of tumor vessels is not a homogeneous layer of ECs but often consists of a mosaic of ECs and tumor cells, which, because of their plasticity, can upregulate expres­ sion of genes normally only seen in ECs under hypoxic conditions. These cancer cell–derived vascular channels, which may be lined by ECM secreted by the tumor cells, are referred to as vascular mimicry. During tumor angiogenesis, ECs are highly proliferative and express a number of plasma membrane proteins that are characteristic of acti­ vated endothelium, including growth factor receptors and adhesion molecules such as integrins. These abnormalities in tumor vascula­ ture provide potential differential sensitivities from normal vessels to approaches inhibiting the process, allowing for the use of antiangio­ genic agents in cancer treatment. Lymphatic vessels also exist within tumors. Development of tumor lymphatics is associated with expression of VEGFR3 and its ligands VEGF-C and VEGF-D. The role of these vessels in tumor cell metas­ tasis to regional lymph nodes remains to be determined. However, VEGF-C levels correlate significantly with metastasis to regional lymph nodes in lung, prostate, and colorectal cancers. A. Normal blood vessel Low IP Normoxic Physiologic pH Hierarchical branching Even blood distribution Lumen EC BM BM Pericytes Tight junctions between EC Well-formed BM Pericyte coverage Normal permeability C. Treatment with bevacizumab (Early) D. Treatment with bevacizumab (Late) Low IP Less hypoxemia Less acidosis Normalization of vessels Improved blood flow Lumen EC BM Pericytes More efficient delivery of chemotherapy and oxygen Reduced permeability Death of EC due to loss of VEGF survival signals (plus chemotherapy or radiotherapy) Apoptosis of tumor due to starvation and/or effects of chemotherapy FIGURE 77-11  Normalization of tumor blood vessels due to inhibition of VEGF signaling. A. Blood vessels in normal tissues exhibit a regular hierarchical branching pattern that delivers blood to tissues in a spatially and temporally efficient manner to meet the metabolic needs of the tissue (top). At the microscopic level, tight junctions are maintained between endothelial cells (ECs), which are adherent to a thick and evenly distributed basement membrane (BM). Pericytes form a surrounding layer that provides trophic signals to the EC and helps maintain proper vessel tone. Vascular permeability is regulated, interstitial fluid pressure (IP) is low, and oxygen tension and pH are physiologic. B. Tumors have abnormal vessels with tortuous branching and dilated, irregular interconnecting branches, causing uneven blood flow with areas of hypoxemia and acidosis. This harsh environment selects genetic events that result in resistant tumor variants, such as the loss of p53. High levels of VEGF (secreted by tumor cells) disrupt gap junction communication, tight junctions, and adherens junctions between EC via src-mediated phosphorylation of proteins such as connexin 43, zonula occludens-1, VE-cadherin, and α/β-catenins. Tumor vessels have thin, irregular BM, and pericytes are sparse or absent. Together, these molecular abnormalities result in a vasculature that is permeable to serum macromolecules, leading to high tumor interstitial pressure, which can prevent the delivery of drugs to the tumor cells. This is made worse by the binding and activation of platelets at sites of exposed BM, with release of stored VEGF and microvessel clot formation, creating more abnormal blood flow and regions of hypoxemia. C. In experimental systems, treatment with bevacizumab or blocking antibodies to VEGFR2 leads to changes in the tumor vasculature that have been termed vessel normalization. During the first week of treatment, abnormal vessels are eliminated or pruned (dotted lines), leaving a more normal branching pattern. ECs partially regain features such as cell-cell junctions, adherence to a more normal BM, and pericyte coverage. These changes lead to a decrease in vascular permeability, reduced interstitial pressure, and a transient increase in blood flow within the tumor. Note that in murine models, this normalization period lasts only for ~5–6 days. D. After continued anti-VEGF/VEGFR therapy (which is often combined with chemo- or radiotherapy), ECs die, leading to tumor cell death (either due to direct effects of the chemotherapy or lack of blood flow). ■ ■ANTIANGIOGENIC THERAPY Angiogenesis inhibitors function by targeting the critical molecular pathways involved in EC proliferation, migration, and/or survival, many of which are highly expressed in the activated endothelium in tumors. Inhibition of growth factor and adhesion-dependent signaling B. Tumor blood vessel High IP High VEGF Hypoxemia Acidosis Tortuous vessels Haphazard blood flow Lumen EC Tumor cells Loss of EC junction complexes Irregular or no BM Absent (or few) pericyte Increased permeability CHAPTER 77 Collapse of tumor vasculature Cancer Cell Biology Lumen EC BM Tumor cells pathways can induce EC apoptosis with concomitant inhibition of tumor growth. Different types of tumors can use distinct combinations of molecular mechanisms to activate the angiogenic switch. Therefore, it is doubtful that a single antiangiogenic strategy will suffice for all human cancers; rather, a number of agents or combinations of agents Ang 1 Ang 2 Novel inhibitors Anti-VEGF MoAb VEGF VEGFR2 Kinase domain Tie2 receptor Enhanced binding to ECM, vessel stabilization Specific kinase inhibitors Proliferation survival migration Anti-integrin MoAb, RGD peptides αvβ3 αvβ5 α5β1 Nucleus Microtubules Extracellular matrix (ECM) 2-Methoxy estradiol MMPs (invasion, growth factor release) MMP inhibitors PART 4 Oncology and Hematology FIGURE 77-12  Knowledge of the molecular events governing tumor angiogenesis has led to a number of therapeutic strategies to block tumor blood vessel formation. The successful therapeutic targeting of VEGF and its receptors VEGFR is described in the text. Other endothelial cell (EC)–specific receptor tyrosine kinase pathways (e.g., angiopoietin/Tie2 and ephrin/EPH) are likely targets for the future. Ligation of the αvβ3 integrin is required for EC survival. Integrins are also required for EC migration and are important regulators of matrix metalloproteinase (MMP) activity, which modulates EC movement through the ECM as well as release of bound growth factors. Targeting of integrins includes development of blocking antibodies, small peptide inhibitors of integrin signaling, and arg-gly-asp–containing peptides that prevent integrin:ECM binding. Peptides derived from normal proteins by proteolytic cleavage, including endostatin and tumstatin, inhibit angiogenesis by mechanisms that include interfering with integrin function. Signal transduction pathways that are dysregulated in tumor cells indirectly regulate EC function. Inhibition of EGF-family receptors, whose signaling activity is upregulated in a number of human cancers (e.g., breast, colon, and lung cancers), results in downregulation of VEGF and IL-8, while increasing expression of the antiangiogenic protein thrombospondin-1. The Ras/MAPK, PI3K/Akt, and Src kinase pathways constitute important antitumor targets that also regulate the proliferation and survival of tumor-derived EC. The discovery that ECs from normal tissues express tissue-specific “vascular addressins” on their cell surface suggests that targeting specific EC subsets may be possible. will be needed, depending on distinct programs of angiogenesis used by different human cancers. Despite this, experimental data indicate that for some tumor types, blockade of a single growth factor (e.g., VEGF) may inhibit tumor-induced vascular growth. Bevacizumab, an antibody that binds circulating VEGF, modestly potentiates the effects of a number of different types of active chemo­ therapeutic regimens used to treat a variety of different tumor types including colon, lung, ovarian, and cervical cancers. It also has some activity in combination with immunotherapy against RCCs and alone for glioblastomas. Other protein inhibitors of the VEGF signaling path­ way approved for anticancer therapy include ramucirumab (a mono­ clonal antibody directed against VEGFR2, approved for use against gastric/gastroesophageal, colon, and lung cancers) and ziv-aflibercept (a recombinant protein inhibitor of VEGF, approved for colorectal cancer). Hypertension is the most common side effect of inhibitors of VEGF (or its receptors) but can be treated with antihypertensive agents and uncommonly requires discontinuation of therapy. Rare but seri­ ous potential risks include arterial thromboembolic events, including stroke and myocardial infarction, hemorrhage, bowel perforation, and inhibition of wound healing. Several small-molecule inhibitors (SMIs) that target VEGF RTK activity but are also inhibitory to other kinases have also been approved to treat certain cancers. Sunitinib (see above and Table 77-2) has activ­ ity directed against mutant c-Kit receptors (approved for GIST), but also targets VEGFR and PDGFR, and has antitumor activity against pancreatic neuroendocrine and metastatic RCCs, presumably on the basis of its antiangiogenic activity. Similarly, sorafenib, originally developed as a Raf kinase inhibitor but with potent activity against VEGFR and PDGFR, has activity against RCC, differentiated thyroid and hepatocellular cancers, and desmoid tumors. A closely related mol­ ecule to sorafenib, regorafenib, has activity against colorectal cancer, Stromal cell Novel inhibitors EPH receptor Ephrin-B2 Endothelial cell GIST, gastric, and hepatocellular cancers. Other inhibitors of the VEGF pathway approved for the treatment of various cancers include axitinib, pazopanib, lenvatinib, and cabozantinib. Antiangiogenic agents have been particularly effective against RCC for which angiogenic factors are important for its development and growth. The modest success in targeting tumor angiogenesis against most other cancers has led to enhanced enthusiasm for the develop­ ment of drugs that target other aspects of the angiogenic process; some of these therapeutic approaches are outlined in Fig. 77-12. An inhibitor of HIF2-α has sufficient antitumor activity against RCC, pancreatic neuroendocrine tumors, and hemangioblastomas develop­ ing in patients with germline VHL mutations to be approved for these indications. Evidence of enhanced activity has been seen when anti-VEGF agents are used in combination with immunomodulators including immune checkpoint inhibitors. Examples of approved combinations include durvalumab plus bevacizumab for HCC and lenvatinib plus pembrolizumab for endometrial cancer and RCC. ■ ■EVASION OF THE IMMUNE SYSTEM BY CANCERS The immune system plays a critical role in maintaining organismal integrity including by defending against pathogens as well as prevent­ ing and limiting the growth of cancers. There is a complex interaction between cancer and the host from the development of the first malig­ nant cell to the establishment of a clinical cancer and its subsequent growth, invasion, and metastasis. The immune system plays a critical role in the prevention of cancer development. This is exemplified by the increased risk for cancer development in individuals who are signifi­ cantly immunosuppressed, such as by inherited defects in mechanisms important for immune function, the immunosuppression necessary to maintain allogeneic organ transplants, and immunosuppression seen from certain infections such as human immunodeficiency virus. It also plays a critical role in inhibiting the process of cells metastasizing as well as growth of metastatic cells at the sites of metastasis. There are two components of the immune system. The first is innate immunity (present in the organism and not dependent on prior exposure to a specific antigen, such as those present in a pathogen or malignant cell), which tends to be general and not specific and a stimu­ lus is not remembered if encountered again. The second is the adaptive immune component, which depends on the innate immune process for activation and provides the specificity to the response with significant expansion of cells to target the specific antigens present on the patho­ gen or malignant cell and memory of the encounter such that exposure to the same stimulus elicits an even more rapid and vigorous response. Thus, while the innate process provides the first line of defense, the adaptive process is necessary for the specificity of response and provid­ ing memory to more rapidly attack cells should the pathogen infection recur or the malignant cells grow. The immune system has to be tightly regulated to allow for clearance of unwanted antigens while preventing an immune-mediated attack on the self. (See Chap. 360 for details on the function of the immune system.) Not surprisingly, since cancers arise from normal cells within the body that have a variety of processes to prevent harm or destruction by the immune system, they have a variety of mechanisms that allow them to evade detection and elimination by the immune system. These include downregulation of cell surface proteins involved in immune recognition (including MHC proteins and tumor-specific antigens), expression of other cell surface proteins that inhibit immune func­ tion (including members of the B7 family of proteins such as PD-L1), secretion of proteins and other molecules that are immunosuppressive such as TGF-β, recruitment and expansion of immunosuppressive cells such as regulatory T cells (which are important for maintaining tolerance against self-antigens), induction of T-cell tolerance, and downregulation of death receptors. Due to the marked heterogeneity of cells within a cancer, as well as the complexity and dynamic changes in the tumor microenvironment, a variety of immune-suppressive mechanisms are continuously occurring and changing. In addition, the inflammatory effects of some of the immune mediator cells in the tumor microenvironment (including tissue-associated macrophages and myeloid-derived suppressor cells) can suppress effector T-cell responses against the tumor as well as stimulate inflammation that can enhance tumor growth. There are marked differences in the way different malignancies respond to current immunotherapeutic approaches. For example, mel­ anomas, RCC, Merkel cell carcinomas, cancers with defects in DNA repair associated with microsatellite instability with accumulation of gene mutations, and lymphomas (including Hodgkin’s) respond well to current immunotherapeutic approaches, whereas microsatellite-stable pancreatic and colon cancers do not. While there is not a complete understanding of why these differences exist and many factors both within the cancer cells and in the microenvironment may play a role, several factors have been identified that appear to be important. These include the number of mutations present in the tumor (tumor mutational burden), presence of increased neoantigens, expression of immune checkpoint proteins (e.g., PD-L1 for anti-PD-1 or anti-PD-L1 therapy), density of tumor-infiltrating lymphocytes, and host genetic factors. One of these (PD-L1 expression by the tumor) has sufficient predictive value for certain tumors (e.g., non-small-cell lung cancer or gastroesophageal cancers) to be used in making treatment decisions regarding the use of antibodies targeting PD-1 or PD-L1. However, nei­ ther PD-L1 expression nor any other marker can predict responsive­ ness of most tumors to immunotherapy. Better biomarkers that define potential responsiveness of specific cancers to immunotherapy are badly needed. A major area of research is to try to identify approaches that would convert cancers that are not responsive to immunotherapy to being responsive. Immunotherapy approaches to treat cancer can be divided into those aimed at activating the immune response and those designed to release the brakes that prevent an effective immune response against tumors. Releasing the brakes is also important for maintaining the effectiveness of approaches that activate the immune response since, given the normally tight regulation of immune function, activation induces changes in the braking system to prevent the immune system from damaging normal tissues. Approaches at activating the immune response against cancer including using immunostimulatory mol­ ecules such as interferons, IL-2, and especially monoclonal antibod­ ies have had success in treating a number of different cancers. For example, antibodies that target molecules highly expressed on certain cancers, such as CD20 on malignant B cells or HER2 on a variety of cancers including breast and gastroesophageal cancers, which acti­ vate the immune response locally against those malignancies, have proven highly effective. A more direct approach to enhance the activity of T cells directed against specific tumors involves isolating T cells from patients and reengineering the cells to express chimeric antigen receptors (CAR-T) that recognize antigens present on the cells of that individual’s tumor. The most commonly used approach to date has been to engineer the cells to express receptors targeting the CD19 antigen on ALL, dif­ fuse large B-cell lymphoma (DLBCL) cells, follicular lymphoma, and mantle cell lymphoma. These have been shown to have significant antitumor activity in the treatment of patients with ALL and DLBCL, including durable remissions in patients refractory to standard thera­ pies, and are approved for these malignancies. In addition, anti-B-cell maturation antigen (BCMA) CAR-T therapies have been approved for the treatment of multiple myeloma. CHAPTER 77 However, there have also been significant issues with toxicity including cytokine release syndrome, organ toxicity felt to be due to inadvertent targeting of antigens present in the organ, neurotoxicity, and potentially an increased risk for subsequent development of T-cell malignancies. These patients often require aggressive supportive care by individuals experienced in the delivery of CAR-T therapy. In addi­ tion, as is true for most anticancer therapies, mechanisms of resistance have developed, most commonly the outgrowth of tumor cells no longer expressing the antigen. Mechanisms for preventing the devel­ opment of resistant cells are being explored, including combinations targeting different antigens. In addition to potentially preventing or overcoming resistance to the targeting of a single antigen, this could potentially increase efficacy and better reflects the normal immune response to pathogens or cancers in targeting multiple different anti­ gens. CAR-T therapies are undergoing clinical investigation against other hematologic malignancies and solid tumors. Approaches to develop allogeneic CAR-T therapies are also being explored with the aim of having an off-the-shelf product that could be used in a number of patients rather than generating each treatment specifically for one recipient. Cancer Cell Biology Another approach utilizing lymphocytes to treat cancer involves utilization of autologous tumor-derived T cells. Tumor-infiltrating lymphocyte therapy in combination with IL-2 is now approved for the treatment of melanoma. Given previously demonstrated efficacy against other cancers, such as RCC, tumor-infiltrating lymphocyte therapy may eventually be approved for other cancers as well. However, technical issues of getting adequate expansion of the cells may limit this approach. The immune response against cancers may also be able to be enhanced through targeting of proteins or cells (e.g., regulatory T cells) involved in normal homeostatic control to prevent autoimmune damage to the host but that malignant cells and their stroma can also utilize to inhibit the immune response directed against them. A component of this process includes a number of immune checkpoints that involve interaction of proteins on the surface of effector T cells with proteins on self-cells (or cancer cells that arise from normal cells) that inhibit activation of the T cells. By inhibiting the binding of the proteins involved in this process, the brake on the effector T cells are released and they can be activated. The presence of neoantigens (e.g., mutant proteins) enhances the activation of the T cells against cancer cells as compared to normal cells. Sufficient clinical antitumor activity has been seen for monoclonal antibodies targeting various proteins involved in this process, including CTLA-4, PD-1, PD-L1, and LAG3 (others continue to be explored), for them to be approved. These are Tumor cells Elaboration of immunosuppressive cytokines TGF-β Interleukin-4 Interleukin-6 Interleukin-10 Immunosuppressive immune cells PART 4 Oncology and Hematology T regulatory cells CD11+ granulocytes Macrophages FIGURE 77-13  Tumor-host interactions that suppress the immune response to the tumor. co-inhibitory molecules that are expressed on the surface of cancer cells, and/or cells of the immune system, and/or stromal cells and are involved in inhibiting the immune response against both normal cells (their normal protective mechanism for the host) and also cancer cells that use this inhibitory process to evade immune-mediated cell death (Figs. 77-13 and 77-14). This approach has had clinical activity against a wide variety of cancers. A monoclonal antibody directed against CTLA-4 is approved for the treatment of melanoma and several other malignancies, and antibodies targeting PD-1 or PD-L1 are approved for use against melanoma, RCC, lung cancer (both non-small-cell lung and small-cell lung), head and neck cancer, nasopharyngeal cancer, urothelial cancer, cervical cancer, endometrial cancer, hepatocellular carcinoma, gastric cancer, esophageal cancer, cutaneous squamous cell carcinoma, basal cell carcinoma, Merkel cell cancer, primary B-cell mediastinal lymphoma, Hodgkin’s lymphoma, and in a cancer-agnostic PD-L1 PD-L1 Cancer cells CD28 CD80/86 MHC - CD80/86 CTLA-4 Tumor antigens (TA) Antigen-presenting cell/dendritic cell FIGURE 77-14  Inhibition of T-cell activation against cancer cells by engagement of co-inhibitory molecules including PD-1, PD-L1, and CTLA-4 and reversal of this inhibition by antibodies against these proteins. The red ovals in the T cell indicate inhibitory signals, and the green oval indicates stimulatory signals. T-cell inactivation Induction of CTLA-4 Induction of PD-1 Cell signaling disruption Class I MHC loss in tumor cells STAT-3 signaling loss in T cells Generation of indoleamine 2, 3-dioxygenase Degradation of T-cell receptor ζ chain approach, cancers with high microsatellite instability (MSI) or high tumor mutational burden (TMB). They continue to be evaluated against other malignancies as well. The combination of anti-CTLA-4 and anti-PD-1 antibodies has been approved for treatment of a number of malignancies, including mela­ noma, RCC, HCC, NSCLC, mesothelioma, and MSI-high metastatic colorectal cancers. Specific determinants of response to immune checkpoint inhibitors are still being defined, but in addition to high PD-L1 expression, the presence of increased neoantigens in the tumor, such as seen in patients with MSI-high and TMB-high cancers, may be one important determinant of better responses. A number of other proteins are involved in controlling the immune response (both ones that enhance activity [e.g., CD27 and CD40] as well as ones involved in inhibiting response [e.g., TIM-3, TIGIT]). Antibodies have been developed to modulate function of these Anti-PD-L1 antibodies Anti-PD-1 antibodies PD-1 + – PD-1 + + MHC T-cell receptor T cell receptor – + Cancer cell T cell Anti-CTLA-4 antibodies # 07 - 78 Principles of Cancer Treatment ### 78 Principles of Cancer Treatment proteins, and many are in clinical development for cancer therapy. In addition, various combinations targeting more than one protein involved in modulating the immune response against cancers or with other anticancer approaches (targeted agents, chemotherapy, radia­ tion therapy) that may lead to enhanced antitumor activity are also being explored. An important aspect of these approaches is balancing sufficient release of the negative control of the immune response to allow immune-mediated attack on the tumors while not allowing too much of an immune response against normal tissues and thus induc­ ing severe autoimmune effects (e.g., against lung, liver, skin, thyroid, pituitary gland, gastrointestinal tract, or other organs). As is true for other immunotherapeutic approaches against cancer, major efforts are ongoing to better understand the mechanism of immune toxicity from these approaches and, therefore, ways of controlling this while not abrogating the antitumor effects. Improved knowledge of the biology of the interactions between the immune system and cancers continues to be rapid with the promise for additional significant improvements in use of immunotherapy to treat cancer. Given the success of vaccines against multiple viruses, many efforts have been made over decades to develop anticancer vaccines that would induce a sufficient immune response to lead to killing of cancer cells or even potentially prevention. This has been largely unsuccessful for the treatment of established cancers, although three vaccines are approved for use in cancer care: bacillus Calmette-Guérin (BCG) for intravesical treatment of superficial bladder cancer, sipuleucel-T for prostate can­ cer, and talimogene laherparepvec for direct injection into melanoma. Except for BCG, and then only for superficial bladder cancer, these have had relatively limited effectiveness. Perhaps more promising are vaccines combined with other forms of immunotherapy. Benefit may be enhanced by using a vaccine in combination with immune checkpoint inhibition therapy to delay recurrence of resected high-risk melanoma and provides hope that this approach may be effective in the future. However, further studies are needed to confirm this. IMPACT OF UNDERSTANDING CANCER BIOLOGY ON PREVENTION AND EARLY DETECTION The biggest impacts on decreasing cancer mortality come from pre­ vention followed by early detection. In addition to the critical role that new knowledge about cancer biology has in developing improved treatment approaches, it is also critical in enhancing preventative and early detection approaches. Examples in prevention include using knowledge about the roles of certain viruses in the development of some cancers to create vaccines for viruses (e.g., hepatitis B virus and human papillomavirus) to decrease the risk of developing cancer from these infections and using knowledge about how certain carcinogens cause cancer to work on controlling or eliminating carcinogenic agents (e.g., cigarette smoking and asbestos). The development of sensitive methods for detecting circulating tumor DNA holds promise for earlier detection of cancer, although this has not yet been firmly established. Imaging agents for specific tissues (such as the use of proteins highly expressed on specific cancer tissues including prostate-specific mem­ brane antigen PET imaging to detect prostate cancer or HER2 to detect a subset of breast, gastric, and other cancers) or potentially against mutant proteins found in cancers (e.g., KRAS or p53 mutations) hold promise for earlier and more specific detection of cancer. As more is learned about cancer biology, this knowledge will also continue to be applied in preventative and early detection strategies. SUMMARY Just as human biology is complex, cancer biology is complex. Although each of the biological aspects of cancers and examples of targeting them has been addressed individually, clearly there is complicated cross-talk between these that occurs in all cancers that needs to be better understood to optimally treat different cancers. The explosion of information on tumor cell biology, metastasis, and tumor-host interactions (including angiogenesis, other tumor-stromal interactions, and immune evasion by tumors) has ushered in a new era of rational targeted therapy for cancers as well as the potential for individualized therapy. Furthermore, it has become clear that specific molecular fac­ tors detected in individual tumors (gene mutations, gene expression profiles, miRNA expression, overexpression of specific proteins) can be used to tailor therapy and maximize antitumor effects. Potentially of even greater impact on decreasing deaths from can­ cer, better understanding of the biology of early cancer development should ultimately lead to better approaches for prevention. And tech­ nologic development to improve sensitivity and specificity in detect­ ing cancer-specific molecules (e.g., mutated genes) provide hope that approaches for earlier detection of cancer can be developed. ■ ■FURTHER READING Agudo J et al: Targeting cancer cell dormancy. Nat Rev Cancer 24:97, 2024. Bhullar KS et al: Kinase-targeted cancer therapies: Progress, chal­ lenges and future directions. Mol Cancer 17:48, 2018. de Visser KE, Joyce JA: The evolving tumor microenvironment: From cancer initiation to metastatic outgrowth. Cancer Cell 41:374, 2023. Finley LWS: What is cancer metabolism? Cell 186:1670, 2023. Fujii M et al: Decoding the basis of histological variation in human cancer. Nat Rev Cancer 24:141, 2024. Gacche RN: Changing landscape of anti-angiogenic therapy: Novel approaches and clinical perspectives. Biochim Biophys Acta Rev Cancer 1878:189020, 2023. Gerstberger S et al: Metastasis. Cell 186:1564, 2023. Hanahan D: Hallmarks of cancer: New dimensions. Cancer Discov CHAPTER 78 12:31, 2022. Matthews HK et al: Cell cycle control in cancer. Nat Rev Mol Cell Principles of Cancer Treatment Biol 23:74, 2022. Pottier C et al: Tyrosine kinase inhibitors in cancer: Breakthrough and challenges of targeted therapy. Cancers (Basel) 12:731, 2020. Prager BC et al: Cancer stem cells: The architects of the tumor ecosystem. Cell Stem Cell 24:41, 2019. Reiter JG et al: An analysis of genetic heterogeneity in untreated cancers. Nat Rev Cancer 19:639, 2019. Romesser PB, Lowe SW: The potent and paradoxical biology of cellular senescence in cancer. Annu Rev Cancer Biol 7:207, 2023. Sharma P, et al: Immune checkpoint therapy: Current perspectives and future directions. Cell 186:1652, 2023. Tomuleasa C et al: Therapeutic advances of targeting receptor tyro­ sine kinases in cancer. Sig Transduct Target Ther 9:201, 2024. Yang K et al: Antigen presentation in cancer: Mechanisms and clinical implications for immunotherapy. Nat Rev Clin Oncol 20:604, 2023. Yuan J, Ofengeim D: A guide to cell death pathways. Nat Rev Mol Cell Biol 25:379, 2024. Edward A. Sausville, Dan L. Longo Principles of Cancer Treatment CANCER PRESENTATION Localized or systemic cancer is frequent in the differential diagnosis of a variety of common complaints. Affording patients the greatest opportunity for cure or meaningful prolongation of life is greatly aided by diagnosis of cancer early in its natural history. The spectrum of possible cancer-related interventions to make cure possible is shown in Table 78-1. ■ ■DETECTION OF A CANCER The term cancer, as used here, is synonymous with the term tumor, whose original derivation from Latin simply meant “swelling,” not TABLE 78-1  Spectrum of Cancer-Related Interventions Asymptomatic patient screening (breast, cervix, colon, some lung) Consideration of cancer in a differential diagnosis Physical examination, imaging, or endoscopy to define a possible tumor Phlebotomy for molecular studies and circulating tumor cell characterization Diagnosis of cancer by biopsy or removal:   Routine histology   Specialized histology: immunohistochemistry   Molecular studies   Cytogenetic studies Staging the cancer: Where has it spread? Imaging (computed tomography, magnetic resonance imaging, positron emission tomography) Treatment   Localized (surgical removal with or without local radiation therapy and/or topical therapy; may be curative)   Local plus systemic, multimodality: cure advanced disease, reverse organ compromise   Systemic, adjuvant (cure micrometastases; all evident disease has been locally treated)   Systemic, neoadjuvant (before local therapy to improve local and systemic results)   Systemic, palliative (improve symptoms, quality of life, progression-free PART 4 Oncology and Hematology survival) Supportive care   During treatment: related to tumor effects on patient   During treatment: to counteract side effects of treatment After treatment: to ameliorate the adverse effects of treatment Palliative and end of life   When useful treatments are not feasible or desired otherwise specified. Swelling reflects increased interstitial fluid pres­ sure and increased cellular and stromal mass, compared to normal tissue. Leukemia, a cancer of the blood-forming tissues, presents in a disseminated form frequently without tumor masses. Tumors can also present by organ dysfunction, such as dyspnea on exertion from anemia caused by leukemia replacing normal marrow, cough from lung cancers, jaundice from tumors blocking bile ducts, or neurologic signs from gliomas. Hemorrhage frequently results from involvement of hollow viscera, but also may reflect altered platelet number or blood coagulation. Tumors may also present with a “paraneoplastic syn­ drome” owing to the effects of substances the tumor secretes. Although the fraction of patients with cancer as the basis for a presenting sign or symptom may be low, the implications of missing an early-stage tumor call for considering cancer as a basis for persistent signs or symptoms. Evidence of a tumor’s existence can come from careful physical examination, e.g., enlarged lymph nodes in lymphomas or palpable mass in a breast or soft tissue site. A mass may also be detected or con­ firmed by an imaging modality (e.g., x-ray, magnetic resonance imag­ ing [MRI], or ultrasound). Endoscopy may directly visualize a tumor. ■ ■ESTABLISHING A CANCER DIAGNOSIS Once a potential tumor is defined, establishing the diagnosis is the next step. This requires a biopsy procedure in most circumstances and pathologic confirmation that cancer is present; very rarely, where biopsy would be definitely injurious and imaging modalities are unequivocal, such as with a likely brainstem glioma, treatment might be reasonably considered based on clinical and imaging evidence with­ out biopsy. In addition to light microscopy, biopsied tissue also allows definition of genetic abnormalities and protein expression patterns to recommend best treatment (Table 78-2). The extent of specialized testing needs to be tailored to an individual patient’s case. Global DNA sequencing of genes expressed in tumors has not been shown to convey conclusive advantage in terms of sur­ vival. But the aggregate “mutational burden” present in tumors and the intactness of DNA repair genes (e.g., breast cancer susceptibility 1 TABLE 78-2  Diagnostic Biopsy: Standard-of-Care Molecular and Special Studies to Be Considered All solid tumors   Tumor mutational burden   Microsatellite instability DNA repair pathway intactness   Homologous recombination DNA repair pathway intactness Breast cancer: primary and suspected metastatic   Breast cancer susceptibility 1 and 2 (BRCA1/2) gene mutations   Hormone receptor expression: estrogen, progesterone   HER2/neu oncoprotein   PI3KA mutation status Lung cancer: primary and suspected metastatic   If nonsquamous non-small-cell:     Epidermal growth factor receptor (EGFR) mutation     ALK, ROS1, NRTK, NRG1 gene fusion     BRAF V600E mutation     Programmed cell death ligand 1 (PD-L1) expression Colon cancer: suspected metastatic   KRAS mutation   BRAF V600E mutation Gastrointestinal stromal tumor   KIT mutation Melanoma   BRAF mutation   c-kit expression and KIT mutation if present Pancreatic cancer   BRCA1/2 mutation Prostate cancer   BRCA1/2 mutation Thyroid cancer   RET gene alterations (mutations, translocations, amplification) Gliomas   1p/19q co-deletion   Alkylguanine alkyltransferase promoter methylation   Isocitrate dehydrogenase 1 and 2 mutation Leukemia (peripheral blood mononuclear cells and/or bone marrow)   Cytogenetics   Flow cytometry   Treatment-defining chromosomal translocations/mutations     Bcr-Abl fusion protein     t(15;17)     Inversion 16     t(8;21)   FMS-associated tyrosine kinase (FLT3) mutation   Nucleophosmin gene mutational status   Isocitrate dehydrogenase 1 and 2 mutation Lymphoma   Immunohistochemistry for CD20, CD30, and B- and T-cell markers   Treatment-defining chromosomal translocations:     t(14;18)     t(8;14)   Translocations involving ALK gene and 2 [BRCA1/2], microsatellite instability, homologous recombination pathway–associated genes) may suggest valuable treatment courses in tumors without curative potential. Optimally, an excisional biopsy occurs, in which the entire tumor mass is removed with a margin of normal tissue surrounding it. If an excisional biopsy cannot be performed, incisional biopsy is the proce­ dure of second choice: a wedge of tissue is removed, trying to include the majority of the cross-sectional diameter to minimize sampling error. Biopsy techniques that involve cutting into tumor risk facilitating the spread of the tumor. Consideration with a surgeon of whether the biopsy approach is a potential prelude to a curative surgery may inform the approach taken. Core-needle biopsy usually obtains considerably less tissue but can provide information to plan a treatment. Fine-needle aspiration generally yields a suspension of cells from a mass. If positive for cancer, it may allow inception of systemic treatment, or it can pro­ vide a basis for planning a more extensive surgical procedure. A “negative” fine-needle aspiration cannot be taken as definitive evidence that a tumor is absent. In some instances, features of diagnostic imaging are sufficient to make a reliable diagnosis without obtaining tissue, usually with presence of a tumor-associated circulating diagnostic marker, e.g., α fetoprotein in hepatocellular carcinoma or prostate-specific antigen (PSA) in prostate cancer with apparent typical metastatic disease. ■ ■CANCER STAGING Defining the extent of disease determines whether localized treat­ ments, “combined-modality” approaches, or systemic treatments should initially be considered. Radiographic and other imaging tests can be helpful in defining the clinical stage; pathologic staging docu­ ments the histologic presence of tumor in tissue biopsies. Lymph node sampling in breast cancer, melanoma, lung, head and neck, colon, and other intra-abdominal cancers may provide crucial information. Staging systems define a “T” component related to the size of the tumor or its invasion into local structures, an “N” component related to the number and nature of lymph node groups with tumor involve­ ment, and an “M” component, based on the presence of local or distant metastatic sites. The various TNM components are then aggregated to stages, usually stage I to III or IV, depending on the anatomic site. The numerical stages reflect similar long-term survival outcomes of the respective TNM grouping stage after treatment tailored to the stage. In general, stage I tumors are T1 (reflecting small size), N0 or N1 (reflect­ ing no or minimal node spread), and M0 (no metastases). Such earlystage tumors are usually amenable to curative approaches with local treatments. On the other hand, stage IV tumors have metastasized to distant sites or locally invaded viscera in a nonresectable way. They are treated with palliative intent, except for those diseases with exceptional sensitivity to systemic treatments such as chemotherapy or immuno­ therapy. Also, the TNM staging system is not useful in diseases such as leukemia, where bone marrow infiltration is never localized, or central nervous system (CNS) tumors, where tumor histology and the extent of feasible resection are more important in driving prognosis. CANCER TREATMENT The goal of cancer treatment is first to eradicate the cancer. If this is not possible, the goal shifts to palliation: amelioration of symptoms and preservation of quality of life while striving to extend life. When cure of cancer is possible, cancer treatments may be undertaken despite the certainty of severe toxicities, but these may produce toxicity with no benefit. Conversely, when the clinical goal is palliation, careful atten­ tion to minimizing the toxicity of treatments becomes a significant goal. The two main types of cancer treatment are local and systemic. Local treatments include surgery, radiation therapy (including photody­ namic therapy), and ablative approaches, including radiofrequency and thermal or cryosurgical approaches. Systemic treatments include che­ motherapy (including hormonal therapy and molecular targeted ther­ apy) and biologic therapy (including immunotherapy). The modalities are often used in combination. Oncology, the study of tumors including treatment approaches, is a multidisciplinary effort with surgical, radia­ tion, and internal medicine–related areas of oncologic expertise. Normal organs and cancers share the property of having a popula­ tion of cells actively progressing through the cell cycle, with their divi­ sion providing a basis for organ or tumor growth, and a population of cells not in cycle; these include stem cells, whose properties are being elucidated. Cancer stem cells serve as a basis for tumor initiating or repopulating cells. Tumors follow a Gompertzian growth curve (Fig. 78-1), with the growth fraction of a neoplasm high with small tumor burdens but declining until, at the usual time of diagnosis (tumor burden of 1–5 × 109) the growth fraction is only 1–4% for many Growth fraction Growth rate Percent of maximum Lethal Tumor size Clinically detectable Tumor burden logs of cells Time, days FIGURE 78-1  Gompertzian tumor growth. The growth fraction of a tumor declines exponentially over time (top), peaking before it is clinically detectable (middle). Tumor size increases slowly, goes through an exponential phase, and slows again as the tumor has limitation of nutrients or host regulatory influences occur. The maximum growth rate occurs at 1/e, the point at which the tumor is about 37% of its maximum size (marked with an X). Tumor becomes detectable at a burden of about 109 (1 cm3) cells and kills the patient at a tumor cell burden of about 1012 (1 kg). CHAPTER 78 solid tumors. Thus the most rapid growth rate occurs before the tumor is detectable. An alternative explanation for such growth properties may also emerge from the ability of tumors at metastatic sites to recruit circulating tumor cells from the primary tumor or other metastases. Key features of tumor growth are the ability to stimulate new sup­ porting stroma through angiogenesis and ingrowth of fibroblasts and immune cells (Chap. 77). Principles of Cancer Treatment LOCALIZED CANCER TREATMENTS ■ ■SURGERY Surgery is the most effective means of treating cancer. At least 40% of cancer patients are cured by surgery. Unfortunately, many patients with solid tumors have disease not practically removable. “Palliative” surger­ ies, however, may afford local control of tumor, preserve organ func­ tion, and achieve debulking that permits more effective subsequent therapy, while allowing more detailed staging. Cancer surgery aiming for cure is usually planned to excise the tumor completely with an adequate margin of normal tissue (the margin varies with the tumor and the anatomy). Such a resection is defined as an R0 resection. R1 and R2 resections, in contrast, are imprecisely defined pathologically as having microscopic or macroscopic, respectively, tumor at resection margins. Such outcomes may be the basis for reoperation to obtain optimal mar­ gins if feasible and of likely clinical utility. Extending the procedure to resect draining lymph nodes obtains prognostic information and may, in some anatomic locations, improve survival. Laparoscopic approaches are being used for primary abdominal and pelvic tumors, although with certain tumors (e.g., uterine and cervix), controversy exists as to the desirability of laparoscopic tumor removal. Lymph node spread may be assessed using the sentinel node approach, in which the first draining lymph node is defined by injecting a dye or radioisotope into the tumor site at operation and then resecting the first node to turn blue or collect isotope. Sentinel node assess­ ment appears to provide information without the risks (lymphedema, lymphangiosarcoma) associated with resection of all regional nodes. Advances in adjuvant chemotherapy (given systemically after removal of all local disease without evidence of metastatic disease) and radia­ tion therapy following surgery have permitted a decrease in the extent of primary surgery. Thus, “lumpectomy” with radiation therapy is as effective as modified radical mastectomy for breast cancer, and limbsparing surgery followed or preceded by adjuvant radiation therapy and chemotherapy has replaced amputation for most childhood rhabdomyosarcomas and osteosarcomas. More limited surgery spares organ function, as in larynx and bladder cancer. In some settings (e.g., bulky testicular cancer or stage III breast cancer), surgery is not the first treatment modality used. After diagnostic biopsy, chemotherapy and/or radiation therapy is delivered, followed by a surgical procedure to remove residual masses; this is called neoadjuvant therapy. Coordi­ nation among the surgical oncologist, radiation oncologist, and medi­ cal oncologist is crucial. Surgery may be curative in a subset of patients with metastatic disease. Patients with limited lung metastases from osteosarcoma may be cured by resection of the lung lesions. In patients with colon cancer who have fewer than five liver metastases restricted to one lobe and no extrahepatic metastases, hepatic lobectomy may produce longterm disease-free survival in 25% of selected patients. In the setting of hormonally responsive tumors, oophorectomy may eliminate estrogen production, and orchiectomy may reduce androgen production, hor­ mones that drive many breast and all prostate cancers, respectively. In selecting a surgeon or center for primary cancer treatment, consid­ eration must be given to the volume of cancer surgeries undertaken by the site. Studies in a variety of cancers have shown that increased annual procedure volume appears to correlate with outcome. Surgery is used in a number of ways for palliative or supportive care of the cancer patient. These include insertion and care of central venous catheters, control of pleural and pericardial effusions and ascites, caval interruption for recurrent pulmonary emboli, stabilization of cancerweakened weight-bearing bones, and control of hemorrhage, among others. Surgical bypass of gastrointestinal, urinary tract, or biliary tree obstruction or spinal cord decompression can alleviate symptoms and may prolong survival. Splenectomy may relieve symptoms and reverse hypersplenism. Intrathecal or intrahepatic therapy relies on surgical placement of appropriate infusion portals. Surgery may correct other treatment-related toxicities such as adhesions or strictures. Plastic and reconstructive surgery can correct the effects of disfiguring primary treatment. Surgery is also a tool valuable in the prevention of cancers in high-risk populations. Prophylactic mastectomy, colectomy, oopho­ rectomy, and thyroidectomy are mainstays of cancer prevention in inherited cancer susceptibility syndromes. PART 4 Oncology and Hematology ■ ■RADIATION Radiation Biology and Medicine  Therapeutic radiation is gen­ erally ionizing, causing breaks in DNA and generation of free radicals from cell water that damage cancer cell membranes, proteins, and organelles. Ionizing radiation + H2O → H2O+ + e− H2O+ + H2O → H3O+ + OH• OH• → cell damage Radiation damage is augmented by oxygen; hypoxic cells are more resistant. X-ray and gamma-ray photons are the forms of ionizing radiation most commonly used to treat cancer. Particulate ionizing radiation using protons has also become available. Radiation dose is quantitated based on the amount of energy absorbed by the tumor, not on radiation generated by the machine. The International System (SI) unit for radiation dose is the Gray (Gy): 1 Gy refers to 1 J/kg of tissue; 1 Gy equals 100 centigrays (cGy) of absorbed dose. A historically used unit appearing in the oncology literature, the rad (radiation absorbed dose), is defined as 100 ergs of energy absorbed per gram of tissue and is equivalent to 1 cGy. Radiation dose is measured by placing detectors at the body surface or in radiated phantoms that resemble human form and substance. The features that make a particular cell more or less sensitive to radiation involve DNA repair proteins that, in their physiologic role, protect against environ­ mentally related DNA damage. Localized Radiation Therapy  Radiation effect is influenced by three determinants: total absorbed dose, number of fractions, and time of treatment. A typical course of radiation therapy should be described as 4500 cGy delivered to a particular target (e.g., mediastinum) over 5 weeks in 180-cGy fractions. Most curative radiation treatment programs are delivered once a day, 5 days a week, in 150- to 200-cGy fractions. Nondividing cells are more resistant than dividing cells; delivering radiation in repeated fractions is done to expose a larger number of tumor cells that have entered the division cycle. The energy of the radiation determines its ability to penetrate tissue. Low-energy x-rays (150–400 kV) scatter when they strike the body, resulting in more damage to adjacent normal tissues and less radiation deliv­ ered to the tumor. Megavoltage radiation (>1 MeV) has very low lateral scatter; this produces a skin-sparing effect, more homogeneous distribution of the radiation energy, and greater deposit of the energy in the tumor, or target volume. The transit volume includes the tissues through which the beam passes to the target volume. Computational approaches and delivery of many beams to converge on a target volume are the basis for “gamma knife” and related approaches to deliver high doses to tumor, sparing normal tissue. Therapeutic radiation is delivered in three ways: (1) teletherapy, with focused beams of radiation generated at a distance and aimed at the tumor within the patient; (2) brachytherapy, with encapsulated sources of radiation implanted directly into or adjacent to tumor tissues; and (3) systemic therapy, with radionuclides administered, for example, intravenously but perhaps targeted by some means to a tumor site. For example, systemically administered isotopes of iodide have an impor­ tant role in the treatment of thyroid neoplasms, owing to the selective upregulation of the iodide transporter in the tumor cell compartment. Likewise, isotopes of samarium and radium have been found useful in the palliation of bony metastases of prostate cancer owing to their selective deposition at the tumor-bone matrix interface. Teletherapy with x-ray or gamma-ray photons is the most commonly used form of radiation therapy and also delivers particulate forms of radiation such as proton beams. The difference between photons and protons relates to volume with greatest delivery of energy: protons have a narrow range of energy deposition. Electron beams are a particulate form of radiation that, in contrast to photons and protons, have a very low tissue penetrance and are used to treat cutaneous tumors. Certain drugs used in cancer treatment may also act as radiation sensitizers. For example, compounds that incorporate into DNA (e.g., halogenated pyrimidines, cisplatin) augment radiation effects at local sites and are important adjuncts to radiation of certain tumors (e.g., squamous head and neck, uterine cervix, and rectal cancers). Toxicity of Radiation Therapy  Although radiation therapy is most often administered to a local region, systemic effects, including fatigue, anorexia, nausea, and vomiting, may develop that are related in part to the volume of tissue irradiated, dose fractionation, radiation fields, and individual susceptibility. Radiation-injured tissues release cytokines that act systemically to produce these effects. Bone is among the most radio-resistant organs, with radiation effects being manifested mainly in children through premature fusion of the epiphyseal growth plate. By contrast, the male testis, female ovary, and bone marrow are the most sensitive organs. Any bone marrow in a radiation field will be eradicated by therapeutic irradiation. Organs with less need for cell renewal, such as heart, skeletal muscle, and nerves, are more resistant to immediate radiation effects. In radiation-resistant organs, the vas­ cular endothelium is the most sensitive component. Acute toxicities include mucositis, skin erythema (ulceration in severe cases), and bone marrow toxicity. Often these can be alleviated by periodic interruption of treatment. Chronic toxicities are more serious. Radiation of the head and neck region produces thyroid failure; cataracts and retinal damage can lead to blindness; salivary glands stop making saliva, which leads to dental caries and poor dentition. Mediastinal irradiation increases myocardial vascular disease. Other late vascular effects include chronic constric­ tive pericarditis, lung fibrosis, viscus stricture, spinal cord transection, and radiation cystitis or enteritis. A serious late toxicity is the development of hematologic tumors or second solid tumors in or adjacent to the radiation fields. Such tumors can develop in any organ or tissue and occur at a rate of ~1% per year beginning in the second decade after treatment. ■ ■OTHER LOCALIZED CANCER TREATMENTS Endoscopy allows placement of stents to unblock viscera, palliating, for example, gastrointestinal or biliary obstructions. Radiofrequency ablation (RFA) refers to microwave nonionizing radiation to induce thermal injury within a volume of tissue. RFA can be useful in the con­ trol of metastatic lesions, particularly in liver, that may threaten biliary drainage. Cryosurgery uses extreme cold to sterilize lesions in certain sites, such as prostate and kidney, at a very early stage, eliminating the need for modalities with more side effects such as surgery. Some chemicals (porphyrins, phthalocyanines) are preferentially taken up by cancer cells. When intense light, delivered by a laser, is shone on cells containing these compounds, free radicals are gener­ ated and the cells die. Such phototherapy is used to treat skin cancer; ovarian cancer; and cancers of the lung, colon, rectum, and esophagus. Palliation of recurrent locally advanced disease can sometimes be dra­ matic and last many months. Infusion of chemotherapeutic or biologic agents or radiationbearing delivery devices such as isotope-coated glass spheres into local sites through catheters have been used to treat disease limited to that site; in selected cases, prolonged control of truly localized disease has been possible. SYSTEMIC CANCER TREATMENTS The concept that systemically administered chemicals might have a useful effect on cancers was historically derived from three sets of observations. Paul Ehrlich in the nineteenth century observed that different dyes reacted with different cell and tissue components. He hypothesized the existence of “magic bullets” that might bind to tumors, owing to the affinity of the agent for the tumor. Observation of the toxic effects of certain mustard gas derivatives on the bone mar­ row during World War I suggested that smaller doses of these agents might be used to treat tumors of marrow-derived cells. Finally, the fact that tumors from hormone-responsive tissues, e.g., breast tumors, could shrink after oophorectomy led to the idea that endogenous or exogenous substances might modulate tumor growth by altering its regulatory biology. Chemicals achieving each of these goals are cur­ rently used as cancer chemotherapy agents. Anecdotal reports of tumor regression following intratumoral injection of bacterial extracts raised the possibility of immune system– mediated tumor regression. Serotherapy of infectious disease in the preantibiotic era encouraged analogous efforts to develop vaccine- and antibody-based treatments for cancer. Administration of autologous immune cells obtained by pheresis procedures from a patient or puri­ fied from a patient’s removed tumor, activated by cytokines ex vivo, achieved durable disease control in a small fraction of patients with certain tumors, particularly renal cell cancers or melanoma. These observations provided the rationale for more modern efforts to treat tumors using cell-mediated immunity. Systemic cancer treatments are of three broad types. Cytotoxic chemotherapy agents are “small molecules” (generally with molecular mass <1500 Da) that cause major regression of experimental tumors growing in animals. These agents mainly target DNA structure or segregation of chromosomes in mitosis. Cancer molecular target therapies refer to small molecules designed and developed to interact with a defined macromolecule important in maintaining the malig­ nant state. As described in Chap. 77, successful tumors have activated biochemical pathways that lead to uncontrolled proliferation through the action of hormone receptor proteins, oncogene products, loss of cell cycle inhibitors, or loss of cell death regulation, and have acquired the capacity to replicate chromosomes indefinitely, invade, metasta­ size, and evade the immune system. Cancer biologic therapies are most frequently macromolecules, cells, or cell extracts that have a particular target (e.g., anti–growth factor receptor, cytokine, or immunomodula­ tory antibodies) or may have the capacity to induce a host immune response to kill tumor cells. Most recent additions to cancer biologic therapies include genetically modified cells that directly attack tumor cells and tumor-infecting viruses that can kill tumor cells but also elicit host antitumor immune responses. ■ ■SYSTEMIC CANCER THERAPY OVERVIEW General Principles  The therapeutic index of any drug is the degree of separation between toxic and therapeutic doses. Really useful drugs have large therapeutic indices, and this usually occurs when the drug target is expressed in the disease-causing compartment as opposed to the normal compartment. Cytotoxic chemotherapeutic agents have the unfortunate property that their main targets, DNA and microtubules, are present in both normal and tumor tissues. Therefore, they have relatively narrow therapeutic indices. Targeted agents can also cause effects on their target in normal tissues, or “off-target” effects on unre­ lated targets in organs experiencing damage. Biologic therapies may elicit misdirected immune responses on normal organ function. A key activity in oncology drug development is striving to administer a dose that can convey benefit with a minimal or tolerable side effect profile. Figure 78-2 illustrates steps in cancer drug development. Follow­ ing demonstration of antitumor activity in animal models, potentially useful anticancer agents are further evaluated to define an optimal schedule of administration and suitable drug formulation. Safety test­ ing in two animal species on an analogous schedule of administration defines the starting dose for a phase 1 trial in humans, usually but not always in patients with cancer who have exhausted “standard” (already approved) treatments. The initial dose is usually one-sixth to one-tenth of the dose just causing easily reversible toxicity in the more sensitive animal species. If the agent is not intrinsically toxic, doses of drug achieving fractions of the useful plasma concentrations from model systems are studied. Escalating doses of drug are then given during the human phase 1 trial until reversible toxicity is observed or the desired drug concentration is achieved. Dose-limiting toxicity (DLT) defines a dose that conveys greater toxicity than would be acceptable in routine practice, allowing definition of a lower maximum-tolerated dose (MTD). The occurrence of toxicity is, if possible, correlated with plasma drug concentrations. The MTD or a dose just lower than the MTD is usually the dose suitable for phase 2 trials, where a fixed dose and schedule is administered to a relatively homogeneous set of patients with a particular tumor type. If no toxicity has emerged in phase 1 tri­ als, administration of the optimal biologic dose to achieve effective drug concentrations is undertaken. A partial response historically was defined as a decrease of at least 50% in a tumor’s bidimensional area obtained by imaging; more recent response criteria (e.g., Response Evaluation Criteria in Solid Tumors [RECIST]) may use a 30% decrease in aggregate unidimensional areas of target lesions. Response criteria for immunologically directed agents may allow a substantial transient increase in tumor volume as long as a patient’s clinical status is stable, as these agents may evoke inflammatory responses in tumors with subsequent shrinkage or stabilization of lesions. A complete response connotes disappearance of all tumor; progression of disease signifies an increase in size of existing lesions by >25% from baseline or best response or development of new lesions; stable disease fits into none of the above categories. CHAPTER 78 Principles of Cancer Treatment In a phase 3 trial, evidence of improved overall survival or improve­ ment in the time to progression of disease on the part of the new drug is sought in comparison to an appropriate control population. Data from the entire process are the basis for application to a regulatory agency to approve the new agent for commercial marketing. Cancer drug clinical trials conventionally use a toxicity grading scale where grade 1 toxicities do not require treatment, grade 2 toxici­ ties may require symptomatic treatment but are not life-threatening, grade 3 toxicities are potentially life-threatening if untreated, grade 4 toxicities are actually life-threatening, and grade 5 toxicities result in the patient’s death. Active efforts to quantitate effects of anticancer agents on quality of life also frequently occur in early development of oncology drugs. Development of targeted agents may proceed differently. While phase 1–3 trials are still conducted, focus on a particular tumor type even in phase 1 may be enabled by molecular analysis to define target expression in a patient’s tumor necessary for or relevant to the drug’s action. Ideally, pharmacodynamic studies would also assess whether the drug’s target has been affected. The failure of a targeted therapy can Preclinical Model (e.g., mouse or rat) Phase II Untreated Growth delay Tumor size Rx Cytostatic Cytotoxic Time Unique patient number Phase II Unique patient number PART 4 Oncology and Hematology Time Time on Rx FIGURE 78-2  Steps in cancer drug discovery and development. Preclinical activity (top left) in animal models of cancers may be used as evidence to support the entry of the drug candidate into phase 1 trials in humans to define a correct dose and observe any clinical antitumor effect. The drug may then be advanced to phase 2 trials directed against specific cancer types, with rigorous quantitation of antitumor effects. Waterfall plots are a standard representation of how patients’ tumor sizes change in relation to treatment, with predefined cutoffs defining progression of disease (20% increase in size) or partial response (30% decrease in size) serving as benchmarks of potential valuable effect (top right). Swimmer plots (bottom left) allow the delineation of patients with especially long (or short) times on treatment even without response, another basis in the former case for potential perceived clinical benefit of the treatment. Kaplan-Meier plots (bottom right) of survival indices in phase 3 comparative trials may allow definition of superiority, inferiority, or no difference of treatment effect compared to standard or no treatment. be either because the drug missed the target or it hit the target but the target was not central to the tumor’s growth and survival. Within the past decade, agents have been approved for clinical use not in relation to an originating organ site of disease but across all organ types pos­ sessing certain molecular or biologic features. Useful cancer drug treatment strategies using conventional chemo­ therapy agents, targeted agents, hormonal treatments, or biologicals all have one of two valuable outcomes. They can induce cancer cell death, resulting in tumor shrinkage with corresponding clinical ben­ efit evidenced by improvement in patient survival, or increase in time until the disease progresses. Another potential outcome is induction of cancer cell differentiation or dormancy with loss of tumor cell replica­ tive potential and reacquisition of phenotypic properties resembling normal cells. Interaction of a chemotherapeutic drug with its target induces a “cascade” of further signaling steps. These signals ultimately lead to cell death by triggering proteases, nucleases, and endogenous regulators of the cell death pathway (Fig. 78-3) or differentiation by alteration of cancer genome function. Targeted agents differ from chemotherapy agents in that they do not indiscriminately cause macromolecular lesions but regulate the action of specific driver molecules regulating processes considered “hallmarks” of cancer, including unregulated proliferation, physiologic cell death, gene expression, angiogenesis, and escape from immune mechanisms retarding tumor development. Strategies in Systemic Cancer Management  The past 35 years have witnessed a marked evolution in the systemic treatment of cancer not amenable to cure by locally applied treatments. Nonspecific cyto­ toxic agents of limited efficacy for most patients but highly active and curative in a minority disease types have been joined by targeted and biologic therapies. Table 78-3, A lists those tumors considered curable % change tumor % alive (overall survival) or % relapse free Phase III Treatment A Treatment B or no Rx by conventionally available chemotherapeutic agents even when dis­ seminated or metastatic. If a tumor is truly localized to a single site, consideration of surgery or primary radiation therapy should be given as well. Chemotherapy may be used as part of multimodality approaches to offer primary treatment to a clinically localized tumor (Table 78-3, B), interdigitated with radiation and surgery. Chemother­ apy can be administered as an adjuvant, i.e., in addition to surgery or radiation (Table 78-3, C), even after all clinically apparent disease has been removed. This use of chemotherapy has curative potential in, for example, lung, breast, and colorectal neoplasms, as it eliminates micro­ metastatic clinically unapparent tumor. Neoadjuvant chemotherapy refers to administration of chemotherapy before any surgery or radia­ tion to a local tumor in an effort to enhance the effect of subsequent local treatment. Chemotherapy is routinely used in doses that produce reversible acute side effects, primarily consisting of transient myelosuppression with or without gastrointestinal toxicity (usually nausea). “High-dose” chemotherapy regimens can produce markedly increased therapeutic effect, although at the cost of potentially life-threatening complica­ tions that require intensive support, usually in the form of hemato­ poietic stem cell support from the patient (autologous) or from donors matched for histocompatibility loci (allogeneic), or pharmacologic “res­ cue” strategies to block the effect of the high-dose chemotherapy on normal tissues. High-dose regimens have curative potential in defined clinical settings (Table 78-3, D). If cure is not possible, chemotherapy may be undertaken with the goal of palliating the tumor’s effect on the host (Table 78-3, E). In this usage, value is perceived by the demonstration of improved symptom relief, progression-free survival, or overall survival. The best data to support these different therapeutic approaches result from clinical research protocols. In the case of a new drug, these trials might be the Tumor cell growth pathways Tumor cell death pathways Receptor-linked tyrosine kinase inhibitor GDP RAS P P + GTP RAS P13K RAF/MEK inhibitors P RAF Metabolism modulators AKT + MTOR Non receptor linked tyrosine kinase inhibitor MEK Multi kinase inhibitors Cell division Protein synthesis MAP Nuclear export inhibitors DNA digestion Nutrients, O2 Gene products CDK inhibitor Nucleus Autophagy Chromatin epigenetic modulators HR HR RNA Hormone anatgonists Immune cells Transcription factor inhibitors Blood vessels in tumor stroma FIGURE 78-3  Tumor growth and death pathways affected by targeted and cytotoxic agents. After a growth factor binds to its receptor (left side of figure), in the most commonly activated cell proliferation pathway, increased tyrosine kinase activity occurs, either by autophosphorylation of receptor-linked kinases or through recruitment of non-receptor-linked tyrosine kinases, which may also be active constitutively, without requiring a growth factor. This leads to docking of “adaptor” proteins to the phosphorylated tyrosines. One important pathway activated occurs after exchange of GDP for GTP in the RAS family of proto-oncogene products. GTP-RAS activates the RAF kinase, leading to a phosphorylation cascade of MEK and MAP kinases. Mutated KRAS inhibitors have been defined, as well as RAF isoform and MEK inhibitors. The RAF/MEK/MAP kinase pathway ultimately alters gene function to activate cell cycle progression through cyclin-dependent kinases (CDKs). Another route to gene activation utilizes hormone receptors (HRs) interacting with tissue-specific growth regulators such as steroid hormones to alter gene function leading to cell cycle activation. Transcription factors acting at the level of RNA polymerase function at ensembles of gene promoters have proved difficult to target directly, but direct and indirect modulators of transcription factor activity have been defined. Receptor and non-receptor linked tyrosine phosphorylation can lead to activation of phosphatidylinositol3-kinase (PI3K) to produce the phosphorylated lipid phosphatidylinositol-3-phosphate, which activates the AKT kinase to act downstream on the mammalian target of rapamycin kinase (mTOR), directly increasing translation of key mRNAs for gene products regulating cell growth and stimulating cell metabolism by, for example, increasing glucose transporter function. Cytotoxic agents cause cell death (right side of figure) through apoptosis and/or induction of autophagy. Apoptosis is also stimulated by interruption of growth factor (GF) cytokine death signals (e.g., tumor necrosis factor receptor [TNF-R]), which activate “upstream” cysteine aspartyl proteases (caspases) to directly digest cytoplasmic and nuclear proteins, resulting in activation of “downstream” caspases; these activate nucleases to cause DNA fragmentation, a hallmark of apoptosis. Chemotherapy agents that create lesions in DNA or alter mitotic spindle function activate gene function to alter mitochondrial integrity. The antiapoptotic protein BCL2 attenuates mitochondrial toxicity, whereas proapoptotic gene products such as BAX, PUMA, etc., antagonize the action of BCL2. Damaged mitochondria release cytochrome C and apoptosis-activating factor (APAF), which activate caspase 9 to cause DNA fragmentation. In addition, membrane damage with activation of sphingomyelinases results in the production of ceramides that can cause direct damage to mitochondria. Protein translation is followed by a folding process in the Golgi apparatus. Misfolded proteins are processed through the proteasome for protease digestion and recycling of amino acids. Disruption of this process can contribute to autophagy, where the cell starves for critical nutrients, or itself induce apoptosis through a distinct pathway activated by misfolded protein accumulation. Antiangiogenic agents and immune therapies work in the tumor stroma (lower left) on supporting elements including blood vessels and host inflammatory cells. basis for U.S. Food and Drug Administration (FDA) approval for com­ mercial use of the agent. Patients treated with palliative intent should be aware of their diag­ nosis and the limitations of the proposed treatments, have access to supportive care, and have suitable “performance status,” according to assessment algorithms such as the one developed by Karnofsky (see Death signal receptor Apoptosis modulators Membrane damage TNF-R SMase BC12 Ceramide Mitochondrial damage Caspase 8 p53 + + Effector caspases Proapoptotic Gene Expression BAX PUMA NOXA PIGs, etc. + DNA damage or Cytochrome C Caspase 3 APAF Cell targets Caspase 9 Nuclease activation CHAPTER 78 + + Disordered chromosome structure or Cell targets Principles of Cancer Treatment Misfolded proteins Folded proteins Golgi Protein production Proteasome Proteosome inhibitors Peptides Amino acids Table 73-4) or by the Eastern Cooperative Oncology Group (ECOG) (see Table 73-5). ECOG performance status (PS) 0 patients are without symptoms; PS1 patients are ambulatory but restricted in strenuous physical activity; PS2 patients are ambulatory and active 50% or more of the time but unable to work; PS3 patients are capable of limited self-care but are active <50% of the time; and PS4 patients are totally TABLE 78-3  Clinical Impact on Cancers with Cytotoxic Chemotherapy A.  Advanced Cancers with Possible D.  Cancers Possibly Cured with Cure Acute lymphoid and acute myeloid leukemia (pediatric/adult) Hodgkin’s disease (pediatric/adult) Lymphomas—certain types (pediatric/ adult) Germ cell neoplasms   Embryonal carcinoma   Teratocarcinoma   Seminoma or dysgerminoma   Choriocarcinoma Gestational trophoblastic neoplasia Pediatric neoplasms   Wilms’ tumor   Embryonal rhabdomyosarcoma   Ewing’s sarcoma   Peripheral neuroepithelioma   Neuroblastoma Small-cell lung carcinoma Ovarian carcinoma B.  Advanced Cancers Possibly Cured by High-Dose Chemotherapy with Stem Cell Support Relapsed leukemias, lymphoid and myeloid Relapsed lymphomas, Hodgkin’s and non-Hodgkin’s Chronic myeloid leukemia Multiple myeloma E.  Cancers Responsive with Useful Palliation, But Not Cured, by Chemotherapy Bladder carcinoma Chronic myeloid leukemia Hairy cell leukemia Chronic lymphocytic leukemia Lymphoma—certain types Multiple myeloma Gastric carcinoma Cervix carcinoma Endometrial carcinoma Soft tissue sarcoma Head and neck cancer Adrenocortical carcinoma Islet cell neoplasms Breast carcinoma Colorectal carcinoma Glioma Lung cancer   Small-cell   Non-small-cell F.  Tumors Poorly Responsive PART 4 Oncology and Hematology Chemotherapy, Radiation, ± Surgery Squamous carcinoma (head and neck) Squamous carcinoma (anus) Bladder carcinoma Breast carcinoma Carcinoma of the uterine cervix Esophageal carcinoma Non-small-cell lung carcinoma (stage III) Small-cell lung carcinoma C.  Cancers Possibly Cured with in Advanced Stages to Chemotherapy Pancreatic carcinoma Biliary tract neoplasms Thyroid carcinoma Carcinoma of the vulva Prostate carcinoma Melanoma Hepatocellular carcinoma Salivary gland cancer Chemotherapy as Adjuvant to Surgery Breast carcinoma Colorectal carcinomaa Osteogenic sarcoma Soft tissue sarcoma aRectum also receives radiation therapy. confined to bed or chair and incapable of self-care. Only PS0, PS1, and PS2 patients are generally considered suitable for palliative (noncura­ tive) treatment. If there is curative potential, even poor-PS patients may be treated (especially if their symptoms are directly related to a cancer that may respond to treatment), but their prognosis is usually inferior to that of good-PS patients treated with similar regimens. Assessment of physiologic reserve through use of the geriatric assessment tool can be helpful, but no measure of comorbidities or physiologic reserve is considered standard. The turn of the millennium marked the arrival of new strategies for cancer treatment. Prominent among these are cancer biologic therapy, which harnesses the use of immune system–derived reagents or strategies, and cancer targeted therapies, which are directed at specific molecular targets differentially expressed in malignant as opposed to normal tissues. ■ ■CANCER BIOLOGIC THERAPY Figure 78-4 presents the landscape of cancer biologic therapy agents and actions. The goal of biologic therapy is to manipulate the hosttumor interaction in favor of the host, potentially at an optimum biologic dose that might be different than MTD. As a class, biologic therapies may be distinguished from cytotoxic and molecularly tar­ geted agents in that biologic therapies require activity (e.g., antigen expression or internalization) on the part of the tumor cell or on the part of the host (e.g., T-cell engagement or cytokine elaboration) to allow therapeutic effect. Antibody-Mediated Therapeutic Approaches  Figure 78-4 illustrates current antibody-based strategies in cancer treatment. The ability to grow very large quantities of high-affinity monoclonal anti­ bodies directed at specific tumor antigens produced by animals allows the grafting of animal-derived antigen-combining sequences into human immunoglobulin genes (chimerized or humanized products) or derived de novo from mice bearing human immunoglobulin gene loci. Four general strategies have emerged using antibodies. Anti-tumor cell antibodies target tumor cells directly to inhibit intracellular functions or attract immune or stromal cells. Bispecific tumor engaging (BiTe) anti­ bodies directly bind to a tumor cell and to a host immune cell. Immu­ noregulatory antibodies target antigens expressed on host immune cells to boost the host’s immune response to the tumor. Finally, antibody conjugates link the antibody to drugs, toxins, or radioisotopes to target these “warheads” for delivery to the tumor. Stroma-directed antibodies are currently available against tumor-supporting vasculature. ANTI-TUMOR CELL ANTIBODIES (FIG. 78-4)  Humanized antibodies against the CD20 molecule expressed on B-cell lymphomas (rituximab and ofatumumab) are exemplary of antibodies that affect both signal­ ing events driving lymphomagenesis as well as activating immune responses against B-cell neoplasms. They are used as single agents and in combination with chemotherapy and radiation in the treatment of B-cell neoplasms. Obinutuzumab is an antibody with altered glycosyl­ ation that enhances its ability to activate killer cells; it is also directed against CD20 and is of value in chronic lymphocytic leukemia. Unintended side effects of any antibody include infusion-related hypersensitivity reactions, which can be managed with glucocorticoid and/or antihistamine prophylaxis, and prolonged infusion strategies. Anti-B-cell-directed antibodies can have the unintended effect of exacerbating immunosuppression with the emergence of increased opportunistic infections. Reactivation of latent infections may also occur; an assessment of a patient’s hepatitis B and C status is conven­ tionally done before treatment. Concomitant use of antivirals directed against hepatitis may be indicated. Patients with HIV and lymphoma need antivirals optimized to minimize interaction with anti-lymphoma treatments; consultation with infectious disease specialists is war­ ranted. Anti-tumor cell antibodies also include approaches to activate complement and are exemplified by alemtuzumab directed against CD52; it is active in chronic lymphoid leukemia and T-cell malignan­ cies. Tumor lysis syndrome prophylaxis may be warranted. Epidermal growth factor receptor (EGFR)-directed antibodies (e.g., cetuximab and panitumumab) have activity in colorectal cancer refrac­ tory to chemotherapy, particularly when used to augment the activity of an additional chemotherapy program, and in the primary treatment of head and neck cancers treated with radiation therapy. Direct effects on the tumor may mediate an antiproliferative effect as well as stimu­ late the participation of host mechanisms involving immune cell or complement-mediated response to tumor cell–bound antibody. AntiEGFR antibodies can cause an acneiform rash requiring topical antibi­ otic and glucocorticoid cream treatment; photosensitivity also occurs. The HER2/neu receptor overexpressed on epithelial cancers, espe­ cially breast and certain gastrointestinal cancers, was initially targeted by trastuzumab, with activity in potentiating the action of chemo­ therapy in breast cancer as well as evidence of single-agent activity. Trastuzumab appears to interrupt intracellular signals derived from HER2/neu and to stimulate anti-tumor cell immune mechanisms. The anti-HER2 antibody pertuzumab, specifically targeting the domain of HER2/neu responsible for dimerization with other HER2 family members, is more specifically directed against HER2 signaling func­ tion and augments the action of trastuzumab. Both trastuzumab and pertuzumab can damage cardiac function, particularly in patients with prior exposure to anthracyclines, and left ventricular function should be checked before treatment and monitored during treatment. Anti-tumor cell antibody CCRX-4: Mogamulizumab CD19: Tafasitamab CD20: Obinutuzumab, Ofatumummab, Rituximab CD38: Daratumumab, Isatuximab CD52: Alemtuzumab EGFR: Cetuximab, Panitumumab EGFR (exon20insert)/MET: Amivantamab GD2 Ganglioide: Dinutuximab HER2: Pertuzumab, Trastuzumab SLAMF7: Elotuzumab T Effector mechanisms Cells Complement T-Ag T cell Bispecific tumorT cell antibody T-Ag CD3-CD19: Blinatumomab CD3-CD20: Glofitamab, Epcoritamab, Mosunetuzumab CD3-BCMA: Teclistumab CD3-gp100Tcr: Tebentafusp Antigens Antigen presenting cell s AgMHC TcR – CTLA4 PD-L1 – Immune-regulating antibody – Cytotoxic T cell Tumor stroma T-regulatory cells Stroma + CTLA4: Ipilimumab, Tremelimumab LAG-3: Relatimab PD-1: Cemiplimab, Dostarlimab, Nivolumab, Pembrolizumab, Retifanlimab PD-L1: Atezolizumab, Avelumab, Durvalumab Blood vessel in tumor stroma Antistroma antibody VEGF: Bevacizumab VEGFR2: Ramucirumab FIGURE 78-4  Immunologic treatments for cancer. Anti–tumor cell antibodies targeting the indicated antigens (T-Ag) expressed on tumor cells or antibody-derived constructs (upper left) can either directly interfere with tumor cell function by, e.g., inhibiting growth-promoting pathways, or recruit host immune effector cells actively (especially through bispecific tumor-engaging [BiTe] strategies; middle left), Fc receptors, or cytotoxic mechanisms such as complement. Endogenous T cells can be activated by immunomodulatory cell targeting antibodies (lower left). Specifically, tumor cell–derived antigens are taken up by antigen-presenting cells (APCs), also in the stroma. Antigens are processed by the APCs to peptides presented by the major histocompatibility complex (MHC) to T-cell antigen receptors (TcRs), thus providing a positive (+) activation signal for the cytotoxic tumor cells to kill tumor cells bearing that antigen. Negative (–) signals inhibiting cytotoxic T-cell action include the CTLA4 receptor (on T cells), interacting with the B7 family of negative regulatory signals from APCs, and the PD receptor (on T cells), interacting with the PD ligand-1 (PD-L1) (–) signal coming from tumor cells expressing the PD-L1. Strategies that inhibit CTLA4 and PD-1 function are a means of stimulating cytotoxic T-cell activity to kill tumor cells. Lymphocyte activating gene 3 (LAG3) has recently been shown to promote PD axis immunosuppression, and inhibition of that target has shown clinical value. Tumor stroma-directed antibodies cause anti–vascular endothelial cell growth factor (VEGF)–mediated antiangiogenic and tumor interstitial pressure-modulating strategies. Proceeding clockwise in the figure from the upper right, antibody-drug conjugates have recently been designed to deliver cytotoxic drugs, indicated by “T” (upper right). Relatively nonspecific immunomodulators include vaccines instilled directly into the tumor stroma, agents such as the “imids” that alter tumor and stromal cell cytokine production, and cytokines such as interferon or interleukin 2 (IL-2), which can affect tumor-infiltrating lymphocyte function or have direct antitumor effects. Vaccines targeting tumor cell antigens or live attenuated oncolytic viruses injected into tumors can cause tumor cell lysis with induction of a prominent host antitumor immune response to virus antigens and target antigens (T-Ags) (middle right). In the right lower portion of the figure, strategies to deliver activated immune cells include harvest of autologous T cells that are then infected with a lentivirus or other construct that targets antigens (T-Ags) expressed on tumor cells (chimeric antigen receptor [CAR] T cells), with the targeted antigen indicated. The BiTe antibody blinatumomab was constructed to have an antiCD19 antigen-combining site directed at a cancer cell as one valency with an anti-CD3 binding site as the other. This antibody can bring T cells (with their anti-CD3 activity) close to neoplastic B cells bearing the CD19 determinant. Blinatumomab is active in B-cell neoplasms such as acute lymphocytic leukemia. Unique toxicities include cytokine release syndrome (fever, hypotension, tachycardia) and neurologic deterioration manifest initially by deterioration in handwriting accu­ racy, which can proceed to more florid cortical dysfunction, suggesting a need for dose pausing and/or glucocorticoid use. Antibody-drug conjugate See Table 78-6 for: Antibody linked DNA disruptors Antibody linked microtubule agents Antibody linked topo I inhibitors T-Ag Nontargeted/indirect immunomodulator Host cells Tumor cell Bacille Calmette-Guerin (BCG) Glucocorticoids (high-dose) Imids: Lenalidomide, Pomalidomide, Thalidomide CHAPTER 78 T-Ag T-Ag V-ag V-ag Oncolytic or immunomodulating virus to V or T antigens V-ag V-ag Principles of Cancer Treatment V-ag V-ag CART Virus Talimogene laherparepvec Nadofaragene firadenovec CAR-T cellular therapy CD19: Axicabtagene ciloleucel, Brexucabtagene autoleucel, Tisagenlecleucel CD38: Ciltacabtagene autoleucel STROMA-DIRECTED ANTIBODIES (FIG. 78-4)  The anti–vascular endo­ thelial growth factor (VEGF) antibody bevacizumab shows evidence of value in renal cancers, where activation of VEGF signaling occurs as part of disabled hypoxia-induced signaling in the tumor cells. When combined with chemotherapeutic agents, it may increase responses in colorectal and nonsquamous lung cancers. The mechanism for this effect may relate to improved delivery and tumor uptake of the cyto­ toxic, or even immunoregulatory, antibodies used to treat hepatocel­ lular cancer, owing to decreased tumor interstitial pressure. VEGF was originally isolated as a “tumor permeability factor” causing leakiness of tumor blood vessels. When used in gliomas, it may, by decreasing vascular permeability, allow replacement of steroids to decrease intra­ cranial pressure. Bevacizumab has a number of side effects including hypertension, thrombosis, proteinuria, hemorrhage, and gastrointesti­ nal perforations with or without prior surgeries; these adverse events also occur with small-molecule drugs modulating VEGF receptor (VEGFR) function. IMMUNOREGULATORY ANTIBODIES (FIG. 78-4)  Purely immunoregu­ latory antibodies stimulate immune responses to mediate tumordirected cytotoxicity. An understanding of the tumor-host interface has revealed that cytotoxic tumor-directed T cells are frequently inhibited by ligands upregulated in the tumor cells. The programmed death ligand 1 (PD-L1; also known as B7-homolog 1) was initially recognized as inducing T-cell death through a receptor present on T cells, termed the programmed death (PD) receptor, which physiologically regulates the intensity of the immune response to any antigen. The PD family of ligands and receptors also regulates macrophage function, present in tumor stroma. These actions raised the hypothesis that antibodies directed against the PD signaling axis (both anti-PD-L1 and anti-PD) might be useful in cancer treatment by allowing reactivation of the immune response against tumors. Ipilimumab, an antibody directed against the anti-CTLA4 (cytotoxic T lymphocyte antigen 4), which is expressed on T cells (not tumor cells), responds to signals from antigen-presenting cells (Fig. 78-4) and also downregulates the intensity of the T-cell proliferative response to antigens derived from tumor cells. Indeed, manipulation of the CTLA4 axis was the first demonstration that purely immunoregulatory anti­ body strategies directed at T-cell physiology could be safe and effec­ tive in the treatment of cancer. Ipilimumab, alone or in combination with PD-1-directed antibodies, is approved for treatment of metastatic melanoma and lung cancers. PART 4 Oncology and Hematology Nivolumab, directed against the PD-1 receptor, and atezolizumab (anti-PD-L1) are exemplary of anti-PD-1-directed immunoregula­ tory antibodies, with clinical benefits in many cancers (Table 78-4). Pembrolizumab is approved for first-line treatment of metastatic non-small-cell lung cancer tumors that express the PD-L1 ligand. This development was a milestone in cancer therapeutics, replacing chemotherapy in this patient subset. Lymphocyte activation gene 3 (LAG3) binds to major histocompatibility complex (MHC) on antigen-presenting cells to augment the effect of the PD-1 and CTLA4 pathways. Relatlimab is a first-in-class inhibitor of LAG3 action and augments the effect of nivolumab in melanoma. Importantly, the clinical observation that tumors most amenable to treatment with immunoregulatory antibodies were in sites (lung, skin, genitourinary) exposed to environmental carcinogens or occurred in patients with known mutations in DNA repair pathways stimulated specific research as to whether the “mutational burden” of tumors could predict value from anti-PD strategies. Results to date in general support this hypothesis and led to the first regulatory approvals for immunomodulating antibodies in a “tissue agnostic” fashion. Specifi­ cally, detection of deficiencies in a tumor DNA mismatch repair system or with evidence of increased tumor mutation burden is a specific indication for use of certain immunoregulatory agents, irrespective of the disease site of origin. The increased efficacy in the setting of higher tumor mutational burden is thought to be due to the presence of more proteins in the tumor structurally altered by mutation that can be rec­ ognized as foreign by the immune system. Prominent autoimmune hepatic, cardiac, endocrine, cutaneous, neurologic, and gastrointestinal adverse events can occur with the use of ipilimumab as well as the PD-1-directed antibodies. Emergency use of glucocorticoids may be required to attenuate severe toxicities. Although theoretically such glucocorticoid use can attenuate the antitumor effect, response rates do not appear to be compromised by their use to abrogate serious organ toxicity attributable to use of immunomodulatory antibodies. Importantly for the general internist, immunologic toxicities can occur late after exposure to the modulators of PD and CTLA4 action, even while the patient may have sustained control of tumor growth. TABLE 78-4  Clinical Impact of Host T Lymphocyte–Modified Cellsa or Host T Lymphocyte–Directed Immunoregulatory Antibodiesc A.  Advanced Cancers with Positive Effect (at least 25% of treated patients have stable disease or progression-free survival of ≥27 weeks or better) or Frequent or Unexpected Prolonged Responders (efficacy may be limited to CD expression–dependent or PD-1 ligand–expressing subtypes) Acute lymphoid leukemiab Adrenocortical carcinomac Breast cancer, hormone receptor negative, HER2 negative (with chemotherapy)c Colorectal cancer (microsatellite instability-high [MSI-H] or mismatch repair deficient, usually with fluoropyrimidine, oxaliplatin, or irinotecan)c Cervix, squamous carcinomac Cutaneous, squamous carcinomac Diffuse large B-cell non-Hodgkin’s lymphoma, not otherwise specifieda Diffuse large B-cell non-Hodgkin’s lymphoma, primary mediastinal subtypeb Endometrial carcinoma (with lenvatinib, if microsatellite instability-stable [MSI-S] or mismatch repair wild-type)c Esophageal squamous carcinomac Gastric/gastroesophageal adenocarcinomac Head and neck squamous carcinomac Hepatocellular cancer (after sorafenib)c Hodgkin’s diseasec Mantle cell lymphomaa Melanomac Merkel cell carcinomac Mesotheliomac MSI-H or mismatch repair–deficient solid tumors without satisfactory alternativec Mycosis fungoidesc Multiple myelomaa Non-small-cell lung carcinomac Paraganglioma/pheochromocytomac Renal cell carcinomac Sarcoma, alveolar soft partc Small-cell lung carcinomac Solid tumors with high tumor mutational burden (TMB) (≥10 mutations/ megabase) that have progressed following prior therapy without satisfactory alternative treatmentc Urothelial carcinomac (including bladder, ureter) B.  Advanced Cancers with Insufficient Data to Support Host-Derived T Lymphocyte or Immunoregulatory Antibody Treatmentd Acute myeloid leukemia Anus, squamous carcinoma Breast cancer, hormone receptor positive Breast cancer, hormone receptor negative, HER2 positive Biliary tract cancers (if MSI-S or mismatch repair wild-type) Chronic lymphocytic leukemia Chronic myeloid leukemia Gastrointestinal neuroendocrine/islet cell carcinoma Glioma, all grades including glioblastoma Germ cell neoplasms Ovarian cancer Osteogenic sarcoma Pancreas adenocarcinoma Pediatric tumors (Wilms’, rhabdomyosarcoma, Ewing’s, neuroblastoma, osteosarcoma) Prostate adenocarcinoma Salivary gland carcinoma Soft tissue sarcoma (except alveolar soft part) T-cell non-Hodgkin’s lymphoma (except mycosis fungoides) Vulva, squamous carcinoma aChimeric antigen receptor (CAR)-modified autologous T cells in relapsed or refractory cases. bBoth CAR-modified autologous T cells or an immunoregulatory antibody. cT-cell-directed immunoregulatory antibody strategies including anti-PD-1 and/or anti-PD-L1 antibodies or bispecific tumor engaging (BiTe) antibodies against a particular tumor cell antigen. dUnless MSI-high, mismatch repair deficient, or TMB ≥10 mutations/megabase. Nontargeted Immunomodulators (Fig. 78-4)  Bacille Calmette-Guérin, a killed mycobacterial product, invokes a useful immune response when instilled locally into the bladder in the setting of preinvasive bladder cancers. The “imids” thalidomide, lenalidomide, and pomalidomide alter cytokine elaboration in the tumor microen­ vironment and have antiangiogenic actions. They are a cornerstone in the management of multiple myeloma. Thromboses (warranting consideration of prophylactic anticoagulation), gastrointestinal and neuropathic adverse events, and prominent teratogenicity can occur as a consequence of their use. “High-dose” glucocorticoids stimulate apoptosis in normal and neoplastic lymphoid cells and are a mainstay in the treatment of lymphoid leukemias, lymphomas, and plasma cell neoplasms. Cytokines  Only interferon α (IFN-α) and interleukin 2 (IL-2) are considered for current treatment indications. IFN is not curative for any tumor but can induce partial responses in follicular lymphoma, hairy cell leukemia, chronic myeloid leukemia, melanoma, and Kaposi’s sarcoma. It produces fever, fatigue, a flulike syndrome, malaise, myelosuppression, and depression and can induce clinically significant autoimmune disease. IL-2 exerts its antitumor effects indirectly through augmentation of immune function. Its biologic activity is to promote the growth and activity of T cells and natural killer (NK) cells. High doses of IL-2 can produce tumor regression in certain patients with metastatic mela­ noma and renal cell cancer. About 2–5% of patients may experience complete remissions that are durable. Patients may require blood pres­ sure support and intensive care to manage the toxicity. However, once the agent is stopped, most of the toxicities reverse completely within 3–6 days. Use of “high-dose” IL-2 regimens has been superseded by immunoregulatory antibodies. Efforts to develop new IL-2-based strat­ egies with less toxicity and improved efficacy are continuing. T Cell–Mediated Therapies  Three types of currently used cancer treatments take advantage of the ability of T cells to kill tumor cells. 1. Transfer of allogeneic T cells. This occurs in three major settings: in allogeneic bone marrow transplantation; as purified lymphocyte transfusions following bone marrow recovery after allogeneic bone marrow transplantation; and as pure lymphocyte transfusions fol­ lowing immunosuppressive (nonmyeloablative) therapy (also called reduced-intensity or minitransplants). In each of these settings, the effector cells are donor T cells that recognize the tumor as being foreign, probably through minor histocompatibility differences. The main risk of such therapy is the development of graft-versushost disease because of the minimal difference between the cancer and the normal host cells. This approach has been useful in certain hematologic cancers refractory to chemotherapeutic strategies. 2. Transfer of autologous T cells. In this approach, the patient’s own T cells are removed from the tumor-bearing host, manipulated in several ways in vitro, and given back to the patient. Tumor antigen– specific T cells can be developed after retroviral transduction of the desired T-cell antigen receptor and expanded to large numbers over many weeks ex vivo before administration. These chimeric antigen receptor (CAR) T cells (Fig. 78-4) have evidence of sustained value in patients with refractory hematopoietic neoplasms such as diffuse large B-cell lymphoma, multiple myeloma, and mantle cell lym­ phoma. Prominent adverse effects include cytokine release syndrome (fever, tachycardia, hypotension) and neurologic manifestations. Clinical investigations are seeking to develop solid-tumor antigendirected CAR strategies, as well as to utilize different immune cell populations such as NK cells to cause useful antitumor activity in ways that may allow “off-the-shelf” products not requiring manipu­ lation and purification of patients’ autologous cells. 3. Tumor vaccines aimed at boosting T-cell immunity. Two types of vaccine approaches are currently approved. Purified autologous antigen-presenting cells can be pulsed with tumor, its membranes, or particular tumor antigens and delivered as a vaccine. Vaccine adjuvants such as granulocyte-macrophage colony-stimulating factor (GM-CSF) may be co-administered. One such vaccine, sipuleucel-T, is approved for use in patients with asymptomatic or minimally symptomatic metastatic hormone-independent prostate cancer. In this approach, the patient undergoes leukapheresis, wherein mono­ nuclear cells (that include antigen-presenting cells) are removed from the patient’s blood. The cells are pulsed in a laboratory with an antigenic fusion protein comprising a protein frequently expressed by prostate cancer cells, prostate acid phosphatase, fused to GMCSF, and matured to increase their capacity to present the antigen to immune effector cells. The cells are then returned to the patient in a well-tolerated treatment. Although no objective tumor response was documented in clinical trials, median survival was increased by about 4 months.   Another important vaccine strategy is directed at infectious agents whose action ultimately is tied to the development of human cancer. Hepatitis B vaccine in an epidemiologic sense prevents hepatocellular carcinoma, and a tetravalent human papillomavirus vaccine prevents infection by virus types currently accounting for 70% of cervical cancer. Unfortunately, these vaccines are ineffective at treating patients who have developed a virus-induced cancer. Oncolytic or Immunomodulating Viruses (Fig. 78-4)  Labo­ ratory studies in animals have utilized viruses to destroy tumors because tumor cells lack endogenous host mechanisms, e.g., IFN elaboration or recognition strategies of viral nucleic acids, that limit virus spread. Viral infection of tumors also can stimulate a prominent host response to viral and tumor cell antigens, leading to immune effects against local tumor cells. Talimogene laherparepvec is a clinically approved attenuated herpes virus that acts to stimulate immune responses when instilled locally into melanoma deposits. Systemic effects are minimal in this application. This general strategy is being considered particularly in tumors not amenable to useful effects of currently approved immu­ noregulatory antibodies or in conjunction with immunoregulatory anti­ bodies. Nadofaragene firadenovec is an adenovirus construct instilled into the bladder; it is nonreplicating but can infect urothelial cells to deliver a gene resulting in consistently produced IFN-α2b, which has a local antitumor effect. It is useful in the treatment of superficial bladder cancers. It is not established whether infection of tumor cells, normal urothelial cells, or both contribute to the antitumor effect. CHAPTER 78 Principles of Cancer Treatment ■ ■CANCER CYTOTOXIC THERAPY Table 78-5 lists commonly used cytotoxic cancer chemotherapy agents and pertinent clinical aspects of their use, with particular reference to adverse effects that might be encountered by the generalist in the care of patients. The drugs were initially discovered through screening of chemicals and natural product extracts for evidence of antitumor activity in animals or were designed with knowledge of biochemi­ cal pathways affecting nucleic acid synthesis. They may be usefully grouped into two general categories: those affecting DNA and those affecting microtubules. As illustrated in Fig. 78-3, disruption of DNA or microtubule integ­ rity is a major trigger of cellular apoptosis pathways. An additional factor in drug effect stems from recent observations that tumor cells have increased tolerance of specific types of DNA damage owing to defects in DNA repair pathways. This state is thought to facilitate the survival of the neoplastic clone as it experiences DNA mutations dur­ ing the course of carcinogenesis. DNA-directed cytotoxic agents can create lesions in DNA that are poorly tolerated by cells with neoplasmpromoting DNA repair pathway mutations. This results in a “synthetic lethal” interaction of the drug with cells bearing the DNA repair path­ way mutation. Examples of a potential “synthetic lethal effect” will be pointed out in relation to clinical applications below. DNA-Interactive Agents  DNA replication occurs during the syn­ thesis or S-phase of the cell cycle, with chromosome segregation of the replicated DNA in the M, or mitosis, phase. The G1 and G2 “gap phases” precede S and M, respectively. Chemotherapeutic agents have been divided into “phase-nonspecific” agents, which can act in any phase of the cell cycle, and “phase-specific” agents, which require the cell to be at a particular cell cycle phase to cause greatest effect. TABLE 78-5  Commonly Used Cytotoxic Chemotherapy Agents DRUG ADVERSE EVENTS NOTES Direct DNA-Interacting Agentsa   Alkylator or platinating drug   Bendamustine Vehicle allergy, My, Der, ↑LFTs TLS, Ves, IR, DA-R, DA-H Carboplatin My, N, V, R Dose according to CrCl: to AUC of 5–7 mg/mL per min [AUC = dose/(CrCl + 25)] Chlorambucil Common alkylator   Cisplatin N, V, Neu, My, R, Ototoxic, ↓K+, ↓Mg2+, ↓Ca2+ Osmotic diuresis, N, V prophylaxis, DA-R Cyclophosphamide Common alkylator, cystitis, cardiac (high dose) Liver required to activate, DA-R, DA-H, hydration ± mesna protects bladder Dacarbazine (DTIC) Common alkylator, Ves DA-R Ifosfamide My, common alkylator, bladder, CNS DA-R, must use concomitant mesna Lomustine (CCNU) Common alkylator but My, has delayed nadir, ↑LFTs Plm ± fibrosis: PFTs prior to treatment and repeat frequently; cease if fibrosis occurs Lurbinectedin My, ↑LFTs, N, V CYP3A4 Melphalan Common alkylator but My, has delayed nadir DA-R Oxaliplatin N, V, My, Neu Reversible laryngopharyngeal spasm risk Procarbazine Common alkylator, CNS Disulfiram-like effect with alcohol, MAOI, like HBP after tyramine-rich foods Temozolomide Common alkylator but My, has delayed nadir Pneumocystis prophylaxis Antitumor antibiotics and topoisomerase poisons   Bleomycin Plm (↑FIO2 worsen), Der, Raynaud’s, IR* Monitor DLCO before/during treatment, DA-R PART 4 Oncology and Hematology Dactinomycin My, N, V, mucositis, Ves, alopecia Radiation recall Doxorubicin, daunorubicin, epirubicin, idarubicin TOPOII; My, mucositis, alopecia, ↓LVEF acute/chronic, Ves Co-administration with heparin aggregate, secondary leukemia, DA-H, radiation recall Doxorubicin, liposomal TOPOII; My, ↓LVEF, IR*, PPED DA-H, radiation recall Etoposide TOPOII; My, alopecia, IR with rapid IV, N, V, mucositis DA-H, DA-R Irinotecan TOPOI; My, D: “early onset” with cramping, flushing, vomiting: treat with atropine; “late onset” after several doses: use loperamide 4 mg with first stool then 2 mg q2h until 12 h without stool up to 16 mg/24 h; My dependent on UGT1A1 phenotype, R, ILD Irinotecan, liposomal TOPOI; My, D (administer loperamide for D of any severity), IR*, ILD Mitoxantrone TOPOII; Ves, blue urine, nails, and sclerae Interacts with heparin; DA-H, alopecia, N, V, radiation recall Topotecan TOPOI; My, mucositis, N, V, alopecia DA-R, rare ILD Indirectly DNA-Interacting Agents Pyrimidine analogues   Capecitabine My, D, PPED, cardiac adverse events, R, Der Oral prodrug of 5-FU Cytarabine (cytosine arabinoside [ara-C]) My, mucositis, CNS (high dose), conjunctivitis (high dose; use steroid eyedrops until 72 h after last dose), noncardiogenic pulmonary edema 5-Fluorouracil (5-FU) My, D, mucositis, CNS, Der, cardiac adverse events, PPED Toxicity enhanced by leucovorin by increasing “ternary complex” with thymidylate synthase; metabolism in tissue; dihydropyrimidine dehydrogenase deficiency increases toxicity; enhances warfarin effect Gemcitabine My, N, V, ↑LFT, fever/”flu syndrome” Rare ARDS; rare HUS, rare PRES, radiosensitization with long infusion Trifluridine/tipiracil My, mucositis, N, V, unusual PPED Trifluridine directly inhibits thymidylate synthase and is incorporated into DNA; tipiracil inhibits thymidine phosphorylase, which degrades trifluridine Purine analogues     Fludarabine phosphate My, mucositis, CNS, Der Converted to F-ara ATP in cells by deoxycytidine kinase; DA-R 6-Mercaptopurine (6-MP), 6-thioguanine (6-TG) Mv, N, ↑LFT 6-MP metabolized by xanthine oxidase, decrease dose with allopurinol; 6-MP and 6-TG increased toxicity with thiopurine methyltransferase deficiency Antifolates   Methotrexate My, ↑LFT with fibrosis with chronic use, Plm, R, mucositis Toxicity lessened by leucovorin, bypassing block of dihydrofolate reductase, excreted in urine; DA-R or hold; NSAIDs increase renal toxicity; sequestered in third space fluids Pemetrexed My Supplement folate/B12, omit for CrCl <45 mL/min Miscellaneous Antimetabolite-Like Agents   Asparaginase Thrombosis by decrease of antithrombin IIII, but ↓fibrinogen can cause hemorrhage; ↑glucose; ↓albumin, hypersensitivity; CNS; pancreatitis; ↑LFTs Hydroxyurea My, N, mucositis, rare ↓CrCl DA-R, augments antimetabolite effect Prodrug requires metabolism to active drug SN-38, which is cleared by UGT1A1 with degree of My dependent on patient UGT1A1 genotype, DA-H Consider guide dosing by UGT1A1 genotype testing, CYP3A4; NO recommended dose for T Bili >ULN Metabolized in tissues by deamination but renal excretion prominent at doses >500 mg; therefore, DA-R in “high-dose” regimens Decrease protein synthesis; indirect inhibition of DNA synthesis by decreased histone synthesis; blocks methotrexate action (Continued) (Continued) TABLE 78-5  Commonly Used Cytotoxic Chemotherapy Agents DRUG ADVERSE EVENTS NOTES Antimitotic agents   Docetaxel IR*, VLS, My, ↑LFTs, Der, Neu, stomatitis, alopecia, N, V, D Premedicate with steroids, H1 and H2 blockers; DA-H; monitor for second primary malignancies; alcohol in vehicle Eribulin My, Neu, ↑QT DA-H, DA-R Ixabepilone My, Neu, IR*, N, V, D, alopecia Premedicate with steroids, H1 and H2 blockers; CYP3A4, DA-H Nab-paclitaxel My, Neu, Ves DA-H, CYP3A4, CYP2C8 Paclitaxel IR*, My, alopecia, N, V, D, mucositis, Neu, Ves Premedicate with steroids, H1 and H2 blockers; DA-H, CYP3A4, CYP2C8, alcohol in vehicle Vinblastine My, Ves, Neu, HBP, Raynaud’s, Ves, ↑LFTs, ileus/ constipation (use prophylactic stool softeners) Vincristine Ves, Neu, SIADH, ileus/constipation (use prophylactic stool softeners) Vinorelbine My, Ves, allergic bronchospasm (immediate), dyspnea/ cough (subacute) Note: Data abstracted in part from publicly available U.S. Food and Drug Administration label. All agents in this class have the potential for prominent embryofetal toxicity; use without contraception by female patients of childbearing potential is not recommended. Effective contraception for female partners who are of childbearing potential of patients undergoing treatment should also be considered; use during lactation is also not recommended; all DNA interacting agents have theoretical risk of late secondary neoplasms, particularly where noted. Indications and events of prominent general medical importance include the following: ARDS, acute respiratory distress syndrome; AUC, area under concentration-time curve; Common alkylator toxicities: N, V, My, alopecia, mucositis, ↓fertility, cumulative lung toxicity; CNS, central nervous system (can include altered sensorium, cortical and cerebellar signs, dysarthria, altered seizure threshold); Cor, corneal keratopathy, consider pretreatment ophthalmologic exam with prophylactic lubricating eyedrops ± ocular steroids; CrCl, creatinine clearance; CYP___, interaction with drugs metabolized by the indicated cytochrome(s) P450; DA-H, dose adjust for hepatic dysfunction; DA-R, dose adjust for renal dysfunction; Der, dermatologic toxicity; HBP, high blood pressure; HUS, hemolytic-uremic syndrome; ILD, interstitial lung disease; IR, infusion reaction; IR*, infusion reaction prophylaxis specifically recommended; LFT, liver function tests; ↓LVEF, left ventricular ejection fraction, monitor echocardiogram; My, anemia, decrease in white blood cells, platelets, with risk of neutropenic fever, hemorrhage, therefore dose reduce or hold dose for decreased neutrophil or platelet counts unless marrow infiltrated by drug-responsive tumor; N, nausea; Neu, peripheral neuropathy; Plm, pulmonary; PPED, palmar-plantar erythrodysesthesia (i.e., hand-foot syndrome); PRES, posterior reversible leukoencephalopathy syndrome; PT, prothrombin time; PTT, partial thromboplastin time; ↑QT, pre- and intratreatment electrocardiogram monitoring, normalize K+, Mg2+, ionized Ca2+; R, renal injury possible; SIADH, syndrome of inappropriate antidiuretic hormone; TLS, risk of tumor lysis syndrome if brisk response; TOPO___, agent targets the indicated topoisomerase; UGT___, metabolism by UDP-glucuronosyltransferase of the indicated genotype; Ves, extravasation injury possible; V, vomiting; VLS, vascular leak syndrome; VOD, veno-occlusive liver disease. Alkylating agents (Table 78-5) as a class are cell cycle phase–nonspecific agents. They break down, either spontaneously or after normal organ or tumor cell metabolism, to reactive intermediates that covalently modify bases in DNA. This leads to cross-linkage of DNA strands or the appearance of breaks in DNA as a result of repair efforts. Damaged DNA cannot complete normal cell division; in addition, it activates apoptosis. Alkylating agents share common toxicities: myelosuppres­ sion, alopecia, gonadal dysfunction, mucositis, and pulmonary fibrosis. They also share the capacity to cause “second” neoplasms, particularly leukemia, years after use, particularly when used in low doses for pro­ tracted periods. Cyclophosphamide is inactive unless metabolized by the liver to 4-hydroxy-cyclophosphamide, which decomposes into an alkylating species, as well as to chloroacetaldehyde and acrolein. The latter causes chemical cystitis; therefore, excellent hydration must be maintained while using cyclophosphamide. If severe, the cystitis may be attenu­ ated or prevented altogether (if expected from the dose of cyclophos­ phamide to be used) by mesna (2-mercaptoethanesulfonate). Liver disease impairs cyclophosphamide activation. Sporadic interstitial pneumonitis leading to pulmonary fibrosis can accompany the use of cyclophosphamide, and high doses used in conditioning regimens for bone marrow transplant can cause cardiac dysfunction. Ifosfamide is a cyclophosphamide analogue also activated in the liver, but more slowly, and it requires co-administration of mesna to prevent bladder injury. CNS effects, including somnolence, confusion, and psychosis, can fol­ low ifosfamide use; the incidence appears related to low body surface area or decreased creatinine clearance. Several alkylating agents are less commonly used. Bendamustine has activity in chronic lymphocytic leukemia and certain lymphomas. It is used in transplant preparation regimens. Melphalan shows variable oral bioavailability and undergoes extensive binding to albumin and α1-acidic glycoprotein. Mucositis appears more prominently; however, it has prominent activity in multiple myeloma. Nitrosoureas break down to carbamylating species that not only cause a distinct pattern of DNA base pair–directed reactivity but also can covalently modify proteins. Lomustine is used to treat brain tumors but causes delayed myelotoxicity and can cause lung injury. Procarbazine is metabolized DA-H, unusual; Plm, CYP3A4 DA-H, CYP3A4; less My than with vinblastine; unusual Plm DA-H; less neurotoxic than other vincas CHAPTER 78 Principles of Cancer Treatment in the liver and possibly in tumor cells to yield a variety of free radical and alkylating species. In addition to myelosuppression, it causes hyp­ notic and other CNS effects, including vivid nightmares. It can cause a disulfiram-like syndrome on ingestion of ethanol. Both procarbazine and lomustine are used in the treatment of brain tumors. Dacarbazine (DTIC) is activated in the liver to yield the highly reactive methyl diazo­ nium cation. It causes only modest myelosuppression 21–25 days after a dose but causes prominent nausea on day 1. It is an important com­ ponent of treatment regimens for Hodgkin’s lymphoma and sarcomas. Temozolomide is structurally related to DTIC but is activated by non­ enzymatic hydrolysis in tumors and is bioavailable orally. Brain tumors with alkylguanine alkyl transferase deficiency are selectively susceptible to temozolomide, which alkylates the O6 position of guanine. Cisplatin was discovered fortuitously by observing that bacteria present in electrolysis solutions with platinum electrodes could not divide. Only the cis diamine configuration is active as an antitumor agent. In tumor cells, a chloride is lost from each position. The result­ ing positively charged species is an efficient DNA interactor, forming Pt-based cross-links. Therefore “platinating agents” are considered with alkylating agents as forming related lesions in DNA. Cisplatin is administered with abundant hydration, including forced diuresis with mannitol to prevent kidney damage; even with the use of hydra­ tion, gradual decrease in kidney function is common, along with noteworthy anemia. Hypomagnesemia frequently attends cisplatin use and can lead to hypocalcemia and tetany. Other common toxicities include neurotoxicity with stocking-and-glove sensorimotor neuropa­ thy. Hearing loss occurs in 50% of patients treated with conventional doses. Cisplatin is intensely emetogenic, requiring prophylactic anti­ emetics. Myelosuppression is less evident than with other alkylating agents. Chronic vascular toxicity (Raynaud’s phenomenon, coronary artery disease) is a more unusual toxicity. Carboplatin displays less nephro-, oto-, and neurotoxicity. However, myelosuppression is more frequent, and because the drug is exclusively cleared through the kid­ ney, adjustment of dose for creatinine clearance must be accomplished through use of various dosing nomograms. Oxaliplatin is a platinum analogue with noteworthy activity in colon cancers refractory to other treatments. It is prominently neurotoxic. Lurbinectedin binds to DNA through the “DNA minor groove” with covalent interaction with the N2 position of certain guanines. Transient altered liver function can occur, as well as cytopenias. Lurbi­ nectedin has activity in small-cell lung cancer. The first example of this agent class, trabectedin, requires a prolonged infusion schedule but is active in certain sarcomas, in part due to its modulation of transcrip­ tion factor function. Antitumor Antibiotics and Topoisomerase Poisons  Anti­ tumor antibiotics are substances produced by bacteria that provide a chemical defense against hostile microorganisms. They bind to DNA directly and can frequently undergo electron transfer reactions to gen­ erate free radicals in close proximity to DNA, leading to DNA damage in the form of single-strand breaks or cross-links. Topoisomerase poi­ sons include natural products or semisynthetic derivatives that modify enzymes that allow DNA to unwind during replication or transcription. These include topoisomerase I, which creates single-strand breaks that then rejoin following the passage of the other DNA strand through the break. Topoisomerase II creates double-strand breaks through which another segment of DNA duplex passes before rejoining. Owing to the role of topoisomerase I in the replication fork, topoisomerase I poisons cause lethality if the topoisomerase I–induced lesions occur in S-phase. Doxorubicin intercalates into DNA, thereby altering DNA structure, replication, and topoisomerase II function. It can also undergo reduc­ tion of its quinone ring system, with reoxidation to form reactive oxy­ gen radicals. It causes predictable myelosuppression, alopecia, nausea, and mucositis. In addition, it can cause acute cardiotoxicity in the form of atrial and ventricular dysrhythmias, but these are rarely of clinical significance. In contrast, cumulative doses >550 mg/m2 are associated with a 10% incidence of chronic cardiomyopathy. The incidence of cardiomyopathy appears to be related to peak serum concentration, with low-dose, frequent treatment or continuous infusions better toler­ ated than intermittent higher-dose exposures. Cardiotoxicity has been related to iron-catalyzed oxidation and reduction of doxorubicin in the heart. Dexrazoxane is an intracellular chelating agent that can act as a cardio-protectant. Doxorubicin’s cardiotoxicity is increased when given together with trastuzumab, the anti-HER2/neu antibody. Radia­ tion recall or interaction with concomitantly administered radiation to cause local site complications is frequent. The drug is a powerful vesicant, with necrosis of tissue apparent 4–7 days after an extravasa­ tion; therefore, it should be administered into a rapidly flowing intra­ venous line. Dexrazoxane also can mitigate doxorubicin extravasation. Doxorubicin is metabolized by the liver, so doses must be reduced by 50–75% in the presence of liver dysfunction. Daunorubicin is closely related to doxorubicin and is preferable to doxorubicin owing to less mucositis and colonic damage with frequent high doses used in the curative treatment of leukemia. Idarubicin is also used in leukemia treatment and may have somewhat less cardiotoxicity. Encapsulation of daunorubicin into a liposomal formulation has attenuated cardiac toxicity with antitumor activity in Kaposi’s sarcoma, other sarcomas, multiple myeloma, and ovarian cancer. PART 4 Oncology and Hematology Mitoxantrone is a synthetic topoisomerase II–directed agent with a mechanism similar to the anthracyclines, with less but not absent cardiotoxicity, comparing the ratio of cardiotoxic to effective doses; it is still associated with a 10% incidence of cardiotoxicity at cumulative doses of >150 mg/m2. Etoposide binds directly to topoisomerase II and DNA in a reversible ternary complex. It stabilizes the covalent inter­ mediate in the enzyme’s action where the enzyme is covalently linked to DNA. Prominent clinical effects include myelosuppression, nausea, and transient hypotension related to the speed of administration of the agent. Etoposide is a mild vesicant but is relatively free from other large-organ toxicities. Camptothecins target topoisomerase I. Topotecan is a camptoth­ ecin derivative approved for use in gynecologic tumors and small-cell lung cancer. Toxicity is limited to myelosuppression and mucositis. Irinotecan is a camptothecin with evidence of activity in colorectal carcinoma. Irinotecan is a prodrug, metabolized in the liver to SN-38, its active metabolite. Levels of SN-38 are particularly high in the set­ ting of Gilbert’s disease, characterized by defective uridine diphosphate glucuronosyl transferase (UGT) 1A1 and indirect hyperbilirubinemia, a condition that affects ~10% of the white population in the United States. In addition, irinotecan’s myelosuppression is clearly influenced by the patient’s genotype for UGT1As. Irinotecan causes a delayed (48–72 h) secretory diarrhea related to the toxicity of SN-38. The diar­ rhea can be treated effectively with loperamide or octreotide; immedi­ ate diarrhea when it occurs is responsive to atropine. Bleomycin remains an important component of curative regimens for Hodgkin’s lymphoma and germ cell neoplasms. It forms complexes with Fe2+ while also bound to DNA. Oxidation of Fe2+ gives rise to superoxide and hydroxyl radicals, causing DNA damage. The drug causes little, if any, myelosuppression. Bleomycin is cleared rapidly, but augmented skin and pulmonary toxicity in the presence of renal failure necessitates dose reduction in renal failure. Bleomycin is not a vesicant and can be administered intravenously, intramuscularly, or subcutane­ ously. Common side effects include fever and chills, facial flush, and Raynaud’s phenomenon. The most feared complication of bleomycin treatment is pulmonary fibrosis, which increases in incidence at >300 cumulative units administered and is minimally responsive to treat­ ment (e.g., glucocorticoids). The earliest indicator of an adverse effect is usually a decline in the carbon monoxide diffusing capacity (DLCO) or coughing, although cessation of drug immediately upon docu­ mentation of a decrease in DLCO may not prevent further decline in pulmonary function. Bleomycin is inactivated by a bleomycin hydro­ lase, which is poorly expressed in skin and lung. Because bleomycindependent electron transport is dependent on O2, bleomycin toxicity may become apparent after exposure to transient very high fraction of inspired oxygen (FIO2) even late after treatment. Thus, during surgi­ cal procedures, patients with prior exposure to bleomycin should be maintained on the lowest FIO2 consistent with maintaining adequate tissue oxygenation. Dactinomycin interacts directly with DNA to inhibit RNA tran­ scription. It is important in the curative treatment of pediatric neoplasms, some of which also occur in young adults. Prominent myelosuppression, mucositis, alopecia, radiation recall, and nausea require management. Antimetabolites  A broad definition of antimetabolites would include compounds that interfere with purine or pyrimidine synthesis. Some antimetabolites also cause DNA damage indirectly, through misincorporation into DNA. They tend to convey greatest toxicity to cells in S-phase, and the degree of toxicity increases with duration of exposure. Common toxic manifestations include stomatitis, diarrhea, and myelosuppression. Methotrexate inhibits dihydrofolate reductase, which regenerates reduced folates from the oxidized folates produced when thymi­ dine monophosphate is formed from deoxyuridine monophosphate. Without reduced folates, cells die a “thymine-less” death. N5-Tet­ rahydrofolate or N5-formyltetrahydrofolate (leucovorin) can bypass this block and rescue cells from methotrexate, which is retained in cells by polyglutamylation. Methotrexate is transported into cells by a membrane carrier, and high concentrations of drug can bypass this carrier and allow diffusion of drug directly into cells. These properties have suggested the design of “high-dose” methotrexate regimens with leucovorin rescue of normal marrow and mucosa as part of curative approaches to osteosarcoma in the adjuvant setting and hematopoi­ etic neoplasms of children and adults. Methotrexate is cleared by the kidney via both glomerular filtration and tubular secretion, and toxic­ ity is augmented by renal dysfunction and drugs such as salicylates, probenecid, and nonsteroidal anti-inflammatory agents that undergo tubular secretion. With normal renal function, 15 mg/m2 leucovorin will rescue 10−8–10−6 M methotrexate in 3–4 doses. However, with decreased creatinine clearance, doses of 50–100 mg/m2 are continued until methotrexate levels are <5 × 10−8 M. In addition to bone mar­ row suppression and mucosal irritation, methotrexate can cause renal failure itself at high doses owing to crystallization in renal tubules; therefore, high-dose regimens require alkalinization of urine with increased flow by hydration. Methotrexate can be sequestered in thirdspace collections and diffuse back into the general circulation, causing prolonged myelosuppression. Less frequent adverse effects include reversible increases in transaminases and hypersensitivity-like pul­ monary syndrome. Chronic low-dose methotrexate can cause hepatic fibrosis. When administered to the intrathecal space, methotrexate can cause chemical arachnoiditis and CNS dysfunction. Pemetrexed is a folate-directed antimetabolite that inhibits the activity of several enzymes, including thymidylate synthetase (TS), dihydrofolate reductase, and glycinamide ribonucleotide formyltrans­ ferase. To avoid toxicity to normal tissues, pemetrexed is given with low-dose folate and vitamin B12 supplementation. Pemetrexed has notable activity against certain lung cancers and, in combination with cisplatin, also against mesotheliomas. 5-Fluorouracil (5-FU) represents an early example of “rational” drug design in that tumor cells incorporate radiolabeled uracil more efficiently into DNA than normal cells. 5-FU is metabolized in cells to 5′FdUMP, which inhibits TS. In addition, misincorporation can lead to single-strand breaks, and RNA can aberrantly incorporate FUMP. 5-FU is metabolized by dihydropyrimidine dehydrogenase, and defi­ ciency of this enzyme can lead to excessive toxicity from 5-FU. Oral bioavailability varies unreliably, but prodrugs such as capecitabine have been developed that allow at least equivalent activity to parenteral 5-FU-based approaches. Intravenous administration of 5-FU leads to bone marrow suppression after short infusions but to stomatitis after prolonged infusions. Leucovorin augments the activity of 5-FU by pro­ moting formation of the ternary covalent complex of 5-FU, the reduced folate, and TS. Less frequent toxicities include CNS dysfunction, with prominent cerebellar signs, and endothelial toxicity manifested by thrombosis, including pulmonary embolus and myocardial infarc­ tion. Trifluridine is a fluorinated pyrimidine that as the triphosphate is directly incorporated into DNA, evoking DNA damage, and as the monophosphate can inhibit TS. It is administered as a fixed-dose combination with tipiracil, an inhibitor of trifluridine degradation by thymidine phosphorylase. Cytosine arabinoside (ara-C) is incorporated into DNA after for­ mation of ara-CTP, resulting in S-phase–related toxicity. Continuous infusion schedules allow maximal efficiency, with uptake maximal at 5–7 μM. Ara-C can be administered intrathecally. Adverse effects include nausea, diarrhea, stomatitis, chemical conjunctivitis, and cerebellar ataxia. Gemcitabine is a cytosine derivative that is similar to ara-C in that it is incorporated into DNA after anabolism to the triphosphate, rendering DNA susceptible to breakage and repair syn­ thesis, which differs from that in ara-C in that gemcitabine-induced lesions are very inefficiently removed. In contrast to ara-C, gem­ citabine appears to have useful activity in a variety of solid tumors, with limited nonmyelosuppressive toxicities. 6-Thioguanine and 6-mercaptopurine (6-MP) are used in the treat­ ment of acute lymphoid leukemia. Although administered orally, they display variable bioavailability. 6-MP is metabolized by xanthine oxi­ dase and therefore requires dose reduction when used with allopurinol. 6-MP is also metabolized by thiopurine methyltransferase; genetic deficiency of thiopurine methyltransferase results in excessive toxicity. Fludarabine phosphate is a prodrug of F-adenine arabinoside (F-ara-A). F-ara-A is incorporated into DNA and can cause delayed cytotoxicity even in cells with low growth fraction, including chronic lymphocytic leukemia and follicular B-cell lymphoma. CNS and peripheral nerve dysfunction and T-cell depletion leading to opportu­ nistic infections can occur in addition to myelosuppression. Agents that indirectly affect purine and pyrimidine metabolism with anti-metabolite-like effects include hydroxyurea, which reversibly inhibits ribonucleotide reductase, resulting in S-phase block. It is orally bioavailable and useful for the acute management of myeloprolifera­ tive states. Asparaginase is a bacterial enzyme that causes breakdown of extracellular asparagine required for protein synthesis in certain leukemic cells. This effectively stops tumor cell DNA synthesis, as DNA synthesis requires concurrent protein synthesis. Because aspara­ ginase is a foreign protein, hypersensitivity reactions are common, as are effects on organs such as pancreas and liver that normally support continuing protein synthesis of secreted products. This may result in decreased insulin secretion with hyperglycemia, with or without hyperamylasemia and clotting function abnormalities. Close moni­ toring of clotting functions should accompany use of asparaginase. Paradoxically, owing to depletion of rapidly turning over anticoagulant factors, thromboses particularly affecting the CNS may also be seen with asparaginase. Mitotic Spindle Inhibitors  Microtubules form the mitotic spin­ dle, and in interphase cells, they are responsible for the cellular “scaf­ folding” along which various motile and secretory processes occur. Microtubules are composed of repeating heterodimers of α and β iso­ forms of the protein tubulin. Vincristine binds to the tubulin heterodi­ mer with the result that microtubules are disaggregated. This results in the block of growing cells in M-phase, where a structurally disordered mitotic spindle apparatus is a powerful proapoptotic signal (Fig. 78-3). Vincristine is metabolized by the liver, and dose adjustment in the pres­ ence of hepatic dysfunction is required. It is a powerful vesicant, and infiltration can be treated by local heat and infiltration of hyaluroni­ dase. At clinically used intravenous doses, neurotoxicity in the form of glove-and-stocking neuropathy is frequent. Acute neuropathic effects include jaw pain, paralytic ileus, urinary retention, and the syndrome of inappropriate antidiuretic hormone secretion. Myelosuppression is not seen at conventional doses. Vinblastine is similar to vincristine, except that it tends to be more myelotoxic, with more frequent throm­ bocytopenia and also mucositis and stomatitis. Vinorelbine is a vinca alkaloid that appears to have differences in resistance patterns in com­ parison to vincristine and vinblastine; it may be administered orally. CHAPTER 78 The taxanes include paclitaxel and docetaxel. These agents differ from the vinca alkaloids in that the taxanes stabilize microtubules against depolymerization. The “stabilized” microtubules function abnormally and are not able to undergo the normal dynamic changes of microtubule structure and function necessary for cell cycle comple­ tion. Taxanes are among the most broadly active antineoplastic agents for use in solid tumors, with evidence of activity in ovarian, breast, prostate, and non-small cell lung cancers, and Kaposi’s sarcoma. They are administered intravenously, and their vehicles cause hypersensi­ tivity reactions. Premedication with dexamethasone (8–16 mg orally or intravenously 12 and 6 h before treatment) and diphenhydramine (50 mg) and cimetidine (300 mg), both 30 min before treatment, decreases but does not eliminate the risk of hypersensitivity reactions to the paclitaxel vehicle. A protein-bound formulation of paclitaxel (called nab-paclitaxel) has at least equivalent antineoplastic activity and decreased risk of hypersensitivity reactions. Paclitaxel may also cause myelosuppression, neurotoxicity in the form of glove-and-stocking numbness, and paresthesia. Docetaxel causes comparable degrees of myelosuppression and neuropathy. Docetaxel uses a different vehicle that can cause fluid retention in addition to hypersensitivity reactions; dexamethasone premedication with or without antihistamines is also generally used. Cabazitaxel is a taxane with somewhat better activity in prostate cancers than earlier generations of taxanes, perhaps due to superior delivery to sites of disease. Principles of Cancer Treatment Epothilones represent a class of microtubule-stabilizing agents optimized for activity in taxane-resistant tumors. Ixabepilone has clear evidence of activity in breast cancers resistant to taxanes and anthra­ cyclines such as doxorubicin. Side effects include myelosuppression and peripheral sensory neuropathy. Eribulin is a microtubule-directed agent with activity in patients who have had progression of disease on taxanes. It alters dynamics of microtubule remodeling in cells. ■ ■ANTIBODY-DRUG CONJUGATES In an effort to improve therapeutic index and enhance antitumor effect, antibody-drug conjugates (ADCs; Fig. 78-4) have recently entered clin­ ical practice. In this approach, humanized monoclonal antibodies are covalently linked to cytotoxic agents by “linkers.” When bound to tar­ get antigens on tumor cells, the nature of the linker determines whether the cytotoxic agent is released only after the ADC is internalized by degradation in a lysosomal compartment, or release of the cytotoxin might occur extracellularly by proteases or physical properties of the tumor microenvironment, in the latter case allowing “bystander” cell killing. Of importance is selection of antibodies with sufficient tumor TABLE 78-6  Antibody-Drug Conjugates TOXIC MECHANISM TARGET ANTIGEN DISEASE ACTIVITY NOTES DNA Structure Gemtuzumab ozogamicin CD33 Acute myeloid leukemia, CD33+ IR*, My, ↑LFTs ± VOD Inotuzumab ozogamicin CD22 Pre-B acute lymphoid leukemia IR*, My, ↑LFTs ± VOD, ↑QT Loncastuximab tesirine-lpyl CD19 Diffuse large B-cell lymphoma VLS, My, Der Microtubule Structure Ado-trastuzumab emtansine HER2 Breast cancer, HER2+ IR, ↑LFTs, ↓LVEF, My, Plm, Neu Belantamab mafadotin-blm CD38 Myeloma IR, My, Cor Brentuximab vedotin CD30 Hodgkin’s disease; anaplastic large-cell lymphoma; mycosis fungoides, CD30+ Enfortumab vedotin Nectin-4 Urothelial cancer ↑Glucose ± DKA, Neu, Cor, Ves, Der Mirvetuximab soravtansine-gynx Folate receptor α (FRα+) Ovary, peritoneal, fallopian tube cancer, FRα+ Cor, Neu, My Polatuzumab vedotin CD79b High-grade B-cell lymphoma Neu, IR*, My, PML, TLS, ↑LFTs Tisotumab vedotin-tftv Tissue factor Uterine cervix cancer Neu, ↑PT, ↑PTT, Cor, bleeding, Plm Topoisomerase I Fam-trastuzumab deruxtecan-nxki HER2 HER2 1+/weak BC, HER2 activating mutation+ NSCLC, HER2+ gastric Sacituzumab govitecan-bziy Trop2 Triple-negative BC, HR+/HER2– BC, urothelial cancer PART 4 Oncology and Hematology Note: Data abstracted in part from publicly available U.S. Food and Drug Administration label. All agents in this class have the potential for prominent embryofetal toxicity; use without contraception by female patients of childbearing potential is not recommended. Effective contraception for female partners who are of childbearing potential of patients undergoing treatment should also be considered; use during lactation is also not recommended; all DNA interacting agents have theoretical risk of late secondary neoplasms, particularly where noted. Indications and events of prominent general medical importance include the following: BC, breast cancer; Cor, corneal keratopathy, consider pretreatment ophthalmologic exam with prophylactic lubricating eyedrops ± ocular steroids; CYP___, interaction with drugs metabolized by the indicated cytochrome(s) P450; DA-H, dose adjust for hepatic dysfunction; DA-R, dose adjust for renal dysfunction; Der, dermatologic toxicity; DKA, diabetic ketoacidosis; G-CSF, granulocyte colony-stimulating factor; HER2, human epidermal growth factor receptor 2; HR, hormone receptor; ILD, interstitial lung disease; IR, infusion reaction; IR*, infusion reaction prophylaxis specifically recommended; LFT, liver function tests; ↓LVEF, left ventricular ejection fraction, monitor echocardiogram; My, anemia, decrease in white blood cells, platelets, with risk of neutropenic fever, hemorrhage, therefore dose reduce or hold dose for decreased neutrophil or platelet counts unless marrow infiltrated by drug-responsive tumor; N, nausea; Neu, peripheral neuropathy; Plm, pulmonary; PML, progressive multifocal leukoencephalopathy risk; PT, prothrombin time; PTT, partial thromboplastin time; ↑QT, pre- and intratreatment electrocardiogram monitoring, normalize K+, Mg2+, ionized Ca2+; R, renal injury possible; TLS, risk of tumor lysis syndrome if brisk response; UGT___, metabolism by UDP-glucuronosyltransferase of the indicated genotype; V, vomiting; Ves, extravasation injury possible; VLS, vascular leak syndrome; VOD, veno-occlusive liver disease. cell selectivity to avoid damage to normal tissue. In addition, the linker strategy should have low spontaneous release of the cytotoxic agent prior to reaching the tumor environment. Table 78-6 lists currently approved ADCs and features of importance relevant to their use for the general internist. Three major groups of ADCs are currently available, based on the nature of the cytotoxic payload. ADCs targeting DNA structure include those based on calicheamicin, a DNA-interacting antitumor antibiotic too toxic for clinical use but, when used as an ADC, can be useful in the treatment of CD33+ acute myeloid leukemia (gemtuzumab ozogamicin) and CD22+ acute lymphocytic leukemia (inotuzumab ozogamicin). Patients must be monitored for hypersensitivity reactions and for hepatotoxicity due to veno-occlusive disease of hepatic veins, resulting from release of the calicheamicin or its metabolites in the liver. Likewise, the minor groove binder and DNA alkylator pyrrolo­ benzodiazepine dimer is the basis for CD19-directed loncastuximab tesirine-lpyl, whose use in refractory diffuse large B-cell lymphoma can be complicated by vascular leak syndrome, cytopenias, and cutaneous reactions. ADCs targeting microtubules (in all cases with the potential for cytopenias and neuropathic adverse events) are of two types. Maytan­ sine derivatives include ado-trastuzumab emtansine, which is an ADC employing the HER2/neu-directed trastuzumab and a highly toxic microtubule-targeted emtansine, which by itself is too toxic for human use; the ADC shows valuable activity in patients with breast cancer who have developed resistance to trastuzumab alone (still watch for cardiac and pulmonary side effects). Mirvetuximab soravtansine-gynx targets folate receptor α in refractory ovarian cancers (monitor for corneal side effects). The second microtubule-directed class of ADCs is derived from the microtubule poison monomethylauristatin E as cytotoxic agent. Brentuximab vedotin is an anti-CD30 ADC with activ­ ity in neoplasms such as Hodgkin’s lymphoma where the tumor cells frequently express CD30. Polatuzumab vedotin analogously targets Neu, IR, My, Plm, R, TLS, CYP3A4, ↑LFTs, DA-H, DA-R N/V prophylaxis, ILD prompt evaluate cough, dyspnea, My, ↓LVEF IR*, N/V prophylaxis, diarrhea consider loperamide, My esp UGT1A1*28, consider G-CSF CD79a in B-cell lymphomas. Enfortumab vedotin uses an antibody to NECTIN4 to target the vedotin “warhead” to urothelial neoplasms expressing that target. Belantamab mafodotin targets BCMA (B-cell maturation) expressed myeloma but using a distinct microtubule toxin derived from auristatin F. Belantamab mafodotin can cause ocular keratopathy, which requires prospective monitoring. Topoisomerase I–directed ADCs, including fam-trastuzumab derux­ tecan-nxki and sacituzumab govitecan-bziy, are ADCs that allow specific targeting of camptothecin and SN-38, respectively to HER2positive neoplasms (monitoring for interstitial pneumonitis and cardiac dysfunction) and, in the latter case, triple-negative breast cancers, which abundantly express the antibody target Trop2, a cell surface glycoprotein first discovered in trophoblast cells (but diarrhea should be vigorously addressed with loperamide, similar to what might be encountered with irinotecan). Both agents can cause cytopenias, nausea, and vomiting. ■ ■CANCER MOLECULAR TARGETED THERAPY Agents in this class share the characteristic that they are directed at specific cancer cell molecular targets important in the proliferation of tumors. While these agents can ultimately lead to tumor cell death, this occurs by altered regulation of a specific biochemical pathway affecting tumor cell susceptibility to apoptosis or growth arrest (Fig. 78-3). Since many approved agents of this type are directed at specific mutations present at diagnosis or that arise during the course of a patient’s clinical course, their use must be guided by refined diagnostic strategies. Initial molecular testing of a diagnostic biopsy, with repeated biopsies as war­ ranted, should be considered. Alternatively liquid biopsies to examine plasma DNA shed from tumors or present in circulating tumor cells have entered into routine clinical use to assist in making decisions about best strategies to consider. Hormone Receptor–Directed Therapy  Steroid hormone receptor–related molecules were arguably the first “molecular target” classes of anticancer drugs. When bound to their ligands, these recep­ tors can alter gene transcription in hormone-responsive tissues. While in some cases, such as breast cancer, demonstration of the target hor­ mone receptor is necessary for their use, in other cases such prostate cancer (androgen receptor) and lymphoid neoplasms (glucocorticoid receptor), the relevant receptor is always present in the tumor. Glucocorticoids are generally given in “pulsed” high doses in leu­ kemias and lymphomas, where they induce cell death in tumor cells. Cushing’s syndrome and inadvertent adrenal suppression on with­ drawal from high-dose glucocorticoids can be significant complica­ tions, along with infections common in immunosuppressed patients, in particular Pneumocystis pneumonia, which classically appears a few days after completing a course of high-dose glucocorticoids. Tamoxifen is a partial estrogen receptor (ER) antagonist; it antago­ nizes growth in wild-type (ER; also designated ESR1 to specify estro­ gen receptor α) breast tumors, mirroring its effect on breast tissue, but owing to agonistic activities in vascular and uterine tissue, side effects include increased risk of thromboembolic phenomena and a small increased incidence of endometrial carcinoma, which appears after chronic use (usually >5 years). Progestational agents—including medroxyprogesterone acetate, androgens including fluoxymesterone (Halotestin), and paradoxically, estrogens—have approximately the same degree of activity in primary hormonal treatment of breast can­ cers that have elevated expression of ER protein. Estrogen itself is not used often due to prominent cardiovascular and uterotropic activity. Aromatase refers to a family of enzymes that catalyze the forma­ tion of estrogen in various tissues, including ovary, peripheral adipose tissue, and some tumor cells. Aromatase inhibitors are of two types: irreversible steroid analogues such as exemestane and the reversible inhibitors such as anastrozole and letrozole. Anastrozole is superior to tamoxifen in the adjuvant treatment of breast cancer in postmeno­ pausal patients with ER-positive tumors. Letrozole treatment affords benefit following tamoxifen treatment. Adverse effects of aromatase inhibitors may include an increased risk of osteoporosis, fatigue, and altered serum lipids. ESR1 mutations of various types are detected at increased frequency after resistance to aromatase inhibitors occurs. Fulvestrant is the prototype of a selective ER degrader. As a result of its binding, the ER is degraded and ER-dependent proliferation may diminish. Metastatic prostate cancer is treated primarily by androgen depriva­ tion. Orchiectomy causes responses in 80% of patients. If not accepted by the patient, testicular androgen suppression can also be induced by luteinizing hormone–releasing hormone (LHRH) agonists such as leuprolide and goserelin. These agents cause tonic stimulation of the LHRH receptor, with loss of normal pulsatile activation resulting in net decreased output of luteinizing hormone (LH) by the anterior pituitary. Therefore, as primary hormonal manipulation in prostate cancer, one can choose orchiectomy or an LHRH agonist, but not both. This path­ way can also be blocked by relugolix, an oral gonadotropin-releasing hormone antagonist. The addition of androgen receptor blockers, including flutamide or bicalutamide, is of uncertain additional benefit in extending overall response duration, although pretreatment with these agents before LHRH agonists is important to avoid a surge in testosterone after initial LH release. Enzalutamide also binds to the androgen receptor and antagonizes androgen action in a mechanistically distinct way. Somewhat analogous to inhibitors of aromatase, agents have been derived that inhibit testosterone and other androgen synthesis in the testis, adrenal gland, and prostate tissue. Abiraterone inhibits 17 α-hydroxylase/C17,20 lyase (CYP17A1) and has been shown to be active in prostate cancer patients experiencing disease progression despite androgen blockade. Tumors that respond to a primary hormonal manipulation may fre­ quently respond to second and third hormonal manipulations. Thus, breast tumors that had previously responded to tamoxifen have, on relapse, notable response rates to withdrawal of tamoxifen itself or to subsequent addition of an aromatase inhibitor or progestin. Likewise, initial treatment of prostate cancers with leuprolide plus flutamide may be followed after disease progression by response to withdrawal of flutamide. These responses may result from the removal of antagonists from mutant steroid hormone receptors that have come to depend on the presence of the antagonist as a growth-promoting influence. Non-Receptor-Linked Tyrosine Kinase Antagonists  Table 78-7 lists currently approved non–hormone receptor pathway-directed molecularly targeted chemotherapy agents, with features of their use of import to the generalist, particularly in recognizing potential druginduced morbidities and interactions with other classes of drugs. The basis for discovery of drugs of this type was the prior knowledge of oncogene-directed pathways driving tumor growth (Fig. 78-3). In most cases, non-receptor tyrosine kinases ultimately activate signal­ ing through the RAF/MEK/MAP kinase cascade, in common with the receptor-linked tyrosine kinases. Diagnostic demonstration of an active non-receptor tyrosine kinase may guide selection of an agent. A repeated preclinical and clinical observation in a variety of tumor types is that mutational activation of the tyrosine kinase target induces a state of “oncogene addiction” on the part of the tumor. This then is the basis for a “synthetic lethal” effect of the kinase inhibitor with respect to tumor viability. In hematologic tumors, the prototypic agent of this type is imatinib, which targets the ATP binding site of the p210bcr-abl protein tyrosine kinase that is formed as the result of the chromosome 9;22 translo­ cation producing the Philadelphia chromosome in chronic myeloid leukemia (CML). Subsequent studies have shown value of imatinib in gastrointestinal stromal tumor (GIST) and certain myeloprolifera­ tive disorders, driven by certain mutants of cKIT and platelet-derived growth factor receptor (PDGFR). Imatinib has lesser activity in the blast phase of CML, where the cells may have acquired additional muta­ tions in p210bcr-abl itself or other genetic lesions. Imatinib’s side effects are relatively limited in most patients and include hepatic dysfunction, diarrhea, and fluid retention. Rarely, patients receiving imatinib have decreased cardiac function, which may persist after discontinuation of the drug. The quality of response to imatinib enters into the decision about when to refer patients with CML for consideration of stem cell transplant approaches. Nilotinib is a tyrosine protein kinase inhibitor with activity against p210bcr-abl but with increased potency and perhaps better tolerance by certain patients. Dasatinib, another inhibitor of the p210bcr-abl oncoproteins, also has activity against certain mutant variants of p210bcr-abl that are refractory to imatinib and arise during therapy or are present de novo. Dasatinib also has inhibitory action against kinases belonging to the src tyrosine protein kinase family; this activity may contribute to its effects. The T315I mutant of p210bcr-abl is resistant to imatinib, nilotinib, bosutinib, and dasatinib; ponatinib has activity in patients with this T315Ip210bcr-abl, but ponatinib has noteworthy associated thromboembolic toxicity. Use of this class of targeted agents is thus critically guided not only by the presence of the p210bcr-abl tyro­ sine kinase, but also by the presence of specific mutations in the ATP binding site. Asciminib is a first-in-class non-ATP site p210bcr-abl inhibi­ tor that also has activity in BRC/ABL T315I mutant CML. CHAPTER 78 Principles of Cancer Treatment Janus kinases (JAK) 1 and 2 are mutated in certain myeloprolifera­ tive states; cytopenias and infrequent arrhythmias infrequently com­ plicate the use of ruxolitinib, the prototypic JAK inhibitor. Bruton’s tyrosine kinase (BTK) is an intrinsic component of B-cell antigen receptor signaling activated in many types of proliferating B cells and B-cell neoplasms. Irreversible inhibitors of BTK, including ibrutinib, acalabrutinib, and zanubrutinib, have noteworthy activity in certain lymphomas. Cytopenias and cardiac arrhythmias can occur, along with propensity to infection (indeed, the BTK was discovered as deficient in congenital hypogammaglobulinemia, presenting with repeated infec­ tions in childhood). Initial use of the BTK inhibitors requires consid­ eration of prophylaxis against tumor lysis syndrome in case of a robust lympholytic effect of the agent. If and when resistance to irreversible BTK inhibitors develops (often associated with a C481S mutation), the noncovalent inhibitor pirtobrutinib may have activity. Receptor-Linked Tyrosine Kinase Antagonists  Mutated EGFR drives a significant fraction of non-small-cell lung cancers (NSCLCs). Erlotinib and gefitinib are the prototypic EGFR antagonists that, in early clinical trials, showed evidence of responses in a small TABLE 78-7  Molecularly Targeted Agents DRUG TARGET/INDICATION ADVERSE EVENTS NOTES Non-Receptor Tyrosine Kinase Antagonists Acalabrutinib BTK/certain B-cell malignancies My, atrial fibrillation/flutter, infection CYP3A4; avoid PPIs and stagger doses with H2 blockers; irreversible BTK inhibitor Asciminib BCR/ABL/CML chronic phase after 2 TKIs or with BCR/ABL T315I My, ↑lipase, ↑amylase, HBP, hypersensitivity, cardiac events Bosutinib BCR/ABL wild-type, some mutants/CML My, ↑LFT, cardiac, R, fluid retention CYP3A4, PPI (use short-acting antacids or H2 blocker staggered with dose) Dasatinib BCR/ABL/Ph+ CML, Ph+ ALL My, pulmonary hypertension, fluid retention, ↓LVEF, ↑LFT, Der Ibrutinib As with acalabrutinib My, stomatitis, HBP, arrhythmia, TLS CY3A4, second primary malignancy Imatinib ABL, BCR/ABL wild-type, cKIT PDGFR/ CML, some ALL, certain GISTs, eosinophil, mast cell, myelodysplastic syndromes My, edema, fluid retention, ↓LVEF, ↑LFT rare liver failure, GI perforation, Der, TLS, ↓CrCl Nilotinib BCR/ABL wild-type/CML CHF, ↑LFT, ↑QT, fluid retention, ↑lipase, TLS CYP3A4, CYP2C8, CYP2C9, CYP2D6, CYP2B6; no food 2 h before, 1 h after dose; monitor electrolytes, TFTs Pirtobrutinib As with acalabrutinib My, arrhythmia, infection, hemorrhage DA-R, CYP3A4; CYP2C8, 2C19, Pgp, BCRP substrates; reversible BTK inhibitor, second primary malignancy Ponatinib T315I mutant BCR/ABL CML Clotting, ↑LFT, TLS, ↓LVEF, pancreatitis, Neu, arrhythmia PART 4 Oncology and Hematology Ruxolitinib JAK1,2/myeloproliferative disorders My, dizziness, headache DA-R, DA-H, CYP3A4 or with fluconazole >200 mg doses except with GVHD Zanubrutinib As with acalabrutinib My, hemorrhage, cardiac arrhythmias CYP3A4 Receptor-Linked Tyrosine Kinase Antagonists Afatinib Nonresistant ATP site mutated EGFR/ NSCLC D, Der, Cor, ILD; ↑LFT DA-R, DA-Pgp inhibitors, no food 2 h before, 1 h after dose Alectinib ALK rearranged/NSCLC ↑LFT, ILD, R, bradycardia, ↑CPK Administer with food; can have muscle pain, tenderness, weakness Avapritinib PDGFR mutants/GIST, mastocytosis N, edema, CNS, sleep, mood change, hallucinations Capmatinib MET + exon 14 skip/NSCLC ILD, ↑LFT, photosensitivity, pancreatitis, hypersensitivity Ceritinib ALK rearranged/NSCLC GI, ↑LFT, ↑glucose, ↑QT, bradycardia, pancreatitis Crizotinib ALK rearranged/NSCLC; inflammatory myofibroblastic tumor, anaplastic largecell lymphoma ILD, ↑LFT, ↑QT, bradycardia, ↓vision CY3A4 Dacomitinib EGFR exon 19 deletion or exon 21 L858R/ NSCLC D, Der: hold and/or dose reduce; ILD (permanently discontinue) Erdafitinib FGFR2/3 altered/urothelial cancer after Pt regimen Der, D, stomatitis, retina (ophthalmologic exam before/during) Erlotinib As with afatinib; also wild-type EGFR/ NSCLC 2nd line or pancreatic 1st line with gemcitabine Der, D, R, ILD, ↑LFT, rare microangiopathic anemia Fruquintinib Target VEGFR1,2,3/CRC HBP, hemorrhage, arterial thromboses, infection, GI perforation, ↑LFT, proteinuria, ↓wound healing, allergic bronchospasm Futibatinib FGFR2 gene fusions/ cholangiocarcinoma Retina (ophthalmologic exam before/during) CYP3A4, Pgp substrates; ↑PO4 due to effect on FGFR2/3/ Klotho, tissue and vascular calcification Gefitinib As with afatinib Der, D, ILD, ocular keratitis, GI perforation CYP3A4; avoid with PPIs; monitor warfarin effect Gilteritinib FLT3 mutated/AML ↑LFT, ↑QT, myalgia/arthralgia, N, V, GI, Der, edema, dyspnea Infigratinib FGFR2 variants/cholangiocarcinoma Retina (ophthalmologic exam before/during) CYP3A4, avoid gastric acid reduction or stagger with H2 blockers or locally acting agents, ↑PO4 due to effect on FGFR2/3/Klotho, soft tissue including myocardial mineralization Lapatinib HER2/HER2+ breast cancer ↓LVEF, ↑LFT, N, V, D, PPED CYP3A4, CYP2C8, Pgp substrate; interaction, ILD, ↑QT Larotrectinib NTRK gene fusion without a resistance mutation/any solid tumor CNS with potential cognitive impairment; ↑LFT CYP3A4 Lorlatinib ALK rearranged/NSCLC Hyperlipidemia, AV block, CNS including seizures, mental status changes Neratinib As with lapatinib N, V, D, abdominal pain, ↑LFT CYP3A4, aggressive D prophylaxis with loperamide; avoid PPIs and stagger H2 blocker doses CYP3A4, CYP2C9, Pgp; not an ATP site inhibitor but inhibit by allosteric mechanism binding to myristoyl pocket in BCR/ABL CYP3A4, avoid PPIs and stagger doses with H2 blockers; caution with agents with ↑QT DA-H, DA-R, CYP3A4, CYP2D6; hemorrhage at tumor site in GIST, cardiogenic shock with high eosinophil levels; monitor TFTs with thyroid replacement CYP3A4, PRES possible CYP3A4, monitor for intracranial hemorrhage   CYP3A4, CYP2C9; if ILD, permanently discontinue CYP2D6; avoid PPIs, use local antacids or give 6 h before or 10 h after H2 blockers CYP2C9, CYP3A4, also organic cation transporter 2 and Pgp substrates, give 6 h before/after Pgp substrates; ↑PO4 due to effect on FGFR2/3/Klotho CYP3A4, give 1 h before/2 h after meals, avoid PPIs, stagger with H2 blockers; alter warfarin effect CYP3A4; unusual, PPED, PRES Monitor for PRES, pancreatitis, ↑Cr, eye disorders CYP3A4 with severe ↑LFT with CYP3A interactors; monitor for ILD and discontinue if occur (Continued) TABLE 78-7  Molecularly Targeted Agents (Continued) DRUG TARGET/INDICATION ADVERSE EVENTS NOTES Osimertinib EGFR exon 19 altered or exon 21L858R or T790M mutations/NSCLC ILD, ↑QT, ↓LVEF, Cor CYP3A4 Pemigatinib FGFR2 fusion or other rearrangement/ cholangiocarcinoma FGFR1 rearranged myeloid/lymphoid neoplasms N, D, stomatitis, ↑PO4 due to effect on FGFR2/3/Klotho Pralsetinib RET mutant or fusion/NSCLC, thyroid carcinomas ILD, HBP, hemorrhage, ↑LFT, TLS, ↓wound healing Quizartinib FLT3 mutated/AML ↑QT with risk of cardiac arrest CYP3A4 Repotrectinib Target ROS1 rearranged/NSCLC CNS, ILD, ↑LFT, myalgia, ↑CPK CYP3A4, Pgp, OCs; also target TRKA,B,C Selpercatinib RET mutant or fusion/NSCLC, thyroid carcinomas ↑LFT, ↑QT, HBP, bleeding, ↓wound healing; hold 1 week prior and 2 weeks after surgery Tepotinib MET with exon 14 skipping mutations/ NSCLC ILD, ↑LFT CYP3A4, Pgp; DA-H Tucatinib As with lapatinib ↑LFT, D CYP3A4, CYP2C8 KRAS-G12C/RAF/MEK Antagonists Adagrasib KRAS G12C mutation/NSCLC N, V, D, ↑LFT, ↑QT, ILD CYP3A4, CYP2C9, CYP2D6, agents that ↑QT Binimetinib Targets MEK/BRAF V600E or V600K mutated melanoma combined with encorafenib ↓LVEF, venous thrombosis; ocular, ILD, ↑LFT, rhabdomyolysis Cobimetinib Targets MEK/BRAF V600E or V600K melanoma combined with vemurafenib; alone in BRAF V600E or V600K histiocytic neoplasms Hemorrhage, retinal ↓LVEF, Der, photosensitivity, rhabdomyolysis, ↑LFT Dabrafenib Targets BRAF in BRAF V600E or V600K mutated tumors (not CRC) with trametinib Hemorrhage, uveitis ↓LVEF, Der, ↑glucose, hemolysis if G6PD deficient, pyrexia Encorafenib Targets BRAF in BRAF V600E or V600K mutated tumors combined with binimetinib (melanoma) or CRC with cetuximab Hemorrhage, uveitis, ↑QT CYP3A4, organic anion transporter 1B1, BCRP interactions, new malignancies, cutaneous and noncutaneous Sotorasib KRAS G12C mutation/NSCLC ↑LFT, ILD, N, V, D Avoid with PPIs and H2 receptor antagonists; if necessary, administer 4 h before or 10 h after a local antacid, avoid CYP3A4, Pgp substrates Trametinib Targets MEK/BRAF V600E or V600K mutated tumors (not colorectal) combined with dabrafenib Hemorrhage, venous thromboembolism, ↓LVEF, ILD, pyrexia, Der, ↑glucose Vemurafenib Targets BRAF in BRAF V600E or V600K mutated melanoma and ErdheimChester disease Der including Stevens-Johnson, anaphylaxis and allergic hypersensitivity, ↑QT, ↑LFT, photosensitivity, radiation recall Multikinase Antagonists Axitinib VEGFR, PDGFR, KIT/RCC HBP, hemorrhage, thrombotic events; D, other GI including GI perforation, PPED, hypothyroidism, PRES, proteinuria, ↑LFT Brigatinib ALK, EGFR/NSCLC ILD, bradycardia, HBP, visual disturbances, ↑glucose, ↑CPK Cabozantinib VEGFR2, MET, AXL, RET/RCC, HCC, certain thyroid carcinoma HBP, hemorrhage, thrombotic events, D, other GI including fistula, perforation, wound healing, PRES, PPED, proteinuria, ONJ Capivasertib Target PIK3CA/AKT1/PTEN- axis; BC-HR(+) with mutation in pathway Hypersensitivity reactions, Der, ↑glucose, pneumonitis, ILD, D Entrectinib NRTK gene fusion/any solid tumor; ROS1 gene alteration/NSCLC ILD, ↑LFT, photosensitivity, ↓LVEF, CNS effect, skeletal fractures; hyperuricemia, ↑QT, Fedratinib JAK2, FLT3, RET/myeloproliferative diseases My, N, V, D, ↑LFT pancreatitis, encephalopathy: check thiamine levels prior, replete if deficient Lenvatinib VEGFR1/2/3, FGFR1/2/3/4, PDGFRα, KIT, RET/thyroid, RC, HCC, endometrial cancer HBP, ↓LVEF, bleeding, arterial/venous clots, RF, ONJ, proteinuria, ↑LFT, GI including D, fistula/perforation, ↓wound healing, ↑QT, ↓Ca2+, PRES, ↓TFT Midostaurin FLT3 mutated/AML newly diagnosed, mast cell neoplasms ILD; N, D CYP3A4; many other protein kinase targets in addition to FLT3 CYP3A4, retinal detachment: ophthalmologic exam with ocular tomography before and every 2–3 months during treatment CYP3A4, Pgp Avoid with antacids, but take if not avoidable with food if PPI or stagger with other antacid, CYP3A, CYP2C8 DA-H CHAPTER 78 CYP3A4, new malignancies, cutaneous and noncutaneous Principles of Cancer Treatment CYP3A4, CYP2C8, CYP2C9, CYP2C19, CYP2B6, new malignancies, cutaneous and noncutaneous Colitis with GI perforation, ocular including retinal vein occlusion, new malignancies, cutaneous and noncutaneous Dupuytren’s contracture and plantar fascial fibromatosis has occurred; usually combined with cobimetinib in melanoma; CYP3A4, CYP1A2, CYP2D6, new primary cutaneous and noncutaneous neoplasms DA-H, CYP3A4/5 CYP3A4, decreased hormonal contraceptive effectiveness CYP3A4 CYP3A4, CYP2C9, BCRP substrates CYP3A4, ophthalmologic exam if vision change CYP3A4, CYP2C19 DA-H, DA-R (Continued) TABLE 78-7  Molecularly Targeted Agents (Continued) DRUG TARGET/INDICATION ADVERSE EVENTS NOTES Pazopanib VEGFR 1/2/3, KIT, PDGFR, and FGFR/ RCC soft tissue sarcoma (not GIST or adipocytic) D, HBP; arterial and venous thrombosis ± embolism, ↑QT, hemorrhage, ↑LFT potentially severe/fatal; GI perforation or fistula; proteinuria, ↓TFT, ↓LVEF, PRES, ILD, thrombotic microangiopathy Regorafenib VEGFR1/2/3, KIT, RET, PDGFR-α/β, FGFR1/2, TIE2, DDR2, Trk2A, Eph2A, RAF1, BRAF, BRAF V600E, SAPK2, PTK5, and ABL/CRC, GIST ↑LFT potentially severe/fatal; hemorrhage, thromboses, PPED, Der, HBP, ↓LVEF, ↑QT, GI perforation Sorafenib VEGFR2, VEGFR3, PDGFRβ, Flt3, KIT, RAF1, BRAF/RCC, HCC, differentiated thyroid carcinoma D, ↑LFT potentially severe/fatal; hemorrhage, PPED, Der, HBP, ↓LVEF, ↑QT, GI perforation Sunitinib VEGFRs; PDGFR, RET, KIT; other protein kinases/RCC, pancreatic neuroendocrine, GIST HBP, ↑LFT potentially severe/fatal; hemorrhage, GI perforation, CHF, altered TFTs, ONJ, ↓wound healing, proteinuria, R Vandetanib VEGFR, RET, EGFR/medullary thyroid cancer D, Der, HBP, ↑QT, thromboses, ↓LVEF, fistulas, ILD, ONJ, proteinuria, PRES Cyclin-Dependent Kinase (CDK) Inhibitors Abemaciclib CDK4/6/HR+ BC D, My, ↑LFT, venous thromboembolism, ILD CYP3A4, avoid concomitant use of ketoconazole Palbociclib CDK4/6/HR+ BC D, My, stomatitis, ILD, D CYP3A4 Ribociclib CDK4/6/HR+ BC Der, ILD, ↑QT, ↑LFT, My CYP3A4, agents known to ↑QT PART 4 Oncology and Hematology Protein Homeostasis Modulators Bortezomib Proteasome inhibitor/multiple myeloma, mantle cell lymphoma Neu, N, V, D, C, ↓BP, My, ILD, ↑LFT worsening cardiac disease Carfilzomib Proteasome inhibitor/multiple myeloma ↓LVEF, myocardial ischemia, R, TLS, pulmonary including ARDS, ILD, HBP, IR*, thrombosis, hemorrhage, PRES, thrombocytopenia, thrombotic microangiopathy, ↑LFT potentially severe Ixazomib Proteasome inhibitor/multiple myeloma relapsed, not as maintenance Thrombocytopenia, N, V, D, C, Neu, edema, Der, thrombotic microangiopathy, ↑LFT Nuclear Export Inhibitor Selinexor Targets exportin 1/multiple myeloma, certain DLBCLs My, N, V, D, anorexia, ↓Na+, CNS, cataract development or progression Chromatin-Modifying Epigenetic Modulators DNA Hypomethylating Agents Azacytidine Target DNA methyltransferase/ myelodysplastic syndromes, AML My, ↑LFT, TL, CNS Monitor if renal impairment, more N, V, D if SC administration Decitabine As with azacytidine My Combined with cedazuridine (a cytidine deaminase inhibitor) in an oral regimen Histone Deacetylase Inhibitors Belinostat Peripheral T-cell lymphoma, relapsed or refractory My, ↑LFT, TLS, N, V   Panobinostat Multiple myeloma, relapsed or refractory My, hemorrhage, ↑LFT, ↓Na+, ↓K+, ↓PO4, ↑Cr CYP3A4, CYP2D6, avoid agents that ↑QT Romidepsin CTCL after one systemic therapy My, ↑QT CYP3A4, alter warfarin effect, may ↓ effectiveness of oral contraceptives Vorinostat CTCL after two systemic therapies My, N, V, D, venous thrombosis, ↑glucose Monitor with mild or moderate liver disease Histone Methyltransferase Inhibitors Tazemetostat Target EZH2 mutant or nonmutant/ epithelioid sarcoma, certain follicular lymphomas N, V, C, abdominal pain CYP3A4, increased risk of secondary malignancies (MDS, AML, lymphomas) Transcription Factor Modulation Arsenic trioxide Target PML-RARα and redox homeostasis/t(15;17) acute promyelocytic leukemia ↑QT, hypersensitivity APL differentiation syndrome: with pulmonary dysfunction/infiltrate, pleural/pericardial effusion, fever, treat with dexamethasone ± hydroxyurea Belzutifan Target HIF2α/von Hippel-Lindau (VHL) disease–associated RCC, CNS hemangioblastomas, GI neuroendocrine tumors, non-VHL RCC after PD-1, VEGFR inhibitor Anemia, hypoxia, N, ↑Cr, ↑glucose CYP2C19, UGTB17 Glasdegib Targets smoothened receptor in hedgehog pathway/AML ↑QT CYP3A4, transmission to potentially pregnant partner through semen or to blood product recipient CYP3A4, CYP22D6, CYP2C8 interaction; use with simvastatin increases the risk of ALT elevations and should be undertaken with caution; avoid with PPIs or H2 blocker, stagger with other antacid doses CYP3A4, impaired TSH suppression in thyroid cancer As with regorafenib CYP3A4, rare ↑QT, rare TLS in RCC and GIST with high tumor burden CYP3A4 Rare TLS, PRES Administer after a hemodialysis procedure DA-R, DA-H, CYP3A4 Advise against driving or dangerous equipment operation if CNS altered (Continued) TABLE 78-7  Molecularly Targeted Agents (Continued) DRUG TARGET/INDICATION ADVERSE EVENTS NOTES Nirogacestat Targets γ-secretase to inhibit Notch signaling/desmoid tumor D (can be severe), ovarian dysfunction, ↑LFTs, PO4 and K+ abnormalities Sonidegib Targets smoothened receptor in hedgehog pathway/basal cell carcinoma locally advanced or metastatic Musculoskeletal adverse events with ↑CPK, potential R, N, V, D Tretinoin Target PML-RARα/t(15;17) acute promyelocytic leukemia Der including cheilitis, skin dryness; ↑ intracranial pressure; ↑lipids, ↑LFT, usually resolve Vismodegib As with sonidegib Musculoskeletal adverse events, N, V, D, C Transmission to potentially pregnant partner through semen or to blood product recipient Apoptosis Modulation Venetoclax Targets BCL2/CLL, SLL; AML + azacytidine, decitabine, or low-dose cytarabine My, D, TLS CYP3A4, stagger with Pgp substrates, no live attenuated vaccines prior to, during, or after venetoclax treatment Metabolism Modulation: mTOR Inhibitors/PI Kinase/IDH Inhibitors Alpelisib PIK3CA mutated/HR+HER2– BC Der, hypersensitivity, ↑glucose, ILD, D CYP3A, CYP2C9, BCRP substrates Copanlisib PI3Kα,δ/FL My, HBP, noninfectious pneumonitis, ↑glucose, Der Duvelisib PI3Kδ,γ/CLL, SLL, FL My, infection, D, colitis, Der, pneumonitis, ↑LFTs Enasidenib IDH2 mutated/AML N, V, D, ↑LFTs AML differentiation syndrome with pulmonary dysfunction/infiltrate, pleural/pericardial effusion, fever treat with dexamethasone ± hydroxyurea Everolimus mTOR/RCC, tuberous sclerosis– associated neoplasms, HR+ BC, neuroendocrine, pancreatic, lung, GI NOT functional carcinoid My, noninfectious pneumonitis, infections, hypersensitivity reactions, R, impaired wound healing, ↑glucose, ↑lipids, stomatitis Ivosidenib IDH1 mutated/AML, cholangiocarcinoma, MDS ↑QT, Guillain-Barré syndrome CYP3A4, QT-prolonging agents; AML differentiation syndrome requiring corticosteroid treatment Idelalisib PI3Kδ/non-first-line CLL, SLL, FL Fatal or serious ↑LFTs, D, colitis with GI perforation, pneumonitis, infection, Der, hypersensitivity Olutasidenib IDH1/AML ↑LFTs CYP3A4, differentiation syndrome requiring corticosteroid ± hydroxyurea treatment Sirolimus protein bound particles mTOR/perivascular epithelioid cell tumor (PEComa) My, stomatitis, infection, ↓K+, IR, ↑glucose, ILD, hemorrhage, male infertility Temsirolimus mTOR/RCC Hypersensitivity, ↑LFTs, infection, ILD, stomatitis, thrombocytopenia, N, ↑glucose, ↑lipids, ↓wound healing, GI perforation, R ± proteinuria Poly-ADP Ribose Polymerase (PARP) Inhibitors Niraparib Ovarian, fallopian tube, or primary peritoneal cancer with good response to Pt My, N, V, D, HBP, PRES MDS Olaparib Ovarian: as with niraparib also with various BRCA or HRR mutations; BC mutant BRCA, HER2–; pancreatic mutant BRCA with good response to Pt; prostate with BRCA or HRR mutations My, N, stomatitis, DVT ± PE, rare ILD MDS, CY3A4 Rucaparib As with niraparib; prostate BRCA mutated after hormone and after taxane My, stomatitis, N, V, D, ↑LFTs MDS Talazoparib BC BRCA mutated HER2–; prostate cancer, castrate-resistant HRR mutation(+), with enzalutamide My, N, V, D, ↑LFTs MDS Miscellaneous 177Lu-dotatate Target somatostatin receptor (SSR)/ gastroenterohepatic neuroendocrine tumors (SSR)+ My, R, ↑LFTs, IR, Neuroendocrine hormonal crisis including flushing, diarrhea, hypotension, bronchoconstriction; secondary MDS, risks from radiation exposure 177Lu-vipivotide tetraxetan Target prostate-specific membrane antigen (PSMA)/refractory prostate cancer My, R Temporary or permanent infertility, risks from radiation exposure CYP3A4; avoid PPIs and stagger doses with H2 blockers; nonmelanoma skin cancers; Der: monitor before and during treatment As with glasdegib As with arsenic trioxide; also headache, visual changes may indicate ↑intracranial pressure; check for papilledema CYP3A4 CHAPTER 78 CYP3A4 Principles of Cancer Treatment CYP3A4, Pgp substrates, angioedema with concomitant ACE inhibitors, consider alcohol-free mouthwash when starting treatment; risk of reduced efficacy of vaccination CYP3A4, not with bendamustine or rituximab CYP3A4, avoid live vaccines DA-H, CYP3A4 (Continued) TABLE 78-7  Molecularly Targeted Agents (Continued) DRUG TARGET/INDICATION ADVERSE EVENTS NOTES Tagraxofusp-erzs Targets CD123 (IL-3 receptor)/blastic IR*, ↑LFTs, VLS Delivers a fragment of diphtheria toxin plasmacytoid dendritic cell neoplasm Ziv-aflibercept Targets VEGF by solubilized VEGFR/CRC with chemotherapy after an oxaliplatin regimen ↓Wound healing with fistula, GI perforation, hemorrhage, HBP, DVT, arterial thromboembolism, proteinuria, PRES Note: Data abstracted in part from publicly available U.S. Food and Drug Administration label. All agents in this class have the potential for prominent embryofetal toxicity; use without contraception by female patients of childbearing potential is not recommended. Effective contraception for female partners who are of childbearing potential of patients undergoing treatment should also be considered; use during lactation is also not recommended. Gene products are in capital letters; genes are italicized in capitals. Indications and events of prominent general medical importance include the following: ACE, angiotensin-converting enzyme; ALK, anaplastic lymphoma kinase; ALL, acute lymphoblastic leukemia; AML, acute myeloid leukemia; APL, acute promyelocytic leukemia; ARDS, acute respiratory distress syndrome; AV, atrioventricular; BC, breast cancer; BCRP, breast cancer resistance protein; BP, blood pressure; BRCA, breast cancer gene; BTK, Bruton’s tyrosine kinase; C, constipation; CHF, congestive heart failure; CLL, chronic lymphocytic leukemia; CML, chronic myelogenous leukemia; CNS, can include altered sensorium, cortical and cerebellar signs, dysarthria, altered seizure threshold; Cor, corneal keratopathy, consider pretreatment ophthalmologic exam with prophylactic lubricating eyedrops ± ocular steroids; CRC, colorectal cancer; CrCl, creatinine clearance; CTCL, cutaneous T-cell lymphoma; CYP___, interaction with drugs metabolized by the indicated cytochrome(s) P450; D, diarrhea; DA-H, dose adjust for hepatic dysfunction; DA-R, dose adjust for renal dysfunction; Der, dermatologic toxicity; DLBCL, diffuse large B-cell lymphoma; DVT, deep vein thrombosis; EGFR, epidermal growth factor receptor; FGFR, fibroblast growth factor receptor; FL, follicular lymphoma; GIST, gastrointestinal stromal tumor; GVHD, graft-versus-host disease; H2, histamine receptor antagonist; HBP, high blood pressure; HCC, hepatocellular carcinoma; HER2, human epidermal growth factor receptor 2; HRR, homologous recombination repair; HR, hormone receptor; HUS, hemolytic-uremic syndrome; IDH, isocitrate dehydrogenase; ILD, interstitial lung disease; IR, infusion reaction; IR*, infusion reaction prophylaxis specifically recommended; LFT, liver function tests; LVEF, left ventricular ejection fraction monitor echocardiogram; MDS, myelodysplastic syndrome; MET, hepatocyte growth factor; My, anemia, decrease in white blood cells, platelets, with risk of neutropenic fever, hemorrhage, therefore dose reduce or hold dose for decreased neutrophil or platelet counts unless marrow infiltrated by drug-responsive tumor; N, nausea; Neu, peripheral neuropathy; NSCLC, non-smallcell lung cancer; OC, oral contraceptive; ONJ, osteonecrosis of the jaw; PDGFR, platelet-derived growth factor receptor; PE, pulmonary embolism; Pgp, P-glycoprotein drug resistance protein; Ph, Philadelphia chromosome; Plm, pulmonary; PML, progressive multifocal leukoencephalopathy risk; PPED, palmar-plantar erythrodysesthesia (i.e., hand-foot syndrome); PPI, proton pump inhibitor; PRES, posterior reversible leukoencephalopathy syndrome; Pt, platinating agent; PT, prothrombin time; PTT, partial thromboplastin time; ↑QT, increase of QT interval needs pre- and intratreatment electrocardiogram monitoring and normalizing K+, Mg2+, ionized Ca2+; R, renal injury possible; RCC, renal cell carcinoma; ROS1, receptor tyrosine kinase 1; SLL, small lymphocytic lymphoma; TFT, thyroid function test; TKI, tyrosine kinase inhibitor; TLS, risk of tumor lysis syndrome if brisk response; TOPO___, agent targets the indicated topoisomerase; TSH, thyroid-stimulating hormone; UGT___, drug metabolism by UDPglucuronosyltransferase of the indicated genotype; V, vomiting; VEGFR, vascular endothelial growth factor receptor; Ves, extravasation injury possible; VLS, vascular leak syndrome; VOD, veno-occlusive liver disease. PART 4 Oncology and Hematology fraction of patients with NSCLC. Subsequent studies by clinical oncol­ ogists in an effort to understand the basis of these excellent responses found that the probability of response to the agents was markedly increased in patients with an activating EGFR mutation, and current practice now routinely profiles patients with NSCLC for the presence of sensitizing mutations of EGFR. Side effects were generally accept­ able, consisting mostly of acneiform rash (treated with glucocorticoid creams and clindamycin gel) and diarrhea. Patients with activating mutations who initially responded to gefitinib or erlotinib but who then had progression of the disease then acquired additional mutations in the enzyme, analogous to the mutational variants responsible for imatinib resistance in CML. Subsequent generations of EGFR antago­ nists have activity against more uncommon mutants (osimertinib) or a biochemically irreversible mechanism (dacomitinib). Mutated anaplastic lymphoma kinase (ALK) and activated RET oncogene likewise drive distinct fractions of NSCLCs. Alectinib, ceri­ tinib, crizotinib, and lorlatinib target ALK, but have prominent adverse cardiac, metabolic, and, in the case of lorlatinib, pulmonary events. Selpercatinib targets RET in NSCLCs (and thyroid cancers) but also with the chance of cardiac and liver toxicity. Repotrectinib is active in ROS1 mutant NSCLC. HER2-driven breast cancers may be usefully treated with lapatinib; diarrhea and cardiac dysfunction can occur. Neratinib or tucatinib may also be useful in HER2-positive breast cancers after trastuzumab has ceased to be of value; diarrhea and liver toxicity also require monitor­ ing and management. Alteration of fibroblast growth factor (FGF) signaling can contrib­ ute to the growth of urothelial carcinomas and cholangiocarcinomas. Erdafitinib and pemigatinib, respectively, may be of utility with care­ ful attention to ocular toxicity and hyperphosphatemia; the latter is an “on-target” toxicity of disrupting FGF receptor signaling in the kidney. Likewise, gilteritinib is active against the FMS-like tyrosine kinase-3 (FLT3) mutated in a fraction of poor-prognosis (treated by conventional chemotherapy) acute myeloid leukemias (AMLs). Car­ diac, hepatic, gastrointestinal, and neurologic adverse events can occur, along with “differentiation” of the AML cells with cytokine elaboration and pulmonary side effects, requiring management with steroids and potentially hydroxyurea. The neurotropic tyrosine kinase receptor (NRTK) undergoes trans­ location with fusion to a variety of different partner genes to produce Administer over 1 h, not as push or bolus a family of chimeric proteins in a small fraction of a variety of solid tumors. Larotrectinib and entrectinib may be quite useful in manag­ ing these tumors; indeed, these agents are exemplary of “histology agnostic” agents, where the utility of the drug is not tied to a particular histologic diagnosis, but to the possession of a specific NRTK gene alteration. Neurotoxicity, a long half-life of the agents, and hepatotoxic adverse events are of concern. Neuroregulin 1 (produced by the NRG1 gene) undergoes gene fusions to produce activators of HER family heterodimer signaling, including HER3 and HER4; afatinib covalently binds to all HER family members and has activity in patients with NRG1 gene fusions. RAF/MEK Pathway Antagonists  The RAS proto-oncogene family members (including HRAS, KRAS, and NRAS) act as “switches” to bind GTP in response to activation of receptor tyrosine kinases; RAS-GTP activates the RAF proto-oncogene–derived serine-threonine kinase. RAS mutations of various types result in persistent activation of RAS isoforms, resulting in hyperactivation of RAF and “downstream” kinases, including MEK and MAPK. Sotorasib is a first-in-class inhibi­ tor of KRAS G12C signaling that in early clinical reports has evidence of effecting stable disease in patients with a variety of neoplasm his­ tologies bearing that mutation, with fewer actual responses. Adagrasib also targets KRAS-G12C with a distinct pharmaceutical profile. Neither sotorasib nor adagrasib has activity against wild-type or other RAS mutants, but their discovery marked a milestone, encouraging continu­ ing efforts to produce RAS-directed therapeutics. The BRAF V600E mutation drives a substantial fraction of mela­ nomas and certain NSCLCs and has been detected in certain thyroid tumors, colorectal tumors, hairy cell leukemias, and unusual gliomas. BRAF inhibitors such as dabrafenib, vemurafenib, and encorafenib have activity as single agents in many such tumors but are usually most active when co-administered as “doublets” with the MEK inhibitors trametinib, cobimetinib, and binimetinib, respectively, to promote “shutdown” of RAF/MEK signaling at more than pathway member. Cutaneous adverse events including generally indolent cutaneous second neoplasms, and thromboembolic, cardiac, and ocular toxicity can occur. Multikinase Inhibitors  Agents in this class also target specific macromolecules promoting the viability of tumor cells. They are “small-molecule” ATP site-directed antagonists that inhibit more than one protein kinase and may have value in the treatment of several solid tumors. Drugs of this type with prominent activity against the VEGFR tyrosine kinase have activity in renal cell carcinoma. Sorafenib is a VEGFR antagonist also with activity against the RAF serine-threonine protein kinase, and regorafenib is a closely related drug with value in relapsed advanced colon cancer. Pazopanib also prominently targets VEGFR and has activity in renal carcinoma and soft tissue sarcomas. Sunitinib has anti-VEGFR, anti-PDGFR, and anti-KIT activity. It causes prominent responses and stabilization of disease in renal cell cancers and GISTs. Side effects for agents with anti-VEGFR activity, similar to those of the anti-VEGF antibody bevacizumab, prominently include hypertension, proteinuria, and, more rarely, bleeding and clot­ ting disorders, perforation of scarred gastrointestinal lesions, and pos­ terior leukoencephalopathy, probably reflecting CNS vascular damage. Also encountered are fatigue, diarrhea, and hand-foot syndrome, with erythema and desquamation of the distal extremities, in some cases requiring dose modification, particularly with sorafenib. Other agents in this class include agents such as brigatinib (clinical activity in ALK-dependent NSCLC, but also with anti-EGFR action), entrectinib (clinical activity in NTRK fusion protein diseases, but also in ROS-mutated NSCLC), and fedratinib (clinical activity in myelo­ proliferative neoplasms, but with RET activity in addition to JAK2 and FLT3 antagonism). Agents with anti-RET activity are useful in certain differentiated thyroid cancers and RET-fusion NSCLC. Cyclin-Dependent Kinase Inhibitors  Cyclin-dependent kinases (CDKs) are activated as the result of oncogene pathway activ­ ity, and CDK4 and CDK6 phosphorylate the retinoblastoma (RB) tumor-suppressor gene to allow entry into S-phase. Palbociclib, abe­ maciclib, and ribociclib, selective inhibitors of CDK4 and CDK6, have noteworthy activity in advanced breast cancers also expressing the ER, usually in conjunction with continued efforts to suppress ER signaling, and frequently in conjunction with mammalian target of rapamycin (mTOR) inhibitors. Further clinical investigations in other RB intact tumors may broaden their role. Protein Homeostasis Modulators  The proteasome is a mac­ romolecular complex that degrades misfolded proteins tagged for removal by ubiquitin ligases. Proteasome inhibitors were originally designed as potential anti-inflammatory agents owing to proteasome activity to produce inflammatory cytokines but had unexpected anti­ proliferative activity in a variety of cell types. Proteasome inhibitors have clinical utility in myeloma and lymphoma, where unbalanced synthesis of immunoglobulin components can accumulate after pro­ teasome inhibitor treatment and induce apoptosis or starve cells for amino acids, inducing autophagy. Boronic acid proteasome inhibi­ tors, including bortezomib and ixazomib, cause thrombocytopenia, gastrointestinal dysfunction, and neuropathy. Carfilzomib is a distinct chemotype with attenuated neuropathy but increased incidence of infusion reactions and cytokine release, with attendant risk of cardio­ pulmonary adverse events. Exportin 1 is a nuclear membrane transport protein that is responsi­ ble for normal exit and entry of a variety of nuclear proteins. Selinexor is an inhibitor of exportin action, resulting in abnormal nuclear accu­ mulation of, for example, tumor-suppressor gene products or needed export of other products, such as oncogene products. Useful clinical activity has been seen in myeloma and diffuse large B-cell lymphomas including those arising from previously treated indolent lymphomas. Cytopenias, gastrointestinal distress, and hyponatremia are features of its clinical use. Chromatin-Modifying Agents  Gene function is altered not only by mutation of DNA structure but also by “epigenetic” mechanisms that alter the capacity of DNA to be transcribed or interact with regu­ latory proteins in the nucleus including transcription factors. Initial epigenetic approaches to modulate gene expression extended from the observation that 5′azacytidine and decitabine are misincorporated into DNA and then scavenge DNA methyl transferase to disable DNA methylation of cytosine near gene promoter regions and thus alter their transcription. This “hypomethylation” causes differentiation of AML cells with notably less host toxicity than higher concentrations of these agents or indeed cytosine arabinoside, which does not have prominent hypomethylation activity. Histone deacetylase inhibitors alter the histone protein “packing” density of chromatin and induce global changes in expression of cell cycle regulatory proteins. Vorinostat, belinostat, and romidepsin are useful in cutaneous and peripheral T-cell lymphomas; panobinostat has activity in multiple myeloma. The agents are generally well toler­ ated but with the potential for cytopenias. The histone methyltrans­ ferase inhibitor tazemetostat is a first-in-class inhibitor of histone methyltransferase with unique activity in epithelioid sarcoma owing to its modulation of transcriptional mechanisms unique to that tumor and, recently, in certain follicular lymphomas. Transcription Factor Modulation  Distinct from hormone receptor agonists and antagonists, which as previously described mod­ ulate transcription factor activity by affecting the binding of endog­ enously produced ligands, such as androgens and estrogens, tretinoin (all-trans-retinoic acid) binds to the fusion protein PML-RARα pro­ duced as a result of the t(15,17) chromosomal translocation that under­ lies the pathogenesis of most cases of acute promyelocytic leukemia (APL). PML-RARα functions as transcriptional co-repressor of normal granulocyte maturation; inhibiting the repressor leads to clinical value in the curative treatment of APL. Adverse events include typical symp­ toms of hypervitaminosis A, including skin dryness, cheilitis, increased intracranial pressure, and the development of a “leukemia differentia­ tion syndrome” marked by fever and lung and other organ infiltration by newly differentiated leukocytes, which usually responds to gluco­ corticoids and hydroxyurea but can be life-threatening. Significantly, the coagulopathy of APL is attenuated. Arsenic trioxide nonspecifically affects PML-RARα and other targets by a redox mechanism, contrib­ uting to APL treatment with tretinoin regimens, but with a narrow therapeutic index particularly related to increase of the QT interval, which must be monitored during treatment, while also being carefully attentive to K+, Mg2+, ionized Ca2+, and other drugs that can alter QT. CHAPTER 78 Principles of Cancer Treatment Belzutifan is a novel agent that antagonizes directly the action of hypoxia-inducible factor 2 (HIF2) α, activated in von Hippel-Lindau (VHL) disease–related neoplasms and many sporadic clear cell renal carcinomas through loss of the VHL ubiquitin ligase tumor-suppressor gene. It is safe, but anemia and hypoxemia may occur. The sonic hedgehog factor pathway is regulated by the WNT ligands acting on smoothened receptors, named in reference to Drosophila mutants in which the pathway was originally revealed. In humans, the pathway acts during embryonic and fetal life and in certain neoplasms, and mediates effects on transcription through Gli proteins. Hedgehog pathway inhibitors sonidegib and vismodegib are useful in nonsurgi­ cally treatable cutaneous basal cell carcinomas, and glasdegib is active in certain AMLs where the pathway is active (see Table 78-7). The notch pathway was likewise first noted in Drosophila and acts in metazoans to signal cell position and motion. Notch receptors respond to their ligands by undergoing endocytosis and processing by a γ-secretase, followed by translocation to the nucleus, and function as specific gene transcription factors. The notch pathway has long been known to be active in hematopoietic tumors, but observation has shown confirmed activity in desmoid tumors, inflammatory mesenchymal tumors with poor evidence of control by conventional cytotoxic agents, by nirogace­ stat, the first γ-secretase inhibitor to enter clinical practice. Cancer Cell Metabolism Modulators  Oncogenic transforma­ tion causes a “rewiring” of cellular metabolism away from oxidative phosphorylation to glycolysis (historically defined as the “Warburg effect” of aerobic glycolysis in animal and human tumors) with atten­ dant tolerance of hypoxia and production of metabolites important for sustaining cell proliferation. Recent clinical studies have defined clinical value from inhibitors of the cell lipid membrane localized phos­ phoinositide-3 (PI3) kinase, mTOR, and extra-mitochondrial isocitrate dehydrogenase isoforms 1 and 2. mTOR is a kinase whose inhibition was originally discovered as the basis for activity by the immunosuppressant rapamycin, isolated from a soil bacterium (originally obtained from Rapa Nui), which had evidence of antitumor activity in animals as well as decreased T-cell proliferation. Sirolimus as a protein-bound formulation is used for certain soft tissue tumors. Temsirolimus and everolimus are mTOR inhibitors with activity in renal cancers. They produce stomatitis and fatigue; some hyperlipidemia (10%) and myelosuppression (10%); and rare lung toxicity and immunosuppression in regimens used clinically. Everolimus is also useful in patients with hormone receptor–positive breast cancers displaying resistance to hormonal inhibition and in certain neuroendocrine and brain tumors, the latter arising in patients with sporadic or inherited mutations in the pathway activating mTOR. PI3 kinase is activated by numerous oncogenic tyrosine kinases to ultimately cause a cascade of metabolic alterations including increased glucose uptake and activation of mTOR isoforms, which selectively increase translation efficiency of key regulators of cell cycle progression and protein synthetic capacity. Isoform-specific PI3 kinase inhibitors are of increasing importance in breast cancers with mutated PI3Kα (alpelisib; hyperglycemia and cutaneous eruptions can occur) or owing to selective use of PI3Kδ by lymphoid tissues in lymphomas (idelalisib, copanlisib, and duvelisib). Isocitrate dehydrogenase (IDH) inhibitors (ivosidenib specific for IDH1 and enasidenib specific for IDH2) have activity in tumors with IDH mutants (AML, cholangiocarcinomas) that generate the “onco­ metabolite” 2-hydroxyglutarate, which alters DNA and histone meth­ yltransferase activity. The drugs thus function indirectly as epigenetic chromatin modulating agents through effects on cellular metabolism. Vorasidenib, an IDH1/2 inhibitor with very favorable distribution across the blood-brain barrier, is in very advanced stages of develop­ ment for certain brain tumors with IDH mutations. DNA Repair Pathway Modulators  DNA repair systems act physiologically to lessen the impact of environmental genomic damag­ ing agents and influence the susceptibility to certain chemotherapy agents. DNA repair enzyme mutations underlie inherited cancer sus­ ceptibility syndromes such as mutated BRCA tumor-suppressor gene– associated breast and ovarian cancers, among others. PART 4 Oncology and Hematology Laboratory investigations revealed that poly-ADP ribose poly­ merase (PARP) acts as a synthetic lethal gene with mutations in the homologous recombination repair pathway, including the BRCA gene. PARP responds to detection of DNA lesions by creating chains of poly-ADP, which serve as scaffolds for the localization of DNA repair proteins still active even with mutated BRCA isoforms. However, with­ out PARP activity, the scaffolds cannot form, and the DNA damage becomes lethal. This observation immediately suggested the potential utility of PARP inhibitors (e.g., olaparib) as treatments potentially useful for BRCA-induced tumors. Recently, PARP inhibitor utility has been extended to tumors that do not harbor BRCA mutations but have given evidence of responding to platinum drugs, as a way of extending the useful effect of the chemotherapy treatment. This finding under­ scores the likelihood that sensitivity to DNA-directed cytotoxic drugs on the part of a tumor is at least in part related to the drugs’ ability to take advantage of a sensitizing effect of a tumor’s endogenous DNA repair capacity. Miscellaneous Targeted Therapies  High-affinity binding to receptors on tumor cells can target toxic agents besides drugs to tumor cells, exemplified by the IL-3–diphtheria toxin fusion protein tagraxofusp-erzs, targeting the IL-3 receptor (CD123) and useful in blastic plasmacytoid dendritic cell neoplasms (Table 78-7). Capillary leak syndrome induced due to adventitious “off-target” delivery of the toxin component requires careful monitoring of fluid balance to avoid pulmonary dysfunction in particular. The somatostatin receptor conjugated to a chelate of 177-lutetium can deliver targeted radiation to gastroenterohepatic endocrine neoplasms expressing that receptor. Acutely, release of vasoactive and locally acting hormonal components from dying tumor cells and myelosuppression can occur. Renal dam­ age and the risk of second hematopoietic tumors can complicate con­ tinuing use of the agent. Likewise, 177-lutetium can be delivered via conjugation to a ligand of prostate-specific membrane antigen (PSMA) in the treatment of hormone-resistant prostate cancer. Ziv-aflibercept is not an antibody, but a solubilized VEGF receptor VEGF binding domain, and therefore may have a distinct mechanism of action from bevacizumab but with similar side effects. RESISTANCE TO CANCER TREATMENTS Resistance mechanisms to the conventional cytotoxic agents were initially characterized in the late twentieth century as defects in drug uptake, metabolism, or export by tumor cells. The multidrug resistance (MDR) gene, encoding P-glycoprotein (Pgp), is prototypic of trans­ port proteins that efficiently excrete many drugs from tumor cells; no clinically useful modulator of this process has yet emerged. Drug- metabolizing enzymes such as cytidine deaminase are upregulated in resistant tumor cells, and this is the basis for so-called “high-dose cytarabine” regimens in the treatment of leukemia. Another resistance mechanism defined during this era involved increased expression of a drug’s target, exemplified by amplification of the dihydrofolate reduc­ tase gene, in patients who had lost responsiveness to methotrexate, or mutation of topoisomerase II in tumors that relapsed after topoisom­ erase II modulator treatment. A second class of resistance mechanisms involves loss of the cellular apoptotic mechanism activated after the engagement of a drug’s target by the drug. This occurs in a way that is heavily influenced by the biol­ ogy of the particular tumor type. For example, decreased alkylguanine alkyltransferase expression defines a subset of glioblastoma patients with the prospect of enhanced benefit from treatment with temozolo­ mide but has no value in predicting benefit from temozolomide in epithelial neoplasms. Likewise, ovarian cancers resistant to platinating agents have decreased expression of the proapoptotic gene BAX. A related class of resistance mechanisms emerged from sequencing of the targets of agents directed at oncogenic kinases, revealing mutated targets, as described previously (e.g., p210bcr-ablT315I). This reflects the phenomenon of tumor heterogeneity with distinct populations of sub­ clones that arise in a tumor during the process of carcinogenesis. These subclones share to variable degrees mutations that may promote the growth of some subclones but that are absent or are no longer relevant to the growth of other subclones. This general mechanism of resis­ tance is emerging as a basis for limited value of clinical responses to sotorasib, where sequencing of tumor DNA after clinical resistance has documented “treatment-emergent” mutations in KRAS itself as well as alterations in other proto-oncogenes and their targets. Really useful targeted therapies address a “driver mutation” present in all subclones. Finally, other mechanisms of resistance to targeted agents include the upregulation of alternate means of activating the pathway targeted by the agent. Thus, melanomas initially responsive to BRAF V600E antagonists such as vemurafenib may reactivate RAF signaling by employing variant isoforms that can bypass the drug. Likewise, inhibi­ tion of HER2/neu signaling in breast cancer cells can lead to the emer­ gence of variants with distinct ways of activating downstream effectors such as PI3 kinase. Mechanisms of resistance to immune checkpoint inhibitors such as nivolumab and ipilimumab have not been well defined, but initial characterization of tumors resistant to these agents demonstrates alterations in antigen presentation pathways, concordant with the basis for checkpoint inhibitor action. SUPPORTIVE CARE DURING CANCER TREATMENT ■ ■MYELOSUPPRESSION Most cytotoxic chemotherapeutic agents affect bone marrow function. Polymorphonuclear leukocytes (PMNs; t1/2 = 6–8 h), platelets (t1/2 = 5–7 days), and red blood cells (RBCs; t1/2 = 120 days) have most, less, and least susceptibility, respectively, to usually administered cytotoxic agents. Maximal neutropenia occurs 6–14 days after conventional doses of anthracyclines, antifolates, and antimetabolites. Alkylating agents differ from each other in the timing of cytopenias. Nitrosoureas, DTIC, temozolomide, and procarbazine can display delayed marrow toxicity, first appearing 6 weeks after dosing. Complications of myelosuppression relate to the missing cells’ func­ tion. Febrile neutropenia refers to the clinical presentation of fever TABLE 78-8  Indications for the Clinical Use of G-CSF or GM-CSF Preventive Uses With the first cycle of chemotherapy (so-called primary CSF administration)   Not needed on a routine basis   Use if the probability of febrile neutropenia is ≥20%   Use if patient has preexisting neutropenia or active infection   Age >65 years treated for lymphoma with curative intent or other tumors treated by similar regimens   Poor performance status   Extensive prior chemotherapy   Dose-dense regimens in a clinical trial or with strong evidence of benefit With subsequent cycles if febrile neutropenia has previously occurred (so-called secondary CSF administration)   Not needed after short-duration neutropenia without fever   Use if patient had febrile neutropenia in previous cycle   Use if prolonged neutropenia (even without fever) delays therapy Therapeutic Uses Afebrile neutropenic patients   No evidence of benefit Febrile neutropenic patients   No evidence of benefit   May feel compelled to use in the face of clinical deterioration from sepsis, pneumonia, or fungal infection, but benefit unclear In bone marrow or peripheral blood stem cell transplantation   Use to mobilize stem cells from marrow   Use to hasten myeloid recovery In acute myeloid leukemia   G-CSF of minor or no benefit   GM-CSF of no benefit and may be harmful In myelodysplastic syndromes   Not routinely beneficial   Use intermittently in subset with neutropenia and recurrent infection What Dose and Schedule Should Be Used? G-CSF: 5 mg/kg per day subcutaneously GM-CSF: 250 mg/m2 per day subcutaneously Pegfilgrastim: one dose of 6 mg 24 h after chemotherapy When Should Therapy Begin and End? When indicated, start 24–72 h after chemotherapy Continue until absolute neutrophil count is 10,000/μL Do not use concurrently with chemotherapy or radiation therapy Abbreviations: CSF, colony-stimulating factor; G-CSF, granulocyte colony-stimulating factor; GM-CSF, granulocyte-macrophage colony-stimulating factor. Source: From the American Society of Clinical Oncology: J Clin Oncol 24:3187, 2006. and <1500 granulocytes/μL. Management of febrile neutropenia is considered in Chap. 79. Colony-stimulating factors (CSFs) are used to augment bone marrow production of PMNs. The American Society of Clinical Oncology has developed practice guidelines for the use of granulocyte CSF (G-CSF) and GM-CSF (Table 78-8). Dangerous degrees of thrombocytopenia do not frequently compli­ cate the management of patients with solid tumors receiving cytotoxic chemotherapy (with the possible exception of certain carboplatincontaining regimens), but they are frequent in patients with hemato­ logic neoplasms. Severe bleeding related to thrombocytopenia occurs with increased frequency at platelet counts <20,000/μL in patients with acute leukemia and <10,000/μL in patients with solid tumors and is prevalent at counts <5000/μL. The precise “trigger” point at which to transfuse patients has been defined as a platelet count of 10,000/μL or less in patients without medical comorbidities that may increase the risk of bleeding. This issue is important not only because of the costs of frequent transfusion but also because unnecessary platelet transfusions expose the patient to the risks of allosensitization and loss of value from subsequent transfu­ sion, as well as the infectious and hypersensitivity risks inherent in any transfusion. Careful review of medication lists to prevent exposure to nonsteroidal anti-inflammatory agents and maintenance of clotting factor levels adequate to support near-normal prothrombin and partial thromboplastin time tests are important in minimizing the risk of bleeding in the thrombocytopenic patient. Anemia associated with chemotherapy can be managed by transfu­ sion of packed RBCs. Transfusion is not undertaken until the hemo­ globin falls to <80 g/L (8 g/dL), compromise of end-organ function occurs, or an underlying condition (e.g., coronary artery disease) calls for maintenance of hemoglobin >90 g/L (9 g/dL). Randomized trials in certain tumors have raised the possibility that erythropoietin (EPO) use may promote tumor cell survival. ■ ■NAUSEA AND VOMITING The most common side effect of chemotherapy administration is nausea, with or without vomiting. Nausea may be acute (within 24 h of chemotherapy), delayed (>24 h), or anticipatory of the receipt of chemotherapy. Highly emetogenic drugs (risk of emesis >90%) include DTIC, cyclophosphamide at >1500 mg/m2, and cisplatin; moderately emetogenic drugs (30–90% risk) include carboplatin, cytosine arabi­ noside (>1 g/m2), ifosfamide, conventional-dose cyclophosphamide, and anthracyclines; low-risk (10–30%) agents include 5-FU, taxanes, etoposide, and bortezomib, with minimal risk (<10%) afforded by treatment with antibodies, bleomycin, busulfan, fludarabine, and vinca alkaloids. CHAPTER 78 Principles of Cancer Treatment Serotonin antagonists (5-HT3) and neurokinin 1 (NK1) receptor antagonists are useful in “high-risk” chemotherapy regimens. The combination acts at both peripheral gastrointestinal and CNS sites that control nausea and vomiting. For example, the 5-HT3 blocker dolasetron, 100 mg intravenously or orally; dexamethasone, 12 mg; and the NK1 antagonist aprepitant, 125 mg orally, are combined on the day of administration of severely emetogenic regimens, with repeti­ tion of dexamethasone (8 mg) and aprepitant (80 mg) on days 2 and 3 for delayed nausea. Alternate 5-HT3 antagonists include ondansetron, given as 0.15 mg/kg intravenously for three doses just before and at 4 and 8 h after chemotherapy; palonosetron at 0.25 mg over 30 s, 30 min before chemotherapy; and granisetron, given as a single dose of 0.01 mg/kg just before chemotherapy. Emesis from moderately emetic chemotherapy regimens may be prevented with a 5-HT3 antagonist and dexamethasone alone for patients not receiving doxorubicin and cyclophosphamide combinations; the latter combination requires the 5-HT3/dexamethasone/aprepitant on day 1, but aprepitant alone on days 2 and 3. Emesis from low-emetic-risk regimens may be prevented with 8 mg of dexamethasone alone or with non-5-HT3, non-NK1 antagonist approaches including the following. Antidopaminergic phenothiazines act directly at the chemoreceptor trigger zone (CTZ) in the brainstem medulla and include prochlor­ perazine (Compazine), 10 mg intramuscularly or intravenously, 10–25 mg orally, or 25 mg per rectum every 4–6 h for up to four doses; and thiethylperazine, 10 mg by potentially all of the above routes every 6 h. Haloperidol is a butyrophenone dopamine antagonist given at 1 mg intramuscularly or orally every 8 h. Metoclopramide acts on peripheral dopamine receptors to augment gastric emptying and is used in high doses for highly emetogenic regimens (1–2 mg/kg intravenously 30 min before chemotherapy and every 2 h for up to three additional doses as needed); intravenous doses of 10–20 mg every 4–6 h as needed or 50 mg orally 4 h before and 8 and 12 h after chemotherapy are used for moderately emetogenic regimens. 5-9-Tet­ rahydrocannabinol (Marinol) is a rather weak antiemetic compared to other available agents, but it may be useful for persisting nausea and is used orally at 10 mg every 3–4 h as needed. Olanzapine, an “atypical antipsychotic” acting at multiple neurotransmitter receptors, may be of value, most clearly in cases refractory to the measures described above. Some practice guidelines have endorsed its earlier use in adults receiv­ ing highly emetogenic chemotherapy regimens in combination with an NK1 antagonist plus a 5-HT3 antagonist plus dexamethasone. # 08 - 79 Infections in Patients with Cancer ### 79 Infections in Patients with Cancer ■ ■DIARRHEA Similar to the vomiting syndromes, chemotherapy-induced diarrhea may be immediate or can occur in a delayed fashion up to 48–72 h after the drugs. Careful attention to maintained hydration and elec­ trolyte repletion, intravenously if necessary, along with antimotility treatments such as “high-dose” loperamide (4 mg at the first occur­ rence of diarrhea, with 2 mg repeated every 2 h until 12 h without loose stools, not to exceed a total daily dose of 16 mg), are appropriate. Octreotide (100–150 μg), a somatostatin analogue, or intralumenally acting opiate-based preparations may be considered for patients not responding to loperamide. ■ ■MUCOSITIS Irritation and inflammation of the mucous membranes (mucositis) particularly afflicting the oral and anal mucosa, but potentially involv­ ing the entire gastrointestinal tract, may accompany cytotoxic chemo­ therapy. Topical therapies, including anesthetics and barrier-creating preparations, may provide symptomatic relief in mild cases. ■ ■ALOPECIA Chemotherapeutic agents vary widely in causing alopecia, with anthra­ cyclines, alkylating agents, and topoisomerase inhibitors reliably causing near-total alopecia when given at therapeutic doses. Antime­ tabolites are more variably associated with alopecia. Psychological sup­ port and the use of cosmetic resources are to be encouraged. “Chemo caps” that reduce scalp temperature to decrease the degree of alopecia are controversial during treatment with curative intent of neoplasms, such as leukemia or lymphoma, or in adjuvant breast cancer therapy. The richly vascularized scalp can certainly harbor micrometastatic or disseminated disease. PART 4 Oncology and Hematology ■ ■GONADAL DYSFUNCTION AND PREGNANCY All cancer treatments described in this chapter should be regarded as potentially injurious to the developing fetus and to newborns via lactation. However, there are gradations to the degree of reproductive harm. All agents tend to have increased risk of adverse outcomes when administered during the first trimester, and strategies to delay chemo­ therapy, if possible, until after this milestone should be considered if the pregnancy is to continue to term. Patients in their second or third trimester can be treated with most regimens for the common neo­ plasms afflicting women in their childbearing years, with the excep­ tion of antimetabolites, particularly antifolates, which have notable teratogenic or fetotoxic effects throughout pregnancy. The need for anticancer chemotherapy per se is infrequently a clear basis to recom­ mend termination of a concurrent pregnancy, although each treatment strategy in this circumstance must be tailored to the individual needs of the patient. Cessation of ovulation and azoospermia reliably result from regi­ mens that contain alkylating agents and topoisomerase poison. The duration of these effects varies with age and sex. Sperm banking before treatment may be considered. Females experience amenorrhea with anovulation after alkylating agent therapy; egg preservation may be considered but may delay inception of urgent treatment. Recovery of normal menses is frequent if treatment is completed before age 30, but patients are unlikely to recover menses after age 35. Even those who regain menses usually experience premature menopause. Because the magnitude and extent of decreased fertility can be difficult to predict, patients should be counseled to maintain effective contraception, preferably by barrier means, during and after therapy. Resumption of efforts to conceive should be considered in the context of the patient’s likely prognosis. Hormone replacement therapy should be undertaken in women who do not have a hormonally responsive tumor. For patients who have had a hormone-sensitive tumor primarily treated by a local modality, conventional practice would counsel against hormone replacement, but this issue is under investigation. ■ ■PALLIATIVE AND SUPPORTIVE CARE An important perspective the primary care provider may bring to patients and their families facing incurable cancer is that, given the limited value of chemotherapeutic approaches at some point in the natural history of most metastatic cancers, palliative care or hospice-based approaches, with meticulous and ongoing attention to symptom relief and with family, psychological, and spiritual support, should receive prominent attention as a valuable therapeutic plan (Chaps. 13 and 73). Optimizing the quality of life rather than attempting to extend it becomes a valued intervention. Patients facing the impending progression of disease in a life-threatening way frequently choose to undertake toxic treatments of little to no poten­ tial value, and support provided by the primary caregiver in accessing palliative and hospice-based options in contrast to receiving toxic and ineffective regimens can be critical in providing a basis for patients to make sensible choices. Late effects of cancer and its treatment are reviewed in Chap. 100. ■ ■FURTHER READING Ascione L et al: Predicting response to antibody drug conjugates: A focus on antigens’ targetability. Oncologist 28:944, 2023. Chabner BA, Longo DL: Cancer Chemotherapy, Immunotherapy, and Biotherapy; Principles and Practice, 7th ed. Philadelphia, Wolters Kluwer, 2025. Emadi A, Karp JE: Cancer Pharmacology: An Illustrated Manual of Anticancer Drugs, 2nd ed. New York, Springer Publishing Co., 2024. Federman N: Molecular pathogenesis of desmoid tumor and the role of γ-secretase inhibition. NPJ Precis Oncol 6:62, 2022. Hesketh PJ et al: Antiemetics: American Society of Clinical Oncology clinical practice update. J Clin Oncol 35:3240, 2017. Kaelin WG Jr: Von Hippel-Lindau disease: Insights into oxygen sens­ ing, protein degradation, and cancer J Clin Invest 132:e162480, 2022. Morad G et al: Hallmarks of response, resistance, and toxicity to immune checkpoint blockade. Cell 184:5309, 2021. Nikanjam M et al: Liquid biopsy: Current technology and clinical applications. J Hematol Oncol 15:131, 2022. Puzanov I et al: Managing toxicities associated with immune check­ point inhibitors: Consensus recommendations from the Society for Immunotherapy of Cancer (SITC) Toxicity Management Working Group. J Immunother Cancer 5:95, 2017. Rosen N, Longo DL: Targeting oncogenic RAS protein. N Engl J Med 387:184, 2022. Sartor O et al: Lutetium-177–PSMA-617 for metastatic castrationresistant prostate cancer. N Engl J Med 385:1091, 2021. Brahm H. Segal, Juan C. Gea-Banacloche Infections in Patients with Cancer GENERAL CONCEPTS Infection is an important complication of cancer and cancer therapy and drives excess hospitalization and mortality. Prevention, diagnosis, and treatment of infection increases survival and improves quality of life. In this regard, the infectious diseases consultant works col­ laboratively with multiple stakeholders to prevent infection and to effectively diagnose and treat infections when they occur. Cornerstones of infection prevention are compliance with standard infection control guidelines, limiting exposure to pathogens, vaccination of patients and caregivers, and targeted use of antimicrobial prophylaxis. Although there have been substantial improvements in diagnostic modalities for infection including molecular and antigen-based diagnostics, the infectious diseases physician is frequently confronted with patients with suspected infection (e.g., neutropenic fever, lung lesions observed by imaging) without a definitive diagnosis. In addition, infectious and noninfectious disorders may have overlapping manifestations, such as pneumonia versus drug-related pneumonitis and fever from infection versus cancer-associated fever. Given the broad differential diagnosis, aggressive diagnostic evaluation including biopsies may be required. Sometimes, empirical therapy must be administered based on the most likely or dangerous infections; these situations are common in patients with hematologic malignancies in whom an invasive tissue diagnosis may be unsafe due to thrombocytopenia. We provide recommendations for therapy of both documented and suspected infections. Specific treatment plans should consider several factors, such as evidence of clearance of infection, whether a persistent nidus exists (e.g., abscess or infectious phlebitis), the specific pathogen, and the immune status of the patient. A general principle of therapy is that longer courses are required in patients with persistent and severe immunocompromise (e.g., prolonged neutropenia in patients with acute leukemia or myelodysplastic syndrome). An individualized approach to the diagnosis and management of infections that is tailored to overall goals of care is recommended. For example, in the setting of uncon­ trolled malignancy (e.g., recurrent cholangitis from obstructive pan­ creatic or biliary cancers or secondary infections of tumor from bowel fistulization), source control by surgery or catheter drainage may not be feasible, and antibiotics may be used palliatively for patient comfort and to avoid unnecessary hospitalizations rather than to cure an infection. We will address the risk factors for infections and the preventive measures that may be adopted based on those risk factors. Most spe­ cific infections have dedicated chapters, and readers are advised to access those for in-depth discussions. We will focus here on infections associated with (or caused by) the treatment of cancer. Chemotherapyinduced neutropenia is the most important etiology, and the manage­ ment of neutropenic fever will be discussed in detail. We will also discuss infections associated with new treatment modalities, including biologics, immunotherapy, and cellular therapies. Infections related to hematopoietic stem cell transplant (HCT) are discussed in Chap. 148. RISK FACTORS FOR INFECTION IN PATIENTS WITH CANCER When evaluating patients with cancer and suspected infection, it is important to consider the major factors—both intrinsic and treatmentassociated—that predispose to infection. This knowledge, in turn, guides the differential diagnosis, diagnostic evaluation, and initial therapy. ■ ■RISK FACTORS INTRINSIC TO THE CANCER These are the direct consequence of the cancer. In the case of solid tumors, the most obvious risk factor for infection relates to obstruc­ tion. As examples, lung tumors that obstruct the airway predispose to postobstructive pneumonia, obstructive pancreatic and biliary tumors predispose to cholangitis, and tumors that result in obstructive uropa­ thy predispose to urinary tract infections. Tumors of the head and neck increase the risk of local infection and aspiration pneumonia. Gastro­ intestinal tumors can present with obstruction and local abscess pro­ duction by enteric flora and bloodstream infection (e.g., bloodstream infection by Streptococcus gallolyticus or Clostridium septicum in colon cancer). Direct invasion through the colonic mucosa is associated with local abscess formation and sepsis by enteric flora. Some hematologic malignancies are associated with specific immune deficits. Acute leukemia and myelodysplastic syndrome can manifest with pancytopenia at diagnosis. Patients may have a high burden of circulating leukemic cells and lack normal circulating neutrophils. Some patients with myelodysplastic syndrome or acute myelogenous leukemia (AML) have mutations that are associated marrow failure and immunodeficiency. For example GATA2 deficiency is associated with major viral, bacterial, and fungal infections as well as hematological malignancies and solid tumors. Multiple myeloma and chronic lym­ phocytic leukemia are associated with impaired immunoglobulin pro­ duction that can manifest with recurrent sinopulmonary infections and poor antibody responses to both prior infections and vaccination. Case series suggest that patients with hairy cell leukemia are at increased risk of nontuberculous mycobacterial infections. T cell–associated leuke­ mias and lymphomas can be associated with human T lymphotropic virus 1 (HTLV1) and have T cell impairment and opportunistic infec­ tions by Pneumocystis jirovecii, Cryptococcus neoformans, tuberculosis, or disseminated strongyloidiasis. ■ ■RISK FACTORS ASSOCIATED WITH CANCER THERAPY There has been a dramatic expansion in cancer therapeutics, most of which influence host defense against infections (Table 79-1). Broadly speaking, cancer therapy can compromise either or both the physical barriers and immune responses that protect from infection. Examples of physical barrier disruption include central venous catheters, surgical wounds that can be a portal of entry for skin microbes, and disruption of the lymphatic drainage after mastectomy and lymphadenectomy for breast cancer. The mucosal lining of the gastrointestinal tract, respiratory tract, and other luminal surfaces constitutes the first line of host defense, both as a physical barrier and by secretion of a variety of antimicrobial products, such as immunoglobulin A (IgA), lactoferrin, and anti­ microbial peptides. Standard nonselective cytotoxic agents have the combined effect of both pancytopenia and mucosal disruption that predispose to infection. Radiation is sometimes administered concur­ rently with chemotherapy and, depending on the location of the radia­ tion field, can cause significant mucosal injury. Antineoplastic agents that inhibit specific pathway(s) that drive tumor cell progression are considered targeted, but they also impair specific components of the immune system whose function relies on these same pathways. For example, the anti-tumor activity of Bruton tyrosine kinase inhibitors against B-cell malignancies is by inhibiting the B-cell receptor signaling cascade, but this property can have broad immune effects that increase the risk of viral and fungal infections. CHAPTER 79 Infections in Patients with Cancer Chemotherapy-Induced Neutropenia  It has been recognized for more than 50 years that the duration and degree of neutropenia drive susceptibility to infections in patients with cancer. Cytotoxic regi­ mens that result in prolonged neutropenia also deplete other immune cells (e.g., circulating monocytes and lymphocytes) and commonly cause mucosal injury. The risk of infection is proportional to the degree of neutropenia once the absolute neutrophil count (ANC) becomes <1000/µL. For example, standard induction chemotherapy with anthracycline plus cytarabine for AML causes prolonged neutropenia and severe mucositis. The combination of prolonged neutropenia and mucositis predisposes these patients to gastrointestinal tract infections that include ulcerations of the oral mucosa, neutropenic enterocolitis (typhlitis), and perirectal infections, as well as bloodstream infec­ tions by gastrointestinal flora such as viridians group streptococci, enterococci, and Enterobacterales. Reactivation of oral mucosal herpes simplex virus (HSV) is another common complication of leukemia therapy. Reflecting the fact that Candida species are endogenous gastrointestinal flora, these patients are also at risk for candidemia and chronic disseminated candidiasis. Patients with more prolonged neutropenia (e.g., ANC <500/µL for ≥2 weeks) are at risk for invasive aspergillosis and other molds. Refractory and relapsed acute leukemia further increase the risk of invasive fungal disease (Table 79-1). Antimicrobial prophylaxis tailored to the underlying immune defects has been shown to be effective in several settings, and it should be used with knowledge of the proven benefits and the direct and indirect toxicities (prevention of fever differs from prevention of infection and prolongation of survival), as well as the limitations of the available evidence. As an example, prophylaxis with a fluoroquinolone like levofloxacin should be considered in adults with prolonged neu­ tropenia (e.g., ANC <500/µL for ≥7 days). Multiple studies have shown decreased frequency of neutropenic fever and fewer documented infec­ tions, and meta-analyses suggest a survival benefit. In patients with AML receiving induction chemotherapy, prophylaxis with posacon­ azole was associated with less invasive fungal disease (IFD) and a survival benefit, so posaconazole is frequently recommended as prophylaxis in patients with profound, prolonged neutropenia. It is plausible that isavuconazole may be equally effective, but its efficacy in this setting has not been demonstrated. TABLE 79-1  Immune Defects and Associated Infections in Cancer Patients HOST DEFENSE DEFECT PREDOMINANT PATHOGENS PATIENTS WITH CANCER AT GREATEST RISK Neutropenia (ANC <500/µL) Gram-negative and gram-positive bacteria Cytotoxic chemotherapy, underlying hematologic malignancy (e.g., myelodysplasia, acute leukemia) Prolonged (≥10 days), profound neutropenia (ANC <100/µL) Increased risk of bacterial infections Candidemia Invasive aspergillosis and other molds HSV reactivation Respiratory viral infections T cell immunodeficiency Common bacterial infections Intracellular bacteria (e.g., Listeria monocytogenes, Salmonella species) Nocardia species Tuberculosis and NTM Respiratory viral infections Reactivation of herpes viruses (HSV, VZV); with severe impairment: CMV, EBV-associated lymphoproliferative disease; HHV-6-associated marrow suppression or encephalopathy, and HHV-8-associated malignancies) Mucosal candidiasis Pneumocystis jirovecii Dimorphic fungal infections (e.g., histoplasmosis, coccidioidomycosis) Cryptococcus neoformans Invasive aspergillosis and other molds Toxoplasmosis Strongyloides hyperinfection PART 4 Oncology and Hematology B cell immunodeficiency Encapsulated bacteria (Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis) Respiratory viral infections Reactivation of HSV and VZV Reactivation of HBV PML (reactivation of JC virus) Splenectomy and functional asplenia Encapsulated bacteria (can result in life-threating sepsis) Malaria, babesiosis Mucosal injury Localized infections by oral and GI flora (e.g., dental infections, neutropenic enterocolitis, perianal infection) Bacteremia (coliforms, oral streptococci, enterococci, anaerobes; can be polymicrobial) Systemic corticosteroids Broad suppressive effect on innate and adaptive immunity related to dose and duration of treatment Increased risk of common bacterial and viral infections Prolonged high-dose corticosteroids (e.g., prednisone equivalent to ≥20 mg/day for ≥28 days) increases risk of multiple opportunistic pathogens associated with impaired T cell immunity (e.g., Pneumocystis jirovecii) Abbreviations: AIDS, acquired immunodeficiency syndrome; ANC, absolute neutrophil count; BTK, Bruton tyrosine kinase; CAR, chimeric antigen receptor; CMV, cytomegalovirus; EBV, Epstein-Barr virus; GVHD, graft-versus-host disease; HBV, hepatitis B virus; HHV, human herpes virus; HSV, herpes simplex virus; MDS, myelodysplastic syndrome; NTM, nontuberculous mycobacteria; PML, progressive multifocal leukoencephalopathy; TNF, tumor necrosis factor; VZV, varicella-zoster virus. Corticosteroids  Corticosteroids are part of several chemotherapy regimens used in hematologic malignancies, such as in acute lymphoid leukemias, lymphomas, and multiple myeloma. Patients with brain tumors, both primary and metastatic, are treated with corticoste­ roids to control edema. In addition, corticosteroids are a mainstay of therapy to control inflammatory complications of cancer therapy. For example, immune checkpoint inhibitors are associated with pneumo­ nitis, colitis, and autoimmune endocrinopathies that are treated with corticosteroids, and additional agents such as tumor necrosis factor α blockade when corticosteroids alone are insufficient. Corticosteroids are also used as therapy for graft-versus-host disease (GVHD) fol­ lowing allogeneic stem cell transplantation and for cytokine release syndrome (CRS) following bispecific antibody therapy and adoptive cellular therapy. Induction/reinduction therapy for acute leukemia; pancytopenia from underlying hematologic malignancy; myeloablative conditioning regimens for stem cell transplantation and lymphodepletion for adoptive cellular therapy Underlying hematologic malignancy including primary T cell malignancies AIDS-associated malignancies Corticosteroids, TNF-α blockade Janus kinase inhibitors Purine analogues Alemtuzumab GVHD Lymphodepletion for adoptive cellular therapy Lymphoid malignancies (e.g., chronic lymphocytic leukemia, multiple myeloma) B cell–depleting agents (e.g., rituximab, BTK inhibitors) Stem cell transplantation, particularly with chronic GVHD Bispecific antibodies and adoptive cellular therapy targeted against B cell antigens (e.g., CD19-directed CAR T cell regimens) Functional asplenia in chronic GVHD Cytotoxic chemotherapy that results in both neutropenia and mucosal injury Radiation (e.g., for head and neck tumors or rectal cancer) predisposes to local tissue damage, impaired blood flow, and secondary bacterial infection Corticosteroids are common components of antineoplastic regimens for hematologic cancers (e.g., for acute lymphoblastic leukemia, lymphomas, and multiple myeloma) and are administered concurrently with other immunosuppressive therapies Other common indications for corticosteroids are to reduce inflammation from central nervous system tumors and as therapy for immune-related toxicities High-dose corticosteroids have inhibitory effects on multiple com­ ponents of innate and adaptive immunity. The risk of infections is related to their dose and duration, the underlying malignancy, and other immunosuppressive agents that are used concurrently. For exam­ ple, induction therapy for acute lymphoblastic leukemia includes both cytotoxic agents that result in pancytopenia and corticosteroids that cumulatively increase infection risk. Corticosteroids can also decrease signs of infection such as fever and abdominal tenderness. The inhibi­ tory effect of corticosteroids on T cell immunity increases the risk of infections by viruses (e.g., HSV, varicella-zoster virus [VZV]), myco­ bacteria, Nocardia species, and fungal infections, including mucosal candidiasis, dimorphic fungi, and Pneumocystis jirovecii pneumonia (PJP) (Table 79-1). Prophylaxis against Pneumocystis jirovecii with trimethoprim sulfamethoxazole (TMP-SMX) (or an alternative agent if intolerant) is recommended in patients receiving the adult equivalent of prednisone ≥20 mg per day for at least 4 weeks. Radiation  Radiation causes direct tissue damage (including dam­ age to the vasculature) and impairs wound healing. Infectious com­ plications of radiation include local infection and fistulization. As an example, neoadjuvant radiation therapy for rectal tumors increases the risk of surgical site infections. Radiation to the head and neck increases the risk of infections related to the tumor and as a surgical complica­ tion. Osteoradionecrosis of the jaw predisposes to secondary infections of the soft tissue and bone that may require combined prolonged anti­ biotics and surgical removal of dead bone and reconstruction. Splenectomy  Splenectomy may be performed for diagnosis or treatment of cancer. The spleen has several key immune functions including removing of bacteria from blood, antigen presentation to T cells, and housing B cells that are activated and produce antibodies. Functional asplenia is present after splenic irradiation and with chronic GVHD. Asplenic patients are principally at risk for overwhelming sepsis by encapsulated bacteria like Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitidis. Patients should be vaccinated against these pathogens prior to planned splenectomy. Antibiotic pro­ phylaxis (e.g., with penicillin) should be considered for the first 2 years after splenectomy, especially in patients with active malignancy or receiv­ ing immunosuppressive therapy. Asplenic patients with fever should be started promptly on antibiotics active against S. pneumoniae (e.g., ceftriaxone or levofloxacin or moxifloxacin). Vancomycin should be added in areas where high-level penicillin or cephalosporin resistance is common. Asplenic individuals also have increased risk of babesiosis, malaria, and infection with Capnocytophaga canimorsus (associated with animal bites or scratches) and Salmonella spp. B Cell–Depleting Agents  B cell–depleting agents are used as therapy for patients with B cell malignancies, such as B cell lymphomas and chronic lymphocytic leukemia. They are commonly used in com­ bination with other antineoplastic agents. Antibody-based drugs such as rituximab result in prolonged B cell depletion, while Bruton tyrosine kinase (BTK) inhibitors (e.g., ibrutinib) interrupt a key enzyme and B cell activation but have shorter-acting effects. The effects of B cell depletion include increased risk of encapsulated bacteria and respi­ ratory viral infections. Importantly, these patients are likely to have reduced immune responses to vaccination against bacteria and viruses, including influenza, SARS-CoV-2, and hepatitis B. The risk of severe COVID-19 is substantially increased in patients with hematologic malignancies compared with patients with solid tumors, and B cell– depleting agents are associated with increased COVID-19 severity and lack of serologic responses to SARS-CoV-2 infection and vaccination. All patients who will receive B cell–depleting agents should be screened for hepatitis B infection and receive therapy for hepatitis B (e.g., with entecavir or tenofovir alafenamide) for active or prior hepatitis B infection (see Chaps. 350 and 352 on hepatitis viruses and Chap. 208 on human immunodeficiency virus [HIV] infections). Rituximab and other B cell–depleting agents have been associated with progressive multifocal leukoencephalopathy (PML) and PJP, but the magnitude of the effect is difficult to ascertain. In addition, BTK inhibitors can have off-target effects on innate immune cells and increase the risk of other infections, including invasive aspergillosis, particularly when com­ bined with other immunosuppressive agents, such as corticosteroids. Bispecific Antibodies  Bispecific antibodies are engineered to have dual specificity for a T cell antigen (e.g., CD3, a component of the T cell receptor complex) and a tumor antigen with the goal of stimulating T cell killing of tumor cells. When bispecific antibody con­ structs directed against B cell antigens (e.g., blinatumomab, a bispecific antibody against CD3 and the B cell antigen CD19) are used against B cell malignancies, the overall effect is a nonselective depletion of both tumor cells and normal B cells. Importantly, bispecific antibodies are commonly used in patients with refractory hematologic malignancies who already are at high risk for infection based on the underlying can­ cer and prior therapy. Bispecific antibody therapy can result in CRS, characterized by fever and inflammatory organ damage. Treatment of CRS involves high-dose corticosteroids and interleukin 6 (IL-6) block­ ade, which further increases the risk of infections. Adoptive Cellular Therapy  Adoptive cellular therapy (ACT) involves administration of genetically engineered cells targeted to tumor antigens. The most commonly used ACT is chimeric antigen receptor (CAR) T cells, in which autologous T cells are genetically engi­ neered to express a receptor directed against a tumor antigen. Engage­ ment of cells expressing this antigen results in the CAR T cell activation and tumor cell killing. In contrast to bispecific antibodies, current ACT involves lymphodepletion chemotherapy (usually with fludarabine and cyclophosphamide) to deplete immune cells and allow maximal expan­ sion of the engineered T cells. A major goal of immunotherapy is to make ACT more effective for a broad range of solid tumors; however, the current use of ACT largely involves refractory B cell malignancies: lymphoblastic leukemia, lymphomas, and multiple myeloma. Lym­ phodepletion regimens result in pancytopenia, and both neutropenia and lymphopenia can be prolonged (months to years). In the case of standard CD19-directed CAR T cells, B cell depletion is by design; the persistence of CAR T cells is required for antitumor immunity, but it is nonselective, and the duration of global B cell depletion can be for years. ACT can also be complicated by CRS and an immune effector cell–associated neurotoxicity syndrome that can be life-threatening and requires treatment with intensive high-dose corticosteroids often combined with IL-6 blockade. Additional hematologic complications can occur after ACT, such as hemophagocytic lymphohistiocytosis (HLH), which extends pancytopenia and entails additional immuno­ suppressive therapy. CHAPTER 79 Infections in Patients with Cancer Recommendations regarding prophylaxis following ACT are based mainly on extrapolation and expert opinion. These include levofloxa­ cin during neutropenia, TMP-SMX while on systemic corticosteroids or while CD4 count is <200/µL, acyclovir, and perhaps mold-active prophylaxis (e.g., posaconazole) during periods of prolonged neutro­ penia. Recipients of CAR T cells constitute a heterogeneous population due to the effect of multiple previous courses of therapy, sometimes including allogeneic HCT, and prophylaxis should be tailored to the degree of immunosuppression. Cancer and HIV Infection  HIV-associated malignancies include Epstein-Barr virus–associated non-Hodgkin and Hodgkin lymphomas, HHV-8-associated Kaposi sarcoma and primary effusion lymphoma, and human papilloma virus–associated cervical and anal cancer. HIVpositive patients have higher risks of chronic hepatitis B and hepatitis C infections that increase the risk of hepatocellular carcinoma. Patients with HIV infection can also have cancers that are not HIV-associated. A mainstay of cancer management in patients who are HIV-positive is that the antineoplastic regimen must be concurrent with antiretroviral therapy and appropriate prophylactic antimicrobials. The goals of anti­ retroviral therapy are a nondetectable HIV viral load and tolerability of the regimen, which includes monitoring and avoiding drug–drug interactions with antineoplastic chemotherapy. In general, it is recom­ mended to test for HIV and hepatitis B and hepatitis C infection prior to starting antineoplastic therapy. DIAGNOSIS AND MANAGEMENT OF INFECTIONS IN PATIENTS WITH NEUTROPENIA Chemotherapy-induced neutropenia remains the major risk factor for infection in patients with cancer. However, patients with cancer fre­ quently have multiple risk factors for infection, both from the under­ lying malignancy and its treatment. When evaluating patients with neutropenia and suspected infection, it is important to consider these other risk factors in the diagnostic evaluation and therapy (Fig. 79-1). ■ ■NEUTROPENIC FEVER A high proportion of cancer patients who become neutropenic after receiving chemotherapy develop fever. The standard definition of neu­ tropenic fever (NF) is a single oral temperature ≥38.3°C or a tempera­ ture of ≥38.0°C sustained over 1 h, with an absolute neutrophil count A B FIGURE 79-1  Multiple pulmonary infections in a patient with acute myelogenous leukemia (AML). A patient with AML in remission after reinduction therapy with cytarabine, granulocyte colony-stimulating factor, and fludarabine (FLAG) presented with fever and neutropenia. A chest CT demonstrated diffuse pulmonary infiltrates (A). Bronchoalveolar lavage (BAL) was unrevealing except for positive PCR for Pneumocystis jirovecii, and trimethoprim-sulfamethoxazole was instituted. After 11 days of appropriate treatment (B), a repeat CT showed resolution of the infiltrates but a conspicuous, dense, well-circumscribed pulmonary nodule that had not been appreciated initially. Targeted BAL of the left lower lobe was positive for galactomannan, providing the diagnosis of probable invasive aspergillosis. The initial BAL had been of the right middle lobe only. Immunocompromised patients may have several infections simultaneously, and cancer patients often accumulate risk factors for infection during their treatment. PART 4 Oncology and Hematology (ANC) of <500 cells/µL, or an ANC that is expected to decrease to <500 cells/µL over the next 48 h. During neutropenia localizing signs and symptoms of infection may be subtle or altogether lacking, and infections may progress very quickly. These two basic features mandate early initiation of empiri­ cal antibacterial agents in neutropenic patients whenever infection is suspected. Although fever is the most common sign of infection, it is not the only one, and similar management should be used whenever infection is suspected in a neutropenic patient, such as in the presence of otherwise unexplained pain, tenderness, or erythema potentially secondary to infection. NF is considered infectious in origin, but an infection is identified in only a minority of cases. An infection may be documented micro­ biologically (e.g., Pseudomonas aeruginosa bacteremia identified by positive blood cultures) or only clinically (e.g., abdominal pain and bloody diarrhea with negative blood cultures, presumed to represent neutropenic enterocolitis). Using standard diagnostic methods (i.e., routine cultures, serologic tests, and imaging studies) an infection is documented in approximately 40% of episodes of NF. However, newer diagnostic modalities using plasma cell–free DNA polymerase chain reaction (PCR) identify a potential bacterial etiology most of the time. Most bacteria identified by these studies are part of the normal flora of skin and bowel (as are the bacteria isolated by standard culture methods when these are positive), since these physical barriers are often disrupted by the cancer treatments that caused the neutropenia. Infections during neutropenia are typically caused by microorganisms carried by the patient as part of their microbiome. ■ ■MANAGEMENT OF NEUTROPENIC FEVER First Neutropenic Fever  There is a wealth of good-quality evi­ dence to support standard-of-care guidelines for the management of the initial episode of NF. After a swift history and physical exam (focused on potential portals of entry like the vascular catheter exit site, mouth, and perianal area), blood cultures are obtained and empirical antibiotic therapy is initiated using a single agent (monotherapy) with broad-spectrum activity, including coverage of P. aeruginosa. Ideally, anti­ biotics should be given within 1 h of the onset of NF. The diagnostic utility of chest imaging in the absence of respiratory symptoms or signs has not been established. Ceftazidime, cefepime, imipenem, meropenem, and piperacillintazobactam are the best-studied antibiotics used as monotherapy for NF. The specific choice will vary from institution to institution based on the local frequency of resistant bacteria. This “backbone regimen” may be complemented with a second agent against resistant gramnegative or gram-positive bacteria depending on clinical features, prior history of resistant pathogens, or local trends of antimicrobial resistance. It should be emphasized that standard empirical monotherapy regimens for NF apply to clinically stable patients with NF of unclear etiology. Management of neutropenic patients with localized signs of infection (e.g., respiratory, intra-abdominal, intravascular catheter– associated) are discussed below. In patients who are clinically unstable, such as those with hypotension or signs of organ injury raising con­ cern for sepsis (e.g., impaired mental status, pulmonary edema, acute renal injury), a broader-spectrum antimicrobial regimen is warranted. Although the specific regimen for presumed or documented septic shock varies based on the patient’s prior history of resistant infection and local susceptibility patterns, an example of an initial regimen is vancomycin, meropenem, and possibly an aminoglycoside; in patients at risk for candidiasis, an echinocandin may be added. The standard monotherapy regimens lack activity against specific gram-positive pathogens. Gram-positive coverage with a glycopeptide antibiotic (vancomycin in the United States) is not routinely part of the initial regimen. Instead, the addition of a glycopeptide is reserved for clinical situations in which a gram-positive pathogen resistant to the standard regimen (e.g., methicillin-resistant Staphylococcus aureus [MRSA]) is more likely. The Infectious Diseases Society of America (IDSA) guidelines recommend empirical gram-positive coverage with sepsis, clinically evident soft tissue infection, clinically suspected cath­ eter exit site infection, pneumonia, severe mucositis (only if ceftazi­ dime is used as empirical regimen, because mucositis is a risk factor for viridans group streptococci), and known carrier status of MRSA or penicillin-resistant pneumococcus. Meta-analysis has shown that the routine inclusion of vancomycin in the initial regimen is not associated with better outcomes but does result in more nephrotoxicity. After starting antibiotics, fever usually resolves in 24–72 h. If an infection was diagnosed, antibiotics are continued for the appropriate amount of time for that specific infection. When a specific microbe is isolated (e.g., from blood cultures), experts disagree regarding the need for continuing the broad-spectrum coverage versus narrowing based on susceptibility results. If no microorganism is isolated and no source is identified, the optimal strategy for antibiotic management of NF that resolves with antibiotics is debated. In the past, empirical antibiotics were continued until resolution of neutropenia. However, recent studies have suggested that de-escalation from empiric therapy to prophylaxis or discontinua­ tion are safe if specific criteria are met, including clinical stability. The advantage of such de-escalation or early discontinuation strategies relates to reduced antibiotic exposure and lower risk of selection of resistant pathogens; these benefits must be balanced against the poten­ tial for inadequately treated infection. Large, randomized, multicenter trials are required to evaluate the benefits and safety of antibiotic deescalation or discontinuation of empirical antibiotic therapy in patients with persistent neutropenia. Persistent Fever  If the fever continues while receiving empirical antibiotic therapy without a diagnosis, evidence supports and guide­ lines recommend continuing the same antibiotic without addition or modification in the absence of clinical changes or new microbiologic data. The antibacterial regimen should be modified only if new clinical features arise (e.g., hypotension) of if new microbiologic data become available (e.g., a positive culture), and not just because of persistent fever. Although there is agreement on this issue between different guidelines, persistent, stable fever is a common reason why the anti­ bacterial regimen is modified in clinical practice. The longer the neu­ tropenic fever persists during the administration of broad-spectrum antibiotics, the higher the likelihood of IFD. Depending on prior his­ tory, use of antifungal prophylaxis, and local practices, one may choose to initiate empirical antifungal treatment after 5 days of fever (this was standard of care for decades and is called empirical antifungal therapy) or to perform tests focused on diagnosing an occult fungal infec­ tion and initiate antifungals only if these additional tests support the possibility of IFD. This more recent approach has been named preemp­ tive antifungal strategy and seems to result in similar patient outcomes with less use of antifungals. The empirical antifungal of choice will vary depending on the antifungal prophylaxis used (if any). Caspofungin and liposomal amphotericin B are the best-studied empirical antifun­ gal treatment of NF, but expert recommendations vary. A frequently used approach is to administer posaconazole as antifungal prophylaxis in high-risk patients with neutropenia (e.g., those receiving induc­ tion or reinduction regimens for acute myeloid leukemia) and to not modify the antifungal regimen based solely on persistent or recurrent neutropenic fever. Recrudescent Fever and Fever at the Time of Neutrophil Recovery  In addition to the initial episode of fever and persistent fever, there are two other NF scenarios that have been less well stud­ ied: recrudescent fever and fever at the time of neutrophil recovery. Recrudescent fever refers to the situation in which the initial episode of fever resolves without a diagnosis, neutropenia persists, the antibi­ otic regimen is continued unmodified, and fever reappears after the patient has been afebrile for 48–96 h. This is not uncommon during prolonged neutropenia during induction or reinduction therapy in acute leukemia. In this case (as opposed to the first episode of NF), an infection is identified most of the time (bacterial, fungal, or viral), and the recommended approach is to empirically modify the antimicrobial regimen that had successfully controlled the fever up to this point, aiming for coverage of resistant bacteria and fungi. Intensive diagnos­ tic procedures, including CT imaging, should be undertaken. Where available, CT combined with positron emission tomography (CT-PET) may be considered. Finally, fever at the time of neutrophil recovery may be infectious in origin: either a preexisting infection that was silent due to lack of neutrophils (sometimes this is considered analogous to the immune reconstitution inflammatory syndrome [IRIS] seen after initiation of antiretroviral therapy in AIDS) or, less likely, a superinfection. How­ ever, fever is frequently noninfectious at this time and is related to myeloid engraftment. In any case, the recommended response to fever that occurs simultaneously with resolution of neutropenia is not any specific empirical antimicrobial regimen, but to pursue a thorough diagnostic evaluation. ■ ■OUTPATIENT THERAPY FOR NEUTROPENIC FEVER Outpatient therapy for neutropenic fever should be considered in patients at lower risk for infectious complications from neutropenia. These patients typically have solid rather than hematologic tumors with a short expected duration of neutropenia, usually 7 days or less. Criteria for candidates for outpatient empirical therapy include clinical stability, no localizing symptoms or signs of infection, ability to eat and drink without difficulty, absence of significant comorbidities such as chronic lung or cardiovascular disease, normal renal and liver function, and easy access to a hospital and a caregiver at home. Outpatient oral antibiotic therapy in adults typically involves a quinolone (e.g., levo­ floxacin or ciprofloxacin) plus amoxicillin-clavulanate; such regimens are appropriate only for patients who have not received a quinolone as prophylaxis. DOCUMENTED INFECTIONS DURING NEUTROPENIA ■ ■BACTEREMIA Bacteremia is the most common microbiologically documented infec­ tion in neutropenic patients with fever. NF is associated with bacte­ remia in only 10% of cases, but this subgroup of patients has much higher mortality than the general group of neutropenic patients with fever, particularly with gram-negative bacteremia. Most recent series show similar proportions of gram-positive (coagulase-negative Staphylococcus, Streptococcus species, Enterococcus species including vancomycin-resistant Enterococcus [VRE]) and gram-negative bacteria (Enterobacterales and P. aeruginosa). Bacteremia in neutropenic patients may be secondary to another site of infection (e.g., pneumonia, neutropenic enterocolitis, cellulitis) or, most commonly, to mucosal barrier injury (MBI) caused by the anti­ neoplastic treatment. The chemotherapy and/or radiation frequently damages the mucosa of the gastrointestinal tract, facilitating translo­ cation of commensal bacteria during neutropenia. Clinically, one may question whether the bacteremia may be a central line–associated blood­ stream infection (CLABSI). If the isolate is an intestinal bacterium, it is considered related to MBI in the absence of local signs of infection involving the venous catheter. If the isolate is part of the skin flora, like coagulase-negative Staphylococcus, it is more likely to be a CLABSI, but it may also represent a contaminant or colonization of the catheter. Colonization or contamination should be presumed when only one of several blood culture bottles is positive for normal skin flora, especially if the culture takes more than 24 h to turn positive. When a blood culture becomes positive for a gram-positive organism, it is important to repeat blood cultures, ideally from both central and peripheral sites, to determine whether the blood culture isolate is recovered from more than one bottle and at different time points. Skin flora growing from blood drawn from the catheter with negative peripheral blood cultures can reflect catheter colonization (i.e., not a true bloodstream infection) or CLABSI with low levels of bacteria in blood resulting in negative peripheral cultures. When both the peripheral and the central blood cultures are positive for the same organism, bacteremia is con­ firmed, and the differential time to positivity may allow establishing the diagnosis of catheter-related bacteremia if the central line culture grows at least 2 h earlier than the peripheral. However, the practice of always obtaining a peripheral blood culture may not be practical on an oncology ward, where patients may be febrile daily and are frequently thrombocytopenic. CHAPTER 79 Infections in Patients with Cancer More important than whether blood cultures are collected from the central catheter alone or from central and peripheral venous sources is ensuring that an adequate volume of blood (as determined by the specific blood culture platform) is collected. The optimal frequency of blood cultures in NF has not been established. Similarly, the use of surveillance blood cultures in neutropenic patients has not been adequately studied. The amplification by PCR of plasma cell–free DNA, with its superior yield compared with blood cultures, is still investigational, and its place in the routine management of NF remains to be defined. If CLABSI is diagnosed, the preferred treatment is to remove the catheter. Again, this may not always be practical in the case of thrombocytopenic patients with limited access, and an attempt to salvage a permanent catheter (i.e., tunneled catheter or port) may be appropriate as long as the patient remains hemodynamically stable and the blood cultures become negative upon initiating appropriate anti­ biotics. Antibiotic lock therapy should be considered, if feasible. The likelihood of success when a catheter is colonized with S. aureus, mycobacteria, or Candida species is low, and these catheters should be removed as soon as possible. It is customary to provide some time without central access (e.g., a 48-h “line holiday”) before replacing the central venous catheter, although the evidence supporting this practice is scant. Patients may require continuous central IV access, and in this case it is reasonable to use nonsurgically placed lines (e.g., a peripher­ ally inserted central catheter) and to place a new surgically implanted port (e.g., mediport) only when there is clear evidence of blood culture clearance. Endocarditis is rare during neutropenia, but it should be suspected with persistently positive blood cultures or with clinical findings like a new murmur or embolic phenomena. Routine echocardiogram in every case of bacteremia in neutropenic patients is not recommended, but patients with S. aureus bacteremia do require one. ■ ■RESPIRATORY INFECTIONS Sinusitis  Sinusitis may manifest by pressure, facial pain, rhinor­ rhea, and postnasal drip but occasionally has very mild symptoms that will be elicited only by targeted questioning during the physical exam. Symptomatic sinusitis in neutropenic patients may be caused by pathogens relatively uncommon in immunocompetent people, includ­ ing S. aureus, P. aeruginosa, and other gram-negative bacilli. Evaluation by CT and consultation by otolaryngology to examine the integrity of the mucosa and obtain samples for culture is recommended. Invasive fungal sinusitis may be caused by Aspergillus species, agents of mucor­ mycosis, Fusarium species, and relatively less virulent dematiaceous molds like Alternaria, Bipolaris, or Curvularia. CT findings sugges­ tive of fungal etiology include marked asymmetry, heterogeneous radiodensity of the contents of the sinuses, and, later in the disease, bony erosions. The endoscopic exam may show pale, devitalized mucosa and, sometimes, necrotic ulceration of a turbinate caused by the angioinvasive process. Invasive fungal sinusitis during neutropenia mandates surgical resection. Repeated visits to the operating room in conjunction with optimal antifungal therapy are necessary to save the patient’s life. The empirical antifungal agent may vary depending on the preexisting antifungal prophylaxis, but, given the possibility of mucormycosis and fusariosis, many experts would recommend a lipid formulation of amphotericin B, often considered the antifungal of choice for mucormycosis, together with posaconazole, which is nonin­ ferior to voriconazole for Aspergillus species and has superior activity in vitro against dematiaceous molds. Pneumonia  Pulmonary infiltrates are a common diagnostic chal­ lenge in immunocompromised hosts. A systematic approach to the differential, which includes infections and noninfectious etiologies, is mandatory. Some important noninfectious conditions to be consid­ ered include heart failure, fluid overload, transfusion reactions like transfusion-associated circulatory overload (TACO) and transfusionassociated lung injury (TRALI), chemotherapy-associated pneumoni­ tis, organizing pneumonia, and diffuse alveolar hemorrhage, as well as dissemination of the cancer itself. The radiologic appearance is useful to separate unilateral focal processes (suggestive of bacterial or mold infection) from multifocal or diffuse infections, which may be caused in addition by viruses, atypical bacteria, and PJP. Single or multiple dense, well-circumscribed nodules suggest IFD in high-risk patients (e.g., those with leukemia and allogeneic stem cell transplant recipi­ ents), but Nocardia species may have the same appearance and other bacteria like P. aeruginosa and Stenotrophomonas maltophilia may cause angioinvasive infection and result in similar radiology. Unfor­ tunately, characteristic radiologic differences may not hold true in an individual case, and every attempt should be made to obtain a respira­ tory sample for microbiologic diagnosis. PART 4 Oncology and Hematology Early bronchoscopy with bronchoalveolar lavage (BAL) in neutro­ penic patients with pneumonia is recommended. The yield of BAL is highest for diffuse and multifocal processes. In the case of pulmonary nodules accessible to percutaneous or endobronchial biopsy, the choice of diagnostic procedure will often depend on institutional expertise, clinical status, and comorbidities. The empirical antimicrobial regi­ men may vary slightly depending on the radiology and the individual risk factors but should always provide optimal antibacterial coverage by combining one of the antipseudomonal β-lactams together with vancomycin and an agent active against Legionella, like azithromycin, a fluoroquinolone, or doxycycline. If the patient has risk factors for S. maltophilia (high prevalence in the institution, previous exposure to carbapenems), the addition of TMP-SMX or levofloxacin should be considered. The empirical addition of TMP-SMX for PJP depends on the clinical scenario and risk factors. If the only immune defect of the patient is neutropenia, the main concerns are bacteria and molds, the likelihood of PJP is low, and empirical anti-Pneumocystis coverage seems unnec­ essary. However, patients with hematologic malignancies often have received corticosteroids or other agents that decrease cellular immu­ nity and put them at risk for PJP. In this case, empirical coverage until PJP has been ruled out is reasonable. The current gold standard for the diagnosis of PJP is PCR of respiratory secretions, which occasionally may detect patients who are merely colonized. Serum β-d-glucan is typically elevated in patients with PJP, and a positive result increases the likelihood of PJP in a patient with appropriate risk factors and radiologic findings. However, false-positive and -negative β-d-glucan results occur, and this test is not specific for PJP; therefore, a positive serum β-d-glucan does not always obviate the need for BAL. Invasive fungal disease (IFD) is suggested by single or multiple dense, well-circumscribed nodules, particularly larger than 2 cm. The halo sign (ground glass opacity surrounding a dense nodule) or the reverse halo sign (ground glass opacity seen inside a nodule, some­ times said to be more common in mucormycosis) may be present, but these are not diagnostic. Peripheral wedge-shaped infiltrates also may be seen. In patients at high risk for IFD, initiation or escalation of antifungal therapy is commonly begun prior to establishing a diagno­ sis. Such decisions must consider the antifungal prophylaxis that the patient is receiving. If the patient is on fluconazole or no antifungal prophylaxis, a mold-active azole (e.g., voriconazole, posaconazole, isavuconazole) as empirical therapy is reasonable pending a diagnosis, since Aspergillus is by far the most likely mold infection. If on the other hand, a suspected fungal infection occurs while receiving a mold-active azole, many experts would recommend switching the regimen to lipo­ somal amphotericin B, while aggressively pursuing a diagnosis. Evaluation of suspected pneumonia involves sputum and blood cultures, nasopharyngeal swab for PCR for respiratory viruses, urine Legionella antigen, and in patients with neutropenia, evaluation for IFD (e.g., serum galactomannan, beta-glucan) should be included. If these studies are negative and the empirical antimicrobial regimen does not lead to improvement, early BAL or image-guided percutaneous lung biopsy should be considered. If non-invasive diagnostic studies identify a pathogen, it is important to consider the potential for concurrent or secondary infection by other pathogens. For example, respiratory viral infections can be complicated by secondary bacterial pneumonias, and cases of invasive pulmonary aspergillosis following COVID-19 have been documented. It is therefore important to consider a broad differential diagnosis and to repeat imaging and diagnostic evaluation in patients with worsening pneumonia even when an initial diagnosis has been made. ■ ■INTRA-ABDOMINAL INFECTIONS Neutropenic Enterocolitis (Typhlitis)  Sometimes bacteria invade the wall of the intestine and proliferate there, causing inflamma­ tion and even necrosis of segments of the bowel. The clinical syndrome includes fever, abdominal pain, and tenderness and diarrhea, which is occasionally bloody. The term typhlitis (inflammation of the cecum) is sometimes used, as the cecum is most commonly involved, but the terminal ileum, ascending colon, and other segments of the intestine also may be affected, so the more general term neutropenic enterocolitis is preferred. Blood cultures are frequently positive (with bowel flora), but not always. Plain films of the abdomen are not sensitive or specific, but a right lower quadrant soft tissue density, distended bowel loops, ileus, or “thumbprinting” suggesting mucosal edema may sometimes be seen. A CT scan of the abdomen and pelvis usually demonstrates a right lower quadrant inflammatory mass, with thickened bowel wall and stranding of the surrounding fat. Conservative management with broad-spectrum antibiotics, bowel rest, bowel decompression, and nutritional support is usually preferred. Surgery may be required if the patient deteriorates and intestinal perforation, peritonitis, and hemo­ dynamic instability ensue. Carbapenems and piperacillin-tazobactam are appropriate given their broader spectrum. If ceftazidime or cefepime is used, additional agents against anaerobic bacteria (e.g., metronidazole) must be added. In selecting an empirical regimen, it is important to note prior infections with antibiotic-resistant infections, such as VRE, and extended-spectrum β-lactamase (ESBL) of carbapenem-resistant (CRE) gram-negative infections. Similar to intra-abdominal infections, perirectal and perianal infec­ tions are caused by gastrointestinal flora in the context of neutropenia and mucosal injury. CT imaging is helpful to assess the extent of infec­ tion. These infections typically respond to broad-spectrum antibiotic therapy without the need for surgery, but follow-up imaging after neu­ trophil recovery may be necessary if symptoms or fever persist. Clostridioides difficile (C. difficile)–Associated Disease  Cancer patients are at increased risk of C. difficile–associated disease (CDAD) because of their frequent exposure to healthcare facilities, antibiotics, and chemotherapeutic drugs. Patients with a history of CDAD in the previous year are often treated prophylactically with oral vancomycin (125 mg daily) when empirical antibiotic therapy for neutropenic fever is begun. Every hospitalized neutropenic patient with diarrhea should be tested for C. difficile. It is unclear whether neutropenic patients with CDAD have worse outcomes, higher risk of complications, or increased frequency of neutropenic enterocolitis. First-line treatment is fidaxomicin, with oral vancomycin as an alternative. In case of ileus or overwhelming CDAD, combination of either oral fidaxomicin or van­ comycin with IV metronidazole (which is secreted into the intestinal lumen) is recommended. Cholecystitis  Cholecystitis is a rare infection during neutropenia, and most cases have been seen during treatment of acute leukemia. The presentation is like that in nonneutropenic individuals, but bacteremia is more common. At least half of the reported cases have been acal­ culous cholecystitis. Conservative management, frequently including cholecystostomy, is used until resolution of neutropenia when chole­ cystectomy can be performed more safely. ■ ■CENTRAL NERVOUS SYSTEM INFECTIONS Bacterial central nervous system (CNS) infections are uncommon during neutropenia and usually secondary to an episode of bacteremia (which may or may not have been detected) or to extension from the paranasal sinuses. Meningitis caused by gram-negative bacilli, includ­ ing P. aeruginosa, may occur in this setting. Two unexpected causes of CNS infections are worth mentioning. Rothia mucilaginosa, a grampositive coccus that is part of the oral flora, may seed the meninges during a transient bacteremia that seemed to be controlled easily with appropriate antibiotic treatment. This is a rare infection, and most cases treated successfully have received meropenem and vancomycin. Similarly, Bacillus cereus, a gram-positive bacillus ubiquitous in the environment, has been reported as a cause of difficult-to-treat men­ ingitis and brain abscess in neutropenic patients with acute leukemia. The combination of meropenem and vancomycin also has been used successfully. Listeria monocytogenes meningitis and bacteremia are most common in patients with impaired cellular immunity, includ­ ing patients with cancer receiving immunosuppressive regimens. Besides meningitis, L. monocytogenes can also cause rhombencephalitis (inflammation of the brainstem and cerebellum) and brain abscess. The combination of ampicillin and gentamicin is recommended. In cases of penicillin allergy TMP-SMX may be used. Listeria monocyto­ genes is susceptible in vitro to meropenem and linezolid, but clinical experience is limited. In patients with hematologic cancers and prolonged neutropenia, brain lesions should raise the concern for opportunistic pathogens, usually fungi. Aspergillus and Candida brain abscesses are usually hematogenous; mucormycosis more frequently follows extension from the sinuses. Empirical treatment should be administered including antibacterial (typically meropenem plus vancomycin) and antifungal agents until the etiology is established. As mentioned for pulmonary infections, the choice of antifungal may be conditioned by preexisting antifungal prophylaxis. Voriconazole is the preferred agent for CNS aspergillosis and liposomal amphotericin B for mucormycosis. Echino­ candins do not achieve therapeutic levels in the brain or cerebrospinal fluid (CSF), and they should not be relied upon for the treatment of CNS infections. Nocardia species and Toxoplasma gondii are important causes of brain abscess in immunocompromised patients. The major risk factor for these infections is suppressed T cell immunity. In patients with cancer, prolonged intensive corticosteroid therapy and use of purine analogues are examples of risk factors. TMP-SMX used as prophylaxis for PJP may also confer some protection against Listeria, Nocardia, and Toxoplasma. Patients with cancer are at increased risk of viral encephali­ tis. Herpes simplex virus (HSV) encephalitis is characterized by fever and decreased level of consciousness. Imaging shows unilateral involvement of the temporal lobe. Abnormalities in the CSF may be altered by radiation therapy or corticosteroids. The diagnosis is by PCR of the CSF, which may be falsely negative early in the course of the disease. Herpes zoster encephalitis is a rare but devastating complica­ tion in patients with defective T cell immunity. Human herpesvirus 6 (HHV-6) encephalitis is rare outside of allogeneic stem cell transplan­ tation (allo-HCT) (see Chap. 148). Finding a high level of HHV-6 in blood in any other setting brings up the possibility of HHV-6 chromo­ somal integration, which is present in around 1% of the population. In patients who have had neurosurgery, including those with neurosurgical devices (e.g., shunts or reservoirs), infections by grampositive bacteria are most common, although gram-negative infections including coliforms and P. aeruginosa can occur. Risk factors include multiple neurosurgeries (e.g., for recurrent tumor), cranial irradiation, antiangiogenics (which disrupt blood supply), and use of immuno­ suppressives. Vancomycin plus an antipseudomonal cephalosporin (e.g., ceftazidime) is an appropriate initial regimen for postneuro­ surgical CNS infections, pending culture data. Surgical drainage and debridement of infected material and removal of hardware are usually required. CHAPTER 79 ■ ■SKIN AND SOFT TISSUE INFECTIONS As a rule, focal skin lesions in neutropenic, febrile patients should be biopsied, as the diagnostic possibilities are multiple, and some of the causes may be life-threatening and require immediate treatment. Cellulitis may be caused by streptococci or S. aureus, but also by gram-negative bacilli, and broad-spectrum coverage with an antip­ seudomonal β-lactam and vancomycin should be administered until an etiologic diagnosis is established. Multiple foci of erythematous tender plaques with underlying fasciitis and myositis are associated with bacteremia by Clostridium septicum, sometimes seen in patients with colorectal cancer. Ecthyma gangrenosum appears as a tender, erythematous papule that then becomes necrotic and ulcerated. It may be caused by local inoculation or by hematogenous seeding, typically of P. aeruginosa but sometimes other gram-negative bacteria or even molds like Fusarium species. Single or multiple lesions may be seen. Disseminated candidiasis with hematogenous cutaneous disease mani­ fests with fever and other signs of systemic infection and multiple raised cutaneous papules. Hemorrhagic bullae are described in cel­ lulitis caused by gram-negative bacteria (including Vibrio vulnificus, which may be suspected with a history of liver dysfunction and expo­ sure to shellfish). Infections in Patients with Cancer Many noninfectious processes can cause skin lesions, but the pres­ ence of fever is unusual except in Sweet syndrome, also known as acute neutrophilic dermatosis (Fig. 79-2). This is characterized by fever and a variety of skin lesions including papules, nodules, plaques, and some­ times blisters. Skin lesions are often tender and may ulcerate. Sweet syndrome can have many causes, including underlying cancer, usually hematologic. Pathergy is characteristic, and lesions may appear at the insertion site of an intravascular catheter, mimicking infection (Fig. 79-2). Leukemia cutis may manifest as a variety of nontender papules, nodules, or plaques. Fever is unusual. Chemotherapeutic agents can cause a variety of skin reactions, including hyperpigmenta­ tion, hand-foot syndrome (erythema, edema, and blistering of palms and soles), and several rashes. Definitive diagnosis often requires biopsy of skin lesions with appropriate cultures and histopathology. ■ ■URINARY TRACT INFECTIONS It is common to obtain urine cultures in patients with NF regardless of urinary symptoms, and sometimes bacteriuria is detected. The question of whether it is just asymptomatic bacteriuria (common and increasing with age in both men and women), unrelated to the fever, or reflects true urinary tract infection (UTI) necessitating specific treatment may not be immediately answerable. It is appropriate to treat bacteriuria in patients with NF, and standard empirical antibiotic regimens used for NF will cover most urinary pathogens. If UTI is believed to be the source of NF, CT imaging should be considered to A B C D PART 4 Oncology and Hematology FIGURE 79-2  Sweet syndrome. A 47-year-old man admitted for acute myelogenous leukemia (AML) received a surgically implanted catheter and was started on idarubicin and cytosine arabinoside (Ara-C). He developed erythema and tenderness at the insertion site and the cuff site after 24 h, followed by fever. The catheter was removed and cultured (negative) and broad-spectrum antibiotics started, without effect. The catheter exit site worsened, with bullae formation (A). New skin nodules developed on his left thigh, both cheeks, and scalp. Tender induration of the sternocleidomastoid muscle was noticeable clinically and by CT (B). Skin biopsy showed a dense infiltrate of mature neutrophils consistent with Sweet syndrome (C, D). The lesions and the fever resolved promptly with oral prednisone. evaluate for complicated UTI with potential etiologies including geni­ tourinary tract obstruction by tumor or kidney stones, pyelonephritis, and prostatitis. PREVENTION OF INFECTIONS IN PATIENTS WITH CANCER Prevention measures to avoid infections should be tailored to the immune status of the patient and consequent risk of infections. The most stringent measures apply to patients with hematologic malignan­ cies with prolonged neutropenia, to stem cell transplant and adop­ tive cellular therapy recipients, and to other patients who may have prolonged neutropenia for other reasons (e.g., aplastic anemia) or are receiving intensive systemic corticosteroid therapy. At the other end of the spectrum are patients with solid tumors who are in remission and not receiving active chemotherapy or only receiving hormonal agents, such as antiestrogen therapy for breast cancer. These patients should adhere to guidelines to prevent infection that apply to the general population such as hand hygiene, food safety, and guideline-based vac­ cines. This section is focused on prevention measures for patients with cancer at high risk for infections including opportunistic infection. ■ ■ENVIRONMENTAL PRECAUTIONS Inpatient leukemia and transplant wards are typically engineered with HEPA filters and appropriate air exchanges, and individual patient rooms are under positive pressure relative to the outside. The principal rationale for these precautions is to reduce mold spore exposure; these structural precautions were in part driven by outbreaks of aspergillosis. For similar reasons, houseplants are restricted from these wards. Con­ struction, which can release mold spores, must be performed under stringent infection control precautions to minimize patient exposure. In addition to limiting mold exposure, these precautions may have additional benefits to limit airborne transmission of other infections. The vast majority of chemotherapy regimens are administered to outpatients, including to patients with hematologic malignancies receiving intensive immunosuppressive regimens. The stringent envi­ ronmental precautions used for inpatients are not feasible in the out­ patient setting or in the home. Patients should not have construction done in their homes and should avoid exposure to construction sites during periods of significant immune compromise. Patients should also not be involved in gardening, mulching, or similar activities that result in spore exposure. ■ ■PROTECTION FROM FOOD-BORNE INFECTIONS The old practice of implementing “low-microbial diets” for neutrope­ nic patients did not show convincing benefit in well-designed studies and carries the disadvantages of limiting nutrition and affecting quality of life. Patients should be educated about food and water safety precau­ tions issued by the Centers for Disease Control and Prevention (www. cdc.gov/food-safety/foods/weakened-immune-systems.html) and other authoritative bodies that are tailored to immunocompromised persons but are less restrictive than low-microbial diets. These guidelines stress hand hygiene, washing vegetables and fruits, not consuming raw or undercooked meat, poultry, or fish or unpasteurized dairy products, avoidance of waterborne infections, and awareness of food-borne outbreaks. Travel to regions where food and water safety is not reliable should be avoided. Animals also are a potential source of infection, particularly via the fecal–oral route. Patients with cancer should avoid exposure to farm animals and wild animals (e.g., hunting and butchering). Acquiring a new pet while immunocompromised is not advisable. Existing pets can continue to live in the patient’s house, but the patient should avoid direct exposure to animal waste, such as cleaning a cat litter box or bird cage. Patients should avoid dogs recently vaccinated for kennel cough, if possible. Contact with more exotic pets (e.g., reptiles) should be avoided because they can harbor more unusual pathogens (e.g., Salmonella species). ■ ■RESPIRATORY VIRAL INFECTIONS Patients with cancer should avoid contact with persons with symp­ toms or signs of respiratory infection to the extent feasible. Risk of viral infection is increased in congregate settings that are indoors and involve large numbers of people in close proximity. Precautions to limit infection spread, such as choosing outdoor over indoor events and avoiding crowded settings, are advisable. For example, a dinner at a restaurant in which the table is limited to a few persons carries less risk of transmissible infections than a crowded buffet-style setting. Patients with cancer should be aware of local patterns of viral infection. This point was amply demonstrated during the COVID-19 pandemic and applies to other viral infections, such as influenza and respiratory syncytial virus (RSV). If local viral outbreaks occur, patients with cancer should use additional precautions to limit exposure. In addition to avoiding crowds, masking may provide an additional layer of protection, especially in settings of high levels of community spread of respiratory viral infections. ■ ■SEXUAL INTIMACY To avoid risk of sexually transmitted infections, it is recommended that sexual intercourse be in a monogamous relationship. During neutrope­ nia, sexual intercourse and oral–genital or rectal stimulation may cause injury and predispose to infection. Once the ANC recovers, sexual activity usually can be resumed. ■ ■ANTIMICROBIAL PROPHYLAXIS Antimicrobial prophylaxis should be tailored to infection risk. Most patients with solid tumors require no antimicrobial prophylaxis. In addition to side effects of antibiotics, increased risk of C. difficile, and selection of antibiotic-resistant flora, there is precedent for antibiotics diminishing the efficacy of immune checkpoint inhibitors by disrup­ tion of the microbiome. As discussed above, prophylaxis with a quinolone should be con­ sidered in adults with prolonged neutropenia (e.g., ANC <500/µL for at least 7 days). Acyclovir prophylaxis to prevent HSV and VZV # 09 - 80 Oncologic Emergencies ### 80 Oncologic Emergencies reactivation is advised in the majority of patients with hematologic malignancies on active therapy. In patients with AML receiving induc­ tion or reinduction chemotherapy, prophylaxis with posaconazole should be included. Mold-active prophylaxis is also recommended in patients with significant GVHD. PJP prophylaxis is recommended for patients with severe T cell impairment (TMP-SMX is preferred). Exam­ ples include standard induction chemotherapy for acute lymphoblastic leukemia that involves systemic corticosteroids, prolonged corticoste­ roids (described above), use of purine analogues (e.g., cladribine-con­ taining regimens), and GVHD. Pneumococcal prophylaxis (e.g., with penicillin) should be considered for persons with asplenia or chronic GVHD (described above). ■ ■VACCINATION Patients with cancer should receive all recommended non-live vac­ cines based on their approved indications. Yearly recommendations regarding COVID-19 and influenza vaccines should be followed. Patients with solid tumors in general mount greater antibody titers than patients with hematologic malignancies, especially if they have received B cell–depleting agents (e.g., rituximab, BTK inhibitors). However, vaccination is still recommended for such patients with the rationale that they may derive some protective benefit even if subopti­ mal. We also stress vaccination of household members, caretakers, and other close contacts to prevent them from viral infection and transmis­ sion to the patient. Live vaccines should not be given to immunocompromised per­ sons. However, household members including children should receive age-appropriate vaccines, including live vaccines such as MMR and varicella. If the child develops a rash following MMR or varicella vac­ cination, contact with the cancer patient should be limited until the rash resolves. ■ ■FURTHER READING Kamboj M et al: Vaccination of adults with cancer: ASCO guideline. J Clin Oncol 42:1699, 2024. Lehrnbecher T et al: Guideline for the management of fever and neutropenia in pediatric patients with cancer and hematopoietic cell transplantation recipients: 2023 update. J Clin Oncol 41:1774, 2023. Maertens J et al: Empiric vs preemptive antifungal strategy in highrisk neutropenic patients on fluconazole prophylaxis: A randomized trial of the European Organization for Research and Treatment of Cancer. Clin Infect Dis 76:674, 2023. Martinez-Nadal G et al: Inappropriate empirical antibiotic treat­ ment in high-risk neutropenic patients with bacteremia in the era of multidrug resistance. Clin Infect Dis 70:1068, 2020. Maschmeyer G et al: Infectious complications of targeted drugs and biotherapies in acute leukemia. Clinical practice guidelines by the European Conference on Infections in Leukemia (ECIL), a joint ven­ ture of the European Group for Blood and Marrow Transplantation (EBMT), the European Organization for Research and Treatment of Cancer (EORTC), the International Immunocompromised Host Society (ICHS) and the European Leukemia Net (ELN). Leukemia 36: 1215, 2022. Stern A et al: Early discontinuation of antibiotics for febrile neutrope­ nia versus continuation until neutropenia resolution in people with cancer. Cochrane Database Syst Rev 1:CD012184, 2019. Taplitz RA et al: Antimicrobial prophylaxis for adult patients with cancer-related immunosuppression: ASCO and IDSA clinical prac­ tice guideline update. J Clin Oncol 36:3043, 2018. Zimmer AJ et al: Bloodstream infections in hematologic malig­ nancy patients with fever and neutropenia: Are empirical antibiotic therapies in the United States still effective? Open Forum Infect Dis 9:ofac240, 2022. ■ ■WEBSITE NCCN Guidelines. Prevention and Treatment of Cancer-Related Infec­ tions. Version 2.2023. https://www.nccn.org/guidelines/guidelines- detail?category=3&id=1457 Rasim Gucalp, Janice P. Dutcher Oncologic Emergencies Emergencies in patients with cancer may be classified into three groups: pressure or obstruction caused by a space-occupying lesion, metabolic or hormonal problems (paraneoplastic syndromes, Chap. 98), and treatment-related complications. STRUCTURAL-OBSTRUCTIVE ONCOLOGIC EMERGENCIES ■ ■SUPERIOR VENA CAVA SYNDROME Superior vena cava syndrome (SVCS) is the clinical manifestation of superior vena cava (SVC) obstruction, with severe reduction in venous return from the head, neck, and upper extremities. Malignant tumors, such as lung cancer, lymphoma, and metastatic tumors, are responsible for the majority of SVCS cases. With the expanding use of intravascular devices (e.g., permanent central venous access catheters, pacemaker/ defibrillator leads), the prevalence of benign causes of SVCS is now increasing, accounting for at least 40% of cases. Lung cancer, particu­ larly of small-cell and squamous cell histologies, accounts for ~85% of all cases of malignant origin. In young adults, malignant lymphoma is a leading cause of SVCS. Hodgkin’s lymphoma involves the mediastinum more commonly than other lymphomas but rarely causes SVCS. When SVCS is noted in a young man with a mediastinal mass, the differential diagnosis is lymphoma versus primary mediastinal germ cell tumor. Metastatic cancers to the mediastinal lymph nodes, such as testicular and breast carcinomas, account for a small proportion of cases. Other causes include benign tumors, aortic aneurysm, thyromegaly, thrombosis, and fibrosing mediastinitis from prior irradiation, histoplasmosis, or Behçet’s syndrome. SVCS as the initial manifestation of Behçet’s syndrome may be due to inflammation of the SVC associated with thrombosis. CHAPTER 80 Oncologic Emergencies Patients with SVCS usually present with neck and facial swelling (especially around the eyes), dyspnea, and cough. Other symptoms include hoarseness, tongue swelling, headaches, nasal congestion, epi­ staxis, hemoptysis, dysphagia, pain, dizziness, syncope, and lethargy. Bending forward or lying down may aggravate the symptoms. The characteristic physical findings are dilated neck veins; an increased number of collateral veins covering the anterior chest wall; cyanosis; and edema of the face, arms, and chest. Facial swelling and plethora are typically exacerbated when the patient is supine. More severe cases include proptosis, glossal and laryngeal edema, and obtundation. The clinical picture is milder if the obstruction is located above the azygos vein. Symptoms are usually progressive, but in some cases, they may improve as collateral circulation develops. Signs and symptoms of cerebral and/or laryngeal edema, though rare, are associated with a poorer prognosis and require urgent evalu­ ation. Seizures are more likely related to brain metastases than to cere­ bral edema from venous occlusion. Patients with small-cell lung cancer and SVCS have a higher incidence of brain metastases than those without SVCS. Cardiorespiratory symptoms at rest, particularly with positional changes, suggest significant airway and vascular obstruction and limited physiologic reserve. Cardiac arrest or respiratory failure can occur, particularly in patients receiving sedatives or undergoing gen­ eral anesthesia. Rarely, esophageal varices may develop, particularly in the setting of SVC syndrome due to hemodialysis catheter. These are “downhill” varices based on the direction of blood flow from cephalad to caudad (in contrast to “uphill” varices associated with caudad to cephalad flow from portal hypertension). Variceal bleeding may be a late complica­ tion of chronic SVCS. SVC obstruction may lead to bilateral breast edema with bilateral enlarged breasts. Unilateral breast dilation may be seen as a conse­ quence of axillary or subclavian vein blockage. The diagnosis of SVCS is a clinical one. The most significant chest radiographic finding is widening of the superior mediastinum, most commonly on the right side. Pleural effusion occurs in only 25% of patients, often on the right side. The majority of these effusions are exu­ dative and occasionally chylous. However, a normal chest radiograph is still compatible with the diagnosis if other characteristic findings are present. Computed tomography (CT) provides the most reliable view of the mediastinal anatomy. The diagnosis of SVCS requires diminished or absent opacification of central venous structures with prominent collateral venous circulation. The focal hepatic hotspot on CT scan (“hot quadrate”) sign suggests SVC obstruction, and it is caused by portosystemic venous shunting between the SVC and portal vein within liver. Magnetic resonance imaging (MRI) is increasingly being used to diagnose SVC obstruction with a 100% sensitivity and specificity, but dyspneic SVCS patients may have difficulty remaining supine for the entire imaging process. Invasive procedures, includ­ ing bronchoscopy, percutaneous needle biopsy, mediastinoscopy, and even thoracotomy, can be performed by a skilled clinician without any major risk of bleeding. Endobronchial or esophageal ultrasoundguided needle aspiration may establish the diagnosis safely. For patients with a known cancer, a detailed workup usually is not necessary, and appropriate treatment may be started after obtaining a CT scan of the thorax. For those with no history of malignancy, a detailed evaluation is essential to rule out benign causes and determine a specific diagnosis to direct the appropriate therapy. PART 4 Oncology and Hematology TREATMENT Superior Vena Cava Syndrome The one potentially life-threatening complication of a superior mediastinal mass is tracheal obstruction. Upper airway obstruction demands emergent therapy. Diuretics with a low-salt diet, head elevation, and oxygen may produce temporary symptomatic relief. Glucocorticoids have a limited role except in the setting of medias­ tinal lymphoma masses. Radiation therapy is the primary treatment for SVCS caused by non-small-cell lung cancer and other metastatic solid tumors. Che­ motherapy is effective when the underlying cancer is small-cell car­ cinoma of the lung, lymphoma, or germ cell tumor. SVCS recurs in 10–30% of patients; it may be palliated with the use of intravascular self-expanding stents (Fig. 80-1). Endovascular therapy is more fre­ quently used first, to provide rapid relief of clinical symptoms with reduced complications. Early stenting may be necessary in patients with severe symptoms, particularly cerebral or laryngeal edema or postural hypotension; however, the prompt increase in venous return after stenting may precipitate heart failure and pulmonary edema. Other complications of stent placement include hematoma at the insertion site, SVC perforation, stent migration in the right ventricle, stent fracture, and pulmonary embolism. Surgery may play role in treatment of SVCS secondary to nonmalignant medi­ astinal fibrosis. Clinical improvement occurs in most patients, although this improvement may be due to the development of adequate collateral circulation. The mortality associated with SVCS does not relate to caval obstruction but rather to the underlying cause. SVCS AND CENTRAL VENOUS CATHETERS IN ADULTS The use of long-term central venous catheters has become common practice in patients with cancer. Major vessel thrombosis may occur. In these cases, catheter removal should be combined with antico­ agulation to prevent embolization. SVCS in this setting, if detected early, can be treated by fibrinolytic therapy without sacrificing the catheter. When managing patients with transvenous lead-related SVC syndrome, anticoagulation, local and systemic thrombolytic therapy, and surgical intervention can be effective therapy in select patients. Endovascular stenting has also been shown to be safe and promising, with minimal procedural or clinical complications. The role of anticoagulation after SVC stent placement is controversial. A B C FIGURE 80-1  Superior vena cava syndrome (SVCS). A. Chest radiographs of a 59-year-old man with recurrent SVCS caused by non-small-cell lung cancer showing right paratracheal mass with right pleural effusion. B. Computed tomography of same patient demonstrating obstruction of the superior vena cava with thrombosis (arrow) by the lung cancer (square) and collaterals (arrowheads). C. Balloon angioplasty (arrowhead) with Wallstent (arrow) in same patient. ■ ■PERICARDIAL EFFUSION/TAMPONADE Malignant pericardial disease is found at autopsy in 5–10% of patients with cancer, most frequently with lung cancer, breast cancer, leukemias, and lymphomas. Cardiac tamponade as the initial presentation of extrathoracic malignancy is rare. The origin is not malignancy in ~50% of cancer patients with symptomatic pericardial disease, but it can be related to irradiation; drug-induced pericarditis, including chemother­ apeutic agents such as all-trans retinoic acid, arsenic trioxide, imatinib, and other abl kinase inhibitors; hypothyroidism; idiopathic pericarditis; infection; or autoimmune diseases. Pericardial disease has been associ­ ated with immune checkpoint inhibitors specifically in patients with advanced non-small-cell lung cancer. Two types of radiation pericardi­ tis occur: an acute inflammatory, effusive pericarditis occurring within months of irradiation, which usually resolves spontaneously, and a chronic effusive pericarditis that may appear up to 20 years after radia­ tion therapy and is accompanied by a thickened pericardium. Most patients with pericardial metastasis are asymptomatic. How­ ever, the common symptoms are dyspnea, cough, chest pain, orthop­ nea, and weakness. Pleural effusion, sinus tachycardia, jugular venous distention, hepatomegaly, peripheral edema, and cyanosis are the most frequent physical findings. Relatively specific diagnostic findings, such as paradoxical pulse, diminished heart sounds, pulsus alternans (pulse waves alternating between those of greater and lesser amplitude with successive beats), and friction rub are less common than with non­ malignant pericardial disease. Chest radiographs and electrocardio­ gram (ECG) reveal abnormalities in 90% of patients, but half of these abnormalities are nonspecific. Echocardiography is the most helpful diagnostic test. Pericardial fluid may be serous, serosanguineous, or hemorrhagic, and cytologic examination of pericardial fluid is diagnos­ tic in most patients. Measurements of tumor markers in the pericardial fluid are not helpful in the diagnosis of malignant pericardial fluid. Pericardioscopy with targeted pericardial and epicardial biopsy may differentiate neoplastic and benign pericardial disease. A combination of cytology, pericardial and epicardial biopsy, and guided pericardios­ copy gives the best diagnostic yield. CT scan of chest may also reveal the presence of a concomitant thoracic neoplasm. Cancer patients with pericardial effusion containing malignant cells on cytology have a very poor survival. TREATMENT Pericardial Effusion/Tamponade Pericardiocentesis with or without the introduction of sclerosing agents, the creation of a pericardial window, complete pericardial stripping, cardiac irradiation, and systemic chemotherapy are effec­ tive treatments. Acute pericardial tamponade with life-threatening hemodynamic instability requires immediate drainage of fluid. This can be quickly achieved by pericardiocentesis. The recurrence rate after percutaneous catheter drainage is ~20%. Sclerotherapy (peri­ cardial instillation of bleomycin, mitomycin C, or tetracycline) may decrease recurrences. Alternatively, subxiphoid pericardiotomy can be performed in 45 min under local anesthesia. Thoracoscopic pericardial fenestration can be employed for benign causes; how­ ever, 60% of malignant pericardial effusions recur after this proce­ dure. In a subset of patients, drainage of the pericardial effusion is paradoxically followed by worsening hemodynamic instability. This so-called “postoperative low cardiac output syndrome” occurs in up to 10% of patients undergoing surgical drainage and carries poor short-term survival. ■ ■INTESTINAL OBSTRUCTION Intestinal obstruction and reobstruction are common problems in patients with advanced cancer, particularly colorectal or ovarian car­ cinoma. However, other cancers, such as lung or breast cancer and melanoma, can metastasize within the abdomen, leading to intestinal obstruction. Metastatic disease from colorectal, ovarian, pancre­ atic, gastric, and occasionally breast cancer can lead to peritoneal carcinomatosis, with infiltration of the omentum and peritoneal sur­ face, thus limiting bowel motility. Typically, obstruction occurs at mul­ tiple sites in peritoneal carcinomatosis. Melanoma has a predilection to involve the small bowel; this involvement may be isolated, and resection may result in prolonged survival. Intestinal pseudoobstruc­ tion is caused by infiltration of the mesentery or bowel muscle by tumor, involvement of the celiac plexus, or paraneoplastic neuropathy in patients with small-cell lung cancer. Paraneoplastic neuropathy is associated with IgG antibodies reactive to neurons of the myenteric and submucosal plexuses of the jejunum and stomach. Ovarian cancer can lead to authentic luminal obstruction or to pseudoobstruction that results when circumferential invasion of a bowel segment arrests the forward progression of peristaltic contractions. The onset of obstruction is usually insidious. Pain is the most com­ mon symptom and is usually colicky in nature. Pain can also be due to abdominal distention, tumor masses, or hepatomegaly. Vomiting can be intermittent or continuous. Patients with complete obstruction usually have constipation. Physical examination may reveal abdomi­ nal distention with tympany, ascites, visible peristalsis, high-pitched bowel sounds, and tumor masses. Erect plain abdominal films may reveal multiple air-fluid levels and dilation of the small or large bowel. Acute cecal dilation to >12–14 cm is considered a surgical emergency because of the high likelihood of rupture. CT scan is useful in defining the extent of disease and the exact nature of the obstruction and dif­ ferentiating benign from malignant causes of obstruction in patients who have undergone surgery for malignancy. Malignant obstruction is suggested by a mass at the site of obstruction or prior surgery, adenopa­ thy, or an abrupt transition zone and irregular bowel thickening at the obstruction site. Benign obstruction is more likely when CT shows mesenteric vascular changes, a large volume of ascites, or a smooth transition zone and smooth bowel thickening at the obstruction site. In challenging patients with obstructive symptoms, particularly lowgrade small-bowel obstruction (SBO), CT enteroclysis often can help establish the diagnosis by providing distention of small-bowel loops. In this technique, water-soluble contrast is infused through a naso­ enteric tube into the duodenum or proximal small bowel followed by CT images. The prognosis for the patient with cancer who develops intestinal obstruction is poor; median survival is 3–4 months. About 25–30% of patients are found to have intestinal obstruction due to causes other than cancer. Adhesions from previous operations are a common benign cause. Ileus induced by vinca alkaloids, narcotics, or other drugs is another reversible cause. CHAPTER 80 Oncologic Emergencies TREATMENT Intestinal Obstruction The management of intestinal obstruction in patients with advanced malignancy depends on the extent of the underlying malignancy, options for further antineoplastic therapy, estimated life expectancy, the functional status of the major organs, and the extent of the obstruction. The initial management should include surgical evaluation. Operation is not always successful and may lead to further complications with a substantial mortality rate (10–20%). Laparoscopy can diagnose and treat malignant bowel obstruction in some cases. Self-expanding metal stents placed in the gastric outlet, duodenum, proximal jejunum, colon, or rectum may palliate obstructive symptoms at those sites without major sur­ gery. Patients known to have advanced intraabdominal malignancy should receive a prolonged course of conservative management, including nasogastric decompression. Percutaneous endoscopic or surgical gastrostomy tube placement is an option for palliation of nausea and vomiting, the so-called “venting gastrostomy.” Treat­ ment with antiemetics, antispasmodics, and analgesics may allow patients to remain outside the hospital. Octreotide may relieve obstructive symptoms through its inhibitory effect on gastrointes­ tinal secretion. Glucocorticoids have anti-inflammatory effects and may help the resolution of bowel obstruction. ■ ■URINARY OBSTRUCTION Urinary obstruction may occur in patients with prostatic or gyneco­ logic malignancies, particularly cervical carcinoma; metastatic disease from other primary sites such as carcinomas of the breast, stomach, lung, colon, and pancreas; or lymphomas. Radiation therapy to pelvic tumors may cause fibrosis and subsequent ureteral obstruction. Blad­ der outlet obstruction is usually due to prostate and cervical cancers and may lead to bilateral hydronephrosis and renal failure. Flank pain is the most common symptom. Persistent urinary tract infection, persistent proteinuria, or hematuria in patients with cancer should raise suspicion of ureteral obstruction. Total anuria and/or anuria alternating with polyuria may occur. A slow, continuous rise in the serum creatinine level necessitates immediate evaluation. Renal ultrasound is the safest and cheapest way to identify hydronephrosis. The function of an obstructed kidney can be evaluated by a nuclear scan. CT scan can reveal the point of obstruction and identify a retro­ peritoneal mass or adenopathy. TREATMENT Urinary Obstruction Obstruction associated with flank pain, sepsis, or fistula formation is an indication for immediate palliative urinary diversion. Internal ureteral stents can be placed under local anesthesia. Percutane­ ous nephrostomy offers an alternative approach for drainage. The placement of a nephrostomy is associated with a significant rate of pyelonephritis. In the case of bladder outlet obstruction due to malignancy, a suprapubic cystostomy can be used for urinary drainage. An aggressive intervention with invasive approaches to improve the obstruction should be weighed against the likelihood of antitumor response, and the ability to reverse renal insufficiency should be evaluated. PART 4 Oncology and Hematology ■ ■MALIGNANT BILIARY OBSTRUCTION This common clinical problem can be caused by a primary carcinoma arising in the pancreas, ampulla of Vater, bile duct, or liver or by metastatic disease to the periductal lymph nodes or liver parenchyma. The most common metastatic tumors causing biliary obstruction are gastric, colon, breast, and lung cancers. Jaundice, light-colored stools, dark urine, pruritus, and weight loss due to malabsorption are usual symptoms. Pain and secondary infection are uncommon in malig­ nant biliary obstruction. Ultrasound, CT scan, magnetic resonance cholangiopancreatography (MRCP), or percutaneous transhepatic or endoscopic retrograde cholangiopancreatography (ERCP) will identify the site and nature of the biliary obstruction. TREATMENT Malignant Biliary Obstruction Palliative intervention is indicated only in patients with disabling pruritus resistant to medical treatment, severe malabsorption, or infection. Stenting under radiographic control, surgical bypass, or radiation therapy with or without chemotherapy may alleviate the obstruction. The choice of therapy should be based on the site of obstruction (proximal vs distal), the type of tumor (sensitive to radiotherapy, chemotherapy, or neither), and the general condition of the patient. Stenting under radiographic or endoscopic control, surgical bypass, or radiation therapy with or without chemotherapy may alleviate the obstruction. Photodynamic therapy and radiofre­ quency ablation are promising endoscopic therapies for malignant biliary obstruction. Endoscopic ultrasonography-guided biliary drainage is a safe and effective method of biliary drainage in patients with malignant biliary obstruction, particularly in patients whom standard ERCP failed. ■ ■SPINAL CORD COMPRESSION Malignant spinal cord compression (MSCC) is defined as compression of the spinal cord and/or cauda equina by an extradural tumor mass. The minimum radiologic evidence for cord compression is indentation of the theca at the level of clinical features. Spinal cord compression (SCC) occurs in 5–10% of patients with cancer. Epidural tumor is the first manifestation of malignancy in ~10% of patients. The underlying cancer is usually identified during the initial evaluation; lung cancer is the most common cause of MSCC. Metastatic tumor involves the vertebral column more often than any other part of the bony skeleton. Lung, breast, and prostate can­ cers are the most frequent offenders. Multiple myeloma also has a high incidence of spine involvement. Lymphomas, melanoma, renal cell cancer, and genitourinary cancers also cause cord compression. The thoracic spine is the most common site (70%), followed by the lumbosacral spine (20%) and the cervical spine (10%). Involvement of multiple sites is most frequent in patients with breast and prostate car­ cinoma. Cord injury develops when metastases to the vertebral body or pedicle enlarge and compress the underlying dura. Another cause of cord compression is direct extension of a paravertebral lesion through the intervertebral foramen. These cases usually involve a lymphoma, myeloma, or pediatric neoplasm. Parenchymal spinal cord metastasis due to hematogenous spread is rare. Intramedullary metastases can be seen in lung cancer, breast cancer, renal cancer, melanoma, and lymphoma, and are frequently associated with brain metastases and leptomeningeal disease. Expanding extradural tumors induce injury through several mecha­ nisms. Expanding extradural tumors induce mechanical injury to axons and myelin. Compression compromises blood flow, leading to ischemia and/or infarction. The most common initial symptom in patients with SCC is localized back pain and tenderness due to involvement of vertebrae by tumor. Pain is usually present for days or months before other neurologic find­ ings appear. It is exacerbated by movement and by coughing or sneez­ ing. It can be differentiated from the pain of disk disease by the fact that it worsens when the patient is supine. Radicular pain is less common than localized back pain and usually develops later. Radicular pain in the cervical or lumbosacral areas may be unilateral or bilateral. Radicu­ lar pain from the thoracic roots is often bilateral and is described by patients as a feeling of tight, band-like constriction around the thorax and abdomen. Typical cervical radicular pain radiates down the arm; in the lumbar region, the radiation is down the legs. Lhermitte’s sign, a tingling or electric sensation down the back and upper and lower limbs upon flexing or extending the neck, may be an early sign of cord compression. Loss of bowel or bladder control may be the presenting symptom but usually occurs late in the course. Occasionally, patients present with ataxia of gait without motor and sensory involvement due to involvement of the spinocerebellar tract. On physical examination, pain induced by straight leg raising, neck flexion, or vertebral percussion may help to determine the level of cord compression. Patients develop numbness and paresthesias in the extremities or trunk. Loss of sensibility to pinprick is as common as loss of sensibility to vibration or position. The upper limit of the zone of sensory loss is often one or two vertebrae below the site of compression. Motor findings include weakness, spasticity, and abnor­ mal muscle stretching. An extensor plantar reflex reflects significant compression. Deep tendon reflexes may be brisk. Motor and sensory loss usually precedes sphincter disturbance. Patients with autonomic dysfunction may present with decreased anal tonus, decreased perineal sensibility, and a distended bladder. The absence of the anal wink reflex or the bulbocavernosus reflex confirms cord involvement. Autonomic dysfunction is an unfavorable prognostic factor. Patients with progres­ sive neurologic symptoms should have frequent neurologic examina­ tions and rapid therapeutic intervention. Other illnesses that may mimic cord compression include osteoporotic vertebral collapse, disk disease, pyogenic abscess or vertebral tuberculosis, radiation myelopa­ thy, neoplastic leptomeningitis, benign tumors, epidural hematoma, and spinal lipomatosis. Neurologic exam Normal Suspicious for myelopathy Plain spine x-ray Pain crescendo pattern Lhermitte’s sign Pain aggravated with cough, Valsalva, and recumbency Normal Symptomatic therapy Abnormal If symptoms persists or progress FIGURE 80-2  Management of cancer patients with back pain.   Cauda equina syndrome is characterized by low back pain; dimin­ ished sensation over the buttocks, posterior-superior thighs, and perineal area in a saddle distribution; rectal and bladder dysfunc­ tion; sexual impotence; absent bulbocavernous, patellar, and Achil­ les’ reflexes; and variable amount of lower-extremity weakness. This reflects compression of nerve roots as they form the cauda equina after leaving the spinal cord. The majority of cauda equina tumors are primary tumors of glial or nerve sheath origin; metastases are very rare. Patients with cancer who develop back pain should be evaluated for SCC as quickly as possible (Fig. 80-2). Treatment is more often successful in patients who are ambulatory and still have sphincter control at the time treatment is initiated. Patients should have a neuro­ logic examination and plain films of the spine. Those whose physical examination suggests cord compression should receive dexamethasone starting immediately and undergo MRI imaging. Erosion of the pedicles (the “winking owl” sign) is the earliest radiologic finding of vertebral tumor in plain films; however, plain films are insensitive. Other radiographic changes include increased intrapedicular distance, vertebral destruction, lytic or sclerotic lesions, scalloped vertebral bodies, and vertebral body collapse. Vertebral collapse is not a reliable indicator of the presence of tumor; ~20% of cases of vertebral collapse, particularly those in older patients and postmenopausal women, are due not to cancer but to osteoporosis. Also, a normal appearance on plain films of the spine does not exclude the diagnosis of cancer. The role of bone scans in the detection of cord compression is not clear; this method is sensitive but less specific than spinal radiography. The full-length image of the cord provided by MRI is the imaging procedure of choice. Multiple epidural metastases are noted in 25% of Back pain High-dose dexamethasone MRI of spine Epidural metastases No metastases CHAPTER 80 Surgery followed by radiation therapy or radiation therapy alone Symptomatic therapy Oncologic Emergencies Bone metastases but no epidural metastases Symptomatic therapy ± radiation therapy patients with cord compression, and their presence influences treat­ ment plans. On T1-weighted images, good contrast is noted between the cord, cerebrospinal fluid (CSF), and extradural lesions. Owing to its sensitivity in demonstrating the replacement of bone marrow by tumor, MRI can show which parts of a vertebra are involved by tumor. MRI also visualizes intraspinal extradural masses compressing the cord. T2-weighted images are most useful for the demonstration of intra­ medullary pathology. Gadolinium-enhanced MRI can help to delineate intramedullary disease. MRI is as good as or better than myelography plus postmyelogram CT scan in detecting metastatic epidural disease with cord compression. Myelography should be reserved for patients who have poor MRIs or who cannot undergo MRI promptly. CT scan in conjunction with myelography enhances the detection of small areas of spinal destruction. In patients with cord compression and an unknown primary tumor, a simple workup including chest radiography, mammography, measurement of prostate-specific antigen, and abdominal CT usually reveals the underlying malignancy. TREATMENT Spinal Cord Compression The treatment of patients with SCC is aimed at relief of pain and restoration/preservation of neurologic function (Fig. 80-2). Man­ agement of MSCC requires a multidisciplinary approach. Radiation therapy plus glucocorticoids is generally the initial treatment of choice for most patients with SCC. The management decision of SCC involves assessment of neurologic (N), onco­ logic (O), mechanical (M), and systemic factors (S). NOMS was developed by Memorial Sloan Kettering Cancer Center (MSKCC) researchers to provide an algorithm for management of SCC. The neurologic assessment is based on the degree of epidural SCC, myelopathy, and/or functional radiculopathy. Oncologic assess­ ment involves the radiosensitivity of the tumor type. In patients with radioresistant tumors, stereotactic body radiotherapy (SBRT) is the preferred approach if radiation is appropriate. Safe delivery of SBRT requires a 2- to 3-mm margin away from the spinal cord. Separation surgery followed by SBRT is necessary in patients with high-grade SCC due to radioresistant tumors. Separation surgery is the circumferential excision of epidural tumor to reconstitute the thecal sac and provide a 2-mm margin for safe delivery of an abla­ tive radiation dose. In patients with mechanical instability or retro­ pulsion of bone fragments into the spinal canal or cord, a surgical approach is the treatment of choice. Systemic factors that need to be considered are the extent of disease and medical comorbidities that determine the patient’s ability to tolerate planned therapy. Che­ motherapy may have a role in patients with chemosensitive tumors who have had prior radiotherapy to the same region and who are not candidates for surgery. Patients who previously received radio­ therapy for MSCC with an in-field tumor progression can be treated with reirradiation with spine stereotactic radiosurgery (SRS) if they are not surgical candidates. Patients with painful pathologic compression fractures without spinal instability may benefit from percutaneous vertebroplasty or kyphoplasty, the injection of acrylic cement into a collapsed vertebra to stabilize the fracture. Pain palliation is common, and local antitumor effects have been noted. Cement leakage may cause symptoms in ~10% of patients. Bisphosphonates and/or deno­ sumab may be helpful in prevention of SCC in patients with bony involvement. PART 4 Oncology and Hematology The histology of the tumor is an important determinant of both recovery and survival. Rapid onset and progression of signs and symptoms are poor prognostic features. ■ ■INCREASED INTRACRANIAL PRESSURE About 25% of patients with cancer die with intracranial metastases. The cancers that most often metastasize to the brain are lung and breast cancers and melanoma. Brain metastases often occur in the presence of systemic disease, and they frequently cause major symptoms, disability, and early death. The initial presentation of brain metastases from a previously unknown primary cancer is common. Lung cancer is most commonly the primary malignancy. CT scans of the chest/abdomen and MRI of the brain as the initial diagnostic studies can identify a biopsy site in most patients. The signs and symptoms of a metastatic brain tumor are similar to those of other intracranial expanding lesions: headache, nausea, vom­ iting, behavioral changes, seizures, and focal, progressive neurologic changes. Occasionally the onset is abrupt, resembling a stroke, with the sudden appearance of headache, nausea, vomiting, and neurologic deficits. This picture is usually due to hemorrhage into the metastasis. Melanoma, germ cell tumors, and renal cell cancers have a particularly high incidence of intracranial bleeding. The tumor mass and surround­ ing edema may cause obstruction of the circulation of CSF, with result­ ing hydrocephalus. Patients with increased intracranial pressure may have papilledema with visual disturbances and neck stiffness. As the mass enlarges, brain tissue may be displaced through the fixed cranial openings, producing various herniation syndromes. MRI is superior to CT scan. Gadolinium-enhanced MRI is more sensitive than CT at revealing meningeal involvement and small lesions, particularly in the brainstem or cerebellum. The MRI of the brain shows brain metastases as multiple enhancing lesions of various sizes with surrounding areas of low-density edema. Intracranial hypertension (“pseudotumor cerebri”) secondary to tretinoin therapy for acute promyelocytic leukemia has been reported as another cause of intracranial pressure in the setting of a malignancy. TREATMENT Increased Intracranial Pressure Dexamethasone is the best initial treatment for all symptomatic patients with brain metastases. The current success of immuno­ therapy approaches for primary and metastatic brain tumors may preclude or limit glucocorticoid use since it may decrease antitumor response. Bevacizumab should be considered in patients who are unable to wean completely off of steroids as well as those who have symptomatic brain edema and are on immunotherapy. Patients with a single brain metastasis and with controlled extracranial disease may be treated with surgical excision followed by SRS to the resec­ tion cavity. SRS is recommended in patients with a limited number of brain metastases (one to four) who have stable, systemic disease or reasonable systemic treatment options and in patients who have a small number of metastatic lesions in whom whole-brain radia­ tion therapy has failed. The treatment of a larger number of intra­ cranial metastases remains controversial. More patients now receive SRS because of cognitive dysfunction associated with whole-brain radiation. Some patients with increased intracranial pressure asso­ ciated with hydrocephalus may benefit from shunt placement. If neurologic deterioration is not reversed with medical therapy, ventriculotomy to remove CSF or craniotomy to remove tumors or hematomas may be necessary. Targeted agents and checkpoint inhibitors have significant activ­ ity in brain metastases from non-small-cell lung cancer, breast cancer, renal cancer, and melanoma. ■ ■NEOPLASTIC MENINGITIS Tumor involving the leptomeninges is a complication of both primary central nervous system (CNS) tumors and tumors that metastasize to the CNS. The incidence is estimated at 3–8% of patients with cancer. Melanoma, breast and lung cancer, lymphoma (including AIDS-asso­ ciated), and acute leukemia are the most common causes. The lobular or triple-negative subtypes of breast cancer, as well as tumors with expression of the mutant epidermal growth factor receptor (EGFR) or the anaplastic lymphoma kinase (ALK) rearrangement in non-smallcell lung cancer, are more likely to have CNS involvement including neoplastic meningitis and brain metastases. Synchronous intrapa­ renchymal brain metastases are frequent in patients with neoplastic meningitis. Leptomeningeal seeding is frequent in patients undergoing resection of brain metastases or receiving stereotactic radiotherapy for brain metastases. Patients typically present with multifocal neurologic signs and symptoms, including headache, gait abnormality, mental changes, nausea, vomiting, seizures, back or radicular pain, and limb weakness. Signs include cranial nerve palsies, extremity weakness, paresthesia, and decreased deep tendon reflexes. Diagnosis is made by demonstrating malignant cells in the CSF; however, up to 40% of patients may have false-negative CSF cytology. An elevated CSF protein level is nearly always present. Patients with neurologic signs and symptoms consistent with neoplastic meningitis who have a negative CSF cytology should have the spinal tap repeated at least one more time for cytologic examination. MRI findings suggestive of neoplastic meningitis include leptomeningeal, subependymal, dural, or cranial nerve enhancement; superficial cerebral lesions; intradural nodules; and communicating hydrocephalus. Spinal cord imaging by MRI is a necessary component of the evaluation of nonleukemia neo­ plastic meningitis because ~20% of patients have cord abnormalities, including intradural enhancing nodules that are diagnostic for lepto­ meningeal involvement. Cauda equina lesions are common, but lesions may be seen anywhere in the spinal canal. Radiolabeled CSF flow stud­ ies are abnormal in up to 70% of patients with neoplastic meningitis; ventricular outlet obstruction, abnormal flow in the spinal canal, or impaired flow over the cerebral convexities may affect distribution of intrathecal chemotherapy, resulting in decreased efficacy or increased toxicity. Radiation therapy may correct CSF flow abnormalities before use of intrathecal chemotherapy. Neoplastic meningitis can also lead to intracranial hypertension and hydrocephalus. Placement of a ventricu­ loperitoneal shunt may effectively palliate symptoms in these patients. The development of neoplastic meningitis usually occurs in the set­ ting of uncontrolled cancer outside the CNS; thus, prognosis is poor (median survival 10–12 weeks). However, treatment of the neoplastic meningitis may successfully alleviate symptoms and control the CNS spread. TREATMENT Neoplastic Meningitis Chemotherapy provided by either intrathecal injection or systemic routes is used to control leptomeningeal disease throughout the entire neuroaxis. Intrathecal chemotherapy, usually methotrexate, cytarabine, or thiotepa, is delivered by lumbar puncture or by an intraventricular reservoir (Ommaya). Among solid tumors, breast cancer responds best to therapy. Focal radiotherapy may have a role in bulky disease and in symptomatic or obstructive lesions. Targeted therapy such as systemically administered EGFR tyrosine kinase inhibitors (TKIs) in non-small-cell lung cancer may lead to improvement in some patients with leptomeningeal spread. Patients with neoplastic meningitis from either acute leukemia or lym­ phoma may be cured of their CNS disease if the systemic disease can be eliminated. ■ ■SEIZURES Seizures occurring in a patient with cancer can be caused by the tumor itself, by metabolic disturbances, by radiation injury, by cerebral infarctions, by chemotherapy-related encephalopathies, or by CNS infections. Metastatic disease to the CNS is the most common cause of seizures in patients with cancer. However, seizures occur more frequently in primary brain tumors than in metastatic brain lesions. Seizures are a presenting symptom of CNS metastasis in 6–29% of cases. Approximately 10% of patients with CNS metastasis eventually develop seizures. Tumors that affect the frontal, temporal, and parietal lobes are more commonly associated with seizures than are occipital lesions. Both early and late seizures are uncommon in patients with posterior fossa and sellar lesions. Seizures are common in patients with CNS metastases from melanoma and low-grade primary brain tumors. Very rarely, cytotoxic drugs such as etoposide, busulfan, ifosfamide, and chlorambucil cause seizures. Treatment with bispecific antibodies and chimeric antigen receptor (CAR) T cells may also cause CNS tox­ icity including seizures and encephalopathy. Another cause of seizures related to drug therapy is reversible posterior leukoencephalopathy syndrome (RPLS). Chemotherapy, targeted therapy, and immuno­ therapies have been associated with the development of RPLS. RPLS occurs in patients undergoing allogeneic bone marrow or solid-organ transplantation. RPLS is characterized by headache, altered conscious­ ness, generalized seizures, visual disturbances, hypertension, and sym­ metric posterior cerebral white matter vasogenic edema on CT/MRI. Seizures may begin focally but are typically generalized. TREATMENT Seizures Patients in whom seizures due to CNS metastases have been demon­ strated should receive anticonvulsive treatment with levetiracetam, lacosamide, or lamotrigine. Prophylactic anticonvulsant therapy is not recommended. In postcraniotomy patients, prophylactic anti­ epileptic drugs should be withdrawn during the first 2 weeks after surgery. Most antiseizure medications including phenytoin induce cytochrome P450 (CYP450), which alters the metabolism of many antitumor agents, including irinotecan, taxanes, and etoposide, as well as molecular targeted agents, including imatinib, gefitinib, erlotinib, tipifarnib, sorafenib, sunitinib, temsirolimus, everolimus, and vemurafenib. Levetiracetam, lacosamide, and lamotrigine are anticonvulsant agents not metabolized by the hepatic CYP450 system and do not alter the metabolism of antitumor agents. Leve­ tiracetam has become the preferred drug. Surgical resection and other antitumor treatments such as radiotherapy and chemotherapy may improve seizure control. ■ ■PULMONARY AND INTRACEREBRAL LEUKOSTASIS Hyperleukocytosis and the leukostasis syndrome associated with it are potentially fatal complications of acute leukemia (particularly myeloid leukemia) that can occur when the peripheral blast cell count is >100,000/mL. The frequency of hyperleukocytosis is 5–13% in acute myeloid leukemia (AML) and 10–30% in acute lymphoid leukemia; however, leukostasis is rare in lymphoid leukemia. In AML, hyperleu­ kocytosis is more commonly seen in myelomonocytic AML (Fab-M4 and M5), those with 11q13 abnormalities involving the MLL gene, and those with FLT3 mutations. At such high blast cell counts, blood viscosity is increased, blood flow is slowed by aggregates of tumor cells, and the primitive myeloid leukemic cells are capable of invading through the endothelium and causing hemorrhage. Brain and lung are most commonly affected. Patients with brain leukostasis may experi­ ence stupor, headache, dizziness, tinnitus, visual disturbances, ataxia, confusion, coma, or sudden death. On examination, papilledema, retinal vein distension, retinal hemorrhages, and focal deficit may be present. Pulmonary leukostasis may present as respiratory distress and hypoxemia and progress to respiratory failure. Chest radiographs may be normal but usually show interstitial or alveolar infiltrates. Hyperleu­ kocytosis rarely may cause acute leg ischemia, renal vein thrombosis, myocardial ischemia, bowel infraction, and priapism. Arterial blood gas results should be interpreted cautiously. Rapid consumption of plasma oxygen by the markedly increased number of white blood cells can cause spuriously low arterial oxygen tension. Pulse oximetry is the most accurate way of assessing oxygenation in patients with hyperleu­ kocytosis. Hydroxyurea can rapidly reduce a high blast cell count while the diagnostic workup is in progress. After the diagnosis is established, the patient should start quickly with effective induction chemotherapy. Leukapheresis should be used in patients with symptoms of hyper­ leukocytosis. Patients with hyperleukocytosis are also at risk for dis­ seminated intravascular coagulation and tumor lysis syndrome. The clinician should monitor the patient for these complications and take preventive and therapeutic actions during induction therapy. Intra­ vascular volume depletion and unnecessary blood transfusions may increase blood viscosity and worsen the leukostasis syndrome. Leu­ kostasis is very rarely a feature of the high white cell counts associated with chronic lymphoid or chronic myeloid leukemia. CHAPTER 80 Oncologic Emergencies When acute promyelocytic leukemia is treated with differentiating agents like tretinoin and arsenic trioxide, cerebral or pulmonary leu­ kostasis may occur as tumor cells differentiate into mature neutrophils. This complication can be largely avoided by using cytotoxic chemo­ therapy together with the differentiating agents. ■ ■HEMOPTYSIS Hemoptysis may be caused by nonmalignant conditions, but lung can­ cer accounts for a large proportion of cases. Up to 20% of patients with lung cancer have hemoptysis some time in their course. Endobronchial metastases from carcinoid tumors, breast cancer, colon cancer, kidney cancer, and melanoma may also cause hemoptysis. The volume of bleeding is often difficult to gauge. Massive hemoptysis is defined as >200–600 mL of blood produced in 24 h. However, any hemoptysis should be considered massive if it threatens life. When respiratory difficulty occurs, hemoptysis should be treated emergently. The first priorities are to maintain the airway, optimize oxygenation, and stabi­ lize the hemodynamic status. If the bleeding side is known, the patient should be placed in a lateral decubitus position, with the bleeding side down to prevent aspiration into the unaffected lung and given supple­ mental oxygen. If large-volume bleeding continues or the airway is compromised, the patient should be intubated and undergo emergency bronchoscopy. If the site of bleeding is detected, either the patient undergoes a definitive surgical procedure or the lesion is treated with a neodymium:yttrium-aluminum-garnet (Nd:YAG) laser, argon plasma coagulation, or electrocautery. In stable patients, multidetector CT angiography delineates bronchial and nonbronchial systemic arter­ ies and identifies the source of bleeding and underlying pathology with high sensitivity. Massive hemoptysis usually originates from the high-pressure bronchial circulation. Bronchial artery embolization is considered a first-line definitive procedure for managing hemoptysis. Bronchial artery embolization may control brisk bleeding in 75–90% of patients, permitting the definitive surgical procedure to be done more safely if it is appropriate. Embolization without definitive surgery is associated with rebleed­ ing in 20–50% of patients. Recurrent hemoptysis usually responds to a second embolization procedure. A postembolization syndrome charac­ terized by pleuritic pain, fever, dysphagia, and leukocytosis may occur; it lasts 5–7 days and resolves with symptomatic treatment. Bronchial or esophageal wall necrosis, myocardial infarction, and spinal cord infarc­ tion are rare complications. Surgery, as a salvage strategy, is indicated after failure of embolization and is associated with better survival when performed in a nonurgent setting. Pulmonary hemorrhage with or without hemoptysis in hematologic malignancies is often associated with fungal infections, particularly Aspergillus spp. After granulocytopenia resolves, the lung infiltrates in aspergillosis may cavitate and cause massive hemoptysis. Throm­ bocytopenia and coagulation defects should be corrected, if possible. Surgical evaluation is recommended in patients with aspergillosisrelated cavitary lesions. Antibodies to vascular endothelial growth factor (VEGF) including bevacizumab and ramucirumab that inhibit angiogenesis, have been associated with life-threatening hemoptysis in patients with non-small-cell lung cancer, particularly of squamous cell histology. Non-small-cell lung cancer patients with cavitary lesions or previous hemoptysis (≥2.5 mL) within the past 3 months have higher risk for pulmonary hemorrhage. PART 4 Oncology and Hematology ■ ■AIRWAY OBSTRUCTION Airway obstruction refers to a blockage at the level of the mainstem bronchi or above. It may result either from intraluminal tumor growth or from extrinsic compression of the airway. The most common cause of malignant upper airway obstruction is invasion from an adjacent primary tumor, most commonly lung cancer, followed by esophageal, thyroid, and mediastinal malignancies including lymphomas. Extra­ thoracic primary tumors such as renal, colon, or breast cancer can cause airway obstruction through endobronchial and/or mediastinal lymph node metastases. Patients may present with dyspnea, hemoptysis, stridor, wheezing, intractable cough, postobstructive pneumonia, or hoarseness. Chest radiographs usually demonstrate obstructing lesions. CT scans reveal the extent of tumor. Cool, humidified oxygen, glucocor­ ticoids, and ventilation with a mixture of helium and oxygen (Heliox) may provide temporary relief. If the obstruction is proximal to the larynx, a tracheostomy may be lifesaving. For more distal obstructions, particularly intrinsic lesions incompletely obstructing the airway, bron­ choscopy with mechanical debulking and dilation or ablational treat­ ments including laser treatment, photodynamic therapy, argon plasma coagulation, electrocautery, or stenting can produce immediate relief in most patients (Fig. 80-3). However, radiation therapy (either externalbeam irradiation or brachytherapy) given together with glucocorticoids may also open the airway. Symptomatic extrinsic compression may be palliated by stenting. Patients with primary airway tumors such as squamous cell carcinoma, carcinoid tumor, adenocystic carcinoma, or non-small-cell lung cancer, if resectable, should have surgery. METABOLIC EMERGENCIES ■ ■HYPERCALCEMIA Hypercalcemia is the most common paraneoplastic syndrome. Its pathogenesis and management are discussed fully in Chaps. 98 and 422. ■ ■SYNDROME OF INAPPROPRIATE SECRETION OF ANTIDIURETIC HORMONE Hyponatremia is a common electrolyte abnormality in cancer patients, and syndrome of inappropriate secretion of antidiuretic hormone A B FIGURE 80-3  Airway obstruction. A. Computed tomography scan of a 62-year-old man with tracheal obstruction caused by renal carcinoma showing paratracheal mass with tracheal invasion/obstruction (arrow). B. Chest x-ray of same patient after stent (arrows) placement. (SIADH) is the most common cause among patients with cancer. SIADH is discussed fully in Chaps. 98 and 393. ■ ■LACTIC ACIDOSIS Lactic acidosis is a rare and potentially fatal metabolic complication of cancer. Lactic acidosis associated with sepsis and circulatory failure is a common preterminal event in many malignancies. Lactic acidosis in the absence of hypoxemia may occur in patients with leukemia, lym­ phoma, or solid tumors. In some cases, hypoglycemia also is present. Extensive involvement of the liver by tumor is often present. In most cases, decreased metabolism and increased production by the tumor both contribute to lactate accumulation. Tumor cell overexpression of certain glycolytic enzymes and mitochondrial dysfunction can con­ tribute to its increased lactate production. HIV-infected patients have an increased risk of aggressive lymphoma; lactic acidosis that occurs in such patients may be related either to the rapid growth of the tumor or from toxicity of nucleoside reverse transcriptase inhibitors. Symptoms of lactic acidosis include tachypnea, tachycardia, change of mental status, and hepatomegaly. The serum level of lactic acid may reach 10–20 mmol/L (90–180 mg/dL). Treatment is aimed at the underlying disease. Sodium bicarbonate should be added if acidosis is very severe or if hydrogen ion production is very rapid and uncontrolled. Other treatment options include renal replacement therapy, such as hemodi­ alysis, and thiamine replacement. The prognosis is poor regardless of the treatment offered. ■ ■HYPOGLYCEMIA Persistent hypoglycemia is occasionally associated with tumors other than pancreatic islet cell tumors. Usually these tumors are large; tumors of mesenchymal origin, hepatomas, or adrenocortical tumors may cause hypoglycemia. Mesenchymal tumors are usually located in the retroperitoneum or thorax. Obtundation, confusion, and behav­ ioral aberrations occur in the postabsorptive period and may precede the diagnosis of the tumor. These tumors often secrete incompletely processed insulin-like growth factor II (IGF-II), a hormone capable of activating insulin receptors and causing hypoglycemia. Tumors secreting incompletely processed big IGF-II are characterized by an increased IGF-II to IGF-I ratio, suppressed insulin and C-peptide level, and inappropriately low growth hormone and β-hydroxybutyrate concentrations. Rarely, hypoglycemia is due to insulin secretion by a non–islet cell carcinoma. The development of hepatic dysfunction from liver metastases and increased glucose consumption by the tumor can contribute to hypoglycemia. If the tumor cannot be resected, hypo­ glycemia symptoms may be relieved by the administration of glucose, glucocorticoids, recombinant growth hormone, or glucagon. Hypoglycemia can be artifactual; hyperleukocytosis from leukemia, myeloproliferative diseases, leukemoid reactions, or colony-stimulating factor treatment can increase glucose consumption in the test tube after blood is drawn, leading to pseudohypoglycemia. ■ ■ADRENAL INSUFFICIENCY In patients with cancer, adrenal insufficiency may go unrecognized because the symptoms, such as nausea, vomiting, anorexia, and ortho­ static hypotension, are nonspecific and may be mistakenly attributed to progressive cancer or to therapy. Primary adrenal insufficiency may develop owing to replacement of both glands by metastases (lung, breast, colon, or kidney cancer; lymphoma), to removal of both glands, or to hemorrhagic necrosis in association with sepsis or anti­ coagulation. Impaired adrenal steroid synthesis occurs in patients being treated for cancer with mitotane, ketoconazole, or aminoglu­ tethimide or undergoing rapid reduction in glucocorticoid therapy. Megestrol acetate, used to manage cancer and HIV-related cachexia, may suppress plasma levels of cortisol and adrenocorticotropic hor­ mone (ACTH). Patients taking megestrol may develop adrenal insuf­ ficiency, and even those whose adrenal dysfunction is not symptomatic may have inadequate adrenal reserve if they become seriously ill. Paradoxically, some patients may develop Cushing’s syndrome and/or hyperglycemia because of the glucocorticoid-like activity of megestrol acetate. Ipilimumab, an anti-CTLA-4 antibody used for treatment of malignant melanoma and other cancers, may cause autoimmunity including autoimmune-like enterocolitis, hypophysitis (leading to sec­ ondary adrenal insufficiency), hepatitis, and, rarely, primary adrenal insufficiency. Autoimmune hypophysitis may present with headache, visual field defects, and pituitary hormone deficiencies manifesting as hypopituitarism, adrenal insufficiency (including adrenal crisis), or hypothyroidism. Ipilimumab-associated hypophysitis symptoms occur at an average of 6–12 weeks after initiation of therapy. An MRI usually shows homogenous enhancement of pituitary gland. Early glucocor­ ticoid treatment and hormone replacement are the initial treatment. The role of high-dose glucocorticoids in the treatment of hypophysitis is not clear. High-dose glucocorticoids may not improve the frequency of pituitary function recovery. Autoimmune adrenalitis can also be observed with anti-CTLA-4 antibody. Pituitary dysfunction is usually permanent, requiring long-term hormone replacement therapy. Other checkpoint inhibitors, such as monoclonal antibodies targeting pro­ grammed cell death 1 (PD-1), an inhibitory receptor expressed by T cells or one of its ligands (PD-L1), may cause hypophysitis infrequently (~1%). Autoimmune adrenalitis is more frequent with use of PD-1/ PD-L1 than with CTLA-4 inhibitors, but incidence is low. Cranial irradiation for childhood brain tumors may affect the hypothalamuspituitary-adrenal axis, resulting in secondary adrenal insufficiency. Rarely, metastatic replacement causes primary adrenal insufficiency as the first manifestation of an occult malignancy. Metastasis to the pitu­ itary or hypothalamus is found at autopsy in up to 5% of patients with cancer, but associated secondary adrenal insufficiency is rare. Acute adrenal insufficiency is potentially lethal. Treatment of sus­ pected adrenal crisis is initiated after the sampling of serum cortisol and ACTH levels (Chap. 398). TREATMENT-RELATED EMERGENCIES ■ ■TUMOR LYSIS SYNDROME Tumor lysis syndrome (TLS) is characterized by hyperuricemia, hyper­ kalemia, hyperphosphatemia, and hypocalcemia and is caused by the destruction of a large number of rapidly proliferating neoplastic cells. Acidosis may also develop. Acute renal failure occurs frequently. TLS is most often associated with the treatment of Burkitt’s lym­ phoma, acute lymphoblastic leukemia, AML, and other rapidly pro­ liferating lymphomas, but it also may be seen with chronic leukemias and, rarely, with solid tumors. This syndrome is increased in frequency in lymphoid neoplasms treated with venetoclax, a bcl-2 antagonist. TLS has been observed with administration of glucocorticoids, hormonal agents such as letrozole and tamoxifen, and monoclonal antibodies such as rituximab, obinutuzumab, ofatumumab, and gemtuzumab. TLS usually occurs during or shortly (1–5 days) after chemotherapy. Rarely, spontaneous necrosis of malignancies causes TLS. Hyperuricemia may be present at the time of chemotherapy. Effec­ tive treatment kills malignant cells and leads to increased serum uric acid levels from the turnover of nucleic acids. Owing to the acidic local environment, uric acid can precipitate in the tubules, medulla, and col­ lecting ducts of the kidney, leading to renal failure. Lactic acidosis and dehydration may contribute to the precipitation of uric acid in the renal tubules. The finding of uric acid crystals in the urine is strong evidence for uric acid nephropathy. The ratio of urinary uric acid to urinary cre­ atinine is >1 in patients with acute hyperuricemic nephropathy and <1 in patients with renal failure due to other causes. Other events may lead to renal failure in TLS. Calcium phosphate also precipitates in the inter­ stitium and renal microvasculature, leading to nephrocalcinosis. Both types of crystals are toxic to the tubular epithelium, inducing local active inflammatory and pro-oxidative responses. Soluble uric acid may induce hemodynamic changes, with decreased renal blood flow due to vasocon­ striction and impaired autoregulation (crystal-independent pathway). CHAPTER 80 Oncologic Emergencies Hyperphosphatemia, which can be caused by the release of intracel­ lular phosphate pools by tumor lysis, produces a reciprocal depression in serum calcium, which causes severe neuromuscular irritability and tetany. Deposition of calcium phosphate in the kidney and hyperphos­ phatemia may cause renal failure. Potassium is the principal intracellular cation, and massive destruction of malignant cells may lead to hyperka­ lemia. Hyperkalemia in patients with renal failure may rapidly become life threatening by causing ventricular arrhythmias and sudden death. The likelihood that TLS will occur in patients with Burkitt’s lym­ phoma is related to the tumor burden and renal function. Hyperurice­ mia and high serum levels of lactate dehydrogenase (LDH >1500 U/L), both of which correlate with total tumor burden, also correlate with the risk of TLS. In patients at risk for TLS, pretreatment evaluations should include a complete blood count, serum chemistry evaluation, and urinalysis. High leukocyte and platelet counts may artificially elevate potassium levels (“pseudohyperkalemia”) due to lysis of these cells after the blood is drawn. In these cases, plasma potassium instead of serum potassium should be followed. In pseudohyperkalemia, no elec­ trocardiographic abnormalities are present. In patients with abnormal baseline renal function, the kidneys and retroperitoneal area should be evaluated by sonography and/or CT to rule out obstructive uropathy. Urine output should be watched closely. TREATMENT Tumor Lysis Syndrome Recognition of risk and prevention are the most important steps in the management of this syndrome (Fig. 80-4). The standard pre­ ventive approach consists of allopurinol and aggressive hydration. Urinary alkalization with sodium bicarbonate is no longer recom­ mended. It increases uric acid solubility, but a high pH decreases the solubility of xanthine, hypoxanthine, and calcium phosphate, potentially increasing the likelihood of intratubular crystallization. Intravenous allopurinol may be given in patients who cannot toler­ ate oral therapy. Febuxostat, a potent nonpurine selective xanthine Maintain hydration by administration of normal or 1/2 normal saline at 3000 mL/m2 per day Administer allopurinol at 300 mg/m2 per day* Monitor serum chemistry** If, after 24–48 h Serum uric acid >8.0 mg/dL Serum creatinine >1.6 mg/dL Correct treatable renal failure (obstruction) Start recombinant urate oxidase, 0.2 mg/kg IV daily No improvement Delay chemotherapy or start dialysis PART 4 Oncology and Hematology Serum K+ >6.0 meq/L Serum uric acid >10 mg/dL Serum creatinine >10 mg/dL Serum phosphate >10 mg/dL or increasing Symptomatic hypocalcemia present Begin hemodialysis *Use febuxostat in allopurinol allergy and/or renal failure. **Specifically serum electrolytes, creatinine, calcium, phosphate, and uric acid. FIGURE 80-4  Management of patients at high risk for the tumor lysis syndrome.   oxidase inhibitor, is indicated for treatment of hyperuricemia. It results in fewer hypersensitivity reactions than allopurinol. Febuxo­ stat does not require dosage adjustment in patients with mild to moderate renal impairment. Febuxostat achieved significantly superior serum uric acid control in comparison to allopurinol in patients with hematologic malignancies at intermediate to high TLS risk. In some cases, uric acid levels cannot be lowered sufficiently with the standard preventive approach. Rasburicase (recombinant urate oxidase) can be effective in these instances, particularly when renal failure is present. Urate oxidase is missing from pri­ mates and catalyzes the conversion of poorly soluble uric acid to readily soluble allantoin. Rasburicase acts rapidly, decreasing uric acid levels within hours; however, it may cause hypersensitivity reactions such as bronchospasm, hypoxemia, and hypotension. Rasburicase should also be administered to high-risk patients for TLS prophylaxis. Rasburicase is contraindicated in patients with glucose-6-phosphate dehydrogenase deficiency who are unable to break down hydrogen peroxide, an end product of the urate oxidase reaction. Rasburicase is known to cause ex vivo enzymatic degra­ dation of uric acid in test tube at room temperature. This leads to spuriously low uric acid levels during laboratory monitoring of the patient with TLS. Samples must be cooled immediately to deacti­ vate the urate oxidase. Despite aggressive prophylaxis, TLS and/ or oliguric or anuric renal failure may occur. Renal replacement therapy is often necessary and should be considered early in the course. Hemodialysis is preferred. Hemofiltration offers a gradual, continuous method of removing cellular by-products and fluid. Serum uric acid <8.0 mg/dL Serum creatinine <1.6 mg/dL Start chemotherapy a monitor serum chemistry every 6–12 h If ■ ■HUMAN ANTIBODY INFUSION REACTIONS The initial infusion of human or humanized antibodies (e.g., rituximab, gemtuzumab, trastuzumab, alemtuzumab, panitumumab, brentuximab vedotin, blinatumomab) is associated with fever, chills, nausea, asthe­ nia, and headache in up to half of treated patients. Bronchospasm and hypotension occur in 1% of patients. Severe manifestations including pulmonary infiltrates, acute respiratory distress syndrome (ARDS), and cardiogenic shock occur rarely. Laboratory manifestations include elevated hepatic aminotransferase levels, thrombocytopenia, and pro­ longation of prothrombin time. The pathogenesis is thought to be activation of immune effector processes (cells and complement) and release of inflammatory cytokines, such as tumor necrosis factor α, interferon γ, interleukin (IL) 6, and IL-10 (cytokine release syndrome [CRS]). Although its origins are not completely understood, CRS is believed to be due to activation of a variety of cell types including neutrophils, monocytes/macrophages, natural killer cells, and T and B lymphocytes. Hemophagocytic lymphohistiocytosis (HLH)/mac­ rophage activation syndrome (MAS) can develop as part of CRS and usually is a manifestation of severe CRS. Severe CRS may require intensive support for ARDS and resistant hypotension. Emerging clinical experience at several institutions has concluded that tocilizumab is an effective treatment for severe or life-threatening CRS. Tocilizumab prevents IL-6 binding to both cellassociated and soluble IL-6 receptors and therefore inhibits both clas­ sical and trans-IL-6 signaling. Other cytokine-directed therapies, such as siltuximab, a chimeric anti-IL-6 monoclonal antibody, and anakinra, an IL-1 receptor antagonist, have been used. Adoptive transfer of CAR-engineered T cells is a promising therapy for cancers. The most common acute toxicity of CAR T cells is CRS. CAR T cell–associated CRS may be associated with cardiac dysfunc­ tion and neurotoxicity. In all cases, MAS could happen with CRS. The management includes supportive care and tocilizumab. ■ ■HEMOLYTIC-UREMIC SYNDROME Malignancy can induce hemolytic-uremic syndrome (HUS) through a wide variety of mechanisms, including systemic microvascular metastases, extensive bone marrow invasion, or secondary necrosis. HUS syndromes have been reported with metastatic gastric and ovar­ ian cancers, leukemias, and lymphomas. HUS and, less commonly, thrombotic thrombocytopenic purpura (TTP) (Chap. 329) may rarely occur after treatment with antineoplastic drugs, including mitomycin, gemcitabine, cisplatin, bleomycin, and proteasome inhibitors, and with VEGF inhibitors. Mitomycin and gemcitabine are the most common offenders. Unlike mitomycin, there is no clear-cut relationship between the cumulative dose of gemcitabine and risk of HUS. It occurs most often in patients with gastric, lung, colorectal, pancreatic, and breast carcinoma. In one series, 35% of patients were without evident cancer at the time this syndrome appeared. Secondary HUS/TTP has also been reported as a rare but sometimes fatal complication of bone mar­ row transplantation. HUS usually has its onset 4–8 weeks after the last dose of chemo­ therapy, but it is not rare to detect it several months later. HUS is characterized by microangiopathic hemolytic anemia, thrombocy­ topenia, and renal failure. Dyspnea, weakness, fatigue, oliguria, and purpura are also common initial symptoms and findings. Systemic hypertension and pulmonary edema frequently occur. Severe hyper­ tension, pulmonary edema, and rapid worsening of hemolysis and renal function may occur after a blood or blood product transfusion. Cardiac findings include atrial arrhythmias, pericardial friction rub, and pericardial effusion. Raynaud’s phenomenon is part of the syn­ drome in patients treated with bleomycin. Laboratory findings include severe to moderate anemia associ­ ated with red blood cell fragmentation and numerous schistocytes on peripheral smear. Reticulocytosis, decreased plasma haptoglobin, and an LDH level document hemolysis. The serum bilirubin level is usually normal or slightly elevated. The Coombs test is negative. The white cell count is usually normal, and thrombocytopenia (<100,000/μL) is almost always present. Most patients have a normal coagulation profile, although some have mild elevations in thrombin time and in levels of fibrin degradation products. The serum creatinine level is elevated at presentation and shows a pattern of subacute worsening within weeks of the initial azotemia. The urinalysis reveals hematuria, proteinuria, and granular or hyaline casts, and circulating immune complexes may be present. The basic pathologic lesion appears to be deposition of fibrin in the walls of capillaries and arterioles, and these deposits are similar to those seen in HUS due to other causes. These microvascular abnor­ malities involve mainly the kidneys and rarely occur in other organs. The pathogenesis of cancer treatment–related HUS is not completely understood, but probably the most important factor is endothelial damage. Primary forms of HUS/TTP are related to a decrease in pro­ cessing of von Willebrand factor by a protease called ADAMTS13. The case-fatality rate is high; most patients die within a few months. Optimal treatment for chemotherapy-induced HUS is debated. Immu­ nocomplex removal through plasmapheresis, plasma exchange, immu­ noadsorption, or exchange transfusion, antiplatelet and anticoagulant therapies, and immunosuppression have all been employed with vary­ ing degrees of success. The outcome with plasma exchange is generally poor, as in many other cases of secondary TTP. Rituximab is successfully used in patients with chemotherapy-induced HUS as well as in ADAMTS13deficient TTP. Eculizumab, a complement inhibitor, is now considered first-line treatment of atypical HUS. Ravulizumab, a humanized monoclonal antibody that blocks terminal complement activation at C5 and is engineered from eculizumab, has an extended half-life and is approved by the U.S. Food and Drug Administration (FDA) for atypical HUS. Vaccination against Neisseria meningitis is mandatory before eculizumab and ravulizumab are administered. ■ ■NEUTROPENIA AND INFECTION These remain the most common serious complications of cancer therapy. They are covered in detail in Chap. 79. ■ ■PULMONARY INFILTRATES Patients with cancer may present with dyspnea associated with diffuse interstitial infiltrates on chest radiographs. Such infiltrates may be due to progression of the underlying malignancy, treatment-related toxicities, infection, and/or unrelated diseases. The cause may be mul­ tifactorial; however, most commonly, they occur as a consequence of treatment. Infiltration of the lung by malignancy has been described in patients with leukemia, lymphoma, and breast and other solid cancers. Pulmonary lymphatics may be involved diffusely by neoplasm (pul­ monary lymphangitic carcinomatosis), resulting in a diffuse increase in interstitial markings on chest radiographs. The patient is often mildly dyspneic at the onset, but pulmonary failure develops over a period of weeks. In some patients, dyspnea precedes changes on the chest radiographs and is accompanied by a nonproductive cough. This syndrome is characteristic of solid tumors. In patients with leukemia, diffuse microscopic neoplastic peribronchial and peribronchiolar infil­ tration is frequent but may be asymptomatic. However, some patients present with diffuse interstitial infiltrates, an alveolar capillary block syndrome, and respiratory distress. Thickening of bronchovascular bundles and prominence of peripheral arteries are CT findings sug­ gestive of leukemic infiltration. In these situations, glucocorticoids can provide symptomatic relief, but specific chemotherapy should always be started promptly. CHAPTER 80 Oncologic Emergencies Several cytotoxic agents, such as bleomycin, methotrexate, busulfan, nitrosoureas, gemcitabine, mitomycin, vinorelbine, docetaxel, pacli­ taxel, fludarabine, pentostatin, and ifosfamide, may cause pulmonary damage. The most frequent presentations are interstitial pneumonitis, alveolitis, and pulmonary fibrosis. Some cytotoxic agents, including methotrexate and procarbazine, may cause an acute hypersensitivity reaction. Cytosine arabinoside has been associated with noncardio­ genic pulmonary edema. Administration of multiple cytotoxic drugs, as well as radiotherapy and preexisting lung disease, may potentiate the pulmonary toxicity. Supplemental oxygen may potentiate the effects of drugs and radiation injury. Patients should always be managed with the lowest Fio2 that is sufficient to maintain hemoglobin saturation. The onset of symptoms may be insidious, with symptoms including dyspnea, nonproductive cough, and tachycardia. Patients may have bibasilar crepitant rales, end-inspiratory crackles, fever, and cyanosis. The chest radiograph generally shows an interstitial and sometimes an intraalveolar pattern that is strongest at the lung bases and may be sym­ metric. A small effusion may occur. Hypoxemia with decreased carbon monoxide diffusing capacity is always present. Glucocorticoids may be helpful in patients in whom pulmonary toxicity is related to radiation therapy or to chemotherapy. Treatment is otherwise supportive. Molecular targeted agents, imatinib, erlotinib, and gefitinib are potent inhibitors of tyrosine kinases. These drugs may cause interstitial lung disease (ILD). In the case of gefitinib, preexisting fibrosis, poor performance status, and prior thoracic irradiation are independent risk factors; this complication has a high fatality rate. In Japan, inci­ dence of ILD associated with gefitinib was ~4.5% compared to 0.5% in the United States. Osimertinib may cause transient pulmonary opacities (TPOs). TPOs are characterized asymptomatic and localized ground-glass opacities (GGO) with or without nodular consolidation on CT. TPOs typically resolve during continued osimertinib therapy. Temsirolimus and everolimus, both esters of rapamycin (sirolimus), are agents that block the effects of mammalian target of rapamycin (mTOR), an enzyme that has an important role in regulating the synthesis of proteins that control cell division. These agents may cause GGO in the lung with or without diffuse interstitial disease and lung parenchymal consolidation. Patients may be asymptomatic with only radiologic findings or may be symptomatic. Symptoms include cough, dyspnea, and/or hypoxemia, and sometimes patients present with systemic symptoms such as fever and fatigue. The incidence of everolimus-induced ILD also appears to be higher in Japanese patients. HER2-targeting ADC trastuzumab-deruxtecan carries a known risk of ILD with fatality. Treatment includes dose reduction or withdrawal and, in some cases, the addition of glucocorticoids. The FDA-approved immune checkpoint inhibitors (ICIs) of the PD-1 and PD-L1 pathway, including nivolumab, pembrolizumab, dur­ valumab, avelumab, atezolizumab, and cemiplimab, enhance antitumor activity by blocking negative regulators of T-cell function. Immunemediated pneumonitis is rare (10%) but may be a life-threatening complication of these drugs. Pneumonitis symptoms include cough, shortness of breath, dyspnea, and fever, and often involve only asymp­ tomatic radiographic changes. Pneumonitis shows ground-glass patchy lesions and/or disseminated nodular infiltrates, predominantly in the lower lobes. Identifying the exact cause of a pneumonitis in a patient treated with ICIs could be challenging during the current COVID-19 outbreak (Fig. 80-5A). Chest CT manifestations of COVID-19 include an imaging pattern of pure GGO, consolidation, nodules, fibrous stripes, and mixed patterns, with the distribution slightly predomi­ nant in the lower lobe and peripheral areas of the lung. Treatment of immune-mediated pneumonitis includes temporary or permanent withdrawal of drug and the addition of high-dose glucocorticoids (Fig. 80-5B). Radiation pneumonitis and/or fibrosis are relatively frequent side effects of thoracic radiation therapy. It may be acute or chronic. Radiation-induced lung toxicity is a function of the irradiated lung volume, dose per fraction, and radiation dose. The larger the irradi­ ated lung field, the higher is the risk for radiation pneumonitis. The use of concurrent chemoradiation, particularly regimens including PART 4 Oncology and Hematology A FIGURE 80-5  A. Computed tomography scan of a 63-year-old female with metastatic adenocarcinoma on nivolumab with immune check point inhibitor pneumonia showing interlobular septal thickening and diffuse ground-glass opacity to nivolumab. B. Computed tomography scan of a 68-year-old female with resected adenocarcinoma of lung and COVID-19 pneumonia showing peripheral and basilar predominant patchy ground-glass and consolidative opacity consistent with multifocal COVID pneumonia. paclitaxel, increases pulmonary toxicity. Radiation pneumonitis usu­ ally develops 2–6 months after completion of radiotherapy. The clinical syndrome, which varies in severity, consists of dyspnea, cough with scanty sputum, low-grade fever, and an initial hazy infiltrate on chest radiographs. The infiltrate and tissue damage usually are con­ fined to the radiation field. The CT scan may show GGOs, consolida­ tion, fibrosis, atelectatic cicatrization, pleural volume loss, or pleural thickening. The patients subsequently may develop a patchy alveolar infiltrate and air bronchograms, which may progress to acute respira­ tory failure that is sometimes fatal. A lung biopsy may be necessary to make the diagnosis. Asymptomatic infiltrates found incidentally after radiation therapy need not be treated. However, prednisone should be administered to patients with fever or other symptoms. The dosage should be tapered slowly after the resolution of radiation pneumonitis, because abrupt withdrawal of glucocorticoids may cause an exacerbation of pneumonia. Delayed radiation fibrosis may occur years after radiation therapy and is signaled by dyspnea on exertion. Often it is mild, but it can progress to chronic respiratory failure. Therapy is supportive. Classic radiation pneumonitis that leads to pulmonary fibrosis is due to radiation-induced production of local cytokines such as plateletderived growth factor β, tumor necrosis factor, interleukins, and trans­ forming growth factor β in the radiation field. SBRT is a radiotherapy treatment method that has been applied to the treatment of stage I lung cancers in medically inoperable patients. SBRT accurately delivers a high dose of irradiation in one or few treatment fractions to an image-defined lung mass. Most of the acute changes after SBRT occur later than 3 months after treatment, and the shape of the SBRT-induced injury conforms more tightly to the tumor. B Pneumonia is a common problem in patients undergoing treatment for cancer (Chap 79). In patients with pulmonary infiltrates who are afebrile, heart failure and multiple pulmonary emboli are in the dif­ ferential diagnosis. ■ ■NEUTROPENIC ENTEROCOLITIS Neutropenic enterocolitis (typhlitis) is the inflammation and necrosis of the cecum and surrounding tissues that may complicate the treatment of acute leukemia. Nevertheless, it may involve any segment of the gas­ trointestinal tract including small intestine, appendix, and colon. This complication has also been seen in patients with other forms of cancer treated with taxanes, 5-fluorouracil, irinotecan, vinorelbine, cisplatin, carboplatin, sacituzumab govitecan, and high-dose chemotherapy (Fig. 80-6). It also has been reported in patients with AIDS, aplastic anemia, cyclic neutropenia, idiosyncratic drug reactions involving antibiotics, and immunosuppressive therapies. The patient develops right lower quadrant abdominal pain, often with rebound tenderness and a tense, distended abdomen, in a setting of fever and neutropenia. Watery diarrhea (often containing sloughed mucosa) and bacteremia are common, and bleeding may occur. Plain abdominal films are generally of little value in the diagnosis; CT scan may show marked bowel wall thickening, particularly in the cecum, with bowel wall edema, mesenteric stranding, and ascites, and may help to differentiate A B FIGURE 80-6  Abdominal computed tomography (CT) scans of a 72-year-old woman with neutropenic enterocolitis secondary to chemotherapy. A. Air in inferior mesenteric vein (arrow) and bowel wall with pneumatosis intestinalis. B. CT scan of upper abdomen demonstrating air in portal vein (arrows). neutropenic colitis from other abdominal disorders such as appendi­ citis, diverticulitis, and Clostridium difficile–associated colitis in this high-risk population. Patients with bowel wall thickness >10 mm on ultrasonogram have higher mortality rates. However, bowel wall thick­ ening is significantly more prominent in patients with C. difficile colitis. Pneumatosis intestinalis is a more specific finding, seen only in those with neutropenic enterocolitis and ischemia. The combined involve­ ment of the small and large bowel suggests a diagnosis of neutropenic enterocolitis. Rapid institution of broad-spectrum antibiotics, bowel rest, and nasogastric suction may reverse the process. Use of myeloid growth factors improved outcome significantly. Surgical intervention is reserved for severe cases of neutropenic enterocolitis with evidence of perforation, peritonitis, gangrenous bowel, or gastrointestinal hemor­ rhage despite correction of any coagulopathy. C. difficile colitis is increasing in incidence. Newer strains of C. diffi­ cile produce ~20 times more of toxins A and B compared to previously studied strains. C. difficile risk is also increased with chemotherapy. Antibiotic coverage for C. difficile should be added if pseudomembra­ nous colitis cannot be excluded. ■ ■HEMORRHAGIC CYSTITIS Hemorrhagic cystitis is characterized by diffuse bladder mucosal bleeding that develops secondary to chemotherapy (mostly cyclophos­ phamide or ifosfamide), radiation therapy, bone marrow transplanta­ tion (BMT), and/or opportunistic infections. Both cyclophosphamide and ifosfamide are metabolized to acrolein, which is a strong chemical irritant that is excreted in the urine. Prolonged contact or high con­ centrations may lead to bladder irritation and hemorrhage. Symptoms include gross hematuria, frequency, dysuria, burning, urgency, inconti­ nence, and nocturia. The best management is prevention. Maintaining a high rate of urine flow minimizes exposure. In addition, 2-mer­ captoethanesulfonate (mesna) detoxifies the metabolites and can be coadministered with the instigating drugs. Mesna usually is given three times on the day of ifosfamide administration in doses that are each 20% of the total ifosfamide dose. If hemorrhagic cystitis develops, the maintenance of a high urine flow may be sufficient supportive care. If conservative management is not effective, irrigation of the bladder with alum or formalin solution may stop the bleeding in most cases. N-Acet­ ylcysteine may also be an effective irrigant. Prostaglandin (carboprost) can inhibit the process. In extreme cases, ligation of the hypogastric arteries, urinary diversion, or cystectomy may be necessary. CHAPTER 80 Oncologic Emergencies In the BMT setting, early-onset hemorrhagic cystitis is related to drugs in the treatment regimen (e.g., cyclophosphamide), and lateonset hemorrhagic cystitis is usually due to the polyoma virus BKV or adenovirus type 11. BKV load in urine alone or in combination with acute graft-versus-host disease correlates with development of hemor­ rhagic cystitis. Viral causes are usually detected by polymerase chain reaction (PCR)–based diagnostic tests. Treatment of viral hemorrhagic cystitis is largely supportive, with reduction in doses of immunosup­ pressive agents, if possible. No antiviral therapy is approved, although cidofovir was reported to be effective in a small series. Hyperbaric oxy­ gen therapy has been used successfully in patients with BKV-associated and cyclophosphamide-induced hemorrhagic cystitis during hemato­ poietic stem cell transplantation, as well as in hemorrhagic radiation cystitis that occurs in up to 5% of patients after pelvic radiation. ■ ■HYPERSENSITIVITY REACTIONS TO ANTINEOPLASTIC DRUGS Many antineoplastic drugs may cause hypersensitivity reaction. These reactions are unpredictable and potentially life threatening. Most reac­ tions occur during or within hours of parenteral drug administration. Taxanes, platinum compounds, asparaginase, etoposide, procarbazine, and biologic agents, including rituximab, bevacizumab, trastuzumab, gemtuzumab, cetuximab, and alemtuzumab, are more commonly associated with acute hypersensitivity reactions than are other agents. Hypersensitivity reactions to some drugs, such as taxanes, occur dur­ ing the first or second dose administered. Hypersensitivity to platinum compounds occurs after prolonged exposure. Skin testing may identify patients with high risk for hypersensitivity after carboplatin exposure. # 10 - 81 Cancer of the Skin ### 81 Cancer of the Skin Premedication with histamine H1 and H2 receptor antagonists and glucocorticoids reduces the incidence of hypersensitivity reaction to taxanes, particularly paclitaxel. Despite premedication, hypersensitiv­ ity reactions may still occur. In these cases, rapid desensitization in the intensive care unit setting or re-treatment may be attempted with care, but the use of alternative agents may be required. Skin testing is used to assess the involvement of IgE in the reaction. Tryptase levels measured at the time of the reaction help to explain the mechanism of the reac­ tion and its severity. Increased tryptase levels indicate underlying mast cell activation. Candidate patients for desensitization include those who have mild to severe hypersensitivity type I, with mast cell–medi­ ated and IgE-dependent reactions occurring during a chemotherapy infusion or shortly thereafter. ■ ■FURTHER READING Azizi AH et al: Superior vena cava syndrome. JACC Cardiovasc Interv 13:2896, 2020. Castells M et al: Hypersensitivity to antineoplastic agents: Mechanisms and treatment with rapid desensitization. Cancer Immunol Immunother 61:1575, 2012. Castinetti F et al: Endocrine side-effects of new anticancer therapies: Overall monitoring and conclusions. Ann Endocrinol (Paris) 79:591, 2018. Conte P et al: Drug-induced interstitial lung disease during cancer PART 4 Oncology and Hematology therapies: Expert opinion on diagnosis and treatment. ESMO Open 7:1, 2022. Durani U, Hogan WJ: Emergencies in haematology: Tumour lysis syndrome. Br J Haematol 188:494, 2020. Fajgenbaum DC, June CH: Cytokine storm. N Engl J Med 383:2255, 2020. Gonzalez Castro LN, Milligan TA: Seizures in patients with can­ cer. Cancer 126:1379, 2020. Lawton AJ et al: Assessment and management of patients with metastatic spinal cord compression: A multidisciplinary review. J Clin Oncol 37:61, 2019. Paik WH, Park DH: Endoscopic management of malignant biliary obstruction. Gastrointest Endosc Clin N Am 34:127, 2024 Schusler R, Meyerson SL: Pericardial disease associated with malignancy. Curr Cardiol Rep 20:92, 2018. Thomas MR, Scully M: How I treat microangiopathic hemolytic anemia in patients with cancer. Blood 137:1310, 2021. Vogelbaum MA et al: Treatment for brain metastases: ASCO-SNOASTRO Guideline. J Clin Oncol 4:492, 2022. Brendan D. Curti, John T. Vetto, Sancy A. Leachman Cancer of the Skin MELANOMA Pigmented lesions are among the most common findings on skin exam­ ination. The challenge for the physician is to distinguish benign lesions from cutaneous melanomas and nonmelanoma skin cancers (NMSCs), both of which are increasing in frequency. Melanoma accounts for over half of the deaths resulting from skin cancer, although recent advances in immunotherapy and targeted therapy used in the neoadjuvant, adju­ vant, and advanced disease settings have significantly improved sur­ vival. Genomic analysis of melanoma has improved our understanding of prognosis, and informed treatment and surveillance strategies beyond traditional surgical staging. Melanoma is an aggressive malig­ nancy of melanocytes, pigment-producing cells that originate from the neural crest and migrate to the skin, meninges, mucous membranes, upper esophagus, and eyes. Melanocytes in each of these locations have the potential for malignant transformation, but most melanomas arise in the skin, facilitating detection when complete surgical excision can lead to cure. Cutaneous melanoma occurs in people of all ages and all colors. Noncutaneous melanomas have a different biology and a lower probability of response to the immunotherapy agents that have transformed the care of cutaneous melanoma. Examples of malignant melanoma of the skin, mucosa, eye, and nail are shown in Fig. 81-1. ■ ■RISK FACTORS AND EPIDEMIOLOGY The epidemiologic patterns seen in melanoma reflect the genetic and biologic features of melanocytes and their response to environmental ultraviolet radiation (UVR). Clinical features that confer an increased risk for melanoma include: (1) vulnerability to sun damage (light/red coloration of skin, hair, or eyes; photodamaged skin; history of expo­ sure to natural or artificial UVR; prior history of skin cancers of any type); (2) abnormal growth of melanocytes (increased absolute number of nevi, increased size of nevi, or atypical features of moles such as mul­ tiple colors, speckles, or shapes); and (3) immunosuppression (innate, functional, or drug-induced). Table 81-1 summarizes melanoma risk factors and the relative risk associated with these factors. The incidence and mortality rates are strongly influenced by ethnic, geographic, and environmental factors. For instance, the incidence of melanoma is 1/100,000 per year in populations with high skin eumelanin (a brown-black pigment that absorbs ultraviolet [UV] photons efficiently as they enter the epidermis) and up to 27/100,000 per year in populations with low skin eumelanin. Men are affected slightly more than women (1.4:1), and the median age at diagnosis is 66. Melanoma is one several cancer types with increasing incidence in the United States and is now the fifth leading cancer in men (59,170 new cases in 2024; probability 1:28) and the sixth leading cancer in women (41,460 new cases in 2024; probability 1:41). Although these rankings are based on the total number of new invasive melanoma cases in 2024, estimated at 100,640, an addi­ tional 99,700 cases of melanoma in situ (MIS) occurred in 2024. Mortality rates begin to rise at age 55, with the greatest mortality in men age >65 years. In contrast to the increasing incidence, the mortal­ ity rates for melanoma are decreasing, though this trend appears less dramatic outside of the United States. The most likely reason for the decreased mortality is the influence of immunotherapy and targeted therapy on melanoma-specific survival. After U.S. Food and Drug Administration (FDA) approval of ipilimumab and vemurafenib in 2011, the 1-year relative survival rate increased from 42% (2008–2010) to 55% (2013–2015). The mortality rate from 2013 to 2017 dropped annually by 7% in those aged 20–64 years old and dropped 5–6% per year for individuals aged ≥65 years. ■ ■GLOBAL CONSIDERATIONS The incidence of both nonmelanoma and melanoma skin cancers around the world has been increasing. Every year, between 2 and 3 million people develop NMSC, and in 2020, there were 324,635 cases of melanoma. A disproportionate number of cases and deaths occur in North America, Europe, Australia, and New Zealand. The highly variable melanoma incidence rates in different populations are due to the interplay between risk factors, including host genetics and environmental factors, which distribute risk unevenly across these populations and account for the absolute risk in different ethnic groups and geographic areas. Dark-skinned populations (such as those of India and Puerto Rico), blacks, and East Asians also develop melanoma but at rates 10–20 times lower than those in whites. Cutaneous melanomas in dark-skinned populations are more often diagnosed at a higher stage, and patients tend to have worse outcomes. Surveillance, Epidemiology, and End Results (SEER) data (2016–2020) reveal that whites have the highest incidence of melanoma at 37.9 (men) and 25.2 (women) per 100,000 and that the incidence drops substantially in Hispanics (4.5 [men] and 4.3 [women] per 100,000), Native Americans (8.7 [men] and 7.8 [women] per 100,000), Asians/Pacific Islanders (1.3 [men] and 1.1 [women] per 100,000), and blacks (1 [men] and 0.9 [women] per 100,000). In nonwhite (Asian and dark-skinned) populations, the A B C D E F G H I FIGURE 81-1  Types of melanoma. A. Hypomelanotic melanoma. B. Superficial spreading melanoma. C. Melanoma arising in a nevus. D. Seborrheic keratoses-like melanoma arising on the scalp. E. Nodular melanoma. F. Cutaneous melanoma metastases at a surgical margin (also known as melanoma satellites when <2 cm from the primary tumor and in-transit melanoma when >2 cm). G. Mucosal melanoma arising in the vulva. H. Ciliary body melanoma, note visible tumor in the pupil and areas of involvement in the iris and sclera. I. Acral melanoma with Hutchinson’s sign on the proximal nail fold. (Parts A-G and I photos courtesy of Dr. Leonard Swinyer Collection, © Copyright 2020 University of Utah and Oregon Health & Science University. Part H photo courtesy of Dr. Alison Skalet, © Copyright 2022 Oregon Health & Science University [OHSU].) frequency of non–sun-exposed melanomas, such as acral (subungual, plantar, palmar) and mucosal melanomas, is much higher; the inci­ dence of melanoma in black and Hispanic populations is not associated with UV exposure. In China, ~20,000 new melanomas are reported each year, and in contrast to the United States, mortality is increasing. Non–sun-exposed melanomas have a different biology, have a lower probability of response to immunotherapy, and carry a poorer prog­ nosis than cutaneous melanomas, thus accounting for the increase in mortality of this melanoma subgroup. Little is known about the effects of mixed ethnicity on melanoma risk. ■ ■GENETIC SUSCEPTIBILITY TO MELANOMA Approximately 20–40% of hereditary melanomas (0.2–2% of all melanomas) are due to germline mutations in the cell cycle regulatory gene cyclin-dependent kinase inhibitor 2A (CDKN2A). In fact, 70% of all cutaneous melanomas have mutations or deletions affecting the CDKN2A locus on chromosome 9p21. This locus encodes two distinct tumor-suppressor proteins from alternate reading frames: p16 and ARF (p14ARF). The p16 protein inhibits CDK4/6-mediated phosphory­ lation and inactivation of the retinoblastoma (RB) protein, whereas ARF inhibits MDM2 ubiquitin-mediated degradation of p53. The loss of CDKN2A results in inactivation of two critical tumor-suppressor CHAPTER 81 Cancer of the Skin pathways, RB and p53, which control entry of cells into the cell cycle. Several studies have shown an increased risk of pancreatic cancer among melanoma-prone families with CDKN2A mutations. A second high-risk locus for melanoma susceptibility, CDK4, is located on chro­ mosome 12q13 and encodes the cyclin-dependent kinase inhibited by p16. CDK4 mutations, which also inactivate the RB pathway, are much rarer than CDKN2A mutations. Germline mutations in the melanoma lineage-specific oncogene microphthalmia-associated transcription factor (MITF), BRCA1-associated protein 1 (BAP-1), protection of telomeres 1 (POT-1), and telomerase reverse transcriptase (TERT) also predispose to familial melanoma with a not yet quantified high pen­ etrance, based on families that have been tested. The melanocortin-1 receptor (MC1R) gene is a moderate-risk inherited melanoma susceptibility factor. UVR stimulates the produc­ tion of melanocortin (α-melanocyte-stimulating hormone [α-MSH]), the ligand for MC1R, which is a G-protein-coupled receptor that signals via cyclic AMP and regulates the amount and type of pigment produced by melanocytes. MC1R is highly polymorphic, and many among its ~80 variants result in partial or full loss of signaling and lead to the production of non-photoprotective red/yellow pheomelanins, rather than photoprotective brown/black eumelanins. The red hair color (RHC) phenotype produced by MC1R mutations includes lightly TABLE 81-1  Melanoma Risk Factors and Relative Risk RISK LEVEL RISK FACTOR RELATIVE RISK 1 atypical nevus versus 0 1.5 Total common nevi, 16+ versus <15 1.5 Blue eye color versus dark 1.5 Hazel eye color versus dark 1.5 Green eye color versus dark 1.6 Light brown hair versus dark 1.6 Indoor tanning in any gender versus never 1.7 Elevated Fitzpatrick skin type II versus IV 1.8 Fitzpatrick skin type III versus IV 1.8 History of sunburn versus no sunburn 2.0 Blond hair versus dark 2.0 2 atypical nevi versus 0 2.1 Fitzpatrick skin type I versus IV 2.1 High density of freckles versus none 2.1 Total common nevi 41–60 versus <15 2.2 Family history of melanoma in 1 or more first-degree relatives 1.7–3.0 3 atypical nevi versus 0 3.0 Moderately elevated PART 4 Oncology and Hematology Total common nevi 61–80 versus <15 3.3 Red hair versus dark 3.6 Chronic lymphocytic leukemia 3.9 History of actinic keratoses and/or keratinocyte carcinoma versus not 4.3 Indoor tanning in women aged 30–39 versus never 4.3 4 atypical nevi versus 0 4.4 Transplant recipient versus not 2.2–4.6 Indoor tanning in women aged <30 versus never 6.0 5 atypical nevi versus 0 6.4 High Total common nevi 81–120 versus <15 6.9 Personal history of melanoma 8.2–13.4 CDK2NA mutation carrier 14–28 colored skin, red hair, freckles, increased sun sensitivity, and increased risk of melanoma. In addition to its weak UV-shielding capacity rela­ tive to eumelanin, increased pheomelanin production in patients with inactivating polymorphisms of MC1R also provides a UV-independent carcinogenic contribution to melanomagenesis via oxidative damage and reduced DNA damage repair. Other more common, low-penetrance polymorphisms in genes related to pigmentation, nevus count, immune responses, DNA repair, metabolism, and the vitamin D receptor have small effects on melanoma susceptibility. In sum, ~50–60% of the genetic risk for hereditary mela­ noma can be attributed to known melanoma predisposition genes, with ~40% of the known genetic risk attributable to CDKN2A. The other com­ ponents of inherited risk are most likely due to the presence of additional modifier genes and/or shared environmental exposures of the host. ■ ■PREVENTION AND EARLY DETECTION Primary prevention of melanoma and NMSC is based on protection from the sun. Public health initiatives, such as the SunSmart program that started in Australia and is now operative in Europe and the United States, have demonstrated that behavioral change can decrease the incidence of NMSC and melanoma. Preventive measures should start early in life because damage from UV light begins early even though cancers develop years later. Early episodes of sunburns may be a greater risk than chronic tanning. Some individuals tan compulsively. There is now greater understanding of tanning addiction and the cutaneousneural connections that may give rise to this behavior. Compulsive tanners exhibit differences in dopamine binding and reactivity in reward pathways in the brain, such as the basal striatum, resulting in cutaneous secretion of β-endorphins after UV exposure. Identifying individuals with tanning addiction may be another prevention method. Regular use of broad-spectrum sunscreens that block UV-A and UV-B with a sun protection factor (SPF) of at least 30 and protective clothing should be encouraged. Physical blockers such as zinc oxide and tita­ nium dioxide have less likelihood of being absorbed or of generating an allergic reaction than chemical sunscreens. Avoidance of sunburns, tanning beds, and midday sun exposure is recommended. Secondary prevention comprises education and screening with the goal of early detection and can be individualized based on risk factors. A full-body skin exam is warranted in populations at higher risk for melanoma such as patients with clinically atypical moles (dysplastic nevi) and those with a personal history of melanoma. Surveillance in high-risk patients should be performed by a dermatologist and include total-body photography and dermoscopy where appropriate. Individuals with three or more primary melanomas and families with at least one invasive melanoma and two or more cases of melanoma and/or pancreatic cancer, ocular melanoma, mesothelioma, or renal cell carcinoma among first- or second-degree relatives on the same side of the family may benefit from genetic testing. Atypical nevi and MIS should be completely removed with at least a 5-mm margin. Early detection of small lesions allows the use of simpler treatment modali­ ties with higher cure rates and lower morbidity. Monthly self-screening augments provider-based screening. Patients should be taught to recognize the clinical features of melanoma and advised to report any change in a pigmented lesion. There is evidence supporting the ability of media campaigns to reduce cancer mortality in lung cancer, and results from Australia’s skin cancer campaigns demonstrate improve­ ment in attitude and behavior and a reduction in melanoma incidence. A benefit/cost analysis in Australia showed a return of $3.85 for every $1 invested. Although the U.S. Preventive Services Task Force states that there is insufficient evidence to recommend skin screening for the general population, additional research is anticipated to find best practices for skin cancer detection and prevention. ■ ■DIAGNOSIS Early detection of melanoma before it becomes invasive and lifethreatening metastases have occurred is essential and may be facili­ tated by applying the ABCDEs: asymmetry (benign lesions are usually symmetric); border irregularity (most nevi have clear-cut borders); color variegation (benign lesions usually have uniform light or dark pigment); diameter >6 mm (the size of a pencil eraser); and evolving (any change in size, shape, color, or elevation or new symptoms such as bleeding, itching, and crusting). In addition, any nevus that appears atypical and different from the rest of the nevi on that individual (an “ugly duckling”) should be considered suspicious. The entire skin surface, including the scalp and mucous membranes, as well as the nails should be examined in each patient. Bright room illumination is important, and a hand lens or dermatoscope is helpful for evaluating variation in pigment pattern. Any suspicious lesions should be biopsied, evaluated by a specialist, or recorded by chart and/ or photography for follow-up. Dermoscopy employs low-level magni­ fication of the epidermis with polarized light or water interface and permits a more precise visualization of patterns of pigmentation than is possible with the naked eye. Biopsy  Any pigmented cutaneous lesion that has changed on exami­ nation or has the other features previously discussed is a candidate for biopsy. An excisional biopsy with 1- to 3-mm margins (narrow-margin excision) is suggested. This facilitates histologic assessment of the lesion, permits accurate measurement of thickness if the lesion is mela­ noma, and constitutes definitive treatment if the lesion is benign. For lesions that are large or involving anatomic sites where excisional biopsy may not be feasible (such as the face, hands, and feet) or when suspicion of malignancy is low, an incisional biopsy (e.g. shave, saucerization, or punch) to include the most nodular or darkest area of the lesion is acceptable. Incisional biopsy does not appear to facilitate the spread of melanoma. For suspicious lesions, every attempt should be made to preserve the ability to assess the deep and peripheral margins and to perform immunohistochemistry. All biopsies should be deep enough to include the deepest component of the entire lesion, and any pigment at the base of the lesion should be removed and included with the biopsy specimen. Punch biopsies are more likely to clear the deep margin but more likely to be positive at the radial margins; the opposite is true for shave biopsies. The choice of biopsy type should be guided by which is most likely to remove the entire lesion for histologic evaluation. The biopsy should be interpreted by a pathologist experienced in pigmented lesions, and the report should include Breslow thickness, mitotic rate, presence or absence of ulceration, lymphatic/vascular/ neural invasion, regression, microsatellitosis, and the status of the peripheral and deep margins. Breslow thickness is the greatest thickness of a primary cutaneous melanoma measured on the slide from the top of the epidermal granular layer, or from the ulcer base, to the bottom of the tumor. To distinguish melanomas from benign nevi in challenging cases, genetic expression profiles (GEPs), fluorescence in situ hybridiza­ tion with multiple probes, or comparative genomic hybridization can be helpful. GEPs have also been developed to determine prognosis. ■ ■CLASSIFICATION AND PATHOGENESIS Clinical  More recent classifications of melanoma are based on association with cumulative solar damage and nine different pathways related to genomic attributes summarized in Table 81-2. This revised classification incorporates traditional histopathologic designations such as superficial spreading, lentigo maligna, acral lentiginous, and desmoplastic, among others, but more precisely incorporates the pathophysiology and genetic drivers of melanoma subtypes. At present, genomic alteration pathways for melanomas are not incorporated into American Joint Committee on Cancer (AJCC) stag­ ing or prognostic considerations, yet characterizing the genomic and mutational profiles of melanoma has become increasingly common in clinical practice. It is anticipated that genomic pathway characteriza­ tion will become increasingly important in determination of mela­ noma prognosis and may influence surveillance strategies, surgical decisions, and medical therapy. Genomic  The advent of next-generation sequencing has led to whole exome sequencing of thousands of cutaneous melanomas derived from nonglabrous (hair-bearing) skin. This has revealed very complex genomic changes resulting from both germline (see “Genetic Suscepti­ bility to Melanoma” above) and somatic mutations. Cutaneous melano­ mas have one of the highest somatic mutation rates (>10 mutations/Mb) among all cancers; the majority (76% of primary tumors and 84% of TABLE 81-2  Major Histologic Subtypes of Malignant Melanoma TYPE SITE APPEARANCE ASSOCIATED MUTATIONS Lentigo maligna Sun-exposed surfaces, particularly malar region and temple In flat portions, brown and tan predominate, but whitish gray sometimes present; in nodules, reddish brown, bluish gray, bluish black. Superficial spreading Any (more common on upper back and, in women, lower legs) Brown mixed with bluish red, bluish black, reddish brown, and often whitish pink. The lesion border is often visibly and/or palpably raised. Nodular Any Reddish blue, purple, or bluish black; can be uniform or mixed with brown and black. Acral lentiginous Palm, sole, nail bed, mucous membrane In flat portions, dark brown; in raised lesions (plaques), brown-black or blue-black. Desmoplastic Any (more common on head and neck) Highly variable; pigmentation is frequently absent. Can mimic nodular basal cell carcinoma. Uveal Choroid, ciliary body, iris Dome or mushroom shaped. Display low internal reflectivity on ocular ultrasound. Mucosal Oral cavity, conjunctiva, sinuses, alimentary tract including rectum and anus, vulva Can display radial growth pattern with ABCDE features associated with cutaneous melanomas. Often present with advanced tumors infiltrating local tissues Abbreviation: ABCDE, asymmetry (benign lesions are usually symmetric); border irregularity (most nevi have clear-cut borders); color variegation (benign lesions usually have uniform light or dark pigment); diameter >6 mm (the size of a pencil eraser); and evolving (any change in size, shape, color, or elevation or new symptoms such as bleeding, itching, and crusting). metastatic melanomas) exhibit mutations indicative of UVR expo­ sure. The mutation rate varies based on body site; melanomas arising in chronic sun-damaged skin harbor substantially more mutations than melanomas from non–sun-damaged skin. Melanomas can harbor thousands of mutations, but only a few are “driver” mutations that promote cell proliferation or inhibit normal pathways of apoptosis or DNA repair and confer a growth advantage to the neoplastic cell. Some of the driver mutations for cutaneous melanoma are depicted in Fig. 81-2 along with the clinical evolution of melanoma lesions. Driver mutations are often found in combination with mutations to germline susceptibility genes such as p16, which affect cell cycle arrest, and ARF, which result in defective apoptotic responses to genotoxic damage. As melanocytes accumulate DNA damage, they can undergo malignant transformation characterized by invasion, metastasis, and angiogenesis. A genomic classification of cutaneous melanoma has been proposed based on the pattern of the most prevalent mutated genes, BRAF, RAS, and NF1, along with a triple wild type (WT), lacking mutations in these three genes. The pattern of DNA mutations can vary with the site of origin and should be determined along with the histologic subtype of the tumor. The proliferative pathways affected by the mutations include the mitogen-activated protein (MAP) kinase and phosphatidylinositol 3′ kinase/AKT pathways. RAS and BRAF, members of the MAP kinase pathway, which mediates the transcription of genes involved in cell proliferation and survival, undergo somatic mutation in melanoma and thereby represent potential therapeutic targets. NRAS is mutated in ∼20% of melanomas, and somatic activating BRAF mutations are found in most benign nevi and 40–50% of cutaneous melanomas. Neither mutation by itself appears to be sufficient to cause melanoma; thus, they often are accompanied by other mutations, such as in TERT. The BRAF mutation is most commonly a T→A point mutation that results in a valine-to-glutamate amino acid substitution (V600E). V600E BRAF mutations are more common in younger patients and are present in most melanomas that arise on skin with intermittent sun exposure and are less common in melanomas from chronically sun-damaged skin (i.e., those of older patients). CHAPTER 81 Cancer of the Skin Melanomas may harbor mutations in AKT (primarily in AKT3) and PTEN (phosphatase and tensin homolog). AKT can be amplified, and PTEN may be deleted or undergo epigenetic silencing that leads to constitutive activation of the PI3K/AKT pathway and enhanced cell survival by antagonizing the intrinsic pathway of apoptosis. A loss-offunction mutation in NF1, which can affect both the MAP kinase and PI3K/AKT pathways, has been described in 10–15% of melanomas. BRAF 28% NRAS 15% PTEN BRAF 57% NRAS 18% BRAF 47% NRAS 33% NRAS 25% c-KIT 5-10% BRAF 10% MAPK and PI3K 73% High tumor mutational burden, BRAF and NRAS uncommon BAP1, GNAQ, GNA11 KIT, NRAS, KRAS or BRAF NF1 Driver Mutations BRAF: 10% NRAS: 10% C-KIT: 5–10% NF1: 48% of BRAF and NRAS WT melanoma in older patients BRAF: 50% NRAS: 20% C-KIT: 0% Nonchronic Sun Damage Chronic Sun Damage A B C Photodamage De Novo Nevus Dysplastic Nevus F D PART 4 Oncology and Hematology G E FIGURE 81-2  Cutaneous melanoma development and associated driver mutations. Chronic sun damage (with prominent solar elastosis) (A) predisposes to a lentigo maligna (in situ) (B), which can evolve into lentigo maligna melanoma (invasive) (C). Similarly, nonchronic sun damage can initiate melanoma de novo or in nevomelanocytes, where clinical and histologic changes of atypia may be seen prior to complete transformation. Nevi (D, E) can evolve into atypical lesions (F, G), in situ melanoma (H, I), and eventually invasive nodular (J) or superficial spreading melanomas (K). Images E, G, and I are dermascopic photos of images D, F, and H, respectively. (Part A photo courtesy of Dr. Sancy Leachman, © Copyright 2022 Oregon Health & Science University [OHSU]. Parts B, C, J, and K photos courtesy of Dr. Leonard Swinyer Collection, © Copyright 2020 University of Utah and OHSU. Parts D–I photos courtesy of Dr. Elizabeth Berry, © Copyright 2022 OHSU.) In melanoma, these two signaling pathways (MAP kinase and PI3K/ AKT) enhance tumorigenesis, chemoresistance, migration, and cell cycle dysregulation. ■ ■PROGNOSTIC FACTORS The most important clinical prognostic factors for a newly diagnosed patient are incorporated in the AJCC staging classification. The best pre­ dictor of recurrence is Breslow thickness, followed by ulceration, which together make up the T stage for melanoma. The anatomic site of the primary tumor also influences prognosis; favorable sites are the forearm and leg, and unfavorable sites include the scalp, hands, feet, and mucous membranes. Women with stage I or II disease have better survival than men, perhaps in part because of earlier diagnosis; women frequently have melanomas on the lower leg, where self-recognition is more likely compared to the back, where melanoma is more likely in men. Older individuals, especially men >60, have a tendency toward delayed diagnosis (and thus thicker tumors), have more head and neck and acral melanomas (which tend to have earlier vertical growth and distant metastases), and are more likely to develop melanomas in chronically UVR-damaged skin (which are more often BRAF wild type, with fewer options for therapy). All these factors help explain the worse prognosis in older males. Other important adverse factors include high mitotic rate and lymphatic/vascular invasion. Clinical features such as microsatellite lesions and/or in-transit metastases, evidence of nodal involvement, elevated serum lactate dehydrogenase (LDH), and certain sites of distant metastases (e.g., brain, liver, and bone) all portend a higher stage and worse prognosis. GEPs and machine-learning algorithms that associate genomic changes with clinical outcomes have been used to estimate the prog­ nosis of melanoma. A commercially available 31-gene GEP is available that predicts for all-site (particularly distant) relapse and incorporates the increased and decreased expression, as well as the dysregulation, of Lentigo Maligna Lentigo Maligna Melanoma Nodular Melanoma In Situ J H Superficial Spreading K I genes involved in many of the cellular processes leading to melanoma progression described earlier. Although this 31-gene GEP can estimate the probability of distant relapse, it has not supplanted the prognostic estimates derived from surgical staging. GEPs have been incorporated into management guidelines for breast, thyroid, and other cancers, but their use in cutaneous melanoma care is still under investigation. ■ ■STAGING The purpose of staging is to estimate melanoma prognosis and deter­ mine treatment selection. The current melanoma staging criteria and estimated 10-year survival by stage are depicted in Table 81-3. The clinical stage is determined after the microscopic evaluation of the melanoma skin lesion and clinical and radiologic assessment. The pathologic stage incorporates the results from microscopic examina­ tion of clinically negative regional lymph nodes obtained at sentinel lymph node biopsy (SLNB), any enlarged nodes found on exam or imaging, and any suspected metastases amenable to open or imageguided biopsy. All patients should have a complete history, with attention to symp­ toms that suggest metastatic disease, such as new palpable masses, malaise, weight loss, headaches, vision changes, alterations in bowel habits, hemoptysis, and pain. The provider should look for persistent melanoma at the biopsy site, dermal or subcutaneous nodules that could represent satellite or in-transit metastases, and lymphadenopa­ thy. A complete blood count, complete metabolic panel, and LDH should be performed. Although these tests rarely lead to detection of occult metastatic disease, a microcytic anemia would raise the possibil­ ity of bowel metastases, elevated liver function tests can suggest liver metastases, and LDH is part of the AJCC system for stage IV disease. Abnormal test results should prompt a more extensive evaluation, including computed tomography (CT) scan or a positron emission tomography (PET) scan (or CT/PET combined). Magnetic resonance TABLE 81-3  Staging and Survival 10-YEAR MELANOMASPECIFIC SURVIVAL ESTIMATE STAGE TNM TisN0M0 >99% IA T1aN0M0, T1bN0M0 98% IB T2aN0M0 94% IIA T2b-T3aN0M0 88% IIB T3b-T4aN0M0 81–83% IIC T4bN0M0 75% IIIA T1a-T2aN1a-2aM0 71–88% IIIB T2b-T3aN1a-N2bM0 60–77% IIIC T3b-4bN1a-N3cM0 44–60% IIID T4bN3a-N3cM0 24–30% IV M1a Any T, any N, skin, soft tissue, or distant nodal sites 50% at 5 years IV M1b Any T, any N, lung + any M1a sites 35–50% at 5 years IV M1c Any T, any N, skin, non-CNS visceral disease, any M1a or M1b sites ~25% at 5 years IV M1d Any T, any N, CNS metastasis + any M1a,b,c sites <5% at 5 years Abbreviations: CNS, central nervous system; TNM, tumor-node-metastasis. imaging (MRI) of the brain with contrast is recommended for the initial evaluation of patients who present with neurologic symptoms or have advanced disease on imaging or examination. Despite all the above considerations, >80% of patients at presenta­ tion will have disease confined to the skin and a negative history and physical examination, in which case imaging is not indicated. One study suggests that imaging should be considered for node-negative low-stage melanoma with a high-risk GEP, but this is not yet standard. Imaging is sometimes done for very-high-risk primaries (e.g., >4 mm with ulceration, clinical stages IIB and IIC) in which the chance for occult distant metastases is higher than that for a positive SLNB, and the prognosis is worse compared to stage IIIA disease. Medical oncolo­ gists now routinely provide consultation for stage IIB and IIC patients to assess the potential value of adjuvant therapy (see “Treatment”). TREATMENT Melanoma MANAGEMENT OF CLINICALLY LOCALIZED MELANOMA (STAGE I, II) For a newly diagnosed cutaneous melanoma, surgical wide exci­ sion (WE) of the lesion with a margin of normal skin is necessary to remove all malignant cells and minimize the probability of local recurrence. The National Comprehensive Cancer Network (NCCN), based on data from six randomized trials, recommends the following radial margins for a primary MIS, 0.5–1.0 cm; inva­ sive up to 1 mm thick, 1 cm; >1.01–2 mm, 1–2 cm; and >2 mm, 2 cm. Smaller margins may be used for “anatomically constrained” locations such as the face, hands, feet, and genitalia due to the higher likelihood of surgical morbidity in these regions, and in some instances, Mohs with immunostaining is advantageous. In all instances, inclusion of subcutaneous fat in the surgical speci­ men facilitates adequate thickness measurement and assessment of surgical margins by the pathologist. When feasible, excision should go down to fascia, with fascial resection for thick (T4) lesions. Topical imiquimod, a toll-like receptor agonist, can stimulate skin macrophages to induce an immune response useful to treat lentigo maligna in cosmetically sensitive locations with narrow resec­ tion margins by promoting local immune response resulting in decreased local recurrence. SLNB provides prognostic information to identify patients at high risk for relapse who may be candidates for adjuvant therapy. The first (sentinel) draining node(s) from the primary site is (are) located by injecting a blue dye and a gamma-emitting radioisotope around the primary site. The sentinel node(s) then is (are) identified using a handheld gamma detector brought sterilely into the opera­ tive field. The surgeon makes an incision of the area of uptake and looks for the blue-stained, “hot” node(s), which is (are) removed and subjected to histopathologic analysis with serial sectioning using hematoxylin and eosin and immunohistochemical stains (e.g., S100, HMB45, MART-1, and MelanA) to identify melanocytes. NCCN guidelines recommend SLNB for patients with a 10% or greater chance of having tumor in the node. This includes patients with tumors >1 mm thick (T2) or T1 tumors that have ulceration (T1b). Patients with a 5–10% risk of node positivity (NCCN “Dis­ cuss and Consider” category), such as those with tumors measuring between 0.75 and 1.0 mm, transected tumors, regressed tumors, or lymphovascular invasion, should also be considered for SLNB. The NCCN does not recommend SLNB for patients with a risk of a positive SLNB ≤5% such as those with melanomas ≤0.75 mm thick and no high-risk features. In these patients, WE alone is the usual definitive therapy. There are computer nomograms that estimate the risk of sentinel lymph node involvement based on melanoma depth, clinical features (age, site), and histology (ulceration, mitotic rate, lymphovascular invasion). GEPs in combination with these other factors are being investigated as a sentinel lymph node risk assessment tool in ongoing prospective trials. CHAPTER 81 Patients with negative SLNB can either be followed or considered for adjuvant therapy if the primary lesion is considered high risk. Patients with thick and/or ulcerated stage IIB or IIC melanomas have a significant risk of recurrence after wide local excision and (negative) SLNB, estimated at 13–18% probability of death at 5 years using the AJCC melanoma database. Adjuvant anti-PD-1 immunotherapy using pembrolizumab or nivolumab for 1 year sig­ nificantly reduces the risk of melanoma recurrence or death in stage IIB or IIC melanoma and has become a standard of care. Cancer of the Skin Patients with a positive sentinel lymph node should undergo CT or PET/CT imaging to rule out distant metastatic disease, and if none is found (i.e., stage III), adjuvant therapy should be offered (see next section). Complete lymphadenectomy following identifi­ cation of a positive sentinel lymph node improves relapse-free but not overall survival, and therefore, it is no longer offered routinely, but should be considered in patients who cannot comply with follow-up and/or forgo adjuvant therapy. This avoids the morbidity of regional node dissection in most patients. However, patients not undergoing immediate completion node dissection should have nodal bed surveillance with physical examination and nodal bed imaging (ultrasound or CT) at 4- to 6-month intervals for approxi­ mately 3 years to rule out isolated nodal bed progression. Mohs micrographic surgery (MMS) is an alternative to WE and is particularly useful in areas where tissue preservation is important (e.g., face, genitalia, hands) and for lesions with extensive MIS. MMS improves the probability of achieving negative margins, decreases local recurrence, and enhances cosmesis compared to WE in selected patients. It does not preclude SLNB, which can be done before the MMS procedure. MANAGEMENT OF REGIONALLY METASTATIC MELANOMA (STAGE III) Stage III melanoma comprises patients with a positive sentinel lymph node, resected regional nodal macrometastases, or resected locoregional disease (e.g., recurrences in the wide excision site, within 2 cm of the site [“satellite metastases”], or >2 cm from the site [“in-transit metastases”]). Even after complete resection of stage III disease, the risk of developing distant metastases (stage IV) may be high, and adjuvant systemic therapy should be offered. Melanomas may recur at the edge of the incision or graft, as satellite metasta­ ses, in-transit metastases, or most commonly, regional spread to a draining lymph node basin. Each of these presentations is managed surgically followed by postsurgical adjuvant systemic immuno­ therapy or targeted therapy (for BRAF-mutant tumors), after which there is the possibility of long-term disease-free survival. Topical therapy with imiquimod has been useful for patients with lowvolume dermal lesions, but survival benefit has not been confirmed with this approach. Talimogene laherparepvec is an engineered, oncolytic herpes simplex virus type 1 that is FDA approved for injection of primary or recurrent melanomas including cutaneous and subcutaneous lesions or lymph node deposits that cannot be completely removed by surgery. Radiotherapy can reduce the risk of local recurrence after lymph­ adenectomy but does not improve overall survival. Patients with large nodes (>3–4 cm), four or more involved lymph nodes, or extranodal spread on microscopic examination should be consid­ ered for radiation as local recurrence in these high-risk patients has significant morbidity. Systemic adjuvant therapy can also be considered for patients with completely resected stage IV disease. Current options for adjuvant systemic therapy include anti-PD-1 (nivolumab or pembrolizumab) or targeted therapy with BRAF/ MEK inhibitors in melanomas that harbor a BRAF V600 mutation. Both anti-PD-1 and targeted therapy have been shown to confer disease-free and overall survival benefits in patients with stage III and stage IV melanoma (see below for further discussion). A subset of patients with stage III melanoma has bulky disease (usually palpable nodal involvement) at presentation (stages IIIC and IIID) that may be difficult to resect with negative margins. Even if surgery is feasible and postsurgical adjuvant immunotherapy or targeted therapy is offered, the prognosis of these patients is poor. A recent randomized phase II study comparing neoadjuvant therapy followed by resection and adjuvant pembrolizumab versus resection followed by adjuvant pembrolizumab showed significant improvements in event-free and overall survival for the neoadjuvant approach. Other randomized phase II clinical trials investigating neoadjuvant plus adjuvant ipilimumab and nivolumab or relatlimab plus nivolumab in patients with palpable nodal disease at diagnosis have demonstrated a >50% probability of achieving a pathologic complete response with neoadjuvant treatment and a low probability of recurrence at 1 and 2 years. Neoadjuvant plus adjuvant targeted therapy in patients with stage IIIC or IIID BRAF-mutated melanoma has demonstrated a similar high probability of achieving pathologic complete response and improved event-free survival in single-arm phase II studies. Long-term follow-up data from randomized con­ trolled studies of neoadjuvant immunotherapy are not yet mature, and comparisons of immunotherapy to targeted therapy in the neoadjuvant setting have not yet been performed. GEP may help to identify patients with stages II or III melanoma who are at lower risk of recurrence and could avoid the toxicity and expense of adjuvant therapy, although prospective data on this approach are needed. PART 4 Oncology and Hematology TREATMENT Metastatic Disease At diagnosis, 84% of patients with melanoma will have stage I or II disease and 4% will present with metastases. Many others will develop metastases after initial therapy for locoregional disease; 60% of deaths from melanoma occur in patients who were initially diagnosed as stage I or II. The probability of recurrence is related to initial stage, ranging from <5% with stage IA to >90% for subsets of patients with stage IIID disease at presentation. Patients with a history of melanoma who develop signs or symptoms suggesting recurrent disease should undergo restaging imaging as described earlier. Distant metastases (stage IV) commonly involve skin and lymph nodes as well as viscera, bone, or the brain. The prognosis is better for patients with skin and subcutaneous metastases (M1a) than for lung (M1b) and worst for those with metastases to bone or other visceral organs (M1c) or brain (M1d). An elevated serum LDH is a poor prognostic factor and places the patient in stage M1c regardless of the metastatic sites. The 15-year survival of patients with stage IV melanoma was <10% before 2010; however, the development of targeted therapy and immunotherapy has improved TABLE 81-4  Treatment Options for Metastatic Melanoma Immunotherapy   Immune checkpoint blockade     Anti-PD-1: pembrolizumab or nivolumab     Anti-CTLA-4: ipilimumab     Combined ipilimumab and nivolumab     Combined relatlimab (anti-LAG-3) and nivolumab   T-cell engager     Tebentafusp (selected patients with uveal melanoma)   Cytokine-based immunotherapy     High-dose interleukin 2 Clinical trials investigating adoptive cellular therapy with tumor-infiltrating lymphocytes for advanced disease and personalized vaccine targeting neoantigens in high-risk resected melanoma   Oncolytic virus     Talimogene laherparepvec   Targeted therapies     BRAF inhibitors: vemurafenib, dabrafenib, encorafenib     MEK inhibitors: trametinib, cobimetinib, binimetinib   Local modalities     Surgery     Stereotactic radiation disease-free and overall survival, especially for patients with M1a and M1b disease, in whom the 15-year survival is nearly 50%. Even patients with M1c disease may have prolonged survival, and those who are progression-free for >2 years after immunotherapy or targeted therapy have a high probability of living >5 years from the onset of metastasis; some of these individuals may be cured. FDA-approved agents since 2011 include three immune T-cell checkpoint inhibitors (ipilimumab, nivolumab, and pembroli­ zumab), combination immunotherapy (ipilimumab plus nivolumab or relatlimab plus nivolumab), six oral agents that target the MAP kinase pathway (the BRAF inhibitors vemurafenib, dabrafenib, and encorafenib, and the MEK inhibitors trametinib, cobimetinib, and binimetinib), and the oncolytic virus talimogene laherparepvec. Adoptive cellular therapy using tumor-infiltrating lymphocytes (TILs) administered with interleukin 2 is undergoing FDA review and may become a new standard of care for patients with progres­ sion on checkpoint immunotherapy (Table 81-4). Local modalities, such as surgery and stereotactic radiosurgery, should be considered for patients with a limited number of meta­ static sites (oligometastatic disease) because they may experience long-term disease-free survival after metastasectomy or ablative high-dose-per-fraction radiation. Patients with solitary metastases are the best candidates, but local modalities can also be offered to patients with metastases at more than one site if a complete resec­ tion or treatment of all sites can be achieved with reasonable side effects. Patients rendered free of disease can be considered for adjuvant therapy or a clinical trial because their risk of developing additional metastases remains high. Surgery can also be used as an adjunct to systemic therapy if only one or a few oligometastases remain after systemic therapy. Surgery can be used to obtain tumor for mutational profile analysis or to harvest tumor for TIL therapy. IMMUNOTHERAPY Immune Checkpoint Blockade  Immunotherapies are based on an understanding of the control mechanisms of the normal immune response. Inhibitory receptors or checkpoints, including CTLA-4, PD-1, and lymphocyte activation gene 3 (LAG-3), are upregulated on T cells after engagement of the T-cell receptor by cognate tumor antigen in the context of the appropriate class I or II human leu­ kocyte antigen (HLA) molecules during the interaction between a T cell and antigen-presenting cell. Immune checkpoints are needed to ensure proper regulation of a normal immune response; however, the continued expression of inhibitory receptors during chronic infection (hepatitis, HIV) and in cancer patients leads to exhausted T cells with limited potential for proliferation, cytokine production, or cytotoxicity. Ipilimumab, a fully human IgG1 antibody that binds CTLA-4 and blocks inhibitory signals, was the first drug shown in a randomized trial to improve survival in patients with metastatic melanoma. Anti-CTLA-4 monotherapy has been supplanted by anti-PD-1 monotherapy or checkpoint combinations due to higher objective response rates and longer durations of response. The PD-1 blockers, nivolumab and pembrolizumab, have been approved to treat patients with advanced melanoma. Combination T-cell checkpoint therapy, blocking both inhibitory pathways with ipilimumab and nivolumab, leads to superior antitumor activity compared to treatment with either agent alone. Combined therapy with IV ipilimumab and nivolumab is administered in the out­ patient setting every 3 weeks for four doses (induction), followed by nivolumab given every 2–4 weeks (maintenance) for up to 1 year, and is associated with an objective response rate of 56% and enhanced survival compared to ipilimumab monotherapy. Patients who have >5% expression of PD-1 on T cells in a melanoma biopsy sample derive a similar level of clinical benefit from nivolumab mono­ therapy, although using PD-1 expression to select therapy remains problematic as some patients whose melanoma has no detectable PD-1 expression can still respond to immunotherapy. Other elements of genomic analysis, including an estimate of tumor mutational bur­ den (TMB), can be clinically useful as TMB is correlated with a higher probability of objective response and longer progression-free survival in patients treated with checkpoint antibody therapy in melanoma and other solid tumors. TMB appears to be a more robust predictor of response compared to PD-L1 expression in melanoma. LAG-3 is another checkpoint present on CD4+ and CD8+ T cells and is upregulated after chronic antigen exposure. The combination of anti-LAG-3 using relatlimab and anti-PD-1 with nivolumab results in objective responses comparable to ipilimumab plus nivolumab with fewer side effects. Relatlimab plus nivolumab has been approved by the FDA for the first-line treatment of advanced melanoma, has activity after progression on other checkpoint inhibitors, and is being investigated in the neoadjuvant setting as detailed above. T-cell checkpoint antibodies can also interfere with normal immune regulatory mechanisms, producing a novel spectrum of side effects. The most common immune-related adverse events were skin rash (discussed in depth in the Dermatology Drug Eruption section in Chap. 63) and diarrhea (sometimes severe, life-threatening colitis), but toxicity can involve almost any organ resulting in thyroiditis, hypophy­ sitis, hepatitis, nephritis, pneumonitis, myocarditis, and neuritis. The severity and frequency of toxicity are greatest when anti-CTLA-4 and anti-PD-1 are combined, followed by anti-CTLA-4, anti-LAG-3 plus anti-PD-1, and then anti-PD-1 monotherapies. Vigilance, interruption of therapy, and early intervention with steroids or other immuno­ suppressive agents, such as anti–tumor necrosis factor antibodies or mycophenolate mofetil, can mitigate toxicity and prevent permanent organ damage. Using immunosuppressive agents to mitigate toxicity does not diminish antitumor activity, and benefit is manifest even in patients who must discontinue immunotherapy due to immune-medi­ ated toxicity. Checkpoint immunotherapy can be administered safely to selected patients with preexisting autoimmune conditions using a multidisciplinary approach with input from endocrinology, rheuma­ tology, and other specialty services as clinically necessary. The use of T-cell checkpoint antibodies for metastatic melanoma has become commonplace, but there is controversy about whether all patients need combined anti-CTLA-4 and anti-PD-1 and whether biomarkers can be used to select patients who may benefit from anti-PD-1 alone. There is also a significant economic impact with any anticancer therapy, which must be placed in the context of the survival benefit. TARGETED THERAPY The RAS-RAF-MEK-ERK pathway delivers proliferation and sur­ vival signals from the cell surface to the cytoplasm and nucleus and is mutated in approximately 50% of melanomas. Inhibitors of BRAF and MEK can induce regression of melanomas that harbor a BRAF mutation. Three BRAF inhibitors, vemurafenib, dabrafenib, and encorafenib, have been approved for the treatment of patients whose melanomas harbor a mutation at position 600 in BRAF. Monotherapy with BRAF inhibitors has been supplanted with com­ bined BRAF and MEK inhibition to address the rapid adaptation of melanomas that use MAP kinase pathway reactivation to facilitate growth when BRAF is inhibited. Combined therapy with BRAF and MEK inhibitors (dabrafenib and trametinib, vemurafenib with cobimetinib, or encorafenib and binimetinib) improved progres­ sion-free and overall survival compared to monotherapy with a BRAF inhibitor. Long-term results of inhibition of the MAP kinase pathway confirm that some patients achieve long intervals of dis­ ease control, yet the major limitation of both monotherapy and combined therapy appears to be the acquisition of resistance. The mechanisms of resistance are diverse and reflect the genomic het­ erogeneity of melanoma; however, most instances involve reactiva­ tion of the MAPK pathway, often through RAS mutations or mutant BRAF amplification. Patients who develop resistance to BRAF and MEK inhibition are candidates for immunotherapy or clinical trials. Targeted therapy is accompanied by manageable side effects that differ from those experienced during immunotherapy. Headache, pyrexia, and arthralgias are common. A class-specific side effect of BRAF inhibitor monotherapy is the development of hyperprolifera­ tive skin lesions, including well-differentiated squamous cell skin cancers (SCCs) in up to 25% of patients. Paradoxical activation of the MAP kinase pathway occurs from BRAF inhibitor–mediated changes in BRAF wild-type cells, and the activation is blocked by MEK inhibitor, which explains why these lesions are infrequent during combined therapy. Metastases from treatment-induced SCCs have not been reported, and BRAF and MEK inhibitors can be continued safely following simple excision of the SCCs. Cardiac and ocular toxicities, although infrequent, can occur with BRAF and MEK inhibitors and require medical evaluation, management, and usually discontinuation of targeted therapy. CHAPTER 81 Cancer of the Skin Activating mutations in the c-kit receptor tyrosine kinase are found in a minority of cutaneous melanomas with chronic sun dam­ age but are more common in mucosal and acral lentiginous subtypes. When activating mutations of c-kit are present, imatinib therapy can achieve clinically meaningful responses, similar to gastrointestinal stromal tumors. The probability of objective response in patients whose melanomas harbor a c-kit mutation is 29%, although most responses are transient. N-RAS mutations occur in 15–20% of mela­ nomas. At present, there are no effective targeted agents for these patients, but N-RAS inhibitors are being investigated in clinical trials. Targeting proteins that are differentially expressed on melanoma has been the basis for many clinical trials investigating vaccines and engineered biologics. An engineered bispecific fusion protein targeting gp100 on melanoma and CD3 on T cells, called teben­ tafusp, has garnered FDA approval for the treatment of metastatic uveal melanoma in patients who have the HLA-A*02.01 tissue type. Uveal melanoma is an aggressive melanoma subtype with a propensity for metastasis to the liver and a much lower probability of response to checkpoint immunotherapy than cutaneous melano­ mas. Objective response to tebentafusp is <10%, but overall survival and progression-free survival are significantly improved compared to checkpoint immunotherapy. Other systemic therapies used to treat stage IV melanoma patients include high-dose interleukin 2, which is also associated with dura­ ble remissions in some patients. Chemotherapy using dacarbazine or taxanes is infrequently used and confers no survival benefit. INITIAL APPROACH TO PATIENT WITH METASTATIC DISEASE Upon diagnosis of stage IV disease, a sample of the patient’s tumor should be submitted for molecular testing to determine whether a BRAF or c-kit mutation is present. Analysis of a metastatic lesion biopsy is preferred, but any sample will suffice because there is little discordance between primary and metastatic lesions. Treatment algorithms start with determining the melanoma’s BRAF status. For BRAF wild-type tumors, immunotherapy is recommended. The best sequence of targeted therapy and immunotherapy in patients with BRAF-mutated melanomas has been controversial. A randomized study that compared anti-CTLA-4 plus anti-PD-1 followed by BRAF/MEK targeted therapy at progression to the opposite sequence in patients with advanced melanoma showed that immunotherapy followed by targeted therapy conferred sta­ tistically significant better overall survival at 2 years and a trend toward better progression-free survival. Toxicities were similar comparing the treatment sequences. The patient’s history, includ­ ing sites of disease, symptom burden, and history of autoimmune conditions, influences the final recommendation for immuno­ therapy or targeted therapy, but survival data favor the initial use of combined checkpoint immunotherapy in the advanced disease setting. Despite improvements in therapy, most patients with meta­ static melanoma will not be cured, so enrollment in a clinical trial is always an important consideration. Many will be poor candidates for therapy because of extensive disease burden, poor performance status, or concomitant illness; thus, the timely integration of pallia­ tive care and hospice remains an important element of care. FOLLOW-UP AND SURVIVORSHIP Skin examination and surveillance at least once a year are recom­ mended for all patients with melanoma. Routine blood work and imaging for patients with stages IA–IIA (NCCN low risk) disease is not recommended unless symptoms are present. Surveillance diag­ nostic imaging can be considered in patients with stages IIB–III (NCCN high risk) disease but is mainly reserved for patients with signs or symptoms of recurrent disease or to follow response to ther­ apy. The NCCN does not recommend surveillance imaging in asymp­ tomatic patients who had advanced melanoma and are free of disease 5 or more years out from treatment. For stage-specific recommenda­ tions, please consult the NCCN guidelines (see “Further Reading”). PART 4 Oncology and Hematology The increasing incidence of melanoma has been met with more interest in advocacy and survivorship. Several national and inter­ national advocacy groups have called attention to issues such as genetic screening, sun awareness, and the care of chronic treat­ ment-related side effects. These include, but are not limited to, skin changes (such as vitiligo), lymphedema, neuropathies, and gastrointestinal and endocrine disorders. Lymphedema can now be managed in specialty clinics that offer support, nonsurgical treat­ ments, and newer surgical therapies such as lymphovenous bypass and vascularized lymph node transplants. NONMELANOMA SKIN CANCERS NMSCs (mostly SCCs and basal cell cancer [BCC]) are the most com­ mon cancers in the United States. Although tumor registries do not routinely gather data on the incidence of NMSCs, it is estimated that the annual incidence is more than 5.3 million cases in the United States; SCCs and BCCs account for 80 and 18%, respectively. While less com­ mon, the incidence of Merkel cell carcinoma (MCC) has tripled over the past 20 years. There are now an estimated 2600 cases per year with an annual increase in incidence of 8%. NMSCs can metastasize, but MCCs do this most commonly, with sentinel lymph node positivity rates of 25% (compared to 12–19% for melanoma) and mortality rates approaching 33% at 3 years. SCCs, particularly those with high-risk features, can also metastasize and account for 2400 deaths annually. Recent advances in systemic therapy using checkpoint antibodies have improved survival in patients with advanced NMSCs. ■ ■PATHOPHYSIOLOGY AND ETIOLOGY Like melanoma, the most significant cause of NMSCs is UVR, with a dose-response relationship between tanning bed use and the incidence of NMSC. As few as four tanning bed visits per year confers a 15% increase in BCC and an 11% increase in SCC. The risk of lip or oral SCC is increased with cigarette smoking and, like SCC of the ear, has a worse prognosis than SCC found on other body sites. Human papillomavi­ ruses and UVR may act as co-carcinogens. Inherited disorders of DNA repair, such as xeroderma pigmentosum, are associated with a greatly increased incidence of skin cancer and help to establish the link between UV-induced DNA damage, inadequate DNA repair, and skin cancer. The genes associated with UV damage in SCC include p53 and N-RAS, whereas BCC is primarily associated with damage to hedgehog signaling pathway (Hh) genes, which lead to basal cell proliferation. This is usually the result of loss of function of the tumor-suppressor patched homolog 1 (PTCH1), which normally inhibits the signaling of smoothened homolog (SMO). Immunosuppression has also been associated with the development of NMSCs; chronically immunosuppressed solid organ transplant recipients have a 65-fold increase in SCC and a 10-fold increase in BCC. The frequency of skin cancer is proportional to the level and duration of immunosuppression and the extent of sun exposure before and after transplantation. SCCs in this population are particularly aggressive, demonstrating higher rates of local recurrence, metastasis, and mortal­ ity. Tumor necrosis factor (TNF) antagonist therapy of inflammatory bowel disease and autoimmune disorders, such as rheumatoid and psoriatic arthritis, may also confer an increased risk of NMSC. Other risk factors for NMSCs include HIV infection, ionizing radiation, thermal burn scars, BRAF inhibitor monotherapy, and chronic ulcerations. Albinism, xeroderma pigmentosum, Muir-Torre syndrome, Rombo’s syndrome, Bazex-Dupré-Christol syndrome, dys­ keratosis congenita, and basal cell nevus syndrome (Gorlin syndrome) also increase the incidence of NMSC. Although MCC is also clearly related to UV exposure, age, and immunosuppression, this neural crest–derived cancer also appears to have a viral etiology; an oncogenic Merkel cell polyomavirus (MCPyV) is present in 80% of tumors. In patients with MCPyV-positive tumors, there is inactivation of tumor-suppressor genes, specifically the p53 transcription factor and retinoblastoma protein (Rb). In addition, the viral large T antigen is expressed on tumor cells, and many patients have detectable cellular or humoral immune responses to polyoma viral proteins, although this immune response is insufficient to eradi­ cate the malignancy. ■ ■CLINICAL PRESENTATION Basal Cell Carcinoma  BCC arises from epidermal basal cells or the follicular bulge. The least invasive of BCC subtypes, superficial BCC, consists of often subtle, erythematous scaling plaques that slowly enlarge and are most commonly seen on the trunk and proximal extremities (Fig. 81-3). This subtype may be confused with benign inflammatory dermatoses, especially nummular eczema and psoriasis or premalignant actinic keratoses. BCC also can present as a small, slowly growing, pearly nodule, often with tortuous telangiectatic vessels on its surface, rolled borders, and a central crust (nodular BCC). The occasional pres­ ence of melanin in this variant of nodular BCC (pigmented BCC) may lead to confusion with melanoma. Morpheaform (fibrosing), infiltrative, and micronodular BCC, the most invasive and potentially aggressive subtypes, manifest as solitary, flat or slightly depressed, indurated whit­ ish, yellowish, or pink scar-like plaques. Borders are typically indistinct, and lesions can be subtle; thus, delay in treatment is common, and tumors can be more extensive than expected clinically. Squamous Cell Carcinoma  Primary cutaneous SCC is a malig­ nant neoplasm of keratinizing epidermal cells that has a variable clini­ cal course, ranging from indolent to rapid growth, with the potential to metastasize to regional and distant sites. Commonly, SCC appears as an ulcerated erythematous nodule or superficial erosion on sun-exposed skin of the head, neck, trunk, and extremities (Fig. 81-4). It may also appear as a banal, firm, dome-shaped papule or rough textured plaque. It is commonly mistaken for a wart or callous when the inflamma­ tory response to the lesion is minimal. Dotted or coiled vessels are a hallmark of SCC when viewed through a dermatoscope. The margins of this tumor may be ill defined, and fixation to underlying structures may occur (“tethering”). A very rapidly growing low-grade form of SCC, called keratoacan­ thoma (KA), typically appears as a large dome-shaped papule with a central keratotic crater. Some KAs regress spontaneously without ther­ apy, but because progression to metastatic SCC has been documented, A B C FIGURE 81-3  Clinical, dermascopic, and confocal diagnostic findings of basal cell carcinoma. A. Typical basal cell carcinoma with skin-colored, slightly translucent rolled borders and a small central erosion on chronically sun-damaged skin of the lateral posterior shoulder. B. Dermoscopic image of the same lesion as in panel A clearly revealing the central erosion and classic gray, nonreticular globular structures of melanophages that characterize BCC. C. In vivo reflectance confocal microscopy of the same lesion as in panel A showing typical nests of dermal basaloid cells (*) with classic cleft formation around the nests. (Photos courtesy of Dr. Alexander Witkowski and Dr. Joanna Ludzik, © Copyright 2022 Oregon Health & Science University [OHSU].) KAs should be treated in the same manner as other types of cutaneous SCC. KAs occur in 15–25% of patients receiving monotherapy with a BRAF inhibitor. Actinic keratoses and cheilitis (actinic keratoses on the lip), both premalignant forms of SCC, present as hyperkeratotic papules on sun-exposed areas. Malignant transformation occurs in 0.25–20% of untreated lesions. SCC in situ, also called Bowen’s disease, is the intraepidermal form of SCC and usually presents as a scaling, ery­ thematous plaque. SCC in situ most commonly arises on sun-damaged skin but can occur anywhere on the body. Bowen’s disease occurring secondary to infection with human papillomavirus can arise on skin with minimal or no prior sun exposure, such as the buttock or poste­ rior thigh. Treatment of premalignant and in situ lesions reduces the subsequent risk of invasive disease. Merkel Cell Carcinoma  MCC, also known as cutaneous apu­ doma, primary neuroendocrine carcinoma of the skin, primary small-cell carcinoma of the skin, and trabecular carcinoma of the skin, arises from Merkel cells, which are neuroendocrine skin cells that act as pressure receptors. Like other skin cancers, MCCs most commonly arise as visible skin lesions, usually as raised, flesh-colored nodules or masses; they can also be red or blue in color and vary in size from 0.5 to >5 cm in diameter and may enlarge rapidly. Although MCCs may arise almost anywhere on the body, they are most often found in sunexposed areas such as the head, neck, or extremities. They can also be found around the anus and on eyelids. The common clinical features of MCC can be summarized by the acronym AEIOU: asymptomatic/ nontender, expand rapidly, immune suppression, older than 50 years, and ultraviolet-exposed site. ■ ■NATURAL HISTORY Basal Cell Carcinoma  The natural history of BCC is that of a slowly enlarging, locally invasive neoplasm. The degree of local destruction and risk of recurrence vary with the size, duration, loca­ tion, and histologic subtype of the tumor. Location on the central face, ears, or scalp may portend a higher risk. Small nodular, pigmented, cystic, or superficial BCCs respond well to most treatments. Large lesions and micronodular, infiltrative, and morpheaform subtypes may be more aggressive. The metastatic potential of BCC is low (0.1%) in immunocompetent patients, but the risk of recurrence or a new pri­ mary NMSC is about 40% over 5 years. CHAPTER 81 Cancer of the Skin Squamous Cell Carcinoma  The natural history of SCC depends on tumor and host characteristics. Tumors arising on sun-damaged skin have a lower metastatic potential than do those on non-sun-exposed areas. Cutaneous SCC metastasizes in 0.3–5.2% of individuals, most frequently to regional lymph nodes. Tumors occurring on the lower lip and ear develop regional metastases in 13 and 11% of patients, respec­ tively, whereas the metastatic potential of SCC arising in scars, chronic ulcerations, and genital or mucosal surfaces is higher. Recurrent SCC has a 30% probability for metastatic spread. Large, poorly differenti­ ated, deep tumors with perineural or lymphatic invasion, multifocal tumors, and those arising in immunosuppressed patients often behave aggressively. Merkel Cell Carcinoma  MCCs usually present locally yet have a high probability of spread to regional lymph nodes and distant sites. Molecular markers of neuroendocrine origin such as synaptophysin or chromogranin A are useful to diagnose MCC. Unlike other neuroen­ docrine tumors, such as small-cell lung cancer (SCLC), MCCs are not associated with measurable hormone secretion or endocrine syndromes. Survival with MCC depends on extent of disease: 90% of patients with local disease are cured, whereas 52% with nodal involvement and 10% with distant disease survive. MCC has its own tumor-node-metastasis (TNM) staging system, which incorporates tumor size (<2 cm vs >2 cm), nodal status (which can be determined by SLNB for clinically negative nodes), and the presence of distant metastases. Independent of stage, the prognosis of MCC is improved if the tumor cells contain virus, express RB protein, and exhibit intratumoral CD8+ T lymphocyte infiltration. p63 expression, lymphovascular infiltrative pattern, and concomitant immunosuppression (e.g., organ transplant, HIV infection, and certain cancers) portend a worse prognosis. TREATMENT Basal Cell, Squamous Cell, and Merkel Cell Carcinoma BASAL CELL CARCINOMA Treatment for BCC includes electrodesiccation and curettage (ED&C), excision, cryosurgery, radiation therapy (RT), laser ther­ apy, MMS, topical 5-fluorouracil, photodynamic therapy (PDT), and topical immunomodulators, such as imiquimod. The choice PART 4 Oncology and Hematology A B C D E F G H I A B C D E F G H I FIGURE 81-4  Progression of basal cell (BCC) and squamous cell carcinoma (SCC). A. Superficial BCC; note salmon pink color, rolled boarder, erosions, and a gray central globule. B. Nodular BCC; note shiny, slightly pearly character with prominent arborizing vessels. C. Eroded BCC with serous and sanguinous crusting. D. Multiple actinic keratoses; note flat lesions are early, and thicker lesions may require biopsy to discriminate between advanced actinic keratosis versus early SCC. E. Superficial SCC. F. Keratoacanthoma (well-differentiated SCC). G. Mucocutaneous SCC in a high-risk area on the lower lip. H. Cutaneous SCC. I. Large exophytic SCC on the wrist. (Photos courtesy of the Dr. Leonard Swinyer Collection, © Copyright 2020 University of Utah and Oregon Health & Science University.) of therapy depends on tumor characteristics including depth and location, patient age, medical status, and patient preference. ED&C remains the most frequent treatment for superficial, minimally invasive nodular BCCs and low-risk tumors (e.g., a small tumor of a less aggressive subtype in a favorable location without terminal hairs). Wide local excision with standard margins is usually selected for invasive, ill-defined, and more aggressive subtypes of tumors or for cosmetic reasons. MMS, a specialized type of surgical excision that provides the best method for tumor removal while preserv­ ing uninvolved tissue, is associated with cure rates of >98%. It is the preferred modality for lesions that are recurrent, in high-risk or cosmetically sensitive locations (including recurrent tumors in these locations), and for which maximal tissue conservation is critical (e.g., the eyelids, lips, ears, nose, and digits). RT can cure patients not considered surgical candidates and can be used as a surgical adjunct in high-risk tumors. Imiquimod can be used to treat superficial and smaller nodular BCCs, although it is not FDA approved for nodular BCC. Topical 5-fluorouracil therapy should be limited to superficial BCC. PDT, which uses selective activation of a photoactive drug by visible light, has been used in patients with numerous tumors. Intralesional therapy (5-fluorouracil or interferon) can also be employed. Like RT, it remains an option for selected patients who cannot or will not undergo surgery. Systemic therapy with a targeted hedgehog pathway inhibitor, such as vis­ modegib or sonidegib, is indicated for patients with metastatic or advanced BCC that has recurred after local therapy and who are not candidates for surgery or RT. Targeted therapy does not cure patients with BCC but induces regression in approximately 50% of patients with a median duration of response of 9–12 months in patients with metastatic disease and ~2 years in patients with locally advanced disease. Checkpoint immunotherapy using cemiplimab can be offered to BCC patients who progress after targeted therapy. SQUAMOUS CELL CARCINOMA The principles for surgical management of SCC are the same as for BCC. Cemiplimab, a monoclonal antibody targeting PD-1, has become the systemic therapy of choice, inducing tumor regression in 47% of patients with advanced disease. Neoadjuvant cemiplimab has been given in stage II, III and IV SCC and is associated with a >50% probability of pathologic complete response and is becoming a standard of care in patients with very-high-risk presentations and/ or who have disease that may be technically difficult to resect. SCC and KAs that develop in patients receiving BRAF-targeted therapy should be excised, after which BRAF therapy can be continued. MERKEL CELL CARCINOMA The epidemiology, clinical features, and treatments for MCC over­ lap those for melanoma and NMSC. Early-stage MCCs may be cured with wide local excision of the primary tumor and nodal staging with SLNB. Like SCLCs, MCC is sensitive to radiation, PD1-directed immunotherapy, and platinum-based chemotherapy. RT is often used as postoperative adjuvant therapy at both the primary excision and SLNB sites, although its use may be withheld around sensitive areas such as the eyelids and hands and after a negative SLNB. For nonsensitive areas, RT may allow for primary excision margins smaller than the traditionally recommended 2-cm radial margins. When a positive sentinel node is found, adjuvant RT, close observation, and clinical trials investigating immunotherapy are favored over completion nodal dissection. For patients with metastatic disease, immunotherapy has sup­ planted chemotherapy. Avelumab (anti-PD-L1) therapy led to objective responses in 33% of patients with advanced MCC; 82% of the responses were durable. Pembrolizumab has an objective response >50% in patients with MCPyV-associated and nonvirus-associated advanced MCC resulting in a median duration of response approaching 2 years. Clinical trials should be offered to MCC patients who progress after checkpoint therapy and whose functional status can support additional treatment. Follow-up of patients with MCC is based on stage and risk. Rou­ tine skin exams by a dermatologist familiar with MCC and regular examinations of the nodal basins are recommended. Antibody serum titers to MCPyV should be obtained in newly diagnosed MCC patients. The test can be used to follow patients for relapse if the titer is elevated at baseline and returns to normal after A C F D B E G FIGURE 81-5  Other malignant cutaneous tumors. A. Patch stage mycosis fungoides (variant of cutaneous T-cell lymphoma). B. Tumor stage mycosis fungoides. C. Extramammary Paget’s disease. D. Merkel cell carcinoma. E. Dermatofibrosarcoma protuberans. F. and G. Kaposi’s sarcoma. (Parts A, B, and D-G photos courtesy of the Dr. Leonard Swinyer Collection, © Copyright 2020 University of Utah and Oregon Health & Science University. Part C photo courtesy Dr. Justin Leitenberger, © Copyright 2022 Oregon Health & Science University [OHSU].) treatment. Conversely, if the titer is elevated but does not return to normal after treatment, imaging should be obtained to look for occult metastases. ■ ■PREVENTION The principles for prevention are those described for melanoma earlier. Unique strategies for NMSC include active surveillance for patients on immunosuppressive medications or BRAF-targeted therapy. Chemopro­ phylaxis using synthetic retinoids and immunosuppression reduction when possible may be useful in controlling new lesions and managing patients with multiple tumors. Nicotinamide 500 mg BID may be used in patients with large numbers of actinic keratoses and SCCs to reduce the development and/or progression of disease. Field therapy with topi­ cal 5-fluorouracil (with or without calcipotriol), ingenol mebutate, or imiquimod can reduce transformation to SCC in patients with severely sun-damaged skin and numerous premalignant actinic keratoses. Older, immunosuppressed patients should be managed with the lowest doses of immunosuppression possible and encouraged to be particularly care­ ful to minimize UV exposure. Earlier biopsy of unusual-appearing skin lesions may lead to better control of aggressive lesions. ■ ■OTHER NONMELANOMA CUTANEOUS MALIGNANCIES Neoplasms of cutaneous adnexae and sarcomas of fibrous, mesenchy­ mal, fatty, and vascular tissues make up the remaining 1–2% of NMSCs (Fig. 81-5). Lymphomas of B- or T-cell origin can also manifest in the skin and can mimic benign conditions such as psoriasis and eczema. CHAPTER 81 Extramammary Paget’s disease is an uncommon apocrine malig­ nancy arising from stem cells of the epidermis that is characterized Cancer of the Skin # 11 - 82 Head and Neck Cancer ### 82 Head and Neck Cancer histologically by the presence of Paget cells. These tumors present as moist erythematous patches on anogenital or axillary skin of the elderly. Outcomes are generally good with surgery, and 5-year diseasespecific survival is 95% with localized disease. Advanced age and extensive disease at presentation confer poorer prognosis. RT or topical imiquimod can be considered for more extensive disease. Local management may be challenging because these tumors often extend far beyond clinical margins; surgical excision with MMS has the high­ est cure rates. Similarly, MMS is the treatment of choice in other rare cutaneous tumors with extensive subclinical extension such as derma­ tofibrosarcoma protuberans. Kaposi’s sarcoma (KS) is a soft tissue sarcoma of vascular origin that is induced by the human herpesvirus 8. The incidence of KS increased dramatically during the AIDS epidemic but has now decreased tenfold with the institution of highly active antiretroviral therapy. Acknowledgment Walter Urba, MD, PhD, provided valued feedback and suggested improvements to this chapter. Clinical photos were generously provided from the OHSU Swinyer Collection (Leonard Swinyer, MD) and by Drs. Elizabeth Berry, Alexander Witkowski, Joanna Ludzik, Debbie Miller, Alison Skalet, and Justin Leitenberger. Dermoscopic images were pro­ vided by Elizabeth Berry, Alexander Witkowski, Joanna Ludzik, and Debbie Miller. Reflectance confocal microscopy images were provided by Drs. Alexander Witkowski and Joanna Ludzik. PART 4 Oncology and Hematology ■ ■FURTHER READING Atkins ME et al: Combination dabrafenib and trametinib versus combination nivolumab and ipilimumab for patients with advanced BRAF-mutant melanoma: The DREAMseq trial—ECOG-ACRIN EA6134. J Clin Oncol 41:186, 2022. Elder DE et al: The 2018 World Health Organization classification of cutaneous, mucosal, and uveal melanoma. Arch Pathol Lab Med 44:500, 2020. Faries MD et al: Completion dissection or observation for sentinel-node metastasis in melanoma. N Engl J Med 376:2211, 2017. Harms PW et al: The biology and treatment of Merkel cell carcinoma: Current understanding and research priorities. Nat Rev Clin Oncol 15:763, 2018. National Comprehensive Cancer Network: NCCN clinical practice guidelines in oncology (NCCN guidelines): Melanoma. Available from https://www.nccn.org/professionals/physician_gls/pdf/melanoma. pdf. Tawbi HA et al: Relatlimab and nivolumab versus nivolumab in untreated advanced melanoma. N Engl J Med 386:24, 2022. Wu YP et al: A systematic review of interventions to improve adher­ ence to melanoma preventive behaviors for individuals at elevated risk. Prev Med 88:153, 2016. Everett E. Vokes Head and Neck Cancer Epithelial carcinomas of the head and neck arise from the mucosal surfaces in the head and neck and typically are squamous cell in origin. This category includes tumors of the paranasal sinuses, the oral cavity, and the nasopharynx, oropharynx, hypopharynx, and larynx. Tumors of the salivary glands differ from the more common carcinomas of the head and neck in etiology, histopathology, clinical presentation, and therapy. They are rare and histologically highly heterogeneous. Thyroid malignancies are described in Chap. 397. ■ ■INCIDENCE AND EPIDEMIOLOGY The number of new cases of head and neck cancers (oral cavity, phar­ ynx, and larynx) in the United States was estimated at 66,920 in 2023, accounting for about 6% of adult malignancies; estimated deaths were 15,400. The worldwide incidence exceeds half a million cases annually. In North America and Europe, the tumors usually arise from the oral cavity, oropharynx, or larynx. The incidence of oropharyngeal cancers has been increasing in Western countries. Nasopharyngeal cancer is endemic in East Asia and some Mediterranean countries. ■ ■ETIOLOGY AND GENETICS Alcohol and tobacco use are the most significant environmental risk factors for head and neck cancer, and when used together, they act synergistically. Smokeless tobacco is an etiologic agent for oral can­ cers. Other potential carcinogens include marijuana and occupational exposures such as nickel refining, exposure to textile fibers, and woodworking. Some head and neck cancers have a viral etiology. Epstein-Barr virus (EBV) infection is frequently associated with nasopharyngeal cancer, especially in endemic areas. EBV antibody titers can be measured to screen high-risk populations and are under investigation to monitor treatment response. Nasopharyngeal cancer has also been associated with consumption of salted fish and indoor pollution. In Western countries, the human papillomavirus (HPV) is associ­ ated with a rising incidence of tumors arising from the oropharynx, that is, the tonsillar bed and base of tongue. Over 50% of oropha­ ryngeal tumors are caused by HPV in the United States, and in many urban centers, this proportion is higher. HPV-16 is the dominant viral subtype, although HPV-18 and other oncogenic subtypes are seen as well. Alcohol- and tobacco-related cancers, on the other hand, have decreased in incidence. HPV-related oropharyngeal cancer occurs in a younger patient population and is associated with increased num­ bers of sexual partners and oral sexual practices. It is associated with a better prognosis, especially for nonsmokers. Vaccination with the nine-valent HPV vaccine may prevent the disease but is not likely to result in a lower incidence for several decades due to long latency of the carcinogenic process. Dietary factors may contribute. The incidence of head and neck cancer is higher in people with the lowest consumption of fruits and vegetables. Certain vitamins, including carotenoids, may be protective if included in a balanced diet. Supplements of retinoids, such as cisretinoic acid, have not been shown to prevent head and neck cancers (or lung cancer) and may increase the risk in active smokers. No spe­ cific risk factors or environmental carcinogens have been identified for salivary gland tumors. ■ ■HISTOPATHOLOGY, CARCINOGENESIS, AND MOLECULAR BIOLOGY Squamous cell head and neck cancers are divided into well-differentiated, moderately well-differentiated, and poorly differentiated categories. Poorly differentiated tumors have a worse prognosis than well-differen­ tiated tumors. For nasopharyngeal cancers, the less common differenti­ ated squamous cell carcinoma is distinguished from nonkeratinizing and undifferentiated carcinoma (lymphoepithelioma) that contains infiltrating lymphocytes and is commonly associated with EBV. Salivary gland tumors can arise from the major (parotid, subman­ dibular, sublingual) or minor salivary glands (located in the submucosa of the upper aerodigestive tract). Most parotid tumors are benign, but half of submandibular and sublingual gland tumors and most minor salivary gland tumors are malignant. Malignant tumors include muco­ epidermoid and adenoid cystic carcinomas and adenocarcinomas. The mucosal surface of the entire pharynx is exposed to alcohol- and tobacco-related carcinogens and is at risk for the development of a premalignant or malignant lesion. Erythroplakia (a red patch) or leukoplakia (a white patch) can be histopathologically classified as hyperplasia, dysplasia, carcinoma in situ, or carcinoma. However, most head and neck cancer patients do not present with a known his­ tory of premalignant lesions. Multiple synchronous or metachronous cancers can also be observed. In fact, over time, patients with treated early-stage tobacco- and alcohol-related head and neck cancer are at greater risk of dying from a second malignancy than from a recurrence of the primary disease. Second head and neck malignancies are usually not therapy induced; they reflect the exposure of the upper aerodigestive mucosa to the same carcinogens that caused the first cancer. These second prima­ ries develop in the head and neck area, the lung, or the esophagus. Thus, computed tomography (CT) screening for lung cancer in heavy smokers who have already developed a head and neck cancer is rec­ ommended. Rarely, patients can develop a radiation therapy–induced sarcoma after having undergone prior radiotherapy for a head and neck cancer. Much progress has been made in describing the molecular features of head and neck cancer. These features have allowed investigators to describe the genetic and epigenetic alterations and the mutational spectrum of these tumors. Early reports demonstrated frequent overex­ pression of the epidermal growth factor receptor (EGFR). Overexpres­ sion was shown to correlate with poor prognosis. However, it has not proved to be a good predictor of tumor response to EGFR inhibitors, which are active in only about 10–15% of patients as single agents. Complex genetic analyses, including those by The Cancer Genome Atlas project, have been performed. p53 mutations are found fre­ quently with other major affected oncogenic driver pathways including the mitotic signaling and Notch pathways and cell cycle regulation in HPV-negative tumors. HPV oncogenes act through direct inhibition of the p53 and RB tumor-suppressor genes, thereby initiating the carcino­ genic process. HRAS mutations are detected in 4–8% of patients with recurrent head and neck cancer and may be therapeutically targetable in a small patient subset. While overall mutation rates are similar in HPV-positive and carcinogen-induced tumors, the specific mutational signature of HPV-positive tumors differs, with frequent alteration of the PI3K pathway and occasional mutations in KRAS. Overall, these alterations affect mitogenic signaling, genetic stability, cellular prolif­ eration, and differentiation. ■ ■CLINICAL PRESENTATION AND DIFFERENTIAL DIAGNOSIS Most tobacco-related head and neck cancers occur in patients older than age 60 years. HPV-related malignancies are frequently diagnosed in younger patients, usually in their forties or fifties, whereas EBVrelated nasopharyngeal cancer can occur at all ages, including in teen­ agers. The manifestations vary according to the stage and primary site of the tumor. Patients with nonspecific signs and symptoms in the head and neck area should be evaluated with a thorough otolaryngologic examination, particularly if symptoms persist longer than 2–4 weeks. Males are more frequently affected than women by head and neck can­ cers, including HPV-positive tumors. Cancer of the nasopharynx typically does not cause early symptoms. However, it may cause unilateral serous otitis media due to obstruc­ tion of the eustachian tube, unilateral or bilateral nasal obstruction, or epistaxis. Advanced nasopharyngeal carcinoma causes neuropathies of the cranial nerves due to skull base involvement. Carcinomas of the oral cavity present as nonhealing ulcers, changes in the fit of dentures, or painful lesions and masses. Tumors of the tongue base or oropharynx can cause decreased tongue mobility and alterations in speech. Cancers of the oropharynx or hypopharynx rarely cause early symptoms, but they may cause sore throat and/or otalgia. HPV-related tumors frequently present with neck lymphade­ nopathy as the first sign. Hoarseness may be an early symptom of laryngeal cancer, and persistent hoarseness requires referral to a specialist for indirect laryn­ goscopy and/or radiographic studies. If a head and neck lesion treated initially with antibiotics does not resolve in a short period, further workup is indicated; to simply continue the antibiotic treatment may be to lose the chance of early diagnosis of a malignancy. Advanced head and neck cancers in any location can cause severe pain, otalgia, airway obstruction, cranial neuropathies, trismus, ody­ nophagia, dysphagia, decreased tongue mobility, fistulas, skin involve­ ment, and massive cervical lymphadenopathy, which may be unilateral Physical Examination in Office FNA or excision of lymph node If lymphoma, sarcoma, or salivary gland tumor If squamous cell carcinoma Panendoscopy and directed biopsies. Search for occult primary with biopsies of tonsils, nasopharynx, base of tongue, and pyriform sinus. Specific workup Stage-specific multimodality therapy Consider curative neck dissection Postoperative radiotherapy or chemoradiotherapy CHAPTER 82 FIGURE 82-1  Evaluation of a patient with cervical adenopathy without a primary mucosal lesion; a diagnostic workup. FNA, fine-needle aspiration. or bilateral. Some patients have enlarged lymph nodes even though no primary lesion can be detected by endoscopy or biopsy; these patients are considered to have carcinoma of unknown primary (Fig. 82-1). Tonsillectomy and directed biopsies of the base of tongue can iden­ tify a small primary tumor that frequently will be HPV related. If the enlarged nodes are located in the upper neck and the tumor cells are of squamous cell histology, the malignancy probably arose from a muco­ sal surface in the head or neck. Tumor cells in supraclavicular lymph nodes may also arise from a primary site in the chest or abdomen. Head and Neck Cancer The physical examination should include inspection of all visible mucosal surfaces and palpation of the floor of the mouth and of the tongue and neck. In addition to a tumor, leukoplakia (a white muco­ sal patch) or erythroplakia (a red mucosal patch) may be observed; these “premalignant” lesions can represent hyperplasia, dysplasia, or carcinoma in situ and require biopsy. Further examination should be performed by a specialist. Additional staging procedures include CT or MRI of the head and neck to identify the extent of the disease. Patients with lymph node involvement should have CT scan of the chest and upper abdomen to screen for distant metastases. In heavy smokers, the CT scan of the chest can also serve as a screening tool to rule out a second lung primary tumor. A positron emission tomogra­ phy (PET) scan can help to identify or exclude distant metastases. CT and PET scans may also be useful in evaluating response to therapy. The definitive staging procedure is an endoscopic examination under anesthesia, which may include laryngoscopy, esophagoscopy, and bronchoscopy; during this procedure, multiple biopsy samples are obtained to establish a primary diagnosis, define the extent of primary disease, and identify any additional premalignant lesions or second primaries. Head and neck tumors are classified according to the tumor-nodemetastasis (TNM) system of the American Joint Committee on Cancer (AJCC) (Fig. 82-2). This classification varies according to the specific anatomic subsite. In general, primary tumors are classified as T1 to T3 by increasing size, whereas T4 usually represents invasion of another structure such as bone, muscle, or root of tongue. Lymph nodes are staged by size, number, and location (ipsilateral vs contralateral to the primary). Overt distant metastases are found in <10% of patients at initial diagnosis and are more common in patients with advanced lymph node stage; microscopic involvement of the lungs, bones, or liver is more common, particularly in patients with advanced neck lymph node disease. HPV-related oropharyngeal malignancies have consistently been shown to have a better prognosis, and in the eighth Definition of TNM Stage I T1 N0- Tumor ≤2 cm in greatest dimension ≤5 mm depth of invasion (DOI) Stage II T2 Tumor ≥2 cm but not more than 4 cm in greatest dimension OR DOI >5 mm and ≤10 mm PART 4 Oncology and Hematology Stage III T3 Tumor ≥4 cm OR DOI >10 mm Stage IVA T4a N2a- Tumor invades skin, mandible, ear canal, fascial nerve, and/or floor of mouth Stage IVB T4b T4b Tumor invades skull base and/or pterygoid plates and/or encases carotid artery Stage IVC M1 M1 Any T Any N FIGURE 82-2  Tumor-node-metastasis (TNM) staging system. (Figure based on the AJCC Cancer Staging Manual, 8th edition.) edition of the AJCC staging manual, a separate staging system that takes into account the more favorable outlook of these patients has been included. According to this system, patients with advanced nodal stage can still be considered to have the equivalent of an overall early stage (and associated good prognosis). In patients with lymph node involvement and no visible primary, the diagnosis should be made by fine-needle aspiration or by DOI = depth of invasion Stage groupings T1 N0 N0 M0 No regional lymph node metastasis T2 N0 N0 M0 No regional lymph node metastasis N0- N1 T3 N0 M0 Metastasis in a single ipsilateral lymph node, ≤3 cm in greateast dimension N1- N1 T1 M0 N1 T2 M0 T3 N1 M0 ≤3 cm N2 T4a N0 M0 Metastasis in a single ipsilateral lymph node, >3 cm but ≤6 cm T4a N1 M0 T1 N2 M0 Metastasis in multiple ipsilateral lymph nodes, none >6 cm N2b- T2 N2 M0 Metastasis in bilateral or contralateral lymph nodes, none >6 cm N2c- T3 N2 M0 T4a N2 M0 ≤6 cm N3 M0 Any N Metastasis in a lymph node >6 cm in greatest dimension or clinically overt extranodal extension N3- N3 M0 Any T >6 cm lymph node excision (especially if only a single node appears involved) (Fig. 82-1). If the results indicate squamous cell carcinoma, a panen­ doscopy should be performed, with biopsy of all suspicious-appearing areas and directed biopsies of common primary sites, such as the nasopharynx, tonsil, tongue base, and pyriform sinus. HPV-positive tumors especially can have small primary tumors that spread early to locoregional lymph nodes. TREATMENT Head and Neck Cancer Patients with head and neck cancer can be grossly categorized into three clinical groups: those with localized disease, those with locally or regionally advanced disease (lymph node positive), and those with recurrent and/or metastatic disease below the neck. Comorbidities associated with tobacco and alcohol abuse can affect treatment outcome and define long-term risks for patients who are cured of their disease. LOCALIZED DISEASE Nearly one-third of patients have localized disease, that is, T1 or T2 (stage I or stage II) lesions without detectable lymph node involve­ ment or distant metastases. These patients are treated with curative intent by either surgery or radiation therapy. The choice of modality differs according to anatomic location and institutional expertise. Radiation therapy is often preferred for laryngeal cancer to preserve voice function, and surgery is preferred for small lesions in the oral cavity to avoid the long-term complications of radiation, such as xerostomia and osteoradionecrosis and dental decay. Randomized data have shown that a prophylactic staging neck dissection should be part of the surgical procedure to eliminate occult nodal meta­ static disease. Overall 5-year survival is 60–90%. Most recurrences occur within the first 2 years following diagnosis and are usually local. LOCALLY OR REGIONALLY ADVANCED DISEASE Locally or regionally advanced disease—disease with a large pri­ mary tumor and/or cervical lymph node metastases—is the stage of presentation for >50% of patients. Such patients can also be treated with curative intent, but not usually with surgery or radiation therapy alone. Combined-modality therapy, including surgery and/ or radiation therapy and chemotherapy, is most successful. Che­ motherapy can be administered as induction chemotherapy (che­ motherapy before surgery and/or radiotherapy) or as concomitant (simultaneous) chemotherapy and radiation therapy. The latter is most commonly used and supported by the best evidence. Five-year survival rates exceed 50% in many trials, but part of this increased survival may be due to an increasing fraction of study populations with HPV-related tumors who carry a better prognosis. HPV test­ ing of newly diagnosed tumors should be performed for patients with oropharyngeal tumors at the time of diagnosis. Clinical trials for HPV-related tumors are focused on exploring reductions in treatment intensity, especially radiation dose, in order to ameliorate long-term toxicities (fibrosis, swallowing dysfunction). In patients with intermediate-stage tumors (stage III and early stage IV), concomitant chemoradiotherapy can be administered as a primary treatment for patients with unresectable disease, to pursue an organ-preserving approach especially for patients with laryngeal cancer (omission of surgery), or in the postoperative set­ ting for smaller resectable tumors with adverse prognostic features. Induction Chemotherapy  In this strategy, patients receive che­ motherapy (current standard is a three-drug regimen of docetaxel, cisplatin, and fluorouracil [5-FU]) before surgery and radiation therapy. Most patients who receive three cycles show tumor reduc­ tion, and the response is clinically “complete” in up to half of patients. This “sequential” multimodality therapy allows for organ preservation in patients with laryngeal and hypopharyngeal cancer and results in higher cure rates compared with radiotherapy alone. Concomitant Chemoradiotherapy  With the concomitant strategy, chemotherapy and radiation therapy are given simultaneously rather than in sequence. Tumor recurrences from head and neck cancer develop most commonly locoregionally (in the head and neck area of the primary and draining lymph nodes). The concomi­ tant approach is aimed at enhancing tumor cell killing by radiation therapy in the presence of chemotherapy (radiation enhancement) and is a conceptually attractive approach for bulky tumors. Toxicity (especially mucositis, grade 3 or 4, in 70–80%) is increased with concomitant chemoradiotherapy. However, meta-analyses of ran­ domized trials document an improvement in 5-year survival of 8% with concomitant chemotherapy and radiation therapy. Cisplatin is preferentially given weekly during a course of daily radiotherapy over a 6- to 7-week course. In addition, concomitant chemoradio­ therapy produces better laryngectomy-free survival (organ pres­ ervation) than radiation therapy alone in patients with advanced larynx cancer. For patients with advanced nasopharyngeal cancer, the addition of neoadjuvant chemotherapy before concomitant chemoradiotherapy has been adopted as standard of care leading to 5-year survival rates exceeding 80% in a Southeast Asian study. The outcome of HPV-related cancers also seems to be favorable following cisplatin-based chemoradiotherapy. However, trials sub­ stituting cisplatin with the EGFR inhibitor cetuximab in that patient population have shown inferior survival. Similarly, the investigation of immune checkpoint inhibitors in this setting has not yet led to improved outcomes. The success of concomitant chemoradiotherapy in patients with unresectable disease has led to the testing of a similar approach in patients with resected intermediate-stage disease as a postopera­ tive therapy. Concomitant chemoradiotherapy produces a signifi­ cant improvement over postoperative radiation therapy alone for patients whose tumors demonstrate higher risk features, such as extracapsular spread beyond involved lymph nodes, involvement of multiple lymph nodes, or positive margins at the primary site following surgery. CHAPTER 82 A monoclonal antibody to EGFR (cetuximab) increases sur­ vival rates when administered during radiotherapy compared with radiotherapy alone and has been considered for patients unable to tolerate concurrent chemoradiotherapy. The addition of cetuximab to standard chemoradiotherapy regimens has failed to show further improvement in survival and is not recommended. Head and Neck Cancer TREATMENT APPROACHES FOR HPV-RELATED HEAD AND NECK CANCERS Given consistent observations of high survival rates for patients with advanced HPV-related oropharyngeal tumors using combinedmodality treatment strategies, de-escalation protocols have attracted widespread interest. The goal here is to decrease the long-term morbidity resulting from high-dose radiation therapy, including extensive neck fibrosis, swallowing problems, and osteoradione­ crosis of the jaw. Current studies are investigating the use of lower radiation doses, the use of induction chemotherapy and subse­ quent omission of chemotherapy or administration of significantly reduced chemoradiation doses in very good responders, and other strategies. In addition, interest has increased in surgical approaches using robotic surgery, which allows better visualization of the base of tongue and tonsil. While technically feasible, a large number of patients with disease involving multiple lymph nodes will still require postoperative chemoradiotherapy, thus negating the goal of treatment de-escalation. At present, treatment guidelines for HPV-related tumors are identical to carcinogen-induced tumors. It is hoped that de-escalation approaches will be validated by ongoing controlled clinical trials. RECURRENT AND/OR METASTATIC DISEASE Five to 10% of patients present with metastatic disease, and 30–50% of patients with locoregionally advanced disease experience recurrence, frequently outside the head and neck region. Patients with recurrent and/or metastatic disease are, with few exceptions, treated with pal­ liative intent. Some patients may require local or regional radiation therapy for pain control, but most are given systemic therapy. Combination chemotherapy formerly was the first-line systemic therapeutic approach to patients with recurrent disease after prior curative intent surgery and/or chemoradiotherapy or those present­ ing initially with metastatic disease. In particular, a combination of cisplatin with 5-FU and cetuximab (the EXTREME regimen) was frequently used. # 12 - 83 Neoplasms of the Lung ### 83 Neoplasms of the Lung However, immunotherapies have proven to be of value in this setting. In particular, inhibitors of the immunosuppressive lym­ phocyte surface receptor (PD-1) pathway have shown activity in squamous cell cancers of the head and neck. A randomized trial evaluating the PD-1 inhibitor nivolumab versus traditional chemo­ therapy in the second-line treatment of patients with recurrent or metastatic disease showed a significant increase in 1-year survival rates with fewer severe treatment-related toxicities. In addition, some responses were of long duration, allowing a cohort of patients to live far beyond the historical median of <1 year. The PD-1 inhibitor pembrolizumab also demonstrated activity in a similarly designed randomized trial. Pembrolizumab was also compared as single-agent therapy and in combination with cisplatin and 5-FU with prior standard chemo­ therapy alone (cisplatin, 5-FU, and cetuximab). In this trial, overall survival was improved with pembrolizumab versus chemotherapy as well as with the combination of chemotherapy plus pembroli­ zumab with the relative benefit correlating with the expression of PD-L1 in the tumor tissue. Patients with tumors high in expres­ sion (PD-L1 score >20%; i.e., expression of PD-L1 on 20% of tumor cells) had a marked survival benefit with pembrolizumab as single agent, whereas patients with lower PD-L1 expression had a less impressive but still statistically significant survival benefit. For the group expressing lower levels of PD-L1, the combination of pembrolizumab with chemotherapy showed more substantial benefit. Current standard treatment therefore frequently consists of combination chemoimmunotherapy for patients with low PD-L1 expression, whereas those with higher expression can be treated with immunotherapy alone, especially if overall tumor burden is limited. Patients with no PD-L1 expression may still be treated with the prior EXTREME chemotherapy standard. Patients who experience progression after first-line chemoimmunotherapy or immunotherapy can then be treated with additional single-agent or combination chemotherapy. PART 4 Oncology and Hematology EGFR-directed therapies, including monoclonal antibodies (e.g., cetuximab) and tyrosine kinase inhibitors (TKIs) of the EGFR sig­ naling pathway (e.g., erlotinib or gefitinib), have single-agent activity of ∼10%. Side effects are usually limited to an acneiform rash and diarrhea (for the TKIs). Drugs targeting specific mutations are under investigation, and patients with HRAS-driven tumors can experience shrinkage with the farnesyltransferase inhibitor tipifarnib. COMPLICATIONS Complications from treatment of head and neck cancer are usually correlated to the extent of surgery and exposure of normal tissue structures to radiation. The extent of surgery can be limited or surgery can be completely replaced by use of chemotherapy and radiation therapy as the primary approach. Acute complications of radiation include mucositis and dysphagia. Long-term complica­ tions include xerostomia, loss of taste, decreased tongue mobility, second malignancies, dysphagia, and neck fibrosis. The compli­ cations of chemotherapy vary with the regimen used but usually include myelosuppression, mucositis, nausea and vomiting, and nephrotoxicity (with cisplatin). The mucosal side effects of therapy can lead to malnutrition and dehydration. Many centers address issues of dentition before starting treatment, and some place feeding tubes to ensure control of hydration and nutrition intake. About 50% of patients develop hypothyroidism from the treatment; thus, thyroid function should be monitored. ■ ■SALIVARY GLAND TUMORS Most benign salivary gland tumors are treated with surgical excision, and patients with invasive salivary gland tumors are treated with surgery and radiation therapy. These tumors may recur regionally; adenoid cystic carcinoma has a tendency to recur along the nerve tracks. Distant metastases may occur as late as 10–20 years after the initial diagnosis. For metastatic disease, therapy is given with pallia­ tive intent, usually chemotherapy with doxorubicin and/or a platinum agent by itself or in combination with a taxane. Identification of novel agents with activity in these tumors is a high priority. It is hoped that comprehensive genomic characterization of these rare tumors will facilitate these efforts. ■ ■FURTHER READING Agrawal N et al: Exome sequencing of head and neck squamous cell carcinoma reveals inactivating mutations in NOTCH1. Science 333:1154, 2011. Burtness B et al: Pembrolizumab alone or with chemotherapy for recurrent/metastatic head and neck squamous cell carcinoma in KEYNOTE-048: Subgroup analysis by programmed death ligand-1 combined positive score. J Clin Oncol 40:2321, 2022. Chan KCA et al: Analysis of plasma Epstein-Barr virus DNA to screen for nasopharyngeal cancer. N Engl J Med 377:513, 2017. D’Cruz AK et al: Elective versus therapeutic neck dissection in nodenegative oral cancer. N Engl J Med 373:521, 2015. Ho AL et al: Tipifarnib in head and neck squamous cell carcinoma with HRAS mutations. J Clin Oncol 39:1856, 2021. Kang H et al: Whole-exome sequencing of salivary gland mucoepider­ moid carcinoma. Clin Cancer Res 23:283, 2017. Lechner M et al: HPV-associated oropharyngeal cancer: Epidemiology, molecular biology and clinical management. Nat Rev Clin Oncol 19:306, 2022. Mehanna H et al: De-escalation after DE-ESCALATE and RTOG 1016: A Head and Neck Cancer Intergroup framework for future deescalation studies. J Clin Oncol 38:2552, 2020. Mody MD et al: Head and neck cancer. Lancet 398:2289, 2021. Zhang Y et al: Final overall survival analysis of gemcitabine and cisplatin induction chemotherapy in nasopharyngeal carcinoma: A multicenter, randomized phase III trial. J Clin Oncol 40:2420, 2022. Eric K. Singhi, Christine M. Lovly Neoplasms of the Lung Over 2.2 million people globally were diagnosed with lung cancer in 2020, ranking it as the second most frequently diagnosed cancer. Although maintaining its status as the leading cause of cancer-related deaths worldwide, claiming 1.8 million lives in the same year, a note­ worthy decline in lung cancer fatalities has emerged. This shift is credited to advancements in screening and early detection methods, improved therapeutic strategies, and a reduction in tobacco usage. Tobacco consumption, established as the primary cause of lung cancer in the mid-twentieth century, was solidified with the U.S. Sur­ geon General’s 1964 report on the health effects of tobacco smoking. After the report, cigarette use declined in North America and parts of Europe, and with it, so did the incidence of lung cancer. Although tobacco smoking remains the leading global cause of lung cancer, accounting for about two-thirds of lung cancer deaths worldwide, ~65% of new lung cancer diagnoses in the United States are in indi­ viduals with a former smoking history (smoked ≥100 cigarettes per lifetime, quit ≥1 year) or individuals with no smoking history (smoked <100 cigarettes per lifetime), with one in five women and one in 12 men diagnosed having never smoked. EPIDEMIOLOGY Lung cancer is the most common cause of cancer death among American men and women. Approximately 235,000 individuals will be diagnosed with lung cancer in the United States in 2024, and >125,000 individuals will die from the disease. Lung cancer is less common below age 40, with rates increasing until age 80, after which the rate tapers off. The projected lifetime probability of developing lung cancer is estimated at 1 in 16 for males and 1 in 17 for females as of 2023. Since 2006, there has been a steady decline in the incidence of lung cancer, with an annual decrease of 2.5% in men and 1% in women. Despite this positive trend, disparities persist. The incidence of lung cancer varies among racial and ethnic groups, with African Americans exhibiting the highest age-adjusted rates. While the excess in age-adjusted rates among African Americans occurs only among men, examination of age-specific rates shows that below age 50, mortality from lung cancer is >25% higher among African-American women compared to their Caucasian counterparts. Additionally, African Americans face a 19% lower likelihood of receiv­ ing definitive surgical treatment, 11% higher likelihood of not receiv­ ing any treatment, and a 16% lower likelihood of surviving 5 years compared to their Caucasian counterparts. Incidence and mortality rates among Hispanics and Native and Asian Americans are ∼40–50% of those among Caucasians. Consideration of these disparities prompts reflection on potential equitable improvements in lung cancer care. ■ ■RISK FACTORS Persons who smoke have a 10-fold or greater increased risk of develop­ ing lung cancer compared to those who have never smoked. A largescale genomic study suggested that one genetic mutation is induced for every 15 cigarettes smoked. The risk of lung cancer is lower among per­ sons who quit smoking than among those who continue smoking. The size of the lung cancer risk reduction increases with the length of time the person has quit smoking, although even long-term former smok­ ers have higher risks of lung cancer than those who never smoked. Cigarette smoking has been shown to increase the risk of all major types of lung cancer. Environmental tobacco smoke (ETS) or secondhand smoke is also an established cause of lung cancer. The risk from ETS is less than from active smoking, with about a 20–30% increase in lung cancer observed among never smokers married for many years to smokers, in comparison to the 2000% increase among continuing active smokers. The impact on the development of lung cancer among users of alternate nicotine delivery devices (e-cigarettes or vaping) is undefined. While one large, randomized study demonstrated the supe­ riority of e-cigarettes compared to traditional nicotine replacement therapy in aiding smoking cessation, e-cigarette– or vaping-associated lung injury (EVALI) is an emerging phenomenon that poses risks that may counterbalance the potential benefit in helping patients reduce traditional cigarette consumption and lung cancer risk. Although cigarette smoking is the cause of the majority of lung cancers, several other risk factors have been identified, including occupational exposure to asbestos, arsenic, bischloromethyl ether, hexavalent chromium, mustard gas, nickel (as in certain nickel-refining processes), and polycyclic aromatic hydrocarbons. Ionizing radiation is also an established lung carcinogen, most con­ vincingly demonstrated from studies showing increased rates of lung cancer among survivors of the atom bombs dropped on Hiroshima and Nagasaki and large excesses among workers exposed to alpha irradiation from radon in underground uranium mining. Prolonged exposure to low-level radon in homes might impart a risk of lung cancer equal to or greater than that of ETS. Prior lung diseases such as chronic bronchitis, emphysema, and tuberculosis have been linked to increased risks of lung cancer as well. The risk of lung cancer appears to be higher among individuals with low fruit and vegetable intake during adulthood. This observation led to hypotheses that specific nutrients, in particular retinoids and carotenoids, might have chemopreventative effects for lung cancer. However, randomized trials failed to validate this hypothesis. Smoking Cessation  Given the undeniable link between cigarette smoking and lung cancer, physicians must promote complete tobacco avoidance. Stopping tobacco use before middle age avoids >90% of the lung cancer risk attributable to tobacco. Importantly, smoking cessa­ tion can even be beneficial in individuals with an established diagnosis of lung cancer, as it is associated with improved overall survival, fewer side effects from therapy, and an overall improvement in quality of life. Consequently, it is important to promote smoking cessation even after the diagnosis of lung cancer is established. This remains a challenge as ~30% of patients continue to smoke even after receiving a diagnosis of lung cancer. Physicians need to understand the essential elements of smoking cessation therapy. Self-help strategies alone only marginally affect quit rates, whereas individual and combined pharmacotherapies in com­ bination with counseling can significantly increase rates of cessation. Therapy with an antidepressant (e.g., bupropion) and nicotine replace­ ment therapy (varenicline, a α4β2 nicotinic acetylcholine receptor par­ tial agonist) are approved by the U.S. Food and Drug Administration (FDA) as first-line treatments for nicotine dependence. In a random­ ized trial, varenicline was shown to be more efficacious than bupropion or placebo. Prolonged use of varenicline beyond the initial induction phase proved useful in maintaining smoking abstinence. Clonidine and nortriptyline are recommended as second-line treatments. A role for e-cigarettes has not been definitively established (Chap. 465). Inherited Predisposition to Lung Cancer  Exposure to envi­ ronmental carcinogens, such as those found in tobacco smoke, induces or facilitates the transformation from bronchoepithelial cells to a malignant phenotype. The contribution of carcinogens to trans­ formation is modulated by polymorphic variations in genes that affect aspects of carcinogen metabolism. Certain genetic polymorphisms of the P450 enzyme system, specifically CYP1A1, and chromosome fra­ gility are associated with the development of lung cancer. These genetic variations occur at relatively high frequency in the population, but their contribution to an individual’s lung cancer risk is generally low. However, because of their population frequency, the overall impact on lung cancer risk could be high. CHAPTER 83 Neoplasms of the Lung First-degree relatives of lung cancer probands have a two- to three­ fold excess risk of lung cancer and other cancers, many of which are not smoking-related. These data suggest that specific genes and/or genetic variants may contribute to susceptibility to lung cancer. However, very few such genes have yet been identified. Individuals with inherited mutations in RB (patients with retinoblastoma living to adulthood) and TP53 (patients with Li-Fraumeni syndrome) genes may develop lung cancer. Common gene variants involved in lung cancer have identified three separate loci that are associated with lung cancer (5p15, 6p21, and 15q25) and include genes that regulate acetylcholine nicotinic receptors and telomerase production. A rare germline muta­ tion (T790M) involving the epidermal growth factor receptor (EGFR) maybe be linked to lung cancer susceptibility in never smokers. Like­ wise, a susceptibility locus on chromosome 6q greatly increases lung cancer risk among light and never smokers. A study involving 7700 patients diagnosed with primary lung cancer who underwent germ­ line DNA sequencing and exon-level copy number analysis revealed that 14.9% of them had one or more clinically significant pathogenic germline variants; these variants were mainly found in DNA damage repair genes, suggesting a higher prevalence of pathogenic germline mutations in patients with primary lung cancer than previously sus­ pected. Additionally, the Taiwan National Lung Cancer Early Detection Program, launched in July 2022, provided screening for nonsmoker patients with a positive family history of lung cancer in their firstdegree relatives; this program demonstrated a 1.4% cancer detection rate among individuals with a family history of lung cancer. Despite this progress in identifying heritable risk factors for lung cancer, there is still significant work to be done. Currently, no molecular criteria are suitable for selecting patients for more intense screening programs or specific chemopreventive strategies. ■ ■PATHOLOGY The World Health Organization (WHO) defines lung cancer as tumors arising from the respiratory epithelium (bronchi, bronchioles, and alveoli). The WHO classification system divides epithelial lung cancers into four major cell types: small-cell lung cancer (SCLC), adenocar­ cinoma, squamous cell carcinoma, and large-cell carcinoma; the lat­ ter three types are collectively known as non-small-cell carcinomas (NSCLCs) (Fig. 83-1). Small-cell carcinomas consist of small cells with scant cytoplasm, ill-defined cell borders, finely granular nuclear Non-Small-Cell Lung Cancer Squamous cell Adenocarcinoma Large-cell carcinoma Adenocarcinoma Squamous Large Small Small-Cell Lung Cancer FIGURE 83-1  Histologic subsets of lung cancer. chromatin, absent or inconspicuous nucleoli, and a high mitotic count. SCLC may be distinguished from NSCLC by the presence of neuro­ endocrine markers including CD56, neural cell adhesion molecule (NCAM), synaptophysin, chromogranin, and insulinoma-associated protein 1 (INSM1). Adenocarcinomas possess glandular differentiation or mucin production and may show acinar, papillary, lepidic, or solid features or a mixture of these patterns. Squamous cell carcinomas of the lung are morphologically identical to extrapulmonary squamous cell carcinomas and cannot be distinguished by immunohistochemis­ try alone. Squamous cell tumors show keratinization and/or intercel­ lular bridges that arise from bronchial epithelium. The tumor consists of sheets of cells rather than the three-dimensional groups of cells characteristic of adenocarcinomas. Large-cell carcinomas compose <10% of lung carcinomas. These tumors lack the cytologic and archi­ tectural features of small-cell carcinoma and glandular or squamous differentiation. Together, these four histologic types account for ∼90% of all epithelial lung cancers. PART 4 Oncology and Hematology All histologic types of lung cancer can develop in current and former smokers, although squamous and small-cell carcinomas are more com­ monly associated with tobacco use. With the decline in cigarette con­ sumption, adenocarcinoma has become the most frequent histologic subtype of lung cancer in the United States. In lifetime, never smokers or former light smokers (<10 pack-year history), women, and younger adults (<60 years), adenocarcinoma tends to be the most common form of lung cancer. In addition to distinguishing between SCLC and NSCLC, because these tumors have quite different natural histories and therapeutic approaches (see below), it is necessary to classify whether NSCLC is squamous or nonsquamous. The classification system, developed jointly by the International Association for the Study of Lung Cancer, the American Thoracic Society, and the European Respiratory Society, provides an integrated approach to the classification of lung adenocar­ cinoma that includes clinical, molecular, radiographic, and pathologic information. Even with advances in lung cancer screening and early detection, many lung cancers are still detected in an advanced stage and may be diagnosed based on small biopsies or cytologic specimens, rendering clear histologic distinctions difficult. In such cases, particularly in patients with advanced-stage disease, a repeat biopsy is recommended to obtain additional tissue for further clarification. The distinction between squamous and nonsquamous lung cancer is viewed as criti­ cal to optimal therapeutic decision-making, and a diagnosis of nonsmall-cell carcinoma, not otherwise specified is no longer considered acceptable. This distinction can be achieved using a single marker for adenocarcinoma (thyroid transcription factor-1 or napsin-A) plus a squamous marker (p40 or p63) and/or mucin stains. If tissue is limited and a clear morphologic pattern is evident, a diagnosis can be made without immunohistochemistry staining. In addition to determining histologic subtype, preservation of sufficient specimen material for appropriate molecular testing and programmed death ligand 1 (PD-L1) testing necessary to help guide therapeutic decision-making is recom­ mended (see below). The terms adenocarcinoma in situ and minimally invasive adeno­ carcinoma are now recommended for small solitary adenocarcinomas (≤3 cm) with either pure lepidic growth (term used to describe singlelayered growth of atypical cuboidal cells coating the alveolar walls) or predominant lepidic growth with ≤5 mm invasion. Individuals with these entities experience 100% or near 100% 5-year disease-free survival with complete tumor resection. Invasive adenocarcinomas, representing >70–90% of surgically resected lung adenocarcinomas, are now classified by their predominant pattern: lepidic, acinar, papil­ lary, and solid patterns. In general, lepidic-predominant subtype has a favorable prognosis, acinar and papillary have an intermediate progno­ sis, and solid-predominant has a poor prognosis. The terms signet ring and clear cell adenocarcinoma have been eliminated from the variants of invasive lung adenocarcinoma, whereas the term micropapillary, a subtype with a particularly poor prognosis, has been added. Because of prognostic implications, squamous cell carcinoma has also been modi­ fied to consist of keratinizing, nonkeratinizing, and basaloid, analogous to head and neck cancers. ■ ■IMMUNOHISTOCHEMISTRY The diagnosis of lung cancer most often rests on the morphologic or cytologic features correlated with clinical and radiographic findings. Immunohistochemistry may be used to verify neuroendocrine differ­ entiation within a tumor, with markers such as neuron-specific enolase (NSE), CD56 or NCAM, synaptophysin, chromogranin, and Leu7. Immunohistochemistry is also helpful in differentiating primary from metastatic adenocarcinomas; thyroid transcription factor-1 (TTF-1), identified in tumors of thyroid and pulmonary origin, is positive in >70% of pulmonary adenocarcinomas and is a reliable indicator of pri­ mary lung cancer, provided a thyroid primary has been excluded. A nega­ tive TTF-1, however, does not exclude the possibility of a lung primary. TTF-1 is also positive in neuroendocrine tumors of pulmonary and extrapulmonary origin. Napsin-A (Nap-A) is an aspartic protease that plays an important role in maturation of surfactant B7 and is expressed in cytoplasm of type II pneumocytes. In several studies, Nap-A has been reported in >90% of primary lung adenocarcinomas. Notably, a combination of Nap-A and TTF-1 is useful in distinguishing primary lung adenocarcinoma (Nap-A positive, TTF-1 positive) from primary lung squamous cell carcinoma (Nap-A negative, TTF-1 negative) and primary SCLC (Nap-A negative, TTF-1 positive). Cytokeratins (CK) 7 and 20 used in combination can help narrow the differential diagnosis; nonsquamous NSCLC, SCLC, and mesothelioma may stain positive for CK7 and negative for CK20, whereas squamous cell lung cancer often will be both CK7 and CK20 negative. p63 is a useful marker for the detection of NSCLCs with squamous differentiation when used in cytologic pulmonary samples. Mesothelioma can be easily identified ultrastructurally, but it has historically been difficult to differentiate from adenocarcinoma through morphology and immunohistochemi­ cal staining. Several markers in the past few years have proven to be more helpful including CK5/6, calretinin, and Wilms tumor gene-1 (WT-1), all of which show positivity in mesothelioma. ■ ■MOLECULAR PATHOGENESIS As proposed by Hanahan and Weinberg, virtually all cancer cells acquire six hallmark capabilities: self-sufficiency in growth signals, insensitivity to antigrowth signals, evading apoptosis, limitless replica­ tive potential, sustained angiogenesis, and tissue invasion and metas­ tasis. The order in which these hallmark capabilities are acquired is variable. Events leading to acquisition of these hallmarks vary widely, although broadly, cancers arise as a result of accumulations of gain-offunction mutations in oncogenes and loss-of-function mutations in tumor-suppressor genes. Further complicating the study of lung cancer, the sequence of events that leads to disease is clearly different for the various histopathologic entities. For cancers in general, one theory holds that a small subset of the cells within a tumor (i.e., “stem cells”) are responsible for the full malignant behavior of the tumor. As part of this concept, the large bulk of the cells in a cancer are “offspring” of these cancer stem cells. While clonally related to the cancer stem cell subpopulation, most cells by themselves cannot regenerate the full malignant phenotype. The stem cell concept may explain the failure of standard medi­ cal therapies to eradicate lung cancers, even when there is a clinical complete response. Disease recurs because therapies do not eliminate the stem cell component, which may be more resistant to therapy. Precise human lung cancer stem cells have yet to be identified. Among lung cancer histologies, adenocarcinomas have been the most extensively catalogued for recur­ rent genomic gains and losses as well as for somatic mutations (Fig. 83-2, Table 83-1). While multiple dif­ ferent kinds of aberrations have been found, a major class involves “driver mutations,” which are mutations that occur in genes encoding signaling proteins that, when aberrant, drive initiation and maintenance of tumor cells. Importantly, driver mutations can serve as a potential Achilles’ heels for tumors, if their gene products can be targeted appropriately. Several driver oncogenes have been described in NSCLC. These include activating mutations in receptor tyrosine kinases, including EGFR, ERBB2/HER2, and MET, and activating mutations in intracellular signaling proteins, such as KRAS and BRAF. Additionally, chromosomal rearrangements may also produce driver oncogenes in lung tumors, such as those chromosomal rear­ rangements leading to activation of the ALK, ROS1, RET, and NTRK tyrosine kinases. Each of these so-called “driver oncogenes” represents a distinct molecular cohort of lung cancer, with differing prevalence and varying levels of evidence regarding clinical actionability. So-called “targeted therapies” directed against these aberrantly activated onco­ genes are discussed below. It is worth noting that most of these driver oncogenes are enriched in nonsquamous tumors. ROS1 RET MEK1 NRAS NTRK1 PIK3CA FIGURE 83-2  Driver mutations in lung adenocarcinomas. Three potential molecular targets have been identified in squamous cell lung carcinomas: FGFR1 amplification, DDR2 mutations, and PIK3CA mutations/PTEN loss, as well as BRAF and MET (Table 83-1). A large number of tumor-suppressor genes have also been identi­ fied that are inactivated during the pathogenesis of lung cancer. These include TP53, RB1, RASSF1A, CDKN2A/B, LKB1 (STK11), and FHIT. Nearly 90% of SCLCs harbor mutations in TP53 and RB1. Several tumor-suppressor genes on chromosome 3p appear to be involved in nearly all lung cancers. Allelic loss of this region occurs very early in lung cancer pathogenesis, including in histologically normal smokingdamaged lung epithelium. EARLY DETECTION AND SCREENING In lung cancer, clinical outcome is related to the stage at diagnosis, and hence, it is generally assumed that early detection of occult tumors will lead to improved survival. Early detection is a process that involves screening tests, surveillance, diagnosis, and early treatment. Screening refers to the use of tests across a healthy population in order to identify individuals who harbor asymptomatic disease. For a screening pro­ gram to be successful, the target population must be a high-risk popu­ lation; the test must be sensitive, specific, accessible, and cost effective; and effective treatment must be available that can reduce mortality. With any screening procedure, it is important to consider the pos­ sible influence of lead-time bias (detecting the cancer earlier without an effect on survival), length-time bias (indolent cancers are detected on screening and may not affect survival, whereas aggressive cancers are likely to cause symptoms earlier in patients and are less likely to be detected), and overdiagnosis (diagnosing cancers so slow growing that they are unlikely to cause the death of the patient). AKT1 BRAF ALK AKT1 ALK BRAF EGFR EGFR HER2 Unknown KRAS MEK1 HER2 MET NRAS NTRK1 PIK3CA KRAS RET CHAPTER 83 ROS1 Unknown MET Neoplasms of the Lung Because a majority of lung cancer patients present with advanced disease beyond the scope of surgical resection, the value of screening for this condition is debated. Indeed, randomized controlled trials conducted in the 1960s to 1980s using screening chest x-rays (CXR), with or without sputum cytology, reported no impact on lung can­ cer–specific mortality in patients characterized as high risk (males age ≥45 years with a smoking history). These studies have been criticized for their design, statistical analyses, and outdated imaging modalities. In contrast to CXR, low-dose, noncontrast, thin-slice spiral chest com­ puted tomography (LDCT) has emerged as an effective tool to screen for lung cancer. In nonrandomized studies conducted in the 1990s, LDCT scans were shown to detect more lung nodules and cancers than standard CXR in selected high-risk populations (e.g., age ≥60 years and a smoking history of ≥10 pack-years). Notably, up to 85% of the lung cancers discovered in these trials were classified as stage I disease and therefore considered potentially curable with surgical resection. These data prompted the National Cancer Institute (NCI) to initi­ ate the National Lung Screening Trial (NLST), a randomized study designed to determine if LDCT screening could reduce mortality TABLE 83-1  Genetic Alterations with Existing Therapies in Non-SmallCell Lung Cancer (NSCLC) FREQUENCY IN NSCLC TYPICAL HISTOLOGY GENE ALTERATION ALK Rearrangement 3–7% Adenocarcinoma BRAF Mutation 1–3% Adenocarcinoma EGFR Mutation 10–35% Adenocarcinoma HER2 Mutation 2–4% Adenocarcinoma KRAS Mutation 15–25% Adenocarcinoma MET Amplification 2–4% Adenocarcinoma NRAS Mutation 1% Adenocarcinoma NTRK Rearrangement 1–2% Adenocarcinoma RET Rearrangement 1–2% Adenocarcinoma ROS1 Rearrangement 1–2% Adenocarcinoma from lung cancer in high-risk populations as compared with standard posterior anterior CXR. High-risk patients were defined as individuals between 55 and 74 years of age with a ≥30 pack-year history of cigarette smoking; former smokers must have quit within the previous 15 years. Excluded from the trial were individuals with a previous lung cancer diagnosis, a history of hemoptysis, an unexplained weight loss of >15 lb in the preceding year, or a chest computed tomography (CT) within 18 months of enrollment. A total of 53,454 persons were enrolled and randomized to annual screening yearly for 3 years (LDCT screening, n = 26,722; CXR screening, n = 26,732). Any noncalcified nodule measuring ≥4 mm in any diameter found on LDCT and CXR images with any noncalcified nodule or mass was classified as “positive.” Participating radiologists had the option of not calling a final screen positive if a noncalcified nodule had been stable on the three screening examinations. Overall, 39.1% of participants in the LDCT group and 16% in the CXR group had at least one positive screening result. Of those who screened positive, the false-positive rate was 96.4% in the LDCT group and 94.5% in the CXR group. This was consistent across all three rounds. In the LDCT group, 1060 cancers were identified compared with 941 cancers in the CXR group (645 vs 572 per 100,000 person-years; relative risk [RR], 1.13; 95% confidence interval [CI], 1.03–1.23). Nearly twice as many stage IA cancers were detected in the LDCT group compared with the CXR group (40% vs 21%). The overall rates of lung cancer death were 247 and 309 deaths per 100,000 participants in the LDCT and CXR groups, respectively, representing a 20% reduction in lung cancer mortality in the LDCT-screened popula­ tion (95% CI, 6.8–26.7%; p = .004). Compared with the CXR group, the rate of death in the LDCT group from any cause was reduced by 6.7% (95% CI, 1.2–13.6%; p = .02). The number needed to screen (NNTS) to prevent one lung cancer death was calculated to be 320. PART 4 Oncology and Hematology The Nelson study was a second randomized trial comparing no screening to CT scans at baseline and in years 1, 3, and 5.5 in 13,195 men and 2594 women. Participants were 50–75 years of age and were current and former smokers with 10 years or less of cessation who smoked >15 cigarettes a day for >25 years or >10 cigarettes daily for >30 years. Participants were selected from four regions in the Nether­ lands or Belgium and were excluded if they were in moderate or bad self-reported health, were unable to climb two flights of stairs, had a body weight >140 kg, had a CT of the chest within the past year or a history of lung cancer <5 years ago or were still under treatment, or had current or past renal cell carcinoma, melanoma, or breast cancer. The hazard ratio for lung cancer mortality at 10 years was 0.74 (95% CI, 0.60–0.91; p = .003) and 0.61 (95% CI, 0.35–1.04; p = .0543) in men and women, respectively. These two trials have validated the use of annual CT scans for early detection of lung cancer in high-risk populations. LDCT screening for lung cancer comes with known risks includ­ ing a high rate of false-positive results, false-negative results, potential for unnecessary follow-up testing, radiation exposure, overdiagnosis, changes in anxiety level and quality of life, and substantial financial costs. One of the greatest challenges confronting the use of CT screen­ ing, in addition to its implementation, is the high false-positive rate. False positives can have a substantial impact on patients through the expense and risk of unneeded further evaluation and emotional stress. The management of these patients usually consists of serial CT scans over time to see if the nodules grow, attempted fine-needle aspirates, or surgical resection. At approximately $300 per scan (NCI estimated cost), the outlay for initial LDCT alone could run into the billions of dollars annually, an expense that only further escalates when factoring in various downstream expenditures an individual might incur in the assessment of positive findings. A formal cost-effectiveness analysis of the NLST demonstrated differences between sex, age, and current smoking status and the method of follow-up. Despite some questions, annual LDCT screening has been recommended for all patients meet­ ing the following updated criteria from the U.S. Preventive Services Task Force as of 2021: individuals aged 50–80 years old with a 20-packyear or greater smoking history who currently smoke or formerly smoked within the past 15 years. When discussing the option of LDCT screening, use of absolute risks rather than relative risks is helpful because studies indicate the public can process absolute terminology TABLE 83-2  The Benefits and Harms of LDCT Screening for Lung Cancer Based on NLST Data   LDCT CXR Benefits: How did CT scans help compared to CXR? 4 in 1000 fewer died from lung cancer 13 in 1000 17 in 1000 5 in 1000 fewer died from all causes 70 in 1000 75 in 1000 Harms: What problems did CT scans cause compared to CXR? 223 in 1000 had at least 1 false alarm 365 in 1000 142 in 1000 18 in 1000 had a false alarm leading to an invasive procedure 25 in 1000 7 in 1000 2 in 1000 had a major complication from an invasive procedure 3 in 1000 1 in 1000 Abbreviations: CT, computed tomography; CXR, chest x-ray; LDCT, low-dose computed tomography; NLST, National Lung Screening Trial. Source: From S Woloshin: Cancer screening campaigns getting past uninformative persuasion. N Engl J Med 367:1167, 2012. Copyright © (2012) Massachusetts Medical Society. Reprinted with permission from Massachusetts Medical Society. more effectively than relative risk projections. A useful guide has been developed by the NCI to help patients and physicians assess the ben­ efits and harms of LDCT screening for lung cancer (Table 83-2). CLINICAL MANIFESTATIONS Over half of all patients diagnosed with lung cancer present with locally advanced or metastatic disease at the time of diagnosis. The majority of patients present with signs, symptoms, or laboratory abnormalities that can be attributed to the primary lesion, local tumor growth, inva­ sion or obstruction of adjacent structures, growth at distant metastatic sites, or a paraneoplastic syndrome (Tables 83-3 and 83-4). A history of chronic cough with or without hemoptysis in a current or former smoker with chronic obstructive pulmonary disease (COPD) age 40 years or older should prompt a thorough investigation for lung cancer even in the face of a normal CXR. A persistent pneumonia without consti­ tutional symptoms and unresponsive to repeated courses of antibiotics also should prompt an evaluation for the underlying cause. Lung can­ cer occurring in individuals who have never smoked is more prevalent in, though not limited to, women and East Asians. These patients also typically present at a younger age than their smoking counterparts at the time of diagnosis. The clinical presentation of lung cancer in never smokers tends to mirror that of current and former smokers. Patients with central or endobronchial growth of the primary tumor may present with cough, hemoptysis, wheeze, stridor, dyspnea, or postobstructive pneumonia. Peripheral growth of the primary tumor may cause pain from pleural or chest wall involvement, dyspnea on a restrictive basis, and symptoms of a lung abscess resulting from tumor TABLE 83-3  Presenting Signs and Symptoms of Lung Cancer SYMPTOM AND SIGNS RANGE OF FREQUENCY Cough 8–75% Weight loss 0–68% Dyspnea 3–60% Chest pain 20–49% Hemoptysis 6–35% Bone pain 6–25% Clubbing 0–20% Fever 0–20% Weakness 0–10% Superior vena cava obstruction 0–4% Dysphagia 0–2% Wheezing and stridor 0–2% Source: Reproduced with permission from MA Beckles: Initial evaluation of the patient with lung cancer. Symptoms, signs, laboratory tests, and paraneoplastic syndromes. Chest 123:97, 2003. TABLE 83-4  Clinical Findings Suggestive of Metastatic Disease Symptoms elicited in history • Constitutional: weight loss >10 lb • Musculoskeletal: pain • Neurologic: headaches, syncope, seizures, extremity weakness, recent change in mental status Signs found on physical examination • Lymphadenopathy (>1 cm) • Hoarseness, superior vena cava syndrome • Bone tenderness • Hepatomegaly (>13 cm span) • Focal neurologic signs, papilledema • Soft-tissue mass Routine laboratory tests • Hematocrit, <40% in men; <35% in women • Elevated alkaline phosphatase, GGT, SGOT, and calcium levels Abbreviations: GGT, gamma-glutamyltransferase; SGOT, serum glutamic-oxaloacetic transaminase. Source: Reproduced with permission from GA Silvestri et al: The noninvasive staging of non-small cell lung cancer. Chest 123:147S, 2003. cavitation. Regional spread of tumor in the thorax (by contiguous growth or by metastasis to regional lymph nodes) may cause tra­ cheal obstruction, esophageal compression with dysphagia, recurrent laryngeal nerve paralysis with hoarseness, phrenic nerve palsy with elevation of the hemidiaphragm and dyspnea, and sympathetic nerve paralysis with Horner’s syndrome (i.e., enophthalmos, ptosis, miosis, and anhidrosis). Malignant pleural effusions can cause pain, dyspnea, or cough. Pancoast (or superior sulcus tumor) syndromes result from local extension of a tumor growing in the apex of the lung with involve­ ment of the eighth cervical and first and second thoracic nerves, and present with shoulder pain that characteristically radiates in the ulnar distribution of the arm, often with radiologic destruction of the first and second ribs. Often Horner’s syndrome and Pancoast syndrome coexist. Other problems of regional spread include superior vena cava syndrome from vascular obstruction; pericardial and cardiac extension with resultant tamponade, arrhythmia, or cardiac failure; lymphatic obstruction with resultant pleural effusion; and lymphangitic spread through the lungs with hypoxemia and dyspnea. In addition, lung cancer can spread transbronchially, producing tumor growth along multiple alveolar surfaces with impairment of gas exchange, respiratory insufficiency, dyspnea, hypoxemia, and sputum production. Constitu­ tional symptoms may include anorexia, weight loss, weakness, fever, and night sweats. These parameters cannot clearly distinguish SCLC from NSCLC or even from neoplasms metastatic to lungs. Extrathoracic metastatic disease is found at autopsy in >50% of patients with squamous carcinoma, 80% of patients with adenocar­ cinoma and large-cell carcinoma, and >95% of patients with SCLC. Approximately one-third of patients present with symptoms as a result of distant metastases. Lung cancer metastases may occur in virtually every organ system, and the site of metastatic involvement largely determines other symptoms. Patients with brain metastases may pres­ ent with headache, nausea and vomiting, seizures, or neurologic defi­ cits. Patients with bone metastases may present with pain, pathologic fractures, or spinal cord compression. The latter may also occur with epidural metastases. Individuals with bone marrow invasion may pres­ ent with cytopenias or leukoerythroblastosis. Those with liver metas­ tases may present with hepatomegaly, right upper quadrant pain, fever, anorexia, and weight loss. Liver dysfunction and biliary obstruction are rare. Adrenal metastases are common but rarely cause pain or adrenal insufficiency unless they are large. Paraneoplastic syndromes are common in patients with lung cancer, especially those with SCLC, and may be the presenting finding or the first sign of recurrence. In addition, paraneoplastic syndromes may mimic metastatic disease and, unless detected, lead to inappropriate palliative rather than curative treatment. Often the paraneoplastic syndrome may be relieved with successful treatment of the tumor. In some cases, the pathophysiology of the paraneoplastic syndrome is known, particularly when a hormone with biologic activity is secreted by a tumor. However, in many cases, the pathophysiology is unknown. Systemic symptoms of anorexia, cachexia, weight loss (seen in 30% of patients), fever, and suppressed immunity are paraneoplastic syndromes of unknown etiology or at least not well defined. Weight loss >10% of total body weight is considered a bad prognostic sign. Endocrine syndromes are seen in 12% of patients; hypercalcemia resulting from ectopic production of parathyroid hormone (PTH) or, more commonly, PTH-related peptide is the most common life-threatening metabolic complication of malignancy, primarily occurring with squamous cell carcinomas of the lung. Clinical symptoms include nausea, vomiting, abdominal pain, constipation, polyuria, thirst, and altered mental status. Hyponatremia may be caused by the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) or possibly atrial natri­ uretic peptide (ANP) (Chap. 98). SIADH resolves within 1–4 weeks of initiating chemotherapy in the vast majority of cases. During this period, serum sodium can usually be managed and maintained above 128 mEq/L via fluid restriction. Demeclocycline can be a useful adjunctive measure when fluid restriction alone is insufficient. Vaso­ pressin receptor antagonists like tolvaptan also have been used in the management of SIADH. However, the use of tolvaptan has significant limitations including liver injury and overly rapid correction of the hyponatremia, which can lead to irreversible neurologic injury. Like­ wise, the cost of tolvaptan may be prohibitive. Of note, patients with ectopic ANP may have worsening hyponatremia if sodium intake is not concomitantly increased. Accordingly, if hyponatremia fails to improve or worsens after 3–4 days of adequate fluid restriction, plasma levels of ANP should be measured to determine the causative syndrome. CHAPTER 83 Ectopic secretion of ACTH by SCLC and pulmonary carcinoids usually results in additional electrolyte disturbances, especially hypo­ kalemia, rather than the changes in body habitus that occur in Cush­ ing’s syndrome from a pituitary adenoma (Chap. 98). Treatment with standard medications, such as metyrapone and ketoconazole, is largely ineffective due to extremely high cortisol levels. The most effective strategy for management of the Cushing’s syndrome is effective treat­ ment of the underlying SCLC. Bilateral adrenalectomy may be consid­ ered in extreme cases. Neoplasms of the Lung Skeletal–connective tissue syndromes include clubbing in 30% of cases (usually NSCLCs) and hypertrophic primary osteoarthropathy in 1–10% of cases (usually adenocarcinomas). Patients may develop periostitis, causing pain, tenderness, and swelling over the affected bones and a positive bone scan. Neurologic–myopathic syndromes are seen in only 1% of patients but are dramatic and include the myas­ thenic Eaton-Lambert syndrome and retinal blindness with SCLC, whereas peripheral neuropathies, subacute cerebellar degeneration, cortical degeneration, and polymyositis are seen with all lung cancer types. Many of these are caused by autoimmune responses such as the development of anti-voltage-gated calcium channel antibodies in Eaton-Lambert syndrome. Patients with this disorder present with proximal muscle weakness, usually in the lower extremities, occa­ sional autonomic dysfunction, and rarely, cranial nerve symptoms or involvement of the bulbar or respiratory muscles. Depressed deep tendon reflexes are frequently present. In contrast to patients with myasthenia gravis, strength improves with serial effort. Some patients who respond to chemotherapy will have resolution of the neurologic abnormalities. Thus, chemotherapy is the initial treatment of choice. Paraneoplastic encephalomyelitis and sensory neuropathies, cerebellar degeneration, limbic encephalitis, and brainstem encephalitis occur in SCLC in association with a variety of antineuronal antibodies such as anti-Hu, anti-CRMP5, and ANNA-3. Paraneoplastic cerebellar degen­ eration may be associated with anti-Hu, anti-Yo, or P/Q calcium chan­ nel autoantibodies. Coagulation or thrombotic or other hematologic manifestations occur in 1–8% of patients and include migratory venous thrombophlebitis (Trousseau’s syndrome), nonbacterial thrombotic (marantic) endocarditis with arterial emboli, and disseminated intra­ vascular coagulation with hemorrhage, anemia, granulocytosis, and leukoerythroblastosis. Thrombotic disease complicating cancer is usu­ ally a poor prognostic sign. Cutaneous manifestations such as dermato­ myositis and acanthosis nigricans are uncommon (1%), as are the renal manifestations of nephrotic syndrome and glomerulonephritis (≤1%). DIAGNOSING LUNG CANCER Tissue sampling is required to confirm a diagnosis in all patients with suspected lung cancer. In patients with suspected metastatic disease, a biopsy of a distant site of disease is preferred for concurrent tissue and staging confirmation. Given the greater emphasis placed on molecular and PD-L1 testing for NSCLC patients, a core biopsy is preferred to ensure adequate tissue for analysis. Tumor tissue may be obtained via minimally invasive techniques such as bronchial or transbronchial biopsy during fiberoptic bronchoscopy, by fine-needle aspiration (FNA) or percutaneous biopsy using image guidance, or via endobronchial ultrasound (EBUS)-guided biopsy. Depending on the location, lymph node sampling may occur via transesophageal endoscopic ultrasound (EUS)-guided biopsy, EBUS-guided biopsy, or blind biopsy. In patients with suspected metastatic disease, a diagnosis may be confirmed by bronchoscopy, percutaneous biopsy of a soft tissue mass, lytic bone lesion, bone marrow, pleural or liver lesion, or an adequate cell block obtained from a malignant pleural effusion. In patients with a suspected malignant pleural effusion, if the initial thoracentesis is negative, repeat thoracentesis is essential. Although the majority of pleural effusions are due to malignant disease, particularly if they are exudative or bloody, some may be parapneumonic. In the absence of distant disease, such patients should be considered for possible curative treatment. The diagnostic yield of any biopsy depends on several factors including location (accessibility) of the tumor, tumor size, tumor type, and technical aspects of the diagnostic procedure including the experi­ ence level of the bronchoscopist and pathologist. In general, central lesions such as squamous cell carcinomas, small-cell carcinomas, or endobronchial lesions such as carcinoid tumors are more readily diag­ nosed by bronchoscopic examination, whereas peripheral lesions such as adenocarcinomas and large-cell carcinomas are more amenable to transthoracic biopsy. PART 4 Oncology and Hematology Biomarker testing in lung cancer plays an essential role in guiding a precision-based medicine approach for patient care. Ideally performed at the time of initial diagnosis, biomarker testing is recommended for all patients with advanced stage NSCLC by most current guidelines, with consideration for those with squamous histology. Biomarker test­ ing aims to identify specific genetic alterations, or molecular markers, within the tumor cells. Traditionally, the gold standard process involves obtaining a tissue sample from the patient, which is then subjected to advanced techniques such as next-generation sequencing (NGS) to complete multigene sequencing. By completing this testing, clinicians can discern the presence of driver oncogenes to allow for tailored treat­ ment approaches specific to the underlying molecular profile of the tumor such as with targeted therapies. Of note, immunohistochemical staining on tumor tissue should be employed for PD-L1 testing, quanti­ fied as tumor proportion score (TPS), as the level of PD-L1 expression serves as an additional crucial biomarker in lung cancer management. Advancements in the detection of circulating tumor DNA (ctDNA) have emerged as a noninvasive strategy to perform a “liquid biopsy” with a blood sample to assist in diagnosis and treatment monitoring. This strategy may be particularly useful to overcome tissue limitations, such as in cases where obtaining a tissue biopsy may be challenging or not feasible due to a tumor’s location. The role of a liquid biopsy continues to evolve, especially as the sensitivity and specificity of this biopsy strategy continue to improve. STAGING LUNG CANCER Lung cancer staging consists of two parts: first, a determination of the location of the tumor and possible metastatic sites (anatomic staging), and second, an assessment of a patient’s ability to withstand various antitumor treatments (physiologic staging). All patients with lung cancer should have a complete history and physical examination, with evaluation of all other medical problems, determination of perfor­ mance status (i.e., standardized measure assessing a patient’s physical functioning and ability to perform activities of daily living to deter­ mine their overall health and suitability for treatment), and history of weight loss. Staging with regard to a patient’s potential for surgical resection is principally applicable to NSCLC. ■ ■ANATOMIC STAGING OF PATIENTS WITH LUNG CANCER The accurate staging of patients with NSCLC is essential for deter­ mining the appropriate treatment in patients with resectable disease and for avoiding unnecessary surgical procedures in patients with advanced disease. All patients with NSCLC should undergo initial radiographic imaging with CT scan, positron emission tomography (PET), or preferably PET-CT. PET scanning attempts to identify sites of malignancy based on glucose metabolism by measuring the uptake of 18F-fluorodeoxyglucose (FDG). Rapidly dividing cells, presumably in the lung tumors, will preferentially take up 18F-FDG and appear as a “hot spot.” To date, PET has been mostly used for staging and detection of metastases in lung cancer and in the detection of nodules >15 mm in diameter. Combined 18F-FDG PET-CT imaging has been shown to improve the accuracy of staging in NSCLC compared to visual correla­ tion of PET and CT or either study alone. PET-CT has been found to be superior in identifying pathologically enlarged mediastinal lymph nodes and extrathoracic metastases. A standardized uptake value (SUV) of >2.5 on PET is highly suspicious for malignancy. False nega­ tives can be seen in diabetes, in lesions <8 mm, and in slow-growing tumors (e.g., carcinoid tumors or well-differentiated adenocarcinoma). False positives can be seen in certain infections and granulomatous disease (e.g., tuberculosis). Thus, PET should never be used alone to diagnose lung cancer, mediastinal involvement, or metastases. Confir­ mation with tissue biopsy is required. For brain metastases, magnetic resonance imaging (MRI) is the most effective method. MRI can also be useful in selected circumstances, such as superior sulcus tumors to rule out brachial plexus involvement, but in general, MRI does not play a major role in NSCLC staging. If imaging is concerning for metastatic disease, biopsy of a distant site of disease is preferred for concurrent tissue diagnosis and con­ firmation of staging. In patients in whom distant metastatic disease has been ruled out, lymph node status needs to be assessed via mini­ mally invasive techniques such as those mentioned above, including EBUS-guided mediastinal staging, and/or invasive techniques such as mediastinoscopy, mediastinotomy, thoracoscopy, or thoracotomy. Approximately one-quarter to one-half of patients diagnosed with NSCLC will have mediastinal lymph node metastases at the time of diagnosis. A standard nomenclature for referring to the location of lymph nodes involved with lung cancer has evolved (Fig. 83-3). Lymph node sampling is recommended in all patients with enlarged nodes detected by CT or PET scan and in patients with large tumors or tumors occupying the inner third of the lung. The extent of mediastinal lymph node involvement is important in determining the appropriate definitive intent treatment strategy: neoadjuvant/perioperative therapy followed by surgical resection versus surgical resection followed by adjuvant therapy versus combined chemoradiation followed by immu­ notherapy consolidation (durvalumab). In SCLC patients, current staging recommendations include a PET-CT scan and MRI of the brain (positive in 10% of asymptomatic patients). Bone marrow biopsies and aspirations are rarely performed now given the low incidence of isolated bone marrow metastases. Confirmation of metastatic disease, ipsilateral or contralateral lung nodules, or metastases beyond the mediastinum may be achieved by the same modalities recommended earlier for patients with NSCLC. If a patient has signs or symptoms of spinal cord compression (pain, weakness, paralysis, urinary retention), a spinal CT or MRI scan should be performed. If metastases are evident on imaging, a neurosurgeon should be consulted for possible palliative surgical resection and/or a radiation oncologist should be consulted for palliative radiotherapy to the site of compression. If signs or symptoms of leptomeningeal disease develop at any time in a patient with lung cancer, an MRI of the brain and spinal cord should be performed, as well as a lumbar puncture, for evaluation and detection of malignant cells in the cerebrospinal fluid. If the lumbar puncture is negative, a repeat procedure should be considered. Leptomeningeal disease remains a clinical challenge, as there is currently no approved therapy for the specific treatment of leptomeningeal disease. Superior mediastinal nodes Brachiocephalic (innominate) a. 2R Ao 4R Azygos v. 4L 10R PA N2 = single digit, ipsilateral N3 = single digit, contralateral or supraclavicular 11R 11L Aortic nodes 10L 12, 13, 14R 12, 13, 14L Inf.pulm. ligt. Inferior mediastinal nodes Ligamentum arteriosum L. pulmonary a. Phrenic n. N1 nodes Ao PA FIGURE 83-3  Lymph node stations in staging non-small-cell lung cancer. The International Association for the Study of Lung Cancer (IASLC) lymph node map, including the proposed grouping of lymph node stations into “zones” for the purposes of prognostic analyses. a., artery; Ao, aorta; Inf. pulm. ligt., inferior pulmonary ligament; n., nerve; PA, pulmonary artery; v., vein. ■ ■STAGING SYSTEM FOR NON-SMALL-CELL LUNG CANCER The tumor-node-metastasis (TNM) international staging system pro­ vides useful prognostic information and is used to stage all patients with NSCLC. The various T (tumor size), N (regional node involve­ ment), and M (presence or absence of distant metastasis) stages are combined to form different stage groups (Tables 83-5 and 83-6). The eighth edition of the TNM staging system went into effect in 2018. T1 tumors are divided into tumors ≤1 cm (T1a), >1 cm and ≤2 cm (T1b), and >2 cm and ≤3 cm (T1c). T2 tumors are those that are >3 cm but ≤5 cm, involve the visceral pleura or main bronchus, or are associ­ ated with atelectasis; T2a tumors are >3 cm and ≤4 cm, and T2b are >4 cm and ≤5 cm. T3 tumors are >5 cm and ≤7 cm. T3 tumors also include tumors with invasion into local structures such as the chest wall and diaphragm and with additional nodules in the same lobe. T4 tumors include tumors >7 cm or tumors of any size with invasion into mediastinum, heart, great vessels, trachea, esophagus, or spine or with multiple nodules in the ipsilateral lung. Lymph node staging depends on metastasis to ipsilateral pulmonary or hilar nodes (N1), mediastinal or subcarinal nodes (N2), or contralat­ eral mediastinal, hilar, or supraclavicular nodes (N3). Patients with metastasis may be classified as M1a (malignant pleural or pericardial effusion, pleural nodules, or nodules in the contralateral lung), M1b (single distant metastasis to a single organ; e.g., bone, liver, adrenal, or brain metastasis), or M1c (multiple metastases to a single organ or metastases to mul­ tiple organs). The ninth edition of the TNM classification is scheduled to be introduced sometime in 2024. 1 Highest mediastinal 2 Upper paratracheal 3 Prevascular and retrotracheal 4 Lower paratracheal (including azygos nodes) The effect of stage on survival is illus­ trated in Fig. 83-4. Approximately 15% of patients have localized disease that can be treated with curative attempt (surgery or radiotherapy), about a quarter have local or regional disease that may or may not be amenable to a curative attempt, and half have metastatic disease at the time of diagnosis. In 10%, the extent of disease is undefined. 5 Subaortic (A-P window) 6 Para-aortic (ascending aorta or phrenic) CHAPTER 83 7 Subcarinal ■ ■STAGING SYSTEM FOR SMALL-CELL LUNG CANCER In patients with SCLC, it is now recom­ mended that both the Veterans Admin­ istration system and the American Joint Committee on Cancer/International Union Against Cancer eighth edition system (TNM) be used to classify the tumor stage. The Veterans Administra­ tion system is a distinct two-stage system dividing patients into those with limited- or extensive-stage disease. Patients with limited-stage disease (LD) have cancer that is confined to the ipsilateral hemi­ thorax and can be encompassed within a tolerable radiation port. Thus, contra­ lateral supraclavicular nodes, recurrent laryngeal nerve involvement, and supe­ rior vena caval obstruction can all be part of LD. Patients with extensive-stage disease (ED) have overt metastatic dis­ ease by imaging or physical examination. Cardiac tamponade, malignant pleural effusion, and bilateral pulmonary paren­ chymal involvement generally qualify disease as ED, because the involved organs cannot be encompassed safely or effectively within a single radiation therapy port. Sixty to 70% of patients are diagnosed with ED at presentation. The TNM staging system is preferred in the rare SCLC patient presenting with what appears to be clinical stage I disease (see above). 8 Paraesophageal (below carina) Neoplasms of the Lung 9 Pulmonary ligament 10 Hilar 11 Interlobar 12 Lobar 13 Segmental 14 Subsegmental ■ ■PHYSIOLOGIC STAGING Patients with lung cancer often have other comorbid conditions related to smoking including cardiovascular disease and COPD. To improve their preoperative condition, correctable problems (e.g., anemia, electrolyte and fluid disorders, infections, cardiac disease, and arrhyth­ mias) should be addressed, appropriate chest physical therapy should be instituted, and patients should be encouraged to stop smoking. Patients with a forced expiratory volume in 1 s (FEV1) of >2 L or >80% of predicted may tolerate a pneumonectomy, and those with an FEV1 >1.5 L may have adequate reserve for a lobectomy. In patients with bor­ derline lung function but a resectable tumor, cardiopulmonary exercise testing could be performed as part of the physiologic evaluation. This test allows an estimate of the maximal oxygen consumption (VO2max). TABLE 83-5  TNM Staging System for Lung Cancer (Eighth Edition) Primary Tumor (T) T1 Tumor ≤3 cm diameter, surrounded by lung or visceral pleura, without invasion more proximal than lobar bronchus   T1mi Minimally invasive adenocarcinoma (pure lepidic pattern, <3 cm in greatest dimension and <5 mm invasion)—T1a (size ≤1 cm)— T1b (1 cm < size ≤ 2 cm)—T1c (2 cm < size ≤ 3 cm) T2 Tumor >3 cm but ≤5 cm, or tumor with any of the following features:     Involves main bronchus without carina, regardless of distance from carina     Invades visceral pleura     Associated with atelectasis or obstructive pneumonitis that extends to the hilar region but does not involve the entire lung   T2a Tumor >3 cm but ≤4 cm   T2b Tumor >4 cm but ≤5 cm T3 Tumor >5 cm but ≤7 cm or any of the following:   Directly invades any of the following: chest wall, pericardium, phrenic nerve   Separate (satellite) tumor nodules in the same lobe T4 Tumor >7 cm or any tumor with invasion of mediastinum, diaphragm, heart, great vessels, trachea, recurrent laryngeal nerve, esophagus, vertebral body, or carina, or with separate (satellite) tumor nodules in a different ipsilateral lobe PART 4 Oncology and Hematology Nodal Stage (N) N0 No regional lymph node metastases N1 Metastasis in ipsilateral peribronchial and/or ipsilateral hilar lymph nodes and intrapulmonary nodes, including involvement by direct extension N2 Metastasis in ipsilateral mediastinal and/or subcarinal lymph node(s) N3 Metastasis in contralateral mediastinal or hilar lymph node(s); ipsilateral/contralateral scalene/supraclavicular lymph node(s) Metastases (M) M0 No distant metastasis M1 Distant metastasis   M1a Separate tumor nodule(s) in a contralateral lobe; pleural/ pericardial nodule/malignant effusion   M1b Single extrathoracic metastasis, including single nonregional lymph node   M1c Multiple extrathoracic metastases in one or more organs Abbreviation: TNM, tumor-node-metastasis. A VO2max <15 mL/(kg.min) predicts for a higher risk of postoperative complications. Patients deemed unable to tolerate lobectomy or pneu­ monectomy from a pulmonary functional standpoint may be candi­ dates for more limited resections, such as wedge or anatomic segmental resection, although such procedures are associated with significantly TABLE 83-6  TNM Stage Groupings, Eighth Edition T/M Subcategory N0 N1 N2 N3 T1 T1a IA1 IIB IIIA IIIB   T1b IA2 IIB IIIA IIIB   T1c IA3 IIB IIIA IIIB T2 T2a IB IIB IIIA IIIB   T2b IIA IIB IIIA IIIB T3 T3 IIB IIIA IIIB IIIC T4 T4 IIIA IIIA IIIB IIIC M1 M1a IVA IVA IVA IVA   M1b IVA IVA IVA IVA   M1c IVB IVB IVB IVB higher rates of local recurrence and a trend toward decreased overall survival. All patients should be assessed for cardiovascular risk using American College of Cardiology and American Heart Association guidelines. A myocardial infarction within the past 3 months is a con­ traindication to thoracic surgery because 20% of patients will die of reinfarction. An infarction in the past 6 months is a relative contrain­ dication. Other major contraindications include uncontrolled arrhyth­ mias, an FEV1 of <1 L, CO2 retention (resting PCO2 >45 mmHg), DLCO <40%, and severe pulmonary hypertension. TREATMENT Non-Small-Cell Lung Cancer OCCULT AND STAGE 0 CARCINOMAS Patients with severe atypia on sputum cytology have an increased risk of developing lung cancer compared to those without atypia. In the uncommon circumstance where malignant cells are identified in a sputum or bronchial washing specimen but the chest imaging appears normal (TX tumor stage), the lesion must be localized. More than 90% of tumors can be localized by meticulous examina­ tion of the bronchial tree with a fiberoptic bronchoscope under general anesthesia and collection of a series of differential brushings and biopsies. Surgical resection following bronchoscopic localiza­ tion has been shown to improve survival compared to no treatment. Close follow-up of these patients is indicated because of the high incidence of second primary lung cancers (5% per patient per year). SOLITARY PULMONARY NODULE AND “GROUND-GLASS” OPACITIES A solitary pulmonary nodule is defined as an x-ray density com­ pletely surrounded by normal aerated lung with circumscribed margins, of any shape, usually 1–6 cm in greatest diameter. The approach to a patient with a solitary pulmonary nodule is based on an estimate of the probability of cancer, determined according to the patient’s smoking history, age, and characteristics on imag­ ing (Table 83-7). Prior CXRs and CT scans should be obtained if available for comparison. A PET scan may be useful if the lesion is >7–8 mm in diameter. If no diagnosis is apparent, Mayo investiga­ tors reported that clinical characteristics (age, cigarette smoking status, and prior cancer diagnosis) and three radiologic charac­ teristics (nodule diameter, spiculation, and upper lobe location) were independent predictors of malignancy. At present, only two radiographic criteria are thought to predict the benign nature of a solitary pulmonary nodule: lack of growth over a period >2 years and certain characteristic patterns of calcification. Calcification alone, however, does not exclude malignancy; a dense central nidus, multiple punctuate foci, and “bull’s eye” (granuloma) and “popcorn ball” (hamartoma) calcifications are highly suggestive of a benign lesion. In contrast, a relatively large lesion, lack of or asymmetric calcification, chest symptoms, associated atelectasis, pneumonitis, or growth of the lesion revealed by comparison with an old x-ray or CT scan or a positive PET scan may be suggestive of a malig­ nant process and warrant further attempts to establish a histologic diagnosis. An algorithm for assessing these lesions is shown in Fig. 83-5. Since the advent of screening CTs, small “ground-glass” opacities (GGOs) have often been observed, particularly as the increased sensitivity of CTs enables detection of smaller lesions. Many of these GGOs, when biopsied, are found to be atypical adenomatous hyper­ plasia (AAH), adenocarcinoma in situ (AIS), or minimally invasive adenocarcinoma (MIA). AAH is usually a nodule of <5 mm and is minimally hazy, also called nonsolid or ground glass (i.e., hazy slightly increased attenuation, no solid component, and preserva­ tion of bronchial and vascular margins). On thin-section CT, AIS is usually a nonsolid nodule and tends to be slightly more opaque than AAH. MIA is mainly solid, usually with a small (<5 mm) central solid component. However, overlap exists among the imag­ ing features of the preinvasive and minimally invasive lesions in 100% 80% 60% 40% 20% 0% Months FIGURE 83-4  Influence of non-small-cell lung cancer stage on survival. Overall survival by non-small-cell lung cancer stage, according to eighth edition groupings using entire database available for the eighth edition as of 2016. the lung adenocarcinoma spectrum. Lepidic adenocarcinomas are usually solid but may be nonsolid. Likewise, the small invasive adenocarcinomas also are usually solid but may exhibit a small nonsolid component. PREFACE TO MANAGEMENT OF LUNG CANCER The landscape of lung cancer management, spanning from screen­ ing and early detection to addressing early-stage, locally advanced, and distant disease, is undergoing continuous evolution. The dynamic nature of this evolution is best exemplified by the approval of 12 drugs in the United States only between 2022 and 2023. Within the confines of this single chapter, presenting the most current and comprehensive management recommendations proves challenging, if not impossible, due to the accelerated pace of the evolving treatment armamentarium. Therefore, it is recommended to consult the latest professional guidelines for the most up-to-date best practices (Table 83-8). MANAGEMENT OF STAGES I AND II NSCLC Surgical Resection of Stage I and II NSCLC  Surgical resection, ideally by an experienced thoracic surgeon, is the treatment of choice for patients with clinical stage I and II NSCLC who are able to tolerate the procedure. Operative mortality rates for patients resected by thoracic or cardiothoracic surgeons are lower compared to general surgeons. Moreover, survival rates are higher in patients who undergo resection in facilities with a high surgical volume compared to those performing fewer than 70 procedures per year, even though the higher-volume facilities often serve older and less socioeconomically advantaged populations. The improvement in survival is most evident in the immediate postoperative period. In TABLE 83-7  Assessment of Risk of Cancer in Patients with Solitary Pulmonary Nodules RISK VARIABLE LOW INTERMEDIATE HIGH Diameter (cm) <1.5 1.5–2.2 ≥2.3 Age (years) <45 45–60 >60 Smoking status Never smoker Current smoker (<20 cigarettes/d) Current smoker (>20 cigarettes/d) Smoking cessation status Quit ≥7 years ago or quit Quit <7 years ago Never quit Characteristics of nodule margins Smooth Scalloped Corona radiata or spiculated Source: From The New England Journal of Medicine. The Solitary Pulmonary Nodule. D Ost et al: 348:2535-2542. Copyright @ 2003 Massachusetts Medical Society. Reprinted with permission from Massachusetts Medical Society. Stage 24 months 60 months 77% 83% 92% 90% 94% 97% IA3 IA2 IA1 IA3 IA2 IA1 68% 87% IB IB IIA IIB IIIA IIIB 60% 79% IIA 53% 72% IIB 36% 55% IIIA IIIC IVA IVB 26% 44% IIIB 13% 24% IIIC 10% 23% IVA 0% 10% IVB CHAPTER 83 patients with stage I NSCLC, lobectomy is superior to wedge resec­ tion with respect to rates of local recurrence. There is also a trend toward improvement in overall survival. In patients with comor­ bidities, compromised pulmonary reserve, and small peripheral lesions, a limited resection, wedge resection, or segmentectomy (potentially by video-assisted thoracoscopic surgery) may be rea­ sonable surgical options. Pneumonectomy is reserved for patients with central tumors and should be performed only in patients with excellent pulmonary reserve. According to the Surveillance, Epi­ demiology, and End Results (SEER) data from 2022, patients with localized disease have a 5-year survival rate of 63%. Neoplasms of the Lung Accurate pathologic staging requires adequate segmental, hilar, and mediastinal lymph node sampling. Ideally, this includes a medi­ astinal lymph node dissection. Although there are no evidence-based guidelines mandating the number of lymph nodes to be removed at surgery for adequate staging, the International Association for the Study of Lung Cancer staging manual states that suitable nodal staging generally includes sampling/dissection of lymph nodes from stations 2R, 4R, 7, 10R and 11R on the right side, and from stations 5, 6, 7, 10L, and 11L on the left side. Hilar lymph nodes are typically resected and sent for pathologic review, although it is helpful to specifically dissect and label level 10 lymph nodes when possible. On the left side, level 2 and sometimes level 4 lymph nodes are generally obscured by the aorta. Although the therapeutic benefit of nodal dissection versus nodal sampling is controversial, a pooled analysis of three trials involving patients with stages I to IIIA NSCLC demonstrated a superior 4-year survival in patients undergoing resection and a complete mediastinal lymph node dis­ section compared with lymph node sampling. Moreover, complete mediastinal lymphadenectomy added little morbidity to a pulmo­ nary resection for lung cancer when carried out by an experienced thoracic surgeon. Radiation Therapy in Stages I and II NSCLC  There is currently no role for postoperative radiation therapy in patients following resection of stage I or II NSCLC with negative margins. However, patients with stage I and II disease who either decline or are not suitable candidates for surgery should be considered for radiation therapy with curative intent. Stereotactic body radiation therapy (SBRT) is a technique used to treat patients with isolated pulmo­ nary nodules (≤5 cm) who are not candidates for or refuse surgical resection. Treatment is typically administered in three to five frac­ tions delivered over 1–2 weeks. In uncontrolled studies, disease control rates are >90%, and 5-year survival rates of up to 60% have been reported with SBRT. By comparison, survival rates typically range from 13 to 39% in patients with stage I or II NSCLC treated with standard external-beam radiotherapy. Cryoablation is another New nodule identified on standard CT scanning Benign calcification pattern on CT or stability for 2 yr on archival films Risk factors for surgery • Predicted postoperative FEV1 <0.8 L • VO2 max <10–15 mL/kg/min . Does probability of cancer warrant surgery, given the surgical risk? PART 4 Oncology and Hematology Moderate probability of cancer (10–60%) Low probability of cancer (<10%) Additional testing • PET if nodule ≥1 cm in diameter • Contrast-enhanced CT, depending on institutional experties • Transthoracic fine-needle aspiration biopsy if nodule is peripherally located • Bronchoscopy if air-bronchus sign present Negative tests Positive tests Video-assisted thoracoscopic surgery; examination of a frozen section, followed by lobectomy if nodule is malignant Serial high-resolution CT at 3, 6, 9, 12, 18, and 24 mo FIGURE 83-5  Approach to the solitary pulmonary nodule. FEV1, forced expiratory volume in 1 s; PET, positron emission tomography. technique occasionally used to treat small, isolated tumors (i.e., ≤3 cm). However, very little data exist on long-term outcomes with this technique. Systemic Therapy in Stages I and II NSCLC  For nearly two decades, chemotherapy has historically served as the cornerstone of adjuvant systemic therapy for patients with early-stage resected disease. The landmark meta-analysis of cisplatin-based adjuvant chemotherapy trials in patients with resected stages I to IIIA NSCLC (the Lung Adjuvant Cisplatin Evaluation [LACE] Study) published in 2008 demonstrated a 5.4% improvement in 5-year survival for cisplatin-based chemotherapy compared to surgery alone, thus becoming the standard-of-care adjuvant therapy recommenda­ tion. The survival benefit was seemingly confined to patients with stage II or III disease (Table 83-9). By contrast, survival was actually TABLE 83-8  Select References to Professional Guidelines, in Alphabetical Order American Society of Clinical Oncology (ASCO), Thoracic Cancer 2. European Society for Medical Oncology (ESMO) Clinical Practice Guidelines: Lung and Chest Tumors 3. International Association for the Study of Lung Cancer (IASLC), Guidelines 4. National Comprehensive Cancer Network (NCCN), Non-Small-Cell Lung Cancer Guidelines Yes No further testing No Yes No worsened in stage IA patients with the application of adjuvant therapy. In stage IB, there was a modest improvement in survival of question­ able clinical significance, particularly for patients with a resected lesion ≥4 cm. Adjuvant chemotherapy was also detrimental in patients with poor performance status (Eastern Cooperative Oncology Group [ECOG] performance status = 2). These data suggest that adjuvant chemotherapy is best applied in patients with resected stage II or III NSCLC, with potential benefit for a select group of stage IB patients. As with any treatment recommendation, the risks and benefits of adjuvant chemotherapy should be considered on an individual patient basis. If a decision is made to proceed with adjuvant che­ motherapy, in general, treatment should be initiated 6–12 weeks after surgery, assuming the patient has fully recovered, and should be administered for no more than four cycles. Although cisplatinbased chemotherapy is the preferred treatment regimen, carbo­ platin can be substituted for cisplatin in patients who are unlikely to tolerate cisplatin for reasons such as reduced renal function, presence of neuropathy, or hearing impairment. A large coop­ erative group trial compared cisplatin-based chemotherapy with vinorelbine, pemetrexed, gemcitabine, or docetaxel with or without antiangiogenic therapy. The study found similar efficacy across all treatments. Therefore, no specific chemotherapy regimen is consid­ ered superior in this setting, and treatment selection may be based on cost and patient comorbidities. From 2020 onward, systemic therapies, initially employed in the metastatic setting—such as targeted therapy and TABLE 83-9  Adjuvant Chemotherapy Trials in Non-Small-Cell Lung Cancer 5-YEAR SURVIVAL (%) P NO. OF PATIENTS TRIAL STAGE TREATMENT IALT I–III Cisplatin-based Control 44.5 40.4 BR10 IB–II Cisplatin + vinorelbine Control ANITA IB–IIIA Cisplatin + vinorelbine Control ALPI I–III MVP Control BLT I–III Cisplatin-based Control CALGB IB Carboplatin + paclitaxel ECOG1505 IB > 4c – IIIA Cisplatin-based Cisplatin-based + bevacizumab NR NR Abbreviations: ALPI, Adjuvant Lung Cancer Project Italy; ANITA, Adjuvant Navelbine International Trialist Association; BLT, Big Lung Trial; CALGB, Cancer and Lung Cancer Group B; ECOG, Eastern Cooperative Oncology Group; IALT, International Adjuvant Lung Cancer Trial; MVP, mitomycin, vindesine, and cisplatin; NR, not reported. immunotherapy—have been incorporated into the curative approach for patients with NSCLC (Table 83-10). Osimertinib, an EGFR tyrosine kinase inhibitor (TKI), dem­ onstrated improved disease-free survival in the adjuvant setting TABLE 83-10  Select Therapeutic Strategies Incorporating Immunotherapy or Targeted Therapy In Early-Stage, Resectable Non-Small-Cell Lung Cancer (NSCLC) STAGE AND DISEASE CHARACTERISTICS REGIMEN APPROVAL ENDPOINT TRIAL Neoadjuvant CheckMate IB–IIIA Irrespective of PD-L1 Nivolumab + chemotherapy × 3 cycles EFS HR 0.63, p = .005 Perioperative KEYNOTE-671 II–IIIB (N2) Irrespective of PD-L1 Pembrolizumab + chemotherapy × 4 cycles → surgery → pembrolizumab × ~9 months EFS HR 0.58, p < .00001 OS HR 0.72, p = .00517 Adjuvant IMPower010 II–IIIA PD-L1 positive (≥1%) Adjuvant chemotherapy → atezolizumab × 1 year DFS HR 0.66, p = .004 KEYNOTE 091/ PEARLS IB–IIIA Irrespective of PD-L1 Adjuvant chemotherapy → pembrolizumab × 1 year DFS HR 0.73 ADAURA IB–IIIA EGFR exon 19 deletions or exon 21 L858R Osimertinib × 3 years (irrespective of adjuvant chemotherapy) DFS HR 0.20, p < .0001 OS HR 0.49, p < .001 ALINA IB-IIIA ALK fusion positive Alectinib × 2 years DFS HR 0.24; P<0.001, 95% CI, 0.13 to 0.43 Abbreviations: DFS, disease-free survival; EFS, event-free survival; EGFR, epidermal growth factor receptor; HR, hazard ratio; OS, overall survival; PD-L1, programmed death ligand 1. for patients with EGFR mutation (exon 19 deletion or L858R)– positive NSCLC treated for 3 years with or without chemotherapy; improved overall survival benefit with adjuvant osimertinib was also reported. Regulatory authorities including the U.S. FDA, the European Commission, and China’s National Medical Products Administration have granted approval for adjuvant osimertinib in resected, stages IB–IIIA EGFR-mutant NSCLC. Furthermore, the exploration of additional targeted therapies in the adjuvant setting is ongoing, as seen for example in the phase 3 ALINA trial investi­ gating oral alectinib for patients with ALK fusion oncogene–posi­ tive NSCLC. This highlights a dynamic landscape in the pursuit of enhanced treatment outcomes for patients with early-stage NSCLC. < .03 .03 .017 Approved adjuvant immunotherapy regimens, using either atezoli­ zumab or pembrolizumab, involve approximately 1 year of treat­ ment following adjuvant chemotherapy. This treatment approach is supported by the disease-free survival benefit observed in the IMpower010 and KEYNOTE-091 trials. Notably, the association between treatment benefit and the level of PD-L1 expression varied. .49 .90 Neoadjuvant chemotherapy, which is the application of chemo­ therapy administered before an attempted surgical resection, has been advocated by some experts on the assumption that such an approach will more effectively extinguish occult micrometastases compared to postoperative chemotherapy. In addition, there is thought that preoperative chemotherapy might render an inoper­ able lesion resectable. A meta-analysis of 15 randomized controlled trials involving >2300 patients with stage I–III NSCLC suggested there may be a modest 5-year survival benefit (i.e., ∼5%) that is virtually identical to the survival benefit achieved with postop­ erative chemotherapy. Accordingly, neoadjuvant therapy may prove useful in selected cases (see below). A decision to use neoadjuvant chemotherapy should always be made in consultation with an experienced surgeon. Neoadjuvant immunotherapy combined with chemotherapy has gained approval for patients with stage IB–IIIA, resectable NSCLC, with neoadjuvant nivolumab plus chemotherapy for three cycles resulting in a pathologic complete response rate of 24% and statistically significant event-free survival benefit over chemotherapy alone (hazard ratio [HR] 0.63; p = .005) in the CheckMate 816 trial. .10 .90 CHAPTER 83 Neoplasms of the Lung Various perioperative (i.e., before and after surgical resection) treatment strategies have been explored for patients with resect­ able NSCLC. This involves a neoadjuvant chemoimmunotherapy approach followed by adjuvant immunotherapy. A perioperative treatment approach with pembrolizumab in combination with chemotherapy has been approved for patients with stages II–IIIB, resectable NSCLC. This approval is based on the results of the KEYNOTE-671 phase 3 trial that demonstrated a significant overall survival and event-free survival benefit over preoperative chemo­ therapy alone. All patients with resected NSCLC are at high risk of developing a second primary lung cancer or recurrence, most of which occur within 18–24 months of surgery. Thus, these patients should be followed with regular physical examinations and periodic imaging studies. Given the results of the NLST, periodic CT scans appear to be the most appropriate screening modality. Professional guide­ lines, such as those from the National Comprehensive Cancer Net­ work (NCCN), recommend a chest CT scan every 3–6 months for the first 3 years after surgery, then every 6 months for 2 years, and then annually to monitor for recurrence. MANAGEMENT OF STAGE III NSCLC Management of patients with stage III NSCLC usually requires a combined-modality approach. Patients with stage IIIA disease com­ monly are stratified into those with “nonbulky” or “bulky” medias­ tinal lymph node (N2) disease. Although the definition of “bulky” N2 disease varies somewhat in the literature, the usual criteria include the size of a dominant lymph node (i.e., >2–3 cm in shortaxis diameter as measured by CT), groupings of multiple smaller lymph nodes, evidence of extracapsular nodal involvement, or involvement of more than two lymph node stations. The distinction between nonbulky and bulky stage IIIA disease is mainly used to select potential candidates for upfront surgical resection or for resection after neoadjuvant therapy. Many aspects of therapy of patients with stage III NSCLC remain controversial, and the opti­ mal treatment strategy has not been clearly defined. Furthermore, because stage III disease is highly heterogeneous, no single treat­ ment approach can be recommended for all patients. Key factors guiding treatment choices include the particular combination of tumor (T) and nodal (N) disease, the ability to achieve a complete surgical resection if indicated, and the patient’s overall physi­ cal condition and preferences. For example, in carefully selected patients with limited stage IIIA disease where involved mediastinal lymph nodes can be completed resected, initial surgery followed by postoperative chemotherapy (with or without radiation therapy) may be indicated. By contrast, for patients with clinically evident bulky mediastinal lymph node involvement, the standard approach to treatment is concurrent chemoradiotherapy followed by a year of consolidation immunotherapy with durvalumab. Absent and Nonbulky Mediastinal (N2, N3) Lymph Node Disease  For the subset of stage IIIA patients initially thought to have clinical stage I or II disease (i.e., pathologic involvement of mediastinal [N2] lymph nodes is not detected preoperatively), surgical resection is often the treatment of choice. This is followed by adjuvant che­ motherapy in patients with microscopic lymph node involvement in a resection specimen. Postoperative radiation therapy (PORT) may also have a select role for those with close or positive surgical margins. Patients with tumors exceeding 7 cm in size or involving the chest wall or proximal airways within 2 cm of the carina with hilar lymph node involvement (but not N2 disease) are classified as having T3N1 stage IIIA disease. They too are best managed with surgical resection, if technically feasible, followed by adjuvant chemotherapy if completely resected. Patients with T3N0 or T3N1 disease due to the presence of satellite nodules within the same lobe as the primary tumor are also candidates for surgery, as are patients with ipsilateral nodules in another lobe and negative mediastinal nodes (IIIA, T4N0 or T4N1). Although data regarding adjuvant chemotherapy in the latter subsets of patients are limited, it is often recommended. PART 4 Oncology and Hematology Patients with T4N0-1 may have involvement of the carina, supe­ rior vena cava, or a vertebral body and yet still be candidates for sur­ gical resection in selected circumstances. The decision to proceed with an attempted resection must be made in consultation with an experienced thoracic surgeon often in association with a vascular or cardiac surgeon and an orthopedic surgeon depending on tumor location. However, if an incomplete resection is inevitable or if there is evidence of N2 involvement (stage IIIB), surgery for T4 disease is contraindicated. Most T4 lesions are best treated with concurrent chemoradiotherapy followed by durvalumab. The role of PORT in patients with completely resected stage III NSCLC is controversial. To a large extent, the use of PORT has historically been dictated by the presence or absence of N2 involve­ ment and, to a lesser degree, by the biases of the treating physician. Using the SEER database, a meta-analysis of PORT identified a significant increase in survival in patients with N2 disease but not in patients with N0 or N1 disease. An earlier analysis by the PORT Meta-analysis Trialist Group using an older database produced similar results. However, two large, randomized phase 3 trials (PORT-C and Lung ART) have shown that PORT should not be routinely recommended as standard of care for patients given no improvement in disease-free survival and increased risk for cardio­ pulmonary toxicity. Known Mediastinal (N2, N3) Lymph Node Disease  When patho­ logic involvement of mediastinal lymph nodes is documented preoperatively, a combined-modality approach is recommended assuming the patient is a candidate for treatment with curative intent. These patients are at high risk for both local and distant recurrence if managed with resection alone. For patients with stage III disease who are not candidates for surgical resection, concurrent chemoradiotherapy is most commonly used as the initial treatment followed by durvalumab. Concurrent chemoradiotherapy has been shown to produce superior survival compared to sequential chemo­ radiotherapy; however, it also is associated with greater host toxici­ ties (including fatigue, esophagitis, and neutropenia). Therefore, for patients with a good performance status, concurrent chemoradio­ therapy is the preferred treatment approach, whereas sequential chemoradiotherapy may be more appropriate for patients with a performance status that is not as good. For patients who are not candidates for a combined-modality treatment approach, typically due to a poor performance status or a comorbidity that makes chemotherapy untenable, radiotherapy alone may provide a modest survival benefit in addition to symptom palliation. For patients with potentially resectable N2 disease, it remains uncertain whether surgery after neoadjuvant chemoradiotherapy improves survival. In an NCI-sponsored Intergroup randomized trial comparing concurrent chemoradiotherapy alone to concur­ rent chemoradiotherapy followed by attempted surgical resection, no survival benefit was observed in the trimodality arm compared to the bimodality therapy. In fact, patients subjected to a pneumo­ nectomy had a worse survival outcome. By contrast, those treated with a lobectomy appeared to have a survival advantage based on a retrospective subset analysis. Thus, in carefully selected, otherwise healthy patients with nonbulky mediastinal lymph node involve­ ment, surgery may be a reasonable option if the primary tumor can be fully resected with a lobectomy. This is not the case if a pneumo­ nectomy is required to achieve complete resection. Advancements in neoadjuvant therapy, particularly in the realm of combination chemoimmunotherapy, have led to interest in exploring the benefits of such therapy for patients with N2 disease. The NADIM II phase 2 trial is an illustrative example that exclu­ sively enrolled patients with stage IIIA–IIIB disease per American Joint Committee on Cancer eighth edition criteria; notably, twothirds of these patients had N2 disease, including cases of multi­ station N2 disease. The trial demonstrated a pathologic complete response rate (pCR) of 36–42% with chemoimmunotherapy for patients with N2 disease, compared to 0–10% pCR rate for those who received neoadjuvant chemotherapy alone. Additionally, the study demonstrated the safety of a neoadjuvant chemoimmuno­ therapy approach in patients with N2 disease, without compromis­ ing the feasibility of surgical outcomes. Further investigation is warranted to better define the role of novel neoadjuvant therapeutic strategies for patients with N2 disease. Superior Sulcus Tumors (Pancoast Tumors)  Superior sulcus tumors represent a distinctive subset of stage III disease. These tumors arise in the apex of the lung and may invade the second and third ribs, the brachial plexus, the subclavian vessels, the stel­ late ganglion, and adjacent vertebral bodies. They also may be associated with Pancoast syndrome, characterized by pain that may arise in the shoulder or chest wall or radiate to the neck. Pain characteristically radiates to the ulnar surface of the hand. Horner’s syndrome (enophthalmos, ptosis, miosis, and anhidrosis) due to invasion of the paravertebral sympathetic chain may be present as well. Patients with these tumors should undergo the same staging procedures as all patients with stage II and III NSCLC. Neoadjuvant chemotherapy or combined chemoradiotherapy followed by sur­ gery is reserved for those without N2 involvement. This approach yields excellent survival outcomes (>50% 5-year survival in patients with an R0 resection). Patients with N2 disease are less likely to benefit from surgery and can be managed with chemoradiotherapy followed by durvalumab. Patients presenting with metastatic dis­ ease can be treated with radiation therapy (with or without chemo­ therapy) for symptom palliation. SURGICAL MANAGEMENT OF NSCLC Traditionally, in patients with NSCLC, the following have been relative contraindications to potential curative resection: extratho­ racic metastases, superior vena cava syndrome, vocal cord and, in most cases, phrenic nerve paralysis, malignant pleural effusion, cardiac tamponade, tumor within 2 cm of the carina (poten­ tially curable with combined chemoradiotherapy), metastasis to the contralateral lung, metastases to supraclavicular lymph nodes, contralateral mediastinal node metastases (potentially curable with combined chemoradiotherapy), and involvement of the main pul­ monary artery. In situations where it will make a difference in treatment, abnormal scan findings should be further investigated and require tissue confirmation of malignancy so that patients are not precluded from having potentially curative therapy. The role of surgical management of NSCLC continues to evolve, given emerg­ ing neoadjuvant/perioperative treatment strategies, and warrants multidisciplinary discussion. MANAGEMENT OF METASTATIC NSCLC Approximately 40% of NSCLC patients present with advanced, stage IV disease at the time of diagnosis. In addition, a significant number of patients who first presented with early-stage NSCLC will eventually relapse with distant disease. Patients who have recurrent disease have a better prognosis than those presenting with meta­ static disease at the time of diagnosis. Standard medical manage­ ment, the appropriate use of pain medications, and the pertinent use of radiotherapy and systemic therapy—which may consist of targeted therapy, immunotherapy, and/or traditional cytotoxic che­ motherapy depending on the specific diagnosis as well as PD-L1 TPS and molecular subtype—form the cornerstone of management. Systemic therapy palliates symptoms, improves quality of life, and improves survival in patients with metastatic NSCLC, particularly in patients with good performance status. Of note, the early applica­ tion of palliative care in conjunction with chemotherapy in patients with advanced NSCLC is associated with both improved survival and quality of life. Targeted Therapies for Select Molecular Cohorts of NSCLC  For a cohort of NSCLC patients, the presence of an oncogenic driver mutation allows the use of oral therapies with significant antitumor activity and improved survival compared to cytotoxic chemo­ therapy. These driver mutations occur in genes encoding signaling proteins that, when aberrant, promote the uncontrolled growth and metastasis of tumor cells. Importantly, driver mutations can serve as Achilles’ heels for tumors, if their gene products can be targeted therapeutically with small-molecule inhibitors. All patients with advanced NSCLC should ideally undergo comprehensive molecular testing (i.e., multigene testing encompassing at least all biomarkers for which there are approved biomarker-matched therapies, includ­ ing less common driver mutations) with broad panel-based testing techniques such as NGS as opposed to conventional, single-gene targeted testing strategies. Point mutations, insertions/deletions, chromosomal rearrangements (sometimes called “fusions”), and copy number variants have been reported in a number of genes including ALK, BRAF, EGFR, ERRB2, KRAS, MET, NRAS, NRG1, NTRK, PIK3ca, RET, and ROS1, with varying levels of clinical evidence. As our treatment armamentarium expands, knowledge of these mutations is critical for selection of appropriate therapy. EGFR mutations have been detected in 10–15% of North American patients diagnosed with NSCLC. EGFR mutations are typically (but not exclusively) associated with younger age, light (<10 pack-year) and nonsmokers, and adenocarcinoma histology. Approximately 90% of these mutations are exon 19 deletions or exon 21 L858R point mutations within the EGFR tyrosine kinase domain, resulting in hyperactivation of both EGFR kinase activity and downstream signaling. Lung tumors that harbor activating mutations within the EGFR kinase domain display high sensitivity to small-molecule EGFR TKIs. Osimertinib, erlotinib, gefitinib, afatinib, and dacomi­ tinib are FDA-approved oral small-molecule TKIs that inhibit EGFR. Several large, international, phase 3 studies have demon­ strated improved response rates and progression-free survival in patients with EGFR mutation–positive NSCLC treated with an EGFR TKI as compared with standard first-line chemotherapy regi­ mens (Table 83-11). Osimertinib was shown in a randomized phase 3 trial to have superior progression-free and overall survival in TABLE 83-11  Phase 3 Trials of EGFR TKIs in EGFR-Positive Non-Small-Cell Lung Cancer NO. OF PATIENTS ORR (%) PFS (MONTHS) TRIAL THERAPY IPASS CbP 6.3   Gefitinib 9.3 EURTAC CG 5.2   Erlotinib 9.7 OPTIMAL CG 4.6   Erlotinib 13.1 NEJOO2 CG 5.4   Gefitinib 10.8 WJTOG3405 CD 6.3   Gefitinib 9.2 LUX LUNG 3 CP 6.9   Afatinib 11.1 LUX LUNG 6 CG 5.6   Afatinib 11.0 LUX LUNG 7 Erlotinib 10.9 CHAPTER 83   Afatinib 11.0 ARCHER 1050 Gefitinib 9.2   Dacomitinib 14.7 FLAURA Erlotinib or gefitinib 8.5   Osimertinib 17.2 Neoplasms of the Lung FLAURA2 Osimertinib/ chemotherapy 25.5   Osimertinib 16.7 MARIPOSA Amivantamab/ lazertinib 23.7   Osimertinib 16.6 Abbreviations: CbP, carboplatin and paclitaxel; CD, cisplatin and docetaxel; CG, cisplatin and gemcitabine; CP, cisplatin and paclitaxel; EGFR, epidermal growth factor receptor; ORR, overall response rate; PFS, progression-free survival; TKI, tyrosine kinase inhibitor. patients with EGFR-mutant NSCLC compared to earlier-generation EGFR TKIs (erlotinib or gefitinib) and to chemotherapy. Emerging combination strategies in the first-line setting, such as combining osimertinib with platinum-based chemotherapy, are also gaining traction. EGFR exon 20 insertion mutations are the third most com­ mon EGFR mutation. The anti-EGFR therapies described above are not approved for use in the context of tumors that harbor EGFR exon 20 insertion mutations. The current standard of care for EGFR exon 20–mutated lung cancer is a combination of platinum-based chemotherapy with amivantamab, which is an EGFR-MET bispe­ cific antibody. HER2/ERBB2 mutations have also been detected in ~3% of nonsquamous NSCLC. HER2, like EGFR, is a member of the ERBB family of receptor tyrosine kinases. The most common HER2 muta­ tions in lung cancer encompass insertion variants within exon 20, which is part of the tyrosine kinase domain (so-called “exon 20 insertions”). The anti-HER2 monoclonal antibody-drug conjugate, trastuzumab deruxtecan, is approved for patients with previously treated, metastatic NSCLC harboring a mutation in HER2/ERRB2, with an objective response rate of ~50% and median progressionfree survival of ~8 months. Chromosomal Rearrangements in NSCLC  Chromosomal rear­ rangements are found in ~10% of patients with NSCLC. Typically, although not exclusively, chromosomal rearrangements are associ­ ated with younger age, no smoking history, and adenocarcinoma histology. However, given the potential therapeutic impact, it is strongly recommended that all patients are tested. Given that the resultant fusion proteins include the entire tyrosine kinase domain, the most effective therapeutic strategy at this time is with TKIs. TABLE 83-12  Results of Phase 3 Trials Comparing First-Line ALK Inhibitors in ALK-Positive NSCLC NO. OF PATIENTS ORR (%) MEDIAN PFS TRIAL THERAPY Profile 1014 Crizotinib 10.9 Platinumchemotherapy 7.0 ALEX Alectinib 82.9 34.8 Crizotinib 75.5 10.9 ALTA1L Brigatinib 67% at 24 months Crizotinib 43% at 11 months eXalt3 Ensartinib Crizotinib 25.8 12.7 CROWN Lorlatinib Crizotinib 64% at 60 months 9.1 Abbreviations: NSCLC, non-small-cell lung cancer; ORR, overall response rate; PFS, progression-free survival. In NSCLC, chromosomal rearrangements involving the ana­ plastic lymphoma kinase (ALK) gene on chromosome 2 have been found in ∼3–7% of patients with NSCLC. ALK rearrangements lead to hyperactivation of the ALK tyrosine kinase domain. Crizotinib is a first-generation ALK TKI, whereas alectinib, brigatinib, and ceritinib are second-generation ALK TKIs approved as first-line treatment options for patients with lung tumors harboring ALK rearrangements. Both alectinib and brigatinib have been found to have superior progression-free survival to crizotinib. Lorlatinib, a third-generation ALK TKI, is also approved for patients in the firstline setting and for patients who progress on a second-generation ALK TKIs (Table 83-12). Unique adverse events of lorlatinib may include hyperlipidemia, weight gain, and cognitive effects. ALK testing may be performed via fluorescence in situ hybridization (FISH), immunohistochemistry (IHC), or NGS. PART 4 Oncology and Hematology ROS1 fusions, detected by FISH or NGS, have been identified in ∼1–2% of patients with NSCLC. Crizotinib, which inhibits both ROS1 and MET kinases, and the ROS1/TRK inhibitors entrectinib and repotrectinib have been FDA approved for patients whose tumors harbor a ROS1 fusion. Entrectinib and repotrectinib offer improved blood-brain barrier penetration. RET alterations typically occur as chromosomal rearrange­ ments resulting in constitutive TKI activation. RET rearrange­ ments may be detected by either FISH or NGS in ~1% of NSCLC patients. Analogous to capmatinib, pralsetinib and selperca­ tinib have demonstrated an excellent response rate; as many as Obtain tissue EGFR Exon 19 deletion and EGFR L858R Determine driver EGFR Exon 20 Insertion ERBB2 (HER2) mutation RET fusion ALK fusion ROS1 fusion KRAS G12C Alectinib Brigatinib Ceritinib Crizotinib Lorlatinib Famtrastuzumab deruxtecan-nxki, Ado-trastuzumab emtansine Afatinib, Dacomitinib, Erlotinib, Erlotinib + ramucirumab, Erlotinib + bevacizumab, Gefitinib, Osimertinib, Osimertinib + chemotherapy Amivantamab + Carboplatin/ Pemetrexed (nonsquamous) Adagrasib*, Sotorasib* Targeted therapy Treatment Options * Approved as second-line therapy only. FIGURE 83-6  United States-centric approach to targeted therapy in non-small-cell lung cancer (NSCLC) based on drug approvals. Acknowledging regional variances in approvals. Drugs are listed alphabetically, not by author preference. Current as of June 2024. 78–85% of treatment-naïve NSCLC patients with RET alterations responded. NTRK fusions occur in members of the NTRK gene family (NTRK1, NTRK2, NTRK3) and result in constitutive protein kinase activation. NTRK fusions are rare, occurring in <1% of patients with NSCLC. Entrectinib and larotrectinib have demonstrated durable antitumor efficacy and are currently approved for NTRK-positive NSCLC. Targeting the Mitogen-Activated Protein Kinase (MAPK) Pathway in NSCLC  The MAPK pathway may be dysregulated in a subset of patients with NSCLC. For example, mutations within the KRAS GTPase are found in ∼25% of lung adenocarcinomas, with muta­ tions in KRAS G12C occurring in ~14% of adenocarcinomas. Agents targeting KRAS G12C such as adagrasib and sotorasib are now approved, with objective response rates of ~42 and ~37%, respectively. Defining mechanisms of acquired resistance to smallmolecule inhibitors is a high research priority. Oncogenic mutations in BRAF have been observed in ~2% of patients with NSCLC and, similar to KRAS, may serve as a key oncogene in the MAP kinase pathway. BRAF mutations may occur in both squamous and nonsquamous NSCLC and with an equal prevalence in patients with a history of smoking. This mutation is typically most targetable when it occurs at the 600th amino acid valine (V600). Combined inhibition with a BRAF and MEK inhibi­ tor, dabrafenib plus trametinib or encorafenib with binimetinib, is a first-line or later therapeutic option in patients with BRAF V600–mutant NSCLC and appears to be superior to BRAF or MEK inhibition alone. MET exon 14 skipping mutations have also been identified in ~3–5% of patients with NSCLC. Notably, MET exon 14 skipping mutations may occur in both squamous and nonsquamous NSCLC patients and those with a history of smoking. Pharmacologic inhibition of the overactive MET pathway with FDA-approved capmatinib or tepotinib resulted in response rates >70%, particu­ larly in treatment-naïve NSCLC patients. A unique and challenging potential adverse event of oral MET inhibition with capmatinib and tepotinib is peripheral edema. All NCCN-supported targetable oncogenic driver mutations and potential therapeutic options are summarized in Fig. 83-6. Immunotherapy  Immune checkpoint inhibitors have significantly improved survival for a group of patients with locally advanced and metastatic NSCLC. These agents are used primarily in patients whose tumors do not express a targetable genetic lesion (Fig. 83-7). Immune checkpoint inhibitors work by blocking interactions between T cells and antigen-presenting cells (APCs) or tumor cells that lead to T-cell inactivation. By inhibiting this interaction, the immune system is effectively upregulated and T cells become Core biopsy to prove metastatic disease Atypical EGFR mutations: G719X, L861Q, and S768I BRAF V600E mutation MET exon 14 skipping mutation NTRK 1/2/3 Fusion Crizotinib, Entrectinib, Repotrectinib, (Ceritinib), (Lorlatinib) Dabrafenib/ Trametinib, Encorafenib/ Binimetinib, Vemurafenib Capmatinib, Crizotinib, Tepotinib Entrectinib Larotrectinib Pralsetinib, Selpercatinib Afatinib Obtain tissue Determine histology Squamous Determine PD-L1 status PD-L1 ≥50% PD-L1 ≥1% Anti-PD-1/PD-L1 monotherapy plus histologyspecific chemotherapy Anti-PD-1/PD-L1 monotherapy Treatment options Anti-PD-1/PD-L1 monotherapy plus histology-specific chemotherapy Anti-PD-1 plus Anti-CTLA-4 therapy Anti-PD-1 plus Anti-CTLA-4 therapy plus histologyspecific chemotherapy FIGURE 83-7  Approach to first-line therapy in a patient with stage IV, driver mutation–negative non-small-cell lung cancer (NSCLC). activated against tumor cells. Several randomized studies have demonstrated superior overall survival in patients treated with pembrolizumab or atezolizumab monotherapy or nivolumab plus ipilimumab combination immunotherapy compared to chemo­ therapy in patients with metastatic NSCLC with PD-L1 expression in ≥50% of tumor cells (KEYNOTE-024, IMPOWER 110) and ≥1% of tumor cells (KEYNOTE-042, CheckMate 227) (Table 83-13). The evidence supporting the use of single-agent immunotherapy in patients with tumor PD-L1 <50% remains unclear; current recom­ mendations suggest the use of chemotherapy plus immunotherapy or immunotherapy combinations as the first-line treatment strategy in patients with metastatic NSCLC with tumor PD-L1 <50%. As discussed below, specific regimens vary by tumor histology (adeno­ carcinoma vs squamous cell carcinoma). Although PD-L1 has been identified as a biomarker that can predict response to immune checkpoint inhibitors, responses are observed in patients who do not appear to express the biomarker, and not all PD-L1-positive patients respond to checkpoint inhibition. Importantly patients with driver mutations such as EGFR and ALK appear to derive greater benefit from targeted therapy than immunotherapy and should be treated with a TKI, even in the presence of high PD-L1 expression. Further evaluation of these agents in the neoadjuvant and perioperative settings and combined with chemoradiotherapy is ongoing. Cytotoxic Chemotherapy for Metastatic or Recurrent NSCLC  Cytotoxic chemotherapy is typically used in combination with immunotherapy as the initial treatment in patients with metastatic or recurrent NSCLC only when there is no contraindication to immunotherapy. Selected chemotherapy agents perform quite dif­ ferently in squamous carcinomas versus adenocarcinomas. Patients with nonsquamous NSCLC have an improved survival when Core biospy of most distant site of disease to prove metastatic disease Nonsquamous and no actionable mutations PD-L1 ≥1% PD-L1 <50% and EGFR, ALK, and ROS1 negative PD-L1 <1% PD-L1 ≥50% Anti-PD-1/PD-L1 monotherapy plus histologyspecific chemotherapy Anti-PD-1/PD-L1 monotherapy plus histologyspecific chemotherapy Anti-PD-1/PD-L1 monotherapy plus histologyspecific chemotherapy Anti-PD-1/PD-L1 monotherapy Anti-PD-1/PD-L1 monotherapy plus histology-specific chemotherapy CHAPTER 83 Anti-PD-1 plus Anti-CTLA-4 therapy plus histologyspecific chemotherapy Anti-PD-1 plus Anti-CTLA-4 therapy plus histologyspecific chemotherapy Anti-PD-1 plus Anti-CTLA-4 therapy Anti-PD-1 plus Anti-CTLA-4 therapy plus histologyspecific chemotherapy Neoplasms of the Lung treated with cisplatin and pemetrexed compared to cisplatin and gemcitabine. By contrast, patients with squamous carcinoma have an improved survival when treated with cisplatin and gemcitabine. This survival difference is thought to be related to the differential expression between tumor types of thymidylate synthase (TS). Squamous cancers have a much higher expression of TS compared to adenocarcinomas, accounting for their lower responsiveness to pemetrexed. By contrast, the activity of gemcitabine is not impacted by the levels of TS. Second-Line Therapy and Beyond  Second-line therapy for advanced NSCLC relies on docetaxel; it improves survival com­ pared to supportive care alone. Ramucirumab is a recombinant human IgG1 monoclonal antibody that targets VEGFR-2 and blocks the interaction of VEGF ligands and VEGFR-2. A phase 3 trial demonstrated a significant improvement in progression-free survival and overall survival when ramucirumab was combined with docetaxel as second-line therapy in patients who had pro­ gressed on platinum-based chemotherapy. Contrary to bevaci­ zumab, ramucirumab was safe in patients with both squamous and nonsquamous NSCLC and is approved regardless of histology. Many new agents are being developed and tested in clinical trials for second-line and beyond therapy in the metastatic setting, including novel immune checkpoint agents, antibody-drug conjugates, and even cellular therapies. Improved therapies in this setting remain an area of great need for patients with lung cancer. Supportive Care  No discussion of the treatment strategies for patients with advanced lung cancer would be complete without a mention of supportive care. Coincident with advances in chemo­ therapy and targeted therapy was a pivotal study that demonstrated that the early integration of palliative care with standard treatment TABLE 83-13  Results of Phase 3 Trials Comparing First-Line Immunotherapy with or without Chemotherapy Versus Chemotherapy Alone in Patients with NSCLC STUDY THERAPY NO. OF PATIENTS OS (MONTHS) PFS (MONTHS) KEYNOTE-024 Pembrolizumab 30.0 7.9 PD-L1 ≥50% Platinum-chemotherapy 14.2 3.5 KEYNOTE-042 Pembrolizumab 16.7 5.4 PD-L1 ≥1% Platinum-chemotherapy 12.1 6.5 IMPOWER 110 Atezolizumab 20.2 8.1 PD-L1 ≥50% TC or ≥15% IC Platinum-chemotherapy 13.1 5.0 KEYNOTE-189 Pembrolizumab + platinum-chemotherapy NR 8.8 Nonsquamous Platinum-chemotherapy 11.3 4.9 KEYNOTE-407 Pembrolizumab + platinum-chemotherapy 15.9 6.4 Squamous Platinum-chemotherapy 11.3 4.8 IMPOWER 150 Atezolizumab + platinum-chemotherapy 19.2 8.3 Nonsquamous Platinum-chemotherapy 14.7 6.8 IMPOWER 130 Atezolizumab + platinum-chemotherapy 18.6 7.0 Nonsquamous Platinum-chemotherapy 13.9 5.5 EMPOWER-Lung 3 Cemiplimab + platinum-chemotherapy Platinum-chemotherapy CheckMate 227 Nivolumab + ipilimumab 17.1 5.1 PART 4 Oncology and Hematology Platinum-chemotherapy 13.9 5.6 CheckMate-9LA Nivolumab + ipilimumab plus two cycles of platinum-chemotherapy Platinum-chemotherapy 10.7 POSEIDON Tremelimumab + durvalumab and platinum-chemotherapy Platinum-chemotherapy Abbreviations: IC, immune cells; NR, not reported; NSCLC, non-small-cell lung cancer; OS, overall survival; PFS, progression-free survival; TC, tumor cells. Note: Platinum-chemotherapy refers to first-line platinum doublet or triplet chemotherapy. strategies improves both quality of life and overall survival for patients with stage IV NSCLC (Chaps. 13 and 74). Aggressive pain and symptom control are important components of optimal treat­ ment of these patients. TREATMENT Small-Cell Lung Cancer The overall treatment approach to patients with SCLC is shown in Fig. 83-8. SURGERY FOR LIMITED-DISEASE SCLC SCLC is a highly aggressive disease characterized by its rapid doubling time, high growth fraction, early development of dis­ seminated disease, and dramatic response to first-line chemo­ therapy and radiation. In general, surgical resection is not routinely recommended for patients because even patients with LD-SCLC still have occult micrometastases. However, the American College of Chest Physicians Evidence-Based Clinical Practice Guidelines recommend surgical resection over nonsurgical treatment in SCLC patients with clinical stage I disease after a thorough evaluation for distant metastases and invasive mediastinal stage evaluation (grade 2C). After resection, these patients should receive platinum-based adjuvant chemotherapy (grade 1C). If the histologic diagnosis of SCLC is made in patients on review of a resected surgical specimen, such patients should receive standard SCLC chemotherapy as well. CHEMOTHERAPY In patients with limited-stage SCLC, concurrent chemoradiother­ apy with cisplatin-etoposide for four cycles has remained standard of care for over 4 decades. Two randomized phase 3 trials have demonstrated that chemotherapy with either cisplatin or carbo­ platin plus either etoposide and a PD-L1 inhibitor, atezolizumab (IMPOWER 133) or durvalumab (CASPIAN), provides superior progression-free and overall survival compared to chemotherapy 21.9 13.0 8.2 5.0 14.1 6.8 11.7 6.2 4.8 alone, making combination therapy the preferred choice in appro­ priate patients. Despite response rates to first-line therapy as high as 80%, the median survival ranges from 12 to 20 months for patients with LD and ~12 months for patients with ED. Regardless of disease extent, the majority of patients relapse and develop chemotherapyresistant disease. The prognosis is especially poor for patients who relapse within the first 3 months of therapy; these patients are said to have chemotherapy-resistant disease. Patients are said to have sensitive disease if they relapse >3 months after their initial therapy and are thought to have a somewhat better overall survival. These patients also are thought to have the greatest potential benefit from second-line chemotherapy. Topotecan and lurbinectedin are FDAapproved agents for second-line therapy in patients with SCLC. Topotecan has only modest activity and can be given either intra­ venously or orally; it appears to have more efficacy in patients with chemotherapy-sensitive disease. Lurbinectedin has a 35% response rate and progression-free survival of 3.5 months, with a greater ben­ efit in patients with chemotherapy-sensitive disease. Other agents with similar low levels of activity in the second-line setting include irinotecan, paclitaxel, docetaxel, vinorelbine, oral etoposide, and gemcitabine. The treatment of refractory SCLC is a pressing con­ cern, prompting the investigation of various new targets and drugs. For example, at the time this chapter is being written, one of the most exciting advancements in SCLC is the development of deltalike ligand 3 (DLL3)-targeting agents. For example, in the phase 2 DeLLphi-301 study, tarlatamab, a bispecific T-cell engager immu­ notherapy targeting DLL3 and CD3, demonstrated a 40% objective response rate and a median progression-free survival of 4.9 months in the 10-mg group for patients with previously treated SCLC. Con­ firmatory evidence from the phase 3 study remains pending. THORACIC RADIATION THERAPY Thoracic radiation therapy (TRT) and concurrent chemotherapy with curative intent are standard for patients with limited-stage SCLC with suitable performance status. Without TRT, virtually Complete history and physical examination Determination of performance status and weight loss Complete blood count with platelet determination Measurement of serum electrolytes, glucose, and calcium; renal and liver function tests CT scan of chest, abdomen, and pelvis or CT-PET to evaluate for metastatic disease MRI of brain Bone scan if not able to do PET scan No signs, symptoms, or imaging to suggest metastatic disease Patient has no contraindication to combined chemotherapy and radiation therapy Patient has contraindication to combined chemoradiation therapy Combined-modality treatment with platinum-based therapy and etoposide and radiation therapy Sequential treatment with chemotherapy and radiation therapy FIGURE 83-8  Algorithm for management of small-cell lung cancer. MRI, magnetic resonance imaging; PET, positron emission tomography. all patients with limited-stage SCLC will progress on systemic therapy alone within 1 year. Meta-analyses indicate that chemo­ therapy combined with TRT improves 3-year survival by ~5% com­ pared with chemotherapy alone. The 5-year survival rate, however, remains low at ~29–34%. Most commonly, TRT is combined with concurrent platinum and etoposide because of a better toxicity pro­ file compared to anthracycline-based regimens. For limited-stage SCLC, concurrent chemoradiation is more effective than sequential chemoradiation but is associated with significantly more esophagi­ tis and hematologic toxicity. Ideally, TRT should be administered by the second cycle of chemotherapy because later application appears slightly less effective. If for reasons of fitness or availability con­ current chemoradiation cannot be administered, TRT should fol­ low induction chemotherapy in alignment with an extensive-stage SCLC paradigm. With respect to fractionation of TRT, twice-daily 1.5-Gy fractioned radiation therapy has been shown to improve survival in limited-stage SCLC patients but is associated with higher rates of grade 3 esophagitis and pulmonary toxicity. Patients should be carefully selected for concurrent chemoradiation therapy based on good performance status and adequate pulmonary reserve. The role of radiotherapy in ED-SCLC is mainly limited to palliation of tumor-related symptoms such as bone pain and bronchial obstruc­ tion. Notably, consolidation TRT has demonstrated a survival benefit in extensive-stage SCLC in prospective studies; however, translating these study findings into current clinical practice is challenging due to their completion before the introduction of immunotherapy in the first-line setting. PROPHYLACTIC CRANIAL IRRADIATION Prophylactic cranial irradiation (PCI) has historically been offered to all patients with SCLC without progression on initial treat­ ment for limited-stage and extensive-stage disease. A meta-analysis including seven trials and 987 patients with limited-stage SCLC who had achieved a complete remission after upfront chemotherapy yielded a 5.4% improvement in overall survival for patients treated Single lesion detected on imaging Multiple lesions detected on imaging Biopsy lesion Negative for metastatic disease Positive for metastatic disease CHAPTER 83 Chemotherapy with immunotherapy and/or radiation therapy for palliation of symptoms Neoplasms of the Lung with PCI. However, the role of PCI has become controversial as these studies were conducted before brain MRIs for staging. In patients with ED-SCLC who have responded to first-line chemo­ therapy and had no CNS disease, patients randomized to observa­ tion had a higher incidence of brain metastases; however, use of PCI did not improve overall survival. THYMIC TUMORS Thymic tumors are rare malignancies, accounting for 0.5–1.5% of all malignancies in the United States with a higher incidence among Asian populations. They are particularly rare among children and young adults with incidence peaking in the fifth decade of life. There is no difference between sexes, and no clear risk factors have been identified. ■ ■CLINICAL MANIFESTATIONS The majority of thymic tumors occur in the anterior mediastinum. Approximately 40% of patients with mediastinal masses will be asymptomatic with an incidental finding on chest imaging. In patients presenting with an anterior mediastinal mass, if appropriate, serum β-human chorionic gonadotropin (HCG) and α-fetoprotein (AFP) should be sent to rule out a germ cell tumor. A patient with a sign or symptom of thymoma or thymic carcinoma may present with chest pain, dyspnea, cough, or superior vena cava syndrome secondary to effects on adjacent organs or a paraneoplastic syndrome, most commonly myasthenia gravis, pure red cell aplasia, or hypogam­ maglobulinemia. More rare paraneoplastic syndromes include limbic encephalitis, aplastic anemia, hemolytic anemia, and autoimmune disease such as Sjögren’s syndrome, polymyositis, rheumatoid arthritis, and ulcerative colitis, among others. ■ ■STAGING Given the rarity of the tumor, patients with suspected thymoma should be evaluated by a multidisciplinary team including a surgeon, medical and radiation oncologist, and pathologist with experience in treating the disease. A CT scan of the chest with contrast is recommended to # 13 - 84 Breast Cancer ### 84 Breast Cancer TABLE 83-14  Staging Thymic Tumors MASAOKA STAGE DEFINITION I Grossly and microscopically encapsulated IIA Microscopic transcapsular invasion IIB Macroscopic invasion into surrounding tissue excluding pericardium, lung, and great vessels III Macroscopic invasion into neighboring organs of the lower neck or upper chest IVA Pleural or pericardial dissemination IVB Hematogenous or lymphatic dissemination to distal organs WHO A Tumor with few lymphocytes AB Tumor with features of type A and foci rich in lymphocytes B1 Tumor with features of normal epithelial cells with vesicular nuclei and distinct nucleoli and an abundant population of lymphocytes. Also known as cortical thymoma, lymphocyte-rich thymoma B2 Thymoma with no or mild atypia with round or polygonalshaped cells with small component of lymphocytes B3 Well-differentiated thymic carcinoma with mild atypia C Thymic carcinoma with high atypia PART 4 Oncology and Hematology determine if the mass is resectable based on relationship to surround­ ing structures. An MRI with contrast may be performed if clinically indicated. A PET scan may be useful in the evaluation of a patient with thymic tumors, although it may be less useful in the staging of thymoma compared to thymic carcinoma. A core needle biopsy is considered standard of care for obtaining a histologic diagnosis of an anterior mediastinal tumor. This may be obtained via CT or ultrasound imaging. However, in some circumstances, a mediastinoscopy or open biopsy may be required. Thymomas are commonly staged using the Masaoka system or the WHO staging system, as described in Table 83-14. WHO types A, AB, and B1 tend to be more well-differentiated, types B2 and B3 are mod­ erately differentiated, and type C is poorly differentiated. ■ ■TREATMENT Surgical resection is the mainstay of treatment for patients with Masa­ oka type I and II thymic tumors. In patients with type III and IV who have potentially resectable thymic tumors, neoadjuvant chemotherapy may be given to decrease the tumor size and allow for a resection with negative margins. Surgery remains controversial and provides a limited role in the treatment of stage III and IV disease. No additional therapy may be required in patients with type I who have a resection with nega­ tive margins. Postoperative radiation therapy may be recommended based on extracapsular extension and the presence of positive margins in patients with type II or III thymic tumors or histologic evaluation WHO B3 and C. Radiation therapy may be beneficial in patients with locally advanced disease (type III or IV) or in patients with symptoms secondary to compression of surrounding structures. Chemotherapy with cisplatin, doxorubicin, and cyclophosphamide (CAP) remains the mainstay of therapy in the neoadjuvant and adjuvant setting as well as first-line therapy in patients with metastatic thymoma, whereas carboplatin and paclitaxel are often employed in patients with thymic carcinoma. Limited additional agents are recommended based on small phase 2 trials as second-line therapy and beyond. SUMMARY The management of SCLC and NSCLC has undergone major change in the past decade, resulting in a reduction in lung cancer mortality. For patients with early-stage disease, advances in radiotherapy and surgical procedures as well as new systemic therapies in the neoadjuvant and perioperative settings have greatly improved prognosis in all diseases. For patients with advanced lung cancer, major progress in understand­ ing tumor genetics and tumor immunology has led to the development of rational targets and specific inhibitors, which have documented efficacy in specific subsets of NSCLC. Furthermore, increased under­ standing of how to activate the immune system to drive antitumor immunity has proven to be a successful therapeutic strategy for a subset of patients with advanced lung cancer. However, only a small subset of patients responds to immune checkpoint inhibitors, and the majority of patients treated with targeted therapies or chemotherapy eventually develop resistance, which provides strong motivation for further research and enrollment of patients onto clinical trials in this rapidly evolving area. Acknowledgment David Johnson, Leora Horn, and Wade Iams contributed to this chapter in the prior edition and material from that chapter has been retained here. ■ ■FURTHER READING Cascone T et al: Perioperative nivolumab in resectable lung cancer. N Engl J Med 390:1756, 2024. Ettinger D et al: NCCN Guidelines® Insights: Non-Small Cell Lung Cancer, Version 2.2023. J Natl Compr Canc Netw 21:340, 2023. Hsu M et al: Lung cancer survivorship: Physical, social, emotional, and medical needs of NSCLC survivors. J Natl Compr Canc Netw 22:e237072, 2024. Owen D et al: Therapy for stage IV non-small-cell lung cancer with driver alterations: ASCO Living Guideline, Version 2023.2. J Clin Oncol 41:e63, 2023. Rudin C et al: Small-cell lung cancer. Nature Rev Dis Primers 7:3, 2021. Wakelee H: Chemotherapy and immunotherapy in early-stage NSCLC: Neoadjuvant vs adjuvant therapy. Clin Adv Hematol Oncol 21:648, 2023. Nancy E. Davidson Breast Cancer Breast cancer is the most common nonskin cancer diagnosed in women in the world. In 2024, it is estimated that in the United States 310,000 women will be diagnosed with invasive breast cancer, >56,000 women will receive a diagnosis of ductal carcinoma in situ (DCIS), and about 42,250 women will die from breast cancer. Although largely a disease of women, about 2800 men will be diagnosed with and 530 men will die from breast cancer in 2024 in the United States. Thanks to advances in understanding of breast cancer biology, screening, diag­ nosis, treatment, and decreased use of hormone replacement therapy, 5-year relative survival in the United States is currently 91%. These advances have also made it possible to conceptualize the evolution of breast cancer and how available interventions can be applied across the continuum of changes to improve outcomes (Fig. 84-1). EPIDEMIOLOGY AND RISK FACTORS ■ ■NONGENETIC RISK FACTORS Female gender and increasing age are the most common risk factors for breast cancer. About 70% of breast cancer in the United States is diag­ nosed in women 55 years and older, and median age of diagnosis is 63. Incidence is highest in non-Hispanic whites followed by non-Hispanic blacks and is lower in Hispanic, Asian/Pacific Islander, and American Indian/Alaska Native women; in contrast, mortality is highest in nonHispanic blacks followed by non-Hispanic whites and individuals of other race/ethnicity. Both incidence and mortality vary considerable around the globe, but studies of immigrant populations show that pop­ ulations who migrate from low-incidence regions to high-incidence regions will attain the breast cancer risk of the higher incidence region within one or two generations. Breast cancer continuum High risk In situ Invasive Micro-metastases Detectable metastases Mortality Normal Ductal carcinoma in situ Normal duct Intraductal hyperplasia Atypical ductal hyperplasia Risk assessment Risk reduction/chemoprevention Screening Primary Rx (surgery/radiation) FIGURE 84-1  Breast cancer continuum conceptual model. Most breast cancers begin in epithelial cells within the lobules or ducts. They proceed through a continuum of atypia and hyperplasia to in situ malignancy to invasion into surrounding normal tissues followed by intravasation into lymph and blood channels to local lymph nodes and distant organs, culminating in distant metastases. This is a conceptual model. Not all metastatic breast cancers have progressed through these stages, and many lesions do not progress to the next. Breast cancer is predominantly a disease resulting from prolonged exposure of the breast to estrogen. Thus, early menarche, late meno­ pause, and late first pregnancy are known risk factors. Likewise, pro­ longed exposure to hormone replacement therapy (but paradoxically not estrogen replacement therapy) is associated with increased risk as is current use of oral contraceptives. Postmenopausal obesity (but not premenopausal obesity) is also a risk factor, likely because of increased estrogen exposure. Studies of diet and breast cancer risk have not been conclusive, but alcohol consumption is a risk factor. The best documented exogenous risk factor for breast cancer is exposure to ionizing radiation during adolescence. Studies of other environmental factors such as pesticide or other chemical exposures have not been convincing. Women diagnosed with some types of benign breast pathology also have a higher risk of subsequent invasive breast cancer diagnosis. In particular, the diagnosis of atypical ductal or lobular hyperplasia increases risk about four- to fivefold, whereas a diagnosis of lobular carcinoma in situ (LCIS) increases risk 7- to 12-fold. Recent studies also suggest that women with high breast density on mammography may be at increased risk of breast cancer. ■ ■GENETIC RISK FACTORS Family history is a critical risk factor, although only 20% of women diagnosed with breast cancer have a family history. Diag­ nosis of breast cancer in a first-degree relative (parent, sibling, or daughter) doubles breast cancer risk. A personal diagnosis of previous invasive breast cancer also increases the risk of developing a new breast cancer in the ipsilateral or contralateral breast. Prevention, diagnosis, and management of breast cancer have been revolutionized by the identification of a family of hereditary breast cancer susceptibility genes that account for 5–10% of breast cancers. These genes play a role in DNA damage repair, and inherited muta­ tions, which are transmitted in an autosomal dominant fashion, Regional lymph node Lymph or blood vessels Invasive ductal cancer Distant organs Distant organs CHAPTER 84 Adjuvant Systemic Rx Breast Cancer Survivorship Palliative treatment generally lead to protein truncation and loss of function of DNA repair proteins. The most common mutations are in the BRCA1 (located on chromosome 17q21) or BRCA2 (located on chromosome 13q12) genes, and they impart a 50–80% risk of developing invasive breast cancer by age 80 years as well as a 30% risk of developing ovarian cancer. Germline mutations in other genes also lead to a higher risk of breast cancer including TP53 (Li-Fraumeni syndrome), PALB2, ATM, STK11 (Peutz-Jeghers syndrome), and PTEN (Cowden syndrome). Certain populations have a higher incidence of BRCA mutations, especially Ashkenazi Jews. Commercially available assays for germline, breast cancer susceptibility mutations have expanded from just the two originally discovered genes (BRCA1/2) to panels including these and the genes listed above to panels that include these and 20 or more additional genes. Two major concerns have arisen over time regarding the relative lack of clinical correlations inherent in these panels and the unknown association with risk, which have led to some confusion and discomfort among patients: (1) variants of unknown significance (VUS) in the genes known to be associated with increased risk; and (2) genes included in the panels about which little is known regarding clinical risk. Efforts to develop polygenic risk scores that evaluate single nucleotide polymorphisms (SNPs) in other genes are under study but are not yet ready for clinical application. Testing for germline mutations is readily done using panel testing on DNA obtained from peripheral blood or saliva after appropriate coun­ seling. It is not recommended for the general population. Evidencebased guidelines from the American Society of Clinical Oncology and Society of Surgical Oncology recommend consideration of testing for high-penetrance breast cancer susceptibility genes in individuals with a personal history of breast cancer with specific features including diagnosis ≤65 years. Older patients should be offered testing for clini­ cal features such as Ashkenazi Jewish ancestry; multiple breast cancers; certain types of breast cancer, including breast cancer lacking expres­ sion of the estrogen and progesterone receptors and HER2 proteins (triple-negative breast cancer [TNBC]) and lobular breast cancer with personal or family history of diffuse gastric cancer; or close blood rela­ tive with early-onset or male breast cancer, ovarian cancer, pancreatic cancer, or metastatic prostate cancer. Testing for individuals without a cancer diagnosis should be considered for those with a family member who tests positive or those with a family history as outlined above or those with higher risk based on existing risk assessment tools such as Tyrer-Cuzick score, BRCAPro, or CanRisk. PREVENTION Current strategies to prevent breast cancer include surgery, chemo­ prevention, and lifestyle modification; their use and impact will vary depending on the underlying risk of developing breast cancer. ■ ■PROPHYLACTIC SURGERY Prophylactic mastectomy reduces risk of developing breast cancer by about 90% including in individuals who carry a germline breast cancer susceptibility gene mutation. Women who opt for prophylactic mastectomy in this setting should be counseled that breast cancer may develop in residual breast tissue. However, preventive mastectomy is not likely to improve outcomes in women with low or only modest risk and should be discouraged. Though the primary role for prophylactic oophorectomy is for ovarian cancer prevention in germline mutation carriers, it can also reduce breast cancer incidence in premenopausal women by about 50% because of reduction in estrogen exposure. PART 4 Oncology and Hematology ■ ■CHEMOPREVENTION Ample evidence exists for the use of chemoprevention approaches that target estrogen signaling pathways in high-risk women. Tamoxifen reduces risk of invasive breast cancer in women at higher risk (≥60 years, diagnosis of LCIS, or younger women with risk of developing invasive breast cancer ≥1.67% over 5 years based on current risk assessment tools). Newer data suggest that low-dose tamoxifen for 3 years may be effective and well tolerated. Side effects include postmenopausal symp­ toms and increased risk for endometrial cancer and thromboembolic events, especially in women over 50. Raloxifene may be an alternative for postmenopausal women. Though less effective in reducing breast cancer risk than tamoxifen, it is associated with fewer uterine cancers. The aromatase inhibitors, exemestane or anastrozole, also reduce breast cancer incidence by about 50% in postmenopausal women who are at moderate-high risk for breast cancer. The U.S. Preventive Services Task Force recommends that clinicians offer risk-reducing medications like tamoxifen, raloxifene, or aromatase inhibitors to women who are at increased risk for breast cancer and at low risk for medication side effects. Uptake is low despite the substantial evidence that demonstrates a huge benefit. ■ ■LIFESTYLE MODIFICATION Potential lifestyle modifications to reduce breast cancer risk include maintenance of a normal body mass index, avoidance of alcohol, and minimizing use of hormone replacement therapy. Regular exercise, especially during adolescence, may be associated with reduced risk. Long-term follow-up from the dietary substudy of the Women’s Health Initiative showed that a low-fat diet in postmenopausal women who were cancer-free at the time of study enrollment resulted in a nonsig­ nificant reduction in breast cancer incidence but appeared to reduce risk of death from breast cancer. The role of newer GLP-1 agents has not been studied. SCREENING Breast cancer screening has been an area of active investigation and controversy for decades. Issues include lack of consensus around the goal of screening, the target population (e.g., age, risk), and the type and frequency of screening. Multiple guidelines exist and continue to evolve. Initial trials focused on three modalities: breast self-exam, clini­ cal breast exam (CBE), and mammography. Though widely promoted in the past, emphasis on breast self-exam has waned, in part because of two randomized clinical trials in China and Russia that showed no benefit. In contrast, a randomized trial in India of CBE every 2 years in women aged 35–64 years with no history of breast cancer indicated that CBE led to a significant reduction in the proportion of women diag­ nosed with stage III or IV disease and a nonsignificant 15% reduction in breast cancer mortality, largely in women ≥50 years. Nine randomized trials have studied screening mammography. In aggregate, they demonstrated that screening mammography reduced breast cancer mortality by about 20–25% in women ≥50 years without an impact on overall mortality. The UK Age trial suggested a simi­ lar benefit for women who began screening at 40 years. Screening frequency has varied from 1–2 years across trials. Mammography techniques have evolved over the years, and a current U.S. trial is evaluating the role of tomosynthesis as a means of improving ben­ efit from mammography. Multiple guidelines exist and continue to evolve. Most recommend that women aged 50–70 years have mam­ mography every 1–3 years, and many recommend screening for women aged 40–50 years as well. When to stop is not known, but it is generally accepted that benefits are limited to women with a predicted life expectancy of at least 10 years. The role of magnetic resonance imaging (MRI) as a screening modality is less well studied. MRI is more sensitive, less specific, and more complex to perform. Some guidelines suggest that it be used for women who have a lifetime predicted risk of ≥20%, which includes those with germline pathogenic mutations in the BRCA genes. Its use has also been suggested for those with very dense breasts on mam­ mography, but clear evidence of benefit is lacking. Screening ultra­ sound has also been studied, but evidence supporting its routine use is lacking. There is considerable interest in the use of multicancer early detec­ tion (MCED) tests using circulating DNA as a screening test for dis­ eases like breast cancer. Initial studies have not shown that these tests can substitute for or augment conventional mammographic screening, and women who do have MCED assays performed should still undergo mammographic screening, even if the MCED test is negative. DIAGNOSIS AND STAGING Clinical signs and symptoms suggestive of breast cancer may include a breast lump or skin or nipple changes or palpable regional nodes. Thanks to mammographic screening, many patients present with abnormal mammographic findings including a mass, distortion, and/ or suspicious microcalcifications without any symptoms or physi­ cal exam findings. Figure 84-2 shows an algorithm for diagnostic evaluation of breast abnormalities noted on physical exam or imaging. Final diagnosis rests on pathologic confirmation, which is generally carried out by image-guided core biopsy to confirm diagnosis, assess tumor grade and morphology, and carry out biomarker evaluation for expression of estrogen receptor (ER) and progesterone receptor (PR) and HER2 proteins and potentially HER2 gene amplification. Suspi­ cious axillary lymph nodes should also be biopsied via image-guided techniques. It is important to image both breasts because up to 3% of women with newly diagnosed breast cancer have unsuspected con­ tralateral disease. Evaluation of the breasts with MRI after a biopsyproven diagnosis is controversial. On the one hand, MRI is more sensitive than radiologic mammography and will commonly detect previously unidentified disease. On the other hand, this observation may lead to additional surgery, including mastectomy, without obvious improvements in outcomes. Staging is a cornerstone for breast cancer management because it provides information about natural history and informs decisions about therapy. The traditional TNM (tumor-node-metastasis) staging system has evolved to consider molecular testing including biomarkers as above and certain genomic tests such as the Oncotype 21 gene assay. Staging may take place at time of diagnosis (c or clinical staging) or after surgery (p or pathologic staging) or after preoperative systemic therapy followed by surgery (designated with a “y” prefix). For most asymptomatic individuals presenting with early breast cancer, a careful history and physical exam will be sufficient, and testing can be limited to breast imaging and any testing needed to ensure a safe surgical procedure. Individuals who present with symptoms suggestive of meta­ static disease or physical findings of more advanced disease (e.g., large Diagnostic Evaluation of the Breast Suspicious clinical breast finding Suspicious breast finding Diagnostic breast imaging mammography ultrasonography MRI (if indicated) Negative/benign Ductal carcinoma in situ with microcalcifications Follow-up exam Uncertain or clinical suspicion persists Resolved Refer to experienced breast diagnostician Routine follow-up screening mammogram as indicated FIGURE 84-2  Evaluation and workup of breast lesions. For more extensive details, see https://www.nccn.org/professionals/physician_gls/pdf/breast-screening.pdf. (Mammographic images courtesy of Drs. Mark Helvie and Colleen Neal, Department of Radiology, Michigan Medicine. Photomicrographs courtesy of Dr. Celina Kleer, Department of Pathology, Michigan Medicine.) tumor, skin changes, extensive regional adenopathy) should undergo radiologic imaging with computed tomography and radionuclide scanning to look for overt metastatic disease. Suspicious lesions should be biopsied whenever possible to confirm a diagnosis of metastatic breast cancer because of the implications for prognosis and selection of therapy. Less than 10% of patients present with de novo metastatic breast cancer. Breast cancer staging is currently carried out according to the guide­ lines of the American Joint Committee on Cancer (AJCC) eighth edi­ tion. Conceptually, stages I and II represent early-stage disease, which is confined to breast and ipsilateral nodes, whereas stage III comprises locally advanced breast cancer and stage IV denotes de novo meta­ static breast cancer, designated as M1 in the current staging system. Common sites for breast cancer metastasis include soft tissues, lung, bone, liver, and brain. One study suggested that M1 disease can be further divided into at least four subgroups with substantially different prognoses, based on sites and burden of disease as well as biological features. However, these findings have not yet been incorporated into the formal AJCC staging system. Outcomes are directly related to stage at presentation and vary by race and ethnicity in the United States, as shown in Table 84-1. Screening breast imaging No suspicious breast finding Suspicious mass Suspicious microcalcifications Routine follow-up screening mammogram as indicated CHAPTER 84 Confirmed suspicious finding Invasive ductal carcinoma Biopsy Breast Cancer Progesterone receptor (PR) positive HER2 negative Estrogen receptor (ER) positive CURRENT UNDERSTANDING OF BREAST CANCER BIOLOGY AND CLINICAL IMPLICATIONS It is now accepted that invasive breast cancer is in fact a disease with diverse subtypes, both histologic and molecular. Two decades of molecular analyses have documented multiple transcriptional, epi­ genetic, and genetic changes that characterize invasive breast cancer. TABLE 84-1  Five-Year Breast Cancer Relative Survival Rate (%) by Stage at Diagnosis and Race/Ethnicity in United States from 2012–2018a STAGE ALL WHITE BLACK AIAN HISPANIC API I >99 >99 >99 >99 >99 >99 II III IV aRace is exclusive of Hispanic origin. Abbreviations: AIAN American Indian/Alaska Native; API Asian/Pacific Islander. Source: Adapted from AN Giaquinto et al: Breast cancer statistics, 2022. CA Cancer J Clin 72:524, 2022. This has led to the division of invasive breast cancer into at least four major molecular subtypes. Luminal A and B subtypes both express ER and are viewed as generally likely to be responsive to antiestrogen strategies (also called hormonal or endocrine therapies). However, luminal B tumors are characterized by other findings such as reduced PR expression or increased proliferation, usually measured by expres­ sion of Ki67, and are associated with a poorer outcome than luminal A tumors. The HER2 subtype expresses HER2 protein at high levels and is more likely to benefit from the use of HER2-targeted therapies. Basal tumors tend to lack expression of ER, PR, and HER2 proteins (TNBC). TNBCs carry a poorer prognosis and are generally managed with chemotherapy and immunotherapy. TNBC can be further divided into at least six subtypes, which may also have therapeutic implications, especially in the metastatic setting. Pathologic evaluation of a breast cancer specimen begins with an assessment of morphology. Most invasive breast cancers are ductal, but about 10–15% are lobular histologies. Lobular cancers are usually ER positive and HER2 negative. They are distinguished by absence of E-cadherin staining or function, and they have a different natural his­ tory, with a propensity to spread to serosal surfaces, including omen­ tum, pleura, and meninges or to various parenchyma, such as ovaries and upper and lower gastrointestinal tracts. This curious site for meta­ static recurrence may result in unusual clinical presentations that may delay diagnosis if metastatic disease is not considered. Other special subtypes are also recognized such as mucinous, medullary, papillary, and metaplastic histologies. Mucinous and pure medullary cancers (distinguished by high levels of lymphocytic invasion surrounding the tumor) are associated with very favorable prognoses with local therapy only. Metaplastic cancers may present as very poorly differentiated tumors or even as squamous or sarcomatoid differentiations. They are generally approached as ductal cancers but may be treated in a manner consistent with their relative subtypes, such as squamous or sarcoma-like differentiation. Tumor grade is also assessed using stan­ dard approaches such as Nottingham grade, ranging from grade 1 to 3; higher grade is generally associated with poorer prognosis. PART 4 Oncology and Hematology Further profiling of the primary tumor specimens may follow depending on the clinical circumstances. Early-stage ER-positive breast cancers are often evaluated by genomic transcriptional profiling assays to identify patients with such a favorable prognosis that adjuvant chemotherapy in addition to endocrine therapy is not needed; five of these are recommended by the American Society of Clinical Oncol­ ogy: Oncotype Dx (21 genes), MammaPrint (70 genes), ProSigna (50 genes), EndoPredict (12 genes), and Breast Cancer Index (two genes plus a proliferation signature). Although any one of these appears to be relatively accurate in terms of prognosis, they do not measure the same thing and they have not been compared head-to-head. Therefore, ordering more than one assay for a single case is discouraged. At pres­ ent, more detailed molecular analysis is usually restricted to metastatic tumor specimens to identify molecular alterations that are associated with response to specific targeted therapies, as discussed in the section on treatment of metastatic breast cancer. TREATMENT Breast Cancer MANAGEMENT OF IN SITU BREAST CANCER Ductal Carcinoma In Situ (DCIS)  Routine use of screening mam­ mography has led to a marked increase in the diagnosis of DCIS and LCIS. Untreated DCIS (which is confined to the duct without evidence of invasion through the basement membrane into sur­ rounding interstitial tissue) is associated with a 30% risk of devel­ oping a subsequent invasive cancer in the same breast. Therapy is generally focused on excision of the lesion to negative margins and to confirm absence of invasion; evaluation of axillary lymph nodes is not generally undertaken. Excision may be followed by radiother­ apy to the ipsilateral breast and consideration of endocrine therapy if the DCIS expresses ER protein to reduce risk of breast recurrence or contralateral primary. Patients with extensive DCIS may require mastectomy, whereas those with a small disease burden may opt for excision alone with regular mammographic surveillance. Molecular assays that can predict lack of benefit from radiotherapy after exci­ sion are sometimes used. Lobular Carcinoma In Situ (LCIS)  LCIS is often an incidental find­ ing on a breast biopsy done for abnormalities on physical exam or mammography. It is viewed as a marker for increased risk of devel­ oping invasive breast cancer as about 25–30% of women with LCIS subsequently develop invasive disease in either breast. The primary management is continued breast cancer screening and consider­ ation of chemoprevention with tamoxifen or aromatase inhibitor to decrease risk of invasive disease. Bilateral prophylactic mastectomy is sometimes considered but should be generally limited to those who have other risk factors or concerns. TREATMENT OF EARLY-STAGE BREAST CANCER Multidisciplinary care is a cornerstone for optimal treatment of early breast cancer. The current approach to treatment of earlystage breast cancer reflects evolution from the initial concept of breast cancer as an orderly disease that spreads from breast to axillary nodes to systemic disease to our current understanding of breast cancer as a potentially systemic disease almost from onset. Therefore, treatment approaches incorporate surgery and radiation to treat local disease and systemic therapy to eliminate or suppress any microscopic distant disease. The goal of these treatments in early-stage disease is reduction of subsequent distant recurrence and mortality. They are given in a manner to optimize efficacy while minimizing toxicity and avoiding overtreatment. Surgery  Six randomized trials have demonstrated equivalent sur­ vival with the use of breast-conservation therapy (lumpectomy and, usually, radiotherapy to the remaining breast) or modified radical mastectomy for individuals with early-stage breast cancer. Contra­ indications to breast conservation include patient preference, poor cosmesis, multifocal disease, previous chest radiation, and ongoing pregnancy that prevents timely administration of radiotherapy. Though not an absolute contraindication, germline mutation in a member of the BRCA gene family can drive a decision for bilat­ eral mastectomy because of the high risk of subsequent disease in either breast. Patients who require or choose mastectomy should be informed about availability of immediate or delayed reconstruction options using autologous tissue or implants as clinically appropri­ ate. It is clear, though, that most women with early breast cancer are well served by a lumpectomy to negative margins with axillary management, followed by radiation as appropriate. Management of the ipsilateral axilla continues to evolve as well. For patients with small tumors and clinically negative axillary nodes, sentinel node localization is used to identify clinically rel­ evant nodes for removal and pathologic assessment to finalize stag­ ing and inform decisions about extent of radiotherapy and selection of adjuvant systemic therapy. Use of axillary dissection (removal of level 1 and 2 lymph nodes) is restricted to individuals with palpable lymph nodes or those with substantial pathologic involvement of sentinel lymph nodes. Randomized trials have shown excellent outcomes with omission of any sentinel node evaluation for older women with small biologically favorable tumors and clinically negative axilla who will take adjuvant endocrine therapy as well as omission of axillary dissection for women with low tumor burden in sentinel nodes who will receive radiation. Radiation  As with surgery, the use of postoperative radiotherapy to minimize breast recurrence and nodal recurrence has also changed as a result of data accumulated from serial clinical trials. Current treatment strategies are tailored to the individual based on age, tumor size, and nodal status. Options for external-beam radiotherapy include a standard scheme of daily whole breast radiotherapy (WBR) for 4–6 weeks, hypofractionated schedules lasting 5 days to 3 weeks, or partial breast radiation, usually given in a hypofractionated regimen. Clinical trials of the latter have failed to demonstrate its benefit over WBR. Extension of the radiotherapy port to include regional and axillary nodes is also considered based on pathology and type of surgery. The safety of omitting radio­ therapy for women older than 65 with low-risk ER-positive tumors who will take endocrine therapy has been demonstrated. Brachy­ therapy to apply a radiation source directly to the tumor bed is also employed in some cases as a way of shortening duration of therapy. Patients who undergo mastectomy may also benefit from chest wall radiotherapy to reduce risk of both local and distant recur­ rence, thus improving survival. Potential candidates include those with large tumors or positive axillary lymph nodes, especially those with four or more involved nodes, while those with one to three positive nodes or close/minimally involved margins are also considered. Systemic Therapy  It has been recognized that breast cancer is often a systemic disease at time of diagnosis. Enhanced understand­ ing of breast cancer biology, including the concept that resistant clones evolve as a function of random mutations over time, and the identification of multiple targets of therapy have greatly refined our understanding of the role of systemic therapy in early breast cancer. Such therapy may be given preoperatively (neoadjuvant) or postoperatively (adjuvant) and may take the form of cytotoxic chemotherapy, endocrine therapy directed toward ER, and other targeted therapies such anti-HER2, poly (ADP-ribose) polymerase (PARP) inhibitors in cancers with BRCA1/2 mutations, and/or immunotherapy directed toward immune checkpoints. Treatment algorithms are constantly evolving based on results from clinical trials, and current evidence-based guidelines are available through groups like the National Comprehensive Cancer Network, American Society of Clinical Oncology, or European Society of Medical Oncology. SELECTION OF NEOADJUVANT VERSUS ADJUVANT SYSTEMIC THERAPY The primary goal of neoadjuvant therapy (also designated “pre­ operative” adjuvant therapy) compared to classic postoperative adjuvant therapy is to downsize tumor to make it more amenable to surgery. A second goal is to provide an in vivo assessment of tumor response to the selected systemic therapy and perhaps direct subsequent adjuvant therapy. Data suggest that individual patients who attain a complete pathologic response (pCR) to neoadjuvant therapy have a better outcome than those who do not, although randomized trials of adjuvant versus neoadjuvant therapy have not shown a difference in survival. At least one trial has demonstrated that patients who fail to experience a pCR to standard combination chemotherapy containing an anthracycline, an alkylating agent, and a taxane, especially those with TNBC, appear to benefit from subsequent capecitabine. Currently, neoadjuvant therapy with che­ motherapy and anti-HER2 agents is considered for individuals with HER2-positive tumors that are ≥2 cm or node-positive dis­ ease, while neoadjuvant therapy with chemotherapy and possibly the checkpoint inhibitor pembrolizumab are considered for indi­ viduals with TNBC ≥2 cm or node-positive disease. Neoadjuvant endocrine therapy can be used for postmenopausal women with ER- or PR-positive breast cancer to reduce extent of surgery or per­ haps avoid surgery for older women with multiple comorbidities. Women with small tumors of any subtype are often better served by initial surgery to establish pathologic stage followed by tailored selection of systemic therapy. Types of Systemic Therapy for Early Breast Cancer  Endocrine therapy is a mainstay for management of ER- and/or PR-positive invasive breast cancer; positive tumors are commonly defined as those with ≥1% staining by immunohistochemistry. Because of their mechanisms of action as blockers of interaction between estrogen ligand and ER, the selective ER modulators tamoxifen and toremi­ fene can be used in women with any menopausal status. In contrast, estrogen deprivation approaches depend on menopausal status. The use of aromatase inhibitors, such as anastrozole, letrozole, and exemestane, as monotherapy is restricted to postmenopausal women. Ovarian suppression by gonadotropin hormone–releasing hormone (GnRH), such as the luteinizing hormone–releasing hormone (LHRH) agonists goserelin or leuprolide, or alternatively surgical oophorectomy, can be used to reduce circulating estradiol levels in premenopausal women to postmenopausal levels. These women can then also be treated either with tamoxifen or an AI. The CDK4/6 inhibitors abemaciclib and ribociclib may be used in combination with endocrine therapy for high-risk, early-stage, ERpositive breast cancer. Multiple cytotoxic agents have shown efficacy for treatment of metastatic breast cancer and are now used in treatment of early-stage disease. The most common regimens include cyclophosphamide, doxorubicin, paclitaxel, docetaxel, 5-fluorouracil, methotrexate, and/ or one of the platin salt compounds (cisplatin or carboplatin). Several anti-HER2 therapies are also available. Two monoclonal antibodies, trastuzumab and pertuzumab, and two tyrosine kinase inhibitors, neratinib and lapatinib, are approved for use in earlystage breast cancer; multiple other agents are available for meta­ static disease, as discussed below, and are undergoing testing for use in earlier stages of disease. CHAPTER 84 The role of immunotherapy with the checkpoint inhibitors is also under evaluation. At present, pembrolizumab for patients with TNBC is the only U.S. Food and Drug Administration (FDA)- approved agent for early-stage breast cancer, but others are under investigation. A targeted agent, olaparib, an oral PARP inhibitor, is also used as an adjunct to chemotherapy for women with high-risk, germline BRCA-mutated, HER2-negative breast cancer who have completed (neo)adjuvant chemotherapy. It is particularly active in cancers with DNA repair pathway defects. Breast Cancer GENERAL GUIDELINES FOR (NEO)ADJUVANT SYSTEMIC THERAPY FOR EARLY BREAST CANCER Approach to ER- and/or PR-Positive Breast Cancer  Endocrine therapy is the foundation for adjuvant therapy for women with ER- and/or PR-positive breast cancer. Selection is based on menopausal status and consideration of side effect profiles. For premenopausal women with low-risk breast cancer, tamoxifen for 5–10 years is the standard. Premenopausal women with higher risk tumors are candidates for combined endocrine therapy with an LHRH agonist plus tamoxifen or aromatase inhibitor for 5 years. Multiple random­ ized trials have shown that aromatase inhibitors for 5 years provide modest but statistically significant superior outcome compared with tamoxifen for postmenopausal women. Women with ERpositive breast cancers are at risk for distant recurrence long after their original diagnosis, from 10–20 or more years. Some trials suggest that up to 10 years of endocrine therapy may be indicated for healthy postmenopausal women with higher risk tumors and good tolerance. Given the chronic nature of adjuvant endocrine therapy, careful attention to side effects is warranted. Tamoxifen is associated with postmenopausal symptoms and a small chance of thromboembolic events or uterine cancer, especially in women over 50 years. Aro­ matase inhibitors are associated with postmenopausal symptoms, arthralgias, and bone loss, while LHRH agonists are associated with postmenopausal symptoms and bone loss. Although the three aromatase inhibitors appear to be equally effective, tolerance may vary; patients who are intolerant of one aromatase inhibitor may benefit from change to another member of the family or tamoxifen. A critical decision in this setting is the value of chemotherapy in addition to endocrine therapy. Its absolute (as opposed to relative or proportional) benefit varies by menopausal status and nodal status. Genomic multigene expression testing of the tumor with assays like Oncotype, MammaPrint, ProSigna, EndoPredict, or Breast Cancer Index will identify a substantial portion of patients with zero to three positive nodes who would not benefit from adjuvant chemotherapy. Neoadjuvant chemotherapy should be administered to healthy individuals with a large tumor burden or more than three positive nodes, especially premenopausal patients with a primary goal of reducing tumor size. However, in ER-positive disease, the likeli­ hood of a pCR is low. Regardless, adjuvant chemotherapy (neoad­ juvant or standard) is considered for healthy individuals with four or more positive lymph nodes as well as for those with lesser nodal burden who have high genomic signature score. Established chemo­ therapy regimens are outpatient based and use multiple agents for 3–6 months with appropriate supportive care including antiemet­ ics and colony-stimulating factors as appropriate to reduce risk of febrile neutropenia. Long-term side effects can include premature menopause in premenopausal women and a small risk of doxorubicinrelated cardiomyopathy, taxane-related peripheral neuropathy, or secondary leukemia, and possible cognitive dysfunction. Women with node-positive or high-risk node-negative, ER- and/ or PR-positive, HER2-negative breast cancer who have completed adjuvant chemotherapy should consider use of a CDK4/6 inhibi­ tor in conjunction with endocrine therapy. Current information supports the use of abemaciclib for 2 years or ribociclib for 3 years; addition of palbociclib for 2 years did not improve outcomes. Those with HER2-negative germline BRCA-mutated breast cancer who have received (neo)adjuvant chemotherapy should consider a year of oral olaparib. When used in conjunction with chemotherapy or anti-HER2 therapy, endocrine therapy is generally delayed until completion of adjuvant chemotherapy to minimize toxicity. PART 4 Oncology and Hematology Approach to HER2-Positive Breast Cancer  Healthy individuals with tumor ≥3 cm or positive lymph nodes are candidates for neo­ adjuvant therapy with multiagent chemotherapy and trastuzumab with or without pertuzumab for 4–5 months. Those who achieve a pCR should receive further trastuzumab with or without pertu­ zumab therapy to complete a year. By contrast, those with residual invasive disease at surgery should switch to complete a year of the antibody-drug conjugate (ADC) trastuzumab emtansine (TDM-1). High-risk individuals who have completed a year of anti-HER2 therapy can also consider addition of oral neratinib for another year, although the benefits are incremental. Toxicity of trastuzumab is relatively uncommon. Few patients have any side effects during treatment. However, the greatest risk is reduction of cardiac ejection fraction. Therefore, baseline cardiac evaluation with an echocardiogram should be obtained, and trastu­ zumab should not be given to those with low ejection fraction, or they should be evaluated by an experienced cardiologist if therapy is felt to be critical. Serial echocardiograms should be obtained during adjuvant trastuzumab therapy but are not indicated once therapy is discontinued if the patient has not had any evidence of cardiac dysfunction. Pertuzumab is commonly associated with loose stools or diar­ rhea. This can be managed with conservative loperamide treatment. However, the added benefit of adjuvant pertuzumab to trastuzumab is modest, and if diarrhea is not easily controlled, trastuzumab should be continued alone. Individuals who present with smaller tumors with clinically neg­ ative nodes should be considered for upfront surgery to establish pathologic stage. This is because women with pathologically nodenegative tumors <3 cm have excellent outcomes with a regimen of single-agent weekly paclitaxel for 12 weeks in conjunction with a year of trastuzumab with or without pertuzumab. Patients with HER2-positive tumors that are ER and/or PR posi­ tive should receive endocrine therapy as described above. Endocrine therapy is generally initiated after completion of any chemotherapy and can be given concurrent with anti-HER2 therapy. Neither CDK4/6 inhibitors nor PARP inhibitors have been tested as an adju­ vant therapy in early-stage HER2-positive breast cancer. Triple-Negative Breast Cancer (TNBC)  Healthy patients with early-stage TNBC are frequently candidates for (neo)adjuvant che­ motherapy. Those with tumors >2 cm or tumors >1 cm and positive axillary nodes should be considered for neoadjuvant multiagent chemotherapy, perhaps in conjunction with the checkpoint inhibi­ tor pembrolizumab. If chemoimmunotherapy is utilized, then pem­ brolizumab is continued postoperatively to complete a year. Those who achieve a pCR receive pembrolizumab alone. Those patients who do not have a pCR may also consider further chemotherapy with capecitabine. In contrast, those with smaller tumors that are clinically node negative are best served by initial surgery to estab­ lish pathologic stage, which might permit a refinement of choice of chemotherapy regimen. Follow-Up of Survivors of Early-Stage Breast Cancer  Asymp­ tomatic survivors of early-stage breast cancer should be followed regularly with history and physical examination to look for any evidence of recurrent disease and to assess for toxicities of prior or ongoing treatments. These exams are conducted every 3–6 months for the first 3 years and diminish in frequency over time. As noted, serial echocardiograms beyond 12 months of trastuzumab therapy are not needed. Annual breast imaging to look for ipsilateral or contralateral disease is the only routine testing needed. In the absence of symptoms or physical exam findings, routine imaging of other types or blood studies have not been shown to enhance wellbeing or outcome from breast cancer. Current research is focused on use of blood-based assays for circulating tumor cells (CTCs) or circulating free tumor DNA (ctDNA) as markers for early detection of recurrent disease, but these are investigational approaches at present. As many patients have long survival, routine follow-up by a primary care provider and adherence to age-appropriate general health guidelines are key. Symptom management is a key aspect of follow-up, especially for those on adjuvant endocrine therapy as adherence is a crucial determinant of outcome. Hot flashes may be ameliorated by use of antidepressants like venlafaxine or gabapentin, while vaginal dry­ ness should be addressed through topical agents or, if unsuccessful, vaginal estrogen. Avoidance of hormone replacement therapy is preferred. Aromatase inhibitor–associated musculoskeletal symp­ toms may be treated by switching from one aromatase inhibitor to another after a 4- to 6-week washout period, or they can be addressed by exercise, nonsteroidal anti-inflammatory agents, acu­ puncture, or the antidepressant duloxetine. Persistent taxane-related peripheral neuropathy is sometimes responsive to gabapentin. Special Considerations in Management of Individuals with Early Breast Cancer  Use of Bisphosphonates  Bone health can be compromised by breast cancer therapy, especially the estrogen-deprivation agents, aromatase inhibitors and LHRH agonists. Patients who receive these therapies may benefit from use of a bisphosphonate, zoledro­ nate every 6 months for 3 years, or oral clodronate or ibandronate as a bone-strengthening agent. In addition, a meta-analysis suggests that this therapy is associated with decreased breast cancer recur­ rence, especially in bone. Data on denosumab are less compelling at present. Pregnancy, Fertility, and Childbearing in Premenopausal Women  The diagnosis of breast cancer during pregnancy can be difficult because of the evolving changes in the pregnant breast. Suspicious lumps or skin or nipple changes should be evaluated as above though imaging modalities of choice including ultrasound or MRI. If breast cancer is diagnosed and pregnancy is continued, the goal is to administer appropriate multimodality therapy to optimize maternal outcome from breast cancer and minimize toxicity to the fetus. Breast surgery can be safely undertaken during the second and third trimesters, but any therapeutic radiation must be delayed until after delivery. If indicated, certain chemotherapy agents such as doxorubicin and cyclophosphamide can be administered during the second and third trimesters, whereas others such as methotrex­ ate and 5-fluorouracil should be avoided. In general, endocrine and targeted therapies should not be used until after delivery. Comanagement by experienced multidisciplinary breast cancer and high-risk obstetrical teams is preferred. Diagnosis of breast cancer in all premenopausal women neces­ sitates discussion about fertility preservation and pregnancy with those women who desire later pregnancy. Premature menopause is a known consequence of adjuvant chemotherapy, and likeli­ hood is related to type and duration of chemotherapy and age of patient. It is seen in <50% of women <40 years old but is common in those who are over 40. Patients are asked to avoid pregnancy while on adjuvant endocrine therapy. Thus, counseling about and implementation of fertility-preservation techniques are a priority in newly diagnosed premenopausal women if further childbearing is planned. A meta-analysis suggests that concurrent administration of an LHRH agonist to suppress ovarian function during adjuvant chemotherapy may help to preserve subsequent ovarian func­ tion without adverse breast cancer outcomes. Avoidance of oral contraceptives or hormone-based intrauterine devices is recom­ mended for premenopausal breast cancer survivors who require contraception. Though data are not extensive, pregnancy after early stage breast cancer diagnosis appears to be safe. There is no evidence of increased rate of recurrence compared to matched patients who did not become pregnant, nor is there evidence of increased fetal anom­ alies. A recent study has documented the safety and pregnancy success rate for women with treated early ER-positive breast cancer who stop adjuvant tamoxifen after 18–24 months of therapy and then resume after pregnancy to complete their prescribed course. Male Breast Cancer  Men with breast cancer usually present with a breast lump or other physical abnormality. Principles about diagnosis, staging, and local therapy are like those for women, although most men undergo mastectomy for primary management for anatomic reasons. Men with breast cancer should undergo genetic testing as germline BRCA mutation is seen in up to 14% of men with breast cancer. About 90% of male breast cancers express ER, and adjuvant endocrine therapy is standard. Tamoxifen is the drug of choice; if an aromatase inhibitor is indicated (as for example in an individual who has a history of thromboembolic disease), concomitant administration of an LHRH agonist is required. Guidelines for use of adjuvant chemotherapy are like those for postmenopausal women. LOCALLY ADVANCED BREAST CANCER In the United States, about 10% of patients present with locally advanced or stage III breast cancers, although this presentation is more common in less-resourced countries. These tumors are characterized by a large primary tumor, involvement of skin or chest wall, or fixed tumors or axillary lymph nodes, findings that make primary surgical resection difficult or impossible. Inflam­ matory tumors that present with rapid onset of erythema, swelling, and tenderness of the breast are a subset of locally advanced breast cancer and are sometimes confused with mastitis or other infection. Breast or skin biopsy is critical in the setting of breast inflammation that fails to resolve after antibiotics. Skin biopsy showing dermal lymphatic invasion with tumor cells is often associated with the diagnosis of inflammatory breast cancer. Because up to one-third of these patients have detectable metastasis at time of diagnosis, an evaluation for metastatic disease is recommended even in asymp­ tomatic patients. Combined-modality therapy begins with neoadjuvant systemic therapy, whose selection is guided by biomarker status as outlined above, to downstage tumor to permit resection. Mastectomy with axillary dissection is often required in the case of inflammatory or other T4 lesions because breast-conserving therapy has been associ­ ated with an unacceptably high incidence of locoregional recurrence. Postoperative radiotherapy is the norm in conjunction with systemic therapy with chemotherapy and/or anti-HER2 therapy and/or endo­ crine therapy tailored to the biological qualities of the tumor. METASTATIC BREAST CANCER Presentation and Evaluation  About 20–25% of patients who are treated for early breast cancer subsequently develop metastatic disease, presumably because of micrometastatic disease at time of diagnosis that was or becomes resistant to adjuvant systemic therapy. Metastatic disease can be detected years to decades after primary diagnosis, especially in the setting of ER-positive disease, whereas it is most likely to be diagnosed within 3–7 years after treatment for TNBC or ER-negative/HER2-positive breast cancer. Only about 5% of patients present with de novo metastatic or stage IV breast cancer in the United States. Patients may present with abnormal physical exam or symptoms suggestive of metastases. As shown in Fig. 84-3, careful evaluation of extent of disease with computed tomography and radionuclide imaging, routine blood studies, and measurement of tumor mark­ ers such as carcinoembryonic antigen (CEA) and either CA27/29 or CA15-3 should be undertaken. Wherever possible, it is critical to biopsy a suspicious lesion to confirm the diagnosis of metastatic breast cancer and assay tumor markers including ER, PR, and HER2 because they may have changed from the initial biopsy under the pressure of time or therapy. In addition, PD-L1 staining and tumor mutational burden should be assessed in tumor, and assays for PIKC3A and ESR1 mutations should be performed in blood or tumor to delineate options for treatment. Next-generation sequenc­ ing of tumor may also be considered to simultaneously survey for any other targetable changes to guide selection of therapy or eligi­ bility for a clinical trial. CHAPTER 84 Goals of Care and General Management  Metastatic breast cancer is rarely curable, and the goals of therapy, which is chronic—to palliate or prevent symptoms without undue toxicity—should be explicitly discussed with the patient at the time of diagnosis of metastatic disease. Median survival is <3 years, although the range is wide. Some patients with favorable characteristics such as ERpositive disease, nonvisceral disease, long disease-free interval, and good performance status may survive using serial therapies for many years, whereas those with TNBC are more likely to progress sooner and succumb to their disease. Advances in our understand­ ing of biology of ER- and HER2-positive and genetically mutated (e.g., BRCA1/2, PIK3CA) breast cancer and development of a myriad of targeted treatments have led to improved outcome for these subtypes in recent years. Breast Cancer Unlike in early breast cancer, the primary intervention in meta­ static breast cancer is systemic therapy. Surgery is generally limited to excision of isolated local recurrence or a solitary brain metastasis or stabilization of a bone metastasis. Randomized trials suggest that patients who present with de novo metastatic breast cancer do not have improved outcomes with surgical treatment for the primary breast cancer in addition to systemic therapy and the focus should be on systemic therapy. Radiotherapy may be used at any time to palli­ ate symptomatic localized disease such as bony or brain metastases. All patients with metastatic breast cancer should have access to palliative therapy approaches in addition to antineoplastic therapy to maximize symptom control and quality of life. In addition, those with metastatic bone disease should be considered for regular administration of bisphosphonate or denosumab in addition to antineoplastic therapy to reduce the chance of skeletal morbidity including pain, fracture, and need for radiotherapy. Patients with metastatic breast cancer require regular followup with history and physical exam to gauge response to therapy. Patient well-being and relief of symptoms are paramount, and use of imaging and blood studies should be personalized to the patient and therapy to adjust dose or schedule and to assist in decisions about efficacy and toxicity of therapy. Current algorithms suggest changes in therapy only if the patient has clear signs of disease progression or unacceptable toxicity. Studies to evaluate the role of serial liquid biopsies to track CTC or ctDNA as an indicator to switch therapy, and even to switch to a targeted therapy suggested by the mutational profile of the ctDNA, in the absence of clinical or radiologic evidence of disease progression are in progress. Management of ER-Positive Metastatic Breast Cancer  Whenever possible, serial use of endocrine therapy is the preferred approach Clinical symptom History, physical exam Suspicious history or clinical finding Diagnostic workup Imaging as indicated (direct image of suspicious site; anatomic imaging: CT or MRI; scintigraphic imaging: bone or PET scan) blood tests as indicated (CBC, liver function tests, circulating tumor biomarkers: CA15-3 or 27.29; CEA) Confirmed suspicious finding Nondiagnostic Follow-up evaluation Biospy if possible PART 4 Oncology and Hematology Resolved Uncertain or persists Routine follow-up Routine follow-up Continue follow-up rule out noncancer etiology repeat diagnostic workup if indicated FIGURE 84-3  Evaluation of new signs or symptoms in a patient with prior history of early-stage breast cancer. See text for details. CBC, complete blood count; CEA, carcinoembryonic antigen; ER, estrogen receptor; NGS, next-generation sequencing; PET, positron emission tomography; PgR, progesterone receptor. to patients whose recurrent tumor is ER and/or PR positive and whose clinical presentation is not dire. Use of chemotherapy can be reserved for those with life-threatening visceral disease like lymphangitic lung metastases or impending liver failure. However, a prospective trial has suggested that overall survival was the same in patients with apparent rapidly growing visceral disease ran­ domly assigned to either chemotherapy or endocrine therapy and a CDK4/6 inhibitor. There is no value for concurrent endocrine therapy and chemotherapy for management of metastatic breast cancer. Selection of type of endocrine therapy will depend on menopausal status and previous adjuvant endocrine therapy. It may be paired with targeted therapy depending on the molecular profile of the cancer and clinical scenario. For the uncommon patient who presents with untreated ER-posi­ tive metastatic breast cancer, therapy generally begins with aromatase inhibitor plus CDK4/6 inhibitor for postmenopausal women and LHRH agonist plus aromatase inhibitor plus CDK4/6 inhibitor for premenopausal women; median progression-free survival is about 2 years, and median overall survival is >3 years with this approach. More commonly, patients present with recurrent disease diag­ nosed while on or after completing adjuvant endocrine therapy. For those who have received aromatase inhibitor, up to one-half will have evidence of ESR1 mutation and may be candidates for the oral selec­ tive estrogen receptor degrading (SERD) agent elacestrant if they have also received a CDK4/6 inhibitor. Those without evidence of ESR1 mutation are often treated with an alternate SERD, fulvestrant, which is administered monthly by intramuscular injection; this may be coupled with a CDK4/6 inhibitor if the patient has not previously received such an agent. The value of continuing or switching to another CDK4/6 inhibitor for those who have previously received adjuvant CDK4/6 inhibitor is not clearly defined in this setting. For postmenopausal patients previously treated with endocrine therapy who are found to have a PIKC3A mutation by liquid or tissue biopsy, the use of alpelisib (a selective inhibitor of PI3Kα) with fulvestrant can be considered. Postmenopausal patients with Other cancer or condition Positive for metastases Benign Further evaluation and treatment as indicated Re-evaluate tumor biomarker status ER, PgR, HER2, PIK3CA mutation, PD-L1, NGS (tissue or circulating) PIK3CA/AKT1/PTEN alterations who have received one endocrine therapy for metastatic disease or recur within 12 months of complet­ ing adjuvant therapy can receive capivasertib (a pan-AKT inhibitor) with fulvestrant. The use of aromatase inhibitor plus everolimus, an mTOR inhibitor, can be considered for patients without targetable mutations as it, too, has been shown to increase progression-free survival over endocrine therapy alone. Each of these targeted agents carries a unique set of toxicities, and careful monitoring of clinical status and blood studies is needed for safe administration. Other approaches, especially for patients who have demonstrated repeated and lengthy responses to serial hormone therapies, can include switch to another aromatase inhibitor or tamoxifen or administration of additive hormone therapies such as progestins, androgens, and estrogens. The latter category of agents is seldom used at present because of concerns about toxicity and the advent of newer more targeted therapies. At some point, it will become apparent that a patient has tumor that is unresponsive to endocrine therapy, which necessitates a transition to other types of systemic therapy. The timing of this decision may be informed in part by the observation that likelihood of disease control and the duration of benefit are decreased by about one-half with each successive switch in endocrine therapy. Management of Endocrine-Unresponsive ER-Positive, HER2-Negative Breast Cancer or TNBC  Chemotherapy is the backbone of sys­ temic therapy for individuals with metastatic HER2-negative breast cancer that is not responsive to endocrine therapy. Unlike in the setting of early breast cancer where multiagent chemotherapy is the norm, use of combination chemotherapy in metastatic breast cancer should be reserved for the uncommon situation of visceral crisis where a rapid reduction in tumor burden is desirable. For most patients, serial use of single-agent chemotherapy is associated with an acceptable likelihood of disease palliation without excess toxic­ ity; combination chemotherapy does not improve overall survival over sequential monotherapy. # 14 - 85 Upper Gastrointestinal Tract Cancers ### 85 Upper Gastrointestinal Tract Cancers Many chemotherapeutic agents are active in metastatic breast cancer, and selection is based on previous adjuvant chemotherapy and patient preference about route and schedule of administration and side effects. The oral agent capecitabine is often used initially because of ease of administration and acceptable side effect profile. However, several studies have demonstrated that a small percent­ age of the population harbors deleterious mutations in the DPYD gene, which is responsible for converting capecitabine to its inac­ tive metabolites for excretion. Such patients are prone to suffering extreme and, in some cases, lethal toxicities, and some guidelines call for routine testing for this gene before initiating capecitabine or other fluoropyrimidines, such as 5-fluorouracil. Other options include taxanes, anthracycline (depending on previous adjuvant exposure), vinorelbine, gemcitabine, cyclophosphamide, metho­ trexate, eribulin, ixabepilone, and platinum-based agents; the last is often considered in TNBC because of evidence of activity of platinums in that subtype. For patients with TNBC that expresses PD-L1, administration of paclitaxel with the checkpoint inhibitor pembrolizumab can be considered because the combination results in better outcomes than taxane alone; activity of other checkpoint inhibitors is under investigation. ADCs are increasingly finding a role in treatment of metastatic breast cancer. Sacituzumab govitecan, an antibody targeted against TROP-2SN-38 coupled to an irinotecan metabolite, has shown activity against TNBC and endocrine-unresponsive ER-positive, HER2-negative breast cancer. A second ADC, trastuzumab derux­ tecan, which couples trastuzumab with the cytotoxic deruxtecan (discussed in greater detail below in the HER2 section) is also active against tumors that express low levels of HER2 (1+ or 2+/fluorescence in situ hybridization [FISH] negative) and were initially labeled HER2 negative and thus ineligible for adjuvant anti-HER2 therapy using other anti-HER2 agents. Development and testing of novel ADCs are very vibrant areas in treatment of metastatic breast can­ cer, and findings are beginning to challenge some of our concepts about targeted therapy. For patients whose tumors have evidence of germline or somatic BRCA mutation, use of single-agent PARP inhibitor with olaparib or taloparib should also be considered, perhaps before the transi­ tion to infusional therapies because of convenience. Management of HER2-Positive Breast Cancer  The landscape of treatment for metastatic breast cancer has changed substantially in the 25 years since the importance of HER2 protein expression as a predictor for response to anti-HER2 therapy was demonstrated. FDA-approved HER2-directed therapies now include monoclo­ nal antibodies (trastuzumab, pertuzumab, margetuximab), smallmolecule tyrosine kinase inhibitors (lapatinib, neratinib, tucatinib), and ADCs (ado-trastuzumab emtansine or TDM-1, trastuzumabderuxtecan), and others are under development. Apart from trastuzumab-deruxtecan, their clinical benefit is seen only in indi­ viduals whose tumors express 3+ HER2 staining by immunohisto­ chemistry or are gene-amplified by FISH. The preferred first-line treatment for metastatic HER2-positive breast cancer is a combination of taxane, pertuzumab, and trastu­ zumab for several months; taxane chemotherapy may be stopped when disease stability is reached, and the anti-HER2 agents are continued as maintenance therapy. In some cases, this approach can lead to long-term remission, and an active area of research is how long to continue anti-HER2 therapy for those with complete response. A randomized clinical trial has established the superior­ ity of trastuzumab-deruxtecan for second-line therapy. Thereafter, serial administration of anti-HER2 agents, in some cases in com­ bination with single-agent chemotherapy, is pursued. Patients who have HER2-positive, ER- and/or PR-positive breast cancer may benefit from concomitant endocrine therapy as well. HER2-positive breast cancers have a propensity for involvement of the central nervous system. Because control of systemic disease with anti-HER2 therapies can be excellent and penetration of the antibody-based agents across the blood-brain barrier is poor, patients with this disease subtype are often found to have brain metastasis and may require radiotherapy for local disease control. The small-molecule inhibitors may also offer disease control as they cross into the central nervous system. ■ ■FURTHER READING Andre F et al: Biomarkers for adjuvant endocrine and chemotherapy in early-stage breast cancer: ASCO Guideline Update. J Clin Oncol 40:1816, 2022. Bedrosian I et al: Germline testing in patients with breast cancer: ASCO-Society of Surgical Oncology guideline. J Clin Oncol 42:584, 2024. Benitez Fuentes JD et al: Global stage distribution of breast cancer at diagnosis: A systemic review and meta-analysis. JAMA Oncol 10:71, 2024. Burstein HJ: Systemic therapy for estrogen receptor-positive, HER-2 negative breast cancer. N Engl J Med 383:2557, 2020. Curigliano G et al: Understanding breast cancer complexity to improve patient outcomes: The St Gallen International Consensus Conference for the Primary Therapy of Individuals with Early Breast Cancer 2023. Ann Oncol 34:970, 2023. Giordano S et al: Systemic therapy for advanced human epidermal CHAPTER 85 growth factor receptor 2-positive breast cancer: ASCO guideline update. J Clin Oncol 40:2636, 2022. Henry NL et al: Biomarkers for systemic therapy in metastatic breast cancer: ASCO guideline update. J Clin Oncol 40:3205, 2022. Jackson EB, Chia SKL: Sequencing of endocrine therapy targeted ther­ apies in hormone-sensitive, human epidermal growth factor receptor 2-negative advanced breast cancer. J Clin Oncol 41:3976, 2023. Loibl S et al: Breast cancer. Lancet 397:1750, 2021. Nielsen S, Narayan AK: Breast cancer screening modalities, recom­ Upper Gastrointestinal Tract Cancers mendations, and novel imaging techniques. Surg Clin North Am 103:63, 2023. PDQ Screening and Prevention Editorial Board: Breast Cancer Prevention (PDQR). https://www.ncbi.nlm.nih.gov/books/ NBK65884/.  Accessed January 7, 2024. David Kelsen Upper Gastrointestinal Tract Cancers Cancers of the upper gastrointestinal tract include malignancies of the esophagus, stomach, and small bowel. Esophageal, gastroesophageal junction (GEJ), and gastric cancers are among the most common of human malignancies, with 1.693 million global new cases diagnosed in 2020; as a measure of the gravity of such a diagnosis, there were an estimated 1.312 million deaths. In the United States, a lower-risk area, it is estimated that in 2023, esophageal cancer will be diagnosed in 21,560 people and cause 16,120 deaths; for gastric cancer, 26,500 new cases will be diagnosed and 11,130 deaths will occur. Small intestine cancers are rare. ESOPHAGEAL CANCER ■ ■GLOBAL DIFFERENCES IN INCIDENCE AND CAUSATIVE FACTORS Two distinct forms of cancer with different epidemiologies, causative factors, and genomic profiles arise within the esophagus: squamous cell cancers (SCCs), which occur more frequent in the upper and mid esophagus; and adenocarcinomas, which are almost always located in the lower esophagus and at the GEJ. The incidence of esophageal cancer varies up to 20-fold in global geographic distribution: it is relatively uncommon in North America but has a high incidence in Asia (especially China), the Normandy coast of France, and Middle Eastern countries such as Iran. This marked global variation is likely due to different causative factors in the development of the malignancy, leading to two different cancer types within the same organ: glob­ ally, SCCs make up the majority of cases, as they are more common in high-incidence areas, usually with lower of the four-tier Human Development Index (HDI) scores (a measure of economic develop­ ment that includes standard of living, health, and education). Overall, approximately 604,100 new cases of esophageal cancer were diagnosed globally in 2020; esophageal cancer was the tenth most common cause of malignancy and the sixth most common cause of cancer-related mortality, with an estimated 544,076 deaths. The most established high-risk factors for the SCC subtype in Western countries are alcohol or tobacco abuse; concurrent alcohol and tobacco abuse further increases the risk. Ingestion of extremely hot sub­ stances (such as tea in Iran and mate [maté] in South America) has been proposed as a risk factor; in India, chewing the areca (betel) nut increases the risk of esophageal SCC. Less common risk factors include chronic achalasia, radiation therapy (such as is delivered for treatment of Hodg­ kin’s lymphoma or breast cancer), lye ingestion, and Plummer-Vinson (Patterson-Kelly) syndrome (iron deficiency anemia, glossitis, cheilosis, and the development of esophageal webs). Adenocarcinoma of the lower esophagus and GEJ has been the predominant histologic subtype in the United States and Western Europe for several decades, now making up >75% of all incident cases. Risk factors for adenocarcinoma include chronic reflux esophagitis leading to inflammation and the development of Barrett’s esophagus (the finding of glandular gastric type mucosa extending into the esophagus). Although obesity increases the risk of reflux esophagitis, a substantial number of patients with newly diag­ nosed adenocarcinoma of the esophagus and GEJ are younger and fit; Barrett’s esophagus may still be found in these patients. In patients with adenocarcinoma of the lower esophagus in which Barrett’s esophagus is not present, the disease may arise without Barrett’s esophagus, or an exten­ sive tumor found at diagnosis may obliterate previous areas of Barrett’s. Genomic alterations may be identified even before the development of frank adenocarcinoma in patients with dysplasia associated with Barrett’s esophagus. These include mutations of TP53, a gene critical in regulating uncontrolled cell division, and aneuploidy in dysplastic regions. Risk of progression of Barrett’s esophagus to cancer is about 0.4–0.5% per year. Management of Barrett’s esophagus is discussed in Chap. 334. PART 4 Oncology and Hematology As opposed to other gastrointestinal malignancies, such as colorec­ tal cancer, inherited cancer susceptibility genes are rarely associated with esophagus and GEJ cancers. An exception is the rare inherited cancer susceptibility gene driving tylosis palmaris and plantaris; a mutation in the RHBDF2 gene is associated with an increased risk for SCC of the esophagus. Both Lynch syndrome and germline BRCA mutation carriers have a modestly increased risk of gastric and poten­ tially GEJ adenocarcinomas. Identification of these germline mutations is important because it guides choices of systemic therapy, as well as counseling of family relatives (see below). ■ ■SCREENING AND SURVEILLANCE OF HIGHER RISK GROUPS Because of its low incidence in North America and the absence of proven blood-based biomarkers for esophageal cancer assays, screen­ ing of the asymptomatic general population using, e.g., upper endos­ copy is not currently recommended in the United States. Periodic endoscopy is used for surveillance of higher risk patients, such as those with Barrett’s esophagus, especially with dysplasia, based on expert opinion guidelines. Early-Onset GEJ and Gastric Cancers  A marked increase in the incidence of early-onset gastrointestinal malignancies (EOGI; cancer occurring in people <50 years of age) has been noted over the past several decades. First noted were early-onset colorectal cancers, occurring particularly in the left-sided colon or rectum; the start of the steep increase was traced back to the mid-1990s. A similar trend has been noted in upper gastrointestinal tract cancers, particularly in women. The large majority of EOGI patients do not have inherited germline cancer susceptibility gene mutations or a family history of malignancy for colon cancer or small-bowel cancer or inflammatory bowel disease. Driving factors suggested for the steep increase include lifestyle changes such as being more sedentary (less exercise), dietary changes leading to obesity, use of alcohol and tobacco, changes in the microbiome, and exposure to an as not yet identified environmental agent, not previously used, which was introduced to the general popu­ lation in the 1980s or 1990s. Because the absolute number of young people developing GEJ or gastric cancers is still small, surveillance upper endoscopy or imaging is not recommended (for colon cancer screening, current U.S. recommendations are to start at age 45 years). Efforts are underway to develop sensitive and specific early detection biomarkers such as blood-based assays. Because these cancers are uncommon in young patients, symptoms may be attributed to benign illnesses so that advanced stages are common at the time of diagnosis. Physicians should be aware that symptoms in a young person found more typically in older patients, such as dysphagia, odynophagia, or upper abdominal discomfort, may be related to malignancy, leading to the same diagnostic studies as performed in older patients. ■ ■GENOMIC ALTERATIONS Genomic alteration analyses have revealed substantial genomic dif­ ferences between adenocarcinomas and SCCs of the esophagus. The well-known integrated analysis involving several different genomic platforms, performed by The Cancer Genome Atlas (TCGA) Research Network investigators, demonstrated that esophageal SCC more closely resembled SCCs of other primary sites, such as the head and neck, than adenocarcinomas arising in the esophagus. Three molecu­ lar subclasses of SCC were identified (of note, as opposed to SCC of the head and neck, human papillomavirus was not identified in any of the three subgroups). Similarly, a study of 528 Chinese SCC patients, using whole genome sequencing, evaluated structural variations resulting in rearrangements; five types of structural variations were identified, and some of these may be of clinical significance. In adeno­ carcinomas, HER2/ERBB2 is frequently amplified, and microsatellite instability can be found in both esophageal and GEJ adenocarcinomas. Epstein-Barr virus (EBV) infection is a driver in adenocarcinoma. The similar genomic profile for adenocarcinomas of the distal esophagus, GEJ, and cardia of the stomach suggests that proximal gastric and GEJ tumors may have a similar driving factor (see below). A genomewide association study identified 27 risk loci for the development of adenocarcinomas of the esophagus or GEJ, with a difference between adenocarcinoma arising in Barrett’s esophagus versus not. Other stud­ ies comparing transcriptomes of adenocarcinomas and SCC across organs (i.e., the same tumor histology arising in different organs, such as SCCs and adenocarcinomas from the esophagus, lung, and uterine cervix) found that the same histologies among the different organs showed more similarity than between the different histologies within the same organ. In addition to implications regarding driving factors in the initiation and progression of cancer, these genomic alterations are important for therapeutic decisions involving systemic agents given in the neoadjuvant or postoperative adjuvant setting or for advanced metastatic disease. For esophageal adenocarcinoma, genomic abnor­ malities that should be considered in prescribing drug-based therapy include analysis for HER2/ERBB2 amplification, programed death ligand 1 (PD-L1) expression, and hypermutated tumors/microsatellite instability (see Table 85-1, and below). For SCC of the esophagus, the degree of PD-L1 expression may be of importance. CLINICAL FEATURES ■ ■PRESENTING SYMPTOMS The most common symptoms leading to suspicion of esophageal can­ cer are dysphagia or odynophagia and, less frequently, hematemesis or melena. More subtle symptoms include anorexia and weight loss, and TABLE 85-1  AJCC Prognostic Stage Groups for Esophageal Cancer Using cTNM (Pretreatment)a TNM CLINICAL STAGE PRESENTING AT THIS STAGEb,c SQUAMOUS ADENOCARCINOMA cTis, N0, M0 1.2% 75% 82% cT1-2, N0, M0 I 17% 75% 78% cT1-2, N1-3, M0 IIA 7% 53% 50% cT3-4a, N0, M0 IIB 13% 40% 40% cT3-4a, N1-3, M0c III 31% 25% 25% cT4b, any N, M0 IVA 17% 21% cAny T, any N, M1 IVB 5% 10% 18% Survival by ypTNM Staging After Neoadjuvant Chemotherapy ESTIMATED 5-YEAR SURVIVAL RATE TNM yp STAGE SQUAMOUS ADENOCARCINOMA T1-2, N0, M0 T1, N1, M0 I 46% 52% T3, N0-1, M0 T2, N1-2 M0 T1, N2-3, M0 T4a, N0, M0 II 34% 38% T4a, N1-3 M0 T4b, any N, M0 T3, N2-3, M0 T2, N3, M0 III 22% 27% Any T, any N, M1 IV 10% 12% aAJCC Cancer Staging Manual Version 9 expected in 2024. bSquamous cell and adenocarcinoma histologies combined. CSurgical series; underestimates incidence of M1 disease at presentation. dIncidence includes cT4b and cNanyMO. Sources: Adapted from TW Rice et al: CA Cancer J Clin 67:304, 2017; TW Rice et al: Dis Esophagus 29:707, 2016; and TW Rice et al: personal communication. fatigue and shortness of breath if anemia from gastrointestinal bleed­ ing is present. Because the symptoms of dysphagia or odynophagia are usually not perceived by the patient until substantial obstruction of the esophageal lumen has occurred, the large majority of patients with esophageal cancer are found with locally advanced if not metastatic dis­ ease. Patients with symptoms of dysphagia and/or odynophagia should undergo upper endoscopy to determine the presence or absence of malignancy; biopsy should be performed at the same setting to deter­ mine histology. Depending on the tumor stage, molecular diagnostic or next-generation sequencing (NGS) analysis to assist in determining potential therapies should be performed. PD-LI, which may guide use of immune modulation therapy, is assessed by immunohistochemistry (IHC). NGS requires adequate tumor cellularity, which may be difficult to achieve from endoscopic biopsy. NGS is currently probably the most efficient methodology for genomic analysis (other than PD-L1), and genomic analysis should be done on all patients with metastatic disease because it will guide therapy. Some high-volume U.S. centers routinely perform NGS on all specimens, including from all but the most earlystage primary tumors of patients without metastatic disease. ■ ■STAGING Therapeutic strategy is currently based on the stage of the disease using a system such as the eighth version of the American Joint Committee on Cancer (AJCC) Staging Manual (for esophageal and gastric cancers, the ninth version is expected in 2024) tumor-node-metastasis (TNM) staging system. The T stage is based on the size of the tumor and depth of penetration through the esophageal wall (which for most of its course is not covered by serosa so that invasion through the muscle layer leads directly into periesophageal tissues) (Fig. 85-1). Patients with regional lymph node metastases are still potentially curable. Meta­ static disease is generally treated with palliative intent with rare excep­ tions. Because neoadjuvant (preoperative) therapy is widely employed for esophageal cancer to improve subsequent surgical outcomes, the AJCC TNM staging system includes clinical, pathologic (for patients 5-YEAR SURVIVAL RATE CHAPTER 85 Upper Gastrointestinal Tract Cancers undergoing initial surgery as first treatment), and ypTNM staging assessment for those treated with preoperative therapy. See Table 85-2 for the TNM staging classification for gastric cancer, which is similar to esophageal cancer. Determining tumor extent includes careful physical examination, which may reveal palpable lymphadenopathy or hepatomegaly; imag­ ing studies including computed tomography (CT) and fluorodeoxyglu­ cose (FDG) positron emission tomography (PET)-CT scan are used to assess for metastatic disease. If no metastatic disease is identified, endoscopic ultrasonography (EUS) is commonly performed to more definitively determine depth of penetration of the primary tumor (T) and regional lymph node involvement. Deep learning artificial intel­ ligence methodology may assist the imaging analysis to improve the diagnostic sensitivity and specificity of EUS for both esophageal and gastric cancers. For tumors of the mid and upper esophagus (5% of esophageal cancers are in the upper third of the esophagus, 20% in the middle third, and 75% in the lower third), bronchoscopy may be per­ formed to rule out invasion of the tracheobronchial tree. The finding of invasion of the trachea or bronchus rules out surgical intervention with curative intent. Regional lymph nodes may be biopsied under EUS guidance. For GEJ tumors, as for gastric cancers, laparoscopy is performed at many centers to assess for peritoneal involvement if the T stage is more advanced. If metastatic disease is suspected, biopsy to confirm tumor staging and to obtain adequate tissue for molecular and genomic alterations analysis should be performed. Assay of plasma ctDNA (circulating tumor DNA) can be used to detect genomic altera­ tions before treatment if biopsy tissue is too limited to allow NGS or molecular diagnostics; ctDNA is being studied as a measure of minimal residual disease after definitive regional therapy (surgery or chemora­ diation therapy). If systemic therapy is indicated as a portion of the treatment (for metastatic disease or for preoperative therapy for locally advanced cancers), serial FDG-PET/CT scans, using decrease in FDG avidity as a surrogate measure of effectiveness, are being used to guide whether the initial therapy should be continued or changed. Tis (HGD) T1a T1b T2 T3 T4a T4b NO N1 1 or 2 N2 3 to 6 N3 7 or more PART 4 Oncology and Hematology M1 Pleura FIGURE 85-1  Patterns of spread of esophageal cancer and the basis for anatomic staging. HGD, high-grade dysplasia. (Reproduced with permission from TW Rice et al: Cancer of the esophagus and esophagogastric junction: An eighth edition staging primer. J Thorac Oncol 12:36, 2017.) TREATMENT Esophageal Cancer Although the prognosis for patients with esophageal cancer (all stages) is still poor, a slow but steady improvement in 5-year survival has been noted. Because no cost-effective early detection methods exist in low-incidence countries, the number of U.S. patients found to have very-early-stage cancers at the time of diagnosis has not markedly increased; the modest improvement in survival is prob­ ably a combination of somewhat improved systemic therapy as well as decreased operative morbidity and mortality when surgery is performed by high-volume surgeons at high-volume centers, as well as improvements in the delivery of external-beam radiation therapy. For patients without evidence of metastatic disease, the goal of therapy is cure, usually by employing combined-modality therapies. Except for patients with early-stage esophageal cancer, who might be treated by surgery alone (or for very-early-stage lesions [Tis or T1a], by endoscopic mucosal resection [EMR] or submucosal dissection [ESD] for smaller [<2 cm] tumors); EMR and ESD are also used as part of initial staging to determine more definitively T stage), preoperative treatment including systemic drug therapy is a standard of care option for patients with esophageal and GEJ cancers. For locally advanced adenocarcinomas of the esophagus and GEJ, systemic therapy alone may be indicated: in the ESO­ PEC trial, preoperative systemic FLOT chemotherapy resulted in improved survival compared to preoperative chemoradiation (using the CROSS regimen). For selected patients with adenocar­ cinomas (e.g., not able to tolerate regimens such as FLOT), and for patients with SCC of the esophagus, chemoradiation remains a standard of care option; for SCC, chemoradiation may be definitive therapy. If surgery is planned after preoperative chemoradiation, a prolonged delay before surgery has been associated with a poorer outcome. For selected patients with GEJ adenocarcinomas, systemic Lamina propria Epithelium Basement membrane Submucosa Muscularis mucosae Muscularis propria Adventitia Aorta therapy alone may be given before definitive surgical resection. For patients with SCC of the upper and mid esophagus, combined chemotherapy plus concurrent radiation therapy is a standard option, with surgery reserved for patients not achieving a complete radiographic and endoscopic response. Radiation therapy alone is rarely given with curative intent, as chemotherapy plus concurrent radiation was superior to radiation therapy alone in several clinical trials. Increasingly, all systemic therapy with curative intent is given before operation, although if surgery is the initial therapy and the patient is found to have more locally advanced cancer at pathol­ ogy (e.g., regional lymph node metastasis), postoperative systemic therapy is used in the adjuvant setting. Adjuvant chemotherapy is more frequently indicated in patients with adenocarcinoma than SCCs. The CheckMate 577 trial demonstrated that for esophageal or GEJ cancer patients who received preoperative chemoradiation therapy and underwent a R0 (negative margins) resection but who had residual tumor in the resection specimen (i.e., not ypT0N0M0), postoperative adjuvant therapy with nivolumab, an immune-mod­ ulating agent targeting PD-1, significantly improved survival. For patients with metastatic disease, the goal of therapy is symptom palliation and life extension. No randomized trials of supportive care only versus systemic therapy plus best supportive care have been reported in patients with esophageal cancers. For gastric cancer (an adenocarcinoma histology, as are most distal esophageal and GEJ tumors), clinical trials performed in the 1980s and 1990s indicated a modest improvement in 1- and 2-year survival when systemic therapy plus best supportive care was used versus best supportive care only. While the cytotoxic chemotherapy regimens used for palliation have not changed dramatically over the past 10 years (currently including, for first-line treatment, a platinum compound such as oxaliplatin and a fluorinated pyrimidine such as fluorouracil or capecitabine; the FLOT [fluorouracil, leucovorin, oxaliplatin, and docetaxel] regimen includes docetaxel and is used TABLE 85-2  Staging System for Gastric Carcinomaa DATA FROM ACS IN THE UNITED STATES NO. OF CASES, % 5-YEAR SURVIVAL, % STAGE TNM FEATURES TisN0M0 Node negative; limited to mucosa IA T1N0M0 Node negative; invasion of lamina propria or submucosa IB T2N0M0 T1N1M0 Node negative; invasion of muscularis propria II T1N2M0 T2N1M0 Node positive; invasion beyond mucosa but within wall or T3N0M0 Node negative; extension through wall IIIA T2N2M0 T3N1-2M0 Node positive; invasion of muscularis propria or through wall IIIB T4N0-1M0 Node negative; adherence to surrounding tissue IIIC T4N2-3M0 >3 nodes positive; invasion of serosa or adjacent structures T3N3M0 7 or more positive nodes; penetrates wall without invading serosa or adjacent structures IV T4N2M0 Node positive; adherence to surrounding tissue or T1-4N0-2M1 Distant metastases aAJCC Cancer Staging Manual, Eighth Edition. Abbreviation: TNM, tumor-node-metastasis. in very fit patients), subgroups of patients have been identified who benefit from therapies targeting specific genomic alterations (Table 85-3). Approximately 20–25% of patients with adenocar­ cinoma of the esophagus or GEJ are found to have amplified or overexpressed HER2/ERBB2; trastuzumab plus chemotherapy, or trastuzumab, chemotherapy, plus immune therapy using pembro­ lizumab (for progression-free survival), results in higher response rates and longer progression-free and overall survival compared to chemotherapy alone. For patients whose tumors do not express HER2/ERBB2, immune-modulating therapy using PD-1 inhibi­ tors is a standard option as part of first-line therapy (in combina­ tion with chemotherapy) and as second-line palliative therapy for patients who have esophageal cancers expressing PD-L1. Patients TABLE 85-3  Molecular Diagnostics and Genomic Alteration Analyses Help Guide Systemic Therapy SITE HISTOLOGY FACTOR ASSAY TYPE THERAPY OPTIONS Esophageal SCC PD-L1 IHC Immunomodulation Esophageal Adeno/ GEJ PD-L1 IHC Immunomodulation Esophageal Adeno GEJ ERRB2/HER2 IHC/FISH/NGS Trastuzumab; trastuzumab-deruxtecan Esophageal Adeno GEJ/gastric dMMRP/MSI IHC/NGS Immunomodulation Gastric Adeno Claudin 18.2 IHC Zolbetuximaba aZolbetuximab is currently investigational. Abbreviations: Adeno, adenocarcinoma; dMMRP, deficient mismatch repair protein; FISH, fluorescent in situ hybridization; IHC, immunohistochemistry; MSI, microsatellite instability; NGS, next-generation sequencing; PD-LI, programmed death ligand 1; SCC, squamous cell carcinoma. whose tumors have high PD-L1 combined positive score (CPS) may have greater benefit. For patients with hypermutated or microsat­ ellite-unstable tumors, immune therapy alone is considered, using agents such as pembrolizumab, or nivolumab plus ipilimumab. As noted above, molecular diagnostic or NGS genomic alteration analysis assays to identify these biomarkers should be performed routinely in patients with metastatic esophageal, GEJ, and gastric cancer to help guide therapy. Supportive measures to improve nutrition and quality of life include placement of an endoluminal stent in the setting of highgrade obstruction; use of enteral nutrition can also be performed using a percutaneous gastrostomy. Photodynamic therapy and endoscopic laser therapy have been used to treat symptoms of endoluminal obstruction. TUMORS OF THE STOMACH ■ ■ADENOCARCINOMA OF THE STOMACH Incidence and Causative Factors  Since the 1920s, the incidence of gastric cancer has steadily decreased; while the reason for this has not been definitively identified, it coincided with widespread use of refrigeration and a decreased need for food preservatives. In 2023, it is estimated that there will be 27,500 new cases of gastric cancer diagnosed in the United States; while now seen much less frequently, it remains a lethal disease, with 11,130 deaths. As noted above, globally, gastric cancer is the third most common cause of cancer mortality. High-incidence areas, as is the case for esophageal cancers, include large Asian countries such as China, Korea, and Japan; South American countries such as Chile; and Eastern European countries. CHAPTER 85 Upper Gastrointestinal Tract Cancers While the number of new cases of body and distal gastric cancers has decreased in Western, high-tier HDI countries, the incidence of adenocarcinomas of the GEJ has markedly increased in the same areas over the past several decades, including as described earlier in younger patients. For gastric cancer overall, a higher incidence in some coun­ tries may be due to the ingestion of high concentrations of nitrates found in dried, smoked, and salted foods. Chronic inflammation, caused by an infection, is a major cause of gastric cancer. Helicobacter pylori infection is a known driver in many cases of gastric cancer. While H. pylori is extremely common, occurring in approximately half of all humans, gastric cancer occurs in only a small subset of those infected. Higher cancer risk has been associated with certain strains of H. pylori; while analyses of H. pylori are identifying high-risk genomic factors, a specific human genomic profile increasing risk of gastric cancer in the setting of H. pylori has not yet been identified. H. pylori and ingestion of partially decayed bacterially contaminated food may lead to the gen­ eration of carcinogenic nitrites from nitrates. Supportive evidence that H. pylori infection is a causative factor in the development of gastric cancer includes prospective studies demonstrating that treatment of H. pylori infection decreases the overall risk of gastric cancer. For exam­ ple, patients with H. pylori infection who had at least one first-degree relative with a history of gastric cancer (increasing their own risk of stomach cancer) were randomly assigned to placebo or treatment for H. pylori. The group receiving H. pylori eradication showed a signifi­ cant decrease in the incidence of gastric cancer (especially for those in whom H. pylori was successfully eradicated) compared to the control group. Earlier studies had demonstrated that treatment of H. pylori in Korean patients who had a prior very-early-stage gastric cancer decreased the incidence of a second gastric cancer. These data suggest that treat­ ment of asymptomatic H. pylori gastric infection should be considered for patients who have a first-degree relative who has had gastric cancer or who themselves have a prior history of an early-stage gastric cancer. The spectrum of the gastric microbiome beyond H. pylori may also be contributory to an increased risk of gastric cancer, with gastric cancer patients having a higher bacterial load than controls. EBV has also been associated with an increased risk for gastric cancer, and gastric cancer EBV phenotype and genotype have been well described. Another inflammation-driven cause is suspected to be reflux of gastric contents into the esophagus, particularly in obese people, increasing the risk of GEJ and esophageal adenocarcinomas. Obesity alone is not the cause, as a substantial number of GEJ patients are fit and not overweight. In addition to chronic inflammatory conditions, inherited cancer susceptibility genes increase the risk of gastric cancer. These include mutations of CDH1, which encodes for the cell cohesion gene e-cadherin; germline CDH1 mutations markedly increase the risk for the diffuse cell (signet cell) gastric cancer subtype (see below for discussion of histologic subtypes). Prophylactic gastrectomy as a risk-reducing sur­ gical procedure is an option for patients with an inherited deleterious CDH1 mutation. CDH1 mutations also increase the risk for lobular breast cancer. Germline mutations in the mismatch repair pathway (Lynch syndrome) and in the homologous repair pathway (BRCA mutations) slightly increase the risk for gastric cancer. Other inherited cancer susceptibility genetic syndromes that increase the risk of gastric cancer include familial adenomatous polyposis, juvenile polyposis, and Peutz-Jeghers syndrome. Surveillance programs for the early detec­ tion of gastric cancer for the higher risk germline cancer susceptibility genes (e.g., CDH1) should be employed. In addition, systemic therapy options for patients with certain germline mutations may be different from those with sporadic gastric cancer (e.g., for Lynch syndrome, immune modulation therapy; and for BRCA, use of DNA-damaging agents such as platinum compounds). Gastric cancer stem cells, mostly located in the isthmus of individual gastric glands and possibly originating in the bone marrow, may play an important role in the development of gastric cancer. H. pylori may be an inciting factor for recruitment of such bone marrow gastric stem cells. If this hypothesis is confirmed, it may have important implica­ tions for therapy of gastric cancers. PART 4 Oncology and Hematology Clinical Features  •  SURVEILLANCE STRATEGIES  As is the case for esophageal cancer, the incidence of gastric cancer in Western patients is relatively low, and early detection methodologies such as endoscopy are not routinely employed. The development of a “pan-cancer” bloodbased biomarker or a biomarker specific for gastric cancer would allow broader screening. At this time, the overwhelming majority of Western patients with gastric cancer are symptomatic at the time of diagnosis. Early detection programs in Japan and Korea, where gastric cancer has been among the most common of malignancies (although its incidence has been decreasing), include upper endoscopy; these programs have increased the number of patients found with early gastric cancer and Cardia GE junction CIN • Intestinal histology • TP53 mutation • RTK-RAS activation Pylorus Antrum GS • Diffuse histology • CDH1, RHOA mutations • CLDN18–ARHGAP fusion • Cell adhesion FIGURE 85-2  Molecular/genomic characterization of subtypes of gastric carcinomas. CIMP, CpG-island methylator phenotype; CIN, chromosomally unstable; EBV, EpsteinBarr virus-associated; GE, gastroesophageal; GS, genomically stable; MSI, microsatellite instability-associated. decreased mortality rates. This strategy has not been cost effective in populations in which the incidence of gastric cancer is much lower, such as in the United States. As noted above, in high-incidence areas, treatment of symptomatic H. pylori is a preventive measure. PRESENTING SYMPTOMS  Presenting symptoms include vague upper abdominal discomfort, hematemesis or melena, anorexia and early satiety, and unexplained weight loss. For patients with esophagogastric junction cancers, dysphagia or odynophagia may be the presenting symptom. Anemia may be found due to occult bleeding. These symp­ toms and signs lead to upper (and if site of bleeding is uncertain, lower) endoscopy and biopsy. Occasionally, imaging using CT performed to evaluate abdominal symptoms may identify gastric thickening or a gas­ tric mass leading to upper endoscopy. Physical examination can reveal left supraclavicular adenopathy (Virchow’s node), a periumbilical mass (Sister Mary Joseph nodule), a pelvic mass on rectal exam (Blumer’s shelf), ascites, or an ovarian mass (Krukenberg tumor). More com­ monly, physical examination is unrevealing. Upper endoscopy may reveal an ulcer or ulcerated mass, biopsy of which shows adenocarcinoma. For the diffuse subtype of gastric can­ cer, a mass or ulceration may not be seen, but rather, thickened gastric rugae may be noted. Initial biopsy may not reveal diffuse gastric cancer, which may track below the mucosal surface. In these patients, EUS may guide biopsy. Histopathology Classification of Primary Gastric Adeno­ carcinomas  The large majority (~85%) of gastric malignancies are adenocarcinomas or subtypes of adenocarcinoma. Other malignancies, discussed below, include neuroendocrine tumors (carcinoid tumors), primary gastric lymphomas, gastrointestinal stromal tumors (GISTs), and other rare malignancies. Using the Lauren classification, patholo­ gists classify adenocarcinomas on the basis of histopathology as intestinal (more common) or diffuse subtype (~20%). As noted above, the diffuse subtype is associated with inherited CDH1 mutations; in addition, in the TCGA genomic analysis of gastric cancer and in other genomic analysis studies, approximately a third of diffuse subtype cases had somatic CDH1 mutations. The intestinal subtype is associated with H. pylori infection and atopic gastritis. Histologic grade also influences the clinical course. Genomic analysis performed by several groups has resulted in molecular classifications of gastric cancer that may, in the future, Fundus EBV • PIK3CA mutation • PD-L1/2 overexpression • EBV-CIMP • CDKN2A silencing • Immune cell signaling Body MSI • Hypermutation • Gastric-CIMP • MLH1 silencing • Mitotic pathways inform staging systems; they already provide a better understanding of the driving factors in the development of gastric cancer and important information on treatment options as outlined above (Fig. 85-2). For example, the TCGA group reported the results of a multiplatform analysis of 295 patients with previously untreated gastric cancer; both Western and Asian patients were included in the analysis. Four sub­ types of gastric cancer were identified: high EBV burden, microsatel­ lite unstable with hypermutation, genomically stable (associated with the diffuse subtype), and chromosomal unstable. The Asian Cancer Research Group (ACRG), studying primary tumors from 300 Korean patients, analyzed gene expression profiles and found four subtypes: mesenchymal, microsatellite unstable, microsatellite stable with TP53 expressed, and microsatellite unstable with TP53 mutated. Clinical out­ come was correlated with genomic subtype in both studies, with micro­ satellite unstable tumors having the best outcome (in an era before use of immune modulation therapy) and genomically stable (TCGA) and mesenchymal (ACRG) types having the worst outcome. In addition to histopathology, as is the case for esophageal cancer, molecular diagnostics and genomic alteration analysis using NGS are an important part of the pathology workup. The molecular subtypes have therapeutic implications; for example, as discussed above, ~20% of gastric cancer or GEJ cancer patients’ tumors have overexpression or amplification of HER2/ERBB2, which would lead to the addition of agents such as trastuzumab-based therapy as part of systemic treatment for metastatic disease. Immune modulation therapy would be used in patients with hypermutated tumors, found by NGS (tumor mutation burden) or by polymerase chain reaction (PCR) for microsatellite instability (MSI). An evaluation for overexpression or amplification of HER2/ERBB2, quantification of PD-L1 by IHC, and assessment of MSI by PCR or deficient mismatch repair protein (dMMRP) expression should be a routine part of the pathology workup of patients with meta­ static gastric cancer. Claudin 18.2 has recently been identified as a tar­ get for therapy; if agents targeting Claudin 18.2 are approved by the U.S. Food and Drug Administration (FDA), an assay for this factor should be included in the pathologic evaluation of metastatic gastric cancer. More controversial is whether these assays should also be routinely performed in patients with potentially operable gastric cancer because, for example, the addition of trastuzumab to neoadjuvant chemotherapy has not yet been shown to change outcome. In large-volume centers, NGS is routinely performed on pretreatment biopsies. Currently, the finding on pathologic assays of positive tumor EBV (identified in 8–10% of gastric cancer patients) does not change therapeutic options. Staging  Once a diagnosis of a primary gastric adenocarcinoma is made, algorithms for clinical evaluation of stage include physical exam­ ination and imaging studies (Fig. 85-3; Table 85-2). Tumor-related biomarkers such as carcinoembryonic antigen (CEA) or CA19-9 may be elevated but are nonspecific (may be elevated in a number of other gastrointestinal and other site cancers). Diagnostic CT scan of the chest, abdomen, and pelvis should be performed. If metastatic disease is suspected on imaging, a biopsy of a metastatic site should be strongly considered to confirm stage IV disease, which changes the goals of care from potentially curative to palliative treatment and provides tis­ sue for molecular and genomic analyses. As is the case for esophageal cancer, FDG-PET/CT, which is more sensitive than diagnostic CT scan in identifying sites of metastatic disease, should be performed if the anatomic CT is negative for metastatic disease. Note, however, that FDG-PET may be noninformative (the primary tumor may not be FDG-avid, particularly in diffuse-type gastric cancer). If imaging does not reveal metastatic disease, EUS should be considered to determine depth of penetration of the primary tumor and the presence or absence of regional lymphadenopathy suspicious for metastasis. Lymph node biopsy and, on occasion, biopsy of left hepatic parenchymal lesions found on EUS can be performed at the same setting. Endoscopic biopsies usually provide enough tumor tissue for molecular diagnostic pathology testing for HER2/ERBB2, MSI/MMRP, and PD-L1 assess­ ment; it may not provide enough tissue for NGS genomic alteration analysis. If neoadjuvant therapy is planned, laparoscopy should be considered to allow evaluation of the peritoneal cavity, with peritoneal washing for cytology if no peritoneal metastases are visible. The perito­ neal cavity is a common site of metastases, especially from diffuse-type gastric cancer. The finding of peritoneal involvement either visibly or by positive cytology is staged as metastatic disease and generally rules out the chance for curative resection. The AJCC staging classification for gastric cancer is summarized in Table 85-2. Three staging classifications are provided: cTNM clinical staging (before any therapy has been given), pTNM pathologic staging (for patients not undergoing preoperative therapy), and a post–neoad­ juvant therapy classification staging (ypTNM). The three components take into account current standard-of-care options for therapy in which the AJCC prognostic stage groups from clinical staging guide therapeutic decisions. For example, after clinical evaluation, a large percentage of newly diagnosed patients will be found to have higherstage primary cancers (penetrating through the gastric wall [T3 or T4] or lymph node–positive tumors), in which case perioperative (neoad­ juvant) systemic therapy may be chosen. Pathologic examination of the resected specimen for prognostic stage classification must take into account exposure to preoperative therapies that may lead to down­ staging (thus, ypTNM staging). Nomograms have been developed for predicting outcome in patients undergoing surgery as initial treatment. CHAPTER 85 TREATMENT Gastric Cancer POTENTIALLY CURABLE GASTRIC CANCER: SURGERY Surgical removal of the primary tumor with negative microscopic margins (an R0 resection) and with resection of regional lymph nodes is currently the only curative therapy; with surgery alone, overall 5-year survival rates are approximately 25% (higher for very-early-stage tumors). If tumor cells are found at the margin of resection (R1) or if visible cancer is left at the time of surgical removal of the primary tumor (R2), surgery is palliative rather than curative. For patients with early-stage tumors (mostly clinical stage I), surgery without perioperative systemic therapy may be performed. For patients with more locally advanced tumors (clini­ cal stages IIA, IIB, III), who compose approximately 70% of newly diagnosed operable patients, multimodality therapy (surgery and systemic chemotherapy) improves overall survival. Both neoadju­ vant (preoperative) and postoperative systemic therapy are accepted approaches. If staging studies demonstrate a locally advanced can­ cer (or node positive), preoperative treatment is recommended in a medically fit patient. If surgery is performed first and a locally advanced cancer is found, postoperative chemotherapy or che­ motherapy plus chemoradiation is recommended. For selected very-early-stage gastric cancers (primary tumors that are ≤2 cm in diameter, are well to moderately differentiated, do not invade the deep submucosa [T1], and do not show lymphovascular invasion or lymph node metastasis), which are not commonly found in the United States, EMR or ESD may be performed by experienced gas­ troenterologists in place of surgical resection, with favorable results in studies in high-incidence areas such as Japan. Upper Gastrointestinal Tract Cancers For patients in whom the primary tumor is in the distal stom­ ach, a subtotal gastrectomy is the preferred surgical procedure. For tumors of the proximal stomach, the options for resection include total gastrectomy or, alternatively, proximal gastrectomy. Esophago­ gastrectomy is performed for tumors involving the GEJ. In selected patients, a jejunostomy feeding tube may be placed if postoperative radiation therapy is part of the treatment plan. As noted above, laparoscopy is commonly performed at highvolume centers before a final decision regarding the role of surgery. If staging has already demonstrated clinically suspicious lymph nodes or an advanced T stage tumor, but laparoscopy does not demonstrate peritoneal metastasis, perioperative chemotherapy is given before surgical resection. Palliative resection of the primary tumor is usually performed only if symptoms such as uncontrollable bleeding or obstruction are present that cannot be relieved by other means. No evidence of metastatic disease MI disease suspect FDG-PET/CT No MI disease MI disease PART 4 Oncology and Hematology EUS Stage 1 Consider laparoscopy Consider laparoscopy No peritoneal metastasis No MI peritoneum MI peritoneum Resection Neoadjuvant therapy pT1–2 N0 M0 pT3 Nany M0 Resection Active surveillance Adjuvant therapy FIGURE 85-3  Staging for gastric adenocarcinoma. CT, computed tomography; EUS, endoscopic ultrasound; FDG-PET, fluorodeoxyglucose positron emission tomography. As is the case for colorectal cancer, a correlation exists between the number of lymph nodes removed and sampled and outcome. Sentinel lymph node biopsy is not performed in gastric cancer outside of a research study setting. The goal is to examine at least 15 lymph nodes from the resected specimen; it is more contro­ versial whether more extensive lymph node resection itself affects outcome; the extent of lymphadenopathy can be classified using a D0–D3 system with a higher number meaning more extensive lymphadenopathy. In the United States, a modified D2 (D1+) resection preserving the spleen and avoiding pancreatectomy is recommended but should be performed by experienced surgeons at high-volume centers. Japanese investigators and others have used very extensive lymph node dissections, but studies have not demonstrated an advantage for a D3 resection. Both resection of the primary tumor and its regional lymph nodes can be performed laparoscopically in appropriate patients. Endoscopy and biopsy positive Diagnostic CT Biopsy if technically feasible Systemic therapy Stage 2/3 Systemic therapy In the hands of experienced surgeons, operative mortality would be anticipated to be ≤2%. NEOADJUVANT AND POSTOPERATIVE ADJUVANT THERAPY FOR RESECTABLE GASTRIC CANCER The large majority of potentially resectable Western gastric cancer patients have locally advanced tumors (cTNM stage IIA/B or III). Multimodality therapy using systemic chemotherapy plus surgery improves 5-year survival rates by 10–15% compared to surgery alone. An older but widely cited study, the MAGIC clinical trial, randomly assigned patients with potentially resectable disease to receive perioperative chemotherapy or to proceed directly to surgery. Five-year overall survival for patients undergoing surgery alone was 23%; for those receiving pre- and postoperative chemotherapy, it was 36%. On the basis of this and other clinical trials, for most medically fit patients with stage cTNM II and III resectable gastric cancers, preoperative systemic chemotherapy followed by resection and, if tol­ erable, postoperative chemotherapy is a standard approach. Because it is challenging to give postgastrectomy systemic therapy using currently employed regimens (<50% of patients receive or complete postoperative treatment), total neoadjuvant therapy is favored at some centers. For patients with MSI/hypermutated tumors, immune modulation therapy (PD-1/PD-L1 or PD-1 plus CTLA-4 agents) can be considered in place of chemotherapy, although substantial pathologic response rates were seen in a small number of patients in the DANTE trial using FLOT alone. Preoperative chemoradiation as given for esophageal cancers is usually used for GEJ tumors. If an R1 or R2 resection is performed, postoperative chemoradiation can be considered. Use of postoperative chemoradiation therapy, with exceptions outlined above, did not improve outcome when com­ pared to systemic chemotherapy alone. Preoperative chemotherapy followed by chemoradiation is under study. For patients being treated with multimodality therapy, close interactions among the surgeon, medical oncologist, and radiation oncologist are essential. Clinical trials have compared different preoperative cytotoxic chemotherapy regimens, most of which include a platinum com­ pound—either cisplatin or oxaliplatin. Currently, a platinum compound plus a fluorinated pyrimidine, such as fluorouracil or capecitabine, given for three to four cycles before surgery is a standard-of-care option. Drug combinations are favored; for very fit patients, a combination of FLOT may be chosen. An alternative is, for example, the FOLFOX regimen, which includes fluorouracil, leucovorin, and oxaliplatin. Addition of trastuzumab to preop­ erative chemotherapy has not improved outcomes for patients with HER2-positive cancers. Careful monitoring of chemotherapyrelated toxicities with appropriate dose modifications is important. For patients receiving preoperative systemic chemotherapy and undergoing an R0 D2/D1+ dissection, postoperative chemoradia­ tion therapy has not improved outcome. For patients in whom the primary tumor has been resected and who did not receive preoperative chemotherapy, who are found to have stage II or III cancers, or who have <15 lymph nodes found in the resected specimen (less than D2 resection), postoperative che­ motherapy or chemoradiation is a treatment option. Chemotherapy and chemoradiation therapy may also be given for unresectable cancers in selected patients. As noted above, plasma ctDNA as a measure of minimal residual disease (regional or metastatic cancer not identifiable by current imaging modalities) is being studied. Data from other gastrointestinal tumors suggest that conversion of a positive ctDNA assay to negative after systemic postoperative therapy is associated with a better outcome. PALLIATIVE THERAPY FOR INCURABLE GASTRIC CANCER Patients with clinical stage IV gastric cancers with an adequate per­ formance status should be offered systemic drug therapies. Small clinical trials performed in the 1980s and 1990s showed a survival benefit for systemic therapy compared to best supportive care only. As discussed above, genomic and molecular diagnostic analysis has identified several distinct cohorts of gastric cancer patients. These analyses guide therapy. While the cytotoxic chemotherapy regimens most commonly employed are still based on a platinum compound and a fluorinated pyrimidine (e.g., FOLFOX, as is used in the peri­ operative setting), a major advance has been the demonstration that immune modulation therapy plus chemotherapy improves outcome (including overall survival) compared to chemotherapy alone. In the CheckMate 649 trial, 1581 patients with HER2/ERBB2-negative advanced gastric or GEJ cancers were randomly assigned to receive nivolumab plus chemotherapy (oxaliplatin plus capecitabine or FOLFOX) versus chemotherapy alone. Overall survival, progres­ sion-free survival, and response rates were significantly better for patients receiving nivolumab plus chemotherapy; this effect was most marked for patients with PD-L1 CPS of >5. CheckMate 649 and other data have led to guidelines recommending use of immune modulation therapy plus chemotherapy as an option for first-line treatment for patients with HER2/EBB2-nonexpressing, PD-L1 CPS >5 metastatic gastric and gastroesophageal cancers; chemotherapy plus immune modulation therapy may also have benefit for patients with lower PD-L1 CPS scores. Those whose tumors have overex­ pressed or amplified HER2 should receive HER2-targeted agents such as trastuzumab or trastuzumab, pembrolizumab, plus cyto­ toxic chemotherapy. Beyond first-line therapy, additional HER2targeted therapy using agents such as trastuzumab-deruxtecan, a monoclonal antibody-drug conjugate, is recommended for patients whose tumors have amplification of HER2/ERBB2. For patients with metastatic MSI/dMMRP gastric cancers, immune modulation therapy using either PD-1 inhibitors such as pembrolizumab or combinations such as nivolumab plus ipilimumab may be employed as first-line therapy; guidelines include the option of immune therapy plus chemotherapy. When disease progresses after first-line treatment, other therapies include the combination of a VEGF receptor–targeted agent, ramu­ cirumab, either alone or in combination with paclitaxel. Immune modulation inhibitors are an option for second-line therapy for patients whose tumors are microsatellite unstable (e.g., nivolumab plus ipilimumab if single-agent pembrolizumab was used as firstline therapy). For patients with microsatellite stable gastric cancers (the large majority), immune modulators are an option if not used in the first-line setting, if PD-L1 is positive. As above, for patients with HER2/ERBB2-amplified tumors, trastuzumab-deruxtecan can be used. Several other cytotoxic agents have activity in the thirdline setting including trifluridine-tipiracil and irinotecan. Even with improvements in therapy including immune modulation therapy, the best results from clinical trials indicate overall survival for treated patients with stage IV disease is still only 12–15 months. Investiga­ tional studies include targeting Claudin 18.2, a cell surface type junc­ tion molecule that is overexpressed in ~50% of gastric cancers. In the SPOTLIGHT trial, previously untreated, HER2/ERBB2-negative patients assigned to zolbetuximab (targeting Claudin 18.2) plus FOLFOX chemotherapy had an improvement in survival compared to those receiving FOLFOX chemotherapy alone. Zolbetuximab plus chemotherapy may become another first-line option for advanced gastric cancer. Additional studies targeting Claudin 18.2 including those using chimeric antigen receptor (CAR) T cells are underway. CHAPTER 85 Upper Gastrointestinal Tract Cancers Radiation therapy using shorter regimens may be employed to palliate bleeding. For patients with advanced incurable disease, other supportive measures include placement of a duodenal stent to relieve gastric outlet obstruction; in selected patients, surgical pro­ cedures for gastric outlet obstruction may be performed. Radiation therapy might be used if not previously given. Enteral feeding using a jejunostomy tube may support nutritional needs. GASTRIC LYMPHOMAS Lymphomas of the stomach are an uncommon (~3%) but important subgroup of gastric malignancies. They are extranodal non-Hodgkin’s lymphomas (NHL). The gastrointestinal tract is the most common site for extranodal NHL, and the stomach is the most common site within the gastrointestinal tract. The presenting symptoms can be similar to those of the much more common adenocarcinoma of the stomach described above, including pain, anorexia, and bleeding. Symptoms of fever and night sweats occur in 10–15% of patients with gastric NHL. Because the treatment options are so different, obtaining adequate tis­ sue for definitive pathologic examination is crucial in diagnosing both gastric lymphomas (as opposed to adenocarcinoma) as well as defin­ ing the subtype of lymphoma. On occasion, this may be challenging because, similar to diffuse subtype adenocarcinoma, lymphomas may track below the mucosal surface. A fine-needle aspirate may not be suf­ ficient; multiple deep biopsies or mucosal resection may be needed to provide enough tissue for definitive pathologic assessment. Potential driving forces in the development of gastric lymphomas include active or prior H. pylori infection, which is associated with mucosa-associated lymphoid tissue (MALT) subtype gastric lympho­ mas and has been described as a potential driver in some patients with diffuse large B-cell lymphomas (DLBCLs). MALT lymphomas may develop in nearly any organ, but the stomach is the most frequent pri­ mary site, accounting for ~35% of all MALT lymphomas. Identifying a MALT lymphoma is important because antibacterial therapy directed against H. pylori alone can be a highly effective treatment. Other infec­ tions should be considered either as driving factors or as risks from treatment, such as reactivation of hepatitis B virus (HBV); testing for HBV is recommended before initiation of lymphoma therapy. Hepatitis C infection has been associated with DLBCL and with marginal zone lymphomas. Other forms of NHL may involve the stomach either as primary gastric lymphoma or as a secondary site of disease, including both B-cell (e.g., mantle cell lymphoma, Burkitt’s lymphoma, and fol­ licular lymphoma) and T-cell lymphomas (e.g., enteropathy-associated T-cell lymphoma, anaplastic large-cell lymphoma, and peripheral T-cell lymphoma). Staging is performed using similar imaging modalities as for gastric adenocarcinoma, but the staging systems are different (see below, and presented in more detail in the chapter on lymphomas [see Chap. 113]). As a staging study, FDG-PET/CT is performed, as well as a contrastenhanced, diagnostic-quality CT. FDG-PET/CT is used both as an initial staging study and to assess response. EUS may be used to deter­ mine depth of invasion in patients in whom no evidence of metastatic disease is noted. Examination of the peripheral blood and bone mar­ row aspirate should be considered as part of the workup. In all patients with gastric lymphoma, H. pylori infection status should be evaluated. If H. pylori testing is negative by histopathology, noninvasive testing by either stool antigen test or urea breath test should be used. PART 4 Oncology and Hematology ■ ■STAGING The TNM staging system is not employed for gastric lymphomas. Several classification systems are used for lymphomas, including the Lugano staging system (a modification of Ann Arbor staging), the revised World Health Organization (WHO) Fifth Edition of the WHO Classification of Haematolymphoid Tumours (WHOHAEM5), and the International Consensus Classification (ICC). These are discussed in Chap. 113 on lymphomas. The Lugano staging system for gastroin­ testinal lymphomas is still widely used; it divides patient groups into stages I, II, III, and IV. Stage I tumors are limited to the gastric wall; stage II tumors have regional lymph node involvement or invasion of local structures; stage III tumors have lymph node involvement above and below the diaphragm. Stage IV tumors have either more extensive lymph node involvement or have distant metastasis, including to the bone marrow or other extranodal sites. ■ ■PATHOLOGIC CLASSIFICATION The two most common histologic subtypes of gastric lymphoma are marginal zone B-cell lymphomas (gastric marginal zone B-cell lympho­ mas or MALT; ~40% of newly diagnosed patients) and DLBCLs (~55%). The distinction is critical because therapeutic options are different. The large majority of MALT cases are associated with H. pylori infection. The finding of a t(11;18) translocation identifies a subgroup less likely to respond to H. pylori eradication (or in non-H. pylori–associated MALT). This translocation may be detected using PCR or fluorescent in situ hybridization (FISH); it creates a chimeric protein composed of the amino terminal of API1 (apoptosis inhibitor) and the carboxy terminus of MALT1, leading to activation of nuclear factor-κB signaling. Note that even H. pylori–negative MALT tumors may respond to anti–H. pylori therapy. Other, rarer subtypes of primary gastric lymphomas include those of T-cell lineage. TREATMENT Gastric Lymphoma Unlike adenocarcinoma of the stomach, surgical resection has no role in the treatment of primary gastric lymphoma in the absence of complications of therapy such as perforation or uncontrollable bleeding. Resection of gastric lymphoma does not improve clinical outcomes. For patients with MALT lymphoma, eradication of H. pylori with antibiotics is highly effective therapy. If tests for H. pylori are positive and t(11;18) translocation assay is negative, one of the cur­ rently accepted antibiotic regimens for treating H. pylori should be the initial therapy. H. pylori eradication is associated with high response rates including complete remissions in the majority of patients. Treatment with an anti–H. pylori regimen may induce remission even in patients in whom standard testing for H. pylori, described above, is negative. The time to remission may be pro­ longed (in some studies averaging 15–16 months); therefore, careful monitoring is important before determining that a MALT tumor is not responding to anti–H. pylori therapy. For patients in whom the t(11;18) translocation assay is positive, options for therapy include anti–H. pylori antibiotic therapy plus involved-field radiation ther­ apy or, if radiation is contraindicated, the use of single-agent ritux­ imab, a monoclonal antibody targeting CD20. For patients who are H. pylori negative, in whom anti–H. pylori therapy may have been used without response, moderate-dose (24–30 Gy) involved-site radiation therapy or single-agent rituximab is a treatment option. For selected, more advanced, stage IV MALT patients who have not responded to or who have progressed after receiving anti–H. pylori antibiotic therapy and/or rituximab, cytotoxic che­ motherapy regimens such as R-CHOP (rituximab, cyclophospha­ mide, doxorubicin, vincristine, and prednisolone), dose-adjusted R-EPOCH (an infusional regimen of rituximab, etoposide, prednis­ olone, vincristine, cyclophosphamide, and doxorubicin), or ritux­ imab and lenalidomide may be considered. DLBCL may be a result of transformation from more indolent MALT lymphoma or may arise de novo. De novo tumors are more likely to be BCL2 and CD10 positive. MALT lymphomas that have transformed to DLBCLs are more frequently BCL2 and CD10 negative. For patients with DLBCL, earlier-stage tumors may be treated by combination chemotherapy alone or chemotherapy plus involvedfield radiation therapy. For more advanced gastric DLBCL tumors, chemotherapy using the R-CHOP or R-EPOCH regimen is stan­ dard therapy. Some reports have suggested that eradication of H. pylori is effective treatment for early-stage DLBCL when the patient also has H. pylori. UNCOMMON TUMORS OF THE ESOPHAGUS AND STOMACH ■ ■GASTROINTESTINAL STROMAL TUMORS GISTs are rare tumors of the gastrointestinal tract associated with activating somatic mutations in the cKIT (the majority) or PDGFRA genes; in a minority of cases, neither gene is mutated. GISTs arise from Cajal cells, which bridge between the autonomic nerves to the muscle layer of the bowel. The stomach is the most frequent primary site (~60%), followed by the small bowel in about 25%. As endoscopy for other indications has become more widely used, otherwise asymp­ tomatic and probably clinically insignificant small GISTs have been identified more frequently; it is not clear that the actual incidence has substantially increased. Symptoms associated with GISTs include acute gastrointestinal bleeding leading to melena and/or hemateme­ sis. Anemia may be reflected in generalized weakness. With larger tumors, abdominal distention and pain may be presenting symptoms. At endoscopy, a nonspecific smooth bulging mass covered by normal mucosa is the most frequent finding. Initial biopsy may not reveal a mesenchymal neoplasm. The radiologic features found on diagnostic CT scan (which may identify an asymptomatic tumor) may raise the question of a GIST tumor. EUS can be performed, but if biopsy is done, it may not provide an adequately cellular specimen to allow genomic sequencing, which is required to help guide systemic therapy (if needed). Histologically, a spindle cell neoplasm is the most common subtype (~70%), with epithelioid cells making up 20%; 10% of cases are mixed histology. KIT expression is found in ~95% and PDGFRA in ~80% of cases. NGS is usually used to assess for gain-of-function KIT, PDGFRA, or other, rarer mutations. For nonmetastatic GIST tumors, risk of recurrence assessment (guiding use of postoperative therapy) is based on the size of the pri­ mary tumor, mitotic index, and location in the gastrointestinal tract. For gastric GISTs, resected tumors ≤2 cm with a mitotic index of ≤5% have a near 0 risk of progression. For larger tumors, especially those ≥10 cm, with a mitotic index >5%, the risk is moderate to high. Post­ operative adjuvant imatinib for 3 years is a standard-of-care option. Avapritinib is used for tumors with certain PDGFRA mutations. For patients with metastatic disease, imatinib (for KIT mutation–bearing tumors) or avapritinib (targeting PDGFRA) is used; the location of the KIT mutation (exon 11 vs 9) is associated with degree of effectiveness. However, resistance almost invariably develops, and the development of newer agents effective in tumors with secondary mutations is a high priority; ripretinib, which targets both KIT and PDGFRA, is now also FDA approved. ■ ■SMALL-BOWEL NEOPLASMS Small-bowel neoplasms make up ~3% of gastrointestinal tumors; in 2023, 12,000 new cases are expected in the United States. The spectrum of malignant small-bowel neoplasms includes neuroendocrine tumors (NETs; carcinoid), adenocarcinomas, lymphomas, and GISTs. In the United States, NETs, which have increased in incidence, are slightly more frequent (40–45%) than adenocarcinomas (30–40%), with the remainder mostly lymphomas and ~8% GISTs. The duodenum is the most common portion of the small bowel in which malignancies develop (~50%), with ~30% occurring in the jejunum and 20% in the ileum. NETs are the most common benign and malignant tumors of the ileum. Risk factors for the development of small-bowel adeno­ carcinoma include inflammatory bowel disease (Crohn’s disease); inherited germline mutation syndromes such as Lynch syndrome, familial adenomatous polyposis (FAP), and Peutz-Jeghers syndrome; and celiac disease (which is also associated with an increased risk for lymphomas). While an asymptomatic small-bowel primary adenocarcinoma might be found during surveillance in patients at high risk (e.g., FAP), for many small-bowel tumors, the finding of positive stool occult blood, unexplained anemia, or small-bowel obstruction leads to the diagnosis. Both adenocarcinoma and lymphomas might present with perforation. Evaluation by diagnostic CT imaging may reveal a smallbowel lesion. CT and/or magnetic resonance enterography (CTE or MRE) have a high positive predictive value (for adenocarcinoma, MRE appears to be more accurate). A variety of endoscopic techniques are used for diagnostic evaluation of the small bowel, including deviceassisted enteroscopy (DAE), e.g., double-balloon enteroscopy; smallbowel capsule endoscopy (SBCE) may also be employed. DAE allows tissue diagnosis; a tattoo helps localize the small bowel neoplasm (SBN) for resection; DAE may also allow stent placement for palliation of obstruction. SBCE is contraindicated in the setting of obstruction. As is the case for gastric imaging studies, deep learning artificial intelli­ gence is being studied to improve the analysis of small-bowel imaging. For NETs, a gallium-68 or copper-64 DOTATATE scan may identify both the primary site as well as metastatic disease. Blood tumor bio­ markers are nonspecific for the primary site (e.g., CEA or CA19-9 for adenocarcinoma); these assays are better used to monitor response or progression of disease rather than for diagnosis. The median age at diagnosis for sporadic small-bowel adeno­ carcinoma is in the seventh or eighth decade of life, but genetically predisposed patients and those with inflammatory bowel disease may be diagnosed at a much earlier age. African Americans have a higher incidence of small-bowel cancer than whites. While systemic therapies are usually modeled on agents used to treat colorectal cancer, genomic analyses have indicated that small-bowel adenocarcinoma has distinct genomic alterations compared to either colorectal or gastric cancers. Genomic alterations less frequent in small-bowel than in colorectal cancers include TP53, BRAF V600E, and APC mutations, whereas the rate of KRAS mutations is similar to colorectal cancer (a genomic analysis of Chinese small-bowel cancer patients, mostly duodenal cancers, noted a somewhat different profile than U.S. patients). Within small-bowel sites, the most striking difference is the higher rate of ERBB2 alterations (of which a minority are amplifications) in duodenal cancers. Not surprisingly, because Lynch syndrome increases the risk of small-bowel adenocarcinoma, 15–20% of these tumors are MSI high or mismatch repair deficient; small-bowel adenocarcinoma associated with celiac disease also may have an increased rate of MSI-high tumors. MSI/MMRP status should be assessed in all patients with small-bowel adenocarcinoma. Somatic tumor genomic analysis may suggest a germline mutation, but appropriate genetic testing for a germline driver mutation should be performed in all patients with small-bowel adenocarcinoma. Small-bowel adenocarcinoma has its own staging classification in the eighth edition of the AJCC Cancer Staging Manual. TREATMENT Small-Bowel Adenocarcinomas Surgical resection with negative microscopic margins (R0), as is the case for other gastrointestinal tumors, is the best chance for cure. For duodenal adenocarcinomas, a Whipple procedure may be needed; for more distal duodenal cancers and jejunal adenocar­ cinomas, a segmental resection with adequate margins should be performed. Distal ileal tumors may require right hemicolectomy. CHAPTER 85 Small-bowel cancers are frequently found with locally advanced disease at the time of diagnosis. If the tumor is resectable, post­ operative adjuvant systemic therapy is currently recommended for lymph node–positive patients, using regimens such as those employed for colorectal cancer (capecitabine and oxaliplatin or FOLFOX). Benefit from adjuvant therapy has not yet been proven. Small-bowel cancers developing in patients with Lynch syndrome probably have a better prognosis; if colorectal cancer is a model, postoperative adjuvant therapy for patients with Lynch syndrome may include consideration of immune modulation therapy. For duodenal cancers, chemoradiation is considered if the resection margins are still positive. Upper Gastrointestinal Tract Cancers For patients with advanced metastatic disease, in the absence of Lynch syndrome or a hypermutated tumor, similar cytotoxic regi­ mens as deployed for gastric (duodenal) or colon cancers (jejunum or ileum) have been widely used. For tumors that are MSI high or dMMRP positive, immunotherapy is indicated; for tumors that are HER2 amplified or BRAF mutated, targeted therapy may be useful. ■ ■SMALL-BOWEL GASTROINTESTINAL STROMAL TUMORS Like small-bowel adenocarcinomas, small-bowel GISTs may pres­ ent with obstruction or bleeding. Diagnostic techniques are those employed for other small-bowel neoplasms. While the pathological criteria for malignant potential are somewhat different than those used for gastric GISTs, postoperative management and treatment of meta­ static disease are the same as those described above for gastric GIST. ■ ■BENIGN NEOPLASMS OF THE SMALL BOWEL As is the case for malignant small-bowel tumors, benign neoplasms of the small bowel are rare. In addition to cancers, the precursor lesion adenomas or hamartomas (from which cancers develop) may be driven by inherited cancer susceptibility genes (e.g., FAP, Lynch syndrome, Peutz-Jeghers syndrome). Other benign neoplasms include lipomas, leiomyomas, neurofibromas, and benign lymphoid nodular hyperplasia. Patients with benign small-bowel neoplasms not associated with an inherited cancer susceptibility gene (in which case, a benign tumor may be found during surveillance) are usually asymptomatic. A mass may be noted on an imaging study (usually a CT) ordered for another reason. Workup for occult or overt bleeding or intussusception of the bowel may lead to the discovery of a benign small-bowel neoplasm. Diagnostic evaluation is similar to that described above for malig­ nant tumors. In general, benign neoplasms, if found during surveil­ lance, are removed endoscopically, if technically feasible, to decrease the risk of intussusception in Peutz-Jeghers syndrome. Mucosectomy may be used to treat bleeding hemangiomas. NEUROENDOCRINE TUMORS OF THE ESOPHAGUS, STOMACH, AND SMALL BOWEL Neuroendocrine neoplasms include NETs (more well differentiated, classified as grades 1–3) and neuroendocrine carcinomas (NECs). Neuroendocrine neoplasms including pancreas NETs are described in detail in Chap. 89. The following describes NET and NEC of the esophagus, stomach, and small bowel. ■ ■ESOPHAGEAL AND GASTRIC NEUROENDOCRINE TUMORS NETs of the esophagus are rare, accounting for <1% of gastrointestinal NETs. Presenting symptoms are similar to those of SCC or adenocarci­ noma of the esophagus, with dysphagia or odynophagia or with more nonspecific symptoms such as substernal discomfort or burning consis­ tent with reflux esophagitis. A potential driving factor of NEC is smok­ ing. The initial diagnostic evaluation includes upper endoscopy and biopsy. Pathology may reveal a well-differentiated NET (grades 1–3; grade guided by percent Ki-67 positivity) with a low to relatively low metastatic potential; at the other end of the spectrum are small-cell or large-cell NECs, which are fully malignant and frequently metastasize. In the absence of metastatic disease, EUS to assess depth of penetra­ tion and presence or absence of regional lymph node metastasis is fre­ quently performed. Imaging studies include CT; for high-grade NEC, an FDG-PET/CT scan to assess for metastatic disease is done. For NET, somatostatin receptor imaging studies such as gallium-68 or copper-64 DOTATATE scans may be performed if metastatic disease is suspected. PART 4 Oncology and Hematology Gastric NETs (also called gastric carcinoid tumors) represent 7–9% of gastrointestinal NETs but <1% of gastric neoplasms; several types have been described, based in part on whether there is associ­ ated achlorhydria and hypergastrinemia. For all gastric NETs, initial evaluation includes upper endoscopy and biopsy. EUS may be help­ ful in assessing depth of invasion for larger tumors and for assessing regional lymph node metastases in higher grade tumors. Somatostatin analogue imaging using DOTATATE scanning may be performed if metastatic disease is suspected. As is the case for other NETs, the finding of unresectable metastatic disease that is DOTATATE avid not only provides staging information but also guides potential therapy using somatostatin receptor–targeted therapy. See Chap. 89 for a more detailed discussion. TREATMENT Esophageal Neuroendocrine Tumors For early-stage, lower-grade NETs, endoscopic resection including EMR or ESD may be performed. Surgery may be employed for more advanced-stage locoregional but not metastatic NET. Smallcell or large-cell NECs that are not metastatic are usually treated with chemotherapy plus external-beam radiation therapy using chemotherapy regimens similar to those employed for small- and large-cell neuroendocrine cancers of the lung (Chap. 83). For metastatic NETs, somatostatin receptor DOTATATE scans guide therapy. See below discussion for small-bowel NETs for discus­ sion of use of somatostatin receptor blockade with agents such as octreotide or lanreotide and the use of peptide-related radiation therapy (PRRT). Systemic therapy for metastatic small- and largecell esophagogastric NECs is also modeled on therapy for small- and large-cell thoracic NECs. TREATMENT Gastric Neuroendocrine Tumors Type 1 tumors can be treated endoscopically with polypectomy or endomucosal resection. For larger tumors (>2 cm) or tumors invad­ ing through the muscularis or to regional lymph nodes, surgical resection is recommended. Type 2 tumors have a higher risk for regional lymph node metastasis and are usually treated surgically, although selected patients may have a combination of endoscopic resection and limited surgical resection. Type 3 tumors are not asso­ ciated with elevated gastrin levels and have a higher propensity for regional lymph node metastasis and distant metastasis. Surgery is the treatment of choice for localized type 3 tumors, although EMR has been used in selected patients. Adenocarcinoma of the stomach may be found in 5–10% of type 3 tumors. The role of surgery in mixed NEC-adenocarcinoma neoplasms is not well established. ■ ■NEUROENDOCRINE TUMORS (CARCINOID) OF THE SMALL BOWEL In the United States, NET are the most common small-bowel neo­ plasms. For not yet identified reasons, the incidence of small-bowel carcinoid tumors has markedly increased over the past several decades. A recent study found a 9% incidence of inherited germline cancer susceptibility genes in patients with small-bowel NET; however, it is unlikely that this is the cause of the increased incidence (Chap. 89). Even with an increase in incidence, small-bowel NETs are still uncom­ mon (~12 cases per million in the United States); the disease is more common in African Americans than whites. Anatomically, the ileum is the most common part of the small bowel affected (~49%), followed by the duodenum and the jejunum. The same grading system, based on histology and the Ki-67 prolifera­ tive index or mitotic count, as for other gastrointestinal NETs is used. In the absence of metastatic disease to the liver in the subgroup of patients whose tumors are functional (i.e., produce a hormone, usually serotonin; a duodenal NET may produce gastrin), presenting symp­ toms may be vague abdominal discomfort until or unless small-bowel obstruction occurs. Carcinoid syndrome (including diarrhea and/ or flushing) may occur in patients whose tumors are diagnosed with already established hepatic metastasis. Because the liver is very efficient at clearing serotonin on first pass, carcinoid syndrome as a result of small-bowel carcinoid tumors usually does not occur in the absence of hepatic metastasis. Clinical evaluation includes a diagnostic-quality CT or MRI of the abdomen and pelvis. For duodenal NET, upper endoscopy with EUS is also performed. For ileal NET, colonoscopy with evaluation of the terminal ileum is performed. Imaging studies are similar to those used for diagnosis and localization of small-bowel adenocarcinomas. Somatostatin analogue imaging using gallium-68 or copper-64 DOT­ ATATE PET/CT is helpful in assessing extent of disease in patients whose tumors are somatostatin analogue avid, as well as in identify­ ing patients who may benefit from therapy targeting the somatosta­ tin receptor. Plasma or urine assay for 5-hydroxyindoleacetic acid (5-HIAA) is performed to assess for a functional small-bowel NET. The AJCC Ninth Edition Cancer Staging Manual has a specific small-bowel NET TNM stage classification (for the duodenum and ampulla and for the jejunum and ilium). The majority of patients present with locoregional disease, with approximately 40% having identified lymph node metastasis. Ten to 15% of patients have metastatic disease (usually to the liver) at the time of initial diagnosis. Initial management should be surgical resection with curative intent; for patients with extensive adenopathy involving the root of the mesen­ tery, vascular reconstruction may be required. Since small-bowel NETs may involve multiple tumors (15–30% of patients), the entire small bowel should be carefully examined at surgery. For patients with func­ tional carcinoid tumors, somatostatin analogue therapy using agents such as octreotide should be given before the induction of anesthesia to avoid a carcinoid crisis. For patients with hepatic metastasis, resec­ tion or regional therapy including ablation or hepatic artery emboliza­ tion for functional tumors may provide effective palliation. Carcinoid syndrome may also be palliated by somatostatin receptor–targeted therapy in the patients in whom DOTATATE scanning is positive (the majority of patients with carcinoid syndrome), including agents such as octreotide or lanreotide, or by peptide-directed radiation therapy using agents such as lutetium-177. Everolimus, an mTOR kinase inhibitor, has modest activity in metastatic small-bowel carcinoid tumors. # 15 - 86 Colorectal Cancer ### 86 Colorectal Cancer ■ ■FURTHER READING Ben-Aharon I et al: Early-onset cancer in the gastrointestinal tract is on the rise-evidence and implications. Cancer Discov 13:538, 2023. Cancer Genome Atlas Research Network: Comprehensive molec­ ular characterization of gastric adenocarcinoma. Nature 513:202, 2014. Cancer Genome Atlas Research Network et al: Integrated genomic characterization of oesophageal carcinoma. Nature 541:169, 2017. Choi IJ et al: Helicobacter pylori and prevention of gastric cancer. N Engl J Med 378:2244, 2018. Choi IJ et al: Family history of gastric cancer and Helicobacter pylori treatment. N Engl J Med 382:427, 2020. Dermawan JK et al: Novel genomic risk stratification model for pri­ mary gastrointestinal stromal tumors (GIST) in the adjuvant therapy era. Clin Cancer Res. 29:3974, 2023. Hoeppner J et al: Perioperative chemotherapy or preoperative chemo­ radiotherapy in esophageal cancer. N Engl J Med 392:323, 2025. Janjigian YY et al: Pembrolizumab plus trastuzumab and chemo­ therapy for HER2-positive gastric or gastro-oesophageal junction adenocarcinoma: Interim analyses from the phase 3 KEYNOTE-811 randomised placebo-controlled trial. Lancet 402:2197, 2023. Pourmand K, Itzkowitz SH: Small bowel neoplasms and polyps. Curr Gastroenterol Rep 18:23, 2016. Watanabe M et al: Recent progress in multidisciplinary treatment for patients with esophageal cancer. Surg Today 50:12, 2020. David P. Ryan Colorectal Cancer ■ ■INCIDENCE Colorectal cancer is the most common cancer of the gastrointestinal system in the United States. In 2024, 153,000 cases are expected, with ~106,000 cases in the colon and 46,000 cases in the rectum. It is the second most common cause of death from cancer (lung cancer is first) with 53,000 expected deaths. There is a slight male predominance in the incidence of colorectal cancer, and it is more common in black Americans than white Americans. Since 1985, there has been a steady decline in the incidence of colorectal cancer in both men and women likely due to the adoption of widespread screening guidelines for colonoscopy. This decline is seen in adults older than 50. However, a steady increase in the incidence of colorectal cancer has been seen in patients under the age of 50. While in older adults a gradual shift into predominantly right-sided cancer has been noted, a gradual increase in left-sided colon and rectal cancers has been seen in patients under the age of 50. This increase in incidence has resulted in an increase in mortality rates from colorectal cancer among young adults. Colon cancer is now the leading cause of cancer death for young men age 20–49 and the second leading cause of cancer death after breast cancer for women age 40–49. ■ ■ADENOMATOUS POLYPS Most colorectal cancers arise from adenomatous polyps as opposed to a hyperplastic polyp, hamartomatous polyp, or a serrated polyp. While adenomatous polyps are clearly premalignant, only a minority of adenomatous polyps will ever develop into an adenocarcinoma. Adenomatous polyps are common in the United States and western societies, with approximately 25% of people having adenomatous polyps by age 50. The rate steadily rises as people age, and as many as 50% of 70-year-old people will have adenomatous polyps. Less than 5% of adenomatous polyps are expected to progress to an adenocarcinoma. The vast majority of adenomatous polyps are asymptomatic and do not bleed. The risk of progression to cancer is associated with size of the polyp and the histology. Villous adenomas develop into cancer three­ fold more often than tubular adenomas. ■ ■MOLECULAR PATHOGENESIS The majority of colon cancers arise from a series of genetic and epi­ genetic events involving tumor suppressor genes and oncogenes. Three major types of molecular pathways are involved in sporadic colorectal cancer: the chromosomal instability (CIN) pathway, the mismatch repair (MMR) pathway, and the CpG island methylation pathway (CIMP). The CIN pathway is the most common molecular pathway associated with colon cancer and is characterized by early loss of the adenomatous polyposis coli (APC) gene, which is a tumor suppressor gene. Subsequent mutations in important oncogenes involving the MAP kinase pathway, such as KRAS and BRAF, are acquired sequen­ tially. Finally, loss of p53 tumor suppressor gene is a common final step. The defects in the MMR pathway in sporadic colon cancer are often caused by hypermethylation of the promoters for mismatch repair genes. This results in a phenotype known as microsatellite instability high (MSI-high), which is characterized by altered sizes of various mono- and di-nucleotide repeat sequences. A defect in the MMR pathway is the etiology of Lynch syndrome, which involves a germline mutation in one of the genes encoding for the proteins involved in the MMR pathway. It is critical to test for MSI-high because these tumors are dramatically sensitive to immune checkpoint inhibition and less sensitive to chemotherapy. The third major molecular pathway is the CIMP phenotype. These tumors are often right sided and associated with methylation of MLH1. They can be either MSI-high or microsat­ ellite stable (MSS). The three major pathways are not mutually exclu­ sive, and often overlapping changes can be seen in individual cancers. CHAPTER 86 Colorectal Cancer ■ ■ETIOLOGY AND RISK FACTORS Risk factors for the development of colorectal cancer are listed in Table 86-1. ■ ■HEREDITARY FACTORS AND SYNDROMES Advances in germline genotyping have made this technology more widely available to the population of patients getting colon cancer. Approximately 10% of all patients with colorectal cancer will have an inherited, germline predisposition to colorectal cancer, and this rises to ~15% of young adults with colorectal cancer (Table 86-2). The germline mutations can be divided into high penetrance and moderate penetrance based on their risk of colon cancer development. Familial Adenomatous Polyposis (FAP)  FAP and its variants are due to a mutation in the APC gene located on chromosome 5q2122. It is inherited in an autosomal dominant pattern, although a sig­ nificant minority of cases are due to de novo mutations. FAP accounts for <1% of all colon cancer and is characterized by the development of hundreds to thousands of colonic polyps. It is diagnosed in childhood in the classical form of FAP, and colorectal cancer develops in virtually 100% of individuals if left untreated. An attenuated form of FAP is char­ acterized by tens of polyps and cancers developing at a later age. FAP TABLE 86-1  Risk Factors for the Development of Colorectal Cancer Diet: Animal fat, obesity Hereditary syndromes   Polyposis coli   MYH-associated polyposis   Nonpolyposis syndrome (Lynch’s syndrome) Inflammatory bowel disease Streptococcus bovis bacteremia Tobacco use TABLE 86-2  Heritable (Autosomal Dominant) Gastrointestinal Neoplasia Syndromes DISTRIBUTION OF POLYPS HISTOLOGIC TYPE SYNDROME Familial adenomatous polyposis Large intestine Adenoma Common — Gardner’s syndrome Large and small intestines Adenoma Common Osteomas, fibromas, lipomas, epidermoid cysts, ampullary cancers, congenital hypertrophy of retinal pigment epithelium Turcot’s syndrome Large intestine Adenoma Common Brain tumors MYH-associated polyposis Large intestine Adenoma Common None Lynch syndrome (nonpolyposis syndrome) Large intestine (often proximal) Adenoma Common Endometrial and ovarian tumors (most frequently), gastric, genitourinary, pancreatic, biliary cancers (less frequently) Peutz-Jeghers syndrome Small and large intestines, stomach Hamartoma Rare Mucocutaneous pigmentation; tumors of the ovary, breast, pancreas, endometrium Juvenile polyposis Large and small intestines, stomach Hamartoma, rarely progressing to adenoma can be associated with extracolonic manifestations such as desmoid tumors (Gardner’s syndrome) or brain tumors (Turcot’s syndrome). Patients with classic FAP should undergo colectomy, as well as those patients with attenuated FAP that is too difficult to screen endoscopi­ cally. Colectomy patients with FAP should be followed for extracolonic tumors and manifestations. Chemoprevention with nonsteroidal antiinflammatory drugs (NSAIDs) can be tried because it has been asso­ ciated with polyp regression and delayed progression, but its overall effect on cancer prevention has not been established. PART 4 Oncology and Hematology MUTYH-Associated Polyposis (MAP)  MAP is an autosomal recessive polyposis syndrome caused by a biallelic mutation in the MUTYH gene. The MUTYH gene is a base excision repair gene, and failure of base excision repair leads to somatic CG-AT transversions in multiple genes. MAP accounts for <1% of colorectal cancers. The clini­ cal presentation of MAP overlaps with attenuated FAP in that individu­ als may have tens of polyps that develop by the fifth or sixth decade of life. Individuals with MAP are at increased risk of duodenal cancers and thyroid cancer. Screening and colectomy guidelines for this syndrome are less clear than for polyposis coli, but annual to biennial colonoscopic surveillance is generally recommended starting at age 25–30 years. Lynch Syndrome  Lynch syndrome, previously known as heredi­ tary nonpolyposis colon cancer, is the most common inherited pre­ disposition to colorectal cancer, accounting for ~3% of all colorectal cancers, and confers an up to 17-fold risk of colorectal cancer. Lynch syndrome is due to a mutation in one of the MMR genes. The MMR genes are MLH1 (Chr 3p22), MSH2 (2p21-16), MSH6 (2p16), and PMS2 (7p22). Lynch syndrome can also occur due to deletion of the EPCAM gene, which causes loss of expression of MSH2. These muta­ tions are inherited in an autosomal dominant fashion. The MMR system maintains genomic integrity by correcting base substitution mismatches, and failure of the MMR system results in the accumula­ tion of a thousand-fold more mutations in genes that drive carcino­ genesis compared with MMR-proficient tumors. Lynch syndrome has multiple extracolonic manifestations including increased risk of cancers of the ovary, endometrium, stomach, small bowel, pancreati­ cobiliary system, genitourinary system, brain, and skin. Lynch syndrome may not be associated with multiple polyps and therefore is often unrecognized. Universal testing of colorectal tumors for defects in the MMR system is recommended and accomplished by either immunohistochemistry for MMR proteins in the tumor sample or evaluation for microsatellite instability on the tumor sample. For patients without a Lynch syndrome–associated cancer, family history is the most reliable way to recognize Lynch syndrome, and several family history criteria (Amsterdam Criteria and Revised Bethesda Criteria) have been developed. Germline testing is recommended for all patients with defects in the MMR system noted on the tumor sample or for those non-cancer-affected patients with an appropriate family history. Germline testing should be done in the context of appropriate pre- and posttest genetic counseling. MALIGNANT POTENTIAL ASSOCIATED LESIONS Rare Various congenital abnormalities BRCA1/2 Mutation  The hereditary breast and ovarian cancer syndromes due to mutations in the tumor suppressor genes BRCA1 and BRCA2 may carry an increased risk of colorectal cancer. In particular, BRCA1 mutation may confer a 1.5-fold increased risk of colorectal can­ cer. Currently, the evidence is inconsistent, and therefore, guidelines do not recommend increased screening. Nevertheless, BRCA carriers may have an increased risk of young adult–onset colorectal cancer, and clinicians should be aware of these data. Diet  The etiology for most cases of large-bowel cancer appears to be related to environmental factors. The disease occurs more often in upper socioeconomic populations who live in urban areas. Mortality from colorectal cancer is directly correlated with per capita con­ sumption of calories, meat protein, and dietary fat and oil as well as elevations in the serum cholesterol concentration and mortality from coronary artery disease. Geographic variations in incidence largely are unrelated to genetic differences because migrant groups tend to assume the large-bowel cancer incidence rates of their adopted countries. Furthermore, population groups such as Mormons and Seventh Day Adventists, whose lifestyle and dietary habits differ somewhat from those of their neighbors, have significantly lowerthan-expected incidence and mortality rates for colorectal cancer. The incidence of colorectal cancer has increased in Japan since that nation has adopted a more “Western” diet. At least three hypotheses have been proposed to explain the relationship to diet, none of which is fully satisfactory. ANIMAL FATS  One hypothesis is that the ingestion of animal fats found in red meats and processed meat leads to an increased propor­ tion of anaerobes in the gut microflora (the “microbiome”), resulting in the conversion of normal bile acids into carcinogens. This provoca­ tive hypothesis is supported by several reports of increased amounts of fecal anaerobes (Fusobacterium nucleatum, Bacteroides fragilis) in the stools of patients with colorectal cancer. Diets high in animal (but not vegetable) fats are also associated with high serum cholesterol, which is also associated with enhanced risk for the development of colorectal adenomas and carcinomas. INSULIN RESISTANCE  The large number of calories in Western diets coupled with physical inactivity has been associated with a higher prevalence of obesity. Obese persons develop insulin resistance with increased circulating levels of insulin, leading to higher circulating concentrations of insulin-like growth factor type I (IGF-I). This growth factor appears to stimulate proliferation of the intestinal mucosa. FIBER  Contrary to prior beliefs, the results of randomized trials and case-controlled studies have failed to show any value for dietary fiber or diets high in fruits and vegetables in preventing the recurrence of colorectal adenomas or the development of colorectal cancer. The weight of epidemiologic evidence, however, implicates diet as being the major etiologic factor for colorectal cancer, particularly diets high in animal fat and in calories. ■ ■INFLAMMATORY BOWEL DISEASE (CHAP. 337) Colon and rectal cancers (but not anal cancers) are more common in patients with inflammatory bowel disease (IBD). Most of the data supporting this come from patients with ulcerative colitis. The risk of colorectal cancer in a patient with IBD is relatively small during the first 10 years of the disease but then appears to increase at a rate of ~0.5–1% per year. Cancer may develop in 8–30% of patients. The risk is higher in patients with more extensive, more severe, and longer-lasting colitis. The data are less consistent with Crohn’s disease, but this may be due to the difficulty in distinguishing the two entities and also the different amount of pancolitis in the two diseases. The molecular pathogenesis of colorectal cancer arising from IBD appears to be distinctly different from sporadic cancers. For instance, K-ras and APC mutations appear to be less common in colon cancers arising in IBD patients. Cancer surveillance strategies in patients with IBD are unsatisfac­ tory due to the lack of the classic polyp-to-cancer sequence. Symptoms such as bloody diarrhea, abdominal cramping, and obstruction, which may signal the appearance of a tumor, are similar to the complaints caused by a flare-up of the underlying inflammatory disease. Surveil­ lance for colorectal cancer in patients with IBD is highly technical and requires management by physicians specializing in this area. In patients with longstanding ulcerative colitis, surgical removal of the colon (sub­ total or total) eliminates or significantly reduces the risk of colorectal cancer depending on the extent of the operation. In patients undergo­ ing subtotal colectomy with preservation of the rectum, continued surveillance of the remaining rectum is required. ■ ■OTHER HIGH-RISK CONDITIONS Tobacco Use  Cigarette smoking is linked to the development of colorectal adenomas, particularly after >35 years of tobacco use. No biologic explanation for this association has yet been proposed. Alcohol Use  Moderate to excessive alcohol consumption has been associated with an increased risk of colorectal cancer. It is difficult to tease out the effect compared with other lifestyle risk factors. Obesity, Insulin Resistance, and Diabetes Mellitus  Mul­ tiple studies demonstrate an increased risk of colorectal cancer in obese individuals. Additionally, diabetes is associated with an increased risk of colorectal cancer. This has led to a theory that metabolic syndrome and hyperinsulinemia are risk factors for the development of colorectal cancer. Vitamin D Deficiency  Multiple studies have demonstrated an association between low levels of vitamin D and colon cancer. Never­ theless, no evidence suggests that vitamin D supplementation results in fewer colon cancers. ■ ■PRIMARY PREVENTION Several orally administered compounds have been assessed as possible inhibitors of colon cancer. The most effective class of chemopreventive agents is aspirin and other NSAIDs, which are thought to suppress cell proliferation by inhibiting prostaglandin synthesis. Regular aspirin use as demonstrated in randomized studies reduces the risk of colon adenomas. Regular aspirin use in cohort studies has demonstrated reduced incidence of colon cancer. However, prospective trials using aspirin to prevent colon cancer have had conflicting results in part due to the delayed effects of aspirin on colon carcinogenesis; prevention may increase with the duration and dosage of aspirin, and the effects may take years to manifest. Meta-analyses have suggested that regular aspirin use prevents colon cancer. However, given the potential side effects of aspirin, regular use of aspirin is an individualized decision. Antioxidant vitamins such as ascorbic acid, tocopherols, and β-carotene are ineffective at reducing the incidence of subsequent adenomas in patients who have undergone the removal of a colon adenoma. Estrogen replacement therapy has been associated with a reduction in the incidence of colorectal cancer in women but not mor­ tality from colorectal cancer. ■ ■SCREENING The rationale for colorectal cancer screening programs is that the removal of adenomatous polyps will prevent colorectal cancer and that TABLE 86-3  Screening Strategies for Colorectal Cancer Digital rectal examination Stool testing • Occult blood • Fecal DNA Imaging • Contrast barium enema • Virtual (i.e., computed tomography colonography) Endoscopy • Flexible sigmoidoscopy • Colonoscopy earlier detection of localized, superficial cancers in asymptomatic indi­ viduals will increase the surgical cure rate. It is important to note that screening studies did not take into account the presence of inherited predisposition and germline genetics. Due to the rise in incidence of colorectal cancer in younger adults, the U.S. Preventative Services Task Force updated their screening recommendations in 2021 and lowered the age for recommended screening to 45. Screening strategies for colorectal cancer that have been examined during the past several decades are listed in Table 86-3. CHAPTER 86 The rationale for screening asymptomatic individuals has under­ gone change over many decades, and it is important to understand how that change influences our current approach. Initially, patients were screened for the presence of occult blood in the stool, which would then lead to colonoscopy. Unfortunately, even when performed opti­ mally, the fecal occult blood test has major limitations as a screening technique. About 50% of patients with documented colorectal cancers have a negative fecal occult blood test, consistent with the intermittent bleeding pattern of these tumors. When random cohorts of asymptom­ atic persons have been tested, 2–4% have fecal occult blood–positive stools. Colorectal cancers have been found in <10% of these “test-posi­ tive” cases, with benign polyps being detected in an additional 20–30%. Thus, a colorectal neoplasm will not be found in most asymptomatic individuals with occult blood in their stool. Nevertheless, prospec­ tively controlled trials have shown a statistically significant reduction in mortality rate from colorectal cancer for individuals undergoing annual stool guaiac screening. However, this benefit only emerged after many years of follow-up and was due to colonoscopic intervention, which likely provided the opportunity for cancer prevention through the removal of potentially premalignant adenomatous polyps because the eventual development of cancer was reduced by 20% in the cohort undergoing annual screening. Colorectal Cancer Due to the importance of endoscopic screening in preventing death from colon cancer, many societies shifted from testing stool for the presence of occult blood to offering endoscopic screening for the asymptomatic population. Colonoscopy evaluates the entire colon but is associated with more complications, the need for cathartics to remove stool from the colon, the need for sedation in most cases, and more overall expense. Sigmoidoscopy does not require an enema, is associated with less perforations and morbidity, does not require sedation, and can identify patients at high risk of needing a full colo­ noscopy if polyps or cancer is found in the rectum or sigmoid colon. The recommendation for the inclusion of flexible sigmoidoscopy is strongly supported by randomized studies evaluating a one-time sig­ moidoscopy as opposed to usual standard of care. A reduction in both colorectal cancer incidence and colorectal cancer mortality is obtained for patients undergoing screening, and this effect persists for >15 years. One of the downsides of using screening sigmoidoscopy alone is that in the presence of a normal sigmoidoscopy, ~1.5% of individuals will have either a high-risk polyp or adenocarcinoma in the proximal colon. The issue of missing advanced neoplasms in the proximal colon when using only sigmoidoscopy was addressed by increased frequency of sig­ moidoscopy (every 5 years instead of every 10 years for colonoscopy) and the use of annual fecal immunohistochemical test (FIT) for occult blood. While randomized studies evaluating the combination are lacking, most professional societies offer this approach as an alternative to colonoscopy screening. With the appreciation that the carcinogenic process leading to the progression of the normal bowel mucosa to an adenomatous polyp and then to a cancer is the result of a series of molecular changes, investi­ gators have examined fecal DNA for evidence of mutations associated with such molecular changes as evidence of the occult presence of precancerous lesions or actual malignancies. A multitarget stool DNA test evaluates stool that is collected at home for DNA changes including methylation combined with a FIT test. This multitarget stool DNA test, when done in patients undergoing colonoscopy, has a >90% specificity and sensitivity for detecting a colorectal adenocarcinoma but a <50% sensitivity for detecting an advanced precancerous lesion. The use of imaging studies to screen for colorectal cancers has also been explored. Air contrast barium enemas had been used to identify sources of occult blood in the stool prior to the advent of fiberoptic endoscopy; the cumbersome nature of the procedure and inconve­ nience to patients limited its widespread adoption. The introduction of computed tomography (CT) scanning led to the development of virtual (i.e., CT) colonography as an alternative to the growing use of endoscopic screening techniques. Virtual colonography requires use of colon cathartic bowel preparations and appears to have good accu­ racy at detecting large lesions (>10 mm) but has not been compared in a randomized study with colonoscopy. Two other disadvantages of virtual colonoscopy are that it may have interuser variability and any findings need to be followed up with a colonoscopy requiring a second bowel cathartic preparation. PART 4 Oncology and Hematology Most professional societies agree that screening for colon cancer should begin at age 45 for patients at average risk. In the United States, there is ~60% compliance with screening and the emphasis is on get­ ting patients screened initially with either direct observation using sig­ moidoscopy or colonoscopy or indirect tests such as FIT or multitarget stool DNA. The best combination approach and frequency of screening likely will involve risk stratification factors in the future. ■ ■CLINICAL FEATURES Presenting Symptoms  Symptoms vary with the anatomic loca­ tion of the tumor. Because stool is relatively liquid as it passes through the ileocecal valve into the right colon, cancers arising in the cecum and ascending colon may become quite large without resulting in any obstructive symptoms or noticeable alterations in bowel habits. Lesions of the right colon commonly ulcerate, leading to chronic, insidious blood loss without a change in the appearance of the stool. Consequently, patients with tumors of the ascending colon often pres­ ent with symptoms associated with hypochromic, microcytic anemia, indicative of iron deficiency. As a result, the unexplained presence of iron-deficiency anemia in any adult (with the possible exception of a premenopausal, multiparous woman) mandates a thorough endoscopic and/or radiographic visualization of the entire large bowel (Fig. 86-1). Because stool becomes more formed as it passes into the transverse and descending colon, tumors arising there tend to impede the pas­ sage of stool, resulting in the development of abdominal cramping, occasional obstruction, and even perforation. Radiographs and CTs of the abdomen often reveal characteristic annular, constricting lesions (“apple-core”) (Fig. 86-2). Cancers arising in the rectosigmoid are often associated with hematochezia, tenesmus, and narrowing of the caliber of stool. While these symptoms may lead patients and their physicians to suspect the presence of hemorrhoids, the development of rectal bleeding and/or altered bowel habits demands a prompt digital rectal examination and sigmoidoscopy. Staging, Prognostic Factors, and Patterns of Spread  The prognosis for individuals having colorectal cancer is related to the depth of tumor penetration into the bowel wall and the presence of both regional lymph node involvement and distant metastases. These variables are incorporated into a TNM classification method, in which T represents the depth of tumor penetration, N the presence of lymph node involvement, and M the presence or absence of distant FIGURE 86-1  Double-contrast air-barium enema revealing a sessile tumor of the cecum in a patient with iron-deficiency anemia and guaiac-positive stool. The lesion at surgery was a stage II adenocarcinoma. metastases (Fig. 86-3). Superficial lesions that do not involve regional lymph nodes and do not penetrate through the submucosa (T1) or the muscularis (T2) are designated as stage I (T1–2N0M0) disease; tumors that penetrate through the muscularis but have not spread to lymph nodes are stage II disease (T3–4N0M0); regional lymph node involve­ ment defines stage III (TXN1–2M0) disease; and metastatic spread to sites such as liver, lung, or bone indicates stage IV (TXNXM1) disease. Unless gross evidence of metastatic disease is present, disease stage cannot be determined accurately before surgical resection and patho­ logic analysis of the operative specimens. The majority of recurrences occur within the initial 5 years after resection. Occasionally tumors can recur between 5 and 10 years after resection, and this appears to be more common with rectal cancer FIGURE 86-2  Annular, constricting adenocarcinoma of the descending colon. This radiographic appearance is referred to as an “apple-core” lesion and is always highly suggestive of malignancy. Stage I II T1 T2 No deeper than submucosa Not through muscularis Extent of tumor >90% 5-year survival >95% 23% Colon Stage at presentation Rectal 34% Mucosa Muscularis mucosa Submucosa Muscularis propria Serosa Fat Lymph nodes FIGURE 86-3  Staging and prognosis for patients with colorectal cancer. than colon cancer. The likelihood for 5-year survival in patients with colorectal cancer is stage-related (Fig. 86-3), and the survival rates per stage have been improving in the past several decades. The most plau­ sible explanation for improved survival is the more thorough evalua­ tion for metastatic disease and the positive effects of chemotherapy for treatment of adjuvant and systemic disease. A minimum of 12 sampled lymph nodes is thought necessary to accurately define tumor stage, and the more nodes examined, the better reliability that a patient is either node negative or node positive. Other predictors of a poor prog­ nosis after a total surgical resection include tumor penetration through the bowel wall into pericolic fat, poorly differentiated histology, per­ foration and/or tumor adherence to adjacent organs (increasing the risk for an anatomically adjacent recurrence), and venous invasion by tumor (Table 86-4). Tumors with microsatellite instability or defects in MMR have improved prognosis presumably due to an enhanced immune response against the tumor. Tumors arising in the left colon are associated with a better prognosis than those appearing in the right colon, likely due to differences in molecular patterns. In contrast to most other cancers, the prognosis in colorectal cancer is not influenced by the size of the primary lesion when adjusted for nodal involvement and histologic differentiation. Colorectal cancer generally spreads to the liver, lungs, and peritoneal cavity. The liver represents the most frequent visceral site of metastasis; it is the initial site of distant spread in one-third of recurring colorectal TABLE 86-4  Predictors of Poorer Outcomes Following Total Surgical Resection of Colorectal Cancer Tumor spread to regional lymph nodes Number of regional lymph nodes involved Tumor penetration through the bowel wall Poorly differentiated histology Perforation Tumor adherence to adjacent organs Venous invasion Preoperative elevation of CEA titer (>5 ng/mL) Specific chromosomal deletion (e.g., mutation in the b-raf gene) Right-sided location of primary tumor Abbreviation: CEA, carcinoembryonic antigen. Staging of colorectal cancer III IV N1 N2 M T3 ≥4 lymph node metastases 1–3 lymph node metastases Distant metastases Through muscularis 50–70% 25–60% <5% 70–85% 26% 20% 31% 26% 15% 25% CHAPTER 86 Colorectal Cancer cancers and is involved in more than two-thirds of such patients at the time of death. It can spread to the brain and bones but not typically as an initial site of metastatic disease, but rather after years of having systemic metastases. Nevertheless, prompt evaluation of signs and symptoms of bone and brain involvement should be efficiently done because lack of prompt treatment can have devastating consequences (e.g., cord compression, brain hemorrhage). TREATMENT Colorectal Cancer Staging should consist of a complete blood count, comprehensive metabolic panel, serum carcinoembryonic antigen (CEA), and a chest, abdomen, and pelvic CT scan. Additional imaging such as magnetic resonance imaging (MRI) and positron emission tomog­ raphy (PET) scan can be dependent on the findings of the CT scan. When possible, a colonoscopy of the entire large bowel should be performed to identify synchronous neoplasms and/or polyps. While surgical resection is the standard of care for cure in patients with localized disease, initial treatment of colorectal cancer when possible should be delayed until MMR status or microsatellite sta­ bility status is known. MSI-high rectal cancers can be treated for cure with checkpoint inhibitors (PD-1 antibodies) without the need for surgery, radiation, and chemotherapy. Studies are underway involving management of MSI-high colon cancers with checkpoint inhibition. LOCALIZED COLON CANCER For the vast majority of patients with MSS colon adenocarcinoma, initial surgical resection is the standard of care. Surgery with minimally invasive techniques such as laparoscopy and robotic approaches has largely replaced open approaches. Following com­ plete surgical resection, patients with stage I disease are considered cured. Patients with high-risk stage II and stage III colon cancer are considered for the appropriateness of adjuvant chemotherapy. The standard adjuvant approaches generally improve overall survival and cure rates by ~30%. Adjuvant chemotherapy for 3–6 months either with single-agent fluoropyrimidine (IV or oral) or in combination with oxaliplatin is considered the standard adjuvant treatment for MSS colon cancer. Following recovery from a complete resection, patients should be observed carefully for 5 years using physical examinations and blood chemistry measurements at regular intervals. Some authorities favor measuring plasma CEA levels at 3-month inter­ vals because of the sensitivity of this test as a marker for otherwise undetectable tumor recurrence. The value of periodically assessing plasma for the presence of circulating tumor DNA as a biomarker for residual or recurrent disease is under study. Subsequent endo­ scopic surveillance of the large bowel 1 year after resection and then usually every 3 years is indicated because patients who have been cured of one colorectal cancer have a 3–5% probability of develop­ ing an additional bowel cancer during their lifetime and a >15% risk for the development of adenomatous polyps. Anastomotic (“sutureline”) recurrences are infrequent in colorectal cancer patients, provided the surgical resection margins were adequate and free of tumor. The value of periodic CT scans of the abdomen, assess­ ing for an early, asymptomatic indication of tumor recurrence, is uncertain; however, CT has been recommended semi-annually to annually for the first 3 postoperative years. LOCALIZED RECTAL CANCER For the vast majority of patients with MSS rectal adenocarcinoma, surgical resection is considered the standard curative therapy. In addition to the staging above, pelvic MRI should be standard in staging for all patents with rectal cancer to assess mesorectal mar­ gin and nodal status. Surgical resection can either be a low anterior resection (LAR) or an abdominal-perineal resection (APR). An APR requires a permanent colostomy due to resection of the anal sphincter. Unlike colon cancer, rectal cancers (defined as tumor at or below the peritoneal reflection) have an increased risk of local recurrence after surgery. The risk of local recurrence increases with stage and closeness to the mesorectal border and decreases with distance from the anus. Thus, tumors requiring an APR have a high risk of local recurrence. The risk of local recurrence can be reduced with preoperative chemotherapy and radiation. Patients with stage II and III rectal cancer are deemed to have a risk high enough to warrant consideration of preoperative therapy. PART 4 Oncology and Hematology Two new treatment paradigms have emerged for patients with rectal cancer in specific circumstances. The first situation involves patients in whom the consequences of radiation therapy are deemed unacceptable. Radiation is associated with the potential long-term side effects of radiation proctitis (increased risk in patients with IBD), small-bowel obstruction to adhesions, and malignancy (~1% risk after 10 years). Notably, radiation therapy in women causes infertility due to the effects of radiation on the uterus even when the ovaries are not included in the radiation field. Preoperative therapy with a fluo­ ropyrimidine and oxaliplatin followed by surgical resection produces similar rates of local control to preoperative chemoradiation and can be considered for average-risk stage II and III rectal cancer patients. The second circumstance involves patients with stage II and III rectal cancer treated with total preoperative therapy who experience a complete clinical response. Nonoperative management can be considered in these patients because 60–70% will be cured without an LAR or APR. It is important to note that 30–40% of patients will experience a recurrence so patients need to be followed intensively in the years following chemotherapy and radiation. The majority of patients who experience a local recurrence during nonoperative management can be cured with surgery. METASTATIC COLORECTAL CANCER The first principle to note is that complete resection of metastatic disease is considered curative for patients with colorectal cancer, particularly in the setting of metastases isolated to one site (liver, lungs, peritoneum). Consultation with the appropriate surgical spe­ cialists is preferred before starting systemic chemotherapy. The detection of metastases should not preclude surgery to remove the primary tumor in patients with tumor-related symp­ toms such as gastrointestinal bleeding or obstruction but usually prompts the initiation of chemotherapy unless those symptoms are viewed to be life-threatening. Studies have demonstrated that resec­ tion of the primary tumor in the setting of unresectable metastatic disease does not improve overall survival and should be done only on an ad hoc basis. Patients with MSI-high colon cancer should be treated with a checkpoint inhibitor as initial treatment. Long-term survival is pos­ sible in these patients, and some will have a complete response and may not ever have recurrence of their cancer. For the vast majority of patients with MSS colorectal adenocarcinoma who are not can­ didates for complete resection of metastatic disease, treatment with systemic chemotherapy is associated with marked improvement in overall survival compared with palliative care alone. A patient with metastatic disease lives on average for 2–3 years with systemic che­ motherapy, and as many as 25% of patients will live for at least 5 years on and off chemotherapy. The mainstays of therapy for patients with metastatic colon cancer are the following medications: 5-fluorouracil (5-FU; or capecitabine), irinotecan, oxaliplatin, and bevacizumab. These medications are used in combination all together (e.g., FOLIR­ INOX-bevacizumab or FOLFOXIRI-bevacizumab) or in partial combination (e.g., FOLFOX-bevacizumab, FOFIRI-bevacizumab). 5-FU is an inhibitor of thymidylate synthase and is used in con­ junction with folinic acid (leucovorin). It is metabolized by dihy­ dropyrimidine dehydrogenase (DPD), which is deficient in ~1% of adults. Individuals with DPD deficiency can experience increased side effects from 5-FU, especially myelosuppression and mucositis. Testing for DPD gene mutations may identify patients at high risk of DPD deficiency and toxicity from 5-FU. Irinotecan is a topoi­ somerase I inhibitor and is metabolized by glucuronidation in the liver. Thus, patients with UGT mutations can experience decreased clearance and enhanced toxicity, principally myelosuppression. Oxaliplatin is a platinum analogue that is metabolized generally and can cause permanent peripheral neuropathy. Bevacizumab is a monoclonal antibody against vascular endothelial growth fac­ tor (VEGF). Side effects of bevacizumab include hypertension, nephrotic syndrome, and impaired wound healing. Untreated hypertension from bevacizumab has been associated with posterior reversible leukoencephalopathy syndrome. Other agents with proven disease-altering effects in the meta­ static setting include trifluridine-tipiracil, regorafenib, and fruquin­ tinib. Trifluridine is a nucleoside analogue that is used with tipiracil, a thymidine phosphorylase inhibitor. Regorafenib is an oral multi­ targeted tyrosine kinase inhibitor, including VEGF. Fruquintinib is an oral VEFG tyrosine kinase inhibitor. Molecular genotyping of the primary tumor should be done in all patients with metastatic colon cancer if possible. Patients without mutations of the RAS/RAF pathway can have excellent responses and prolonged survival with the addition of antibodies against epi­ dermal growth factor (EGF), such as cetuximab and panitumumab. These agents are often given in combination with either FOLFOX or FOLFIRI. The effect of cetuximab and panitumumab appears to be limited to left-sided colon cancers because right-sided colon cancers have upregulation of receptor tyrosine kinases that create resistance to these antibodies. The main side effects of these two antibodies are the class effects of diarrhea and acneiform rash. Cetuximab, which is partially murine, is also associated with aller­ gic reactions. Patients who harbor BRAF V600E mutations may have a particu­ larly virulent form of colon cancer that does not respond as well to standard chemotherapy. These mutations tend to occur more com­ monly in right-sided tumors and women. They often involve meth­ ylation of MLH1 and can be MMR deficient. The BRAF inhibitor encorafenib is approved for use with cetuximab in patients with BRAF-mutant colorectal cancer. HER2 overexpression can be seen in colorectal cancer, and con­ sideration of anti-HER2–targeted therapy is warranted. Tucatinib (HER2 tyrosine kinase inhibitor) and trastuzumab (anti-HER2 monoclonal antibody) are approved in the United States for patients with HER2-positive colorectal cancers that lack a RAS mutation. # 16 - 87 Tumors of the Liver and Biliary Tree ### 87 Tumors of the Liver and Biliary Tree Rarely, RET fusions and TRK fusions can be seen in patients with metastatic colorectal cancer. These patients can have tremendous responses to the appropriate RET and TRK inhibitors with marked prolongation of survival. CANCERS OF THE ANUS Cancers of the anus account for 1–2% of the malignant tumors of the large bowel. Anal cancer by convention refers to squamous cell carci­ nomas arising in the anorectal region. Other types of cancers including melanoma, neuroendocrine cancer, lymphoma, and mesenchymal tumors can arise in these regions but are referred to by their histologic subtype and are not the subject of this chapter. True adenocarcinomas arising from the glands in the anal canal that are distinct from rectal adenocarcinoma can also arise but, for all intents and purposes, are indistinguishable from rectal adenocarcinoma and treated accordingly. Most anal cancers arise in the anal canal, the anatomic area extend­ ing from the anorectal ring to a zone approximately halfway between the pectinate (or dentate) line and the anal verge. The dentate line can be quite variable in adults but, on average, is 4 cm from the anal verge. Squamous cell carcinomas are characterized as either nonkeratinizing or keratinizing. Older terms such as cloacogenic and basaloid are not used anymore, and these tumors are instead characterized as nonkera­ tinizing. Outcomes for keratinizing and nonkeratinizing squamous cell carcinoma of the anus are not different. The development of anal cancer is associated with infection by human papillomavirus (HPV), the same virus etiologically linked to cervical and oropharyngeal cancers. The same HPV subtypes associ­ ated with cervical cancer are seen in anal cancer. The infection may lead to squamous intraepithelial lesions (SILs), which are classified as either low grade (LSIL) or high grade (HSIL). LSILs are associated with non–cancer-causing HPV subtypes, are not considered precancerous, and can spontaneously regress. HSILs are associated with HPV16 and are considered precancerous. Anal cancer risk is increased in both men and women with immunocompromised states including solid organ transplant patients, patients with chronic immunosuppression with glucocorticoids, and patients living with HIV, particularly with low CD4 counts. Anal cancers occur most commonly in middle-aged per­ sons and are more frequent in women than men. At diagnosis, patients may experience bleeding, pain, sensation of a perianal mass, and pru­ ritus. Examination of and attention to the inguinal lymph nodes on imaging is important because anal cancers often spread initially to the inguinal region rather than the iliac nodes like rectal cancer. The standard treatment for anal cancers consists of 5-FU, mitomy­ cin, and concurrent external beam radiation therapy. The majority of patients will experience a complete response to therapy. Some patients will have ongoing resolution of their cancer over the 6 months after completion of therapy. Therefore, the decision about whether a patient has had a complete response to therapy is not made until after 6 months following chemoradiation. Patients who are considered primarily refractory to chemoradiation or those with locally recurrent disease can be cured with radical resec­ tion (i.e., APR). In addition to those experiencing a local recurrence, ~10% of patients may experience continued rectal incontinence due to the effects of radiation therapy and undergo a subsequent colostomy. Metastatic anal cancer is considered incurable. It may respond well to carboplatin and paclitaxel. PD-1 antibodies have limited activity in patients with metastatic disease. Acknowledgment Robert J. Mayer contributed to this chapter in the prior edition and material from that chapter has been retained here. ■ ■FURTHER READING André T et al: Pembrolizumab in microsatellite-instability-high advanced colorectal cancer. N Engl J Med 383:2207, 2020. Cercek A et al: PD-1 blockade in mismatch repair-deficient locally advanced rectal cancer. N Engl J Med 386:2363, 2022. Colón-López V et al: Anal cancer risk among people with HIV infec­ tion in the United States. J Clin Oncol 36:68, 2018. Dekker E et al: Colorectal cancer. Lancet 394:1467, 2019. Eng C et al: Anal cancer: emerging standards in a rare disease. J Clin Oncol 40:2022. Grothey A et al: Duration of adjuvant chemotherapy for stage III colon cancer. N Engl J Med 378:1177, 2019. Inadomi JM: Screening for colorectal neoplasia. N Engl J Med 376:149, 2017. Long H et al: Pathways of colorectal carcinogenesis. Gastroenterology 158:291, 2020. Petrelli F et al: Prognostic survival associated with left-sided vs right-sided colon cancer. A systemic review and meta-analysis. JAMA Oncol 3:211, 2017. Schrag D et al: Preoperative treatment of locally advanced rectal cancer. N Engl J Med 389:1631, 2023. Siegel RL et al: Colorectal cancer statistics 2024. CA Cancer J Clin 12:49, 2024. Josep M. Llovet Tumors of the Liver and Biliary Tree CHAPTER 87 Tumors of the Liver and Biliary Tree Liver cancer is the sixth most common cancer worldwide, the third leading cause of cancer-related deaths and the leading cause of death among cirrhotic patients. Liver cancer comprises a heterogeneous group of malignant tumors that range from hepatocellular carcinoma (HCC; ~85 cases), intrahepatic cholangiocarcinoma (iCCA; ~10%), and other malignancies, such as fibrolamellar HCC, mixed HCCiCCA, epithelioid hemangiothelioma, and the pediatric cancer hepato­ blastoma. The burden of liver cancer is increasing globally. HEPATOCELLULAR CARCINOMA ■ ■EPIDEMIOLOGY AND RISK FACTORS Overall, liver cancer accounts for 7% of all cancers (~900,000 new cases each year), and HCC represents 85% of primary liver cancers. The highest incidence rates of HCC occur in Asia and sub-Saharan Africa due to the high prevalence of hepatitis B virus (HBV) infection, with 20–35 cases per 100,000 inhabitants. Southern Europe and now North America have intermediate incidence rates (10 cases per 100,000), whereas Northern and Western Europe have low incidence rates of less than 5 cases per 100,000 inhabitants. In the United States, the incidence of liver cancer is 40,000 cases per year (Fig. 87-1). HCC has a strong male preponderance, with a male-to-female ratio estimated to be 2.5:1. The incidence increases with age, reaching a peak at 65–70 years old. In Chinese and in black African populations (where vertical transmis­ sion of HBV occurs), the mean age is 40–50 years. By contrast, in Japan mean age in men is now around 75 years. The main risk factors for HCC development are cirrhosis—an asso­ ciated chronic liver damage caused by inflammation and fibrosis—of any etiology, chronic infection by HBV or hepatitis C virus (HCV) infection, alcohol abuse, metabolic syndrome, and hemochromatosis (associated to HFE1 gene germline mutations) (Fig. 87-1). Cirrhotic patients represent 1% of the human population, and one-third of them will develop HCC during their lifetime. Long-term follow-up studies have established an annual risk of HCC development of 3–8% in HBV- or HCV-infected cirrhotic patients. HCC is less common (1–2% per year) in cirrhosis associated with alcohol, metabolic dysfunction– associated steatohepatitis (MASH, formerly known as nonalcoholic steatohepatitis or NASH), α1-antitrypsin deficiency, autoimmune hepa­ titis, Wilson’s disease, and cholestatic liver disorders. Predictors of liver cancer development among cirrhotic patients have been associated Central Europe Western Europe North America Western Africa Andean Latin America South Latin America ASR (World) per 100,000 ≥8.4 5.8–8.4 4.7–5.8 3.3–4.7 PART 4 Oncology and Hematology Not applicable No data <3.3 FIGURE 87-1  Distribution of hepatocellular carcinoma (HCC) incidence according to geographical area and etiology. HBV, hepatitis B virus; HCV, hepatitis C virus; NASH, nonalcoholic steatohepatitis. (Reproduced with permission from JM Llovet et al: Hepatocellular carcinoma. Nat Rev Disease Primers 21:76, 2021.) with liver disease severity (platelet count of <100,000/µL, presence of portal hypertension), the degree of liver stiffness as measured by transient elastography, and liver gene signatures capturing the cancer field effect. In terms of attributable risk fraction, HBV infection—a DNA virus that can cause insertional mutagenesis and affects ~300 million people globally—accounts for ~50% of HCC cases globally (60% in Asia and Africa and 20% in the Western world). Among patients with HBV infection, a family history of HCC, HBeAg seropositivity, high viral load, and genotype C are independent predictors of HCC development. HCV infection—an RNA virus that affects ~70 million people—is responsible for ~30% of cases and is the main cause of HCC in Europe and North America. Among patients with HCV infection, HCC occurs almost exclusively when relevant advanced liver damage and fibrosis are present, particularly if associated with HCV genotype 1b. Alcohol consumption and metabolic syndrome due to diabetes and obesity are responsible for ~30% of cases. MASH is the fastest grow­ ing cause of cirrhosis in developed countries and currently represents ~15–20% of HCC cases in the West. The annual incidence of HCC in MASH-related cirrhosis (1–2%/year) justifies including cirrhotic patients in surveillance programs. Nonetheless, it has to be taken into account that 25–30% of MASH-associated HCCs occur in the absence of cirrhosis. A PNPLA3 polymorphism is strongly associated with fatty and alcoholic chronic liver diseases and HCC occurrence. Finally, other cofactors contributing to HCC development in all etiologies are tobacco, aflatoxin B1 (a fungal carcinogen present in food supplies that induces TP53 mutations), and aristolochic acid contained in Chinese medicine herbs. ■ ■MOLECULAR PATHOGENESIS HCC development is a complex multistep process that starts with precancerous cirrhotic nodules, so-called low-grade dysplastic nodules (LGDN) that evolve to high-grade dysplastic nodules (HGDN) that can transform into early-stage HCC. Molecular studies support the pivotal role of adult hepatocytes as the cell of origin, either by directly transforming to HCC or by de-differentiating into hepatocyte precur­ sor cells. Alternatively, progenitor cells also give rise to HCC with progenitor markers. Genomic analysis has provided a clear picture of the main drivers responsible for HCC initiation and progression. This tumor results Eastern Europe Japan East Asia South-East Asia North Africa, Middle East Oceania Etiology HCV Alcohol HBV Southern Africa NASH & other from the accumulation of around 40–60 somatic genomic alterations per tumor, among which 4–8 are considered driver cancer genes. HCC is a prototypical inflammation-associated cancer, where immune microenvironment and oxidative stress present in chronically damaged livers play pivotal roles in inducing mutations. In preneoplastic HGDN, mutations in telomere reverse transcriptase (TERT) gene (20% of cases) and gains in 8q have been described. Oncogenic transformation occurs upon additional genomic hits. The main molecular drivers of HCC are in the telomerase reverse transcriptase (TERT) promoter (56%), TP53 (27%), and CTNNB1 (26%), all of which are unactionable with molecular therapies. Genes commonly mutated in other solid tumors such as EGFR, HER2, PIK3CA, BRAF, or KRAS are rarely mutated in HCC (<5%) (Table 87-1). Studies assessing copy-number alterations in HCCs have consistently identified: (1) high-level amplifications at 5–10% prevalence containing oncogenes in 11q13 (CCND1 and FGF19) and 6p21 (VEGFA), TERT focal amplification, and homozygous dele­ tion of CDKN2A; and (2) common amplifications containing MYC (8q gain). Overall, only ~20–25% of HCCs have at least one actionable mutation. Some risk factors have been associated with specific molecu­ lar aberrations. HBV integrates into the genome of driver genes, such as the TERT promoter, MLL4, and cyclin E1 (CCNE1). Alcohol abuse and HCV infection have been associated with CTNNB1 mutations. TP53 mutations are the most frequent alterations with a specific hotspot of mutation (R249S) in patients with aflatoxin B1 exposure. Molecular and Immune Classes  Genomic studies have revealed two molecular subclasses of HCC, each representing ~50% of patients. The proliferative subclass associated with poor outcomes, HBV-related etiologies, and overexpression of α-fetoprotein is enriched by activa­ tion of Ras, mammalian target of rapamycin (mTOR), and insulin-like growth factor (IGF) signaling and FGF19 amplification. By contrast, the so-called nonproliferative subclass contains a subtype character­ ized by CTNNB1 mutations and better outcome. Another classification based upon immune status has been proposed. It defines an inflamed HCC class in ~35% of cases (i.e., hot tumors), characterized by immune infiltrate with expression of PD-1/PD-L1, enrichment of T-cell activa­ tion, and better response to immunotherapies, and a noninflamed class (cold tumors), which includes the excluded subclass associated with activation of pathways related with immune escape (i.e., Wnt signal­ ing) or absence of T-cell infiltrate. None of this molecular knowledge TABLE 87-1  Molecular Aberrations Common in Hepatocellular Carcinoma (HCC)a PATHWAY TARGET PREVALENCE (%) Mutations Telomere stability TERT promoter p53/cell cycle control TP53 ATM RB1 Wnt/β-catenin signaling CTNNB1 AXIN1 Chromatin remodeling ARID1A ARID2 KMT2A KMT2C Ras/PI3K/mTOR pathway RPS6KA3 TSC1/TSC2 Oxidative stress NFE2L2 KEAP1 High-level focal amplifications VEGF signaling VEGFA FGF signaling FGF19 Cell-cycle control CCND1 protein Target with homozygous deletion TP53/cell-cycle control CDKN2A TP53 Retinoblastoma 1 Wnt/β-catenin signalling AXIN1 aRecurrent mutations, focal amplifications, or homozygous deletions in HCC based on next-generation sequencing analyses. has yet been translated into actual clinical benefits for any specific molecularly based subgroups, and thus, precision oncology is still an unmet goal of therapy. ■ ■PREVENTION AND EARLY DETECTION Prevention  Primary prevention of HCC can be achieved by vac­ cination against HBV and effective treatment of HBV and HCV infec­ tion. Universal vaccination against HBV infection is associated with a significant decrease of the incidence of HCC. Nowadays, HBV vaccina­ tion is recommended to all newborns and high-risk groups, following World Health Organization guidelines, and people with risk factors for acquiring HBV infection, such as health workers, travelers to areas where HBV infection is prevalent, injecting drug users, and people with multiple sex partners. Effective antiviral treatments for patients with chronic HBV infection— achieving undetectable viral titers (circulating HBV-DNA)—result in 50–80% risk reduction of HCC development. Treatment of HCV with direct-acting antiviral agents (DAAs) yields >90% sustained virological response (SVR) rates after 12 weeks of treatment, thus significantly reducing HCC occurrence. Once cirrhosis is established, the incidence of HCC is lower for patients with SVR than for those with active viral disease, although they continue to have persistent HCC risk. Clinical practice guidelines recommend coffee consumption as a preventive strategy in patients with chronic liver disease. Aspirin, statins, and metformin have shown preventive effects but are not yet recommended as formal chemopreventive strategies. Surveillance  Surveillance programs aim to reduce cancer-related mortality. This is usually achieved through early detection that enhances the applicability and cost-effectiveness of curative therapies. U.S. and European guidelines recommend surveillance for patients at high risk for HCC on the basis of cost-effectiveness analyses. Surveillance is recommended for cirrhotic patients owing to any cause, those with HCV-related advanced fibrosis, and patients with chronic HBV infection if Asian aged >40 years, African aged >20 years, family history of HCC, or patients with sufficient risk by risk scores such as PAGE-B. In terms of liver dysfunction, the presence of advanced cirrhosis (Child-Pugh class C) prevents potentially curative therapies from being employed, and thus surveillance is not recom­ mended. As an exception, patients on the waiting list for liver trans­ plantation, regardless of liver functional status, should be screened for HCC in order to detect tumors exceeding conventional criteria and to define priority policies for transplantation. Ultrasonography every 6 months with serum α-fetoprotein (AFP) levels is the recommended method of surveillance. It has a sensitivity of ~65% and a specificity of >90% for early detection. A shorter followup interval (every 3–6 months) is recommended when a nodule of <1 cm has been detected. Computed tomography (CT) and magnetic resonance imaging (MRI) are not recommended as screening tools due to lack of data on accuracy, high cost, and possible harm (i.e., radiation with CT). Contrast-enhanced MRI can be considered in patients with obesity and fatty liver, where visualization with ultrasound is subopti­ mal. The accuracy of other serum biomarkers proposed, such as des-γ carboxyprothrombin (DCP) and the L3 fraction of AFP (AFP-L3), in early detection is not known. CHAPTER 87 Despite the fact that surveillance is cost-effective in HCC, the global implementation of such programs is estimated to engage ~50% of the target population in Europe and ~30% in the United States. Public health policies encouraging the implementation of such programs could lead to an increase in early tumor detection. Tumors of the Liver and Biliary Tree Diagnosis  HCC is generally diagnosed at early or intermediate stages in Western countries but at advanced stages in most Asian (except Japan) and African countries. A surveillance program yields detection of early HCC in 70–80% of cases. At these stages, the tumor is asymptomatic, and diagnosis can be made by noninvasive (radiological) or invasive (biopsy) approaches. Without surveillance, HCC is discovered either as a radiological finding or due to cancerrelated symptoms. If symptoms are present, the disease is already at an advanced stage, with a median life expectancy of <1 year. Symptoms include malaise, weight loss, anorexia, abdominal discomfort, or signs related to advanced liver dysfunction. NONINVASIVE (RADIOLOGICAL) DIAGNOSIS  Patients enrolled in a surveillance program are diagnosed by identification of a new liver nodule on abdominal ultrasound. Noninvasive criteria can only be applied to cirrhotic patients and are based on imaging techniques obtained by four-phase multidetector CT scan (four phases are unen­ hanced, arterial, venous, and delayed) or dynamic contrast-enhanced MRI. A flowchart of diagnosis and recall policy recommended by U.S. and European guidelines is summarized in Fig. 87-2. In nodules >1 cm or with AFP ≥20 ng/mL or rising AFP, multiphasic contrast-enhanced CT or MRI is recommended. Using these techniques, the typical hall­ mark of HCC consists of vascular uptake of the nodule in the arterial phase with washout in the portal venous or delayed phases. This radio­ logical pattern captures the hypervascular nature characteristic of HCC and has a diagnostic specificity of ~95–100%, making a biopsy unnec­ essary. The Liver Imaging Reporting and Data System (LI-RADS) has been proposed as a way of classifying radiological findings. Essentially, nodules >10 mm visible on multiphase exams are assigned category codes reflecting their relative probability of being benign, HCC, or other hepatic malignant neoplasm. LI-RADS-1 lesions have a 0% prob­ ability of HCC, whereas lesions assigned to the LI-RADS-4 category are likely to be an HCC in 60–70% of cases and repeated imaging within 3–6 months or biopsy is recommended. Finally, LI-RADS-5 lesions have a ~95% probability of being HCCs. LI-RADS-M category comprises lesions that have malignant radiological features but are only HCC in ~35% of cases. Nodules <1 cm in size are unlikely to be HCC and would be very difficult to diagnose, and thus ultrasound follow-up at 3–4 months is recommended. Contrast-enhanced ultrasound (CEUS) and angiography Mass/Nodule on US >1 cm, AFP ≥20 ng/mL or rising AFP <1 cm Repeat US at 3–6 mos Growing/changing pattern 1 positive technique HCC radiological hallmark or LI-RADS 5* Stable LI-RADS 4 LI-RADS 3 Use alternative imaging PART 4 Oncology and Hematology Inconclusive *Hallmark of HCC: Contrast uptake in arterial phase and washout in venous or delayed phase **Consider a second biopsy in case of inconclusive FIGURE 87-2  Recall diagnosis schedule for HCC (EASL). EASL, European Association for the Study of Liver Disease; HCC, hepatocellular carcinoma. (Modified with permission from EASL. J Hepatology 69:182, 2018.) are less accurate for HCC diagnosis. Positron emission tomography (PET) scan performs poorly for early diagnosis. AFP levels ≥400 ng/dL are highly suspicious but not diagnostic of HCC according to guidelines. PATHOLOGICAL DIAGNOSIS  Pathological diagnosis is required: (1) in patients without cirrhosis, (2) if radiology is not typical in at least one of two imaging techniques (CT and MRI), and (3) for a LI-RADS-4 lesion. Biopsy has not been used as the gold standard in clinical prac­ tice, although with the advent of molecular therapies, some guidelines advocate obtaining tissue samples in the setting of all research stud­ ies in HCC, even if radiological criteria are met. Sensitivity of liver biopsies ranges between 70 and 90% for all tumor sizes but decreases to <50% in tumors 1–2 cm in size. The risk of complications, such as tumor seeding and bleeding, after liver biopsy is ~2–3%. Biopsies should be assessed by an expert hepatopathologist. The use of special stains may help to resolve diagnostic uncertainties. Positive staining in two of four markers (glypican 3 [GPC3], glutamine synthetase, heat shock protein 70 [HSP70], and clathrin heavy chain) is highly specific for HCC. Additional staining can be considered to detect progenitor cell features (K19 and epithelial cell adhesion molecule [EpCAM]) or assess neovascularization (CD34). A negative biopsy does not elimi­ nate the diagnosis of HCC. A second biopsy is recommended in case of inconclusive findings or growth or change in enhancement pattern identified during follow-up (Fig. 87-2). ■ ■TREATMENT Overview  The landscape of management of HCC has substan­ tially changed during the last decade. For early stages, resection, liver transplantation, and local ablation have substantially improved life expectancy, with median overall survival (OS) times beyond 5 years (Fig. 87-3). Adjuvant therapy with atezolizumab plus bevacizumab improves recurrence-free survival in patients at high risk of recurrence undergoing resection or ablation. For intermediate stages, transarterial chemoembolization (TACE) has improved the natural history of 16 Four-phase contrast-enhanced CT or Multiphasic contrast-enhanced/or gadoxetic-enhanced MRI Yes HCC Biopsy** Benign or non-HCC malignant months to ~30 months, and when combined with durvalumab plus bevacizumab, it improves progression-free survival. Systemic drugs for advanced tumors (atezolizumab plus bevacizumab, durvalumab plus tremelimumab, sorafenib, lenvatinib, regorafenib, cabozantinib, and ramucirumab) have improved median survivals from 8 months to even beyond 19 months in front-line and to 10 months in second-line treatment (Fig. 87-3). Staging Systems and Treatment Allocation  Staging systems are aimed at stratifying patients according to prognostic factors and out­ come and allocating the best available therapies according to evidence. The most accepted staging system is the Barcelona Clinic Liver Cancer (BCLC) Classification, which is endorsed by U.S. and European clinical practice guidelines (Fig. 87-3). This staging system defines five prog­ nostic subclasses and allocates specific treatments for each stage. The BCLC staging system has been externally validated by numerous stud­ ies. It is an evolving system that allows incorporation of new therapies and treatment-dependent variables as new evidence emerges. Several treatments improve survival in HCC, and thus have been incorporated in the therapeutic algorithm: surgical resection, liver transplanta­ tion, radiofrequency (RF) ablation, microwave, chemoembolization, and systemic therapies (atezolizumab-bevacizumab, durvalumab plus tremelimumab, sorafenib, lenvatinib, regorafenib, cabozantinib, and ramucirumab). The BCLC assigns each patient to a given treatment allocation. Treatment stage migration is also applied by this scheme, meaning that if patients are not candidates for the selected therapy, the next effective therapy at more advanced stages can be given. In HCC, three parameters are relevant for defining treatment strat­ egy: tumor status, cancer-related symptoms, and liver dysfunction. The BCLC staging captures all three variables and allocates patients to treatments according to evidence. Since >80% of patients have two diseases, HCC and cirrhosis, a clear measurement of liver dysfunction should be in place. The prognosis of chronic liver disease is com­ monly assessed using the Child-Pugh score, which uses five clinical Hepatocellular carcinoma Very early (BCLC 0) Early (BCLC A) Stages Stratification Treatment - Single nodule ≤2 cm - Child-Pugh A, ECOG 0 - Single or ≤3 nodules ≤3 cm - Child-Pugh A-B, ECOG 0 2–3 nodules ≤3 cm Solitary Yes Optimal surgical candidate No Yes Transplant candidate No Transplantation (LT) Ablation First choice# Second choice## Ablation Resection Systemic therapy* Best supportive care Downstaging LT TACE (TARE, SBRT) Extended criteria LT (TARE) Resection Expected outcomes Median OS: 10 yr Transplantation; >6 yr for resection/ablation FIGURE 87-3  Staging system and therapeutic strategy. BCLC classification comprises five stages that select the best candidates for therapies according to evidence-based data. Patients with asymptomatic early tumors (stages 0 -A) are candidates for radical therapies (resection, transplantation, or local ablation). Asymptomatic patients with multinodular HCC (stage B) are suitable for transcatheter arterial chemoembolization (TACE), whereas patients with advanced symptomatic tumors and/or an invasive tumoral pattern (stage C) are candidates to receive systemic therapies. End-stage disease (stage D) includes patients with poor prognosis that should be treated by best supportive care. BCLC, Barcelona Clinic Liver Cancer; DDLT, deceased donor liver transplantation; EASL, European Association for the Study of Liver Disease; ECOG, Eastern Cooperative Oncology Group Performance Status; EORTC, European Organisation for Research and Treatment of Cancer; GRADE, grading of recommendations assessment, development, and evaluation; HCC, hepatocellular carcinoma; LDLT, living donor liver transplantation; OS, overall survival; PEI, percutaneous ethanol injection; RF, radiofrequency ablation; TACE, transcatheter arterial chemoembolization. (Modified with permission from JM Llovet et al: Molecular pathogenesis and systemic therapies for hepatocellular carcinoma. Nature Cancer 3:386, 2022.) *Around 70–80% of patients are expected to receive this regimen #Based on high level evidence studies. ##Based on low or moderate level of evidence studies. measures—total bilirubin, serum albumin, prothrombin time, ascites severity, and hepatic encephalopathy grade—to classify patients into one of three groups (A–C) of predicted survival rates. In brief, ChildPugh class A reflects well-preserved liver function, Child-Pugh class B moderate liver dysfunction, and Child-Pugh class C severe liver dys­ function. Other measurements of liver dysfunction, such as the Model for End-Stage Liver Disease (MELD) score or the albumin-bilirubin score, are not integrated in this staging system. Performance status is assessed by Eastern Cooperative Oncology Group (ECOG) scale (a 5-point scale where higher numbers indicate greater disability), and presence of cancer-related symptoms (ECOG 1–2) is considered a sign of advanced stage. Considering all these prognostic/predictive variables and evidencebased treatment efficacy, five BCLC stages have been defined (Fig. 87-3). Patients with liver-only neoplastic disease, no symptoms (ECOG 0), and mild to moderate liver dysfunction (Child-Pugh A-B) can be clas­ sified as very early (stage 0), early (stage A), or intermediate (stage B) stage depending on tumor size and number. Very early HCC (BCLC 0) is defined by single tumors ≤2 cm (if pathology is available, the tumors should be well-differentiated with absence of microvascular invasion or satellites). Early HCC (BCLC A) includes either single tumors or a Intermediate (BCLC B) Advanced (BCLC C) Terminal (BCLC D) - Portal invasion, N1, M1 - Child Pugh A-B, ECOG 1–2 - Multinodular - Child-Pugh A-B, ECOG 0 - Child Pugh C - ECOG >2 TACE candidate No Yes CHAPTER 87 Chemoembolization (+ systemic therapies) Tumors of the Liver and Biliary Tree Median OS ~26–30 mo mPFS: 15 mo 1st line: ~16–19 mo 2nd line: 13–15 mo 3rd line: 8–12 mo Median OS 3–6 months maximum of three nodules of ≤3 cm in diameter. Intermediate stage (BCLC B) is defined by all other liver-only tumors. Conversely, HCC is considered at advanced stages (BCLC C) when patients present with cancer-related symptoms (ECOG 1–2) or tumors with macrovascular invasion (of any type, including branch, hepatic, or portal vein), lymph node involvement, or extrahepatic spread. Finally, end-stage disease (BCLC D) is considered in cases of severe impairment of quality of life or severe cancer-related symptoms (ECOG 3–4) or severe liver dysfunction (Child-Pugh C). Around 40% of patients are diagnosed at stages 0 and A and hence are eligible for potentially curative therapies, resection, transplantation, or local ablation. These treatments provide median survival rates of 60 months and beyond, which are in sharp contrast with outcomes of 36 months reported in historical controls (Fig. 87-3, Table 87-2). Adjuvant therapy with atezolizumab plus bevacizumab is recom­ mended in patients after resection or local ablation who are at high risk of recurrence. Patients at intermediate stage (stage B) with preserved liver function have a documented natural history of around 16 months. These patients benefit from TACE, as reported in two randomized studies and one meta-analysis and achieve an estimated survival of 25–30 months. Combination of durvalumab plus bevacizumab with TACE TABLE 87-2  Summary of Key Results of Randomized and Cohort Studies in the Management of Hepatocellular Carcinoma (HCC) TREATMENT OF EARLY AND INTERMEDIATE STAGE HCC TREATMENTS HCC STAGE TREATMENT ARMS OUTCOMES (OS) Treatments for early HCC Resection Early Optimal (single nodule; no portal hypertension) 5-year: 50–70% Suboptimal (multinodular or portal hypertension) 5-year: 35–55% Resection + adjuvant Early Adjuvant atezolizumab + bevacizumab vs surveillance 12-month RFS: 78 vs 65% Liver transplantation Early Milan (1 nodule <5 cm, 2–3 nodules ≤3 cm, no MVI, no EHS) 5-year: 70–80% Early/intermediate Downstaged (1 nodule ≤6.5 cm, ≤3 nodules ≤4.5 cm and total diameter ≤8 cm, no MVI, no EHS) Ablation Early RFA Median: 50–60 months Treatments for intermediate HCC Transarterial therapies Intermediate TACE Median: 20–32 months Median PFS: 8 months Locoregional + systemic Intermediate TACE + durvalumab + bevacizumab Median PFS: 15.2 months TREATMENT OF ADVANCED STAGE HCC STUDY NAME TREATMENT MEDIAN OS, MONTHS (HR 95% CI) MEDIAN PFS, MONTHS (HR 95% CI) ORR mRECIST/RECIST First-line therapies IMbrave150 Atezolizumab + bevacizumab 19.2 vs 13.5 (HR 0.66, 0.452–0.85) 6.9 (HR 0.65, 0.53–0.81) 35.4%/29.8% HIMALAYA Durvalumab + tremelimumab 16.4 (HR 0.78, 0.65–0.93) 3.7 (HR 0.90, 0.77–1.05) NA/20% PART 4 Oncology and Hematology SHARP Sorafenib 10.7 (HR 0.69, 0.55–0.87) 10.7 (HR 0.69, 0.55–0.87) NA/2% REFLECT Lenvatinib 13.6 (HR 0.92, 0.79–1.06) 7.4 (HR 0.66, 0.57–0.77) 24.1%/18.8% Second-line therapies RESORCE Regorafenib 10.6 (HR 0.63, 0.5–0.79) 3.1 (HR 0.46, 0.37–0.56) 11%/7% CELESTIAL Cabozantinib 10.2 (HR 0.76, 0.63–0.92) 5.2 (HR 0.44, 0.36–0.52) NA/4% REACH-2 Ramucirumab 8.5 (HR 0.71, 0.53–0.95) 2.8 (HR 0.45, 0.34–0.6) NA/5% Abbreviations: CI, confidence interval; EHS, extrahepatic spread; HCC, hepatocellular carcinoma; HR, hazard ratio; mRECIST, modified Response Evaluation Criteria in Solid Tumors; MVI, microvascular invasion; NA, not available; ORR, overall response rate; OS, overall survival; PFS, progression-free survival; RFA, radiofrequency ablation; TACE, transarterial chemoembolization. has shown benefits in progression-free survival compared with TACE alone. Patients progressing on TACE or at advanced stage (stage C) benefit from systemic treatments. First-line therapy for advanced HCC includes atezolizumab plus bevacizumab or durvalumab plus tremelimumab. Both combinations were superior to sorafenib in phase 3 trials. In patients with contraindications for immunotherapies, both sorafenib or lenvatinib are recommended Three additional targeted therapies have shown to improve survival compared to placebo in patients with HCC progressing on sorafenib: regorafenib, cabozantinib, and ramucirumab (only in patients with AFP >400 ng/mL). Therefore, these treatments have been adopted by guidelines and incorporated into the treatment algorithm. Patients with end-stage disease (BCLC D) should be considered for nutritional and psychological support and proper management of pain. Although the BCLC establishes validated stages and treatment assignment according to evidence, clinical practice is not always aligned with this classification. In large cohort studies and surveys, only half of patients, or even less in Asia, are treated accordingly. Alterna­ tive staging or scoring systems have been proposed, such as the Hong Kong classification or the Japan Integrated Staging score. These systems capture extended indications for resection and TACE applied in clini­ cal practice in Asia. Finally, the tumor-node-metastasis (TNM) stag­ ing system is not used in HCC since it does not incorporate the main prognostic variables related to liver function and performance status. Due to the complexities of HCC diagnosis and management, it is recommended to refer patients to centers with multidisciplinary liver cancer programs that include a hepatologist, oncologist, hepatobiliary and transplant surgeons, interventional and body imaging radiologist, hepatopathologist, and specialized nurses. ■ ■SURGICAL THERAPIES Resection  Surgical resection is the first-line option for noncirrhotic patients with early-stage HCC (BCLC 0 or A) with solitary tumors 5-year: 60–70% (Fig. 87-3). In cirrhotic patients, ablation competes with resection for BCLC 0 tumors (<2 cm in diameter). Which is better is not defined. Cost-effectiveness approaches report a benefit for local ablation with RF. For single tumors >2 cm (BCLC A), resection remains the mainstay of treatment in patients with Child-Pugh A with normal bilirubin and absence of portal hypertension (no esophageal/gastric varices or platelet count >100,000/µL associated with splenomegaly). Anatomic resections following the functional segments of the liver are recommended to spare uninvolved liver parenchyma and to remove satellite tumors. Applying these criteria, resection is associated with perioperative decompensa­ tion rate of 5%, perioperative mortality of <1%, and 5-year survival of 60–70%, as opposed to ~35–55% for suboptimal candidates (Table 87-2). Macrovascular invasion, extrahepatic involvement, and liver dys­ function (Child-Pugh B-C) are major contraindications for resection. Adjuvant Treatments  Tumor recurrence represents a major com­ plication of resection and local ablation (with 5-year rates of 50–70%). Predictors of recurrence are tumor size, tumor number, presence of microsatellites, or microvascular invasion at the specimen analysis. Most recurrences are intrahepatic metastases, but at least one-third are considered de novo tumors, new clones developing in the cirrhotic car­ cinogenic field. The type of recurrence can only be defined by molecu­ lar studies. An adjuvant regimen after resection or local ablation with atezolizumab plus bevacizumab for 12 months significantly improved recurrence-free survival in patients at high risk of recurrence and has been incorporated into the guidelines of practice. Liver Transplantation  Liver transplantation is the first treatment choice for cirrhotic patients with single tumors ≤5 cm and portal hyper­ tension (including Child-Pugh B and C) or with small multinodular tumors (three or fewer nodules, each ≤3 cm) (Fig. 87-3). These so-called Milan criteria have been validated over the years and lead to median sur­ vival times of 10 years. Perioperative mortality rates have been reduced to <3%. Transplantation simultaneously cures the tumor and the underlying cirrhosis, and it is associated with a low risk of recurrence, around 10–15% at 5 years. No immunosuppressive regimens or antitu­ mor therapies after transplantation have demonstrated any preventive effect on recurrence. Milan criteria are integrated in the treatment strat­ egy (BCLC 0 and A) and have also been adopted by the United Network for Organ Sharing (UNOS) pretransplant staging for organ allocation in the United States (stage T2). Aside from size and number, conventional contraindications for organ transplantation procedures (e.g., ABO incompatibility, comorbidities) are applied in this setting. Liver transplantation has a couple of important limitations, such as cost and donor availability, that limit this procedure to <5% of HCC cases worldwide. The scarcity of donors represents a major drawback of liver transplantation. Donor scarcity varies geographically, and deceased liver donation is almost zero in some Asian countries. Due to the shortage of donors, median waiting times in Western programs is ~6–12 months, leading to 20% of candidates dropping off the list due to tumor progression before receiving the procedure. Neoadjuvant treat­ ments with locoregional therapies are recommended when the waiting time exceeds 6 months. Expansion of Milan criteria by using locoregional therapies to effec­ tively downstage the tumor (i.e., UNOS-downstaging criteria) have reported good results. Since policies for enhancing organ donation have reached a ceiling during the past several years, alternatives to donation have emerged. Living donor liver transplantation represents a plausible alternative that accounts for ~5% of total transplantations performed globally. Outcomes reported are similar to those with deceased liver donors, and it is recommended as an alternative option in patients on a waiting list exceeding 6 months. The risks and ben­ efits of this procedure should take into account both donor (death is estimated in 0.3%) and recipient, a concept known as double equipoise. Due to the complexity of this treatment, it must be restricted to centers of excellence in hepatobiliary surgery and transplantation. ■ ■LOCOREGIONAL THERAPIES Local Ablation  Thermal ablation with RF or microwave (MWA) is recommended as the primary ablative technique (Fig. 87-4). The Advanced stage HCC (BCLC C, portal invasion and/or extrahepatic spread) or Intermediate stage HCC (BCLC B, multinodular) progressing upon/not candidates for loco-regional therapies. Child-Pugh A, ECOG 0–1 Candidate for immunotherapy? Yes No (Autoimmune disorder, Prior liver transplantation) High risk of gastrointestinal/ esophageal bleeding Yes No First/second line Atezolizumab + bevacizumab* Tremelimumab + durvalumab Sorafenib or Lenvatinib PD Second/third line Regorafenib/cabozantinib/ramucirumab Nivolumab + ipilimumab Pembrolizumab FIGURE 87-4  Treatment strategy for advanced hepatocellular carcinoma with systemic therapies. Drugs in bold have positive results from phase 3 trials with regulatory approval (atezolizumab plus bevacizumab, durvalumab plus tremelimumab, sorafenib, lenvatinib, regorafenib, cabozantinib, and ramucirumab). Drugs in bold italic have received accelerated approval from the Food and Drug Administration on the basis of promising efficacy results in phase 2 trials in second line (pembrolizumab and nivolumab ipilimumab). Key details of the patient populations are provided. BCLC, Barcelona Clinic Liver Cancer (classification); ECOG, Eastern Cooperative Oncology Group; PD, progressive disease. (Modified from JM Llovet et al: Nat Rev Clin Oncol 15:599, 2018.) energy generated by RF ablation (heating of tissue at 80°–100°C) induces coagulative necrosis of the tumor, producing a safety ring in the peritumoral tissue, which might eliminate small undetected satellites. Treatment consists of one or two sessions performed using a percutaneous approach, although in some instances, ablation with laparoscopy is needed. HCC patients treated by RF ablation have 5-year survival rates of ~60% (Table 87-2). In tumors <2 cm, both RF and MWA ablation achieve complete responses in 90–100% of cases with good long-term outcome and compete with resection in terms of cost-effectiveness as a first-line option. For BCLC A cases, local abla­ tion techniques are considered in patients with three tumors <3 cm in diameter unsuitable for surgical therapies. For patients with unresectable HCC >3 cm in diameter who are not candidates for liver transplantation, transarterial radioemboliza­ tion (TARE) with yttrium-90 and stereotactic body radiation (SBRT) are considered alternative options based on propensity-matched score studies and phase 2 investigations. Chemoembolization  TACE is the most widely used primary treatment for unresectable HCC worldwide and the first-line indica­ tion for patients with intermediate BCLC B stage (Fig. 87-3). Conven­ tional chemoembolization (c-TACE) consists of local hepatic artery administration of chemotherapy (either doxorubicin 50 mg/m2 or cisplatin) mixed with an emulsion of lipiodol followed by obstruction of the feeding artery with sponge particles. The best randomized phase 3 investigations have provided median survivals for TACE of 20–30 months in properly selected populations (compared to 16 months for pooled control arms). Median objective response rates are 50–70%. In randomized studies, the treatment is either performed at a regular schedule of 0, 2, and 6 months (median number of sessions is three) or on demand according to tumor response. TACE procedures should be stopped upon tumor progression or any other contraindication. Around 50% of patients present with a limited postembolization syndrome of fever and abdominal pain related to ischemic injury and release of cytokines. Less than 5% of patients have major com­ plications (liver abscess, ischemic cholecystitis, or liver failure), and CHAPTER 87 Tumors of the Liver and Biliary Tree in <2% of cases, treatment-related death occurs. Drug-eluting bead chemoembolization (DEB-TACE) differs from c-TACE in the use of more standardized embolic spheres of regular size embedded with chemotherapy. This strategy achieves similar antitumor activity (objec­ tive responses of ~60%) as c-TACE and is associated with significantly fewer systemic toxic effects and better patient tolerance, but there are no clear differences in clinical outcomes. Overall, TACE can only be applied to 50% of patients at intermediate stage, mostly as a result of the presence of liver failure (Child B or asci­ tes or encephalopathy), technical contraindications to the procedure (i.e., impaired portal vein blood flow), or infiltrative/massive tumor burden (i.e., generally main tumor size >10 cm). Super-selective TACE minimizes the ischemic insult to nontumor tissue. According to guide­ lines, treatment stage migration allows performing TACE on patients at early stages not suitable for surgical or ablative therapies. TACE plus durvalumab plus bevacizumab significantly increases progression-free survival compared to TACE alone (median progression-free survival, 15.2 vs 8 months) with manageable treatment-related adverse events. Radioembolization and Other Intra-arterial Therapies  Trans­ arterial radioembolization (TARE) using beads coated with yttrium-90 (Y-90)—an isotope that emits short-range β radiation—is the most promising alternative to TACE. Several phase II studies reported objective responses and overall outcome with a safe profile similar to TACE, and thus TARE has been endorsed by clinical practice guide­ lines. Radioembolization requires prevention of severe lung shunting and intestinal radiation before the procedure. Around 20% of patients experience liver-related toxicity, and <2% experience treatment-related death. Due to the minimally embolic effect of Y-90 microspheres, treatment can be safely used in patients with portal vein thrombosis, a setting where survival results in phase II studies were encouraging. PART 4 Oncology and Hematology ■ ■SYSTEMIC THERAPIES Approximately 50–60% of patients with HCC are currently exposed to systemic therapies during their life span, either because they have been diagnosed at advanced stages or because they have progressed after locoregional therapies. In 2007, a phase III trial demonstrated survival benefits for patients with advanced-stage disease treated with sorafenib, thus becoming the first systemic therapy for HCC. Subsequently atezolizumab plus bevacizumab and durvalumab plus tremelimumab have demonstrated survival superiority compared to sorafenib, whereas lenvatinib showed noninferior effects (Fig. 87-4). In Asia, other combinations (i.e., carmelizumab plus rivoceranib) also were superior versus sorafenib in terms of survival. Three addi­ tional therapies, regorafenib, cabozantinib, and ramucirumab (only in patients with AFP >400 ng/mL), have been shown to benefit patients progressing on sorafenib. Of note, classical chemotherapy and radio­ therapy have not resulted in benefits in survival. Similarly, due to the low prevalence of actionable molecular aberrations, precision oncology regimens are not yet available in HCC. First-Line Therapies  Atezolizumab (anti–PD-1 checkpoint inhibitor) plus bevacizumab (monoclonal antibody against VEGF-A) demonstrated survival differences compared to sorafenib (median OS, 19.2 vs 13.4 months) and has become the standard of care in first-line treatment (Fig. 87-4, Table 87-2). This combination treatment resulted in improved progression-free survival, patient-reported outcomes reflecting quality of life, and objective response rates (30 vs 12% for sorafenib). The combination had fewer adverse events compared to sorafenib (grade 3-4 adverse events, 36 vs 50%, respectively). The most common side effects associated with the combination are hyperten­ sion, proteinuria, and low-grade diarrhea, whereas autoimmune events are infrequent and manageable. Treatment-related adverse event rate leading to discontinuation of any drugs is 15%. Screening for varices with upper gastrointestinal endoscopies has become standard before first-line therapy in advanced HCC to mitigate the risk of bleeding associated with bevacizumab. In cases with varices, the use of one ses­ sion of banding or carvedilol is recommended. The combination of tremelimumab (a CTLA-4 inhibitor) and dur­ valumab (a PD-L1 inhibitor) (STRIDE regimen) has demonstrated a survival advantage versus sorafenib (median OS, 16.4 vs 13.7 months for sorafenib). No differences were identified regarding progressionfree survival, and the response rate was 20.1% with the combination versus 5.1% with sorafenib. This regimen can be administered even in patients with portal hypertension or varices. STRIDE was associ­ ated with more immune-related adverse events, and 20% of patients required glucocorticoid treatments (Fig. 87-4). Alternatively, sorafenib or lenvatinib is indicated for patients with advanced HCC with contraindications for immunotherapies (i.e., due to autoimmune disease or liver transplantation) (Fig. 87-4, Table 87-2). A phase 3 study comparing sorafenib (a multikinase inhibitor) versus placebo showed increased survival from 7.9 months to 10.7 months (hazard ratio [HR], 0.69; 31% reduction in risk of death). Patients with HCV-related HCC achieve significantly better outcomes with sorafenib, with a median survival of 14 months. Median treatment duration is about 6 months. Treatment is associated with manageable adverse events, such as diarrhea, hand-foot skin reactions, fatigue, and hypertension. These toxicities lead to treatment discontinuation in 15% of patients and dose reduction in up to half. It has been estimated that this therapy cannot be administered to approximately one-third of the targeted patients due to toxicity, advanced age, or liver failure (ascites or encephalopathy). Active vascular disease, either coronary or peripheral, is considered a formal contraindication. Median time to progression on sorafenib is 4–5 months in phase 3 trials. Another alternative to sorafenib is the multikinase inhibitor len­ vatinib, which was shown to be noninferior in a phase 3 investiga­ tion (Fig. 87-4). A phase 3 study comparing lenvatinib (an inhibitor of vascular endothelial growth factor receptor [VEGFR], fibroblast growth factor recepctor [FGFR], platelet-derived growth factor recep­ tor [PDGFR], RET, and c-Kit) with sorafenib showed noninferiority of results in terms of OS (13.6 vs 12.3 months; HR, 0.92). Lenvatinib induces objective responses in 24% of cases. The main side effects are hypertension, proteinuria, asthenia, diarrhea, and weight loss. This treatment is associated with a 55% rate of grade 3-4 drug-related adverse events, resulting in a ~15% withdrawal rate. Second-Line Therapies  Three drugs (regorafenib, cabozantinib, and ramucirumab) have shown survival benefits versus placebo in patients progressing to sorafenib, and two additional treatments have been approved by the U.S. Food and Drug Administration (FDA) based on promising phase 2 data (pembrolizumab, and nivolumab plus ipilimumab) (Fig. 87-4). It is estimated that only half of patients progressing on sorafenib can be considered for second-line therapies, and their median survival with no treatment is 7–8 months (obtained from patients allocated to the placebo arm). A phase 3 study comparing regorafenib (a more potent multikinase inhibitor than sorafenib, but targeting similar kinases) versus placebo in patients progressing to sorafenib reported an increase in survival from 7.8 to 10.6 months (HR, 0.62; 38% reduction in risk of death) (Fig. 87-5). Response rate was 10% based on modified Response Evaluation Criteria in Solid Tumors. Median time on treatment was 3.5 months. Prevalence of toxicity (hand-foot reaction, fatigue, and hypertension) was higher compared with reported toxicity from sorafenib, but adverse events only led to treatment discontinuation in 10% of cases. Cabozantinib, a multikinase VEGFR inhibitor with activity against both AXL and cMET, improves survival compared to placebo after progression to sorafenib (10.2 months for cabozantinib vs 8.0 months in the placebo arm; HR, 0.76). Toxicity was manageable, with the most common grade 3–4 events being palmar-plantar erythro­ dysesthesia, hypertension, increased aspartate aminotransferase level, fatigue, and diarrhea. Ramucirumab, an anti–VEGFR-2 monoclonal antibody, is the only biomarker-guided therapy in HCC based on AFP levels. The randomized, placebo-controlled, phase 3 REACH-2 study studied patients with advanced HCC in second-line treatment with baseline AFP ≥400 ng/dL. This trial demonstrated positive survival results, and a further meta-analysis established a median survival for ramucirumab of 8.1 months compared to 5 months for patients receiv­ ing placebo. The most common grade 3–4 treatment-related adverse events were hypertension, hyponatremia, and increased aspartate Mass-forming Periductalinfiltrating Left, right, common hepatic ducts Intraductalgrowing FIGURE 87-5  Anatomical classification of cholangiocarcinoma. Cholangiocarcinoma is classified as intrahepatic (iCCA) and extrahepatic (eCCA). eCCA can be subclassified as perihilar (pCCA) and distal (dCCA). (Reproduced from JM Banales et al: Cholangiocarcinoma 2020: The next horizon in mechanisms and management. Nat Rev Gastroenterol Hepatol 17:557, 2020.) aminotransferase. Patients progressing after second-line therapy might be considered for third-line approaches. Patients with tumors at a BCLC D stage should receive best supportive palliative care, including management of pain, nutrition, and psychological support. CHOLANGIOCARCINOMA Cholangiocarcinoma (CCA) is classified according to its anatomic location as intrahepatic (iCCA; ~20–30%), perihilar (pCCA; ~50–60%), and distal (dCCA: ~20–30%). The latter two are also known as extra­ hepatic cholangiocarcinomas (eCCA), with the second-order bile ducts acting as the separation point (Fig. 87-5). The three subtypes of CCA differ in their anatomic location, epidemiology and risk factors, cell of origin, pathogenesis, and treatment. iCCA originates from adult cholangiocytes, transdifferentiation of adult hepatocytes, and hepatic progenitor cell–cholangiocyte precursors (Fig. 87-6), as opposed to HCC, which originates only from hepatic progenitor cells or adult hepatocytes. Mixed HCC-iCCA originates from hepatic progenitor cells, whereas eCCA arises from the biliary epithelium and peribiliary glands. Moreover, their mutational profile also differs. FGFR2 fusions and IDH1/2 mutations mostly occur in iCCA, whereas ERBB2/3 ampli­ fications and SMAD4 aberrations are characteristic of eCCA. iCCA has been recognized as a distinct entity with specific clinical practice guidelines, which should be tailored according to each biological/ anatomical subtype of CCA. ■ ■EPIDEMIOLOGY, RISK FACTORS, AND MOLECULAR TRAITS CCA is the second most common liver cancer following HCC, with a 5-year survival of 10%. iCCA has globally increasing incidence and mortality rates. The incidence of iCCA varies according to exposure to risk factors, ranging from 1–2 cases per 100,000 inhabitants in Europe and North America to the highest incidence in some areas of Southeast Asia, particularly in Thailand (>80 cases/100,000 inhabitants). The male-to-female ratio is 1.2:1. Only 30% of patients with CCA have a known risk factor. The classical risk factors for CCA development include primary sclerosing cholangitis (PSC), biliary duct cysts, hepa­ tolithiasis, and Caroli’s disease. Parasitic biliary infestation with flukes (most common are Opisthorchis viverrini and Clonorchis sinensis) is a prevalent etiology in Asia that can be prevented with an antihel­ minth therapy, praziquantel. PSC is a clear risk factor for iCCA and pCCA development, with a lifetime incidence ranging from 5 to 10%. Surveillance in PSC patients is recommended with annual imaging techniques and CA 19-9 serum determina­ tion. Common risk factors for HCC, such as HBV and HCV infection and cirrhosis, have been associated with iCCA develop­ ment. More recently, sweetened beverages were reported to constitute a risk factor in the development of eCCA and gallbladder carcinoma (GBC) in a population cohort study. Bile ductules iCCA (10–20%) Segmental ducts Molecular Classification and Actionable Drivers  A morphological and molecular classification subclassifies iCCA into the large duct type, which is associated with IDH (15–20%) and FGFR2 (15%) mutations and better prognosis, and the small duct type, which is associated with KRAS (15%) and SMARD4 (<5%) mutations and poor prognosis. Overall, up to 40% of iCCAs have a targetable mutation. Similarly, a molecular classification of eCCA has been proposed, dividing tumors into four cat­ egories (metabolic, proliferation, mesen­ chymal, and immune) based on molecular traits. It has been suggested that the prolif­ eration class with enrichment of ERBB2/3 mutations might respond to monoclonal antibodies against this receptor, while the immune class might respond to checkpoint inhibitors, a fact that needs clinical confirmation. The most common mutations of pCCA/dCCA are P53 (~30%) and KRAS (~25%), whereas ERBB2 amplifications (~20%) are common in gall­ bladder cancer. pCCA (50–60%) Common bile duct dCCA (20–30%) CHAPTER 87 Tumors of the Liver and Biliary Tree ■ ■INTRAHEPATIC CHOLANGIOCARCINOMA Surveillance, Diagnosis, and Staging  Guidelines currently only recommend surveillance for early diagnosis in the following atrisk subpopulations: (1) patients with primary biliary sclerosis (PBS; surveillance is recommended with CA 19-9 and magnetic resonance cholangiopancreatography [MRCP] every 12 months) and (2) patients with cirrhosis or those infected with liver flukes (surveillance is rec­ ommended with abdominal ultrasound every 6 months). Otherwise, incidental diagnosis occurs due to cross-sectional imaging performed for other reasons. In most cases, iCCA is diagnosed at advanced stages when symptoms such as weight loss, malaise, abdominal discomfort, or jaundice are present. Diagnosis of iCCA requires pathological con­ firmation. Differential diagnosis should be established with metastatic adenocarcinoma (i.e., colorectal, breast, and lung cancer) and mixed iCCA-HCC tumors. Immunohistochemistry using K7, K19, and K20 is useful to confirm iCCA and to distinguish it from metastatic liver cancer. Hepatocytic markers such as Hep-Par-1, GPC3, and HSP70 may aid in pointing to a mixed HCC-iCCA tumor. Current guidelines recommend the use of abdominal MRI, chest and abdomen CT scan, and PET scan for establishing the disease extension once the pathologi­ cal diagnosis has been confirmed. Meta-analysis has defined a role for PET scanning in identifying lymph node metastasis in patients with no apparent lymph node invasion with MRI and/or CT scan. Lymph node sampling by endoscopic ultrasound with fine-needle aspiration would be considered before resection in selected unclear cases. Tumor biomarker CA 19-9 at a cutoff level of 100 U/mL has prognostic sig­ nificance but lacks accuracy (sensitivity and specificity of ~60%) for early diagnosis. ■ ■TREATMENT The European Association for the Study of Liver Disease–International Liver Cancer Association (ILCA) guidelines for management of iCCA proposed an updated treatment algorithm, which has been adapted to the current accepted treatment modalities (Fig. 87-7). iCCA can be classified as early, intermediate, or advanced cases according to size of the nodules and invasion of lymph nodes (N1), metastasis, and ECOG Hepatic progenitor cell Progenitor-like HCC Progenitor-like iCCA Hepatocyte precursor Cholangiocyte precursor De-differentiation Mixed HCC-iCCA Biliary-like cell Mature hepatocyte Transdifferentiation PART 4 Oncology and Hematology HCC iCCA FIGURE 87-6  Cell of origin of liver cancer. Hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (iCCA) can develop from the neoplastic transformation of mature hepatocytes and cholangiocytes, respectively. There is evidence showing that hepatic progenitor cells (HPCs), their intermediate states, or dedifferentiated hepatocytes can originate liver cancers with progenitor-like features, including mixed HCC-CCA (e.g., cholangiolocellular carcinoma [CLC]). Mature hepatocytes can be also reprogrammed into cells that closely resemble biliary epithelial cells and induce the onset of iCCA. (Printed with permission from © Mount Sinai Health System.) performance status and liver dysfunction. Approximately 30–40% of iCCA cases are deemed resectable, and the median reported survival for single tumors is ~40–50 months, whereas survival decreases to ~20 months in intermediate/multinodular resectable tumors. The main predictors of recurrence (~50–60% at 3 years) and survival are identified at the pathological examination, including presence of vascular invasion, lymph node metastases, and poor differentiation degree. In terms of adjuvant therapy, a phase 3 trial (BILCAP trial) including all types of CCA in a prespecified per-protocol analysis reported improved survival (53 vs 36 months; adjusted HR, 0.75). Based on this trial, American Society of Clinical Oncology guidelines recommend adjuvant capecitabine for a period of 6 months. A small proportion of patients with early/intermediate tumors can have contra­ indications for resection, particularly in cirrhotic patients, and should be first considered for local ablation or even liver transplantation if the diameter of the main tumor is <2 cm. Nonsurgical candidates have a dismal life expectancy. Overall, patients with multinodular unresectable tumors might be considered for locoregional therapies, such as chemoembolization or radioembo­ lization, but the level of evidence is low and mostly based on cohort studies. A meta-analysis of 14 trials testing locoregional therapies reported median survival times of 15 months. External-beam radiation therapy is not recommended as standard therapy. At more advanced stages in patients with ECOG of 0–1, systemic chemotherapy with the combination of gemcitabine, cisplatin, and durvalumab showed significantly better survival and progression-free survival compared with gemcitabine plus cisplatin alone (12.8 vs 11.5 months) in the setting of the TOPAZ1 phase 3 trial including 685 patients. Objective response was 27%. Similar results were obtained with the combination De-differentiation? CLC Mature cholangiocyte Tumor type HCC iCCA Mixed HCC-iCCA of chemotherapy with pembrolizumab versus chemotherapy alone in a phase 3 trial including 1069 patients. The median OS was 12.7 months in the pembrolizumab group and 10.9 months in the placebo group (HR, 0.83; 95% CI, 0.72–0.95; one-sided p = .0034). Therefore, triplet therapy is now considered the standard for the management of CCA. In the second-line setting, a phase 3 study that randomized patients who had progressed on cisplatin and gemcitabine to mFOLFOX (leucovorin, fluorouracil, and oxaliplatin) versus best supportive care showed improvement in median OS of 5.3 to 6.2 months (adjusted HR, 0.69). In addition, three molecular and immune therapies have been approved in the second-line setting in iCCA patients with IDH1/2 mutations, FGFR2 aberrations, or deficient mismatch repair (dMMR) or microsatellite instability high (MSI-H). A phase 3 trial compared ivosidenib, an IDH-1 inhibitor, versus placebo in the second-line set­ ting and demonstrated an improved primary end point of progressionfree survival (2.7 vs 1.4 months; HR, 0.37) and improved OS in an adjusted analysis. A single-arm phase 2 study assessing pemigatinib (FGFR2 inhibitor) in iCCA patients with FGFR2 fusions showed a median survival of 21 months with an objective response of 35%, lead­ ing to FDA accelerated approval. Similar results have been observed in phase 3 trials testing other FGFR2 inhibitors, such as infigratinib and futibatinib. Finally, regulatory agencies granted approval of pembroli­ zumab for MSI-H or dMMR solid tumors that progressed following prior treatment based on a basket tissue-agnostic trial. This recom­ mendation excludes patients receiving durvalumab in first line. Mixed HCC-iCCA is a rare neoplasm accounting for <0.5% of all primary liver cancers. Diagnosis is based on pathology. The 2010 World Health Organization classification defined two subtypes: the classical type and the stem cell feature type. Molecular data have also Intrahepatic cholangiocarcinoma (iCCA) Advanced, metastatic disease (Periductal invasion, N1, M1) Early and intermediate stages Resectable (30–40%) Intrahepatic Disease only Single iCCA ≤2 cm in cirrhotic patient Extrahepatic Disease Local-ablation (or Liver Transplantation) Surgical resection (curative intent) Adjuvant chemotherapy (capecitabine/6 mo) Median survival: 43 mo Median survival: 15 mo *Treatments used as standard of practice. No enough evidence for standard of care. **Patients with ECOG > 2 or liver dysfunction are only suitable for best supportive care. FIGURE 87-7  Staging and treatment schedule for intrahepatic cholangiocarcinoma (iCCA). (Modified from EASL-ILCA Guidelines. J Hepatol 79:181, 2023.) characterized a third unique entity, cholangiolocellular carcinoma, with distinct molecular traits and better outcome. Due to their low incidence, the demographic features and clinical behavior of these tumors remain ill-defined. Survival and management are similar to iCCA. ■ ■EXTRAHEPATIC CHOLANGIOCARCINOMA Perihilar and Distal Cholangiocarcinoma  pCCA tumors arise between the second-order bile ducts up to the insertion of the cystic duct, whereas dCCAs arise from this point to the ampulla of Vater (Fig. 87-5). Thus, dCCA can be difficult to distinguish from early pan­ creatic cancer. Both entities have a similar diagnostic approach. Acute onset of painless jaundice occurs in 90% of patients with pCCA, and 10% of patients present with cholangitis. Primary biliary cholangitis with a cutoff for CA 19-9 >129 U/mL is suspicious for CCA. Imag­ ing assessment starts with CT and MRI; they have a good sensitivity and specificity (>85%) for detecting the degree of bile duct involve­ ment and hepatic and portal vein invasion. MRI cholangiography is optimal for defining the extent of the bile duct lesion. Ruling out IgG4 cholangiopathy by assessing serum IgG4 is mandatory. As a second step, endoscopic retrograde cholangiography with brushing to explore cytology and fluorescence in situ hybridization (FISH)—for exploring polysomy—are recommended. FISH enhances the sensitivity of cytol­ ogy from 20 to ~40%. Diagnosis is based on pathology. The treatment algorithm for pCCA indicates that in cases of a dominant stricture with positive cytology/biopsy or polysomy, a lymph node biopsy through endo­ scopic ultrasound should be obtained. pCCA with negative lymph node involvement is best treated by surgery, resection, or transplantation, Unresectable (60–70%) Local-regional therapy* Chemoemboliation (TACE) Radioembolization (TARE) 1st line**: Gemcitabine+ cisplatin+ (durvalumab or pembrolizumab) CHAPTER 87 2nd line FOLFOX FGFR2 inhibitor (pemigatinib) IDH inhibitor (ivosidenib) Checkpoint inhibitor for MSI-H/dMMR Tumors of the Liver and Biliary Tree Median survival: 1st line : ~13 mo 2nd line : 6–12 mo the sole curative options. Staging laparoscopy is recommended to exclude metastatic disease prior to surgery, which occurs in 15% of cases. Resection entails hepatic and bile duct removal and Roux-enY hepaticojejunostomy with regional lymphadenectomy. Bilobular involvement is considered a surgical contraindication. Perioperative mortality rate is up to 10%, mostly as a result of liver failure. In a few referral centers, unresectable single pCCAs <3 cm without dissemi­ nation can be considered for liver transplantation with neoadjuvant chemoradiation. This procedure is associated with 5-year survival rates of ~70%. If lymph node involvement is present, systemic chemotherapy can be considered along with biliary tract stenting. Surgical resection (Whipple procedure) is the primary option for management of dCCA, a procedure that achieves a median survival of 24 months and 5-year survival rates of ~25%. Main contraindications for resection are pres­ ence of distant lymph node involvement, metastases, or major vascular invasion. At the pathological examination, perineural invasion, lymph node metastasis, R0 resection (absence of residual tumor at pathologi­ cal examination), and tumor differentiation are predictors of survival. Adjuvant therapy with capecitabine for 6 months is accepted based on the BILCAP study, which has been previously discussed. For advanced cases, consensus statements endorse first-line (gemcitabine and cis­ platin plus durvalumab or pembrolizumab) and second-line therapies (FOLFOX) similar to those for iCCA. No molecular targeted therapies are available for these entities. ■ ■GALLBLADDER CANCER Gallbladder cancer is the most common cancer of the biliary tract worldwide. The estimated number of cases of gallbladder cancer in the United States in 2016 was 11,400, more than CCA. The female-to-male ratio is 3:1. Cholelithiasis is the major risk factor, but <1% of patients with cholelithiasis develop this cancer. Gallbladder polyps at risk of transformation are those ≥10 mm in diameter. Early cases are discov­ ered incidentally at routine cholecystectomy. Clinical symptoms, such as jaundice, pain, and weight loss, are associated with advanced stages. Staging of gallbladder cancer involves local disease (tumor confined to the gallbladder) and advanced disease (tumor outside gallbladder with lymph node or distant metastases). The most accurate technique to define staging and vascular and biliary tract invasion is the magnetic resonance cholangiopancreatography. CT and PET scan can also be useful for preoperative staging. The mainstay of treatment is surgical resection, either simple or radical cholecystectomy (partial hepatectomy and regional lymph node dissection) for local disease. Only ~20% of patients are candidates for surgery with curative intent, and 5-year survival rates range from 60 to 90% depending on prognostic factors such as lymph node or tumor invasion beyond muscular layer. Adjuvant therapy with capecitabine is recommended in R0 cases. Gallbladder cancers at advanced stage are considered unresectable. For patients with ECOG of 0–1, chemother­ apy with gemcitabine, cisplatin, and durvalumab is the standard of care based on the TOPAZ 1 phase 3 trial that included 171 patients with gallbladder cancer (25%). Overall, median survival is 10–12 months in advanced cases. Second-line therapy includes FOLFOX chemotherapy. Percutaneous transhepatic drainage is indicated in case of biliary obstruction. Radiotherapy is not effective. PART 4 Oncology and Hematology ■ ■OTHER MALIGNANT LIVER TUMORS Fibrolamellar Hepatocellular Carcinoma  Fibrolamellar hepa­ tocellular carcinoma (FLC) is a rare form of primary liver cancer that typically affects children and young adults (10–30 years of age) with­ out background liver disease. FLC accounts for 0.85% of all primary hepatic malignancies in the United States, and its incidence rate is 0.02 cases per 100,000 inhabitants. FLC is considered a unique entity with a specific fusion oncogene PRKACA-DNAJB1 present in 80–100% of cases. Few additional mutations have been described in <10% of cases. FLC has a better prognosis than HCC, probably due to the absence of cirrhosis and the earlier age of presentation. Surgical resection is the mainstay of treatment, and indications are less restrictive than for HCC. A retrospective series of 575 FLC cases reported a median survival of 70 months after resection. At advanced stages, the expected outcome is <20 months. There is no standard systemic therapy, and clinical trials are focused on targeting the fusion protein with kinase inhibitors or immunomodulatory agents. Hepatoblastoma  Hepatoblastoma (HB) is the most frequent pri­ mary liver tumor in children. The incidence of the disease is 1.5 cases per 1,000,000, and onset of the disease occurs before the age of 3 years. Background liver disease is rare in these patients. WNT signaling plays a major role, with CTNNB1 mutations (70%) as the most frequently reported molecular event. Overexpression of IGF2 and genes in the 14q32 DLK1/DIO3 locus is also very prevalent. At diagnosis, ~30% of patients are amenable to surgery. Resection followed by chemo­ therapy with doxorubicin/cisplatin is the mainstay treatment strategy. Among the remaining 70% of patients, neoadjuvant chemotherapy achieved response in >90% of cases and enabled resection with good clinical outcomes. A study including 1605 patients randomized in eight clinical trials reported better outcome for patients with stage I–II of the PRETEXT (Pretreatment Extent of Tumor) classification (out of four stages), age <3 years, AFP >1000 ng/mL, and absence of metastases. As opposed to HCC, low AFP <100 ng/mL indicates poor prognosis. Overall, 5-year survival is 70% (ranging from 50 to 90% depending on PRETEXT stage). BENIGN LIVER TUMORS The most common benign liver tumors are hemangiomas, focal nodu­ lar hyperplasia (FNH), and hepatocellular adenomas (HCA). Most benign tumors are identified incidentally by abdominal ultrasound or other imaging techniques. Hemangiomas are present in ~5% of the general population and are diagnosed by ultrasound except in cirrhotic patients or oncology patients, in whom contrast-enhanced imaging (contrast-enhanced ultrasound, CT, or MRI) is required. Conserva­ tive management is appropriate, and follow-up is not recommended. Exceptionally, growing lesions causing symptoms by compression can be considered for resection. FNH is a benign tumor present in <2% of the population and occurring mostly in females aged 40–50 years. FNH is a polyclonal hepatocellular proliferation due to an arterial mal­ formation. MRI has the highest diagnostic accuracy with a specificity of 100%, when typical imaging features are present (homogeneous enhancement in the arterial phase with a central scar). Atypical FNH requires biopsy for diagnosis. Treatment is not recommended because these tumors do not degenerate or cause complications. In exceptional cases of expanding symptomatic lesions, surgery is the treatment of choice. Hepatic adenomas are clonal benign proliferations resulting from single-gene driver mutations. HCAs have a low prevalence of 0.001% of the population and are frequently diagnosed in women aged 35–40 years. The female-to-male ratio is 10:1, and the main risk factors are oral contraceptives in females and use of anabolic androgenic steroids in male body builders. HCAs have the potential for hemorrhage and HCC development, particularly when >5 cm. Nowadays, there is a clear understanding of the molecular classification of HCA in subtypes defined by CTNNB1 mutations (10–20%), HNF1A inactivation, and activation of inflammatory pathways (50–60%) or Hedgehog signaling pathway. Diagnosis is based on MRI, which is able to correlate with molecular subtypes in 80% of cases (inflammatory and HNF-1A type). For defining HCA with CTNNB1 mutations, biopsy is required. Upon diagnosis, discontinuation of oral contraceptives and weight loss are recommended. Resection is indicated in all cases >5 cm, in men, or with CTNNB1 mutation. For HCA <5 cm, 1-year follow-up is recom­ mended. In case of active HCA bleeding, embolization followed by resection is the treatment of choice. The presence of multiple HCAs is common, and guidelines endorse treating them based on the size of the main nodule. ■ ■FURTHER READING EASL-EORTC Clinical Practice Guidelines: Management of hepatocellular carcinoma. J Hepatol 69:182, 2018. EASL-ILCA Clinical Practice Guidelines on the management of intra­ hepatic cholangiocarcinoma. J Hepatol 79:181, 2023. Finn RS et al: Atezolizumab plus bevacizumab in unresectable hepato­ cellular carcinoma. N Engl J Med 382:1894, 2020. Haber PK et al: Evidence-based management of hepatocellular carci­ noma: Systematic review and meta-analysis of randomized controlled trials (2002-2020). Gastroenterology 161:879, 2021. Ilyas SI: Cholangiocarcinoma: novel biological insights and therapeu­ tic strategies. Nat Rev Clin Oncol 20:470, 2023. Llovet JM et al: Hepatocellular carcinoma. Nat Rev Dis Primers 21;7:6, 2021. Llovet JM et al: Locoregional therapies in the era of molecular and immune treatments for hepatocellular carcinoma Nat Rev Gastroen­ terol Hepatol 18:293, 2021. Llovet JM et al: Immunotherapies for hepatocellular carcinoma. Nat Rev Clin Oncol 19:151, 2022. Llovet JM et al: Molecular pathogenesis and systemic therapies for hepatocellular carcinoma. Nat Cancer 3:386, 2022. Oh DY et al: Durvalumab plus gemcitabine and cisplatin in advanced biliary tract cancer. NEJM Evid 1:2022. Singal AG et al: AASLD Practice Guidance on prevention, diagnosis, and treatment of hepatocellular carcinoma. Hepatology 78:1922, 2023. Villanueva A: Hepatocellular carcinoma. N Engl J Med 380:1450, 2019. # 17 - 88 Pancreatic Cancer ### 88 Pancreatic Cancer Eileen M. O’Reilly, Andrew M. Lowy, Daniel D. Von Hoff Pancreatic Cancer Pancreatic cancer is the third leading cause of cancer-related mortality in the United States, with >66,000 Americans diagnosed and >51,000 dying from the disease each year. Pancreatic cancer is projected to be the second leading cause of death from cancer in the United States by 2030. Worldwide, pancreatic cancer is the eleventh most common can­ cer, with about half a million diagnoses per annum. Pancreatic cancer is the most lethal human cancer, with an overall 5-year survival of 13%. However, that situation is changing. In particular, (1) an enhanced understanding of the pathobiology and genomic landscape of pancre­ atic cancer is steadily giving rise to new therapeutic opportunities, (2) the integration of multimodality therapy for patients with localized disease has improved outcomes, and (3) increasingly more molecularly defined groups of patients are eligible for targeted therapy beyond cytotoxic therapy. ■ ■EPIDEMIOLOGY Pancreatic cancer accounts for 3% of all new cancer cases in the United States and ~8.3% of all deaths from cancer in the United States. The lifetime risk of developing pancreatic cancer is ~1.7%; however, the incidence has been increasing about 1.1% per year overall, but notably in people <55 years of age, it has been increasing 2.36% per year in women and 0.62% per year in men. Pancreatic cancer is more common with increasing age and slightly more common in men than in women. The 5-year survival rate for all stages has increased from 3% in 1975 to 13% in 2024. The latest information from the U.S. Surveil­ lance, Epidemiology, and End Results (SEER) database predicts that the 5-year survival is about 44% for patients with localized pancreatic cancer, 16% for those with regional disease, and 3.2% for patients with metastatic disease. Pancreatic cancer is more common in developed countries (although it tracks with the prevalence of smoking). The inci­ dence is highest in Eastern (e.g., Hungary and Slovakia) and Western (e.g., Germany) Europe and North America followed by other areas in Europe, Australia, New Zealand, and Southcentral Asia. ■ ■RISK FACTORS Age is one of the strongest risk factors for pancreatic cancer with median age at diagnosis of 71 years (the disease is most frequently diagnosed in the 65–79 age group; for men, 65–69; for women, 75–79). The number of new cases per 100,000 persons and the number of deaths per 100,000 persons are higher for males and for black people of both sexes. People who have a non-O blood type are at higher risk of developing pancreatic cancer. Environment  The greatest risk factor for pancreatic cancer is cigarette smoking. The risk correlates with the increased number of cigarettes smoked and persists for at least 10 years following smoking cessation. Twenty-five to 30% of pancreatic cancers are believed to be caused by smoking. Exposure to cadmium as part of cigarette smoking or via exposure to welding, soldering, or dietary exposure has been weakly associated with an increased risk of pancreatic cancer. Dietary factors may contribute to risk, acknowledging confound­ ing issues; however, high intake of fat or meat (particularly well-done barbequed meat) are risk factors. High intake of citrus fruits and veg­ etables are associated with a decreased risk of pancreatic cancer. Coffee and low-to-moderate alcohol consumption are not associated with an increased risk for pancreatic cancer, although consumption of sugary carbonated drinks has been associated with elevated risk. Hereditary Factors, Genetics, and Screening  Hereditary fac­ tors account for 10–16% of all pancreatic cancers. Family members of patients with pancreatic cancer and selected individuals with certain pathogenic germline variants should seek participation in an early detection program with genetic counseling, definition of risk, and if appropriate, periodic magnetic resonance imaging (MRI) screening and endoscopic ultrasound of the pancreas, ideally enrolled on a pro­ spective registry. Table 88-1 summarizes the various germline variants along with familial cancer syndromes where there is known to be an increased risk for pancreatic cancer. For an average-risk individual (without any known predisposing factors), there is currently no recom­ mended screening. Knowing that an individual carries a BRCA1/2 or PALB2 germline variant or any of the above mutations requires referral of that person to an early detection or high-risk screening clinic. For patients with a BRCA1/2 or PALB2 pathogenic germline variant, a poly(ADP-ribose) polymerase (PARP) inhibitor should be considered (see below) as part of treatment for metastatic pancreatic cancer. Other pathogenic germline variants are under study to determine their increased risk of pancreatic cancer, including CFTR, PRSS2, CDK4, FANCC, APC, ATM, BRIP1, BRCA1, EPCAM, MEN1, MLH1, MSH2, MSH6, NF1, PMS2, SMAD4, TP53, TSC1, TSC2, and VHL. Some of these variants are also associated with pancreatic neuroendocrine tumors (Chap. 89). In addition to recognized genetic syndromes from single gene vari­ ants, other individuals without any of these identifiable germline vari­ ants may be at higher risk for this cancer. For example, a family history of pancreatic cancer is associated with increased risk based on the number of affected relatives. Having one first-degree relative with pan­ creatic cancer, one’s risk for developing the disease is increased 4.6-fold, having two first-degree relatives increases the risk 6.4-fold, and three or more first-degree relatives confers a 32-fold increased risk. The risk is also increased if a relative developed pancreatic cancer at <55 years old and is further compounded by smoking. CHAPTER 88 Pancreatic Cancer Medical Conditions  Chronic pancreatitis that is nonfamilial is associated with an increased risk of pancreatic cancer (2.3–16.5-fold increase). Risk is also increased in people with chronic pancreatitis associated with cystic fibrosis or tropical pancreatitis. A clear association exists between diabetes mellitus (both type 1 and type 2) and pancreatic cancer. Whether this is a causal association or whether the diabetes is the result of the cancer is not exactly clear. Newonset (particularly with concomitant weight loss) or unexpected wors­ ening of type 2 (or type 3c) diabetes may be associated with pancreatic cancer, and research programs are evaluating screening in otherwise healthy individuals in this setting. High body mass index (BMI) is considered a risk factor for pancre­ atic cancer. A high BMI of ≥30 is associated with a doubling of pancre­ atic cancer risk. As obesity is a risk factor for diabetes, the contribution of obesity alone is unclear. Interestingly, patients with severe obesity TABLE 88-1  Germline Mutations, Familial Cancer Syndromes, and Fold Risk of Pancreatic Cancer ESTIMATED INCREASED RISK (FOLD) OF PANCREATIC CANCER FAMILIAL CANCER SYNDROME GERMLINE MUTATION BRCA2 a Familial breast/ovarian cancer and others 3.5–10 PALB2 (partner and localizer of BRCA2) Familial breast cancer and others ~Sixfold p16/CDKN2A Familial atypical multiple mole melanoma (FAMMM) 15–22 STKII (LKB1) Peutz-Jeghers syndrome 76–140 PRSS1 or SPIN11b Hereditary (familial) pancreatitis ATM Ataxia-telangiectasia 6c MLH1, MSH2, MSH6, PMS2 Heredity nonpolyposis colorectal syndrome or Lynch syndromed 9–36 aParticularly common in individuals with Ashkenazi Jewish heritage. bForty percent chance of pancreatic cancer by the age of 70. cCalculated at age 70. dVery important because this is associated with microsatellite instability, which is a marker for response to immune checkpoint blockade. who undergo a bariatric intervention experience a reduction in the incidence of gastrointestinal cancers, including pancreatic cancer, by >30% in the first 3 years (along with a decrease in their hemoglobin A1c and blood glucose level). Physical inactivity also has been associated with an increased risk of pancreatic cancer. Other Considerations  Most patients with pancreatic cancer relate that they have had developing symptoms over months to years before diagnosis. Efforts at early detection of the disease have not yet been fruitful, but this is an area of very active investigation. ■ ■PATHOLOGY AND MOLECULAR CONSIDERATION Location  The posterior location of the pancreas in the abdomen is one of the issues that makes diagnosis more challenging (Fig. 88-1A). Pathology  Cancers of the pancreas can be divided into neoplasms of the endocrine pancreas (Chap. 89) and those of the exocrine pan­ creas. The most common neoplasm of the exocrine pancreas and most lethal is ductal adenocarcinoma. These cancers arise in the head, body, or tail of the pancreas and are characterized by infiltrating desmoplas­ tic stromal reactions (Fig. 88-1B). Other subtypes of nonneuroendocrine pancreatic cancers include acinar cell carcinoma (tumors of the exocrine enzyme producing cell), colloid carcinoma, medullary carcinoma, adenosquamous carcinoma, and other rare subtypes. Each of these is different in behavior and in their molecular characteristics and often requires other specific types of treatment. Occasionally, metastases to the pancreas occur second­ ary to renal, breast, lung, and urothelial carcinomas, melanoma, lym­ phoma, and other malignancies. PART 4 Oncology and Hematology Molecular Characteristics  The mutational landscape of pan­ creatic ductal adenocarcinoma is characterized by alterations in four genes that are commonly mutated or inactivated. The most common of these is the KRAS oncogene (mutations primarily in codon 12). It is increasingly important to identify the specific mutant KRAS allele as novel drugs targeting specific alleles now exist and others are in development. KRAS mutations are seen in 90–95% of pancreatic adenocarcinomas. A subset of pancreatic cancers is termed “KRAS Stomach Splenic artery Hepatic artery Portal vein Spleen Common bile duct Kidney Jejunum Pancreas Duodenum Superior mesenteric artery Superior mesenteric vein A FIGURE 88-1  A. Note the relationship of the pancreas to the major vessels of the retroperitoneum. B. Ductal adenocarcinoma of the pancreas (black arrows), with intense stromal component (white arrows). (Part A is courtesy of Mary Kay Washington, MD, PhD, Vanderbilt University. Part B is courtesy of Haiyong Han, PhD, Translational Genomics Research Institute [TGen].) wildtype,” where no alteration in KRAS is observed. This form of pancreatic cancer is more frequently observed in patients <55 years of age, and often other therapeutically actionable findings are identi­ fied in these cancers, including mutations in BRAF, rare oncogenic targetable fusions (e.g., NRG-1, NTRK1-3), or microsatellite instability. p16/CDKN2A mutation or epigenetic silencing is present in >90% of invasive pancreatic adenocarcinomas. TP53 is mutated in ~75% and DPC4/SMAD4 is mutated in about half of these tumors. As a reference point, the BRCA2 gene noted in Table 88-1 is mutated in 3.5–10% of pancreatic adenocarcinomas. Precursor Lesions  Most pancreatic cancers are believed to arise from pancreatic intraepithelial neoplasia (PanINs), which have vary­ ing degrees of dysplasia designated as PanINs 1–3 (and constitute a progression model for pancreatic cancer). Genetic alterations become more frequent as the PanIN grade increases (e.g., grade 3). Most PanIN lesions will never progress to invasive malignancy. An alternate precursor lesion is an intraductal papillary neoplasm (IPMN), which is usually noninvasive. Unfortunately, even high-grade PanIN lesions are not detectable by currently available imaging modalities. In con­ trast, some pancreatic adenocarcinomas arise from noninvasive cystic epithelial precursor lesions. These lesions can be seen on magnetic resonance imaging (MRI) and computed tomography (CT) imaging, and thus detection may permit early diagnosis of pancreatic cancer. As compared to main pancreatic duct IPMN, a side branch duct IPMN is more likely to be noninvasive. MRI and endoscopic ultrasound are commonly used to assess malignant potential based on risk factors such as size, growth rate, main pancreatic duct size, and the presence of mural nodularity. One other rare pancreatic tumor is the mucinous cystic neoplasm; they may be seen as incidental findings on scans and are more com­ mon in the body and tail of the pancreas and tend to occur in women. These lesions are less likely to progress to malignancy. Clinical signs of concern include large size (>3 cm) and the presence of mural nodules and/or thickening. Even after rare progression to mucinous adeno­ carcinoma, they typically have a more favorable prognosis relative to typical ductal adenocarcinoma. B A B C D E F FIGURE 88-2  Selected images from contrast-enhanced computed tomography (CT) in patients with locally advanced adenocarcinoma of the pancreas. A high-quality contrast-enhanced CT scan (arterial phase in panels A–C and portal venous phase in panels D–F) is required for optimal staging of pancreas cancer. Panel A demonstrates the typical features of adenocarcinoma of the pancreas on arterial phase axial CT scans (dotted outline) with tumor encasement of the superior mesenteric artery (white arrow). Note the dilatation of the common bile duct (red arrow). Panels B (magnified coronal) and C (sagittal) show reconstruction of CT images into additional orthogonal planes with exquisite details to confirm the unresectable nature of the tumor due to vascular encasement. Panel D demonstrates the typical features of adenocarcinoma of the pancreas on portal venous phase axial CT scans in a different subject. The dotted line outlines a pancreas cancer lesion in the pancreatic head, which is encasing the portal splenic confluence (dotted outline). Panels E (white arrow) and F show the pinched appearance of the portal splenic confluence by tumor abutment and invasion of the superior mesenteric vein (white arrow) on coronal and sagittal views. Note the presence of a stent in the common bile duct (red arrow) to help relieve biliary obstruction caused by the tumor. CA, celiac axis; SMA, superior mesenteric artery. ■ ■CLINICAL FEATURES History and Physical  A classic presentation for a patient with pancreatic cancer arising in the head of the gland is “painless” jaundice. Jaundice is visually detectable with a bilirubin of >2 mg/dL, and pruritus may also occur due to bile salt deposition in the skin. However, pain is also common in newly diagnosed patients and is typically mid epigas­ tric (sometimes described as a “boring-like” pain) with radiation to the back (due to retroperitoneal invasion of the splanchnic nerve plexus). The pain may be exacerbated by eating or lying flat. In the presence of jaundice, light stool color from the absence of bile occurs (steatorrhea also causes malodorous stools). Other signs include the onset of diabetes (particularly with concomitant weight loss) or hyperglycemia/elevated hemoglobin A1c in the preceding 1–2 years. The association of pancreatic cancer with depression remains controversial. In addition to jaundice, physical signs of pancreatic cancer include evidence of weight loss, including loss of muscle mass, and a palpable gallbladder in the setting of biliary obstruction (Courvoisier’s sign). Migratory superficial thrombophlebitis and presentation with both deep venous and arterial thromboses can occur (Trousseau’s syndrome). Signs of late-stage disease include a lymph node palpable in the supraclavicu­ lar fossa (usually on the left where the thoracic duct enters the subcla­ vian vein). This is referred to as Virchow’s node. Occasionally, one can palpate subcutaneous metastases in the periumbilical area referred to as a Sister Mary Joseph’s node—named after one of the operating room nurses from the Mayo Clinic who noted that when she prepped that area and felt those nodules, the patient often had peritoneal metastases. The history and symptoms noted above lead to imaging as the next step, including ultrasonography (jaundice) and CT or MRI. ■ ■DIAGNOSTIC WORKUP Imaging  A key diagnostic tool is the use of a dual-phase con­ trast-enhanced CT using a pancreas cancer protocol, which allows CHAPTER 88 Pancreatic Cancer arterial phase enhancement and portal venous phase enhancement and detailed visualization of tumor–blood vessel relationships to inform both resectability and staging. Figure 88-2 demonstrates such a CT scan (with vascular involvement). Figure 88-3 demonstrates the use of an 18F-glucose positron emission tomography (PET) scan that can aid in the detection of otherwise occult metastatic disease. FIGURE 88-3  Positron emission tomography scan demonstrating metastatic disease—baseline and after 6 weeks of chemotherapy with partial resolution of liver metastases. Histologic Diagnosis  A histologic (tissue) diagnosis is essential and should be obtained with a Tru-Cut biopsy needle (fine-needle aspi­ ration cytology is an acceptable but less preferred alternative). Obtain­ ing adequate tissue not only secures a histologic/cytologic diagnosis but also facilitates molecular testing (next-generation sequencing for genomic alterations including KRAS) and microsatellite status. Increas­ ingly subsets of patients based on genomic characterization are being identified and for whom therapies are available, making the need for adequate tissue sampling increasingly relevant to patient management. A core needle (18- to 22-gauge) biopsy can be obtained via endo­ scopic ultrasound-guided technique for a tumor localized to the pan­ creas. To biopsy the liver or a lymph node, a larger (16- to 18-gauge) percutaneous needle biopsy by an interventional radiologist is typically undertaken. Serum Markers  Before treatment and, ideally, once the bilirubin level has normalized (biliary obstruction is associated with elevated CA19-9), a serum sample should be obtained for level of CA19-9, carcinoembryonic antigen (CEA), and CA125 (can be helpful for the 8–15% of patients with nondetectable CA19-9–Lewis antigen nonse­ cretors). Trends of these tumor markers over time can inform thera­ peutic decision-making. ■ ■IMPORTANT IMMEDIATE CONSIDERATIONS IN PATIENT CARE During the life cycle of this cancer, biliary tract obstruction is a fre­ quent occurrence for tumors arising in the head of the gland (and the attendant risk for sepsis from the biliary tree). A metallic biliary wall stent is typically placed endoscopically to alleviate jaundice and pru­ ritus. If surgery is under consideration as the initial therapeutic step, biliary stent placement is not necessarily warranted; however, if neo­ adjuvant (preoperative) systemic therapy is planned, both a histologic/ cytologic diagnosis and placement of a biliary wall stent are required (where the latter is medically indicated). Of important note, all patients with localized pancreatic cancer require multidisciplinary evaluation by surgical, medical, and radiation oncology to optimize therapeutic decision-making. PART 4 Oncology and Hematology Patients with metastatic pancreatic cancer may have a hyperco­ agulable state and frequently have thrombophlebitis (Trousseau’s sign) and deep vein thrombosis with pulmonary emboli and/or more rarely arterial thrombotic events. Anticoagulation using either a direct oral anticoagulant or low-molecular-weight heparin is required in these setting in the absence of a contraindication to anticoagulation. Control of pain or of active cancer-related symptomatology includ­ ing anorexia, weight loss, and malabsorption should be proactively treated. Pancreatic enzyme replacement therapy (PERT) is a critical measure to address symptoms of malabsorption, including abdominal cramping, bloating, steatorrhea, excess flatus, and weight loss. Early involvement of a supportive care team can help maximize symptom control, facilitate treatment readiness, and extend a better quality of life. ■ ■CLINICAL STAGING The clinical staging of pancreatic cancer according to the American Joint Commission on Cancer staging is presented in Table 88-2. Table 88-3 presents another clinical way to express extent of disease as well as therapeutic approaches (to be discussed later). For optimal staging, a laparoscopy is selectively indicated either before or at the time of definitive surgery. If metastatic disease is identi­ fied at laparoscopy, curative intent surgery is not undertaken. TREATMENT Pancreatic Cancer RESECTABLE DISEASE (10–20%) For all patients with localized pancreatic cancer, multidisciplinary evaluation should be undertaken. A standard approach for resect­ able disease (10–15% of patients; as defined in Table 88-3) is upfront surgery. Neoadjuvant therapy (systemic therapy prior to surgery) is an option for patients with resectable disease. The ratio­ nales for preoperative chemotherapy include the following: (1) to control micrometastatic disease; (2) to assess tumor biology and response to the selected chemotherapy regimen (this allows patients with progressive disease to avoid nontherapeutic, morbid surgery); (3) to assure delivery of systemic therapy because therapy is better tolerated in the preoperative setting and is not subject to omission of drugs or altering doses due to delayed postoperative recovery; and (4) to achieve tumor downstaging to enhance the potential for a margin-negative surgical resection. The type of surgery for patients with tumors in the pancreatic head, neck, or uncinate process is typically a pancreaticoduodenectomy with or without pylorus preservation. For tumors in the body or tail, a distal subtotal pan­ createctomy and splenectomy are performed. These operations may be performed using a traditional “open” surgical technique or using minimally invasive techniques. Clinical and pathologic findings of the resection are defined as either an R0 resection (no macroscopic or microscopic disease left after surgery) or an R1 resection, which refers to microscopic residual disease at the surgical margin. An R2 resection refers to gross residual disease remaining after surgery and is a highly undesirable oncologic outcome. The best outcomes are achieved in patients with a small tumor (<2 cm), no lymph node involvement (N0), and R0 (stage I), in whom 5-year survival ranges from 50 to 90% depending on actual tumor size and grade. Overall, only a small fraction of tumors are diagnosed when stage I; however, a key goal of screening is to “stage migrate” and increase the proportion of tumors that are diagnosed as early stage I lesions. Several approaches are designed to maximize outcome for local­ ized pancreatic cancer. Postoperative Adjuvant Therapy  A standard of care is 24 weeks of adjuvant treatment with the modified FOLFIRINOX regimen (folinic acid, 5-fluorouracil, irinotecan, oxaliplatin). The median survival was 54 months for modified FOLFIRINOX compared to 35 months for gemcitabine alone (hazard ratio [HR] 0.64; 95% confidence interval [CI] 0.48–0.86; p = .003) in the definitive trial supporting this therapy. Main side effects included fatigue, gastro­ intestinal toxicity, myelosuppression, and neuropathy. Neoadjuvant Therapy  A newer approach is the use of neoadjuvant chemotherapy (systemic therapy given before surgery) to shrink the tumor, eradicate micrometastatic disease, and normalize serum CA19-9 level. Neoadjuvant therapy is the standard approach for patients with borderline resectable or locally advanced disease. The role of radiation in the treatment of localized pancreatic cancer is controversial. LOCALLY ADVANCED DISEASE (25–30% OF PATIENTS)  For patients with locally advanced disease (defined by tumor contact with arterial structures >180° and/or venous contact that does not permit resection/reconstruction), the median survival is poor (6–18 months). Complications from local disease progression can be significant and include pain, biliary and duodenal obstruc­ tion, vascular thromboses, varices, bleeding, and infection/sepsis. Typical treatment paradigms for locally advanced disease include systemic chemotherapy with or without radiation therapy. A pro­ portion of patients with locally advanced disease (~20%) may be rendered operable following neoadjuvant therapy. METASTATIC DISEASE (50–60% OF PATIENTS)  The mainstay of treatment for metastatic pancreatic cancer is systemic chemotherapy. Several treatment regimens including FOLFIRINOX, gemcitabine, albumin-bound paclitaxel, and, more recently, NALIFIRINOX (nanoliposomal irinotecan, 5-fluorouracil, leucovorin, oxaliplatin; NAPOLI-3) have all demonstrated a survival advantage compared to prior standards in untreated metastatic pan­ creatic cancer. In a previously treated setting, liposomal irinotecan and infusional 5-fluorouracil and leucovorin (NAPOLI-1) regimen has been shown to improve survival. Predictors of outcome in the TABLE 88-2  Definition of Primary Tumor (T) T CATEGORY T CRITERIA TX Primary tumor cannot be assessed T0 No evidence of primary tumor Tis Carcinoma in situ This includes high-grade pancreatic intraepithelial neoplasia (PanIn-3), intraductal papillary mucinous neoplasm with high-grade dysplasia, intraductal tubulopapillary neoplasm with high-grade dysplasia, and mucinous cystic neoplasm with high-grade dysplasia T1   T1a   T1b   T1c Tumor ≤2 cm in greatest dimension Tumor ≤0.5 cm in greatest dimension Tumor >0.5 cm and <1 cm in greatest dimension Tumor 1–2 cm in greatest dimension T2 Tumor >2 cm and ≤4 cm in greatest dimension T3 Tumor >4 cm in greatest dimension T4 Tumor involves celiac axis, superior mesenteric artery, and/or common hepatic artery, regardless of size N CATEGORY N CRITERIA NX Regional lymph nodes cannot be assessed N0 No regional lymph node metastases N1 Metastasis in one to three regional lymph nodes N2 Metastasis in four or more regional lymph nodes M CATEGORY M CRITERIA M0 No distant metastasis M1 Distant metastasis AJCC Prognostic Stage Groups WHEN T IS… AND N IS… AND M IS… THEN THE STAGE GROUP IS…. Tis N0 M0 T1 N0 M0 IA T1 N1 M0 IIB T1 N2 M0 III T2 N0 M0 IB T2 N1 M0 IIB T2 N2 M0 III T3 N0 M0 IIA T3 N1 M0 IIB T3 N2 M0 III T4 Any N M0 III Any T Any N M1 IV Source: Used with permission of the American College of Surgeons, Chicago, Illinois. The original source for this information is the AJCC Cancer Staging System (2023). TABLE 88-3  Extent of Disease and Therapeutic Approach DESIGNATION (MEDIAN SURVIVAL) THERAPEUTIC APPROACHES 1. Resectable (localized): (18–23 mo) Surgery followed by adjuvant therapy • mFOLFIRINOX or gemcitabine +/– • No solid tumor contact with celiac axis, hepatic artery, or superior mesenteric artery (SMA), contact with superior mesenteric–portal veins of <180° • Patent superior mesenteric–portal capecitabine or nab-paclitaxel Neoadjuvant chemotherapy followed by surgery veins • No extrapancreatic disease 2. Locally advanced: (6–18 mo) Chemotherapy Chemotherapy +/– radiation Evaluate for surgery following systemic therapy • Arterial involvement of >180° (superior mesenteric artery, others) • Venous occlusion (superior mesenteric vein [SMV] or portal) • No extrapancreatic disease 3. Metastatic: (6–12 mo) Chemotherapy with special consideration for tumors with specific targets (e.g., mismatch repair high, BRCA1/2, BRAF, etc.) Abbreviation: mFOLFIRINOX, modified FOLFIRINOX (folinic acid, 5-fluorouracil, irinotecan, and oxaliplatin (T Conroy et al: N Engl J Med 379:2395, 2018). CHAPTER 88 Pancreatic Cancer metastatic setting include good physical functioning (performance status), favorable nutritional status, the absence of liver metastases, lung-only metastases, and the presence of select pathogenic germ­ line variants. Table 88-4 details combination regimens that have further improved survival modestly. Median overall survival ranges from 6 to 12 months. However, 1-year survival is improving, with subsets of patients whose survival with metastatic disease can reach a couple of years or longer. PATIENTS WITH A SPECIFIC MOLECULAR PROFILE IN THEIR TUMOR/GERMLINE  PARP inhibitors have activity in patients with pathogenic germline or somatic (tumor-based) BRCA2, BRCA1, or PALB2 (i.e., defective DNA repair proteins) variants. In addition, these tumors might be more sensitive to specific combinations of chemotherapy that include platinum agents (gemcitabine and cisplatin or FOLFIRI­ NOX). About 1% of pancreatic cancers have microsatellite insta­ bility, typically with high numbers of mutations in their tumors, due to deficient mismatch repair, and these tumors are likely to benefit from immune checkpoint blockade with anti-PD-1 (pem­ brolizumab, nivolumab) and anti-CTLA-4 inhibitors. KRAS muta­ tions occur ubiquitously in pancreatic cancer. Current treatment guidelines include drugs targeting KRAS G12C (~1% of pancreatic # 18 - 89 Gastrointestinal Neuroendocrine Tumors ### 89 Gastrointestinal Neuroendocrine Tumors TABLE 88-4  Combination Chemotherapy Regimens That Have an Impact on Survival in Stage IV Disease NO. OF PATIENTS MEDIAN OVERALL SURVIVAL (MONTHS) STUDY DESIGN (AUTHOR/REF) Gemcitabine + erlotinib vs gemcitabine (Moore et al: J Clin Oncol 26:1960, 2007) 6.24 vs 5.91 (HR 0.82; 95% CI 0.69–0.99; p = .038) FOLFIRINOX (folinic acid + 5-fluorouracil + irinotecan + oxaliplatin) vs gemcitabine (Conroy et al: N Engl J Med 364:1817, 2011) 11.1 vs 6.8 (HR 0.57; 95% CI 0.45–0.70; p <.001) Nab-paclitaxel + gemcitabine vs gemcitabine (Von Hoff et al: N Eng J Med 369:1691, 2013) 8.5 vs 6.7 (HR 0.72; 95% CI 0.62–0.83; p <.001a Nanoliposomal irinotecan, 5-fluorouracil + folinic acid vs nanoliposomal irinotecan monotherapy vs 5-fluorouracil + folinic acid (Wang-Gillam et al: Lancet 387:545, 2015) 6.1 vs 4.2 (HR 0.67; 95% CI 0.49–0.92; p = .012b) NALIRIFOX (nanoliposomal irinotecan, 5-fluorouracil, folinic acid, oxaliplatin) vs nab-paclitaxel and gemcitabine (Wainberg et al: Lancet 402:1272, 2023) 11.1 vs 9.2 (HR 0.83; 95% CI 0.70–0.99; p = .036) aThe 2-year survival rate with this regimen is 9%, and the 3+ year rate is 4%. Other studies have not reported on these parameters. bHR is for nanoliposomal irinotecan + 5-fluorouracil + folinic acid vs 5-fluorouracil + folinic acid. Abbreviations: CI, confidence interval; HR, hazard ratio. PART 4 Oncology and Hematology cancers); however, agents that target more common KRAS muta­ tions (G12D, G12V, G12R) are being evaluated in clinical trials and have high potential to become part of standard treatment algorithms in the future. Other rare actionable alterations include oncogenic fusions in RET, ALK, MET, NRG-1, ROS, and BRAF V600E mutations, for which therapeutic agents are available and are in clinical trials. MAINTENANCE THERAPY FOR PATIENTS RESPONDING TO TREATMENT  For patients with a germline BRCA1 or BRCA2 mutation whose metastatic pancreatic cancer has not grown during an initial plati­ num-based regimen, the PARP inhibitor olaparib has been shown to improve progression-free survival (7.4 vs 3.8 months; HR 0.53; 95% CI 0.35–0.82; p = .004) and maintenance of quality of life, both relative to placebo. ■ ■FUTURE DIRECTIONS Multiple novel therapies are under development in pancreatic cancer. Immunotherapy using personalized neoantigen vaccines or using an antigenic target such as a “public” or shared neoantigen such as KRAS has demonstrated early promise following resection of pancreatic cancer as an adjunct to standard chemotherapy. Mid-phase trials are planned/underway to further explore these signals. KRAS has hereto­ fore been considered nondruggable; however, developments in organic chemistry, biosynthesis, and other innovations have led to a series of therapeutics directly targeting KRAS with promise that these agents in the proximate future will be integrated as part of standard therapy for pancreatic cancer. Multiple therapeutic approaches targeting the tumor immune microenvironment are being explored, capitalizing on an increased understanding of the pathobiology of this cancer. Other important developments include innovation in clinical trial design, novel approaches to screening and surveillance utilizing “liquid” bio­ markers (incorporating DNA fragments, methylation, and proteomic profiles), and other technologic developments. Acknowledgment Thank you to the American Joint Committee on Cancer for providing the tables. ■ ■FURTHER READING Conroy T et al: FOLFIRINOX versus gemcitabine for metastatic pancreatic cancer. N Engl J Med 364:1817, 2011. Conroy T et al: FOLFIRINOX or gemcitabine as adjuvant therapy for pancreatic cancer. N Engl J Med 379:2395, 2018. Golan T et al: Maintenance olaparib for germline BRCA-mutated metastatic pancreatic cancer. N Engl J Med 381:317, 2019. Hu ZI, O’Reilly EM: Therapeutic developments in pancreatic cancer. Nat Rev Gastroenterol Hepatol 21:7, 2024. Hruban RJ et al: Genetic progression in the pancreatic ducts. Am J Pathol 156:1821, 2000. Park W et al: Pancreatic cancer: A review. JAMA 326:851, 2021. Rahib L et al: Evaluation of pancreatic cancer clinical trials and benchmarks for clinically meaningful future trials: A systemic review. JAMA Oncol 2:1209, 2016. Rawla P et al: Epidemiology of pancreatic cancer: Global trends, etiology, and risk factors. World J Oncol 10:10, 2019. Solomon S et al: Inherited pancreatic cancer syndromes. Cancer J 18:485, 2012. Von Hoff D et al: Increased survival in pancreatic cancer with nabpaclitaxel plus gemcitabine. N Engl J Med 369:1691, 2013. Wainberg Z et al: NALIRIFOX versus nab-paclitaxel and gemcitabine in treatment-naive patients with metastatic pancreatic ductal adeno­ carcinoma (NAPOLI 3): A randomised, open-label, phase 3 trial. Lancet 402:1272, 2023. Yuan C et al: Diabetes, weight change, and pancreatic cancer risk. JAMA Oncol 6:e202948, 2020. Matthew H. Kulke Gastrointestinal Neuroendocrine Tumors Gastrointestinal (GI) neuroendocrine tumors (NETs) can be broadly grouped according to their site of origin as either extrapancreatic NETs, historically called carcinoid tumors, or pancreatic NETs. While NETs can pursue a broad range of clinical behaviors, they classically follow a course that is more indolent than many other malignancies. NETs also have the ability to synthesize peptides, growth factors, and bioactive amines that may be ectopically secreted, giving rise to a range of unique clinical syndromes. INCIDENCE AND PREVALENCE The diagnosed incidence of NETs has been steadily increasing over the past several decades. An analysis of data from the Surveillance, Epidemi­ ology, and End Results (SEER) program, comprising population-based data in the United States from 1973 to 2012, showed that the overall inci­ dence had increased 6.4-fold over this time period and that the estimated prevalence of patients who had been diagnosed with a NET was >170,000. Gastroenteropancreatic neuroendocrine tumors comprise the majority of neuroendocrine tumors, and recent analyses suggest the incidence in this subgroup has risen proportionately and continues to rise (Fig. 89-1). These same studies have also found that overall survival durations for patients with NETs have improved significantly over time. The increasing incidence and improved survival durations for patients with NETs likely reflect, at least in part, advances in both diagnosis and treatment. While environmental or other factors leading to an increased inci­ dence of NETs cannot be excluded, common cancer risk factors such as tobacco or alcohol use and dietary patterns have not been clearly linked to NET development. A minority of NETs develop in the context of autosomal inherited genetic syndromes associated with mutations in specific tumorsuppressor genes. The most common of these is multiple endocrine neoplasia type 1 (MEN 1), due to mutation and loss of function of the menin gene, located on chromosome 11q13 (Chap. 400). Patients Age adjusted incidence of neuroendocrine tumors in U.S. (per 100,000) Age adjusted incidence of all malignancies in the U.S. (per 100,000) A B FIGURE 89-1  Incidence of gastroenteropancreatic neuroendocrine tumors (NETs). The incidence of gastroenteropancreatic neuroendocrine tumors has been increasing over the past several decades, an observation that has been attributed in part to improved diagnosis and classification. (Adapted from Z Xu et al: Epidemiologic trends of and factors associated with overall survival for patients with gastroenteropancreatic neuroendocrine tumors in the United States. JAMA Network Open 4:e2124750, 2021, Figure 1A.) with MEN 1 are at risk for developing pancreatic NETs as well as hyperparathyroidism and pituitary adenomas; less commonly, they may develop bronchial and thymic NETs. Other inherited syndromes associated with NETs include von Hippel–Lindau disease (VHL), von Recklinghausen’s disease (neurofibromatosis type 1), and tuberous sclerosis (Bourneville’s disease). Inherited mutations in the VHL gene, located on chromosome 3p25, are associated with the development of cerebellar hemangioblastomas, renal cancer, and pheochromocytomas and, less commonly, pancreatic NETs. Mutations in neurofibromin (NF1) are associated with neurofibromatosis (von Recklinghausen’s disease); patients with neurofibromatosis are at risk of developing both pancreatic and extrapancreatic NETs. Tuberous sclerosis is caused by mutations that alter either hamartin (TSC1) or tuberin (TSC2). Both hamartin and tuberin function as inhibitors of the phosphatidylinositol 3-kinase and the mechanistic target of rapamycin (mTOR) signaling cascades, and pancreatic NETs have been reported in these patients. Rare cases of familial small intestine NETs have also been reported; in these cases, multiple synchronous tumors generally arise within the small intestine. A characteristic inherited mutation has not been iden­ tified to date in the majority of these cases. HISTOLOGIC CLASSIFICATION AND MOLECULAR FEATURES The histologic features of NETs vary widely and are one of the most important determinants of both clinical behavior and treatment. NETs are classified based on the degree tumor differentiation (well or poorly TABLE 89-1  Histologic Classification of Neuroendocrine Tumors CLASSIFICATION DIFFERENTIATION GRADE MITOTIC COUNT KI-67 Neuroendocrine tumor Well differentiated Low grade (grade 1) <2 per 10 HPF <3% Neuroendocrine tumor Well differentiated Intermediate grade (grade 2) 2–20 per 10 HPF 3–20% Neuroendocrine tumor Well differentiated High grade (grade 3) >20 per 10 HPF >20% Neuroendocrine carcinoma Poorly differentiated High grade (grade 3) >20 per 10 HPF >20% Abbreviation: HPF, high-power field. differentiated), as assessed by a pathologist, and tumor grade (grades 1–3) (Table 89-1). Tumor grade closely correlates with mitotic count and Ki-67 proliferative index. Classic, well-differentiated NETs are composed of monotonous sheets of small round cells with uniform nuclei and only rare mitoses. Immunocytochemical staining for chromogranins and synaptophysin is typical. Ultrastructurally, these tumors contain electron-dense neurosecretory granules containing peptides and bio­ active amines that may be ectopically secreted, giving rise to a range of clinical syndromes. These classic well- differentiated NETs have low-grade features and gener­ ally have a mitotic index of <2 mitoses per 10 high-power fields (HPFs) and a Ki-67 proliferative index of <3%. Less commonly, well-differentiated NETs have an intermedi­ ate histologic grade and pursue a somewhat more aggres­ sive clinical course. Intermediate-grade tumors typically have a mitotic count of 2–20 per 10 HPF and a mitotic index of 3–20%. Well-differentiated high-grade tumors are rare and have mitotic counts that exceed 20 per 10 HPF and a Ki-67 proliferative index of >20%. Poorly dif­ ferentiated high-grade tumors form the most clinically aggressive category; prognosis and treatment for these tumors differ markedly from their well-differentiated counterparts. CHAPTER 89 Whole exome sequencing of sporadic pancreatic NETs has shown that the most frequently altered gene was MEN1, occurring in 44% of tumors. In addition, 43% of tumors had mutations in genes encoding two sub­ units of a transcription/chromatin remodeling complex consisting of DAXX (death-domain-associated protein) and ATRX (α-thalassemia/mental retardation syndrome X-linked). Mutations in genes associated with the mTOR pathway were identified in 15% of tumors. In contrast, recurrent mutations in extrapancreatic NETs appear to be rare. In one study that evaluated 180 small intestinal NETs using a combination of whole exome and more targeted genome-sequencing analysis, recurrent mutations were only observed in the CDKN1B gene (cyclin-dependent kinase inhibitor 1B [p27Kip1]) in 8% of cases. Loss of chromosome 18 is a common finding in small-bowel NETs. Small-intestinal GI carcinoids commonly have epigenetic changes; however, the clinical significance of these alterations remains uncertain. Gastrointestinal Neuroendocrine Tumors CLINICAL PRESENTATION AND MANAGEMENT OF LOCALIZED PANCREATIC NEUROENDOCRINE TUMORS Pancreatic NETs have been subcategorized as either “functional,” meaning associated with symptoms of hormone secretion, or non­ functional, in which case they may be clinically silent until they cause anatomic symptoms. The clinical presentation of functional pancreatic NETs depends on the type of hormone secreted and can sometimes lead to dramatic clinical presentations (Table 89-2). The most com­ mon functional pancreatic NETs are insulinomas, followed in inci­ dence by glucagonomas and gastrinomas. Pancreatic NETs secreting other hormones, including somatostatin, vasoactive intestinal pep­ tide (VIP), adrenocorticotropic hormone (ACTH), and parathyroid hormone (PTH), have also been described but are uncommon. Only ~20% of pancreatic NETs are associated with symptoms of hormone TABLE 89-2  Clinical Presentation and Management of Secretory Syndromes Associated with Neuroendocrine Tumors TREATMENT OPTIONS TO CONTROL SECRETORY SYMPTOMS CLINICAL SYMPTOMS AND MANIFESTATIONS Pancreatic Neuroendocrine Tumors Gastrinoma (generally located in “gastrinoma triangle”) Zollinger-Ellison syndrome: gastroesophageal reflux, peptic ulcer disease, diarrhea Proton pump inhibitors, somatostatin analogues Insulinoma Hypoglycemia leading to confusion, lethargy, coma; weight gain Diazoxide, everolimusa Glucagonoma Skin rash (necrolytic migratory erythema), glucose intolerance, weight loss Somatostatin analogues VIPoma Verner-Morrison syndrome: watery diarrhea, hypokalemia, achlorhydria Somatostatin analogues ACTHoma Cushing’s syndrome: hyperglycemia, weight gain, hypokalemia Ketoconazole, metyrapone, consider adrenalectomy PART 4 Oncology and Hematology Extrapancreatic Gastrointestinal Neuroendocrine Tumors Typically in setting of advanced disease from small intestine or appendiceal primary tumors Carcinoid syndrome: flushing, diarrhea, rightsided valvular heart disease, mesenteric fibrosis Somatostatin analogues, telotristat ethyl aSuccessful use of monoclonal anti-insulin receptor antibodies to treat insulininduced hypoglycemia has been reported but remains investigational. Abbreviations: ACTH, adrenocorticotropic hormone; VIP, vasoactive intestinal peptide. hypersecretion; the majority of pancreatic NETs are “nonfunctional” and are diagnosed either incidentally or after patients present with abdominal pain, weight loss, or other anatomic symptoms related to tumor bulk. ■ ■GASTRINOMA Patients with gastrinoma typically present with Zollinger-Ellison syn­ drome (ZES) (Chap. 335). The most common symptoms associated with this syndrome are abdominal pain, diarrhea, gastroesophageal reflux disease (GERD), and peptic ulcer disease. Peptic ulcer disease manifesting as multiple ulcers with associated diarrhea is a classic pre­ sentation. Up to 25% of patients with ZES have MEN 1, and a diagnosis of gastrinoma should prompt a family history as well as an assessment for concurrent hyperparathyroidism. Fasting hypergastrinemia is a nearly universal finding in patients with gastrinoma. Importantly, however, proton pump inhibitors (PPIs) can suppress acid secretion sufficiently to cause hypergastrinemia and can confound the diagno­ sis. Achlorhydria, usually in the context of chronic atrophic gastritis, will also elevate serum gastrin levels but can usually be easily distin­ guished from gastrinoma given the absence of other evidence of acid hypersecretion. While often classified as pancreatic NETs, the majority of gastri­ nomas in fact arise in the “gastrinoma triangle,” an anatomic region bounded by the duodenum, pancreas, and confluence of the cystic and common bile ducts. Most gastrinomas (50–90%) in sporadic ZES arise in the duodenum. They are frequently small and may be dif­ ficult to localize. Imaging studies generally include either computed tomography (CT) or magnetic resonance imaging (MRI); endoscopic ultrasound or somatostatin scintigraphy may also be helpful. PPIs are generally highly effective in the treatment of symptoms related to gastrinoma and are considered the initial treatment of choice. Rapid resolution of both abdominal pain and diarrhea related to acid hypersecretion is common. Somatostatin analogues may also be helpful in controlling symptoms in refractory cases. Once symptoms are con­ trolled, surgical resection is generally recommended for patients with sporadic gastrinomas, both to eliminate the cause of gastrin secretion and to decrease the risk of developing metastatic disease. The tech­ nique used for resection depends in large part on the precise location of the tumor. In some cases where preoperative imaging is not success­ ful but a diagnosis is strongly suspected, exploratory laparotomy with intraoperative ultrasound may be undertaken. In gastrinoma patients who have underlying MEN 1, tumors are generally small and multiple; the role of routine surgery in this setting remains more controversial but generally is still recommended in patients with larger tumors mea­ suring ≥1.5–2 cm in diameter. ■ ■INSULINOMA Patients with insulinoma generally present with symptoms of hypogly­ cemia, which may include confusion, headache, disorientation, visual difficulties, irrational behavior, and even coma. In some cases, the diag­ nosis of insulinoma may not be immediately evident, and patients with insulinoma may initially be diagnosed with psychiatric illnesses that in retrospect were hypoglycemic symptoms. The diagnosis of insulinoma is generally confirmed with elevated fasting insulin levels in conjunc­ tion with elevated proinsulin and C-peptide. Fasting hypoglycemia can also be caused by severe liver disease, alcoholism, and poor nutrition. Postprandial hypoglycemia may also occur after gastric bypass surgery. Surreptitious use of insulin or hypoglycemic agents may be difficult to distinguish from an insulinoma. Evaluation of proinsulin and C-pep­ tide levels, both of which should be normal in patients using exogenous insulin, and measurement of sulfonylurea levels in serum or plasma are helpful in such cases. The hypoglycemia associated with insulinomas can be severe and challenging to manage. While somatostatin analogues are usually effec­ tive in treating symptoms of hormone hypersecretion associated with other types of NETs, they should be used with caution in patients with insulinoma. Somatostatin analogues may suppress counterregulatory hormones, such as growth hormone (GH), glucagon, and catechol­ amines, and precipitously worsen hypoglycemia. Diazoxide has histori­ cally been used in the initial management of patients with insulinoma and results in inhibition of insulin release, though it can also be associ­ ated with side effects including sodium retention and nausea. Evero­ limus, in addition to its antitumor effect (see below), is effective in improving glycemic control in patients with insulinoma. The benefits of everolimus in this setting may be related both to induction of insulin resistance and a direct antitumor effect. The use of anti-insulin recep­ tor monoclonal antibodies may be highly effective in treating the hypo­ glycemia associated with insulinoma, although currently their use for this indication remains investigational Insulinomas may be difficult to localize, as they are less consistently avid on somatostatin scintigraphy than other pancreatic NETs. Insulinomas are also generally small, with the majority measuring <2 cm in diameter. Because of their generally small size, insulinomas are best localized with endoscopic ultrasound (EUS). In the absence of metastatic disease, surgical resection is usu­ ally recommended. The primary treatment for exophytic or peripheral insulinomas is enucleation. If enucleation is not possible because of invasion or the location of the tumor within the pancreas, then pan­ creatoduodenectomy for tumors in the head of the pancreas or distal pancreatectomy with preservation of the spleen for smaller tumors not involving splenic vessels may be considered. ■ ■GLUCAGONOMA Patients with glucagonoma most commonly present with a charac­ teristic dermatitis, called necrolytic migratory erythema (Fig. 89-2). The rash usually involves intertriginous sites, especially in the groin or buttock, and can wax and wane. Other common presenting symptoms of glucagonoma include glucose intolerance and weight loss. The diag­ nosis of glucagonoma can be confirmed by demonstrating an increased plasma glucagon level, generally in excess of 1000 pg/mL. Somatostatin analogues are usually highly effective as an initial treatment to alleviate the symptoms and rash associated with glucagon hypersecretion. The majority of glucagonomas are large in size at presentation and arise in FIGURE 89-2  Glucagonoma syndrome. Patients with glucagonoma may present with a classic skin rash, necrolytic migratory erythema (shown). Other presenting symptoms include glucose intolerance and weight loss. the tail of the pancreas. For patients with localized disease, distal pan­ createctomy and splenectomy are recommended. A hypercoagulable state has been reported in up to 33% of patients with glucagonoma, and perioperative anticoagulation should generally be employed. ■ ■SOMATOSTATINOMA Patients with somatostatinoma typically present with diabetes mellitus, gallbladder disease, diarrhea, and steatorrhea. Somatostatinomas occur primarily in the pancreas or duodenum, are usually large, and are com­ monly metastatic at presentation. They are only rarely associated with MEN 1. The diagnosis of somatostatinoma is based on the demonstra­ tion of elevated plasma somatostatin levels, and as such, the potential benefits of using somatostatin analogues as a treatment for patients with somatostatinoma are questionable. Surgery is recommended for patients with localized disease. ■ ■VIPOMA VIPomas are associated with a distinct syndrome that has been variously called Verner-Morrison syndrome, pancreatic cholera, and WDHA syndrome (watery diarrhea, hypokalemia, and achlorhydria). VIP is a 28-amino-acid peptide that mimics the effects of the cholera toxin by stimulating chloride secretion in the small intestine and increasing smooth-muscle contractility, resulting in profound diarrhea. Treatment of dehydration, hypokalemia, and electrolyte losses with fluid and electrolyte replacement is the most critical initial treatment for patients with VIPoma. VIPomas are usually solitary and arise in the pancreatic tail. Elevated plasma levels of VIP are typical but should not be the only basis of the diagnosis of VIPomas because they can occur with some diarrheal states including inflammatory bowel disease, in the setting of small-bowel resection, and radiation enteritis. Chronic surreptitious use of laxatives/diuretics can be particularly difficult to detect clinically. Somatostatin analogues are usually highly effective in controlling the diarrhea; surgical resection is recommended for patients with localized disease. ■ ■OTHER SECRETORY PANCREATIC NETS Pancreatic NETs secreting GH-releasing factor (GRF), calcitonin, ACTH, and PTH-related protein have also been described; it is also possible for pancreatic NETs to secrete more than one hormone or for the secretory profiles to evolve over time. Gastrinomas, in particular, may evolve and may be associated with secretion of ACTH, resulting in ectopic Cushing’s syndrome. Tumors secreting these hormones may not be as responsive to treatment with somatostatin analogues as the more common pancreatic NETs and the associated hormonal symptoms may cause significant morbidity. As with other pancreatic NETs, patients with localized disease are generally treated with surgi­ cal resection. In patients with ACTH-secreting tumors, the associated symptoms of Cushing’s syndrome can be alleviated with the use of metyrapone, an agent that directly inhibits cortisol synthesis. Adrenal­ ectomy may also be considered if resection of the primary tumor is not possible or in the setting of metastatic disease. ■ ■PANCREATIC NETS ARISING IN THE SETTING OF MEN 1 Pancreatic NETs occurring in patients with MEN 1 are typically multiple and often pursue a relatively indolent course. Because of the high probability of multiple tumors, surgical resection of confirmed pancreatic NETs in patients with MEN 1 is usually undertaken with caution given the likelihood of tumors arising in the remaining pan­ creas if partial pancreatectomy is undertaken as well as the significant morbidities associated with total pancreatectomy. However, for symp­ tomatic tumors or for growing tumors >2 cm in size, surgical resection may still be considered. CHAPTER 89 ■ ■NONFUNCTIONING PANCREATIC NETS As noted above, the majority of pancreatic NETs are not associated with symptoms of hormone hypersecretion and are considered “non­ functional.” As a result, they often remain clinically silent and either are diagnosed incidentally or are not diagnosed until widespread, metastatic disease is present resulting in anatomic symptoms. If they are localized at diagnosis, the general treatment recommendation is surgical resection; however, the management of small, asymptomatic pancreatic NETs is debated. Assuming tumors are low grade, patients with incidentally discovered, low-grade tumors measuring <1 cm in size can generally be safely followed. However, some studies have sug­ gested that at least some tumors measuring <2 cm in size can pursue a more aggressive course and that surgical resection may be warranted in some cases. Management of small, incidentally discovered, asymptom­ atic, low-grade pancreatic NETs is therefore based on clinical judge­ ment, taking into account surgical risk and patient comorbidities. For tumors measuring >2 cm in diameter, metastases pose a significant risk and surgical resection is generally recommended in patients for whom surgery is not contraindicated. Gastrointestinal Neuroendocrine Tumors CLINICAL PRESENTATION AND MANAGEMENT OF LOCALIZED EXTRAPANCREATIC GASTROINTESTINAL NEUROENDOCRINE TUMORS Extrapancreatic GI NETs, historically called carcinoid tumors, may arise virtually anywhere in the GI tract and differ significantly in their clinical characteristics depending on their location. The most common locations for extrapancreatic NETs are the stomach, distal small intes­ tine, appendix, and rectum. ■ ■GASTRIC NETS Gastric NETs can be categorized into three groups: type 1 (associated with chronic atrophic gastritis); type 2 (associated with gastrinomas and ZES), and type 3 (sporadic, gastric NETs). Type 1 gastric NETs are the most common of the three types. In type 1 gastric NETs, chronic atrophic gastritis results in loss of acid secretion with consequent loss of the negative feedback loop on gastrin-producing cells in the antrum of the stomach. Pernicious anemia is also commonly associated with this condition; classic laboratory findings are a markedly elevated gastrin level and low levels of vitamin B12. Unchecked gastrin secretion in these patients results in hyperplasia of the endocrine cells in the gastric fundus. A typical finding on endoscopy is diffuse endocrine cell hyperplasia with multiple gastric carcinoid tumors (Fig. 89-3). These PART 4 Oncology and Hematology FIGURE 89-3  Multifocal gastric neuroendocrine tumor. (Courtesy of Christopher Huang, MD, Boston Medical Center.) tumors generally pursue a benign course and can be monitored with serial endoscopy. In cases where tumors continue to grow or become symptomatic, antrectomy to remove the source of gastrin production can result in tumor regression. Type 2 tumors are rare and usually occur in the setting of gastrinoma; as with type 1 gastric NETs, elevated gastrin levels result in diffuse gastric neuroendocrine hyperplasia and multifocal gastric NETs. Resection of the gastrinoma, removing the source of gastrin production, is the treatment of choice. In contrast to type 1 and type 2 gastric NETs, type 3 gastric NETs are generally solitary, arise in the setting of normal gastrin levels, and may pursue a far more aggressive course. For early-stage, smaller tumors, endoscopic or wedge resection may be performed. For larger tumors, partial gastrectomy with lymphadenectomy is recommended. ■ ■NETS OF THE SMALL INTESTINE Small-bowel NETs occur most commonly in the terminal ileum and are notoriously difficult to diagnose at an early stage. One reason for this is that they arise within the muscularis, and their submucosal location makes them difficult to see during routine colonoscopy (Fig. 89-4A). Small-bowel NETs are also often multifocal; multifocal tumors appear to arise independently throughout the small intestine, although the mechanisms underlying this phenomenon remain uncertain. A B FIGURE 89-4  Small intestine neuroendocrine tumor. A. Small intestine neuroendocrine tumors arising in submucosal location. The submucosal location of small intestine neuroendocrine tumors, together with their location beyond the ileocecal valve in the terminal ileum, can make endoscopic detection challenging. B. Classic “spoke and wheel” appearance of calcified mesenteric mass associated with small intestine primary neuroendocrine tumor. Mesenteric fibrosis commonly leads to intermittent obstructive symptoms and can also lead to ischemia when the mesenteric vasculature is involved. (Fig. B: Courtesy of Christina LeBedis, MD, Boston Medical Center.) Small-bowel NETs are often associated with desmoplasia and mes­ enteric fibrosis, likely as a result of fibroblast proliferation stimulated by tumor serotonin secretion. Mesenteric fibrosis frequently results in intermittent small-bowel obstruction and, in some cases, bowel ischemia due to involvement of the mesenteric vessels. Patients may experience symptoms of intermittent abdominal pain and associated diarrhea, sometimes for months or years before diagnosis, that because of the difficulty in diagnosis are often attributed to irritable bowel syn­ drome. One classic finding that can aid in diagnosis is that the lymph node metastases associated with small intestine NETs are usually larger than the primary tumor and may be calcified, which, together with the tethering of the small intestine caused by the associated fibrosis, results in a classic “spoke and wheel” appearance on CT (Fig. 89-4B). Surgical resection of the primary tumor and associated metastases is recommended when feasible and is performed with curative intent when distant metastatic disease is not already present. Resection should also be considered in patients with metastatic disease experi­ encing intermittent obstruction or abdominal discomfort thought to be related to the primary tumor or associated mesenteric disease. Some have also advocated the routine resection of asymptomatic small-bowel primary tumors in patients with distant metastatic disease, with the rationale that this may be a way to prevent the future development of fibrosis and obstruction and preempt the development of unresectable disease due to tumor involvement of the mesenteric vessels. However, the available data on the benefits of resecting an asymptomatic primary tumor in this context are conflicting. Some studies have suggested that this practice results in an overall survival benefit, but the retrospective nature of these studies makes the data difficult to interpret given the high potential for selection bias in patients taken to surgery compared with those who were not. Other studies have suggested that prophy­ lactic primary tumor resection confers no survival benefit and that surgery can be safely delayed until it is indicated based on the develop­ ment of symptoms. ■ ■NETS OF THE APPENDIX NETs are one of the most common tumors arising in the appendix. They are typically discovered incidentally in younger individuals undergoing appendectomy for acute appendicitis and not uncom­ monly are identified only at the time of pathology review. While the unexpected diagnosis of an appendiceal NET in such situations can cause considerable anxiety, in the majority of cases, the prognosis is excellent. Indeed, the clinical behavior of appendiceal NETs has been inferred from multiple large retrospective surgical series that suggest that the risk of lymph node or distant metastases from appendiceal NETs with well-differentiated histology and a tumor diameter measur­ ing <2 cm is extremely low. In such cases, appendectomy alone is felt to be a sufficient surgical procedure. In contrast, the risk of metastases for tumors measuring 2–3 cm is ~20–30% and is even greater for tumors measuring >3 cm. For patients with larger tumors, more formal staging studies with either cross-sectional imaging or somatostatin scintigraphy are generally recommended to assess for distant metastases, and a subsequent right colectomy to remove regional lymph nodes is performed if no distant metastases are observed. Whether right colectomy should be per­ formed for tumors measuring <2 cm with features such as mesoappen­ diceal invasion or tumor origin at the appendiceal base, which in some series have suggested a poorer prognosis, remains uncertain. Addi­ tionally, tumors may arise in which neuroendocrine cells are admixed with mucin-producing cells or cells exhibiting features of frank adeno­ carcinoma. In such mixed neuroendocrine-adenocarcinoma tumors, sometimes termed “adenocarcinoids,” treatment recommendations are generally dictated by the more aggressive component of the tumor and align with typical recommendations for colorectal adenocarcinoma. ■ ■RECTAL NETS With the increased use of screening colonoscopy, the diagnosis of rectal NET has also become more common. For unclear reasons, the incidence of rectal carcinoid tumors shows geographic variation. In European studies, they compose up to 14% of all NETs, while in some Asian series (Japan, China, Korea), they compose up to 90% of all NETs. The majority of rectal NETs are small, measuring <1 cm in diameter, and have well-differentiated histology. These tumors rarely metastasize and can usually be safely removed endoscopically with subsequent endoscopic monitoring. In contrast, up to one-third of rectal NETs between 1 and 2 cm are associated with metastases, and those >2 cm, though uncommon, metastasize in >70% of patients. When identified early, these tumors generally require a surgical resec­ tion. In contrast to NETs of the appendix and small intestine, hormone secretion from rectal NETs, even when metastatic, is exceedingly rare. CLINICAL PRESENTATION, DIAGNOSIS, AND EVALUATION OF PATIENTS WITH METASTATIC NEUROENDOCRINE TUMORS While patients who undergo resection of localized NETs may be at risk of developing tumor recurrence or metastatic disease, postoperative treatment has not yet been shown to alter the risk of recurrence, and systemic adjuvant therapy is not recommended following resection of well-differentiated NETs, as it is for some other cancers. Whether adju­ vant systemic therapy may be of benefit following resection of highgrade NETs is uncertain, and an approach utilizing platinum-based chemotherapy with or without external-beam radiation, analogous to that used in small-cell carcinoma, is sometimes considered. The evaluation of patients with known or suspected metastatic disease generally includes both standard cross-sectional imaging such as CT or MRI and somatostatin scintigraphy. Somatostatin scintig­ raphy in this setting is based on the fact that >90% of NETs express somatostatin receptors. Gallium-68 (68GA) dotatate, as well as 68GA DOTATOC and copper-64 dotatate, are all radioligands bound to a somatostatin analogue and can be used as a nuclear medicine tracer to perform positron emission tomography (PET) scanning that is highly sensitive in detecting both primary NETs and metastases (Fig. 89-5). Because of the sensitivity of these approaches, false-positive results can occur due to somatostatin receptor expression in other tissues. Physi­ ologic uptake in the pancreatic uncinated process is common; uptake can also occur in the setting of sarcoidosis, in meningiomas, and in thyroid goiter or thyroiditis. Standard fluorodeoxyglucose (FDG) PET scans are often negative in well-differentiated NET due to their low metabolic activity but can show uptake in higher-grade tumors; conversely, rates of somatostatin expression tend to be lower in highergrade tumors, and 68GA dotatate scans may be negative in this setting. The utility of blood-based tumor markers in NETs is controversial. The circulating tumor marker chromogranin A is commonly used as a screen for the presence of NETs and also to monitor for both recur­ rence and progression of disease in patients with known metastases. While chromogranin A is elevated in patients with metastatic NETs, it is neither particularly sensitive nor specific. A broad range of different assays for chromogranin A have also posed challenges in interpreting results in a standardized fashion. Chromogranin A is often elevated in a number of nonmalignant conditions, including in patients with CHAPTER 89 FIGURE 89-5  Gallium-68 dotatate positron emission tomography (PET) scan demonstrating a small-bowel neuroendocrine tumor and associated mesenteric mass. (Courtesy of Sara Meibom, MD, Boston Medical Center.) Gastrointestinal Neuroendocrine Tumors impaired renal function and in patients who are taking PPIs. Elevated values of chromogranin A should be interpreted with caution in patients in whom a NET is being considered but in whom a diagnosis has not been established. The overall survival durations for patients with metastatic NETs vary significantly, depending on both the primary location of the tumor and the histologic grade. Median survival durations for patients with well-differentiated NETs have markedly increased in recent years, likely reflecting both earlier diagnoses and improved treatments. For example, in early analyses of the SEER database, the median survival for patients with advanced pancreatic NETs was ~2 years; this had increased to 4 years in a more recent analysis. Similar increases were observed in patients with advanced small intestine NETs, where the median survival for patients with well-differentiated small intestine NETs exceeds 5 years. The sometimes prolonged survival of patients with NETs can make it challenging to determine at what point to initiate treatment. In patients with symptoms of hormone secretion, decisions to initiate therapy are straightforward. In asymptomatic patients, on the other hand, observation off treatment can sometimes be appropriate. Nevertheless, the natural course of NETs is ultimately to progress, and if treatment is not initiated, close monitoring is essen­ tial to ensure patients maximize access to available treatment options over the course of their disease. MANAGEMENT OF SYMPTOMS OF HORMONE HYPERSECRETION AND THE CARCINOID SYNDROME Patients with advanced NETs may in some cases experience more symptoms from hormone hypersecretion than from tumor bulk. The management of hormonal symptoms associated with pancreatic NETs depends on the hormone being secreted (see above). Patients with GI NETs, particularly those with small intestine or appendiceal primaries, may develop the carcinoid syndrome. Flushing and diarrhea are the two most common symptoms associated with carcinoid syndrome. The characteristic flush is of sudden onset; it is a deep red or violaceous erythema of the upper body, especially the neck and face, often associ­ ated with a feeling of warmth. Flushes may be precipitated by stress, alcohol, exercise, and certain foods such as cheese. Flushing episodes initially are brief, lasting 2–5 min, though later in the disease course, they may last hours. The diarrhea associated with carcinoid syndrome Carcinoid tumor Tryptophan Telotristat ethyl Tryptophan hydroxylase Hydroxytryptophan (5-HTP) Aromatic L-amino acid decarboxylase Serotonin (5-HT) 5-HT stored in secretory granules Secretion 5-HT in blood Monoamine oxidase Aldehyde dehydrogenase 5-Hydroxyindolacetic acid (5-HIAA) PART 4 Oncology and Hematology 5-HIAA filtered by kidney Excretion 5-HIAA in urine FIGURE 89-6  Serotonin synthesis and secretion in neuroendocrine tumors. Tryptophan is converted to hydroxytryptophan by tryptophan hydroxylase within the tumor cell and, subsequently, to serotonin (5-HT). Serotonin is subsequently converted to 5-hydroxyindole acetic acid (5-HIAA), which can be measured in a 24-h urine collection and can facilitate the diagnosis of carcinoid syndrome. Telotristat ethyl inhibits tryptophan hydroxylase and can be used as a treatment for carcinoid syndrome. may or may not be associated with flushing and is described as watery in nature. Diarrhea can be profound, sometimes occurring in excess of 10 times daily and is one of the symptoms that most significantly interferes with activities of daily living. Less common manifestations of the carcinoid syndrome include wheezing or asthma-like symptoms. Impaired cognitive function has also been described in particularly advanced cases. The main secretory product implicated in the carcinoid syndrome is serotonin (5-HT). Serotonin is synthesized from tryptophan by the enzyme tryptophan hydroxylase (Fig. 89-6). Up to 50% of dietary tryp­ tophan can be used in this synthetic pathway by tumor cells, resulting in inadequate supplies for conversion to niacin; hence, some patients develop symptoms of niacin deficiency and pellagra-like lesions. Serotonin has numerous biologic effects, including the stimulation of intestinal secretion, increasing intestinal motility, and the stimulation of fibroblast growth. Other secreted products contributing to carcinoid syndrome symptoms are thought to include histamines and tachyki­ nins, including substance P. ■ ■DIAGNOSIS AND TREATMENT OF THE CARCINOID SYNDROME While the carcinoid syndrome can develop in patients with NETs from almost any site, it is most commonly associated with appendiceal or small intestine NETs. In these patients, the syndrome usually develops only after the development of hepatic metastases or retroperitoneal lesions, allowing entry of serotonin and other vasoactive substances into the systemic circulation. While serotonin levels can be measured in plasma, such measurements are frequently highly variable. Evi­ dence of excess serotonin secretion can be more reliably confirmed by measuring levels of the serotonin metabolite 5-hydroxyindole acetic acid (5-HIAA), either in plasma or using a 24-h urine collection. Urine collections can be challenging, and false-positive elevations may occur if the patient is eating serotonin-rich foods (e.g., salmon, eggs). As a result, elevated levels of 5-HIAA are suggestive but not diagnostic of the carcinoid syndrome. Patients with NETs may also experience symptoms of carcinoid syndrome related to other secreted products, including histamine, absent evidence of serotonin secretion. Con­ versely, patients without NETs may also describe symptoms analogous to carcinoid syndrome but due to other causes. The symptoms associ­ ated with systemic mastocytosis, in particular, can be easily confused with carcinoid syndrome. The symptoms of carcinoid syndrome, including diarrhea, are generally refractory to standard antidiarrheals or other traditional medications but can often be well controlled with somatostatin analogues (Fig. 89-7). Somatostatin is a 14-amino-acid peptide that inhibits the secretion of a broad range of hormones. Due to its short half-life, administration of somatostatin itself is not therapeutically practical. Longer-acting somatostatin analogues, including octreotide and lanreotide, share an 8-amino-acid binding domain with naturally occurring somatostatin and bind primarily to somatostatin receptor subtypes 2 and 5. Both have been shown to be effective in the treatment of carcinoid syndrome. The presence of somatostatin receptors on NETs is predictive of response to somatostatin analogues and can be easily confirmed with uptake on somatostatin scintigraphy such as 68GA dotatate PET scan. Somatostatin analogue side effects are generally mild. Mild nausea, abdominal discomfort, bloating, and loose stools occur in up to onethird of patients during the first month or two of treatment but usually subsequently subside. Patients with persistent symptoms of bloating or loose stools may be experiencing pancreatic insufficiency associ­ ated with use of somatostatin analogues; use of pancreatic enzyme supplements can ameliorate these symptoms. Mild glucose intoler­ ance may also occur due to inhibition of insulin secretion. One of the more significant side effects associated with somatostatin analogues is impaired gallbladder contractility, resulting in delayed gallbladder emptying, and long-term administration of somatostatin analogues has been associated with an increased risk of cholelithiasis. For this reason, patients with advanced NETs in whom surgery is planned and for whom somatostatin analogue therapy is being considered should generally also undergo prophylactic cholecystectomy. Over time, for reasons that remain uncertain, patients receiving somatostatin analogues for symptoms of hormone secretion may become refractory to treatment. Not uncommonly, such patients experience symptom exacerbation toward the final week of each treat­ ment cycle. Such patients may benefit from an increased frequency of administration (i.e., every 3 weeks) or use of additional short-acting octreotide for breakthrough symptoms. The association between high levels of circulating serotonin and symptoms of the carcinoid syndrome has also led to efforts aiming to directly inhibit serotonin synthesis (Fig. 89-6). This approach was first undertaken in the late 1960s with the drug para-chlorophenylalanine, which was reported to reduce symptoms of carcinoid syndrome but also caused significant central nervous system (CNS) side effects. Telotristat ethyl, a tryptophan hydroxylase inhibitor with minimal CNS penetra­ tion, was evaluated in a randomized trial that enrolled 135 patients with persistent carcinoid syndrome–related diarrhea while receiving somatostatin analogues. Treatment with telotristat ethyl was associated with a reduction in bowel movement frequency as well as significant decreases in urinary 5-HIAA compared to placebo, consistent with its mechanism of directly inhibiting serotonin synthesis. Thus, telotristat is a treatment option for patients with carcinoid syndrome who have persistent diarrhea despite treatment with somatostatin analogues. ■ ■CARCINOID CRISIS Carcinoid crisis has been described in the setting of tumor manipula­ tion during surgery and, less commonly, after other interventions such as hepatic artery embolization or radionuclide therapy. It may also occur as a result of exogenous administration of epinephrine or during Gly Cys Ala s s Cys Thr Phe Ser Native somatostatin-14 D-Phe Cys Phe D-BNAL Cys D-Trp s s s s Lys Cys Thr Thr Cys Thr Octreotide Lanreotide FIGURE 89-7  Somatostatin analogues. Commonly used somatostatin analogues include octreotide and lanreotide, which mirror the molecular structure of human somatostatin and bind to somatostatin receptors on neuroendocrine tumors. Somatostatin analogues inhibit tumoral hormone secretion and also have an antiproliferative effect. Radiolabeled somatostatin analogues such as 177Lu-DOTA-octreotate, shown in the figure, share a similar molecular structure and are used therapeutically. induction of anesthesia. It is most common in patients who already have significant symptoms of carcinoid syndrome and is thought to be caused by a sudden release of biologically active compounds from the tumor. Carcinoid crisis can be life-threatening and can manifest as either profound hypotension or hypertension. Prospective studies on the prevention and management of carcinoid crisis are limited; how­ ever, somatostatin analogues should be readily available during surgical procedures, and in some cases, continuous prophylactic intravenous administration of somatostatin analogues has been utilized as a way to mitigate risk. ■ ■CARCINOID HEART DISEASE Carcinoid heart disease occurs in approximately two-thirds of patients with the carcinoid syndrome. Carcinoid heart lesions are characterized by plaque-like, fibrous endocardial thickening that classically involves the right side of the heart and often causes retraction and fixation of the leaflets of the tricuspid and pulmonary valves (Fig. 89-8). The fibrosis in carcinoid heart disease is thought to be directly related to exposure of heart valve fibroblasts to high circulating levels of serotonin. Lesions FIGURE 89-8  Carcinoid heart disease. Fibrosis secondary to elevated levels of circulating serotonin classically involves the tricuspid valve, resulting in valve retraction and tricuspid regurgitation. Asn Phe Lys Phe Trp Lys Thr D-Phe Cys Tyr HN HOOC Tyr O D-Trp N N s D-Trp 177Lu s Lys N N Lys Thr Cys Thr Val HOOC COOH 177Lu-DOTA-Tyr3-Octreotate CHAPTER 89 similar to those observed in carcinoid heart disease were observed in patients receiving fenfluramine, a drug also known to increase serotonin signaling, as well as in patients receiving ergot-containing dopamine receptor agonists for Parkinson’s disease. Metabolites of fenfluramine, as well as the dopamine receptor agonists, have high affinity for serotonin receptor subtype 5-HT2B receptors, whose activa­ tion is known to cause fibroblast mitogenesis and which are normally expressed in heart valve fibroblasts. These observations support the hypothesis that serotonin overproduction in patients with carcinoid syndrome mediates the valvular changes by activating 5-HT2B receptors in the endocardium. Gastrointestinal Neuroendocrine Tumors Tricuspid regurgitation is a nearly universal feature of carcinoid heart disease; tricuspid stenosis, pulmonary regurgitation, and pulmo­ nary stenosis may also occur. Left-sided heart disease occurs in <10% of patients and has been associated with the presence of a patent fora­ men ovale. The preponderance of lesions in the right heart is related directly to the fact that serotonin is secreted by liver metastases or retroperitoneal tumor deposits into the venous circulation and subse­ quently into the right atrium and right ventricle. The lower incidence of heart disease in the left heart is postulated to be due to the fact that serotonin is metabolized in the pulmonary vasculature before entering the left atrium and ventricle. Among patients with carcinoid syndrome, patients with heart disease exhibit higher levels of serum serotonin and urinary 5-HIAA excretion than patients without heart disease. Treat­ ment with somatostatin analogues resulting in decreased serotonin secretion does not result in regression of cardiac lesions. Reduction of serotonin levels as a result of treatment with somatostatin analogues or with the tryptophan hydroxylase inhibitor telotristat ethyl seems likely to slow progression of carcinoid heart disease but has not been formally evaluated in clinical trials. Right-sided heart failure in patients with carcinoid heart disease may lead to significant morbidity and mortality. The development of mul­ tiple new treatments to improve overall disease control in patients with advanced NETs has led to increased interest in valvular replacement, which may result in significant clinical benefit in appropriately selected patients with carcinoid heart disease. The appropriate timing of valve replace­ ment in such patients can be challenging given the competing desires to perform surgery before the onset of severe right-sided heart failure, which can increase surgical morbidity, and the need to achieve adequate overall tumor control. However, advanced and less invasive techniques, includ­ ing catheter-based valve replacement, have made valve replacement an increasingly attractive option for patients with this condition. HEPATIC-DIRECTED THERAPY FOR METASTATIC NETS The liver is one of the most common sites for metastases in patients with NETs and, in some cases, is the only site of metastatic disease. Hepatic-directed therapies can often be effective as a means of control­ ling, if not eliminating, metastases, particularly in patients who have more indolent tumors with well-differentiated histology. Common approaches for such patients include surgical resection, ablation or embolization, and orthotopic liver transplantation. For patients with limited hepatic disease whose tumors have welldifferentiated histology, surgical resection is generally considered the preferable option. While data are limited to retrospective series with the consequent risk of selection bias, long-term survival durations and symptomatic improvements reported in select populations of patients undergoing hepatic resection of neuroendocrine liver metastases compare favorably with outcomes associated with other management approaches, and 5-year survival rates approach 90% in some series. In patients in whom anatomy precludes resection or in whom a greater number of lesions are present, radiofrequency ablation or cryoabla­ tion can also be used, either as a primary treatment modality or as an adjunct to surgical resection. While ablation is considered to be less morbid than hepatic resection, it is generally utilized only in smaller tumors so that zones of ablation are limited. PART 4 Oncology and Hematology In most cases, however, liver metastases are large, multiple, and involve both lobes of the liver. In such cases, the benefit of surgical resection and ablation is limited. Hepatic arterial embolization can be considered in these cases, assuming that extrahepatic disease remains relatively limited and that clinical benefit can be achieved by reduc­ ing hepatic tumor bulk. Hepatic artery embolization is based on the principle that tumors in the liver derive most of their blood supply from the hepatic artery, whereas healthy hepatocytes derive most of their blood supply from the portal vein. Multiple different emboliza­ tion techniques have been explored, ranging from the simple infusion of gel foam powder into the hepatic artery (bland embolization) to the administration of chemotherapy or chemotherapy-eluting beads into the hepatic artery (chemoembolization) or the intra-arterial admin­ istration of radioisotope-tagged microspheres (radioembolization). Limited data suggest an optimal approach to embolization, and few studies have compared these approaches directly. Tumor response rates with all of these approaches generally exceed 50%. Specific approaches are therefore often tailored to the patient, taking into account tumor location, overall tumor burden, and comorbidities. Bland emboliza­ tion, for example, may be associated with less morbidity, whereas che­ moembolization or radioembolization may result in longer durations of response. The role of orthotopic liver transplantation for the treatment of NETs remains uncertain. Data from available institutional series sug­ gest that a small number of highly selected patients may achieve longterm survival. However, 5-year overall median survival durations in most series are ~50%, and the majority of patients undergoing hepatic transplantation develop tumor recurrence. Additionally, the wide­ spread utility of hepatic transplantation is limited by organ availability. Decisions regarding proceeding with transplantation in patients with advanced NETs are therefore highly individualized. SYSTEMIC TREATMENT TO CONTROL TUMOR GROWTH While hepatic-directed therapies can be effective in the management of patients with liver-predominant disease, a majority of patients will either present with or ultimately develop more widespread metastases. A number of systemic treatment options have been developed and can be effective in treating such patients. These options include treatment with traditional somatostatin analogues, peptide receptor radioligand therapy, traditional cytotoxic chemotherapy, and an increasing array of molecularly targeted therapies targeting the mTOR or vascular endo­ thelial growth factor (VEGF) pathways (Table 89-3). The choice and sequence of therapy depend in part on the type of tumor, the extent of disease, and patient symptoms and comorbidities. TABLE 89-3  Selected Randomized Trials of Therapeutic Agents for the Treatment of Advanced Neuroendocrine Tumors (NETs) NUMBER OF PATIENTS PROGRESSION-FREE SURVIVAL TUMOR TYPE Pancreatic and Extrapancreatic NETs Lanreotide vs placebo (CLARINET) 65% vs 33% at 2 years (p <.001) 177-Lutetium dotatate vs octreotide (NETTER 2) 226 (limited to histologic grade 2 and 3 tumors) 22.8 vs 8.5 months (p <.0001) Cabozantinib vs placebo (CABINET) 298 (203 extrapancreatic NETs [epNET] and 95 pancreatic NETs [pNET]) 8.5 vs 4 months (epNET); 13.8 vs 4.5 months (pNET) (p <.0001 for both cohorts) Pancreatic NET Everolimus vs placebo (RADIANT 3) 11 vs 4.6 months (p <.001) Sunitinib vs placebo 11.4 vs 5.5 months (p <.001) Surufatinib vs placebo 10.9 vs 3.7 months (p = .001) Temozolomide/ capecitabine vs temozolomide 22.7 vs 14.4 months (p = .021) Extrapancreatic NET Octreotide vs placebo (PROMID) 14.3 vs 6 monthsa Everolimus + octreotide vs octreotide (RADIANT 2) 16.4 vs 11.3 months Everolimus vs placebo (RADIANT 4) 11 vs 3.9 months Surufatinib vs placebo 9.2 vs 3.8 months (p <.0001) Pazopanib vs placebo 11.6 vs 8.5 months (p <.0005) 177-Lutetium dotatate vs octreotide (NETTER 1) 65.2 vs 10.8% at 20 months (p <.001) aTime to tumor progression. ■ ■SOMATOSTATIN ANALOGUES Somatostatin analogues were originally developed as a treatment to reduce hormone secretion in NETs but are also effective in slowing tumor growth. The biologic mechanisms underlying this effect remain uncertain, but clinical studies have been definitive. The first of these studies, the PROMID study, randomized patients with metastatic small-intestinal NET to receive either octreotide LAR at a dose of 30 mg monthly or placebo. The median time to tumor progression in patients receiving octreotide was 14 months compared to only 6 months for patients receiving placebo. Because the study was limited to patients with small-intestinal NET, the generalizability of these results to patients with NETs of other origins, including pancreatic NET, was initially uncertain. This question was ultimately addressed by the phase 3 CLARINET trial, which compared lanreotide, a soma­ tostatin analogue that is similar to octreotide in its somatostatin receptor–binding affinities, to placebo in 204 patients with a range of advanced well- or moderately differentiated gastroenteropancreatic NETs. Progression-free survival duration at 2 years was 65% in patients receiving lanreotide and 33% in patients receiving placebo, a difference that was statistically significant. One unusual aspect of the PROMID and CLARINET studies is the difference in progression-free survival durations in the placebo arms of the studies, which has been attributed to differences in patient selection. Either octreotide or lanreotide is currently considered an acceptable option for control of tumor growth in patients with advanced NETs. The timing of initiation of somatostatin analogues in patients with advanced NETs remains uncertain. The variable clinical course of NETs means that tumors can remain indolent for years even without treatment. For patients with asymptomatic, small-volume disease, observation alone may be an appropriate initial option. However, for patients with a larger disease burden, evidence of disease progression, or symptomatic disease, somatostatin analogues are generally used as an initial systemic treatment due to their ease of use and tolerability. ■ ■PEPTIDE RECEPTOR RADIOLIGAND THERAPY Peptide receptor radioligand therapy employs the systemic administra­ tion of radiolabeled somatostatin analogues and is a treatment option for patients who require more aggressive treatment due to progression on traditional somatostatin analogues or other therapies (Fig. 89-7). Peptide receptor radioligand therapy may also be considered as an initial treatment in patients with significant symptoms or tumor bur­ den. With this approach, a radioligand is coupled to a somatostatin analogue, using the somatostatin analogue to target the tumor. When bound to the tumor cell, the radioligand is then internalized, resulting in cell death. Due to its mechanism of action, peptide receptor radioli­ gand therapy is only considered in patients whose tumors demonstrate uptake on somatostatin scintigraphy. Several different radioligands have been evaluated, the most suc­ cessful of which have been yttrium (90Y) and lutetium (177Lu). These two ligands differ from one another in terms of their particle energy and tissue penetration; of the two, 90Y-DOTA-TOC emits higherenergy β particles and has deeper tissue penetration. 90Y-DOTA-TOC has been evaluated in numerous series with overall tumor responses reported in approximately one-third of patients. Enthusiasm for this approach, however, has been tempered due to concerns about side effects including both renal and hematologic toxicity. 177Lu-DOTA-octreotate emits both β particles and lower-energy γ particles and, in most studies, has been associated with less toxicity than 90Y-DOTA-TOC. Initial single-center studies with 177Lu-DOTAoctreotate showed promising antitumor activity, and based on these studies, a randomized trial of 177Lu-dotatate in midgut GI NETs was undertaken. In this study (NETTER-1), 229 patients with inoper­ able, somatostatin receptor–positive midgut NETs were randomly assigned to receive either four doses of 177Lu-dotatate administered intravenously every 8 weeks or treatment with high-dose octreotide LAR (60 mg) every 4 weeks. Treatment with 177Lu-dotatate was associ­ ated with objective tumor responses in 18% of patients and also was associated with a significant improvement in progression-free survival: progression-free survival at month 20 was 10.8% for octreotide LAR alone and 65.2% in the 177Lu-dotatate group. Subsequent analyses have also suggested improved overall survival associated with 177Lu-dotatate treatment, as well as improvements in quality of life across a number of parameters, including global health status, overall physical functioning, fatigue, pain, and diarrhea. One limitation of the NETTER-1 study was its restriction to patients with advanced small intestine NETs with low-grade histology. A subse­ quent study, NETTER-2, randomized 226 patients with a broader range of gastroenteropancreatic neuroendocrine tumors that were higher grade (grade 2 or 3) to receive treatment with 177Lu-dotatate or octreo­ tide alone. This study confirmed the activity of 177Lu-dotatate in this patient population; median progression-free survival was 22.8 months for patients receiving 177Lu-dotatate and 8.5 months for patients receiv­ ing octreotide alone. The renal clearance of radiopeptides, including 177Lu-DOTA-octreo­ tate, poses a risk of renal toxicity; this risk can be mitigated with the coadministration of intravenous amino acids during treatment. Longerterm safety data are available from large institutional series that include >1000 patients. Reported toxicities from these series have included rare cases of acute leukemia and myelodysplastic syndrome, presumably associated with radiation exposure. Nevertheless, these studies generally support both the efficacy and safety of 177Lu-dotatate as a treatment for patients with a range of somatostatin receptor–positive NETs. ■ ■ALKYLATING AGENTS While the efficacy of traditional cytotoxic chemotherapy appears to be minimal in most extrapancreatic GI NETs, alkylating agents have a clear role in the treatment of advanced pancreatic NETs. Streptozocinbased combination therapy was historically used as treatment standard in such patients but has largely fallen out of favor due to both toxicity concerns and a cumbersome administration schedule. Temozolomide is an orally administered alkylating agent that has largely replaced streptozocin as a backbone in combination regimens used for the treat­ ment of pancreatic NETs. Initial studies evaluating temozolomide in combination with a range of different agents showed that temozolomide-based combination ther­ apy was associated with tumor responses in 24–70% of patients. One of the most active combination regimens appeared to be temozolomide and capecitabine. This combination was subsequently compared to temozolomide alone in a prospective randomized study undertaken by the Eastern Cooperative Oncology Group (ECOG) that enrolled 144 patients with advanced pancreatic NETs. The overall response rates in the two arms were relatively similar; 33% of patients who received the combination of temozolomide and capecitabine experienced objective tumor responses as compared to 28% of the patients who received temozolomide as a single agent. However, progression-free survival was significantly longer in the combination arm (22.7 vs 14.4 months). Based on these results, the combination of temozolomide and capecitabine is now the preferred chemotherapy combination for advanced pancreatic NETs. The reason that some pancreatic NETs respond to alkylating agents while others do not is uncertain. In patients with glioblastoma, methyl­ ation of the promoter region for methylguanine DNA methyltransfer­ ase (MGMT) is associated with decreased MGMT protein expression and is highly associated with temozolomide responsiveness. MGMT is an enzyme that is responsible for repairing DNA damage induced by alkylating agents. Reduced levels of MGMT presumably impair the ability of tumor cells to repair their DNA in response to treatment and enhance the cytotoxicity of temozolomide. Several retrospective stud­ ies, as well as data from the prospective ECOG study, have suggested that lack of MGMT expression in pancreatic NET may be associated with responsiveness to temozolomide-based therapy, although findings have not been definitive. CHAPTER 89 Gastrointestinal Neuroendocrine Tumors SMALL-MOLECULE TYROSINE KINASE INHIBITORS The highly vascular nature of NETs combined with observations in preclinical models that disruption of signaling pathways associated with VEGF inhibits neuroendocrine cell growth prompted a number of clinical trials evaluating therapeutic agents that inhibit the VEGF pathway in both pancreatic and extrapancreatic NETs. The VEGF pathway is activated through the binding of VEGF to its cell surface receptor, which initiates an intracellular signaling cascade that pro­ motes angiogenesis as well as cell growth, proliferation, and survival. Clinical trials of VEGF pathway inhibitors in NETs have included a number of small-molecule tyrosine kinase inhibitors that, while they differ to some extent in specificity, all have in common the property targeting VEGFR2, the receptor isoform most strongly implicated in promoting angiogenesis. Sunitinib, a multitargeted tyrosine kinase inhibitor that inhibits a range of growth factor receptors including VEGFR2, was one of the first agents in this class found to have activity in pancreatic NETs. In an initial phase 2 trial, sunitinib was administered to 109 patients with either pancreatic or extrapancreatic NET. Of 61 patients with pancre­ atic NET enrolled in the study, 11 had evidence of an objective tumor response. Based on these observations, sunitinib was evaluated in an international, randomized trial in which continuous administration of sunitinib (37.5 mg daily) was compared with placebo in 171 patients with advanced, progressive pancreatic NET. The median progressionfree survival was significantly longer in patients treated with sunitinib compared with patients treated with placebo (11.4 vs 5.5 months). Common side effects associated with sunitinib included hypertension, proteinuria, and fatigue. A second VEGFR-targeted tyrosine kinase inhibitor, surufatinib, was evaluated in a randomized trial in which 264 patients with advanced pancreatic NETs from 21 centers in China were randomized to receive either surufatinib, administered at a dose of 300 mg daily, or placebo. Patients receiving surufatinib experienced a median progressionfree survival duration of 10.9 months, as compared to 3.7 months in patients receiving placebo, closely mirroring the results of the earlier sunitinib study. Cabozantinib, a tyrosine kinase inhibitor with activ­ ity against not only VEGFR but also c-MET and related growth factor receptors, was evaluated against placebo in a randomized trial led by the ALLIANCE cooperative group that included both pancreatic and extrapancreatic NETs. Among the 95 pancreatic NET patients in the study, median progression-free survival was 13.8 months for those receiving cabozantinib and 4.5 months for those receiving placebo. Other small-molecule tyrosine kinase inhibitors that have been evalu­ ated in smaller, single-arm studies and have shown activity in pancre­ atic NETs, include sorafenib, pazopanib, and axitinib. Small-molecule tyrosine kinase inhibitors targeting the VEGF path­ way have also been evaluated in patients with advanced nonpancreatic GI NET. In most of these studies, objective tumor response rates are lower than those seen in pancreatic NET, though many of these initial studies also revealed low rates of tumor progression and encouraging progression-free survival durations, suggesting that these agents had antitumor activity. Pazopanib was compared to placebo in a random­ ized study undertaken by the ALLIANCE cooperative group, which enrolled 171 patients with nonpancreatic NETs. Patients treated with pazopanib in this study had a superior progression-free survival com­ pared to those who received placebo (11.6 vs 8.5 months), a difference that was statistically significant. Surufatinib was used in a randomized study of 198 patients with extrapancreatic NETs; the median progres­ sion-free survival was 9.2 months in patients receiving surufatinib and 3.8 months in those receiving placebo. The strongest results to date have come from a randomized study of cabozantinib (see above) that included 205 patients with extrapancreatic GI NET. In this study, median progression-free survival was 8.5 months in the cabozantinib arm as compared with 4 months in the placebo arm. Taken together with the results in the pancreatic NET cohort (above), these results provide a strong rationale for considering cabozantinib as a treatment option for patients with both advanced pancreatic and nonpancreatic GI NET. PART 4 Oncology and Hematology ■ ■mTOR INHIBITORS mTOR is an intracellular protein kinase that has been implicated in the regulation of a number of processes regulating cell growth in both normal and malignant cells. It functions as a downstream component of the PI3-AKT-mTOR pathway. This pathway is negatively regulated by the tuberous sclerosis complex, comprising TSC1 and TSC2. An association between the development of pancreatic NETs and inherited mutations in TSC2 in patients with tuberous sclerosis complex was a contributing factor to initial interest in exploring mTOR inhibition as a therapeutic approach in this setting. Following initial evidence of antitumor activity associated with everolimus (10 mg daily) in an international, multicenter, phase 2 trial of 160 patients, everolimus monotherapy (10 mg daily) was compared with best supportive care alone in the RADIANT-3 trial that enrolled 410 patients with advanced progressing pancreatic NET. While overall objective responses were uncommon, treatment with everolimus was associated with a significant prolongation in median progression-free survival (11.0 vs 4.6 months) compared to placebo, supporting its use as a standard treatment to control tumor growth in patients with advanced pancreatic NET. Common toxicities associated with evero­ limus are generally mild and can include stomatitis and rash; a more severe but less common side effect is pneumonitis. Everolimus was also associated with promising activity in early phase 2 studies enrolling patients with extrapancreatic NET. The first large, randomized study evaluating everolimus was the RADIANT-2 trial; 429 patients with advanced GI NETs were randomly assigned to receive octreotide LAR (30 mg intramuscularly every 28 days) with or without everolimus (10 mg daily). Treatment with everolimus in this study was associated with an improvement in median progressionfree survival (16.4 vs 11.3 months), but the difference in this study was of only borderline statistical significance. A second study, the RADIANT-4 study, enrolled 302 patients with advanced NETs of either GI (excluding pancreatic) or lung origin, randomizing them to receive either everolimus or placebo. In this study, treatment with octreotide was not required. As in the RADIANT-3 study, objective tumor responses were uncommon; however, median progression-free survival in patients who received everolimus was significantly longer than in those who received placebo (11 vs 3.9 months). Based on the results of this study, everolimus is considered a standard treatment for control of tumor growth in extrapancreatic NETs. ■ ■OTHER SYSTEMIC TREATMENTS FOR CONTROL OF TUMOR GROWTH Interferon α has been used as a treatment for advanced NETs for sev­ eral decades. With the development of newer approaches, its routine use has diminished. The use of interferon α was based primarily on observations in large, retrospective series where low-dose interferon α was reported to both reduce symptoms of hormonal hypersecre­ tion and slow tumor progression. Interferon can be myelosuppres­ sive, requiring dose titration, and in some patients can induce both fatigue and depression. Antitumor activity has also been reported with oxaliplatin-based chemotherapy regimens. A combined analysis of two phase 2 trials examining oxaliplatin-fluoropyrimidine chemotherapy plus bevacizumab in advanced NET suggested antitumor activity for these regimens; the benefit appeared to be greatest in patients with intermediate-grade rather than low-grade tumors. Treatment with immune checkpoint inhibitors has been found to be effective across multiple cancer types. The role of immune check­ point inhibitors for the treatment of neuroendocrine tumors has not yet been clearly established and appears to depend at least in part on tumor grade. Immunohistochemical and transcriptomic profiling in well-differentiated neuroendocrine tumors has revealed only low levels of PD-1 and PD-L1 expression together with high levels of immuno­ suppressive gene expression in tumor-associated myeloid cells. The KEYNOTE-158 study investigated the efficacy of pembrolizumab, a monoclonal antibody targeting the checkpoint marker PD-1, in mul­ tiple cancers, including 107 patients with neuroendocrine tumors of various sites. The overall tumor response rate in the neuroendocrine tumor cohort was only 3.7%. Other immunotherapeutic approaches, including use of chimeric antigen receptor T cells for the treatment of neuroendocrine tumors, remain investigational. ■ ■SYSTEMIC THERAPY FOR HIGH-GRADE NEUROENDOCRINE CARCINOMA High-grade NETs are relatively uncommon and tend to pursue an aggressive clinical course. In contrast to well-differentiated neuroen­ docrine tumors, high-grade neuroendocrine carcinomas may, at least in some cases, be quite responsive to immunotherapeutic approaches. A basket trial evaluating a combination of the anti-CTLA-4 mono­ clonal antibody ipilimumab together with the anti-PD-1 monoclonal antibody nivolumab enrolled 32 patients with poorly differentiated nonpancreatic neuroendocrine tumors; the overall tumor response rate was 44% in this cohort. Apart from these more recent immune-based approaches, chemotherapy for advanced high-grade neuroendocrine carcinoma has historically followed a paradigm analogous to that used for small-cell carcinoma of the lung, with combinations of either cis­ platin or carboplatin administered together with etoposide generally considered the preferred first-line approach. One of the most impor­ tant elements in determining the optimal chemotherapeutic approach is assessing the Ki-67 proliferative index. A large retrospective series that evaluated 252 patients with high-grade neuroendocrine carci­ noma found that the activity of platinum-based therapy was greatest in patients who had a Ki-67 proliferative index of 55% or higher; in these patients, the overall tumor response rate was 42%. In contrast, the overall response rate in patients in whom the Ki-67 proliferative index was <55% was only 15%. Acknowledgment Dr. Robert Jensen contributed this chapter in previous editions and some material from his chapter is retained here. ■ ■FURTHER READING Caplin ME et al: Lanreotide in metastatic enteropancreatic neuroen­ docrine tumors. N Engl J Med 371:224, 2014. # 19 - 90 Renal Cell Carcinoma ### 90 Renal Cell Carcinoma Dasari A et al: Trends in the incidence, prevalence, and survival out­ comes for patients with neuroendocrine tumors in the United States. JAMA Oncol 3:1336, 2017. Kulke MH et al: Telotristat ethyl, a tryptophan hydroxylase inhibitor for the treatment of carcinoid syndrome. J Clin Oncol 35:14, 2017. Kunz PL et al: Randomized study of temozolomide or temozolomide and capecitabine in patients with advanced pancreatic neuroendo­ crine tumors (ECOG-ACRIN E2211). J Clin Oncol 41:1359, 2023. Patel SP et al: A phase II basket trial of dual anti-CTLA-4 and antiPD-1 blockade in rare tumors (DART SWOG 1609) in patients with nonpancreatic neuroendocrine tumors. Clin Cancer Res 26:2290, 2020. Raymond E et al: Sunitinib malate for the treatment of pancreatic neu­ roendocrine tumors. N Engl J Med 364:501, 2011. Rindi G et al: A common classification framework for neuroendocrine neoplasms: An International Agency for Research on Cancer (IARC) and World Health Organization (WHO) expert consensus proposal. Mod Pathol 31:1770, 2018. Scarpa A et al: Whole genome landscape of pancreatic neuroendo­ crine tumors. Nature 543:65, 2017. Strosberg J et al: Phase 3 trial of 177 Lu-dotatate for midgut neuroen­ docrine tumors. N Engl J Med 376:125, 2017. Xu Z et al: Epidemiologic trends of and factors associated with overall survival for patients with gastroenteropancreatic neuroendocrine tumors in the United States. JAMA Network Open 4:e2124750, 2021. Yao JC et al: Everolimus for advanced pancreatic neuroendocrine tumors. N Engl J Med 364:514, 2011. Robert J. Motzer, Martin H. Voss Renal Cell Carcinoma Renal cell carcinomas account for 90–95% of malignant neoplasms arising from the kidney. Notable features include frequent diagnosis without symptoms, resistance to cytotoxic agents, robust activity of angiogenesis-targeted agents, immune infiltration commonly render­ ing tumors susceptible to checkpoint-directed immunotherapy, and a variable clinical course for patients with metastatic disease, including anecdotal reports of spontaneous regression. Most of the remaining TABLE 90-1  Hereditary Renal Cell Tumors SYNDROME CHROMOSOME(S) GENE PROTEIN KIDNEY TUMOR TYPE ADDITIONAL CLINICAL FINDINGS von Hippel-Lindau syndrome 3p25 VHL von Hippel-Lindau protein Clear cell Hemangioblastoma of the retina and central nervous system; pheochromocytoma; pancreatic and renal cysts; neuroendocrine tumors Hereditary papillary RCC 7p31 MET MET Papillary Bilateral and multifocal kidney tumors Hereditary leiomyomatosis and RCC (HLRCC syndrome) 1q42 FH Fumarate hydratase FH-deficient/HLRCC syndrome– associated RCC Birt-Hogg-Dubé syndrome 17p11 FLCN Folliculin Chromophobe; clear cell; oncocytoma Tuberous sclerosis 9q34 16p13 TSC1 TSC2 Hamartin Tuberin BAP1 tumor predisposition syndrome 3p21 BAP1 BAP1 Mostly clear cell, but chromophobe and papillary have also been reported Abbreviations: ESC, eosinophilic solid and cystic; FH, fumarate hydratase; HLRCC; hereditary leiomyomatosis and RCC; RCC, renal cell carcinoma; TSC, tuberous sclerosis. 5–10% of malignant neoplasms arising from the kidney are transitional cell carcinomas (urothelial carcinomas) originating in the lining of the renal pelvis. See Chap. 91 for transitional cell carcinomas. ■ ■EPIDEMIOLOGY The incidence of cancers of the kidney and renal pelvis rose for three decades, reached a plateau of approximately 64,000 cases annually in the United States between 2012 and 2018, but has since increased to approximately 81,000 cases annually, resulting in close to 15,000 deaths per year. It is the seventh most common cancer overall in the United States, the sixth most common in males, and the ninth most common in females; the male-to-female ratio is 2:1. Although this malignancy may be diagnosed at any age, it is uncommon in those under 45 years, and incidence peaks between the ages of 55 and 75 years. Many factors have been investigated as possible contributing causes; associations include cigarette smoking, obesity, and hypertension. Risk is also increased for patients with polycystic kidney disease that has been complicated by chronic renal failure. Most cases of renal cell carcinoma (RCC) are sporadic, although familial forms have been reported (Table 90-1). One well-established example includes clear cell RCC arising in the context of von HippelLindau (VHL) syndrome, an autosomal dominant disorder. Genetic studies identified the VHL gene on the short arm of chromosome 3. Individuals with VHL syndrome have a 70% estimated lifetime risk of developing clear cell RCC. Other VHL-associated neoplasms include retinal hemangioma, hemangioblastoma of the spinal cord and cerebel­ lum, pheochromocytoma, and neuroendocrine tumors. Belzutifan, an oral inhibitor of hypoxia-inducible factor (HIF-2α), is approved for treatment of VHL-associated cancers. Birt-Hogg-Dubé syndrome is a rare human autosomal dominant genetic disorder characterized by fibrofolliculomas (benign tumors arising in hair follicles), pulmonary cysts, and RCCs of varying histologies, most commonly the chromo­ phobe type, occurring in about a third of patients. This disorder is associated with mutations in the FLCN gene, which codes for folliculin. Other hereditary syndromes are summarized in Table 90-1. CHAPTER 90 Renal Cell Carcinoma ■ ■PATHOLOGY AND GENETICS Renal cell malignancies represent a heterogeneous group of tumors with distinct histopathologic, genetic, and clinical features (Table 90-2). Categories include clear cell carcinoma (70% of cases), papillary RCC (10–15%), chromophobe RCC (≤5%), molecularly defined entities such as TFE3-rearranged RCC (<5%), and other less common vari­ ants. Papillary tumors can be bilateral and multifocal. Chromophobe tumors tend to have a more indolent clinical course. TFE3-rearranged RCC, rare in adult patients, is the predominant histology in chil­ dren. SMARCB1-deficient RCC, previously called renal medullary Leiomyoma; uterine leiomyoma/ leiomyosarcoma Facial fibrofolliculoma; pulmonary cysts Angiomyolipomas; TSC-associated lymphangioleiomyomatosis; rare RCC with variety of histologic appearances including eosinophilic solid and cystic (ESC) RCC Angiofibroma, subungual fibroma; cardiac rhabdomyoma; adenomatous small intestine polyps; pulmonary and renal cysts; cortical tuber; subependymal giant cell astrocytomas Atypical Spitz tumors; uveal melanoma; cutaneous melanoma; basal cell carcinoma; malignant mesothelioma TABLE 90-2  Classification of Malignant Epithelial Neoplasms Arising from the Kidney CARCINOMA TYPE CHARACTERISTIC GROWTH PATTERN CHROMOSOMAL EVENTS Clear cell Varying growth patterns, including acinar, solid and sarcomatoid Papillary Papillary or sarcomatoid +7, +17, 9p– MET, CDKN2A (focal deletions) Chromophobe Solid, tubular, or sarcomatoid Whole arm losses (1, 2, 6, 10, 13, 17, and 21) TFE3-rarranged and TFEB-altered renal cell carcinomas Mimicking clear cell and papillary variants Xp11.2 translocations; t(6;11) translocations SMARCB1-deficient renal medullary carcinoma Varying growth patterns, including cribriform, reticular, sarcomatoid, adenoid, and microcystic carcinoma, is rare, very aggressive, and associated with sickle cell trait. Tumors that do not meet criteria for defined variants are generally referred to as “unclassified” with variable clinical courses. Clear cell tumors, the predominant histology, are found in >80% of patients who develop metastases and arise from the epithelial cells of the proximal tubules. Loss of chromosome 3p is uniformly seen as the earliest event in the development of these cancers. This leads to loss of heterozygosity for a number of relevant 3p genes, including VHL, PBRM1, BAP1, and SETD2, which can be functionally silenced through secondary events in the remaining allele. VHL encodes a tumor-suppressor protein that is involved in regulating the transcrip­ tion of vascular endothelial growth factor (VEGF) and a number of other effectors through ubiquitination of hypoxia-inducible factors (HIF). Inactivation of VHL, through upregulation of VEGF signaling, promotes tumor angiogenesis and growth, ultimately rendering clear cell RCC cells susceptible to antiangiogenesis therapy. PART 4 Oncology and Hematology Large-scale sequencing efforts have helped elucidate recurrent patterns of genomic evolution that correlate with distinct clinical phenotypes, e.g., varying levels of aggressiveness or specific patterns of metastatic spread. For example, early loss of chromosome 9p appears to confer a high risk for early metastatic dissemination and correlates with poor cancer-specific survival. A growing number of other RCC variants are well defined (see Table 90-2 for examples) yet can further vary by molecular features. For instance, up to 15% of RCCs are of the papillary subtype, and variant features can be distinguished by light microscopy but also molecular assays. Activating mutations in the MET oncogene or gain of chromo­ some 7 (where MET is located) are hallmark events of certain papil­ lary variants and considered actionable via targeted MET inhibitors. Tumors of the less common chromophobe subtype originate from the distal nephron. They are typically characterized by aneuploidy with common loss of an entire chromosome copy for chromosomes 1, 2, 6, 10, 13, and 17. ■ ■CLINICAL PRESENTATION Presenting signs and symptoms may include hematuria, flank or abdominal pain, and a palpable mass. Other symptoms are fever, weight loss, anemia, and a varicocele. Tumors are, however, commonly detected as an incidental finding on a radiograph. Widespread use of radiologic cross-sectional imaging (computed tomography [CT], magnetic resonance imaging [MRI]) contributes to earlier detection of renal masses during evaluation for other medical conditions. The increasing number of incidentally discovered low-stage tumors has contributed to an improved 5-year survival for patients with RCC and increased use of nephron-sparing surgery (partial nephrectomy). A spectrum of paraneoplastic syndromes has been associated with these malignancies, including erythrocytosis, hypercalcemia, nonmetastatic hepatic dysfunction (Stauffer’s syndrome), and acquired dysfibrino­ genemia. Erythrocytosis is noted at presentation in only about 3% of patients. Anemia, commonly a sign of more advanced disease, is more common. Kidney cancer was called the “internist’s tumor” since it was often discovered from the initial presentation of a paraneoplastic GENES WITH RECURRENT SOMATIC ALTERATIONS 3p–, 5q+, 14q–, 9p– VHL, PBRM1, BAP1, SETD2 TP53, PTEN, TERT promotor TFE3 gene fusions, TFEB gene fusions +8q, 22q–, 22q translocations SMARCB1 (focal deletions, mutations, gene fusions), SETD2 syndrome. This was more common before the era of modern imaging, as was initial presentation by the classic triad of hematuria, flank pain, and a palpable abdominal mass. The standard evaluation of patients with suspected renal tumors includes a CT scan of the abdomen and pelvis, chest radiograph, and urine analysis. If metastatic disease is suspected from the chest radio­ graph, a CT of the chest is warranted. MRI is useful in evaluating the inferior vena cava in cases of suspected tumor involvement or invasion by thrombus, or when intravenous contrast administration given with CT is prohibited by impaired renal function. In clinical practice, any solid renal masses should be considered malignant until proven otherwise; a definitive diagnosis is required. If no metastases are dem­ onstrated, surgery is indicated, even if the renal vein or inferior vena cava is invaded. In small tumors (particularly those of clear cell variant), the risk of impending metastatic spread is lower and surgery can poten­ tially be delayed. In that setting, a needle biopsy should be performed to confirm the underlying histology, and radiographic surveillance is indicated until the time of surgery. The differential diagnosis of a renal mass includes cysts, benign neoplasms (adenoma, angiomyolipoma, oncocytoma), inflammatory lesions (pyelonephritis or abscesses), and other malignancies originating in the kidney such as transitional cell carcinoma of the renal pelvis, sarcoma, lymphoma, and Wilms’ tumor or metastases from cancers originating in other organs. All of these are less common causes of renal masses than is RCC. The most common sites of distant metastases are the lungs, lymph nodes, liver, bone, and brain. These tumors may follow an unpredictable and protracted clini­ cal course. ■ ■STAGING AND PROGNOSIS Staging is based on the American Joint Committee on Cancer (AJCC) staging system (Fig. 90-1). Stage I tumors are ≤7 cm in greatest diameter and confined to the kidney; stage II tumors are >7 cm and confined to the kidney; stage III tumors extend through the renal capsule but are confined to Gerota’s fascia, grossly infiltrate the renal vein, or involve regional lymph nodes (N1); and stage IV disease includes tumors that have invaded adjacent organs or involve nonregional lymph nodes or distant metastases. Sixty-five percent of patients present with stage I or II disease, 15–20% with stage III, and 15–20% with stage IV. The 5-year survival rate is currently 77% across all RCCs but varies greatly by stage. Prognostic risk models are helpful for counseling patients diagnosed with metastatic disease and for anticipating survival rates when design­ ing a clinical trial. A widely used prognostic model for advanced dis­ ease, the International Metastatic RCC Database Consortium (IMDC) risk model, incorporates six factors shown to correlate with worse sur­ vival: poor performance status, low hemoglobin concentration, high serum calcium, high neutrophil levels, high platelet levels, and <1-year interval from diagnosis to systemic treatment. Patients with zero risk factors achieve significantly longer median survival (≥5 years) than patients with one or two risk factors (~4 years) and those with three to six risk factors (~3 years) when treated with first-line checkpoint inhibitor–containing combination regimens (see below). T1 T2 Involvement TNM TX Primary not involved T1 T1a T1b ≤7 cm ≤4 cm >4 cm T2 T2a T2b >7 cm to ≤10 cm >7 cm >10 cm T3 into major veins or perinephric tissues T3a in renal vein, renal sinus fat, or pelvicalyceal system T3b T3c into vena cava into vena cava T3 T4 T4 invasion beyond Gerota’s fascia Regional NX Regional lymph nodes not assessed N0 No regional lymph node involvement N1 Regional lymph node involvement Distant Metastases M0 M1 No distant metastases Distant metastases, including nonregional lymph nodes FIGURE 90-1  Renal cell carcinoma staging. TNM, tumor-node-metastasis. TREATMENT Renal Cell Carcinoma LOCALIZED TUMOR The standard management for stage I or II tumors and selected cases of stage III disease is radical or partial nephrectomy. A radical nephrectomy involves en bloc removal of Gerota’s fascia and its con­ tents, including the kidney, and commonly the ipsilateral adrenal gland and regional lymph nodes that appear abnormal on imaging or intraoperatively. Open, laparoscopic, or robotic surgical tech­ niques may be used. The role of a template lymphadenectomy in patients without apparent lymphadenopathy is controversial. Exten­ sion into the renal vein or inferior vena cava (stage III disease) does not preclude resection, which would then include thrombectomy. Nephron-sparing approaches, i.e., open or laparoscopic partial nephrectomy, may be appropriate depending on the size and loca­ tion of the tumor. This approach is particularly relevant for patients with solitary kidneys, bilateral tumors, or chronic renal insuf­ ficiency but can also be applied electively to resect small masses for patients with normal kidney function. Radical nephrectomy carries a greater risk for chronic kidney disease and cardiovascular morbidity and mortality. Adjuvant systemic therapies, including cytokines and targeted agents, have been studied in randomized clinical trials, largely with negative results. The checkpoint inhibitor pembrolizumab is approved in patients with increased risk of recurrence following nephrectomy, where 12 months of therapy was shown to improve disease-free survival compared to placebo. For those with low risk of recurrence, the standard of care remains active surveillance after nephrectomy. METASTATIC DISEASE Surgery has a limited role for patients with metastatic disease. Long-term survival may occur in patients who relapse with a soli­ tary site that is removed (metastasectomy). Nephrectomy despite presence of metastases (cytoreductive nephrectomy) is considered for carefully selected patients with stage IV disease. One indica­ tion for this approach can be to alleviate pain or hemorrhage of a primary tumor. Radiation therapy is used for palliation of bone or brain metas­ tases. The type of radiotherapy most commonly used is externalbeam therapy, including stereotactic radiosurgery and other forms of image-guided radiotherapy. Extent of Disease Anatomic Stage/Prognostic Groups I N0 M0 T1 II N0 M0 T2 III N0 or N1 N1 M0 M0 T3 T1 or T2, limited to kidney IV Any N Any N M0 M1 T4 Any T limited to kidney not beyond Gerota’s fascia not beyond Gerota’s fascia below diaphragm above diaphragm including contiguous extensions & into ipsilateral adrenal gland CHAPTER 90 Systemic therapy is the mainstay of care for metastatic disease. The timing of initiating such treatment should be carefully con­ sidered; some patients are asymptomatic at diagnosis, and with indolent behavior, it may be best to document progression before initiating treatment. Renal Cell Carcinoma Metastatic RCC is refractory to cytotoxic chemotherapy. Patients are treated with molecularly targeted agents, including targeted immunotherapies, i.e., checkpoint inhibitors. Treatments are con­ tinued with noncurative intent while tolerated and until disease progression is evident on cross-sectional imaging. Outcomes for patients with metastatic disease improved when increased under­ standing of underlying biology led to the successful development of several tyrosine kinase inhibitors (TKIs) targeting proangio­ genic signaling through the VEGF receptors as well as allosteric inhibitors of mammalian target of rapamycin (mTOR) signaling. Serial large-scale randomized trials demonstrated that such agents, typically orally available, could be administered sequentially and in combination. Pivotal studies, by design, defined a dedicated space for each regimen in treatment-naïve or pretreated patients (Table 90-3). Targeted immunotherapies were introduced after VEGF- and mTOR-directed agents had established standards of care in the first- and second-line setting. Nivolumab, a checkpoint inhibitor targeting PD-1, demonstrated superior overall survival compared to the mTOR inhibitor everolimus in a randomized trial in patients who had progressed on prior TKI therapy, challenging the standard approach in pretreated patients and positioning nivolumab as the new second-line agent of choice. Subsequently, immunotherapy combination regimens demonstrated efficacy in randomized trials conducted in treatment-naïve patients. In separate studies, four doublets demonstrated survival benefit over standard sunitinib therapy and changed the standard of care for untreated metastatic clear cell RCC toward two-drug, immunotherapy-containing regi­ mens: nivolumab in combination with the CTLA-4–directed check­ point inhibitor ipilimumab; the TKI axitinib together with the PD-1 inhibitor pembrolizumab; the TKI cabozantinib plus nivolumab; and the TKI lenvatinib paired with pembrolizumab. These combi­ nations demonstrated objective radiographic responses in 40–70% of patients, and complete radiographic disappearance of cancer is achieved in about 10% of patients. The majority of such anticancer effects were reported to be long-lasting. With an ever-growing number of approved options directed toward different molecular targets, biomarkers are urgently needed to help individualize therapeutic choices and to gain insight as to # 20 - 91 Cancer of the Bladder and Urinary Tract ### 91 Cancer of the Bladder and Urinary Tract TABLE 90-3  Commonly Used Systemic Regimens for Metastatic Renal Cell Carcinoma CLASS DRUG Antiangiogenic: TKIs Sunitinib Advanced RCC, first line Pazopanib Advanced RCC, first line Axitinib Advanced RCC, pretreated Cabozantinib Tivozanib Advanced RCC, pretreated with two or more prior systemic therapies Immunotherapy: checkpoint inhibitor Nivolumab Advanced RCC, pretreated with antiangiogenic therapy Combination therapies   TKI + mTOR inhibitor Lenvatinib + everolimus Advanced RCC, pretreated with one antiangiogenic therapy   PD-1 inhibitor + CTLA-4 inhibitor Nivolumab + ipilimumab Advanced intermediate-risk or poor-risk RCC, first line   PD-1 inhibitor + TKI Pembrolizumab + axitinib Advanced RCC, first line Nivolumab + cabozantinib Advanced RCC, first line Pembrolizumab + lenvatinib Advanced RCC, first line Abbreviations: CTLA-4, cytotoxic T lymphocyte-associated protein; FDA, U.S. Food and Drug Administration; mTOR, mammalian target of rapamycin; PD-1, programmed cell death-1; RCC, renal cell carcinoma; TKI, tyrosine kinase inhibitor. PART 4 Oncology and Hematology whether and why treatments are working. Although a multitude of candidate biomarkers have been investigated for their predictive value in metastatic RCC, none have been validated for clinical use to date. Projected overall survival in patients starting systemic therapies for newly diagnosed metastatic disease has tripled over the past 15–20 years; this can largely be attributed to the successful drug developments discussed here. ■ ■GLOBAL CONSIDERATIONS Worldwide, >400,000 patients are diagnosed each year with malignant tumors arising from the kidney, resulting in >175,000 deaths annu­ ally. Kidney cancer is the sixth most common cancer in men and the 10th most common cancer in women. Higher incidence is observed in developed countries, including the United States, Canada, Europe, Australia, New Zealand, and Uruguay. Lower rates are reported in Southeast Asia and Africa, though it is speculated that these rates may be underreported due to lack of disease-reporting structure and reduced access to diagnostic facilities. The incidence of kidney cancer has been steadily increasing over the past four decades. Mortality trends have stabilized in Europe and the United States, but not in less developed countries. This is likely related to differences in access to optimal therapies. Treatment guidelines for both localized and meta­ static renal cancer are similar between U.S. and European documents and contingent on the access to adequate health care and availability of targeted drugs to treat metastases. ■ ■FURTHER READING Choueiri TK et al: Adjuvant pembrolizumab after nephrectomy in renal-cell carcinoma. N Engl J Med 385:683, 2021. Choueiri TK et al: Nivolumab plus cabozantinib versus sunitinib for advanced renal-cell carcinoma. N Engl J Med 384:829, 2021. Huang J et al: A global trend analysis of kidney cancer incidence and mortality and their associations with smoking, alcohol consumption, and metabolic syndrome. Eur Urol Focus 8:200, 2022. Jonasch E et al: Belzutifan for renal cell carcinoma in von Hippel– Lindau Disease. N Engl J Med 385:2036, 2021. Moch H et al: The 2022 WHO classification of tumours of the urinary system and male genital organs—Part A: renal, penile, and testicular tumours. Eur Urol 82:458, 2022. Motzer RJ et al: Molecular subsets in renal cancer determine outcome to checkpoint and angiogenesis blockade. Cancer Cell 38:803, 2020. Motzer RJ et al: Nivolumab plus ipilimumab versus sunitinib in advanced renal-cell carcinoma. N Engl J Med 378:1277, 2018. FIRST FDA APPROVAL FOR RCC CURRENTLY USED FOR Advanced RCC, pretreated with antiangiogenic therapy Advanced RCC, first line Noah M. Hahn Cancer of the Bladder and Urinary Tract GLOBAL CONSIDERATIONS Within the United States, urothelial carcinomas of the bladder and urinary tract are most closely related to tobacco smoking history. However, within developing countries, water supplies contaminated with arsenic or schistosomiasis parasites also are major carcinogenic contributors. INTRODUCTION Cancers of the urinary tract including the bladder, renal pelvis, ureter, and urethra occur frequently, and they represent the second most com­ mon class of genitourinary cancers. Bladder cancer alone represents the sixth most common cancer diagnosis annually in the United States with 82,290 new cases and 16,710 deaths every year. Because cancers of the renal pelvis are often lumped in with all kidney cancers, the true incidence and mortality from nonbladder urinary tract cancers are less precise. While less frequent than bladder cancer, an additional 20,000 new cases and 5000 deaths are estimated every year. An accelerated understanding of the molecular underpinnings of bladder and uri­ nary tract cancer biology has led to a significant increase in urothelial cancer clinical trials resulting in U.S. Food and Drug Administration (FDA) approval of multiple new therapeutic agents since 2016 with more expected to follow. This chapter reviews the established, current, and emerging evidence that serves as the basis for the rapidly evolving standards of care for patients with bladder and urinary tract cancers. ■ ■CLINICAL EPIDEMIOLOGY AND RISK FACTORS Bladder cancer typically affects older patients with a median age at diagnosis of 73 years. Males are four times more frequently affected than females. Similarly, bladder cancer is more common in Caucasians than in Asian patients. Inheritable germline genetic risk factors have been observed in up to one-seventh of patients with bladder or urinary tract cancers. However, a predominant, singular germline genetic alter­ ation has not been identified. Patients with defects in mismatch repair genes leading to microsatellite instability (MLH1, MSH2, MSH6, etc.) as part of the familial cancer Lynch syndrome are at particular risk of upper urinary tract cancers of the renal pelvis and ureter. Additionally, patients with Cowden disease (PTEN mutations) or retinoblastoma (RB1 mutations) are at increased risk for developing bladder cancer. Historically, associations have existed between environmental toxic exposures and higher rates of developing bladder cancer. The aromatic amines benzidine and β-naphthylamine that can be present in indus­ trial dyes as well as arsenic that can be found in drinking water supplies in underdeveloped countries have been associated with increased blad­ der cancer risk. Other chemicals in the leather, paint, rubber, textiles, and printing industries have been associated with bladder cancer. Associations with exposures to hair dyes and hair sprays in workers in the hairstyling field have been suggested. Additionally, concern has been raised regarding use of the antidiabetic medication, pioglitazone, and bladder cancer risk. Extensive reviews and meta-analyses have produced differing conclusions. The data suggest a small risk of blad­ der cancer from long-term pioglitazone use, which has led to inclusion of bladder cancer risk within the pioglitazone prescribing information. An association between chronic inflammatory states and the develop­ ment of squamous bladder cancer clearly exists in underdeveloped countries in patients chronically infected with the parasitic disease schistosomiasis and in paraplegic patients with chronic indwelling catheters. Above and beyond each of these associations, however, smoking of tobacco products (cigarettes, cigars, pipes, etc.) remains the overwhelming leading risk factor for development of bladder cancer. Among new bladder cancer diagnoses, 90% of cases occur in current or former smokers. Toxicologists have estimated that >70 confirmed car­ cinogenic toxins are present within tobacco smoke. It is estimated that one-third of bladder cancer cases could be prevented through simple modification of lifestyle choices, in particular cessation of smoking. ■ ■CLINICAL PRESENTATION AND DIAGNOSTIC WORKUP Occasionally, patients will present with flank pain in association with an upper tract renal pelvis or ureter cancer or due to hydronephrosis in association with a bladder tumor obstructing the orifice of the ureter within the bladder. Only in rare cases do patients present with sig­ nificant cachexia and widespread metastatic disease. For most patients, painless hematuria (either gross or microscopic) represents the ini­ tial manifestation of an underlying urinary tract cancer. In females, hematuria due to malignancy can often be mistaken for a urinary tract infection or menstrual bleeding. While treatment with antibiotics is warranted if a concurrent urinary tract infection is noted on initial urinalysis, persistent hematuria requires further workup. Painless hematuria in males is almost always abnormal and should be worked up. Initial investigations in patients of either sex should include urine cytology and visual examination of the bladder by cystoscopy. Cytology is successful in identifying cancer in only 50% of individuals with highgrade bladder cancers. In addition to urine cytology, radiographic eval­ uation of the kidneys and upper urinary tract by CT urogram should be performed. A magnetic resonance (MR) urogram may be substituted in patients with poor renal function. Additional diagnostic testing of the urine to assess for cancer-associated chromosomal changes by fluorescent in situ hybridization, increased levels of nuclear mitotic proteins, increased bladder tumor–associated antigens, or higher levels of staining on cells shed by the bladder may identify some cancers missed by traditional cytology testing. However, they may also produce abnormal results in patients who do not have cancer. For now, these adjunct molecular tests are primarily utilized in detecting recurrent cancer in patients with a prior diagnosis of urinary tract cancer. Small tumors, particularly flat noninvasive tumors of the bladder, may be detected at higher rates with the use of blue light cystoscopy or narrowband imaging cystoscopy. Both blue light and narrow-band imaging cystoscopies are now used routinely in the monitoring of patients with bladder cancer. For patients with no bladder abnormalities in whom upper tract tumors are suspected, visualization of the upper urinary tracts and renal pelvises should be performed by ureteroscopy or ret­ rograde pyelography. In all patients with abnormalities noted in the bladder or upper urinary tracts, complete endoscopic resection for histologic diagnosis and staging should be performed when possible via either transurethral resection of bladder tumor (TURBT) or endoscopic resection of upper tract tumors. All metastatic patients should have genomic sequencing performed on their tumor tissue, circulating tumor DNA (ctDNA), or both. The role of genomic sequencing in earlier stages of disease is evolving. ■ ■HISTOLOGY Urothelial carcinoma, often called transitional cell carcinoma in the past, is the most common urinary tract cancer histology and is observed in ~90% of cases. Squamous, glandular, micropapillary, plas­ macytoid, sarcomatoid, and other variant features can often be found in portions of urothelial carcinoma tumors; however, pure variant histologies are rare. The presence of some variant histologies includ­ ing micropapillary and plasmacytoid has been associated with worse surgical outcomes compared to urothelial carcinoma. Nonurothelial variant histologies including squamous cell carcinoma, adenocarci­ noma, small-cell carcinoma, and carcinosarcoma collectively account for ≤10% of urinary tract tumors. Examples of traditional urothelial carcinoma and some of the variant histologies are shown in Fig. 91-1. ■ ■MOLECULAR BIOLOGY Clinically, urothelial carcinoma of the bladder displays a biphasic phe­ notype characterized by (1) low-grade papillary tumors that frequently recur but rarely invade or metastasize and (2) high-grade sometimes flat tumors that invade early leading to lethal metastatic disease. In both of these phenotypes, loss of portions of chromosomes 9q and 9p by loss of heterozygosity is an early molecular event, whose exact significance is not clear. Potential candidate regulatory genes in these genomic regions include CDNK2A, a cyclin-dependent kinase inhibi­ tor, and TSC1, a gene encoding hamartin mutated in tuberous sclerosis. Genomic investigations have demonstrated that low-grade tumors are characterized by alterations in the RAS/RAF signaling pathway with activating FGFR3 mutations or gene fusions present in 60–80% of patients. In contrast, the high-grade invasive phenotype is notable for early deleterious mutations in TP53 and RB1, alterations in CDH1 (E-cadherin), and increased expression of VEGFR2. In urothelial car­ cinoma of the renal pelvis and ureter, 10–20% of cases may be associ­ ated with Lynch syndrome hereditary defects in the MLH1, MSH2, or MSH6 mismatch repair genes, leading to microsatellite instability and frequent DNA mutations. Testing for germline mutations in these genes is recommended in patients with upper urinary tract urothelial carcinoma under the age of 60 at diagnosis, with a first-degree relative with a Lynch syndrome–associated cancer diagnosed under the age of 50, or with two first-degree relatives with a Lynch syndrome–associated cancer regardless of the age at diagnosis. CHAPTER 91 Cancer of the Bladder and Urinary Tract As genomic analysis technologies have improved, so has our under­ standing of the molecular biology unique to urothelial carcinoma. In 2017, the full bladder cancer results of The Cancer Genome Atlas (TCGA) project were published. This effort comprehensively analyzed gene mutations, fusions, expression, copy number variations, meth­ ylation, and microRNA across the genome of patients with bladder urothelial carcinoma treated with surgery. Key findings from this effort include (1) genomic alterations in genes (e.g., FGFR3, EGFR, ERBB2, ERBB3, PIK3CA, TSC1, etc.) targetable by currently approved drugs or drugs in development in 71% of patients; (2) genomic alterations in chromatin-modifying genes (KMT2D, KDM6A, KMT2C, EP300, CREBBP, etc.) in the majority of patients; (3) hypermethylation with epigenetic silencing of gene expression in one-fourth of patients; and (4) the identification by RNA sequencing of five distinct intrinsic molecular subtypes (luminal papillary, luminal infiltrated, luminal, basal squamous, and neuronal) closely resembling luminal and basal subclassifications of breast cancers. These bladder TCGA findings have led to clinical trial designs enriching for patients with specific gene mutation profiles as well as interrogation of candidate biomarkers according to intrinsic molecular subtypes. ■ ■STAGING AND OUTCOMES BY STAGE The staging of bladder cancer is dependent on the depth of invasion within the bladder wall, involvement of lymph nodes, and spread to A B PART 4 Oncology and Hematology C D FIGURE 91-1  Bladder and urinary tract cancer histologies. A. Urothelial carcinoma. B. Squamous cell carcinoma. C. Small-cell carcinoma. D. Plasmacytoid variant. (Courtesy of Alex Baras, MD, PhD, Johns Hopkins University Department of Pathology.) surrounding and distant organs as depicted in Fig. 91-2. Approxi­ mately 75% of bladder cancer presents with non–muscle-invasive bladder cancer (NMIBC), 18% with disease invading into or through the muscular wall of the bladder, and only 3% with metastatic spread to distant organs. NMIBC is defined by tumors that involve only the immediate epithelial layer of cells (carcinoma in situ [CIS] and Ta) or that only penetrate into the connective tissue below the urothelium (T1) but not into the muscular layer known as the muscularis propria. Muscle-invasive bladder cancer (MIBC) is defined by tumors that invade into the muscularis propria (T2), through the muscularis propria to involve the surrounding serosa (T3), or into immediately adjacent pelvic organs such as the rectum, prostate, vagina, or cervix (T4). Lymph node staging is classified according to involvement of a solitary node within the true pelvis (N1), two nodes involved in the true pelvis (N2), or involvement of the common iliac nodes (N3). Any disease that has spread beyond the common iliac nodes is considered metastatic (M1). The staging of bladder cancer is driven primarily by the T stage of the tumor, with stages 0a–II defined entirely by the T stage in the absence of nodal or metastatic disease. Involvement of regional lymph nodes in the true pelvis or along the common iliac artery qualifies as stage III disease, whereas involvement of any distant metastases qualifies as stage IV disease. Clinical outcomes of patients with bladder cancer correlate closely with staging at diagnosis with 5-year overall survival rates of 70–90% for disease confined to the bladder (stage I–II), 39–50% for disease that penetrates through the bladder or has spread to regional lymph nodes (stage III), and only 8% for disease extending to metastatic sites (stage IV). ■ ■TREATMENT APPROACHES Early-Stage Disease  For NMIBC, removal of all visible tumors by TURBT in the operating room is considered the mainstay of surgical treatment. Risk of recurrence can be classified as low, intermediate, or high depending on the presence of features summarized in Table 91-1. For patients with low-risk disease, meta-analyses have demonstrated a 12% reduction in early relapses when a single chemotherapy treatment of mitomycin C, epirubicin, or gemcitabine was instilled directly into the bladder (intravesical therapy) within 24 hours of the TURBT. For patients with intermediate- or high-risk tumors, weekly intravesical instillations for 6 consecutive weeks of the attenuated mycobacte­ rium strain known as Bacille Calmette-Guérin (BCG) reduce the risk of recurrence from 50 to 29%. In addition, BCG treatment has been shown to decrease the rate of progression to MIBC by 27%. Intravesical BCG is generally well tolerated. Side effects can include dysuria, uri­ nary frequency, bladder spasms, hematuria, and, in rare cases (<5%), a systemic inflammatory response that can mimic disseminated BCG infection. Following a 6-week induction BCG schedule, additional maintenance BCG treatments given according to the Southwest Bladder T-staging Bladder lymph node staging T2 T3 Muscularis propria Lamina propria T1 N3 N3 Ta N3 T4 Urothelium Tis Internal iliac artery External iliac artery Prostate* Obturator artery *Direct tumor extension into other adjacent pelvic organs (rectum, vagina, cervix) or the pelvic or abdominal walls also qualifies as T4 True pelvis border Bladder cancer prognosis according to stage N1 - Cancer spread to 1 lymph node in the true pelvis T N M Stage 5-yr survival 0is/0a M0 M0 M0 M0 M0 M1 N0 N0 N0 N0 N1-N3 Any N 96% 90% 70% 50% 36% 5% Tis/Ta T1 T2 T3 T1-T4 Any T N2 - Cancer spread to 2 lymph nodes in the true pelvis N3 - Cancer spread to lymph nodes along the common iliac artery FIGURE 91-2  Bladder cancer staging and prognosis. TNM, tumor-node-metastasis. Oncology Group schedule further reduce the risk of recurrent NMIBC compared to induction BCG alone. In patients with NMIBC that recurs long after initial BCG treatment, a repeat course of BCG can be considered. For patients with recurrence after a second adequate course of BCG or with relapsed NMIBC within 6 months of initial BCG exposure, surgical removal of the entire bladder by cystectomy is recommended due to the high risk of progression to MIBC and poten­ tially metastatic disease. For patients who are not fit enough for or who refuse cystectomy, non-BCG alternative intravesical agents (nadofara­ gene firadenovec, mitomycin C, gemcitabine, docetaxel, valrubicin) or systemically administered agents that inhibit the PD-1/PD-L1 immune checkpoint pathway (pembrolizumab) can achieve durable tumor responses in a small fraction of patients. Upper Tract Disease  In patients with urothelial carcinoma of the renal pelvis or ureter, endoscopic tissue acquisition and staging are TABLE 91-1  Non–Muscle-Invasive Bladder Cancer Recurrence Risk Groups RISK GROUP CHARACTERISTICS Low risk Initial tumor, solitary tumor, low grade, <3 cm, no CIS Intermediate risk All tumors not defined in the two adjacent categories (between the category of low and high risk) High risk Any of the following: • T1 tumor • High-grade • CIS • Multiple and large (>3 cm) Ta low-grade tumors in patients over age 70 (all conditions must be met for this point on Ta low-grade tumors) Abbreviation: CIS, carcinoma in situ. more challenging than primary tumors located in the bladder. Tumors possessing all of the following are considered low risk: solitary tumor, low grade, size <1 cm, and no invasive component on imaging. Lowrisk tumors can successfully be treated by laser ureteroscopic ablation or surgical resection and reanastomosis of the remain­ ing ureter ends in tumors that cannot be successfully eradicated endoscopically. Aorta Common iliac artery Muscle-Invasive Disease  In patients with urothelial carcinoma of the bladder that invades into or through the muscularis propria but with no evidence of metastatic spread, more aggressive therapy options summarized in Table 91-2 are required to achieve cure. In carefully selected patients with no evidence of CIS or hydronephro­ sis, bladder-sparing combined-modality therapy with concurrent chemotherapy and radiation can achieve cure in ~65% of patients. Various chemotherapy regimens have been utilized in combination with radiation including cisplatin, carboplatin, 5-fluorouracil, mitomycin C, paclitaxel, and gemcitabine. It is important to note that a maximal debulking of all visible tumor by TURBT is required prior to ini­ tiation of combined-modality therapy. In patients who achieve a complete response to combined-modality therapy, regu­ lar cystoscopic monitoring of the blad­ der is required with salvage cystectomy offered to patients who develop MIBC in follow-up. N2 N2 N1 CHAPTER 91 Cancer of the Bladder and Urinary Tract In a similar fashion, bladder-sparing partial cystectomy can be performed in a very small subset of MIBC patients. The ideal patient for partial cystectomy is the patient with a solitary, clinical T2 urothelial carcinoma in the dome of the bladder. In such patients, the tumor and immediate surrounding urothelium can TABLE 91-2  Treatment Approaches to MIBC Patients TREATMENT PATIENT SELECTION CLINICAL OUTCOMES Bladder-sparing chemoradiation No CIS, no hydronephrosis, maximal TURBT required 65% cure, 55% bladder intact, highly dependent on patient selection Bladder-sparing partial cystectomy Solitary tumors in dome of bladder are ideal Variable, highly dependent on patient selection Cystectomy Any MIBC patient 50% cure with surgery alone, highly dependent on pathologic stage Neoadjuvant cisplatin-based chemotherapy Cisplatin-eligible MIBC patients 5–10% improvement in overall survival compared to cystectomy alone Adjuvant cisplatin-based chemotherapy Cisplatin-eligible, highrisk, postcystectomy MIBC patients (pT3-4, N+) Similar improvement as neoadjuvant treatment, data less robust, many patients not suitable for adjuvant treatment Adjuvant nivolumab anti–PD-1 immunotherapy Postsurgery, high-risk MIBC and UTUC patients (pT3-4, N+, cisplatineligible after neoadjuvant therapy OR pT2-4, N+, cisplatin-ineligible who did not receive neoadjuvant therapy) 30% improvement in diseasefree survival compared to surgery alone Abbreviations: CIS, carcinoma in situ; MIBC, muscle-invasive bladder cancer; TURBT, transurethral resection of bladder tumor; UTUC, upper tract urothelial carcinoma. be resected with reconstruction of the remaining bladder to maintain near physiologic urinary function. In the majority of patients, however, resection of the entire bladder is required. In males, a cystoprostatectomy with removal of the bladder, prostate, and pelvic lymph nodes is performed, whereas in females, an anterior exenteration with removal of the bladder, uterus, ovaries, cer­ vix, and pelvic lymph nodes is performed. With the bladder removed, three options exist to reroute the urine outflow. In an ileostomy, the bilateral ureters are connected to a portion of ileum that is brought through an incision in the abdominal wall to create a stoma that drains urine into an affixed bag outside of the body. In a continent urinary reservoir or “Indiana pouch,” the ureters are connected to a portion of ileum that has been separated on both ends from the rest of the smallbowel transit to form a urinary reservoir. The remaining small bowel is reanastomosed, and the urinary reservoir is brought up just beneath the abdominal wall muscles with patients catheterizing the urinary res­ ervoir several times per day via a small stoma tract. Last, in a neoblad­ der, the same urinary reservoir described previously is brought down into the pelvis and is anastomosed to the remaining urethra to provide the opportunity to the patient to void urine through the urethra. The choice of which urinary reconstruction to perform is affected not only by patient choice but also by anatomic tumor considerations and urolo­ gist experience with each procedure. Regardless of the type of surgery performed, all patients undergo a significant catabolic change in their metabolism following removal of the bladder. While many MIBC patients are affected by weight loss preoperatively, it is not uncommon for postcystectomy patients to lose an additional 10–15 pounds in the first month postoperatively. In addition, patients can experience longterm nutritional changes such as low B12 levels due to alterations in small-bowel physiology caused by all of the urinary diversion options. PART 4 Oncology and Hematology Despite aggressive surgery, only half of patients undergoing cystec­ tomy are cured by surgery alone. Therefore, many clinical trials have investigated the role of systemic chemotherapy and immunotherapy before (neoadjuvant) or after (adjuvant) surgery. Meta-analyses have shown a 5–10% absolute overall survival advantage when combination chemotherapy regimens utilizing cisplatin have been used before sur­ gery. Importantly, non–cisplatin-containing chemotherapy regimens have proven inferior to cisplatin-containing regimens. Therefore, if patients are not suitable candidates for cisplatin administration due to poor functional status or comorbidities (e.g., poor renal function), patients should proceed directly to surgery and forego neoadjuvant therapy. A similar benefit exists with cisplatin-based combination che­ motherapy given after surgery. However, in the postoperative setting, some patients may not recover sufficiently from their surgery within a time frame optimal for chemotherapy administration. In bladder and upper tract urothelial cancer patients with high-risk postsur­ gery pathology features, adjuvant treatment with the PD-1–targeting immune checkpoint inhibitor, nivolumab, has demonstrated a 30% improvement in disease-free survival compared to observation and is considered a standard treatment option. For patients with high-risk urothelial carcinoma of the upper urinary tract, resection of the kidney and ureter (including the ureter bladder cuff) by nephroureterectomy is preferred. Segmental ureterectomy may be appropriate in patients with decreased renal function in which nephron-sparing outcomes are critical to prevent the need for dialysis. Similarly, in CIS patients, administration of BCG therapy via a nephros­ tomy tube can be considered to preserve intact renal function. The use of cisplatin-based neoadjuvant chemotherapy has been associated with a pathologic complete response at surgery of 14% in upper tract urothe­ lial carcinoma patients. Similarly, in the post-nephroureterectomy set­ ting, adjuvant platinum-based chemotherapy (carboplatin or cisplatin) reduced recurrence rates by 55% compared to surgery alone. The use of perioperative chemotherapy (before or after surgery) or PD-1–tar­ geting immunotherapy (after surgery) is now recommended for upper tract urothelial carcinoma patients in national guidelines. Metastatic Disease  For patients with metastatic urothelial carci­ noma regardless of primary tumor origin, systemic platinum-based chemotherapy remained the established initial treatment for decades. However, the regimen of a nectin-4–targeting antibody-drug con­ jugate, enfortumab vedotin, carrying the monomethyl auristatin E (MMAE) cytotoxic payload combined with the PD-1 immune check­ point inhibitor pembrolizumab (EV+P) supplanted platinum-based chemotherapy in 2023 as the preferred first-line therapy for meta­ static urothelial carcinoma patients. In a randomized, phase 3 clini­ cal trial, EV+P treatment resulted in a highly significant improved median overall survival of 31.5 months compared to 16.2 months with platinum-based chemotherapy. These results led to the FDA approval of the EV+P regimen in first-line metastatic urothelial carcinoma patients. The optimal second-line therapy for patients who experience disease progression on front-line EV+P is not defined. Second-line options include platinum-based chemotherapy or fibroblast growth factor receptor (FGFR) inhibitor therapy (erdafitinib) for patients with activating FGFR genomic alterations. For patients with progres­ sion after receiving both platinum-based chemotherapy and a PD-1/ PD-L1 immune checkpoint inhibitor, the Trop-2–targeting antibodydrug conjugate sacituzumab govitecan, containing a topoisomerase- inhibiting cytotoxic payload, SN-38, remains a third-line option. Prior to the approval of EV+P in the metastatic front-line setting, maintenance treatment with the PD-L1 immune checkpoint inhibitor avelumab had demonstrated an improvement in overall survival com­ pared to platinum-based chemotherapy alone in patients demonstrat­ ing stable disease or objective response to their front-line treatment. The role of maintenance PD-1/PD-L1 immune checkpoint inhibitor therapy in the second-line and beyond settings is undefined and is being evaluated in ongoing clinical trials. Additional novel urothelial carcinoma therapeutics are under ongoing investigation. With the increased number of therapeutic agents for metastatic urothelial cancer patients now available, differing toxicity profiles between treatment regimens commonly impact treatment decisions for individual patients. With platinum-based chemotherapy, renal insufficiency, myelosuppression, nausea, and neuropathy are common. With enfortumab vedotin, myelosuppression can occur; however, neuropathy is dose-limiting with rare but serious skin toxicity and new-onset diabetes events. Myelosuppression and significant diarrhea requiring intravenous fluid support are common with sacituzumab govitecan. In contrast, myelosuppression is uncommon with PD-1/ PD-L1 immune checkpoint inhibitors. Rare immune-related toxicities can be severe and may include colitis, pneumonitis, hepatitis, nephri­ tis, myocarditis, rash, hypothyroidism, Guillain-Barré syndrome, idiopathic thrombocytopenia purpura, and adrenal insufficiency. Lastly, erdafitinib side effects are notable for hyperphosphatemia, dystrophic nail changes, and rare central serous retinopathy. Thus, ophthalmologic evaluations are recommended for patients receiving FGFR inhibitor therapies. ■ ■FURTHER READING American Cancer Society: Cancer Facts & Figures 2023. Atlanta, GA: Available from https://www.cancer.org/cancer/bladder-cancer/ detection-diagnosis-staging/survival-rates.html. Carlo MI et al: Cancer susceptibility mutations in patients with urothelial malignancies. J Clin Oncol 38:5, 2020. Chou R et al: Intravesical therapy for the treatment of nonmuscle invasive bladder cancer: A systemic review and meta-analysis. J Urol 197:5, 2017. Coleman JA et al: Diagnosis and management of non-metastatic upper tract urothelial carcinoma: AUA/SUO guideline. J Urol 209:6, 2023. Dyrskjøt L et al: Bladder cancer. Nat Rev Dis Primers 9:1, 2023. Howlader N et al: SEER Cancer Statistics Review, 1975-2017. Avail­ able from https://seer.cancer.gov/csr/1975_2017/. Based on November 2019 SEER data submission, posted to the SEER website, April 2020. Powles T et al: Enfortumab vedotin and pembrolizumab in untreated advanced urothelial cancer. N Engl J Med 390:10, 2024. Robertson AG et al: Comprehensive molecular characterization of muscle-invasive bladder cancer. Cell 171:3, 2017. # 21 - 92 Benign and Malignant Diseases of the Prostate ### 92 Benign and Malignant Diseases of the Prostate Siegel RL et al: Cancer statistics, 2023. CA Cancer J Clin 73:1, 2023. Sylvester RJ et al: European Association of Urology (EAU) prognostic factor risk groups for non–muscle-invasive bladder cancer (NMIBC) incorporating the WHO 2004/2016 and WHO 1973 classification systems for grade: An update from the EAU NMIBC guidelines panel. Eur Urol 79:4, 2021. US Food and Drug Administration: FDA approves enfortumab vedotin-ejfv with pembrolizumab for locally advanced or metastatic urothelial cancer. Available from: https://www.fda.gov/drugs/resourcesinformation-approved-drugs/fda-approves-enfortumab-vedotin-ejfvpembrolizumab-locally-advanced-or-metastatic-urothelial-cancer. Oliver Sartor, James A. Eastham Benign and Malignant Diseases of the Prostate Benign and malignant changes in the prostate increase with age. Autopsies of men in the eighth decade of life show hyperplastic changes in >90% and malignant changes in >70% of individuals. The high prevalence of these diseases among the elderly, who often have competing causes of morbidity and mortality, mandates a risk-adapted approach to diagnosis and treatment. This can be achieved by consid­ ering these diseases as a series of states. Each state represents a distinct clinical milestone for which therapy(ies) may be recommended based on disease extent, current symptoms, risk of developing symptoms, and/or the risk of death from prostate cancer in relation to death from other causes. Given the complexities and, at times, the uncertainties of optimal decision-making, patient preferences are an important consid­ eration. For benign proliferative disorders, symptoms of bladder outlet obstruction and potential complications including urinary retention and urinary tract infection are weighed against the side effects and complications of medical or surgical intervention. For prostate malig­ nancies, the likelihood that a clinically significant cancer is present in the gland and the concomitant risk of symptoms or death from cancer are necessarily balanced against the risks and morbidities of the recom­ mended treatments. ANATOMY AND PATHOLOGY The prostate is in the pelvis and is adjacent to the rectum, the bladder, the periprostatic and dorsal vein complexes, the neurovascular bundles that are responsible for erectile function, and the urinary sphincter that is responsible for passive urinary control. The prostate is composed of branching tubuloalveolar glands arranged in lobules surrounded by fibromuscular stroma. The acinar unit includes an epithelial compartment made up of epithelial, basal, and neuroendocrine cells separated by a basement membrane and a stromal compartment that includes fibroblasts and smooth-muscle cells. Prostate-specific antigen (PSA) is produced in the epithelial cells. Both prostate epithelial cells and stromal cells express androgen receptors (ARs) and depend on androgens for growth. Testosterone, the major circulating androgen, is converted by prostatic 5α-reductase to dihydrotestosterone, a more potent androgen. The periurethral portion of the gland increases in size during puberty and after the age of 55 years due to the growth of nonma­ lignant cells in the transition zone of the prostate that surrounds the urethra. Most cancers develop in the peripheral zone, and cancers in this location may or may not be palpated during a digital rectal exami­ nation (DRE). PROSTATE CANCER The American Cancer Society’s estimates for prostate cancer in the United States for 2024 are 299,010 new prostate cancer cases and 35,250 deaths from prostate cancer. In the United States, prostate cancer is the most common nonskin malignancy in men and the sec­ ond leading cause of cancer death. The absolute number of prostate cancer deaths has decreased in the past 30 years, attributed by some to the widespread use of PSA-based detection strategies. The incidence/ mortality ratio for prostate cancer is extremely high relative to most other malignancies, and most men diagnosed with prostate cancer will not die from their disease. ■ ■EPIDEMIOLOGY Epidemiologic studies show that the risk of being diagnosed with pros­ tate cancer increases 2.5-fold if one first-degree relative is affected and even more if two or more are affected. Risk is greatest for those whose relatives are diagnosed before the age of 65. Current estimates are that 40% of early-onset and 5–10% of all prostate cancers are hereditary. Prostate cancer affects ethnic groups differently. Matched for age, African-American patients have a higher incidence and present at a more advanced stage with higher-grade, more aggressive cancers. The causes for this disparity are debated, but genetic, environmental, and societal factors are implicated. Genome-wide association studies (GWAS) have identified >100 prostate cancer susceptibility loci that are estimated to explain up to 25% of prostate cancer risk. Each prostatic risk loci typically confers only a small incremental risk of cancer, but combinations are more impactful. Some mutated genes such as BRCA2, HOXB13, ATM, and PALB2 clearly confer an increased risk of prostate cancer; however, that risk can be substantially modulated by presence or absence of additional genomic prostatic risk loci. Polygenic risk scores to better ascertain prostate cancer risk are under development but not routinely available for clinical care today. CHAPTER 92 Benign and Malignant Diseases of the Prostate The prevalence of autopsy-detected cancers is relatively similar around the world, while the incidence of clinical disease varies. In part, this is due to the substantial variations in the use of PSA screening tests. Environ­ mental and dietary factors may play a role in prostate cancer growth and progression. High consumption of dietary fats, such as α-linoleic acid or polycyclic aromatic hydrocarbons that form when red meats are cooked, is believed to increase risk. Like breast cancer in Asians, the risk of prostate cancer in Asians increases when they move to Western environ­ ments. Reasons for this are poorly understood but in part likely reflect a greater probability of PSA screening tests in the Western world. Protec­ tive factors may include consumption of lycopene found in tomatoes and inhibitors of cholesterol biosynthesis (e.g., statin drugs). Not smoking and avoiding obesity reduce the risk of disease progression. ■ ■DIAGNOSIS AND TREATMENT BY CLINICAL STATE The prostate cancer continuum—from the appearance of a preneo­ plastic and invasive lesion that is localized to the gland to a metastatic lesion causing symptoms and, ultimately, mortality—can span years to decades. To limit overdiagnosis of clinically insignificant cancers and for disease management in general, competing risks are considered in the context of a series of clinical states (Fig. 92-1). The states are defined operationally based on whether or not a cancer diagnosis has been established and, for those with a diagnosis, the state of the primary tumor (treated vs untreated), the presence of absence of metastases on imaging studies, and the measured level of testosterone in the blood. With this approach, an individual resides in only one state and remains in that state until progression. At each assessment, the decision to offer treatment and the specific form of treatment are based on the presence or absence of cancer-related symptoms and, if absent, the risk posed by the cancer relative to competing causes of morbidity and mortality that may be present in that individual. It follows that the more advanced the disease, the greater is the need for treatment. Individual decision-making and patient preferences are key for prostate cancer throughout the continuum. Considerable heterogeneity can be encountered in patients seeking treatment recommendations given widely varying perceptions of risks and benefits, especially for those with early-stage disease. Rising PSA: no visible metastases: castrate Rising PSA: no visible metastases: non-castrate Clinically localized disease No cancer diagnosis Clinical metastases: non-castrate Death from cancer exceeds death from other causes PART 4 Oncology and Hematology FIGURE 92-1  Clinical states of prostate cancer. PSA, prostate-specific antigen. For those without a cancer diagnosis, the decision to undergo testing to detect a cancer is based on the individual’s estimated life expectancy and, separately, the probability that a clinically significant cancer may be present. For those with a prostate cancer diagnosis, the clinical states model considers the probability of developing symptoms or dying from the disease. Thus, a patient with a localized tumor that has been surgically removed remains in the state of localized disease if the PSA remains undetectable. The time within a state then becomes a measure of the efficacy of an intervention. Because many patients with active cancer are not at risk for developing metastases, symptoms, or death, the clinical states model allows a distinction between cure—the elimination of all cancer cells, the primary therapeutic objective of treatment for most cancers—and cancer control, by which the tempo of the illness is determined to be so slow or has been altered by treatment to the point where it is unlikely to cause symptoms, to metastasize, or to shorten a patient’s life expectancy. Importantly, from a patient standpoint, both outcomes can be considered equivalent therapeuti­ cally assuming the patient has not experienced symptoms of the dis­ ease or the treatment needed to control it. Even when a recurrence is documented, immediate therapy is not always necessary. Rather, as at the time of diagnosis, the need for intervention is based on the tempo of the illness as it unfolds in the individual, relative to the risk-tobenefit ratio of the intervention being considered. Assessment of the future risk and tempo of the cancer, balanced with an understanding of the patient’s morbidities and life expectancy, is key to management of prostate cancer. ■ ■NO CANCER DIAGNOSIS Prevention  No agent is currently approved for the prevention of prostate cancer. The results from several large double-blind, random­ ized chemoprevention trials have established 5α-reductase inhibitors (5ARIs) as the predominant therapy to reduce the future risk of a pros­ tate cancer diagnosis; however, most of the prevented cancers were low risk, and those cancers typically require no treatment as their natural history is indolent. No drug is approved for prostate cancer prevention. Various vitamins and supplements have been studied in large-scale prostate cancer prevention trials, but no intervention has been shown to be effective. Early Detection and Diagnosis  The decision to pursue a diag­ nosis of prostate cancer must balance the benefit from detecting Clinical metastases: castrate first line Clinical metastases: castrate second line Clinical metastases: castrate third line Detectable metastases and treating clinically significant cancers that, left untreated, would adversely affect a patient’s quality and duration of life, against the morbidity associated with the overtreatment of clinically insignifi­ cant cancers highly prevalent in the general population. The balance is best approached through shared decision-making between the patient and physician; however, the complexities of the subject and the limited time available for most primary care physicians often preclude truly informed decisions. Considerations regarding whether to pursue a diagnosis include symptoms, an abnormal DRE, or more typically, a change in or elevated serum PSA. Genetic risk and family history are also relevant in the decision-making process, and those with a family history of lethal cancer represent patients of particular concern. PHYSICAL EXAMINATION  The digital rectal exam (DRE) focuses on prostate size, symmetry, consistency, and abnormalities within and/or beyond the gland. Most cancers occur in the peripheral zone and may be palpated on DRE. Carcinomas are characteristically hard, nodular, irregular, and often result in an asymmetric DRE finding. Induration may also be due to benign prostatic hyperplasia (BPH) or calculi. Over­ all, 20–25% of patients with an abnormal DRE have prostate cancer. The DRE is a not accepted as a validated prostate cancer screening test given the frequent false positives and false negatives associated with this exam. PROSTATE-SPECIFIC ANTIGEN  PSA (kallikrein-related peptidase 3; KLK3) is a kallikrein-related serine protease that causes liquefaction of seminal coagulum. It is produced by both nonmalignant and malignant epithelial cells and, as such, is prostate specific, not prostate cancer specific. Serum levels of PSA may increase from prostatitis, BPH, or prostate cancer. PSA circulating in the blood is inactive and mainly occurs as a complex with the protease inhibitor α1-antichymotrypsin and as free (unbound) PSA forms. A lower free PSA is more likely to be associated with cancer at the time of biopsy. PSA levels should be undetectable after about 6 weeks if the prostate has been completely removed (radical prostatectomy). If there is no prostate, there should be no detectable PSA. Persistence of measurable serum PSA after pros­ tate removal is typical of recurrent cancer. PSA testing was approved by the U.S. Food and Drug Administra­ tion (FDA) in 1994 for early detection of prostate cancer, and the widespread use of the test has played a significant role in the propor­ tion of patients diagnosed with early-stage cancers: today, >70–80% of newly diagnosed cancers are clinically organ confined. The level of PSA in blood is strongly associated with the risk and outcome of prostate cancer. A single PSA measured at age 60 is associated (area under the curve [AUC] of 0.90) with lifetime risk of death from prostate cancer. Most (90%) prostate cancer deaths occur among patients with PSA lev­ els in the top quartile (>2 ng/mL), although only a minority of patients with PSA >2 ng/mL will develop lethal prostate cancer. Despite this and mortality rate reductions reported from large, randomized prostate cancer screening trials, routine use of the test remains controversial given both false positives and false negatives and the fact that PSA test­ ing may lead to the diagnosis and treatment of indolent cancers that pose little risk to the patient’s overall health. The U.S. Preventive Services Task Force (USPSTF) current guideline states, “For men aged 55 to 69 years, the decision to undergo periodic PSA-based screening for prostate cancer should be an individual one. Before deciding whether to be screened, men should have an oppor­ tunity to discuss the potential benefits and harms of screening with their clinician and to incorporate their values and preferences in the decision.” The USPSTF recommends against screening men aged 70 or older. The USPSTF guideline can be accessed at https://www.uspreven­ tiveservicestaskforce.org/uspstf/draft-update-summary/prostate-cancerscreening-adults. The American Urologic Association (AUA) guidelines indicate that “clinicians should engage in shared decision-making with people for whom prostate cancer screening would be appropriate and proceed based on a person’s values and preferences.” In contrast to the USPSTF, the AUA guidelines state that “clinicians should offer prostate cancer screening beginning at age 40 to 45 years for people at increased risk of developing prostate cancer based on the following factors: Black ancestry, germline mutations, strong family history of prostate cancer.” Further, “clinicians should offer regular prostate cancer screening every 2 to 4 years to people aged 50 to 69 years.” The current AUA guide­ lines are available at https://www.auanet.org/guidelines-and-quality/ guidelines/early-detection-of-prostate-cancer-guidelines. There is no rationale for recommending PSA screening in asymp­ tomatic patients with a short life expectancy. Hence, patients over the age of 70 should only be tested in selected circumstances, such as a higher than median PSA measured before age 70 or excellent overall health. In addition, because a baseline PSA is a strong predictor of the future risk of lethal prostate cancer, patients with low PSAs, for example <1 ng/mL, can undergo testing less frequently, perhaps every 4 years, with screening possibly ending at age 60 if the PSA remains at ≤1 ng/mL Though early detection of prostate cancer can potentially reduce the risk of prostate cancer death, high proportions of patients with screendetected prostate cancer may not need immediate treatment and can be managed by active surveillance. The goal of prostate cancer screening should be to maximize the benefits of early cancer detection among patients who can benefit from treatment and minimize its harms. The PSA criteria used to recommend additional testing have evolved over time. However, based on the commonly used cut point (a total PSA ≥4 ng/mL), most patients with a PSA elevation do not have histologic evidence of prostate cancer at biopsy. In addition, many patients with PSA levels below this cut point harbor cancer cells in their prostate. Information from the large Prostate Cancer Prevention Trial demonstrates that there is no PSA below which the risk of prostate cancer is zero. Thus, the PSA level helps establish the likelihood that a person will harbor cancer if he undergoes a prostate biopsy. The goal is to increase the sensitivity of the test for younger patients harboring clinically significant cancers that may shorten survival and to reduce the frequency of detecting cancers of low malignant potential in patients more likely to die of other causes. Patients with symptomatic bacterial prostatitis should have a course of antibiotics before biopsy. However, the routine use of antibiotics in an asymptomatic person with an elevated PSA level is discouraged. SECOND-LINE SCREENING TESTS  Several tests have been developed to better stratify patients with an elevated PSA test into those more or less likely to have clinically significant prostate cancer. The 4K Score Test (OPKO Lab, Nashville, TN) measures four prostate-specific kallikreins (total PSA, free PSA, intact PSA, and human kallikrein 2). The results are combined with clinical information in an algorithm that estimates an individual’s percent risk of having an aggressive prostate cancer should that individual opt for a prostate biopsy. The Prostate Health Index (PHI; Innovative Diagnostic Laboratory, Richmond, VA) is a blood test that estimates the risk of having prostate cancer. The PHI test is a combination of free PSA, total PSA, and the [–2]proPSA isoform of free PSA. These three tests are combined in a formula that calculates the PHI score. The PHI score is a better predic­ tor of prostate cancer than the total PSA test alone or the free PSA test alone. Urine-based testing measuring exosomes (ExoDx Prostate Test) or mRNA levels of prostate cancer–related genes (Select-MDx) are also available. The most important current test to stratify risk after detection of an elevated PSA is multiparametric prostate magnetic resonance imaging (mpMRI). The mpMRI varies from a traditional magnetic resonance imaging (MRI) by including not only the T1/T2-weighted images but also measurement of diffusion-weighted imaging with or without dynamic contrast enhancement. Using a structured reading system termed the Prostate Imaging Reporting and Data System (PI-RADS), patients can be risk stratified to determine the risk of clinically sig­ nificant cancer. Data indicate that men with a PI-RADS 1–2 lesion can safely avoid biopsy, whereas patients with a PI-RADS 3–5 lesion can have targeted biopsies that are more likely to yield a true sense of the findings within the gland. The addition of an mpMRI in the prebiopsy decision-making unequivocally reduces the number of patients under­ going biopsy and reduces the diagnosis of Gleason 6 (grade group 1) cancers, without compromising the diagnosis of clinically relevant can­ cers. Today, an mpMRI of the prostate should be obtained in most cases prior to performing a prostate biopsy. Doing so will reduce the number of patients who are recommended to have a biopsy and improve the accuracy of the biopsies that are performed. CHAPTER 92 Benign and Malignant Diseases of the Prostate PROSTATE BIOPSY  A diagnosis of cancer is established by an imageguided needle biopsy. Direct visualization of the gland by transrectal ultrasound (TRUS), MRI, or fusion of the ultrasound and MRI images ensures that all areas of the gland, including suspicious areas, are sampled. Contemporary schemas advise an extended-pattern 12-core biopsy that includes sampling from the peripheral zone as well as a lesion-directed palpable nodule or suspicious image-guided sampling. MRI-guided biopsy is superior to that of ultrasound-guided biopsy in terms of ascertaining an accurate depiction of the prostate pathology. Patients with an elevated PSA and a negative biopsy should continue to be followed as a negative biopsy does not rule out a future diagnosis of cancer. PATHOLOGY  Each core of the biopsy is examined for the presence of cancer, and the amount of cancer should be quantified based on the length of the cancer within the core and the percentage of the core involved. Of the cancers identified, >95% are adenocarcinomas; the rest are squamous or transitional cell tumors or, rarely, carcinosarco­ mas or small-cell histologies. Metastases to the prostate are rare, but colon cancers or transitional cell tumors of the bladder can invade the gland by direct extension. When prostate cancer is diagnosed, a measure of histologic aggres­ siveness is assigned using the Gleason grading system, in which the dominant and secondary glandular histologic patterns are scored from 1 (well differentiated) to 5 (undifferentiated) and summed to give a total score of 6–10 for each tumor. The most poorly differentiated area of tumor (i.e., the area with the highest histologic grade) often determines biologic behavior. The presence or absence of perineural invasion and extracapsular spread should also be recorded. Over the years, the Gleason grading system has undergone several changes. Currently, Gleason total scores of 2–5 are no longer assigned, and in practice, the lowest total score now assigned is 6. This leads to a logical yet incorrect assumption on the part of patients that a Gleason 6 cancer is in the middle of the scale, triggering the fear that their can­ cer is serious and the assumption that treatment is necessary despite TABLE 92-1  TNM Classification TNM (tumor, node, metastasis) Staging System for Prostate Cancera Tx Primary tumor cannot be assessed T0 No evidence of primary tumor Localized Disease T1 Clinically inapparent tumor, neither palpable nor visible by imaging T1a Tumor incidental histologic finding in ≤5% of resected tissue; not palpable T1b Tumor incidental histologic finding in >5% of resected tissue T1c Tumor identified by needle biopsy (e.g., because of elevated PSA) T2 Tumor confined within prostateb T2a Tumor involves half of one lobe or less T2b Tumor involves more than one half of one lobe, not both lobes T2c Tumor involves both lobes Local Extension T3 Tumor extends through the prostate capsulec T3a Extracapsular extension (unilateral or bilateral) T3b Tumor invades seminal vesicles T4 Tumor is fixed or invades adjacent structures other than seminal vesicles such as external sphincter, rectum, bladder, levator muscles, and/or pelvic wall PART 4 Oncology and Hematology Metastatic Disease N1 Positive regional lymph nodes M1 Distant metastases aRevised from SB Edge et al (eds): AJCC Cancer Staging Manual, 7th ed. New York, Springer, 2010. bTumor found in one or both lobes by needle biopsy, but not palpable or reliably visible by imaging, is classified as T1c. cInvasion into the prostatic apex or into (but not beyond) the prostatic capsule is classified not as T3 but as T2. Abbreviation: PSA, prostate-specific antigen. Gleason score 6 being favorable risk. To address these issues, a new five-grade group system has been developed: Grade group 1 (Gleason score ≤6) Grade group 2 (Gleason score 3 + 4 = 7) Grade group 3 (Gleason score 4 + 3 = 7) Grade group 4 (Gleason score 4 + 4 = 8) Grade group 5 (Gleason scores 9 and 10) The new system simplifies the grading of prostate cancer, appropri­ ately classifying the lowest risk as grade group 1 (rather than Gleason score 6), and accurately predicts prognosis. PROSTATE CANCER STAGING  The TNM (tumor, node, metastasis) staging system includes categories for cancers that are identified solely based on an abnormal PSA (T1c), those that are palpable but clinically confined to the gland (T2), and those that have extended outside the gland (T3 and T4) (Table 92-1 and Fig. 92-2). DRE alone is inaccurate A B C D FIGURE 92-2  T stages of prostate cancer. A. T1—Clinically inapparent tumor, neither palpable nor visible by imaging. B. T2—Tumor confined within prostate. C. T3—Tumor extends through prostate capsule and may invade the seminal vesicles. D. T4—Tumor is fixed or invades adjacent structures. Eighty percent of patients present with local disease (T1 and T2), which is associated with a 5-year survival rate of 100%. An additional 12% of patients present with regional disease (T3 and T4 without metastases), which is also associated with a 100% survival rate after 5 years. Four percent of patients present with distant disease (T4 with metastases), which is associated with a 30% 5-year survival rate. (Three percent of patients are ungraded.) (© 2010 Memorial Sloan-Kettering Cancer Center, New York, NY. All rights reserved. Republished with permission.) in determining the extent of disease within the gland, the presence or absence of capsular invasion, involvement of seminal vesicles, and extension of disease to lymph nodes. Unfortunately, no single test has been proven to perfectly indicate the stage or the presence of organconfined disease, seminal vesicle involvement, or lymph node spread in part due to fact that cancer cells can microscopically spread below the limits of sensitivity for any imaging test. That said, mpMRI imag­ ing can often reveal evidence of extracapsular spread or seminal vesicle invasion with a higher degree of accuracy than DRE, and taking MRI findings into account is typically done in staging today. Prognosis and classification for nonmetastatic prostate cancer are typically done in three broad categories (low, intermediate, and high risk). Low-risk tumors are confined to the prostate with a PSA of <10 ng/mL and grade group 1. Intermediate-risk tumors are confined to the prostate, have a PSA between 10 and 20 ng/mL, or are grade group 2 or 3 (Gleason 7). This category is typically divided into a “favor­ able” and “unfavorable” intermediate risk depending on grade group 2 (favorable) or 3 (unfavorable) and number of positive biopsies (>50% of cores positive for cancer is unfavorable). High-risk tumors extend outside the prostate, have a PSA >20 ng/mL, or are grade group 4 or 5 (Gleason 8–10). There is also a subset of high-risk tumors termed “very high risk” in which the cancer extends into the seminal vesicles (T3b) or adjacent organs, i.e., rectum or bladder (T4), or there are multiple biopsy samples with high-grade cancer. Computed tomography (CT) lacks sensitivity and specificity to detect extraprostatic extension and is inferior to MRI in visualization of lymph nodes. In general, mpMRI is superior to CT to detect cancers in the prostate, to assess local disease extent, and fused with ultrasound imaging, to guide sites to biopsy within the gland. Thus, mpMRI can be quite useful for the planning of surgery and radiation therapy. The use of prostate-specific membrane antigen (PSMA) positron emission tomography (PET) scans has radically altered the assessment of prostate cancer spread beyond the prostate. This scan is now FDA approved for patients with intermediate- and high-risk prostate cancer and is substantially more sensitive and accurate in the detection of metastases as compared to conventional imaging (including MRI). Currently, state-of-the-art staging for Gleason grade group 3 and higher patients involves PSMA PET imaging before treatment. PSMA PET scans significantly improve specificity over conventional imaging while maintaining comparable sensitivity. PSMA PET scans are not capable of detecting low-volume microscopic disease. In studies where surgically removed lymph nodes were assessed for metastatic prostate cancer, sensitivity was consistently <50%. Simply stated, PET scans cannot detect microscopic disease (<2 mm focus), and a negative scan cannot rule out the possibility of cancer spread. We emphasize that no test is capable of microscopic cancer detection and note that a “nega­ tive” scan is not equated with the definitive absence of cancer. Radionuclide bone scans (bone scintigraphy) have been used in the past to evaluate spread to osseous sites. This test is insensitive relative to PSMA PET and nonspecific because it does not detect the cancer itself, only reaction of the bone in the presence of the cancer. Staging early-stage cancers with a bone scan is much less effective than using PSMA PET, and most centers no longer routinely use bone scans for initial staging in patients with suspected localized cancer given its known insensitivity and propensity for false-positive findings. TREATMENT Prostate Cancer CLINICALLY LOCALIZED PROSTATE CANCER Patients with clinically localized disease are typically managed by radical prostatectomy, radiation therapy, or active surveillance. Choice of therapy requires the consideration of several factors: the presence of symptoms, the probability that the untreated tumor will adversely affect the quality or duration of survival, and the probability that the tumor can be cured by single-modality therapy directed to the prostate versus requiring combinations of both local and systemic therapy. There is no clear evidence for the superiority of any one form of local therapy relative to another. This is due to the lack of prospec­ tive randomized trials, referral bias and physician bias, variation in the experience of the treating teams, and differences in trial end points and the definitions of cancer control. Often, PSA relapsefree survival is used because an effect on metastatic progression or survival may not be apparent for years (if ever). A PSA recurrence does not necessarily mean that the disease will cause symptoms or shorten survival. The rate at which PSA doubles (PSA doubling time [PSADT]) is an important predictor of future clinical impact. Those with a PSADT of 14 months or greater are at low risk of clinical consequences, while those with a more rapid PSADT, espe­ cially those with a doubling time of 3 months or less, are at much higher risk for future clinically relevant events. Understanding the PSADT and the age/comorbidities of the patient is essential for decision-making. After radical surgery to remove all prostate tissue, PSA should become undetectable in the blood within 6 weeks. If PSA remains or becomes detectable after radical prostatectomy, the patient is considered to have persistent or recurrent disease. A patient with no prostate should have no detectable PSA. After radiation therapy, in contrast, PSA does not become undetectable because the remaining nonmalignant elements of the gland continue to produce PSA even if the cancer cells have been eliminated. Similarly, cancer control is not well defined by PSA for a patient managed by active surveillance. For patients with an intact prostate and a PSA of <10 ng/mL, the fluctuations in PSA are more reflec­ tive of the benign rather than malignant cells in the prostate. Other outcomes are time to objective progression (local or systemic), cancer-specific survival, and overall survival; however, these out­ comes may take years to ascertain; thus, studies of localized disease are necessarily large, long, and often quite expensive. The more extensive the local disease, the higher the probability of regional lymph node involvement (even when imaging studies are normal), the lower the probability of local control, and the higher the probability of relapse and the development of metastases. More important is that within the categories of clinical stage T1, T2, and T3 disease are cancers with a range of prognoses. Some T3 tumors are curable with therapy directed solely at the prostate, and some T1 lesions have a high probability of systemic relapse that requires the integration of local and systemic therapy to achieve cure. For T1c cancers, stage alone is inadequate to predict outcome and select treatment; other factors (especially Gleason score) must be considered. Genomic stratification of risk is increasingly viewed as important, and tools such as transcriptomic profiling may one day be routinely used in addition to traditional pathology. To better assess risk and guide treatment selection, many groups have developed prognostic models or nomograms that use a com­ bination of the initial clinical T stage, biopsy Gleason score, number of biopsy cores in which cancer is detected, and baseline PSA. Not all variables are equally important, and Gleason score is required to make accurate prognostication. Some prognostic models use discrete cut points, as mentioned above (PSA <10 or ≥10 ng/mL; Gleason score of ≤6, 7, or ≥8), while others employ nomograms that use PSA and Gleason score as continuous variables. More than 100 nomograms have been reported to predict (1) the probability that a clinically significant cancer is present, (2) disease extent (organconfined vs non–organ-confined, node-negative or -positive), or (3) the relative probability of treatment success for specific local therapies using pretreatment variables. Exactly what probability of success or failure would lead a physi­ cian to recommend and a patient to seek alternative approaches is controversial and highly dependent on the age and comorbidities of the patient. As an example, it may be appropriate to recommend radical surgery for a younger patient with intermediate-risk disease, while recommending surveillance for an older patient with a tumor having identical characteristics. Nomograms and various biomark­ ers are being refined continually to incorporate additional clinical parameters and biologic determinants that can affect outcomes, making treatment decisions a dynamic process. Patient prefer­ ences are also critically important in shared decision-making. Side effects of therapy are not the same for various treatment options, and patient preferences for one approach or another may require careful discussions that extend beyond the simple calculations of risk and benefit. CHAPTER 92 Radical Prostatectomy  The goal of radical prostatectomy is to excise the cancer completely with a clear margin, to maintain conti­ nence by preserving the external sphincter, and to preserve potency by sparing the autonomic nerves in the neurovascular bundle. The procedure is advised for patients with a life expectancy of 10 years or more with a Gleason score 7 or higher disease. Radical prostatectomy can be performed via a retropubic or perineal approach or via a min­ imally invasive robotic-assisted or handheld laparoscopic approach. Outcomes can be predicted using postoperative nomograms that consider pretreatment factors and the pathologic findings at surgery. PSA failure is usually defined as a value >0.1 or 0.2 ng/mL, but as stated above, the patient without a prostate should typically have no detectable PSA. Specific criteria to guide the choice of one surgical approach over another are lacking. Minimally invasive approaches offer the advantage of a shorter hospital stay and reduced blood loss. Rates of cancer control, recovery of continence, and recovery of erectile function are comparable for robotic and open surgery. The individual surgeon, rather than the surgical approach used, is most important in determining outcomes after surgery. Benign and Malignant Diseases of the Prostate Neoadjuvant hormonal treatment with gonadotropin-releasing hormone (GnRH) agonists/antagonists alone has also been explored to improve the outcomes of surgery for high-risk patients using a variety of definitions. The results of several large trials evaluating 3 or 8 months of androgen depletion before surgery have not been shown to improve clinically relevant outcomes. Currently, neoadju­ vant hormonal therapies are not considered to be standard of care for surgically treated patients. Factors associated with incontinence following radical prosta­ tectomy include older age and membranous urethral length, which impacts the ability to preserve the urethra beyond the apex and the distal sphincter. The skill and experience of the surgeon are also critical factors. The likelihood of recovery of erectile function is associated with younger age, quality of erections before surgery, and the absence of damage to the neurovascular bundles. In general, erectile func­ tion begins to return ~6 months after surgery if neurovascular tissue has been preserved. Potency is reduced by half if at least one neurovascular bundle is sacrificed. Overall, with the availability of drugs such as sildenafil, intraurethral inserts of alprostadil, and intracavernosal injections of vasodilators, many patients recover satisfactory sexual function. Radiation Therapy  Radiation therapy is given by external beam, by radioactive sources implanted into the gland, or by a combina­ tion of the two techniques. Contemporary external beam intensity-modulated radiation therapy (IMRT) permits shaping of the dose and allows the delivery of higher doses to the prostate and a dramatic reduction in normal tissue exposure compared to three-dimensional conformal treat­ ment alone. These advances have enabled the safe administration of doses >78 Gy and resulted in higher local control rates and fewer side effects. Proton beam radiation has not been demonstrated to have superior outcomes as compared to conventional radiation with IMRT. Lack of randomized studies prevents the use of routinely adopting proton beam as a standard of care. Cancer control after radiation therapy has been defined by vari­ ous criteria, including a decline in PSA to <0.5 or 1 ng/mL, “non­ rising” PSA values, and (rarely) a negative biopsy of the prostate 2 years after completion of treatment. The standard definition of biochemical failure is a rise in PSA by ≥2 ng/mL higher than the lowest PSA achieved; however, newer data question whether the cut­ off should be lower, particularly in those with higher grade cancers. Radiation dose is critical to the eradication of prostate cancer. In a representative study, a PSA nadir of <1.0 ng/mL was achieved in 90% of patients receiving 81.0 Gy versus 76% and 56% of those receiving 70.2 and 64.8 Gy, respectively. Positive biopsy rates at 2.5 years were 4% for those treated with 81 Gy versus 27% and 36% for those receiving 75.6 and 70.2 Gy, respectively. Higher doses of radiation, however, may be associated with a higher risk of adverse events. PART 4 Oncology and Hematology Hypofractionation schedules, utilizing fewer treatments of higher radiation doses, have been evaluated and shown to provide good cancer control rates based on posttreatment biopsies showing no evidence of cancer, with no apparent increase in treatmentrelated morbidity. Hypofractionated treatments can range from as few as 5 treatments to upward of 26 treatments, with both regimens representing substantial reductions in treatment length. Multiple clinical trials have evaluated the use of androgen depri­ vation therapy (ADT) in combination with radiation. In patients with unfavorable intermediate-risk prostate cancer, short-course ADT (6 months), when combined with external beam radiotherapy, has demonstrated significant improvements in overall survival. Higher doses of radiation cannot substitute for ADT. In patients with high-risk localized disease, longer courses of ADT (18–36 months) have proven superior to shorter courses and represent the current standard of care when combined with radiotherapy. Novel genomic and transcriptomic biomarkers are being explored to assess the responsiveness of tumors to ADT, but as of yet, there are no accepted biomarkers that determine who should or should not receive ADT. Artificial intelligence assessments are promising, and new assays suggest the possibility that prostate cancers treated with radiation can be stratified into those that do and do not benefit from androgen deprivation. For patients with nonmetastatic cancer by conventional imaging (bone scan, CT, or MRI) and two or more high risk factors (Gleason 8–10, stage T3/T4, or PSA ≥40 ng/mL) or positive pelvic lymph nodes, a large randomized trial demonstrated that the addition of abiraterone/prednisone to 2 years of ADT and radiotherapy is supe­ rior to 3 years of ADT and radiotherapy. This study defined a new standard of care for these particularly high-risk patients. The Prostate Testing for Cancer and Treatment (ProtecT) trial investigated the effects of active monitoring, radical prostatectomy, and radical radiotherapy with hormones on patient-reported out­ comes in patients diagnosed with predominantly low-risk prostate cancer (~75% with Gleason score 6 or grade group 1 cancer). Cancer outcomes were essentially the same for these three approaches. Patient-reported outcomes among 1643 patients who completed questionnaires before diagnosis, at 6 and 12 months, and annually thereafter were compared. Of the three treatments, prostatectomy had the greatest negative effect on sexual function and urinary continence, and although there was some recovery, these outcomes remained worse in the prostatectomy group than in the other groups throughout the trial. The negative effect of radiotherapy on sexual function was greatest at 6 months, but sexual function then recovered somewhat and was stable thereafter; radiotherapy had little effect on urinary continence. Sexual and urinary function declined gradually in the active-monitoring group. Bowel function was worse in the radiotherapy group at 6 months than in the other groups but then recovered somewhat, except for the increasing fre­ quency of bloody stools; bowel function was unchanged in the other groups. Urinary voiding and nocturia were worse in the radio­ therapy group at 6 months but then mostly recovered and were like the other groups after 12 months. Effects on quality of life mirrored the reported changes in function. No significant differences were observed among the groups in measures of anxiety, depression, or general health-related or cancer-related quality of life. Taken together, both surgery and radiation had clear side effects, but these side effects were distinct. Brachytherapy  Brachytherapy is the direct implantation of radio­ active sources into the prostate. It is based on the principle that the deposition of radiation energy in tissues decreases as a function of the square of the distance from the source (Chap. 78). The goal is to deliver intensive irradiation to the prostate, minimizing the exposure of the surrounding tissues. The current standard tech­ nique achieves a more homogeneous dose distribution by delivering radiation according to a customized template based on imaging assessment of the cancer and computer-optimized dosimetry. The implantation is typically performed transperineally as an outpatient procedure with real-time imaging. Improvements in brachytherapy techniques have resulted in fewer complications and a marked reduction in local failure rates. In a series of 197 patients followed for a median of 3 years, 5-year actuarial PSA relapse–free survival for patients with pretherapy PSA levels of 0–4, 4–10, and >10 ng/mL were 98, 90, and 89%, respectively. In a separate report of 201 patients who underwent posttreatment biopsies, 80% were negative, 17% were indetermi­ nate, and 3% were positive. The results did not change with longer follow-up. Brachytherapy is well tolerated, although most patients experience urinary frequency and urgency that can persist for several months. Higher complication rates are observed in patients who have undergone a prior transurethral resection of the prostate (TURP), while those with obstructive symptoms at baseline are at a higher risk for retention and persistent voiding symptoms. Proctitis has been reported in <2% of patients. Like surgery, brachytherapy is best performed by those well-practiced in the technique. Active Surveillance  With the advent of PSA testing, many patients are diagnosed with low-risk prostate cancers that may not pose a threat to either the quantity or quality of a person’s life. Active surveillance, described previously as watchful waiting or deferred therapy, initially evolved from (1) studies that evaluated predominantly elderly patients with well-differentiated tumors (Gleason 6 or grade group 1) who remained untreated and demon­ strated no clinically significant progression for protracted periods, (2) recognition of the contrast between incidence and disease- specific mortality, (3) the high prevalence of autopsy cancers, and (4) an effort to reduce overtreatment and treatment-related side effects. In practice, active surveillance is the treatment recom­ mended to patients with cancers of low aggressiveness that can be safely monitored at fixed intervals with DREs, PSA measurements, imaging (best done with prostate mpMRI), and repeat prostate biopsies as indicated until histopathologic or serologic changes correlative of progression warrant treatment with curative intent. It is important to recognize that no treatment has proven superior to active surveillance for those with PSA-detected grade group 1 (Gleason score 6) disease. Surveillance remains underutilized today, and needless morbidity can result from overtreatment of those who have little chance to benefit from therapy given the indolent nature of the vast majority of patients with Gleason 6 localized disease. Case selection is critical, and determining the clinical parameters predictive of cancer aggressiveness that can be used to reliably select patients most likely to benefit from active surveillance is an area of intense study. One set of criteria includes patients with clinical T1c tumors that are biopsy Gleason grade 6. Nomograms to help predict which patients can safely be managed by active surveillance con­ tinue to be refined, and as their predictive accuracy improves, it can be anticipated that more patients will be candidates. Older patients and those with substantial comorbidities can have more permissive criteria for surveillance including those with Gleason 3 + 4 = 7 (grade group 2) localized disease. Treatment decision-making for all localized prostate cancers depends on both the characteristics of the cancer and the age and comorbidities of the patient. Anxiety remains a problem for some patients with untreated cancers, and management of that anxiety can at times be problematic. RISING PSA AFTER DEFINITIVE LOCAL THERAPY Patients in this state include those in whom the sole manifestation of disease is a rising PSA after surgery and/or radiation therapy. For most of these patients in the initial phases, there is no evidence of disease on imaging studies. For these patients, the central issue is whether the rise in PSA results from persistent disease in the pri­ mary site, systemic disease, or both. Disease in the primary site may still be curable by additional local treatment. The decision to recommend radiation therapy after prosta­ tectomy is guided by the age and comorbidities of the patient, pathologic findings at surgery, the timing of PSA failure, the PSA doubling time, and the PSA level at the time of failure. Traditional imaging (MRI, CT, and radionucleotide bone scans), especially at low levels of PSA, is typically uninformative, but newer imaging methods may or may not be useful. New PET tracers such as 18F-fluciclovine and 18F- or 68Ga-PSMA that directly image the cancer are more sensitive and can detect low-volume disease in the prostate bed or other sites to better inform the decisions regarding treatment. Detection rates, both in and outside the prostate bed, correlate with the absolute level of PSA and the rate of PSA rise. Factors that predict for response to salvage radiation therapy after radical prostatectomy are a positive surgical margin, lower Gleason score in the surgical specimen, a long interval from surgery to PSA failure, slower PSA doubling time, a low (<0.5 ng/mL) PSA value at the time of radiation treat­ ment, and the absence of distant disease when using a PSMA or fluciclovine PET scan. For patients with a rising PSA after radiation therapy, salvage local therapy can be considered if persistent disease has been docu­ mented by a biopsy of the prostate and if no disease is detectable outside of the prostate bed or regional lymph nodes by imaging. Unfortunately, case selection is poorly defined in most series. Local treatment options for patients with recurrence after radiation include salvage radical prostatectomy, salvage cryotherapy, salvage radiation therapy, and salvage high-intensity focused ultrasound. Unfortunately, morbidities can be significant in the postradiated patient. A rise in PSA after surgery or radiation therapy may indicate subclinical or micrometastatic disease with or without local recur­ rence. The need for treatment depends, in part, on the estimated probability that the patient will develop clinical symptoms and in what time frame. That immediate therapy is not always required was shown in a well-annotated series where patients who developed a rising PSA after radical prostatectomy received no systemic ther­ apy until metastatic disease was documented. Overall, the median time to metastatic progression was 8 years, and 63% of the patients with rising PSA values remained free of metastases at 5 years. Fac­ tors associated with progression included the Gleason score of the radical prostatectomy specimen, time to recurrence after surgery, and PSADT. For those with Gleason score ≥8, the probability of metastatic progression was 37, 51, and 71% at 3, 5, and 7 years, respectively. If the time to recurrence was <2 years and PSADT was long (>10 months), the proportions with metastatic disease at the same time intervals were 23, 32, and 53%, versus 47, 69, and 79% if the doubling time was short (<10 months). PSADTs are also prognostic for survival. Most physicians advise treatment when PSA doubling times are ≤10 months. A difficulty with predicting the risk of metastatic spread, symptoms, or death from disease in the rising PSA state is that many patients receive some form of therapy before the development of metastases as detected by conventional imaging. Nevertheless, predictive models continue to be refined with a consensus that lower risk patients can be watched, whereas higher risk patients may require some inter­ vention. Given that new molecular imaging techniques are now FDA approved, the interplay between imaging and risk continues to be refined. METASTATIC DISEASE: NONCASTRATE The state of noncastrate metastatic disease includes patients with metastases visible on an imaging study at the time of diagnosis or after local therapy(ies) who have noncastrate levels of testosterone (>50 ng/dL). The prognosis is distinct for those with metastases detected by conventional imaging versus those detected only with molecular imaging. Symptoms of metastatic disease may include pain from osseous spread, although many patients are asymptom­ atic despite extensive spread. Less common are symptoms related to weight loss, fatigue, malaise, lymphedema, marrow infiltration by tumor (myelophthisis), coagulopathy, blood clots, or spinal cord compression. Standard treatment is to deplete or lower androgens via ADT by medical or surgical means, the latter being the least acceptable to patients. More than 90% of male hormones originate in the testes; <10% are synthesized in the adrenal gland (Fig. 92-3). CHAPTER 92 Testosterone-Lowering Agents  Medical therapies that lower tes­ tosterone levels include the GnRH agonists/antagonists, pure GnRH antagonists, 17,20-lyase inhibitors, CYP17 inhibitors, and estrogens such as oral diethylstilbestrol (DES) (Fig. 92-3). DES is not utilized today due to the excessive risk of vascular complica­ tions that include fluid retention, phlebitis, emboli, and stroke. GnRH agonists, such as leuprolide acetate and goserelin acetate, ini­ tially produce a very brief rise in luteinizing hormone and folliclestimulating hormone followed by a downregulation of receptors in the pituitary gland, which causes a chemical castration. Regulatory approval was based on randomized trials showing reduced cardio­ vascular toxicities relative to DES, with equivalent potency. The ini­ tial rise in testosterone may occasionally result in a clinical flare of the disease, and as such, these agents are relatively contraindicated in patients with significant urinary obstructive symptoms, cancerrelated pain, or spinal cord compromise. AR antagonists that block testosterone binding to the receptor are commonly used to reduce the risk of flare. Increases in testosterone do not occur with GnRH antagonists such as degarelix, given by injection, or relugolix, given orally, and these agents as well as abiraterone acetate rapidly achieve castrate levels of testosterone. Benign and Malignant Diseases of the Prostate Agents that lower testosterone are associated with an androgendeprivation syndrome that includes hot flushes, weakness, fatigue, loss of muscle mass, risk of osteoporosis and fracture, anemia, changes in cognition and personality, and depression. Changes in lipids, obesity, and insulin resistance and an increased risk of diabetes and cardiovascular disease may also be seen, along with a decrease in bone density that worsens over time and may result in an increased risk of clinical fractures. This is a particular concern in patients with preexisting osteopenia that results from hypogonadism that may be worsened with steroid or alcohol use and significantly underappreciated. Baseline fracture risk can be assessed using the FRAX scale, and to minimize fracture risk, patients can be advised to take a bisphosphonate or RANK-ligand inhibitor (denosumab) in combination with calcium and vitamin D supplementation. Hot flushes may be ameliorated by oxybutynin or certain antidepressants such as venlafaxine. Antiandrogens  Nonsteroidal first-generation antiandrogens such bicalutamide and nilutamide have largely been replaced by the more potent next-generation agents (enzalutamide, apalutamide, and darolutamide) that do not lower serum androgen levels and result in fewer hot flushes, less of an effect on libido, less muscle wasting, fewer personality changes, and less bone loss relative to Hypothalamus GnRH CRH Pituitary GnRH agonists GnRH antagonists Degarelix Relugolix Estrogens Prednisone ACTH LH Testis Adrenal glands CYP17 inhibitors abiraterone PART 4 Oncology and Hematology Testosterone Androstenedione DHEA DHEA-S Dutasteride Prostate DHT Prostate cell Next generation anti-androgens AR Enzalutamide Apalutamide Darolutamide AR AR DHT AR Prostate cell nucleus AR DHT ARE DNA FIGURE 92-3  Sites of action of different hormone therapies. testosterone-lowering therapies. However, over time, testosterone levels increase and are converted to estrogen, which can result in mastalgia and gynecomastia that limits long-term use. The side effect of antiandrogens as monotherapy can be prevented in part by tamoxifen, aromatase inhibitors, or prophylactic breast irradiation. Most reported randomized trials in metastatic patients suggest that the cancer-specific outcomes are inferior when antiandrogens are used alone. Bicalutamide, even at a dose of 150 mg (three times the approved dose for use in combination in GnRH agonists), resulted in a shorter time to progression and inferior survival com­ pared to surgical castration for patients with established metastatic disease. Newer studies for those without metastatic disease suggest that enzalutamide is appropriate in selected patients with a PSADT of 10 months or less. Improving on the outcomes with ADT alone was a focus of the field for decades. Older antiandrogens such as bicalutamide or flu­ tamide did not convincingly achieve these goals. Practice standards changed when an improvement in time to progression and overall survival was shown when ADT was combined with docetaxel rela­ tive to ADT alone. The greatest benefit was seen for patients with “high-volume” disease defined as the presence of ≥4 lesions on radionuclide bone scan or visceral disease. Longer progressionfree and overall survival times have been noted in separate phase 3 trials comparing ADT with abiraterone, a CYP17 inhibitor that blocks androgen synthesis, and ADT with the AR antagonists such as enzalutamide and apalutamide versus the ADT standard, further changing the standard of care. Intermittent Androgen Deprivation Therapy  One way to reduce the side effects of androgen depletion is to administer hormonal therapy on an intermittent basis; however, the use of this approach in metastatic disease has yet to be proven useful for those being treated with ADT plus a novel hormone such as abiraterone, apalu­ tamide, or enzalutamide. Additional studies in the metastatic set­ ting with intermittent therapy are under consideration. Chemotherapy  Studies with ADT plus docetaxel indicate that patients with high-volume metastatic disease benefit from the addition of docetaxel. However, more recent studies indicate that ADT and docetaxel are not appropriate choices today given that the addition of abiraterone or darolutamide is superior to that of ADT plus docetaxel. Consultation with a clinician practiced in the art of advanced prostate cancer is appropriate given the rapidly changing standards of care. Outcomes of Androgen Deprivation  The anti–prostate cancer effects of the various newer androgen depletion strategies (abi­ raterone, apalutamide, or enzalutamide in combination with medical or surgical castration) are similar, and the clinical course is predict­ able: an initial response, a period of stability in which tumor cells are dormant and nonproliferative, followed after a variable period of time by a rise in PSA and regrowth that is visible on a scan as a castration-resistant lesion. Androgen depletion is not curative because cells that survive castration are present when the disease is first diagnosed. Considered by disease manifestation, PSA levels return to normal in 60–70% of patients, and measurable disease regression occurs in >50%. Duration of survival is inversely pro­ portional to disease extent at the time androgen depletion is first started and the nadir level of PSA at 6–8 months. Patients with nadir PSA values >4 ng/mL have markedly inferior survival times and should be considered for alternative approaches. METASTATIC DISEASE: CASTRATE Castration-resistant prostate cancer (CRPC), disease that pro­ gresses while the measured levels of testosterone in the blood are 50 ng/mL or lower, can produce some of the most feared complica­ tions of the disease and is lethal for most patients. The most com­ mon manifestation is a rising PSA, frequently co-occurring with progression in bone. Nodal and/or visceral progression is less fre­ quent. Symptoms may or may not be present. Critical for manage­ ment is that therapeutic objectives be based on the manifestations of the disease in the individual at the time a change in therapy is being considered. As such, for the patient with symptomatic bone disease, relief of pain can be more clinically relevant than lowering the PSA. Naturally, for all patients, the central focus is delaying or preventing disease progression, symptoms, and death from disease. Through 2010, docetaxel was the only FDA-approved life- prolonging therapy for CRPC. Since then, our understanding of the biology of the disease has increased significantly, which in turn has led to improved therapies. It is now recognized that the majority of metastatic CRPCs continue to express the AR and remain AR sig­ naling dependent. For those with progression after ADT alone, the next-generation antiandrogen enzalutamide and the CYP17 inhibi­ tor abiraterone acetate (given in combination with prednisone) have been proven to prolong life and are FDA approved for use in CRPC in both the pre- and postchemotherapy setting. Large-scale molecular profiling efforts have led to a biologically based disease taxonomy that continues to evolve and showed a mark­ edly higher than expected frequency of germline (~6% of patients) and somatic BRCA (also ~6% of patients) alterations, along with other genes in the DNA damage repair pathway that have been targeted successfully with poly-ADP ribose polymerase (PARP) inhibitors of which two, olaparib and rucaparib, are FDA approved as monothera­ pies. Combinations of abiraterone and olaparib are FDA approved for BRCA1/BRCA2-mutated CRPC patients, and enzalutamide/talozapa­ rib combinations are approved for BRCA1/BRCA2-mutated patients and other DNA repair pathway mutations. Also approved are the checkpoint inhibitors pembrolizumab and dostarlimab for tumors with high microsatellite instability (MSI) scores, mismatch repair gene deficiency, or patients with a high tumor mutational burden. These alterations are found in ~3% of prostate cancers. Other classes of therapy approved for selected CRPC patients based on demonstrated survival benefits include the biologic agent sipuleucel-T, the second-generation taxane cabazitaxel, the α-emitting bone-targeting radiopharmaceutical radium-223, and the PSMA-directed radionuclide therapy 177-lutetium PSMA-617. The use of 177-lutetium PSMA-617 has garnered intense interest given that this targeted form of radiation was able to extend sur­ vival in patients who had exhausted most conventional forms of therapy. Overall, an intense focus of current CRPC research is to understand the optimal sequence in which to utilize these agents to maximize benefit for the individual patient. Most of these agents are also being tested earlier in the course of the disease when tumor burdens are lower and the disease less heterogeneous. The result has been an increase in the frequency of late-state tumors that have undergone a lineage transformation from epithelial to alternative phenotypes (neuroendocrine and more) and are highly resistant to available therapies. Pain Management  Pain secondary to osseous metastases is one of the most feared complications of the disease and a major cause of morbidity, worsened by the narcotics needed to control symptoms. Management requires accurate diagnoses because noncancer eti­ ologies including degenerative disease, spinal stenosis, and vertebral TABLE 92-2  AUA Symptom Index QUESTIONS TO BE ANSWERED NOT AT ALL Over the past month, how often have you had a sensation of not emptying your bladder completely after you finished urinating? 0+ Over the past month, how often have you had to urinate again less than 2 h after you finished urinating? Over the past month, how often have you found you stopped and started again several times when you urinated? Over the past month, how often have you found it difficult to postpone urination? Over the past month, how often have you had a weak urinary stream? Over the past month, how often have you had to push or strain to begin urination? Over the past month, how many times did you most typically get up to urinate from the time you went to bed at night until the time you got up in the morning? (None) (1 time) (2 times) (3 times) (4 times) (5 times) Sum of 7 circled numbers (AUA Symptom Score): ____ Abbreviation: AUA, American Urological Association. Source: Modified with permission from MJ Barry et al: The American Urological Association symptom index for benign prostatic hyperplasia. The Measurement Committee of the American Urological Association. J Urol 148:1549, 1992. collapse secondary to bone loss are common. Neurologic symptoms, including those suggestive of base of skull disease or spinal cord compromise, require emergency evaluation because loss of function may be permanent if not addressed quickly. Neurologic symptoms and loss of function are best treated with external beam radiation, as are single sites of pain. Diffuse symptoms in the absence of neu­ rologic deficits can be treated with bone-seeking radioisotopes, such as radium-223 or the β emitter 153Sm–ethylene-diamine-tetrameth­ ylene-phosphonic acid (EDTMP); mitoxantrone; or other systemic therapies. Radium-223 is indicated for patients with symptoms and has been shown to prolong survival, whereas 153Sm-EDTMP and mitoxantrone are approved for the palliation of pain but have not been shown to prolong life. Abiraterone, enzalutamide, docetaxel, cabazitaxel, and Lu-177 PSMA-617 do not have a formal indication for pain but were shown to palliate pain in the registration trials that led to their approval by showing a survival benefit. Other bone-targeting agents, including bisphosphonates such as zoledronic acid and the RANK-ligand inhibitor denosumab, have been shown to reduce the frequency and development of skeletal complications including pain requiring analgesia, neurologic com­ promise from epidural extension of tumor, and/or the need for surgery or radiation therapy to treat symptomatic osseous disease. It is important to note that, for all of these agents, the direct effects on the tumor are limited and benefits are seen without declines in PSA or improvements on imaging. CHAPTER 92 BENIGN DISEASE Benign and Malignant Diseases of the Prostate ■ ■BENIGN PROSTATIC HYPERPLASIA BPH is a pathologic process that contributes to the development of lower urinary tract symptoms (LUTS) in patients. LUTS, arising from lower urinary tract dysfunction, are further subdivided into obstruc­ tive symptoms (urinary hesitancy, straining, weak stream, terminal dribbling, prolonged voiding, incomplete emptying) and irritative symptoms (urinary frequency, urgency, urge incontinence, small voided volumes). LUTS and other sequelae of BPH are not just due to a mass effect but are also likely due to a combination of the prostatic enlargement and age-related detrusor dysfunction. Diagnostic Procedures and Treatment  LUTS are generally measured using a validated, reproducible index that is designed to determine disease severity and response to therapy—the AUA’s Symp­ tom Index (AUASI), also adopted as the International Prostate Symp­ tom Score (IPSS) (Table 92-2). Serial AUASI is particularly useful in AUA SYMPTOM SCORE (CIRCLE 1 NUMBER ON EACH LINE) LESS THAN 1 TIME IN 5 LESS THAN HALF THE TIME ABOUT HALF THE TIME MORE THAN HALF THE TIME ALMOST ALWAYS # 22 - 93 Testicular Cancer ### 93 Testicular Cancer following patients as they are treated with various forms of therapy. Asymptomatic patients do not require treatment regardless of the size of the gland, while those with an inability to urinate, gross hematuria, recurrent infection, or bladder stones require evaluation and treat­ ment. In patients with symptoms, uroflowmetry can identify those with normal flow rates who are unlikely to benefit from treatment, and bladder ultrasound can identify those with high postvoid residuals who may need intervention. Pressure-flow (urodynamic) studies detect pri­ mary bladder dysfunction. Cystoscopy is recommended if hematuria is documented and to assess the urinary outflow tract before surgery. Imaging of the upper tracts is advised for patients with hematuria, a history of calculi, or prior urinary tract problems. Symptomatic relief is the most common reason patients seek treat­ ment for BPH, and therefore, symptomatic relief is usually the goal of therapy for BPH. α-Adrenergic receptor antagonists are thought to treat the dynamic aspect of BPH by reducing sympathetic tone of the blad­ der outlet, thereby decreasing resistance and improving urinary flow. 5ARIs are thought to treat the static aspect of BPH by reducing prostate volume and having a similar, albeit delayed effect. 5ARIs have also proven beneficial in the prevention of BPH progression, as measured by prostate volume, the risk of developing acute urinary retention, and the risk of having BPH-related surgery. The use of an alpha-adrenergic receptor antagonist and a 5ARI as combination therapy seeks to provide symptomatic relief while preventing progression of BPH. PART 4 Oncology and Hematology Another class of medications that has shown improvement in LUTS secondary to BPH is phosphodiesterase-5 (PDE5) inhibitors, used currently in the treatment of erectile dysfunction. All four of the PDE5 inhibitors available in the United States—sildenafil, vardenafil, tadalafil, and avanafil—appear to be effective in the treatment of LUTS secondary to BPH. The use of PDE5 inhibitors is not without con­ troversy, however, given the fact that short-acting phosphodiesterase inhibitors such as sildenafil need to be dosed separately from alpha blockers such as tamsulosin because of potential hypotensive effects. Symptoms due to BPH often coexist with symptoms due to overac­ tive bladder, and the most common pharmacologic agents for the treat­ ment of overactive bladder symptoms are anticholinergics. This has led to multiple studies evaluating the efficacy of anticholinergics for the treatment of LUTS secondary to BPH. Surgical therapy is now considered second-line therapy and is usu­ ally reserved for patients after a trial of medical therapy. The goal of surgical therapy is to reduce the size of the prostate, effectively reduc­ ing resistance to urine flow. Surgical approaches include TURP, trans­ urethral incision, or removal of the gland via a retropubic, suprapubic, or perineal approach. Also used are transurethral ultrasound–guided laser-induced prostatectomy (TULIP), stents, and hyperthermia. ■ ■FURTHER READING Bergengren O et al: 2022 Update on prostate cancer epidemiology and risk factors: A systematic review. Eur Urol 84:191, 2023. Deek MP et al: Multi-institutional analysis of metastasis-directed ther­ apy with or without androgen deprivation therapy in oligometastatic castration-sensitive prostate cancer. Eur Urol Oncol 7:1403, 2024. Donovan JL et al: Patient-reported outcomes 12 years after localized prostate cancer treatment. NEJM Evid 2:EVIDoa2300018, 2023. Erra­ tum in: NEJM Evid 2:EVIDx2300122, 2023. Eastham JA et al: Clinically localized prostate cancer: AUA/ASTRO Guideline. J Urol 208:505, 2022. Fendler WP et al: Assessment of 68Ga-PSMA-11 PET accuracy in localizing recurrent prostate cancer: A prospective single-arm clinical trial. JAMA Oncol 5:856, 2019. Haile ES et al: Medical management of benign prostatic hyperplasia. Cleve Clin J Med 91:163, 2024. Hamdy FC et al: Fifteen-year outcomes after monitoring, surgery, or radiotherapy for prostate cancer. N Engl J Med 388:1547, 2023. Hugosson J et al: Prostate cancer screening with PSA and MRI fol­ lowed by targeted biopsy only. N Engl J Med 387:2126, 2022. Hussain M et al: Survival with olaparib in metastatic castration- resistant prostate cancer. N Engl J Med 383:2345, 2020. Kasivisvanathan V et al: MRI-targeted or standard biopsy for prostate-cancer diagnosis. N Engl J Med 378:1767, 2018. Merseburger AS et al: Genomic testing in patients with metastatic castration-resistant prostate vancer: A pragmatic guide for clinicians. Eur Urol 79:519, 2021. Morgan TM et al: Salvage therapy for prostate cancer: AUA/ASTRO/ SUO guideline part I: Introduction and treatment decision-making at the time of suspected biochemical recurrence after radical prostatec­ tomy. J Urol 211:509, 2024. Pinsky PF, Parnes H: Screening for prostate cancer. N Engl J Med 388:1405, 2023. Roach M 3rd et al: Prostate cancer, race, and health disparity: What we know. Cancer J 29:328, 2023. Sartor O et al: Lutetium-177-PSMA-617 for metastatic castrationresistant prostate cancer. N Engl J Med 385:1091, 2021. Virgo KS et al: Initial management of noncastrate advanced, recurrent, or metastatic prostate cancer: ASCO guideline update. J Clin Oncol 39:1274, 2021. David J. Vaughn Testicular Cancer Testicular germ cell tumors (GCTs) represent 95% of all testicular neo­ plasms. Non-GCTs of the testis are much less common. Approximately 5% of GCTs arise in extragonadal locations including the mediastinum, retroperitoneum, and pineal gland. Treatment for testicular GCTs is determined by pathology and stage. The development of effective chemotherapy for this disease represents a landmark achievement in oncology. About 95% of newly diagnosed patients with testicular GCTs will be cured. For this reason, testicular cancer has been called “a model for a curable neoplasm.” INCIDENCE AND GLOBAL CONSIDERATIONS In 2023, ∼9200 cases of testicular GCTs will be diagnosed in the United States, with 470 deaths. The incidence of testicular GCTs appears to be increasing worldwide. The disease has the highest incidence in Scandinavia, Western Europe, and Australia/New Zealand. Africa and Asia have the lowest incidence. The incidence in the United States and the United Kingdom is intermediate. While a distinct biology related to geography is not apparent, several countries have reported a migration to earlier stage disease in part related to public awareness and earlier diagnosis. ■ ■EPIDEMIOLOGY Testicular GCT is the most common malignancy diagnosed in adoles­ cent and young adult males (defined as age 15–39 years). The incidence in patients over 50 is increasing. Testicular GCT is most commonly diagnosed in Caucasians. The disease is much less commonly seen in African Americans. Testicular GCTs have an estimated heritability of almost 50%. Interestingly, the risk of GCT is higher in male siblings than in offspring of the patient. Although epidemiologic studies have been performed attempting to identify a relationship with environmental exposures, no conclusive causal links have been established. Risk Factors  The strongest risk factors for testicular GCT include a prior history of the disease, cryptorchidism, and a history of testicular germ cell neoplasia in situ. Patients with a prior history of testicular GCT have a 1–2% risk of developing a contralateral GCT. These are more commonly metachronous than synchronous. Men with crypt­ orchidism have approximately a four- to sixfold increased risk of developing testicular GCT. Orchidopexy before puberty decreases but does not eliminate this risk. Interestingly, the contralateral descended testis is also at risk for this disease. Men undergoing infertility evalu­ ation in which a testicular biopsy demonstrates germ cell neoplasia in situ have a significant risk of developing GCT. Although scrotal ultrasound of patients with testicular GCT may demonstrate testicular microcalcifications that may be related to germ cell neoplasia in situ, the significance of testicular microcalcifications in the general popula­ tion is unclear. ■ ■BIOLOGY The primordial germ cell is the cell of origin for GCTs. Most malignant GCTs arise from in situ neoplasia. The molecular events that result in the development of germ cell neoplasia in situ and subsequent malig­ nant GCT have not been fully determined. However, genetic analysis of GCTs has demonstrated an excess copy number of isochromosome 12p (i[12p]) in most cases. Several genome-wide association studies have identified multiple independent loci associated with testicular GCT risk. The strongest of these is the KITLG (KIT ligand) locus on chromosome 12. These loci contribute significantly to the heritable risk of this disease. ■ ■PATHOLOGY GCTs are either seminomas or nonseminomas. For a tumor to be considered a seminoma, it must be 100% seminoma. Any mixed GCT should be approached as a nonseminomatous GCT. Seminomas repre­ sent ∼50% of cases. Seminomas arise most commonly in patients in the fourth decade of life. Seminomas may contain syncytiotrophoblastic cells, which may secrete β-human chorionic gonadotropin (hCG). Seminomas do not secrete α-fetoprotein (AFP). Seminomas are exqui­ sitely sensitive to both chemotherapy and radiation therapy. Nonsemi­ nomatous GCTs are most commonly diagnosed in the third decade of life. The histologic subtypes include embryonal carcinoma, yolk sac tumor, choriocarcinoma, and teratoma. Embryonal carcinoma is the most undifferentiated nonseminomatous GCT subtype with the poten­ tial to differentiate into the other subtypes. Embryonal carcinoma may secrete AFP, hCG, both, or neither. Yolk sac tumor often secretes AFP. Choriocarcinoma is an aggressive subtype, often secreting hCG at very high levels. These nonseminomatous GCT subtypes are all considered chemotherapy sensitive. Teratoma is composed of somatic cell types that are derived from two or more germinal layers (endoderm, meso­ derm, and ectoderm). Teratomas are classified as mature, in which cell types resemble normal adult somatic tissue; immature, in which cell types resemble fetal somatic tissue; and malignant, in which the cell types have undergone malignant transformation into the malignant counterpart of the somatic tissue. Teratomas are chemotherapy resis­ tant and must be treated surgically. ■ ■INITIAL PRESENTATION Signs and Symptoms  Although a painless testicular mass is pathognomonic of a GCT, most patients present with testicular swell­ ing, firmness, discomfort, or a combination of these. The differential diagnosis may include epididymitis or orchitis, and a trial of antibacte­ rials may be considered. Patients with retroperitoneal metastases may complain of back or flank pain. Patients may have cough, shortness of breath, or hemoptysis because of lung metastases. In patients with elevation of serum hCG, gynecomastia may be present. Diagnostic delay is not uncommon and may be associated with a more advanced stage at diagnosis. Physical Examination  Careful examination of the affected testis and the contralateral normal testis should be performed. Many tumors will have a hard consistency to palpation. Some patients may show testicular atrophy. Evaluation for supraclavicular lymphadenopathy, gynecomastia, and abdominal mass should be performed. Inguinal lymphadenopathy is rare. Most patients with lung metastases will have normal auscultation of the lungs. Diagnostic Testing  If a firm testicular mass is identified, a scrotal ultrasound should be performed. Patients with suspected epididymitis or orchitis who do not respond to antibiotics should also undergo scrotal ultrasound. Scrotal ultrasound should include both testicles. On ultrasound, a testicular GCT is hypoechoic and may be multifocal. A solid mass identified on ultrasound should be considered malignant until otherwise proven. Transscrotal aspiration or biopsy of a testicular mass should never be performed. Such scrotal violation may result in tumor seeding of the scrotum or inguinal lymph nodes. Serum Tumor Markers  Serum AFP, hCG, and lactate dehydro­ genase (LDH) should be measured in patients suspected of testicular GCT. AFP is elevated in ∼60–70% of patients who present with non­ seminomatous GCTs. Seminomas never secrete AFP. A patient with a seminoma with elevation of AFP should be approached as having a nonseminomatous GCT. The half-life of AFP is 5–7 days. A falsely elevated AFP may be seen in patients with hepatic disease or a condi­ tion called hereditary persistence of AFP, in which patients may have baseline AFP levels that are mildly elevated. hCG may be elevated in both nonseminomatous GCTs as well as seminomas. Patients with cho­ riocarcinoma may have markedly elevated levels of hCG. The half-life for hCG is 24–36 h. False-positive elevation of hCG may be seen sec­ ondary to hypogonadism, marijuana use, or because of interfering sub­ stances measured by the assay. LDH is a nonspecific marker for GCT. Its principal use is to help in the assessment of the risk classification of a patient with metastatic disease. Although elevation of serum tumor markers supports the diagnosis of a testicular GCT, most patients with seminoma and up to a third of patients with nonseminomatous GCTs do not have elevated levels. Serum microRNA (miR)-371a-3 has been identified as a promising biomarker for GCT, and validation studies are ongoing. CHAPTER 93 Testicular Cancer ■ ■INITIAL MANAGEMENT Inguinal Orchiectomy  Prompt referral to urology should be performed if a testicular GCT is suspected. The initial treatment for most patients suspected of having a testicular GCT is radical ingui­ nal orchiectomy with removal of the testicle and spermatic cord to the level of the internal inguinal ring. In patients who present with metastatic disease and the diagnosis of GCT is certain, orchiectomy may be deferred until completion of chemotherapy. Although some institutions perform testis-sparing surgery in select patients, the gold standard remains radical inguinal orchiectomy. Pathologic examina­ tion of the entire testicle is important, since testicular GCTs may be multifocal. Given the rarity of this cancer, review by an experienced pathologist is essential for accurate tumor classification. Serum tumor markers should be obtained before and after orchiectomy. Staging  The staging of testicular GCT is based on an understanding of the pattern of spread. The initial spread is by the lymphatic route to the retroperitoneal lymph nodes. A left-sided testicular GCT spreads first to the primary landing zone of left paraaortic lymph nodes inferior to the left renal vessels. A right-sided testicular GCT spreads first to the primary landing zone of the aortocaval nodes inferior to the right renal vessels. Nodal metastases may extend into the iliac regions. If scrotal violation occurred, inguinal lymph node metastases may be seen. Subsequent lymphatic spread is to the retrocrural, mediastinal, and supraclavicular lymph nodes. Hematogenous spread to the lung is the next most com­ mon site of metastasis. Metastases to the liver, bone, and brain are less common. Patients with newly diagnosed testicular GCTs should undergo computed tomography (CT) scan of the abdomen and pelvis. Chest x-ray should be performed. CT scan of the chest is performed if retroperitoneal metastases are present or if lung nodules are identified on chest x-ray. Bone scan and magnetic resonance imaging (MRI) of the brain are not routinely performed unless clinically indicated. Positron emission tomography (PET) has little role in the initial staging of testicular GCTs. The American Joint Committee on Cancer tumor-node-metastasis (TNM) staging classification is used. There are three main stages of testicular GCT. Stage I is limited to the testis; stage II involves the ret­ roperitoneal lymph nodes; and stage III includes lymph node involve­ ment beyond the retroperitoneum and/or distant metastatic disease. ■ ■STAGE-BASED MANAGEMENT Treatment of testicular GCT is based on two factors: (1) whether the tumor is seminoma or nonseminomatous GCT and (2) the stage of the patient. This is summarized in Fig. 93-1. Stage I  •  SEMINOMA  About 70% of newly diagnosed patients with seminoma present with stage I disease. This is defined as no evidence of metastatic disease on imaging of the chest, abdomen, and pelvis. Approximately 15% of patients with stage I seminoma have metastatic disease at the microscopic level, usually in the retroperito­ neum. Historically, patients with stage I seminoma were treated with a course of adjuvant radiation therapy to the paraaortic lymph nodes. While still an option, this is not usually performed because of concerns for late radiation-induced secondary malignancies. Active surveillance is the most common approach elected by these patients following orchiectomy. With active surveillance, interval physical examination and CT scan of the abdomen are performed. For the 15% of patients who develop metastatic disease during active surveillance, treatment is curative in nearly all. A third option for clinical stage I seminoma is adjuvant chemotherapy with carboplatin monotherapy for one or two cycles. While effective in decreasing the risk of recurrence, most patients are cured by orchiectomy alone, and therefore, the additional treatment is unnecessary. In addition, long-term data on toxicity are not available. PART 4 Oncology and Hematology NONSEMINOMATOUS GCTS  About 40% of newly diagnosed patients with nonseminomatous GCTs present with stage I disease. Because nonseminomatous GCTs have an increased potential for invasion and metastasis, spread to the retroperitoneum and beyond is more com­ mon than with seminoma. If pre-orchiectomy serum tumor markers are elevated, these must normalize after orchiectomy to be considered stage I. Patients with persistently elevated or rising serum tumor mark­ ers after orchiectomy have stage IS disease and should be treated with cisplatin-based chemotherapy. If the tumor is limited to testis without lymphovascular invasion, the risk of recurrence is approximately 20%. However, if the tumor has high-risk features including lymphovascular invasion, invasion of the spermatic cord, or invasion of the scrotum, the risk of recurrence is ∼50% or higher. Historically, a prophylactic retroperitoneal lymph node dissection (RPLND) was performed. This surgery is not only diagnostic but also therapeutic. In fact, most patients who undergo prophylactic RPLND will never require chemo­ therapy. While still an option, this approach subjects many patients to unnecessary major abdominal surgery. RPLND is also associated with a small risk of retrograde ejaculation due to nerve injury, and nerve-sparing techniques have been developed. Active surveillance is frequently performed especially for patients without lymphovascular invasion. Most patients who relapse will be treated with cisplatin-based chemotherapy and achieve cure rates approaching 100%. Active sur­ veillance can also be employed for patients with higher risk features, although the risk of progression is significantly higher. For this rea­ son, some advocate adjuvant cisplatin-based chemotherapy with BEP (bleomycin, etoposide, cisplatin) for one cycle for these patients. Other centers favor a prophylactic RPLND. Almost all patients who present with stage I nonseminomatous GCTs will achieve cure. Stage II  •  SEMINOMA  Approximately 15–20% of newly diag­ nosed patients with seminoma present with stage II disease. Patients are subgrouped into IIA, IIB, or IIC based on the size of the retroperi­ toneal nodes (≤2 cm, >2 to 5 cm, or >5 cm, respectively). Patients with stage IIA disease are usually treated with “dogleg” radiation therapy (referring to the shape of the radiation field), which includes the para­ aortic and ipsilateral iliac nodes. Cisplatin-based chemotherapy may also be considered. Stage IIB disease is treated with cisplatin-based chemotherapy or, in select patients, radiation therapy. Most patients treated with radiation therapy who relapse will subsequently be cured with cisplatin-based chemotherapy. RPLND has been considered in select patients with stage IIA and nonbulky stage IIB seminoma in an effort to avoid chemotherapy and radiation therapy. For patients with stage IIC disease, cisplatin-based chemotherapy should be used. NSGCTS  Approximately 15% of newly diagnosed patients with non­ seminomatous GCTs present with clinical stage II disease. Patients with stage IIA disease may be treated with primary RPLND. Alternatively, these patients may be treated with cisplatin-based chemotherapy. Patients with stage IIB and IIC disease are best initially managed with cisplatin-based chemotherapy. Stage III  Patients who present with stage III GCT (seminoma or nonseminomatous GCT) are treated with cisplatin-based chemother­ apy. These patients are classified into good-, intermediate-, or poor-risk categories using the International Germ Cell Consensus Classification system, which is based on clinical factors including histology, site of primary, the presence of nonpulmonary visceral metastatic disease, and the level of postorchiectomy serum tumor markers (Table 93-1). Most patients with stage III GCT present with good-risk disease and >90% will be cured. The remainder present with intermediate-risk or poor-risk disease associated with 5-year survival rates of ∼80% and 50%, respectively. Select patients with rapidly progressive metastatic disease and life-threatening symptoms such as hemoptysis in whom there is a high clinical suspicion of GCT should emergently initiate cisplatin-based chemotherapy, even without a tissue diagnosis. Chemotherapy  The development of cisplatin-based chemotherapy represents an important advance in cancer medicine. Through a series of carefully performed clinical trials with the aim of maximizing cure while minimizing the extent of treatment, the chemotherapy approach to the treatment of these patients has been standardized. Patients with good-risk metastatic GCT are treated with either three cycles of BEP or four cycles of etoposide and cisplatin (EP). Patients with intermediate- and poor-risk metastatic disease are treated with either four cycles of BEP or four cycles of etoposide, ifosfamide, and cisplatin (VIP). Maintain­ ing dose and schedule is important, as dose modifications and delays have been associated with inferior outcomes. Serum tumor markers should be monitored throughout treatment and should normalize during or after treatment. Cisplatin-based chemotherapy is associated with myelosuppression, nausea and vomiting, and alopecia. Cisplatin may result in nephrotoxicity, ototoxicity, and peripheral neuropathy. Bleomycin may result in pulmonary toxicity, and risk factors for this include age >40, renal failure, tobacco use, and the cumulative dose of bleomycin received. For patients at increased risk of bleomycininduced pneumonitis, non–bleomycin-containing regimens as noted above may be given. Cisplatin-based chemotherapy is also associated with sterility. Approximately 30% of newly diagnosed testicular GCT patients have severe oligospermia or azoospermia. For the remainder with normal baseline spermatogenesis who receive cisplatin-based chemotherapy, all will be azoospermic at the completion of therapy. Approximately 80% of these patients will recover spermatogenesis over a period of several years. For this reason, prechemotherapy sperm banking should be offered to all patients treated with chemotherapy. Postchemotherapy Surgery  Upon completion of cisplatin-based chemotherapy, many patients with normalized serum tumor markers will have radiographic evidence of residual masses. In approximately half of patients with nonseminomatous GCT, the residual mass is composed of necrosis and/or fibrosis. About 40% will have residual teratoma, and only 10% will have residual viable nonteratomatous GCT. Unfortunately, radiographic imaging cannot accurately differen­ tiate between these entities. For this reason, nonseminomatous GCT patients with residual masses after chemotherapy undergo resection of all sites of disease. This most commonly includes a postchemotherapy RPLND. However, thoracotomy and neck dissection are required in some patients. Given the complexity of this surgery, patients should be referred to highly experienced centers. If the patients are found to have residual necrosis or teratoma, no additional therapy is required. Testis Seminoma NSGCT Stage IA Testis only, no lymphovascular invasion Active surveillance; or Adjuvant carboplatin × 1 or 2 cycles; or Adjuvant para-aortic RT Stage IB Testis only, with lymphovascular invasion or invasion of spermatic cord or scrotum Active surveillance; or Adjuvant carboplatin × 1 or 2 cycles; or Adjuvant para-aortic RT Stage IS Elevated serum tumor markers postorchiectomy BEP × 3 cycles; or EP × 4 cycles BEP × 3 cycles; or EP × 4 cycles A Lymph nodes Seminoma NSGCT Stage IIA N1: nodes ≤ 2 cm Para-aortic and ipsilateral iliac RT; or BEP × 3 cycles or EP × 4 cycles; Nerve-sparing RPLND in select patients Stage IIB N2: nodes > 2 to 5 cm BEP × 3 cycles or EP × 4 cycles; or Para-aortic and ipsilateral iliac RT BEP × 3 cycles or EP × 4 cycles +/– postchemotherapy RPLND Stage IIC N3: nodes > 5 cm BEP × 3 cycles or EP × 4 cycles BEP × 3 cycles or EP × 4 cycles +/– postchemotherapy RPLND B FIGURE 93-1  Stage-based management of testicular germ cell tumor. Stage 1 CHAPTER 93 Active surveillance; or Nerve-sparing RPLND; or Adjuvant BEP × 1 cycle Active surveillance; or Adjuvant BEP × 1 cycle; or Nerve-sparing RPLND Testicular Cancer Stage 2 Testis Nerve-sparing RPLND; or BEP × 3 cycles or EP × 4 cycles Stage 3 Lungs Liver Lymph nodes Testis PART 4 Oncology and Hematology Seminoma NSGCT Stage IIIA (good-risk) BEP × 3 cycles; or EP × 4 cycles BEP × 3 cycles; or EP × 4 cycles; +/– Postchemotherapy surgery Stage IIIB (intermediate-risk) BEP × 4 cycles; or VIP × 4 cycles BEP × 4 cycles; or VIP × 4 cycles +/– Postchemotherapy surgery Stage IIIC (poor-risk) N/A BEP × 4 cycles; or VIP × 4 cycles +/– Postchemotherapy surgery Abbreviations: BEP, bleomycin, etoposide, cisplatin; EP, etoposide, cisplatin; N/A, not applicable; NSGCT, nonseminomatous germ cell tumor; RPLND, retroperitoneal lymph node dissection; RT, radiation therapy; VIP, etoposide, ifosfamide, cisplatin. C FIGURE 93-1  (Continued) TABLE 93-1  International Germ Cell Consensus Classification System RISK GROUP SEMINOMA NSGCT Good Any primary site; and normal AFP, any hCG, any LDH; and nonpulmonary visceral metastases absent Gonadal or retroperitoneal primary; and nonpulmonary visceral metastases absent; and AFP <1000 ng/mL; and hCG <5000 mIU/mL; and LDH <1.5 × ULN Intermediate Any primary site; and normal AFP, any hCG, any LDH; and nonpulmonary visceral metastases present Gonadal or retroperitoneal primary; and nonpulmonary visceral metastases absent; and one of the following: AFP 1000–10,000 ng/mL HCG 5000–50,000 mIU/mL LDH 1.5–10 × ULN Poor N/A Mediastinal primary; or nonpulmonary visceral metastases present; or one of the following: AFP >10,000 ng/mL HCG >50,000 mIU/mL LDH >10 × ULN Abbreviations: AFP, α-fetoprotein; hCG, human chorionic gonadotropin; LDH, lactate dehydrogenase; N/A, not applicable; NSGCT, nonseminomatous germ cell tumor; ULN, upper limit normal. Nonpulmonary visceral metastases include liver, bone, and brain. Source: Reproduced with permission from International Germ Cell Cancer Collaborative Group: International Germ-Cell Consensus Classification: A prognostic factor based staging system for metastatic germ cell tumors. J Clin Oncol 15:594, 1997. Brain Bone However, for patients with residual viable nonteratomatous GCT, two additional cycles of chemotherapy may be considered. It should be noted that in most centers, patients with minimal residual tumors defined as retroperitoneal lymph nodes of ≤1 cm forego postchemo­ therapy RPLND. Patients who experience normalization of serum tumor markers with first-line chemotherapy but have enlarging tumors, most often cystic masses in the retroperitoneum, may have “growing teratoma syndrome.” These patients are best approached with surgery. For patients with metastatic seminoma, most residual masses are necrotic and do not harbor viable tumor. Patients with residual masses of 3 cm or less may be observed without surgery. For patients with residual masses >3 cm, fluorodeoxyglucose (FDG)-PET may be used to distinguish necrosis from viable seminoma and identify patients who should be considered for postchemotherapy surgery or short interval imaging. ■ ■RELAPSED DISEASE Approximately 20–30% of patients with metastatic GCTs treated with cisplatin-based chemotherapy will not achieve durable disease control. Most of these patients will experience disease progression within 2 years following completion of chemotherapy. The International Prognostic Factors Study Group developed a risk stratification classification sys­ tem for patients in first relapse. Contributors to a worsened prognosis include NSGCT histology, extragonadal primary, incomplete response to first-line chemotherapy, time to relapse of 3 months or less, level of serum tumor markers at relapse, and the presence of nonpulmonary visceral metastatic disease. # 23 - 94 Gynecologic Malignancies ### 94 Gynecologic Malignancies Patients in first relapse may be treated with either conventionaldose salvage chemotherapy or high-dose salvage chemotherapy with autologous stem cell rescue. There is controversy concerning which approach is optimal. Some institutions advocate for risk stratification, with more favorable prognosis patients receiving conventional-dose chemotherapy and worse prognosis patients receiving high-dose che­ motherapy. The most commonly utilized conventional-dose regimen includes paclitaxel, ifosfamide, and cisplatin (TIP). High-dose chemo­ therapy consists of initial salvage therapy followed by stem cell harvest and then two or three cycles of high-dose carboplatin and etoposide (CE) with stem cell rescue. A large retrospective analysis has com­ pared conventional-dose salvage chemotherapy to high-dose salvage chemotherapy in patients in first relapse. This study reports a more favorable outcome with high-dose salvage chemotherapy across nearly all risk groups. However, given the retrospective nature of this study and the controversy concerning optimal approaches, an international randomized trial comparing conventional-dose chemotherapy (TIP) to high-dose chemotherapy with autologous stem cell rescue (TI-CE) has completed accrual and results are forthcoming. Some patients who experience disease progression after conven­ tional-dose salvage chemotherapy may successfully be treated with high-dose salvage chemotherapy with autologous stem cell rescue. Patients with disease progression after high-dose salvage chemo­ therapy may be treated with subsequent chemotherapy regimens that include gemcitabine/oxaliplatin, gemcitabine/paclitaxel, epirubicin/ cisplatin, and oral etoposide. While these patients may benefit from third-line chemotherapy, few will achieve durable disease control. Select patients with relapsed but resectable disease may be candidates for salvage or so-called “desperation” surgery. Studies of molecularly targeted agents and immune checkpoint inhibitors in this population have to date been generally disappointing. Patients who experience disease progression >2 years after chemo­ therapy are considered to have “late relapse.” Late relapse appears to have a different biology than early relapse. These patients tend to have more chemotherapy-resistant disease. Patients with late relapse usu­ ally have nonseminomatous GCT with elevation of serum AFP. Many of these patients experience recurrence in the retroperitoneum many years after first-line chemotherapy, and this likely represents residual retroperitoneal disease that was not controlled after first-line therapy. These patients are best approached with salvage surgery. ■ ■EXTRAGONADAL GERM CELL TUMORS Approximately 5% of patients who present with GCTs have extrago­ nadal primaries. These mainly originate in the mediastinum or retro­ peritoneum. Patients suspected of extragonadal GCT should undergo scrotal ultrasound to exclude a gonadal primary. Extragonadal semi­ nomas have a similar excellent prognosis as their gonadal counterparts and are approached the same. Mediastinal nonseminomatous GCTs are classified as poor risk and are treated with either four cycles of BEP or four cycles of VIP. These patients frequently require postchemotherapy thoracic surgery for residual disease. For this reason, some advocate avoiding bleomycin in this patient population. Klinefelter’s syndrome is associated with an increased risk of mediastinal nonseminomatous GCTs. Rarely, mediastinal nonseminomatous GCTs are associated with hematologic disorders including acute myeloid leukemia. Nonsemi­ nomatous GCTs arising in the retroperitoneum do not have a worse prognosis than their gonadal counterparts. Many patients who present with extragonadal GCTs will undergo core needle biopsy for diagno­ sis. However, select patients with extragonadal tumors and definitive elevation of serum tumor markers may initiate chemotherapy without a tissue diagnosis. Cancers of unknown primary are defined as histologically proven metastatic malignancy in which the primary site is not obvious. A subgroup of patients with cancer of unknown primary have occult GCTs. Male gender, age <65 years, midline tumors, and nonsmok­ ing status increase the likelihood of this presentation. Pathology may demonstrate a poorly differentiated malignant neoplasm. Immunohis­ tochemical staining is used to exclude lymphoma. Tumor may be ana­ lyzed by fluorescence in situ hybridization for i(12p), which confirms the diagnosis. Even if the diagnosis is not certain, patients should be treated with cisplatin-based chemotherapy, which will cure up to 20% of this patient group. ■ ■TESTICULAR NON–GERM CELL TUMORS Rarely, patients may develop testicular non-GCTs. These include nonHodgkin’s lymphoma, most commonly occurring in men over the age of 50; sex cord stromal tumors including Leydig cell tumors and Sertoli cell tumors; mesothelioma of the tunica vaginalis; and paratesticular sarcoma. Metastasis to the testis is rare, most commonly occurring in patients with advanced prostate cancer and melanoma. ■ ■SURVIVORSHIP AND LATE EFFECTS Because most patients with testicular GCT will experience long-term survival, survivorship care is important. Since primary care physicians will follow many of these patients, an understanding of the physical, psychological, and social late effects is important. Late effects are defined as health problems that occur months or years after a disease is diagnosed or after treatment has ended. Late effects may be related to the underlying cancer or to the treatment the patient received. In longterm survivors of testicular GCT, increased cardiovascular risk and increased secondary malignancies have been reported. Patients treated with cisplatin-based chemotherapy have an increased risk of hyperten­ sion, hyperlipidemia, metabolic syndrome, and cardiovascular events. Patients treated with high cumulative doses of etoposide (e.g., patients who receive standard chemotherapy, relapse, and then receive salvage high-dose chemotherapy) may experience up to a 1–2% risk of devel­ oping acute myeloid leukemia, typically 2–3 years after completing therapy and associated with an 11q23 translocation. Patients treated with radiation therapy, cisplatin-based chemotherapy, or both have an increased risk of developing secondary solid malignancies. CHAPTER 94 Gynecologic Malignancies ■ ■FURTHER READING King J et al: Testicular cancer: Biology to bedside. Cancer Res 81:5369, 2021. Lobo J et al: Molecular biomarkers with potential clinical application in testicular cancer. Mod Pathol 36:100307, 2023. Pluta J et al: Identification of 22 novel susceptibility loci associated with testicular germ cell tumors. Nat Commun 12:4487, 2021. Travis LB et al: Adolescent and young adult germ cell tumors: Epi­ demiology, genomics, treatment, and survivorship. J Clin Oncol 42:696-706, 2024. David Spriggs Gynecologic Malignancies OVARIAN CANCER ■ ■INCIDENCE AND PATHOLOGY Ovarian cancer remains a leading cause of cancer deaths in American women, ranking behind lung, breast, colon, and pancreatic cancers. The ovary is responsible for hormone production and egg produc­ tion, including maturation and ovulation with the supporting cyclical production of sex steroid hormones. These complex biologic func­ tions are linked to populations of stromal cells, ovarian germ cells, and the enveloping epithelial cells. Malignancies arising from each group include multiple histologic variants, each with unique neoplastic behaviors. Epithelial tumors are, by far, the most common histologic variant of ovarian neoplasms; they may be benign (50%), frankly malignant (33%), or of borderline malignancy (low malignant poten­ tial) (16%). In adnexal masses detected by imaging or physical exam, age influences risk of malignancy; tumors in younger women are more likely benign. In the malignant group, the most common tumors are epithelial. In the group of the ovarian epithelial malignancies are the serous tumors (60–70%), mucinous tumors (10%), endometrioid tumors (10–15%), and clear cell tumors (10–15%) tumors. The dis­ tribution of histologic types varies in different parts of the world. The less common stromal tumors arise from the ancillary, supportive cells such as steroid hormone–producing cells and likewise have different phenotypes and clinical presentations. Most stromal tumors do not produce estrogen, but ectopic hormone production can be seen in certain subtypes. Tumors arising in the ovarian germ cell lineage are generally similar in biology and behavior to testicular tumors in males, although their intraperitoneal location alters some metastatic behaviors (Chap. 93). Ovarian tissue may also host metastatic epithelial tumors arising from breast, colon, gastric, and pancreatic primaries. Bilateral ovarian masses from metastatic mucin-secreting gastrointestinal can­ cers are termed Krukenberg tumors. Consideration of other potential malignancies is part of the diagnostic workup of ovarian masses. ■ ■OVARIAN CANCER OF EPITHELIAL ORIGIN Epidemiology  An American woman has approximately a 1 in 72 lifetime risk (1.6%) of developing ovarian cancer, with the majority of affected women developing epithelial tumors. In 2024 in the United States, ~19,710 cases of ovarian cancer are expected to be diagnosed, with >13,270 deaths. Sporadic (not familial) epithelial tumors of the ovary have a peak incidence in women in their fifties and sixties, although age at presentation ranges from the third decade to the eight­ ies and nineties. Ovarian cancer risk has been linked to an interactive mixture of epidemiologic, environmental, and genetic factors. Nul­ liparity, obesity, diet, infertility treatments, talc exposure, and possibly hormone replacement therapy have all been linked to an increase in risk. Protective factors include the use of oral contraceptives, multipar­ ity, tubal ligation, aspirin use, and breast-feeding. Other epidemiologic factors such as the historical use of perineal talc agents remain contro­ versial. The mechanisms underlying the various protective factors are largely unknown, but it is increasingly clear that dysplasia and in situ cancers are seen within the fallopian tube and probably are the original site for a large percentage of cancers. PART 4 Oncology and Hematology Genetics and Pathogenesis  Ovarian cancers are divided into type 1 cancers and the more aggressive type 2 variant. The type 1 can­ cers are characterized by low-grade histology and generally indolent behavior. These tumors include the low malignant potential tumors, low-grade endometrial and mucinous histologies, and clear cell can­ cers (which are more aggressive). Genetic alterations in type 1 cancers include mutations in KRAS, BRAF, PTEN, and PIK3CA. In contrast, type 2, high-grade serous epithelial ovarian cancers show serial genetic changes in the fallopian tube with loss of BRCA1/2 function and TP53 mutation leading to intraepithelial cancer in the luminal epithelium. Following these early genetic events, additional mutations in these transformed cells lead to tumor cell shedding, metastasis, and invasion. These type 2, poorly differentiated, serous cancer cells can then spread to the ovaries and the peritoneal cavity, aided by the ovarian cancer cell’s expression of MUC16 and binding to mesothelin-expressing cells. Genetically, type 2 serous ovarian cancer is classically a disease characterized by loss of TP53 (95%) and BRCA1/2 function in nearly all cases. Widespread amplifications and deletions rather than single-gene point mutations or common gene fusions are also present. Low preva­ lence but statistically recurrent somatic mutations in seven other genes including NF1, RB1, and CDK12 were also seen. The most common heritable abnormality linked to ovarian cancer is a germline mutation in either BRCA1 (chromosome 17q12–21) or BRCA2 (chromosome 13q12–13). These genes are essential parts of the homologous DNA repair machinery for double-stranded DNA break repair. Individuals inheriting a single copy of a mutant allele have an increased lifetime risk of breast (46–87% for BRCA1; 38–84% for BRCA2) and ovarian cancer (39–63% for BRCA1; 16.5–27% for BRCA2). Many of these women have a family history that includes multiple cases of breast and/ or ovarian cancer at an early age. Male breast cancer, pancreatic cancer, and prostate cancer are also linked to familial BRCA2 mutations. The most common malignancy in women carrying germline BRCA1/2 mutations is breast carcinoma, although women harboring germline BRCA1 mutations also have a marked increased risk of developing ovarian malignancies in their forties and fifties. Women harboring a mutation in BRCA2 have a lower penetrance of ovarian cancer with onset typically in their fifties or sixties. Other uncommon germline mutations of other genes encoding proteins linked to homologous DNA repair (e.g., PALB2) can also contribute to cancer risk, although the frequency of mutation and magnitude of risk increment are much lower. Germline BRCA1/2 testing is recommended for all incident epi­ thelial ovarian cancers to detect probands to identify relatives for early therapeutic intervention. Women with these high-risk germline muta­ tions are advised to undergo prophylactic removal of fallopian tubes and ovaries after completing childbearing, ideally before age 40. Early prophylactic salpingo-oophorectomy is highly protective. Salpingooophorectomy also appears to protect these women from subsequent breast cancer (risk reduction 50%). Prophylactic salpingectomy is almost certainly the key part of any surgical prophylaxis strategy for ovarian cancer prevention. Although less common, women with type II Lynch syndrome caused by mutations in one of the DNA mismatch repair genes (MSH2, MLH1, MLH6, PMS1, PMS2) are at risk for ovarian and endometrial cancer. Like BRCA1/2-related cancers, these cancers develop earlier than sporadic ovarian cancer. Neoplasms of the ovary tend to be painless unless they undergo torsion. Nonspecific gastrointestinal symptoms like bloating and early satiety are common at presentation, probably related to compression of local organs or due to symptoms from metastatic disease. Women with ovarian tumors also may have an increased incidence of symptoms including pelvic discomfort, bloating, and perhaps changes in urinary or bowel pattern. Unfortunately, these same symptoms are common in primary care and are frequently dismissed by either the woman or her health care team until later stages of disease. The pathogenic factors and timing of spread beyond the ovary are still not well understood. The most common symptoms at presentation of advanced disease include a period of progressive complaints of nausea, early satiety, bloating, indigestion, constipation, and abdominal pain. Signs include the rapid increase in abdominal girth due to the accumulation of ascites that typically alerts the patient and her physician that the concurrent gas­ trointestinal symptoms are likely associated with malignant pathology. Radiologic evaluation typically demonstrates a complex adnexal mass with ascites, carcinomatosis, and pelvic, para-aortic, and mesenteric adenopathy in advanced disease. Positron emission tomography (PET) scans are generally not required. Laboratory evaluation often demon­ strates a markedly elevated serum CA-125, the shed mucin component (MUC16) associated with, but not specific for, ovarian cancer. Ovarian cancers are divided into four stages, with stage I tumors confined to the ovary, stage II malignancies confined to the pelvis, and stage III con­ fined to the peritoneal cavity and retroperitoneal nodes (Table 94-1). These three stages are subdivided, with the most common presenta­ tion, stage IIIC, defined as tumors with bulky intraperitoneal disease or positive lymph node involvement. About 70% of women present with stage III disease. Stage IV disease includes women with parenchymal metastases (liver, lung, spleen) or, alternatively, abdominal wall or pleu­ ral disease. The 30% of patients not presenting with stage III disease are roughly evenly distributed among the other stages. Screening  Advanced ovarian cancer is a highly lethal condition. It is curable in early stages but seldom curable in advanced stages; hence, screening continues to be of considerable interest. Early-stage tumors often secrete excessive amounts of normal proteins that can be measured in the serum such as CA-125, mesothelin, and HE-4. Never­ theless, the incidence of ovarian cancer in the middle-aged female pop­ ulation is very low, with only ~1 in 2000 women between the ages of 50 and 60 carrying an asymptomatic and undetected tumor. Large, welldesigned screening studies, even in the mutated BRCA1/2 families, have thus far failed to decrease ovarian cancer mortality in prospective testing. Circulating DNA approaches have also been unsuccessful so far. Screening for ovarian cancer is currently not recommended outside TABLE 94-1  Staging and Survival in Gynecologic Malignancies STAGE OVARIAN 5-YEAR SURVIVAL, % ENDOMETRIAL 5-YEAR SURVIVAL, % CERVIX 5-YEAR SURVIVAL, % — — Carcinoma in situ I Confined to ovary 88–95 Confined to corpus >90 Confined to uterus II Confined to pelvic organs 70–80 Involves corpus and cervix III Intra-abdominal spread to omentum, diaphragm, or lymph nodes 20–40 Extends outside the uterus but not outside the true pelvis IV Spread outside abdominal cavity, parenchymal spread, and pleural effusion cytology 10–20 Extends outside the true pelvis or involves the bladder or rectum of a clinical trial, but a careful history for familial cancers and directed genetic testing for susceptibility genes are definitely appropriate. TREATMENT Ovarian Cancer Epithelial ovarian cancer can be divided into distinct “disease states” for the purpose of treatment selection, as shown in Fig. 94-1. Detection by ultrasonography generally can identify a complex ovarian mass as “suspicious,” but surgery by a skilled gynecologic oncologist remains the preferred initial diagnostic and therapeutic option for an isolated adnexal mass or a more involved picture of peritoneal involvement. The amount of residual visible cancer at the end of a primary operation is strongly predictive of outcome and is paired with histology, grade, and stage to determine prognosis and treatment. Metastatic disease to the ovary can be seen from primary tumors of the colon, appendix, stomach (Krukenberg tumors), and breast. Needle biopsy of adnexal masses is contraindicated to avoid malignant contamination of the peritoneal cavity with malignant cells. Typically, women undergo laparoscopic evaluation Primary Treatment First Remission Maintenance Consolidation Diagnostic surgery Primary debulking Interval debulking HRD abnormal -> Poly-(ADP-ribose)- polymerase inhibitor for 2 y Platinum complex + taxane Chemotherapy HRD wild type No treatment Platinum-Resistant/Recurrent Disease Persistent cancer following platinum treatment or recurrence within 6 months of last platinum dose Single-agent treatment with or without bevacizumab: Liposomal doxorubicin, topotecan, docetaxel, weekly paclitaxel, gemcitabine, vinorelbine, pemetrexed, etoposide, bevacizumab, mirvetuximab, soravtansine Investigational therapy Death From Disease FIGURE 94-1  Disease states model of epithelial ovarian cancer and its treatment. Each box represents a relatively homogenous group of patients who share a palette of potential treatment choices and have a similar prognosis. The arrows indicate that a single patient may move from one state to another during the course of her illness, and the choice of treatments will become different in her new disease state. HRD, homologous recombination deficiency. ~75 Invades beyond uterus but not to pelvic wall 45–60 Extends to pelvic wall and/ or lower third of vagina, or hydronephrosis ~20 Invades mucosa of bladder or rectum or extends beyond the true pelvis and unilateral salpingo-oophorectomy for diagnostic purposes. If pathology reveals a primary ovarian malignancy or the laparoscopy proves disseminated disease is present, then the procedure should be followed by a total hysterectomy, removal of the remaining tube and ovary, omentectomy, and pelvic node sampling along with biopsies of the peritoneal cavity and diaphragms. This extensive surgical procedure is performed because ~30% of tumors that, by visual inspection, appear to be confined to the ovary have already disseminated to the peritoneal cavity and/or surrounding lymph nodes. As with axillary dissections in breast cancer, node sampling is diagnostic, but full lymphadenectomy appears to provide little or no additional therapeutic advantage over nodal sampling. The tar­ get outcome of an ovarian cancer surgery is always an R0 resection (no visible residual cancer). The less favorable “optimal resection” (no residual disease >1 cm in size) is still clinically useful, and the prognosis of those patients is much better than that of patients who are left with >1 cm of disease at the end of surgery. These “suboptimally debulked” patients derive very little benefit from their surgery. If large deposits of unresectable residual tumor are anticipated, the surgery should be delayed until after several cycles of neoadjuvant chemotherapy. Such “interval debulking” surgery CHAPTER 94 Gynecologic Malignancies Cure of Disease Platinum-Sensitive Relapse Subsequent Remission • Interval surgery • Maintenance therapy with poly-(ADP-ribose)- polymerase inhibitors • Carboplatin with either liposomal doxorubicin, paclitaxel, or gemcitabine • Bevacizumab achieves similar results to primary surgery with diminished surgical morbidity and more timely chemotherapy. Patients without gross residual disease (R0 resection) after resection have a median sur­ vival in excess of 60 months, compared to 28–42 months for those left with macroscopic tumor or those undergoing interval debulk­ ing, regardless of treatment strategy. After appropriate surgical treatment, primary chemotherapy will consist of combination treatment with paclitaxel and carbo­ platin. Primary chemotherapy can be delivered intravenously, or alternatively, some therapy can be directly administered into the peritoneal cavity via an indwelling catheter. The intraperitoneal approach is technically more difficult and is increasingly replaced by carboplatin and paclitaxel, which appears to offer similar results. Although interest in immunotherapy or chemoimmunotherapy has been high, immunotherapeutics have not yet improved primary chemotherapy. With optimal debulking surgery and platinum-based chemo­ therapy, 70% of women who present with advanced-stage tumors show tumor reduction, and 40–50% experience a complete remis­ sion with normalization of their CA-125, computed tomography (CT) scans, and physical examination. For women with evidence of functional homologous DNA repair defects, administration of oral poly-ADP ribose polymerase inhibitors (PARPi) such as nirapa­ rib, olaparib, or rucaparib will improve survival outcomes when administered at the completion of intravenous chemotherapy as consolidation. These drugs substantially delay recurrence and pro­ vide survival advantages as well. In the majority of patients, disease still recurs within 1–4 years from the completion of their primary therapy. CA-125 levels often increase as a first sign of relapse, and CT scan findings are eventually confirmatory. Recurrent disease is often successfully managed for years but rarely cured, despite a growing panel of chemotherapeutic agents and antibody-drug con­ jugates. Additional surgical therapy does not appear to extend sur­ vival in randomized trials. Patients with a treatment-free interval are often best treated with additional platinum doublets, combining carboplatin with liposomal doxorubicin, gemcitabine, or a taxane. Eventually all women who experience relapse develop chemother­ apy-refractory disease. Refractory ascites, poor bowel motility, and obstruction or tumor-infiltrated aperistaltic bowel are all common premorbid events. Limited surgery to relieve intestinal obstruction, localized radiation therapy to relieve pressure or pain from masses, or palliative chemotherapy may be helpful. Agents with >15% response rates include gemcitabine, topotecan, liposomal doxorubi­ cin, and bevacizumab. Five-year survival correlates with the stage of disease: stage I, 90–95%; stage II, 70–80%; stage III, 25–40%; stage IV, 10–15% (Table 94-1). Prognosis is improved by lower histologic grade and presence of BRCA1 or BRCA2 germline mutation. PART 4 Oncology and Hematology ■ ■UNCOMMON OVARIAN TUMORS Low Malignant Potential Tumors (Borderline Tumors)  These type 1 tumors are found in younger women (age 30–50 years) and are indolent in behavior, and few of these patients will succumb to their tumors (10-year survival may approach 98%), although recur­ rence is not uncommon. Certain features, such as micropapillary histology and microinvasion, are linked to more aggressive behavior. Tumors of low malignant potential have different mutations includ­ ing mutations BRAF or KRAS and cyclin-dependent kinase inhibitor (CDKN) 2A/2B deletion. Borderline tumor patients are managed pri­ marily by surgery, but targeted therapy for the RAS/RAF pathway and hormonal treatments sometimes have benefit. Stromal Tumors  Approximately 7% of ovarian neoplasms are stromal tumors, with ~1800 cases expected each year in the United States. Ovarian stromal tumors or sex cord tumors are most common in women in their fifties or sixties, but tumors can present at any age. These tumors arise from the mesenchymal components of the ovary, including both steroid-producing cells and fibroblasts. Most of these tumors are indolent tumors with limited metastatic potential and pres­ ent as unilateral solid masses. These tumors primarily are discovered by the detection of an abdominal mass, sometimes with abdominal pain due to ovarian torsion, intratumoral hemorrhage, or rupture. Rarely, stromal tumors can produce estrogen and present with breast tender­ ness as well as precocious puberty in children, menstrual disturbances in reproductively active women, or postmenopausal bleeding. In some women, estrogen-associated secondary malignancies, such as endo­ metrial or breast cancer, may present as synchronous malignancies. Sertoli-Leydig tumors often present with hirsutism and virilization due to increased production of androgens. Hormonally inert tumors include fibromas, which present as solitary masses often in association with ascites and occasionally hydrothorax, also known as Meigs’s syn­ drome. A subset of these tumors presents in individuals with a variety of inherited disorders that predispose them to mesenchymal neoplasia including Ollier’s disease (juvenile granulosa cell tumors) and PeutzJeghers syndrome (ovarian sex cord tumors). The treatment of these tumors is primarily complete surgical resection, without adjuvant che­ motherapy. Chemotherapy with carboplatin and paclitaxel is generally reserved for either unresectable or multiply recurrent tumors. Germ Cell Tumors of the Ovary  Germ cell tumors, like their counterparts in the testis, are cancers of germ cells. These totipotent cells contain the programming for differentiation to essentially all tis­ sue types, and hence, the germ cell tumors include a histologic menag­ erie of bizarre tumors, including benign teratomas (dermoid cysts) and a variety of malignant tumors, such as dysgerminoma, immature teratomas, yolk sac malignancies, and choriocarcinomas. Benign tera­ toma (or dermoid cyst) is the most common germ cell neoplasm of the ovary and often presents in young women. These tumors include a complex mixture of differentiated tissue including tissues from all three germ layers. In older women, these differentiated tumors can develop malignant transformation, most commonly squamous cell carcinomas. Malignant germ cell tumors include dysgerminomas, yolk sac tumors, immature teratomas, and embryonal and choriocarcinomas. Germ cell tumors can present at all ages, but the peak age of presentation tends to be in adolescents. Typically, these tumors will become large ovarian masses, which eventually present as palpable low abdominal or pelvic masses. Like sex cord tumors, torsion or hemorrhage may present urgently or emergently as acute abdominal pain. Some germ cell tumors produce elevated levels of human chorionic gonadotropin (hCG) or α-fetoprotein (AFP). Unlike epithelial ovarian cancer, these tumors have a higher proclivity for nodal or hematogenous metastases. Germ cell tumors typically present in women who are of childbearing age, and because bilateral tumors are uncommon (except in dysgermi­ noma, 10–15%), the typical treatment is unilateral oophorectomy or salpingo-oophorectomy with lymph node sampling. Most commonly, women with advanced malignant germ cell tumors typically receive bleomycin, etoposide, and cisplatin (BEP) chemotherapy, in an analo­ gous fashion to the treatment of testicular cancers. In the majority of these women, even those with advanced-stage disease, cure is expected. Dysgerminoma is the ovarian counterpart of testicular seminoma and is highly curable. Although the tumor is highly radiation-sensitive, radiation produces infertility in many patients. BEP chemotherapy is as effective or more so without causing infertility. FALLOPIAN TUBE CANCER Transport of the egg to the uterus occurs through the fallopian tube, with the distal ends of these tubes composed of fimbriae that drape about the ovarian surface and capture the egg as it erupts from the ovarian cortex. As described above, the majority of type 2 ovarian cancers are now thought to arise from the tubal epithelium. Fallopian tube malignancies are typically of serous histology and share the same biology and recommended treatment approaches as serous ovar­ ian cancer. These tumors often present as clinically isolated adnexal masses, but like ovarian cancer, these tumors spread relatively early throughout the peritoneal cavity. Fallopian tubal cancers have a natural history and treatment that are essentially identical to ovarian cancer (Table 94-1). CERVICAL CANCER ■ ■ETIOLOGY AND GENETICS Cervical cancer is the second most common and the most lethal malignancy in women worldwide. Infection with high-risk strains of human papillomavirus (HPV) is the primary neoplastic-initiating event in the vast majority of women with invasive cervical cancer. This double-stranded DNA virus infects epithelium near the transformation zone of the cervix where underlying columnar epithelium becomes squamous epithelium. More than 60 types of HPV are known, with ~20 types having the ability to generate high-grade dysplasia and malignancy. HPV16 and 18 are the types most frequently associated with high-grade dysplasia, but types 31, 33, 35, 52, and 58 are also considered to be high-risk variants. The large majority of sexually active adults are exposed to HPV, and most women clear the infection without specific intervention. The 8-kb HPV genome encodes seven early genes, most notably E6 and E7, which can bind to RB and p53, respectively. High-risk types of HPV encode E6 and E7 molecules that are particularly effective at inhibiting the normal cell cycle checkpoint functions of these regulatory proteins, leading to immortalization but not full transformation of cervical epithelium. A minority of women will fail to clear the infection, with subsequent HPV integration into the host genome. Over as little as a few months to several years, some of these persistently infected women develop worsening dysplasia, a premalignant condition that, untreated, can progress to cervical carci­ noma. Complete transformation to cancer occurs over a period of years and almost certainly requires the acquisition of other genetic mutations within the infected and immortalized epithelium. In 2024, more than half a million new cases of cervical cancer will occur worldwide, with an estimated >300,000 deaths. Cancer incidence is particularly high in women residing in Central and South America, the Caribbean, and southern and eastern Africa. The mortality rate is disproportionately high in Africa. In the United States, an estimated 13,960 women will be diagnosed with cervical cancer in 2024 and ~4300 women will die of the disease. In the integrated genomic characterization of cervical cancer by The Cancer Genome Atlas (TCGA), integration of HPV sequences was found in all of the HPV18-linked cancers and over three-quarters of the HPV16 cancers. The cervical tumors also showed a charac­ teristic APOBEC (apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like; a family of cytidine deaminases that edit DNA and are endogenous mutagenic enzymes) pattern of mutagenesis, with ERBB3, CASP8, and TGFRB2 identified as significantly mutated genes presumably linked to progression from dysplasia to carcinoma. In the much smaller number of HPV-negative cancers, which are more com­ mon in older women, mutations in oncogenes KRAS, ARID1A, and PTEN were frequently seen. The clinical behavior of these cancers is likely to be different. ■ ■HPV INFECTION AND PREVENTION The Pap smear is the primary detection method for asymptomatic preinvasive cervical dysplasia of squamous epithelial lining during a gynecologic exam. Because the progression from dysplasia to cervi­ cal cancer takes several years, annual (or longer interval) screening and prevention strategies that detect precancerous dysplasia and carcinoma in situ can be implemented successfully. Annual or bian­ nual cervical scraping for cytology (Pap smear) is highly effective in reducing the incidence of cervical cancer by early detection and subsequent surgical treatment of premalignant disease. The incorpo­ ration of HPV testing by polymerase chain reaction (PCR) or other molecular techniques increases the sensitivity of detecting cervical pathology but at the cost of lower sensitivity in that it identifies many women with transient infections who require no specific medical intervention. Unfortunately, both the collection of a Pap smear and its cytologic evaluation require infrastructure beyond the means of many middle- and low-income countries. High-throughput, low-technology prevention strategies and point-of-care testing are needed to identify and treat women bearing high-risk cervical dysplasia to prevent cancer development. A primary prevention strategy relies on HPV vaccines. In the United States, the Gardasil-9 vaccine protects against HPV types 6, 11, 16, 18, 31, 33, 45, 52, and 58. Vaccination of girls and women between ages 9 and 45 years is recommended with three injections (0, 2, and 6 months). Vaccination before the initiation of sexual activity dra­ matically reduces the rate of high-risk HPV infection and subsequent dysplasia. Vaccination of both boys and girls is increasingly considered to reduce the risk of HPV-induced cancers of the pharynx. Vaccinated women are still at risk for HPV infection and still benefit from standard Pap smear screening. ■ ■CLINICAL PRESENTATIONS Risk Factors  Clinical risk factors include the prevalence of highrisk HPV subtypes in the population and HPV infection–linked features such as a high number of sexual partners, early age of first intercourse, and history of venereal disease. Smoking is a cofactor; heavy smokers have a higher risk of dysplasia with HPV infection. HIV infection, especially when associated with low CD4+ T-cell counts, is associated with a higher rate of high-grade dysplasia and likely a shorter latency period between infection and invasive disease. Histo­ logically, the majority (80%) of cervical malignancies are squamous cell carcinomas associated with HPV, but adenocarcinomas are also HPV related, and both arise in the transitional zone of the endocervi­ cal canal; the lesions in the canal or cervical glands may not be seen by visual inspection of the cervix and can be missed by Pap smear screening. Other malignancies, such as vulvar cancer, anal cancer, and, increasingly, pharyngeal cancer, are also linked to HPV infection. CHAPTER 94 Gynecologic Malignancies Diagnosis of Cervical Cancer  Early cancer of the cervix is asymptomatic, and this biology underlies the recommendations for routine gynecologic care. Larger, invasive carcinomas often have symptoms or signs including postcoital spotting or intermenstrual cycle bleeding or menometrorrhagia. Foul-smelling or persistent yellow discharge may also be present. Symptoms such as pelvic or sacral pain suggest lateral extension into the pelvic nerve plexus by either the primary tumor or a pelvic node metastasis and indicate advanced-stage disease. Likewise, flank pain from hydronephrosis from ureteral compression or deep-venous thrombosis from iliac vessel compression suggests either extensive nodal disease or direct extension of the primary tumor to the pelvic sidewall. The most common finding upon physical exam is a visible tumor on the cervix, but deeper tumors in the cervical os and glands should be considered. Larger tumors may be identified by inspection and biopsied directly. Staging of cervical cancer is performed by expert clinical exam. Stage I cervical tumors are confined to the cervix, whereas stage II tumors extend into the upper vagina or paracervical soft tissue (Fig. 94-2). Stage III tumors extend to the lower vagina or the pelvic sidewalls, whereas stage IV tumors invade the bladder or rectum or have spread to distant sites. While radiographic studies are not part of the formal clinical staging of cervical cancer, treatment planning requires them for appropriate therapy. CT can detect hydronephrosis indicative of pelvic sidewall disease but is not accurate at evaluating other pelvic structures. Mag­ netic resonance imaging (MRI) is more accurate at estimating uterine extension and paracervical extension of disease into soft tissues typi­ cally bordered by broad and cardinal ligaments that support the uterus in the central pelvis. Very small stage I cervical tumors can be treated with a variety of surgical procedures, but minimally invasive surgery has inferior outcome compared to standard open hysterectomy. In young women desiring to maintain fertility, radical trachelectomy removes the cervix with subsequent anastomosis of the upper vagina to the uterine corpus; however, subsequent pregnancies may be more problematic. Patients with large stage I cervical tumors (4 cm) confined to the cervix and all stage II to IV patients are treated with radiation therapy in combination with cisplatin-based immunochemotherapy with concurrent PD-1 blockers. This multimodality treatment can offer the patient with advanced-stage disease a 40–80% chance of cure depending on the clinical circumstances. Immunotherapy with PD-1 blockade, cisplatin, paclitaxel, bevacizumab, and tisotumab vedotin are generally considered as appropriate palliative choices for metastatic Staging of cervix cancer Stage I II III IV Disease to pelvic wall or lower 1/3 vagina Disease beyond cervix but not to pelvic wall or lower 1/3 of vagina Confined to cervix Extent of tumor Carcinoma in situ 65% 85% 5-year survival 100% 4% Stage at presentation 28% 47% Uterine cavity Fundus Fallopian tube Uterine wall Corpus IIB Internal os IIIB Cervix IIA IIIA External os Vagina FIGURE 94-2  Anatomic display of the stages of cervix cancer defined by location, extent of tumor, frequency of presentation, and 5-year survival. PART 4 Oncology and Hematology cervical cancer patients. Secondary chemotherapy confers minimal improvement in most patients. Additional immunotherapies targeting HPV antigens are potential avenues for improved outcomes in recur­ rent, unresectable cancers of the cervix. UTERINE CANCER ■ ■EPIDEMIOLOGY Several different tumor types arise in the uterine corpus. Most tumors arise in the glandular lining and are endometrial adenocarcinomas. Benign (leiomyomas) and malignant smooth muscle tumors (leiomyo­ sarcomas) can also arise in the uterus and have very different clinical features. The endometrioid histologic subtype is the most common gynecologic malignancy in the United States. In 2024, the American Cancer Society predicted that 66,200 new cancers of the uterine corpus are expected in 2024 with 13,030 resulting deaths. Development of these tumors is a multistep process, with estrogen playing an impor­ tant early role in driving endometrial gland proliferation. Relative overexposure to this class of hormones is the principal risk factor for the subsequent development of endometrioid tumors. In contrast, pro­ gestins drive glandular maturation and are protective. Hence, women with high endogenous or pharmacologic exposure to estrogens, espe­ cially if unopposed by progesterone, are at higher risk for endometrial cancer. Obese women, women treated with postmenopausal estrogens, or women with estrogen-producing tumors are at higher risk for endo­ metrial cancer. In addition, long-term treatment with tamoxifen, which has antiestrogenic effects in breast tissue but can show weak estrogenic effects in uterine epithelium, is associated with an increased risk of endometrial cancer. Genetics  Women with a germline mutation in one of a series of DNA mismatch repair genes associated with the Lynch syndrome, also known as hereditary nonpolyposis colon cancer (HNPCC) syndrome, are at increased risk for endometrioid endometrial carcinoma. These individuals have germline mutations in MSH2, MLH1, and, in rare cases, PMS1 and PMS2. Individuals who carry these mutations typi­ cally have a family history of cancer and are at markedly increased risk for colon cancer and modestly increased risk for ovarian cancer and a variety of other tumors. Middle-aged women with HNPCC carry a 4% annual risk of endometrial cancer and a relative overall risk of ~200fold as compared to age-matched women without HNPCC. In sporadic cancers, secondary events such as mutation of the PI3K gene or the loss of the PTEN tumor-suppressor gene likely serve as secondary genetic “hits” in the carcinogenesis related to estrogenic excess. The molecular events that underlie less common endo­ metrial cancers such as clear cell and papillary serous tumors of the uterine corpus are not well understood. Invades bladder, rectum or metastasis ■ ■PATHOLOGY Approximately 75–80% of endometrial cancers are adenocarcinomas and have been characterized as type 1 (estrogenlinked) endometrial cancers and type 2 cancers that have less clear associations with estrogens (clear cell cancers, serous cancers, and mucinous cancers). Endo­ metrial serous cancers show TP53 loss of function and behave clinically more like ovarian cancers with high risk for sys­ temic recurrence. Prognosis for endome­ trial cancer depends on stage, histologic grade, and depth of myometrial invasion. 7% 35% 21% Pelvic side wall ■ ■CLINICAL PRESENTATION The majority of women with tumors of the uterine corpus present with post­ menopausal vaginal bleeding due to shedding of the malignant endometrial lining. Premenopausal women often will present with atypical bleeding between typical menstrual cycles. These signs typically bring a woman to the attention of health care providers, and the majority of women have early-stage disease in which the tumor is confined to the uterine corpus and, consequently, have a high cure rate. Diagnosis is typically established by endometrial biopsy. Type 1 tumors may spread to pelvic or para-aortic lymph nodes and are gen­ erally subjected to sentinel lymph node biopsy at the time of primary surgery. Serous tumors tend to have patterns of spread similar to highgrade serous ovarian cancer, and patients may present with omental/ peritoneal disease and sometimes ascites. Some women presenting with uterine sarcomas will present with pelvic pain. Uterine sarcomas (carcinosarcomas and leiomyosarcomas) commonly are found by detection of symptomatic large pelvic masses that may not be associ­ ated with dysfunctional vaginal bleeding. TREATMENT Uterine Cancer Most women with endometrial cancer have disease that is local­ ized to the uterus (75% are stage I, Table 94-1), and definitive treatment typically involves a hysterectomy with removal of the ovaries and fallopian tubes. The resection of lymph nodes does not improve outcome, but sentinel node resection provides important staging and prognostic information. Node involvement defines stage IIIC disease, which is treated with immunochemotherapy. Tumor grade and depth of invasion are two key prognostic vari­ ables in early-stage tumors, and women with low-grade and/or minimally invasive tumors (<50% myometrial penetration) are typically observed after definitive surgical therapy. Patients with high-grade tumors or tumors that are deeply invasive (stage IB) are at higher risk for pelvic recurrence or recurrence at the vaginal cuff, which is typically prevented by intravaginal brachytherapy. It is now routine to test all endometrial cancers for microsatellite instability (MSI) with a larger number of mutations in the tumor. MSI cancers, when recurrent or present at an advanced stage, are likely to respond to immune checkpoint therapy and PD-1–targeted therapy should be part of treatment for those patients. Women with regional metastases or metastatic disease (3% of patients) with low-grade tumors can be treated with progesterone or tamoxifen. In contrast, poorly differentiated tumors lack hormone receptors and are typically unresponsive to hormonal manipulation. The role of adjuvant chemotherapy in stage I–II disease is generally restricted to serous endometrial cancers. For more advanced-stage cancers (stage III–IV), chemotherapy and/or immune checkpoint blockade are administered because of the higher rates of recurrent systemic disease. Carboplatin and paclitaxel combinations with immune targeting agents are the current standard of care. Chemo­ therapy for metastatic disease is delivered with palliative intent. Even patients with advanced cancer and known mismatch repair deficits may respond well to immunotherapy with antagonists of the PD-1/PD-L1 axis. Lenvatinib and pembrolizumab (even for microsatellite-stable tumors) have become the most common second-line treatments. Other potentially active treatments include bevacizumab and mammalian target of rapamycin (mTOR) inhibi­ tors (e.g., temsirolimus). Newer antibody-drug conjugates may have good responses in patients with expression of the target antigens. Carcinosarcomas of the uterus (also called Müllerian tumors) con­ tain both mesenchymal and epithelial components but will often respond to paclitaxel and platinum complex therapy. Other uterine sarcomas require an entirely different approach and need histologyspecific consideration. The most common are the leiomyosarcomas of the uterus, which are treated with docetaxel/gemcitabine at recurrence but do not appear to benefit from adjuvant therapy. Ifosfamide/doxorubicin and trabectedin can have some benefit in refractory disease. GESTATIONAL TROPHOBLASTIC TUMORS Gestational trophoblastic diseases represent a spectrum of neoplasia from benign hydatidiform mole to choriocarcinoma due to persistent trophoblastic disease associated most commonly with molar preg­ nancy but occasionally seen after normal gestation. The most common presentations of trophoblastic tumors are partial and complete molar pregnancies. These represent approximately 1 in 1500 conceptions in developed Western countries. The incidence widely varies globally, with areas in Southeast Asia having a much higher incidence of molar pregnancy. Regions with high molar pregnancy rates are often associ­ ated with diets low in carotene and animal fats. ■ ■RISK FACTORS Trophoblastic tumors result from the outgrowth or persistence of placental tissue. They arise most commonly in the uterus but can also arise in other sites such as the fallopian tubes due to ectopic pregnancy. Risk factors include poorly defined dietary and environmental factors as well as conceptions at the extremes of reproductive age, with the incidence particularly high in females conceiving at younger than age 16 or older than age 50. In older women, the incidence of molar preg­ nancy might be as high as one in three, likely due to increased risk of abnormal fertilization of the aged ova. Most trophoblastic neoplasms are associated with complete moles, diploid tumors with all genetic material from the paternal donor (known as uniparental disomy). This is thought to occur when a single sperm fertilizes an enucleate egg that subsequently duplicates the paternal DNA. Trophoblastic proliferation occurs with exuberant villous stroma. If pseudopregnancy extends out past the 12th week, fluid progressively accumulates within the stroma, leading to “hydropic changes.” Fetal development does not occur in complete moles. Partial moles arise from the fertilization of an egg with two sperm cells; hence, two-thirds of genetic material is paternal in these triploid tumors. Hydropic changes are less dramatic, and fetal development can often occur through late first trimester or early second trimester, at which point spontaneous abortion is common. Laboratory findings will include excessively high hCG and high AFP. The risk of persistent gestational trophoblastic disease after partial mole is ~5%. Complete and partial moles can be noninvasive or invasive. Myometrial invasion occurs in no more than one in six complete moles and a lower portion of partial moles. ■ ■PRESENTATION OF INVASIVE TROPHOBLASTIC DISEASE The clinical presentation of molar pregnancy is changing in developed countries due to the early detection of pregnancy with home pregnancy kits and the very early use of Doppler and ultrasound to evaluate the early fetus and uterine cavity for evidence of a viable fetus. Thus, in these countries, the majority of women presenting with trophoblastic disease have their moles detected early and have typical symptoms of early pregnancy including nausea, amenorrhea, and breast tenderness. With uterine evacuation of early complete and partial moles, most women experience spontaneous remission of their disease as moni­ tored by serial serum β-hCG levels. These women require no chemo­ therapy. Patients with persistent elevation of β-hCG or rising β-hCG after uterine evacuation have persistent or actively growing gestational trophoblastic disease and require therapy. Most series suggest that between 15 and 25% of women will have evidence of persistent gesta­ tional trophoblastic disease after molar evacuation. In women who lack access to prenatal care, presenting symptoms can be life-threatening, including the development of preeclampsia or even eclampsia. Hyperthyroidism can also be seen with very high β-hCG values. Evacuation of large moles can be associated with lifethreatening complications including uterine perforation, volume loss, high-output cardiac failure, and adult respiratory distress syndrome (ARDS). For women with evidence of rising β-hCG or radiologic confir­ mation of metastatic or persistent regional disease, prognosis can be estimated through a variety of scoring algorithms that identify women at low, intermediate, and high risk for requiring multiagent chemother­ apy. In general, women with widely metastatic nonpulmonary disease, very elevated β-hCG, and prior normal antecedent term pregnancy are considered at high risk and typically require multiagent chemotherapy at an expert center for cure. Even very advanced gestational tropho­ blastic disease is almost uniformly curable when managed by an expert in this rare malignancy. CHAPTER 94 Gynecologic Malignancies TREATMENT Invasive Trophoblastic Disease Management of invasive trophoblastic disease should be 100% curative, and complex patients should only be managed by clini­ cians experienced in this disease. The management for a persistent and rising β-hCG after evacuation of a molar conception is typi­ cally chemotherapy, although surgery can play an important role for chemotherapy-resistant disease that is isolated in the uterus (especially if childbearing is complete) or to control hemorrhage. For women wishing to maintain fertility or with metastatic disease, the preferred treatment is chemotherapy or immunotherapy tar­ geting the PD-1 axis. Trophoblastic disease is exquisitely sensitive to chemotherapy, and guided by serial serum β-hCG testing, suc­ cessful, curative treatment is the rule. Single-agent treatment with dactinomycin or methotrexate cures 90% of women with low-risk disease. Patients with high-risk disease (very high β-hCG levels, presentation ≥4 months after pregnancy, brain or liver metastases, failure of methotrexate therapy) are typically treated with mul­ tiagent chemotherapy (etoposide, methotrexate, and dactinomycin, alternating with cyclophosphamide and vincristine [EMA-CO]), which is typically curative even in women with extensive metastatic disease. A regimen of cisplatin and etoposide alternating with etoposide/methotrexate/dactinomycin is used for the highest-risk patients. In the highest-risk patients with liver, lung, and brain metastases, hemorrhage from the rich tumor vasculature is a major risk during chemotherapy initiation. Cured women may become pregnant again without evidence of increased fetal or maternal complications. ■ ■FURTHER READING Longo DL: Personalized medicine for primary treatment of serous ovarian cancer. N Engl J Med 381:2471, 2019. Lu KH, Broaddus RR: Endometrial cancer. N Engl J Med 383:2053, 2020. Moore KN et al: Mirvetuximab soravtansine in FRα-positive, platinum-resistant ovarian cancer. N Engl J Med 389:2162, 2023. # 24 - 95 Primary and Metastatic Tumors of the Nervous System ### 95 Primary and Metastatic Tumors of the Nervous System Mary Jane Lim-Fat, Patrick Y. Wen Primary and Metastatic Tumors of the Nervous System An estimated 95,000 people will be diagnosed with a primary brain tumor annually in the United States. At least 27,000 of these tumors are malignant, and most of these are gliomas. Meningiomas account for 41% of all central nervous system (CNS) tumors, vestibular schwanno­ mas 10%, and CNS lymphomas ~2%. Brain metastases are three times more common than all primary brain tumors combined and are diag­ nosed in ~150,000 people each year. Metastases to the leptomeninges and epidural space of the spinal cord each occur in ~2–12% of patients with systemic cancer and are also a major cause of neurologic disability. APPROACH TO THE PATIENT Primary and Metastatic Tumors of the Nervous System PART 4 Oncology and Hematology CLINICAL FEATURES Brain tumors of any type can present with a variety of symptoms and signs that fall into two categories: general and focal; patients often have a combination of the two (Table 95-1). General symp­ toms include headache, with or without nausea or vomiting, cog­ nitive difficulties, personality change, and gait disorder. These symptoms arise when the enlarging tumor and its surrounding edema cause an increase in intracranial pressure or compression of cerebrospinal fluid (CSF) circulation, leading to hydrocephalus. The classic brain tumor headache predominates in the morning and improves during the day, but this pattern is seen in a minority of patients. Headaches are often holocephalic but can be ipsilateral to the side of a tumor. Occasionally, headaches have features of a typi­ cal migraine with unilateral throbbing pain associated with visual scotoma. Personality changes may include apathy and withdrawal from social situations, mimicking depression. Focal or lateralizing findings include hemiparesis, aphasia, or visual field defect. Later­ alizing symptoms are typically subacute and progressive; language difficulties may be mistaken for confusion. Seizures are common, occurring in ~25% of patients with brain metastases or malignant gliomas, and are the presenting symptom in up to 90% of patients with a low-grade glioma. All seizures arising from a brain tumor will have a focal onset whether or not it is apparent clinically. NEUROIMAGING Cranial magnetic resonance imaging (MRI) is the preferred diag­ nostic test for any patient suspected of having a brain tumor and should be performed with gadolinium contrast administration. TABLE 95-1  Symptoms and Signs at Presentation of Brain Tumors HIGH-GRADE GLIOMA (%) LOW-GRADE GLIOMA (%) MENINGIOMA (%) METASTASES (%) Generalized Impaired cognitive function Hemiparesis Headache Lateralizing Seizures 70+ Aphasia <5 — Visual field deficit — — — Computed tomography (CT) scan should be reserved for those patients unable to undergo MRI. Malignant brain tumors—whether primary or metastatic—typically enhance with gadolinium, have central areas of necrosis, and are surrounded by edema of the neigh­ boring white matter. Low-grade gliomas usually do not enhance with gadolinium and are best appreciated on fluid-attenuated inver­ sion recovery (FLAIR) MRI sequences. Meningiomas have a typical appearance on MRI because they are dural-based enhancing tumors with a dural tail and compress but do not invade the brain. Dural metastases or a dural lymphoma can have a similar appearance. Imaging is characteristic for many primary and metastatic tumors and sometimes will suffice to establish a diagnosis when the location precludes surgical intervention (e.g., brainstem glioma). Functional MRI is useful in presurgical planning to define eloquent sensory, motor, or language cortex. Positron emission tomography (PET) is useful in determining the metabolic activity of the lesions seen on MRI; MR perfusion and spectroscopy can provide infor­ mation on blood flow or tissue composition. These techniques may help distinguish tumor progression from tissue necrosis due to treatment with radiation and chemotherapy. Neuroimaging is the only test necessary to diagnose a brain tumor. Laboratory tests are rarely useful, although patients with metastatic disease may have elevation of a serum tumor marker (e.g., β human chorionic gonadotropin [β-hCG] from testicular cancer). Additional testing such as cerebral angiogram, electroencephalogram (EEG), or lum­ bar puncture is rarely indicated or helpful. TREATMENT Brain Tumors Therapy of any intracranial malignancy requires both symptomatic and definitive treatments. Definitive treatment is based on the specific tumor type and includes surgery, radiotherapy, and chemo­ therapy. However, symptomatic treatments apply to brain tumors of any type. Most high-grade malignancies are accompanied by sub­ stantial surrounding edema, which contributes to neurologic dis­ ability and raised intracranial pressure. Glucocorticoids are highly effective at reducing perilesional edema and improving neurologic function, often within hours of administration. Dexamethasone has been the glucocorticoid of choice because of its relatively low mineralocorticoid activity; initial doses are 4–12 mg/d in one to two daily doses. Glucocorticoids rapidly ameliorate symptoms and signs, but their long-term use causes substantial toxicity including insomnia, weight gain, diabetes mellitus, steroid myopathy, and personality changes. Consequently, a taper is indicated as definitive treatment is administered and the patient improves. Patients with brain tumors who present with seizures require antiepileptic drug therapy. Prophylactic antiepileptic drugs are occasionally used in the perioperative setting, but there is no role for extended use in patients who have not had a seizure. The agents of choice are drugs that do not induce the hepatic micro­ somal enzyme system. These include levetiracetam, topiramate, lamotrigine, valproic acid, and lacosamide (Chap. 447). Other drugs, such as phenytoin and carbamazepine, are used less fre­ quently because they are potent enzyme inducers that can interfere with both glucocorticoid and chemotherapy metabolism. Venous thromboembolic disease occurs in 20–30% of patients with HGGs or brain metastases. Prophylactic anticoagulants should be used during hospitalization and in nonambulatory patients. Those who have had either a deep vein thrombosis or a pulmonary embolus can receive therapeutic doses of anticoagulation safely and without increasing the risk of hemorrhage into the tumor. Inferior vena cava filters are reserved for patients with absolute contraindications to anticoagulation such as recent craniotomy. PRIMARY BRAIN TUMORS ■ ■EPIDEMIOLOGY No etiology has been identified for most primary brain tumors. The only established risk factors are exposure to ionizing radiation (menin­ giomas, gliomas, and schwannomas) and immunosuppression (pri­ mary CNS lymphoma). There is no proven evidence for any association with exposure to electromagnetic fields including cellular telephones, head injury, foods containing N-nitroso compounds, or occupational risk factors. A small minority of patients have a family history of brain tumors. Some of these familial cases are associated with genetic syndromes (Table 95-2). ■ ■MOLECULAR PATHOGENESIS As with other neoplasms, brain tumors arise as a result of a multistep process driven by the sequential acquisition of genetic alterations. These include loss of tumor-suppressor genes (e.g., p53, cyclindependent kinase inhibitor 2A and 2B [CDKN2A/B], and phosphatase TABLE 95-2  Genetic Syndromes Associated with Primary Brain Tumors SYNDROME INHERITANCE GENE/PROTEIN ASSOCIATED TUMORS Cowden’s syndrome AD Mutations of PTEN (ch10p23) Dysplastic cerebellar gangliocytoma (Lhermitte-Duclos disease), meningioma, astrocytoma Familial schwannomatosis Sporadic Hereditary Mutations in INI1/SNF5 (ch22q11) Schwannomas, gliomas Gardner’s syndrome AD Mutations in APC (ch5q21) Medulloblastoma, glioblastoma, craniopharyngioma Gorlin syndrome (basal cell nevus syndrome) AD Mutations in Patched 1 gene (ch9q22.3) Medulloblastomas Basal cell carcinoma Li-Fraumeni syndrome AD Mutations in p53 (ch17p13.1) Gliomas, medulloblastomas Sarcomas, breast cancer, leukemias, others Lynch syndrome AD Mutations in MSH2, MSH1, MSH6, PMS2 Glioblastoma and other gliomas Gastrointestinal, endometrial, and other cancers Multiple endocrine neoplasia 1 (Wermer’s syndrome) AD Mutations in Menin (ch11q13) Pituitary adenoma, malignant schwannomas Parathyroid and pancreatic islet cell tumors NF1 AD Mutations in NF1/neurofibromin (ch17q12-22) NF2 AD Mutations in NF2/merlin (ch22q12) Bilateral vestibular schwannomas, astrocytomas, multiple meningiomas, ependymomas TSC (Bourneville disease) AD Mutations in TSC1/TSC2 (ch9q34/16) Subependymal giant cell astrocytoma, ependymomas, glioma, ganglioneuroma, hamartoma Turcot syndrome AD Mutations in APCa (ch5) Gliomas, medulloblastomas AR hMLH1 (ch3p21) Adenomatous colon polyps, adenocarcinoma VHL AD Mutations in VHL gene (ch3p25) Hemangioblastomas aVarious DNA mismatch repair gene mutations may cause a similar clinical phenotype, also referred to as Turcot syndrome, in which there is a predisposition to nonpolyposis colon cancer and brain tumors. Abbreviations: AD, autosomal dominant; APC, adenomatous polyposis coli; AR, autosomal recessive; ch, chromosome; NF, neurofibromatosis; PTEN, phosphatase and tensin homologue; TSC, tuberous sclerosis complex; VHL, von Hippel-Lindau. and tensin homolog on chromosome 10 [PTEN]) and amplification and overexpression of protooncogenes such as the epidermal growth factor receptor (EGFR) and platelet-derived growth factor receptors (PDGFR). The accumulation of these genetic abnormalities results in uncontrolled cell growth and tumor formation. Many brain tumors, including glioblastomas, are characterized by significant molecular heterogeneity, which contributes to the difficulty in developing effec­ tive therapies. Important progress has been made in understanding the molecular pathogenesis of several types of brain tumors, including glioblastoma and medulloblastoma, allowing them to be separated into different subtypes with different prognoses. This has led the World Health Organization (WHO) to issue an update on the classification of CNS tumors in 2016 that for the first time incorporated molecular param­ eters in addition to traditional histology into the diagnosis of brain tumors. The most recent 2021 WHO Classification of Tumors of the CNS further stressed the use of integrated diagnoses based on both molecular diagnostics and histology. This has improved the classifica­ tion of brain tumors, allowing for better understanding of the progno­ sis and optimal therapy for patients. INTRINSIC “MALIGNANT” TUMORS CHAPTER 95 ■ ■DIFFUSE GLIOMA Gliomas are the most common type of malignant primary brain tumor. The 2021 WHO Classification now differentiates gliomas as “adult type” or “pediatric type” based on molecular genetic differences. Both adult-type and pediatric-type diffuse gliomas can be subclassified into high- or low-grade glioma based on histology and are further charac­ terized by key molecular alterations (Table 95-3). Although uncom­ mon, pediatric-type diffuse gliomas also occur in adults, hence their inclusion here. Primary and Metastatic Tumors of the Nervous System Breast, endometrial, thyroid cancer, trichilemmomas Familial polyposis, multiple osteomas, skin and soft tissue tumors Schwannomas, astrocytomas, optic nerve gliomas, meningiomas Neurofibromas, neurofibrosarcomas, others Retinal angiomas, renal cell carcinoma, pheochromocytoma, pancreatic tumors and cysts, endolymphatic sac tumors of the middle ear TABLE 95-3  Summary of Gliomas and Relevant Molecular Alterations CHARACTERISTIC MOLECULAR ALTERATIONS TUMOR TYPE Adult-Type Diffuse Gliomas Astrocytoma, IDH-mutant IDH1, IDH2 Oligodendroglioma, IDH-mutant, 1p/19q-codeleted IDH1, IDH2, 1p/19q Glioblastoma, IDH wild type Chromosome 7 gain and 10 loss, TERT, EGFR Pediatric-Type Diffuse High-Grade Gliomas Diffuse midline glioma, H3 K27-altered H3 K27M, H3K27me3, EGFR, EZHIP Diffuse hemispheric glioma, H3 G34-mutant H3.3 G34R/V Diffuse pediatric-type high-grade glioma, H3 wild type and IDH wild type EGFR, PDGFRA, MYCN Pediatric-Type Diffuse Low-Grade Gliomas Diffuse low-grade glioma, MAPK pathway-altered MAPK pathway genes (BRAF V600E mutation, BRAF fusion, FGFR mutation) Abbreviations: IDH, isocitrate dehydrogenase; TERT, telomerase reverse transcriptase; EGFR, epidermal growth factor receptor; FGFR, fibroblast growth factor receptor; MAPK, mitogen-activated protein kinase; EZHIP, EZH inhibitor protein; PDGFRA, platelet-derived growth factor receptor alpha; MYCN, MYCN proto-oncogene. PART 4 Oncology and Hematology ■ ■ADULT-TYPE DIFFUSE GLIOMA Adult-type diffuse gliomas are classified based on the presence of a mutation in a key driver, the isocitrate dehydrogenase (IDH) gene, followed by the presence of 1p/19q co-deletion. Both of these molecu­ lar alterations have significant prognostic impact and lead to the emergence of three distinct groups: IDH-mutant astrocytoma (1p/19q intact), IDH-mutant oligodendroglioma (1p/19q co-deleted), and IDH wild-type glioblastoma. Diffuse gliomas can present rarely as widespread infiltration of the brain tissue without a focal mass. Such tumors usually present with cognitive problems, and the MRI demonstrates confluent, typically nonenhancing areas of increased signal on FLAIR sequences without significant mass effect. Formerly known as gliomatosis cerebri, these lesions are now categorized by the pathology identified on biopsy, but they can be diagnostically challenging when the nature of the imaging abnormalities is unclear. Often diagnosis is delayed until the patient develops worsening deficits or there is clear progression on imaging. Treatment is then determined by the pathology. Astrocytoma, IDH-Mutant  IDH-mutant astrocytoma can be further classified into grade 2, 3, or 4 based on histologic features, with higher grade tumors incorporating additional features of malignancy. CDKN2A/B homozygous deletion is associated with poor prognosis, and its presence confers a grade 4 to IDH-mutant astrocytomas with lower-grade histologic features. Low-grade (grade 2) IDH-mutant astrocytomas are infiltrative tumors that usually present with sei­ zures in young adults or can be detected incidentally. They appear as nonenhancing tumors with increased T2/FLAIR signal (Fig. 95-1). If feasible, patients should undergo maximal surgical resection, although complete resection is rarely possible because of the invasive nature of the tumor. In patients at higher risk for recurrence (subtotal resection or above the age of 40 years), there is evidence that radiation therapy (RT) followed by PCV (procarbazine, lomustine, and vincristine) or temozolomide chemotherapy may be of benefit. The tumor transforms to a higher-grade astrocytoma in most patients, leading to variable survival with a median of ~10 years. The IDH-inhibitor vorasidenib has been showed to be effective in delaying the progression-free sur­ vival and time to next intervention, and IDH inhibitors may become an integral part of the management for both IDH-mutant low-grade glioma astrocytoma and oligodendroglioma. High-grade IDH-mutant astrocytoma includes grade 3 astrocytoma (formerly termed anaplas­ tic astrocytoma) and grade 4 astrocytoma (previously IDH-mutant glioblastoma) and generally presents in the fourth and fifth decades FIGURE 95-1  Fluid-attenuated inversion recovery (FLAIR) MRI of a left frontal lowgrade astrocytoma. This lesion did not enhance. of life as variably enhancing tumors. Treatment is the same as for glio­ blastoma, consisting of maximal safe surgical resection followed by RT and adjuvant temozolomide alone or RT with concurrent and adjuvant temozolomide. The median survival for high-grade anaplastic astrocy­ toma can range from 3 to 9 years. Oligodendroglioma, IDH-Mutant and 1p/19q Co-deleted  Oligodendrogliomas account for ~15–20% of gliomas. They are characterized by co-deletion of 1p/19q and have IDH mutations. Oli­ godendrogliomas are classified by the WHO into grade 2 or grade 3 oligodendrogliomas (formerly anaplastic oligodendrogliomas). Oligo­ dendrogliomas have distinctive pathologic features such as perinuclear clearing—giving rise to a “fried egg” appearance—and a reticular pattern of blood vessel growth. Some tumors have both an oligoden­ droglial as well as an astrocytic component. With molecular testing, it is now clear that almost all of these mixed tumors (oligoastrocytomas) are genetically either astrocytomas or oligodendrogliomas. As a result, the diagnosis of oligoastrocytoma is now rarely made unless molecular testing is not available. Grade 2 oligodendrogliomas are generally more responsive to therapy and have a better prognosis than pure astrocytic tumors. These tumors present similarly to grade 2 astrocytomas in young adults. The tumors are nonenhancing and often partially calcified. They should be treated with surgery and, in patients with residual disease or aged >40 years, RT and chemotherapy. Targeting mutant IDH with inhibi­ tors such as vorasidenib to delay progression and transformation to higher grade may become an effective strategy in low-grade oligoden­ droglioma. Patients with oligodendrogliomas have a median survival in excess of 10 years. Grade 3 oligodendrogliomas present in the fourth and fifth decades as variably enhancing tumors. They are more responsive to therapy than grade 3 astrocytomas. Treatment involves maximal safe resection followed by RT and PCV or temozolomide chemotherapy. Median survival of patients is in excess of 10 years. Glioblastoma  Glioblastomas account for the majority of high-grade astrocytomas and are now defined by the absence of IDH mutations. With the new WHO classification, grade 2 and 3 astrocytomas without the classic histologic features of glioblastoma (necrosis and endothe­ lial proliferation) but harboring molecular features of glioblastoma FIGURE 95-2  Postgadolinium T1 MRI of a large cystic left frontal glioblastoma. (epidermal growth factor amplification, combined with whole chromo­ some 7 gain and 10 loss, or telomerase reverse transcriptase [TERT] promoter mutations) are considered molecular glioblastomas. Glioblastomas are the most common malignant primary brain tumor, with >12,000 cases diagnosed each year in the United States. Patients usually present in the sixth and seventh decades of life with headache, seizures, or focal neurologic deficits. The tumors appear as ring-enhancing masses with central necrosis and surrounding edema (Fig. 95-2). These are highly infiltrative tumors, and the areas of increased T2/FLAIR signal surrounding the main tumor mass contain invading tumor cells. Treatment involves maximal surgical resection followed by involved-field external-beam RT (6000 cGy in thirty 200-cGy fractions) with concomitant temozolomide, followed by 6 months of adjuvant temozolomide. With this regimen, median survival is increased to 15–18 months compared to only 12 months with RT alone, and 5-year survival is ~10%. Efforts to increase the dose of RT locally using brachytherapy or stereotactic radiosurgery (SRS) have failed to improve the outcome, and these treatments are not recommended. Patients whose tumor contains the DNA repair enzyme O6-methylguanine-DNA methyltransferase (MGMT) are relatively resistant to temozolomide and have a worse prognosis compared to those whose tumors contain low levels of MGMT as a result of silenc­ ing of the MGMT gene by promoter hypermethylation. Implantation of biodegradable polymers containing carmustine chemotherapy into the tumor bed after resection of the tumor or addition of tumor treat­ ing fields (scalp electrodes delivering low-intensity electric currents) produces a modest improvement in survival. For elderly patients aged >65–70 years, a hypofractionated RT regi­ men of 40 Gy over 3 weeks with temozolomide is well tolerated and likely leads to similar outcomes as the 6-week standard RT regimen. Despite optimal therapy, glioblastomas invariably recur. Treatment options for recurrent disease may include reoperation, reirradiation, and treatment with bevacizumab and standard chemotherapeutic regi­ mens. Bevacizumab, a humanized vascular endothelial growth factor (VEGF) monoclonal antibody, has activity in recurrent glioblastoma, increasing progression-free survival but not overall survival and reduc­ ing peritumoral edema and glucocorticoid use (Fig. 95-3). Immune checkpoint inhibitors have been successful in a variety of solid tumors but have failed to demonstrate substantial activity in glioblastoma. A recent phase 3 trial comparing bevacizumab with nivolumab in recur­ rent glioblastoma demonstrated an identical median overall survival CHAPTER 95 A Primary and Metastatic Tumors of the Nervous System B FIGURE 95-3  Postgadolinium T1 MRI of a recurrent glioblastoma before (A) and after (B) administration of bevacizumab. Note the decreased enhancement and mass effect. of approximately 10 months in the two arms, with similar toxicities. Treatment decisions for patients with recurrent glioblastoma must be made on an individual basis, taking into consideration such factors as previous therapy, time to relapse, performance status, and quality of life. Whenever feasible, patients should be enrolled in clinical trials. Novel therapies undergoing evaluation in patients with glioblastoma include targeted molecular agents directed at receptor tyrosine kinases and signal transduction pathways; immunotherapy using vaccines, novel checkpoint inhibitors, or chimeric antigen receptor (CAR) T cells; oncolytic viruses; antiangiogenic agents; chemotherapeutic agents that cross the blood-brain barrier more effectively than cur­ rently available drugs; and infusion of radiolabeled drugs and targeted toxins into the tumor and surrounding brain by means of convectionenhanced delivery. The most important adverse prognostic factors in patients with glioblastomas are older age, unmethylated MGMT promoter, poor Karnofsky performance status, and unresectable tumor. Gliosarcomas are a variant of glioblastoma containing both an astro­ cytic and a sarcomatous component and are treated in the same way as glioblastomas. ■ ■PEDIATRIC-TYPE DIFFUSE HIGH-GRADE GLIOMA Pediatric-type diffuse high-grade gliomas (HGGs) are clinically and biologically distinct and are further classified based on their location, which also corresponds to specific molecular alterations. These tumors are typical in younger patients, including young adults, and prior to the recognition of these specific molecular drivers, many pediatric-type HGGs, which do not harbor IDH mutations, were often diagnosed and treated as glioblastoma. Diffuse Midline Glioma, H3K27-Altered  These tumors arise from midline structures including the pons, thalamus, or spinal cord and have an infiltrative appearance, often without contrast enhance­ ment on MRI. They harbor mutations in the H3F3A gene, resulting in lysine-to-methionine substitution in amino acid residue 27 (K27M). H3K27-altered glioma can occur both in children and adults and car­ ries a poor prognosis regardless of grade. As gross total resection is not feasible in these tumors, treatment mostly consists of RT, while sys­ temic therapy options remain limited in efficacy. The median overall survival is about 1 year. Diffuse Hemispheric Glioma, H3 G34-Mutant  Another HGG that preferentially occurs in young adults is the diffuse hemispheric glioma with the histone variant H3.3 glycine to arginine or valine (H3.3-G34R/V) mutation. These tend to occur in a hemispheric loca­ tion, and the progression remains poor, with median overall survival of 18–22 months. No standard-of-care treatment exists for these tumors, which are often treated similar to GBM with RT and chemotherapy. PART 4 Oncology and Hematology ■ ■PEDIATRIC-TYPE LOW-GRADE GLIOMA While most common in pediatric patients, pediatric-type low-grade gli­ omas can also arise in young and older adults. They include avian myelo­ blastosis viral oncogene (MYB)-altered or MYB proto-oncogene like 1 (MYBL1)-altered diffuse gliomas and mitogen-activated protein kinase (MAPK)-altered diffuse gliomas (commonly v-Raf murine sarcoma viral oncogene homolog B [BRAF] or fibroblast growth factor receptor [FGFR] alterations). Gross total resection can be curative in many cases, and systemic therapy can provide durable response with oral BRAF or MAPK inhibitors when a targetable mutation or fusion is found. ■ ■CIRCUMSCRIBED ASTROCYTOMA AND OTHER GLIONEURONAL TUMORS These tumors regroup several histologies of more circumscribed tumors, with a typically more indolent natural history. Pilocytic astro­ cytomas (WHO grade 1) are the most common tumor of childhood. They occur typically in the cerebellum but may also be found elsewhere in the neuraxis, including the optic nerves and brainstem. Frequently they appear as cystic lesions with an enhancing mural nodule. Often, they have BRAF fusions or mutations. These are well-demarcated lesions that are potentially curable if they can be resected completely. Subependymal giant cell astrocytomas (SEGAs) are usually found in the ventricular wall of patients with tuberous sclerosis, discussed later. Gangliogliomas and pleomorphic xanthoastrocytomas occur in young adults. They behave as more indolent forms of grade 1 gliomas and are usually treated with surgery. Frequently they will have BRAF V600E mutations, which can be targeted with BRAF inhibitors. ■ ■EPENDYMOMAS Ependymomas are tumors derived from ependymal cells that line the ventricular surface. They arise in three different compartments and are classified according to location as supratentorial, posterior fossa, or spinal ependymomas. Further molecular stratification within each location (supratentorial ependymoma with ZFTA or YAP1 oncogenic fusion; posterior fossa A or posterior fossa B; and spinal with or with­ out MYCN amplification) and grading can help guide management. Children typically present with posterior fossa ependymoma followed by supratentorial ependymoma. Although adults can have intracranial ependymomas, they occur more commonly in the spine, especially in the filum terminale of the spinal cord where they have a myxopapillary histology. Ependymomas that can be completely resected are poten­ tially curable. Partially resected ependymomas will recur and require irradiation. The less common anaplastic ependymoma is more aggres­ sive and is treated with resection and RT; chemotherapy has limited efficacy. Subependymomas are slow-growing benign lesions arising in the wall of ventricles that often do not require treatment. ■ ■PRIMARY CENTRAL NERVOUS SYSTEM LYMPHOMA Primary central nervous system lymphoma (PCNSL) is a rare nonHodgkin’s lymphoma accounting for <3% of primary brain tumors. For unclear reasons, its incidence is increasing, particularly in immu­ nocompetent, older individuals. PCNSL in immunocompetent patients is usually a diffuse large B-cell lymphoma. Immunocompromised patients, especially those infected with the human immunodeficiency virus (HIV) or organ transplant recipients, are at risk for PCNSL that is typically large cell with immunoblastic and more aggressive features. Epstein-Barr virus (EBV) plays an important role in the pathogenesis of PCNSL in this population. These patients are usually severely immunocompromised, with CD4 counts of <50/mL. Immunocompetent patients with PCNSL are older (median age, 60 years) than those with HIV-related PCNSL (median age, 31 years). PCNSL usually presents as a mass lesion, with neuropsychiatric symptoms, lateralizing signs, or seizures. Ocular and leptomeningeal involvement each occur in 15–20% of patients, and involvement of these compartments may be asymptomatic. Rarely, it may present as isolated ocular lymphoma or as primary leptomeningeal lymphoma. When restricted to the leptomeninges, it may present as a subacute or chronic meningitis that causes progressive cranial and spinal nerve dysfunction. CSF cytologic examination or flow cytometry is required to establish the diagnosis. On contrast-enhanced MRI, PCNSL usually appears as a densely enhancing tumor (Fig. 95-4). Immunocompetent patients have solitary lesions more often than immunosuppressed patients. Frequently, there is involvement of the basal ganglia, corpus callosum, or periventricular region. Stereotactic biopsy is necessary to obtain a histologic diagno­ sis. Whenever possible, glucocorticoids should be withheld until after the biopsy has been obtained because they have a cytolytic effect on FIGURE 95-4  Postgadolinium T1 MRI demonstrating a large bifrontal primary central nervous system lymphoma (PCNSL). The periventricular location and diffuse enhancement pattern are characteristic of lymphoma. lymphoma cells and may lead to nondiagnostic tissue. In addition, patients should be tested for HIV, and the extent of disease should be assessed by performing PET or CT of the body, MRI of the spine, CSF analysis, and slit-lamp examination of the eye. Bone marrow biopsy and testicular ultrasound are occasionally performed. TREATMENT Primary Central Nervous System Lymphoma PCNSL is more sensitive to glucocorticoids, chemotherapy, and RT than other primary brain tumors. Durable complete responses and long-term survival are possible with these treatments. High-dose methotrexate, a folate antagonist that interrupts DNA synthesis, produces response rates ranging from 35 to 80% and median survival of up to 50 months. The combination of methotrexate with other chemotherapeutic agents such as cytarabine increases the response rate to 70–100%. The addition of whole-brain RT (WBRT) to methotrexate-based chemotherapy prolongs progres­ sion-free survival but not overall survival, but it is associated with delayed neurotoxicity, especially in patients aged >60 years. As a result, full-dose RT is frequently omitted, but there may be a role for reduced-dose RT. The anti-CD20 monoclonal antibody rituximab is often incorporated into the chemotherapy regimen, although there are studies questioning its benefit. For some patients, highdose chemotherapy with autologous stem cell rescue may offer the best chance of preventing relapse. At least 50% of patients will eventually develop recurrent disease. Treatment options include RT for patients who have not had prior irradiation, retreatment with methotrexate, and other chemotherapeutic agents such as temo­ zolomide and pemetrexed. High-dose chemotherapy with autolo­ gous stem cell rescue may be appropriate in selected patients with relapsed disease. Bruton’s tyrosine kinase (BTK) inhibitors such as ibrutinib, immunomodulatory drugs such as pomalidomide and lenalidomide, and immune checkpoint inhibitors have shown promising preliminary activity and are being evaluated in clinical trials, as are CAR-T cells. PCNSL IN IMMUNOCOMPROMISED PATIENTS PCNSL in immunocompromised patients often produces multiple ring-enhancing lesions that can be difficult to differentiate from metastases or infections such as toxoplasmosis. The diagnosis is usually established by examination of the CSF for cytology and EBV DNA; toxoplasmosis serologic testing; brain PET imaging for hypermetabolism of the lesions, which, although nonspecific, can be consistent with tumor; and, if necessary, brain biopsy. Since the advent of highly active antiretroviral drugs, the incidence of HIV-related PCNSL has declined. These patients are preferably treated with high-dose methotrexate-based regimens and initiation of highly active antiretroviral therapy; WBRT is reserved for those who cannot tolerate systemic chemotherapy. In organ transplant recipients, reduction of immunosuppression may improve outcome. ■ ■MEDULLOBLASTOMA Medulloblastomas are the most common malignant brain tumor of childhood, accounting for ~20% of all primary CNS tumors among chil­ dren. They arise from granule cell progenitors or from multipotent pro­ genitors from the ventricular zone. Approximately 5% of children with medulloblastoma have an inherited syndrome, such as Gorlin, Turcot, or Li-Fraumeni, which predisposes to the development of medulloblas­ toma. Histologically, medulloblastomas are highly cellular tumors with abundant dark staining, round nuclei, and rosette formation (HomerWright rosettes). In the 2016 WHO pathologic classification, they have been divided into four molecular subgroups: (1) WNT-activated (pri­ marily affects children and has the best outcome); (2) SHH-activated (affects adults, infants, and children, with the younger patients having the better outcome and adults doing poorly); (3) non-WNT/non-SHH, group 3 (frequently has disseminated CNS disease at diagnosis and has the worst outcome); and (4) non-WNT/non-SHH, group 4 (30% have metastases at diagnosis, but 5-year progression-free survival is 95%). Regardless of subtype, patients present with headache, ataxia, and signs of brainstem involvement. On MRI, they appear as densely enhanc­ ing tumors in the posterior fossa, sometimes associated with hydro­ cephalus. Treatment involves maximal surgical resection, craniospinal irradiation, and chemotherapy with agents such as cisplatin, lomustine, cyclophosphamide, and vincristine. Approximately 70% of patients overall have long-term survival but usually at the cost of significant neu­ rocognitive impairment. A major goal of current research is to improve survival while minimizing long-term complications, and clinical trials are now being designed for specific molecular subgroups. ■ ■PINEAL REGION TUMORS A large variety of tumors can arise in the region of the pineal gland. These typically present with headache, visual symptoms, and hydroceph­ alus. Patients may have Parinaud’s syndrome characterized by impaired upgaze and accommodation. Some pineal tumors such as pineocytomas and benign teratomas can be treated by surgical resection. Germinomas respond to irradiation, whereas pineoblastomas and nongerminomatous germ cell tumors require craniospinal RT and chemotherapy. EXTRINSIC “BENIGN” TUMORS CHAPTER 95 ■ ■MENINGIOMA Meningiomas are diagnosed with increasing frequency as more people undergo neuroimaging for various indications. They are now the most common primary brain tumor, accounting for ~35% of the total. Their incidence increases with age. They tend to be more common in women and in patients with neurofibromatosis type 2 (NF2). They also occur more commonly in patients with a history of cranial irradiation. Primary and Metastatic Tumors of the Nervous System Meningiomas arise from the dura mater and are composed of neoplastic meningothelial (arachnoidal cap) cells. They are most com­ monly located over the cerebral convexities, especially adjacent to the sagittal sinus, but they can also occur in the skull base and along the dorsum of the spinal cord. Meningiomas are classified by the WHO into three histologic grades of increasing aggressiveness: grade I (benign), grade II (atypical), and grade III (malignant). Many meningiomas are found incidentally following neuroimaging for unrelated reasons. They can also present with headaches, seizures, or focal neurologic deficits. On imaging studies, they have a charac­ teristic appearance usually of a densely enhancing extra-axial tumor arising from the dura (Fig. 95-5). Typically they have a dural tail, con­ sisting of thickened, enhanced dura extending like a tail from the mass. The main differential diagnosis of meningioma is a dural metastasis. If the meningioma is small and asymptomatic, no intervention is necessary and the lesion can be observed with serial MRI studies. Larger, symptomatic lesions should be resected. If complete resection is achieved, the patient is cured. Incompletely resected tumors tend to recur, although the rate of recurrence can be very slow with grade I tumors. Tumors that cannot be resected or can only be partially removed may benefit from external-beam RT or SRS. These treatments may also be helpful in patients whose tumor has recurred after surgery. Hormonal therapy and chemotherapy are currently unproven. Rarer tumors that resemble meningiomas include hemangiopericy­ tomas and solitary fibrous tumors. Since they share similar molecular alterations (NAB2-STAT6 fusion), the 2016 WHO classification intro­ duced the combined term solitary fibrous tumor/hemangiopericytoma for this entity. These tumors are treated with surgery and RT but have a higher propensity to recur locally or metastasize systemically. ■ ■SCHWANNOMA These are generally benign tumors arising from the Schwann cells of cranial and spinal nerve roots. The most common schwannomas, termed vestibular schwannomas or acoustic neuromas, arise from the vestibular portion of the eighth cranial nerve and account for ~9% of primary brain tumors. Patients with NF2 have a high incidence of vestibular schwannomas that are frequently bilateral. Schwannomas arising from other cranial nerves, such as the trigeminal nerve (cranial nerve V), occur with much lower frequency. Neurofibromatosis type 1 PART 4 Oncology and Hematology FIGURE 95-5  Postgadolinium T1 MRI demonstrating multiple meningiomas along the falx and left parietal cortex. (NF1) is associated with an increased incidence of schwannomas of the spinal nerve roots. Vestibular schwannomas may be found incidentally on neuroim­ aging or present with progressive unilateral hearing loss, dizziness, tinnitus, or, less commonly, symptoms resulting from compression of the brainstem and cerebellum. On MRI, they appear as densely enhancing lesions, enlarging the internal auditory canal and often extending into the cerebellopontine angle (Fig. 95-6). The differential diagnosis includes meningioma. Very small, asymptomatic lesions can be observed with serial MRIs. Larger lesions should be treated with surgery or SRS. The optimal treatment will depend on the size of the tumor, symptoms, and the patient’s preference. In patients with small vestibular schwannomas and relatively intact hearing, early surgical intervention increases the chance of preserving hearing. FIGURE 95-6  Postgadolinium MRI of a right vestibular schwannoma. The tumor can be seen to involve the internal auditory canal. ■ ■PITUITARY TUMORS These are discussed in detail in Chap. 392. ■ ■CRANIOPHARYNGIOMAS Craniopharyngiomas are rare, usually suprasellar, partially calcified, solid, or mixed solid-cystic benign tumors that arise from remnants of Rathke’s pouch. They have a bimodal distribution, occurring pre­ dominantly in children but also between the ages of 55 and 65 years. They present with headaches, visual impairment, and impaired growth in children and hypopituitarism in adults. Treatment involves surgery, RT, or a combination of the two. The papillary subtype of craniopha­ ryngiomas often has BRAF V600E mutations and can be treated with RAF/MEK inhibitors. ■ ■OTHER BENIGN TUMORS Epidermoid Cysts  These consist of squamous epithelium sur­ rounding a keratin-filled cyst. They are usually found in the cerebel­ lopontine angle and the intrasellar and suprasellar regions. They may present with headaches, cranial nerve abnormalities, seizures, or hydrocephalus. MRI demonstrates an extra-axial lesion with charac­ teristics that are similar to CSF but have restricted diffusion. Treatment involves surgical resection. Dermoid Cysts  Like epidermoid cysts, dermoid cysts arise from epithelial cells that are retained during closure of the neural tube. They contain both epidermal and dermal structures such as hair follicles, sweat glands, and sebaceous glands. Unlike epidermoid cysts, these tumors usually have a midline location. They occur most frequently in the posterior fossa, especially the vermis, fourth ventricle, and supra­ sellar cistern. On MRI, dermoid cysts resemble lipomas, demonstrating T1 hyperintensity and variable signal on T2. Symptomatic dermoid cysts can be treated with surgery. Colloid Cysts  These usually arise in the anterior third ventricle and may present with headaches, hydrocephalus, and, very rarely, sud­ den death. Surgical resection is curative, or a third ventriculostomy may relieve the obstructive hydrocephalus and be sufficient therapy. NEUROCUTANEOUS SYNDROMES (PHAKOMATOSES) A number of genetic disorders are characterized by cutaneous lesions and an increased risk of brain tumors. Most of these disorders have an autosomal dominant inheritance with variable penetrance. ■ ■NEUROFIBROMATOSIS TYPE 1 (von RECKLINGHAUSEN’S DISEASE) NF1 is an autosomal dominant disorder with variable penetrance and an incidence of ~1 in 2600–3000. Approximately one-half of cases are familial; the remainder are caused by new mutations arising in patients with unaffected parents. The NF1 gene is located on chromo­ some 17q11.2 and encodes neurofibromin, a guanosine triphosphatase (GTPase) activating protein (GAP) that is a negative regulator of the RAS–mitogen-activated protein (MAP) kinase signaling pathway, which includes the downstream kinase MEK. It is a classic tumor suppressor, and biallelic loss can result in a variety of nervous system tumors including neurofibromas, plexiform neurofibromas, optic nerve gliomas, astrocytomas, and meningiomas. In addition to neuro­ fibromas, which appear as multiple, soft, rubbery cutaneous tumors, other cutaneous manifestations of NF1 include café-au-lait spots and axillary freckling. NF1 is also associated with hamartomas of the iris termed Lisch nodules, pheochromocytomas, pseudoarthrosis of the tibia, scoliosis, epilepsy, and intellectual disability. The MEK inhibi­ tor selumetinib has activity against inoperable plexiform neurofibro­ mas and is the only treatment that targets the dysregulated signaling pathway. ■ ■NEUROFIBROMATOSIS TYPE 2 NF2 is less common than NF1, with an incidence of 1 in 25,000– 40,000. It is an autosomal dominant disorder with full penetrance. As with NF1, approximately one-half of cases arise from new mutations. The NF2 gene on 22q encodes a cytoskeletal protein, merlin (moesin, ezrin, radixin-like protein), that functions as a tumor suppressor. NF2 is characterized by bilateral vestibular schwannomas in >90% of patients, multiple meningiomas, and spinal ependymomas and astro­ cytomas. Treatment of bilateral vestibular schwannomas can be chal­ lenging because the goal is to preserve hearing for as long as possible. These patients may also have diffuse schwannomatosis that may affect the cranial, spinal, or peripheral nerves; posterior subcapsular lens opacities; and retinal hamartomas. ■ ■TUBEROUS SCLEROSIS (BOURNEVILLE DISEASE) This is an autosomal dominant disorder with an incidence of ~1 in 5000–10,000 live births. It is caused by mutations in either the TSC1 gene, which encodes a protein termed hamartin, or the TSC2 gene, which encodes the protein tuberin. Hamartin forms a complex with tuberin, which inhibits cellular signaling through the mammalian tar­ get of rapamycin (mTOR), and acts as a negative regulator of the cell cycle. Patients with tuberous sclerosis may have seizures, intellectual disability, adenoma sebaceum (facial angiofibromas), shagreen patch, hypomelanotic macules, periungual fibromas, renal angiomyolipomas, and cardiac rhabdomyomas. These patients have an increased inci­ dence of subependymal nodules, cortical tubers, and SEGAs. Patients frequently require anticonvulsants for seizures. SEGAs do not always require therapeutic intervention, but the most effective therapy is with the mTOR inhibitors sirolimus or everolimus, which often decrease seizures as well as SEGA size. TUMORS METASTATIC TO THE BRAIN Brain metastases arise from hematogenous spread and frequently origi­ nate from a lung primary or are associated with pulmonary metastases. Most metastases develop at the gray matter–white matter junction in the watershed distribution of the brain where intravascular tumor cells lodge in terminal arterioles. The distribution of metastases in the brain approximates the proportion of blood flow such that ~85% of all metastases are supratentorial and 15% occur in the posterior fossa. The most common sources of brain metastases are lung and breast carcino­ mas; melanoma has the greatest propensity to metastasize to the brain, being found in 80% of patients at autopsy (Table 95-4). Other tumor types such as ovarian and esophageal carcinoma rarely metastasize to the brain. Prostate and breast cancers also have a propensity to metas­ tasize to the dura and can mimic meningioma. Leptomeningeal metas­ tases are common from hematologic malignancies and also breast and lung cancers. Spinal cord compression primarily arises in patients with prostate and breast cancer, tumors with a strong propensity to metas­ tasize to the axial skeleton. ■ ■DIAGNOSIS OF METASTASES Brain metastases are best visualized on MRI, where they usually appear as well-circumscribed lesions (Fig. 95-7). The amount of perilesional edema can be highly variable, with large lesions causing minimal edema and sometimes very small lesions causing extensive edema. Enhance­ ment may be in a ring pattern or diffuse. Occasionally, intracranial TABLE 95-4  Frequency of Nervous System Metastases for Common Primary Tumors BRAIN (%) LM (%) ESCC (%) Lung Breast Melanoma Prostate GIT — Renal Lymphoma <1 Sarcoma Other — Abbreviations: ESCC, epidural spinal cord compression; GIT, gastrointestinal tract; LM, leptomeningeal metastases. CHAPTER 95 A Primary and Metastatic Tumors of the Nervous System B FIGURE 95-7  Postgadolinium T1 MRI of multiple brain metastases from non-smallcell lung cancer involving the right frontal (A) and right cerebellar (B) hemispheres. Note the diffuse enhancement pattern and absence of central necrosis. metastases will hemorrhage; melanoma, thyroid, and kidney cancer have the greatest propensity to hemorrhage, but the most common cause of a hemorrhagic metastasis is lung cancer because it accounts for the majority of brain metastases. The radiographic appearance of brain metastasis is nonspecific, and similar-appearing lesions can occur with infection including brain abscesses, demyelinating lesions, sarcoidosis, radiation necrosis in a previously treated patient, or a primary brain tumor that may be a second malignancy in a patient with systemic cancer. Biopsy is rarely necessary for diagnosis because imaging alone in the appropriate clinical situation usually suffices. However, in ~10% of patients, a systemic cancer may present with a brain metastasis, and if there is not an easily accessible systemic site to biopsy, a brain lesion must be removed for diagnostic purposes. TREATMENT Tumors Metastatic to the Brain DEFINITIVE TREATMENT The number and location of brain metastases often determine the therapeutic options. The patient’s overall condition and current or potential control of systemic disease are also major determinants. Brain metastases are single in approximately one-half of patients and multiple in the other half. RADIATION THERAPY The standard treatment for brain metastases has previously been WBRT usually administered to a total dose of 3000 cGy in 10 frac­ tions. This affords rapid palliation, and ~80% of patients improve with glucocorticoids and RT. However, it is not curative, is associated with neurocognitive toxicity, and produces median survival of only 4–6 months. Hippocampal avoidance during WBRT can preserve cognitive function without increasing the risk of an intracranial relapse. The use of WBRT has declined with the development of more effective systemic options and access to SRS. If feasible, SRS has become the primary radiation oncology approach to brain metastases. It can be delivered through a variety of equally effective techniques including the gamma knife, linear accelerator, proton beam, or CyberKnife, all of which can deliver highly focused doses of RT, usually in a single fraction. SRS can effectively sterilize the visible lesions and afford local disease control in 80–90% of patients. Some patients have been cured of their brain metastases using SRS, whereas this is distinctly rare with WBRT. Traditionally SRS was used only for patients with 1–3 metastases, but recent data suggest that SRS can effectively treat 10 or more lesions. It is, however, confined to lesions of ≤3 cm and is most effective in metastases of ≤1 cm. The addition of WBRT to SRS improves disease control in the nervous system but does not prolong survival and thus is rarely employed. PART 4 Oncology and Hematology SURGERY Randomized controlled trials have demonstrated that surgical extir­ pation of a single brain metastasis followed by WBRT is superior to WBRT alone. Removal of two lesions or a single symptomatic mass, particularly if compressing the ventricular system, can also be useful. This is particularly important in patients who have highly radioresistant lesions such as renal carcinoma. Surgical resection can produce rapid amelioration of symptoms, improve control of edema, and result in prolonged survival. WBRT administered after complete resection of a brain metastasis improves disease control but does not prolong survival. There is increasing use of focal RT or even SRS to a resected cavity, especially if there is concern that tumor has been left behind, but most avoid postoperative WBRT because of its cognitive effects. CHEMOTHERAPY Chemotherapy and targeted therapy are becoming increasingly useful for brain metastases. Metastases from tumor types that are highly chemosensitive, such as germ cell tumors or small-cell lung cancer, may respond to chemotherapeutic regimens chosen accord­ ing to the underlying malignancy. Increasingly, data demonstrate responsiveness of brain metastases to targeted therapeutics, such as for patients with lung cancer harboring EGFR mutations that sensitize them to EGFR inhibitors. Immunotherapy is also effective against those primary tumors that are sensitive to this approach, such as melanoma. Antiangiogenic agents such as bevacizumab are effective in the treatment of CNS metastases in those primary tumors for which it is approved. LEPTOMENINGEAL METASTASES Leptomeningeal metastases are also described as carcinomatous men­ ingitis, meningeal carcinomatosis, or, in the case of specific tumors, leukemic or lymphomatous meningitis. Among the hematologic malignancies, acute leukemias most commonly metastasize to the subarachnoid space, followed in frequency by aggressive diffuse lym­ phomas. Among solid tumors, breast and lung carcinomas and mela­ noma most frequently spread in this fashion. Tumor cells reach the subarachnoid space via the arterial circulation or occasionally through retrograde flow in venous systems that drain metastases along the bony spine or cranium. In addition, leptomeningeal metastases may develop as a direct consequence of prior brain metastases and occur in almost 40% of patients who have a metastasis resected from the cerebellum. ■ ■CLINICAL FEATURES Leptomeningeal metastases are characterized by multilevel symptoms and signs along the neuraxis. Combinations of lumbar and cervi­ cal radiculopathies, cranial neuropathies, seizures, confusion, and encephalopathy from hydrocephalus or raised intracranial pressure can be present. Focal deficits such as hemiparesis or aphasia are rarely due to leptomeningeal metastases unless there is direct brain infiltra­ tion. New-onset limb pain in patients with breast cancer, lung cancer, or melanoma should prompt consideration of leptomeningeal spread. ■ ■LABORATORY AND IMAGING DIAGNOSIS Leptomeningeal metastases are particularly challenging to diagnose because identification of tumor cells in the subarachnoid compart­ ment may be elusive. MRI can be definitive when there are clear tumor nodules adherent to the cauda equina or spinal cord, enhancing cranial nerves, or subarachnoid enhancement on brain imaging (Fig. 95-8). Imaging is diagnostic in ~75% of patients and is more often positive in patients with solid tumors. Demonstration of tumor cells in the CSF is definitive and often considered the gold standard. However, CSF cytologic examination is positive in only 50% of patients on the first lumbar puncture and still misses 10% after three CSF samples. New technologies, such as rare cell capture, enhance identification of tumor cells in the CSF; molecular profiling of the CSF can also identify tumor-specific mutations, indicating malignancy in the leptomeninges. CSF cytologic examination is most useful in hematologic malignancies, especially when combined with flow cytometry to identify a clonal population. Accompanying CSF abnormalities include an elevated protein concentration and an elevated white blood cell count; hypo­ glycorrhachia is noted in <25% of patients but is useful when present. Identification of tumor markers may be helpful in some solid tumors. TREATMENT Leptomeningeal Metastases The treatment of leptomeningeal metastasis is palliative because there is no curative therapy. RT to the symptomatically involved areas, such as skull base for cranial neuropathy, can relieve pain and sometimes improve function. Craniospinal irradiation (CSI) was previously avoided because it has significant toxicity with myelosup­ pression and gastrointestinal irritation as well as limited effectiveness. However, recent data on proton beam CSI suggest better disease con­ trol with fewer systemic toxicities. Systemic chemotherapy, targeted therapeutics, and immunotherapy have all demonstrated limited efficacy in the appropriate setting. Alternatively, intrathecal chemo­ therapy can be effective, particularly in hematologic malignancies. This is optimally delivered through an intraventricular cannula (Ommaya reservoir) rather than by lumbar puncture. Few drugs can be delivered safely into the subarachnoid space, and they have a limited spectrum of antitumor activity, perhaps accounting for the relatively poor response to this approach, particularly in solid tumors. In addition, impaired CSF flow dynamics can compromise intrathecal drug delivery. Surgery has a limited role in leptomen­ ingeal metastasis. A ventriculoperitoneal shunt can relieve raised intracranial pressure but complicates the use of intrathecal drugs. EPIDURAL METASTASIS Epidural metastasis occurs in 3–5% of patients with a systemic malig­ nancy and causes neurologic compromise by compressing the spinal cord or cauda equina. The most common cancers that metastasize to FIGURE 95-9  Postgadolinium T1 MRI showing circumferential epidural tumor around the thoracic spinal cord from esophageal cancer. A B FIGURE 95-8  Postgadolinium MRI images of extensive leptomeningeal metastases from breast cancer. Nodules along the dorsal surface of the spinal cord (A) and cauda equina (B) are seen. the epidural space are those malignancies that spread to bone, such as breast and prostate. Lymphoma can cause bone involvement and com­ pression, but it can also invade an intervertebral foramen and cause spinal cord compression without bone destruction. The thoracic spine is affected most commonly, followed by the lumbar and then cervical spine. ■ ■CLINICAL FEATURES Back pain is the presenting symptom of epidural metastasis in virtu­ ally all patients; the pain may precede neurologic findings by weeks or months. The pain is usually exacerbated by lying down; by contrast, arthritic pain is often relieved by recumbency. Leg weakness is seen in ~50% of patients, as is sensory dysfunction. Sphincter problems are present in ~25% of patients at diagnosis. CHAPTER 95 ■ ■DIAGNOSIS Diagnosis is established by imaging, preferably with an MRI of the entire spine (Fig. 95-9). Any patient with cancer who has severe back pain should undergo an MRI. Plain films, bone scans, or even CT scans may show bone metastases, but only MRI can reliably delineate epidural tumor. For patients unable to have an MRI, CT myelography should be performed to outline the epidural space. The differen­ tial diagnosis of epidural tumor includes epidural abscess, acute or chronic hematomas, epidural lipomatosis, and, rarely, extramedullary hematopoiesis. Primary and Metastatic Tumors of the Nervous System TREATMENT Epidural Metastasis Epidural metastasis requires immediate treatment. A randomized controlled trial demonstrated the superiority of surgical resection followed by RT compared to RT alone. However, patients must be able to tolerate surgery, and the surgical procedure of choice is a complete removal of the mass, which is typically anterior to the spinal canal, necessitating an extensive approach and resection. Otherwise, RT is the mainstay of treatment and can be used for patients with radiosensitive tumors, such as lymphoma, or for those unable to undergo surgery. SRS or stereotactic body radiotherapy is increasingly being used, especially for radioresistant tumor types or for reirradiation. Chemotherapy is rarely used for epidural metas­ tasis unless the patient has minimal to no neurologic deficit and a highly chemosensitive tumor such as lymphoma or germinoma. Patients generally fare well if treated before there is a severe neu­ rologic deficit. Recovery from paraparesis is better after surgery than with RT alone, but survival is often short due to widespread metastatic tumor. NEUROLOGIC TOXICITY OF THERAPY ■ ■TOXICITY FROM RADIOTHERAPY RT can cause a variety of toxicities in the CNS. These are usually described based on their relationship in time to the administration of RT: acute (occurring within days of RT), early delayed (months), or late delayed (years). In general, the acute and early delayed syndromes resolve and do not result in persistent deficits, whereas the late delayed toxicities are usually permanent and sometimes progressive. Acute Toxicity  Acute cerebral toxicity may occur during RT to the brain. RT can cause a transient disruption of the blood-brain barrier, resulting in edema and elevated intracranial pressure. This is usually manifest as headache, lethargy, nausea, and vomiting and can be both prevented and treated with the administration of glucocorticoids. Early Delayed Toxicity  Early delayed toxicity is usually apparent weeks to months after completion of cranial irradiation and is likely due to focal demyelination. Clinically it may be asymptomatic or take the form of worsening or reappearance of a preexisting neurologic deficit. At times, a contrast-enhancing lesion can be seen on MRI/CT that can mimic the tumor for which the patient received the RT. For patients with a malignant glioma, this has been described as “pseu­ doprogression” because it mimics tumor recurrence on MRI, but it represents inflammation and necrotic debris engendered by effective therapy. This is seen with increased frequency when chemotherapy, particularly temozolomide, is given concurrently with RT. Pseudopro­ gression can resolve on its own or, if very symptomatic, may require glucocorticoids, resection, or bevacizumab. In the spinal cord, early delayed RT toxicity is manifest as a Lher­ mitte symptom with paresthesias of the limbs or along the spine when the patient flexes the neck. Although frightening, it is benign, resolves on its own, and does not portend more serious problems. PART 4 Oncology and Hematology Late Delayed Toxicity  Late delayed toxicities are the most serious because they are often irreversible and cause severe neurologic deficits. In the brain, late toxicities can take several forms, the most common of which include radiation necrosis and leukoencephalopathy. Radiation necrosis is a focal mass of necrotic tissue that is contrast enhancing on CT/MRI and may be associated with significant edema. This may appear identical to pseudoprogression but is seen months to years after RT and is always symptomatic. Clinical symptoms and signs include seizures and findings referable to the location of the necrotic mass. The necrosis is caused by the effect of RT on cerebral vasculature with fibrinoid necrosis and occlusion of blood vessels. It can mimic tumor radiographically, but unlike tumor, it is typically hypometabolic on a PET scan and has reduced cerebral blood volume on perfusion MR sequences. It may require resection for diagnosis and treatment unless it can be managed with glucocorticoids. There are reports of improve­ ment with bevacizumab and laser interstitial thermal therapy. Leukoencephalopathy is seen most commonly after WBRT as opposed to focal RT. On T2 or FLAIR MR sequences, there is dif­ fusely increased signal seen throughout the hemispheric white matter, often bilaterally and symmetrically. There tends to be a periventricular predominance that may be associated with atrophy and ventricular enlargement. Clinically, patients develop cognitive impairment, a gait disorder, and later urinary incontinence, all of which can progress over time. These symptoms mimic those of normal pressure hydrocephalus, and placement of a ventriculoperitoneal shunt can improve function in some patients but does not reverse the deficits completely. Increased age is a risk factor for leukoencephalopathy but not for radiation necro­ sis. Necrosis appears to depend on an unidentified predisposition. Other late neurologic toxicities include endocrine dysfunction if the pituitary or hypothalamus was included in the RT port. An RT-induced neoplasm can occur many years after therapeutic RT for either a prior CNS or a head and neck tumor; accurate diagnosis requires surgical resection or biopsy. In addition, RT causes accelerated atherosclerosis, which can cause stroke either from intracranial vascular disease or carotid plaque from neck irradiation. The peripheral nervous system is relatively resistant to RT toxici­ ties. Peripheral nerves are rarely affected by RT, but the plexus is more vulnerable. Plexopathy develops more commonly in the brachial than in the lumbosacral distribution. It must be differentiated from tumor progression in the plexus, which is usually visualized by CT/MRI or PET scan demonstrating tumor infiltrating the region. Clinically, tumor progression is usually painful, whereas RT-induced plexopathy is painless. Radiation plexopathy is also more commonly associated with lymphedema and myokymia of the affected limb. Sensory loss and weakness are seen in both. TABLE 95-5  Neurologic Toxicities Caused by Agents Commonly Used in Patients with Cancer Acute encephalopathy (delirium)   Methotrexate (high-dose IV, IT)   Cisplatin   Vincristine   Asparaginase   Procarbazine   5-Fluorouracil (± levamisole)   Cytarabine (high-dose)   Nitrosoureas (high-dose or arterial)   Ifosfamide   Etoposide (high-dose)   Bevacizumab (PRES)   CAR-T cells Chronic encephalopathy (dementia)   Methotrexate   Carmustine   Cytarabine   Fludarabine Visual loss   Tamoxifen   Gallium nitrate   Cisplatin   Fludarabine Cerebellar dysfunction/ataxia   5-Fluorouracil (± levamisole)   Cytarabine   Procarbazine Seizures   Methotrexate   Etoposide (high-dose)   Cisplatin   Vincristine   Asparaginase   Nitrogen mustard   Carmustine   Dacarbazine (intraarterial or high-dose)   Busulfan (high-dose) Myelopathy (IT drugs)   Methotrexate   Cytarabine   Thiotepa Peripheral neuropathy   Vinca alkaloids   Cisplatin   Procarbazine   Etoposide   Teniposide   Cytarabine   Taxanes   Suramin   Bortezomib Abbreviations: CAR, chimeric antigen receptor; IT, intrathecal; IV, intravenous; PRES, posterior reversible encephalopathy syndrome. ■ ■TOXICITY FROM CHEMOTHERAPY Neurotoxicity is second to myelosuppression as the dose-limiting tox­ icity of chemotherapeutic agents (Table 95-5). Chemotherapy causes peripheral neuropathy from many commonly used agents, and the type of neuropathy can vary depending on the drug. Vincristine causes paresthesias but little sensory loss and is associated with motor dys­ function, autonomic impairment (frequently ileus), and, rarely, cranial nerve compromise. Cisplatin causes large-fiber sensory loss resulting in sensory ataxia but little cutaneous sensory loss and no weakness. The taxanes also cause a predominately sensory neuropathy. Agents such as bortezomib and thalidomide also cause neuropathy. Sometimes a severe neuropathy emerges after multiple neurotoxic agents have been used together or in sequence. Encephalopathy and seizures are common toxicities from che­ motherapeutic drugs. Ifosfamide can cause a severe encephalopathy, which is reversible with discontinuation of the drug. Fludarabine also causes a severe global encephalopathy that may be permanent. Beva­ cizumab and other anti-VEGF agents can cause posterior reversible encephalopathy syndrome. Cisplatin can cause hearing loss and less frequently vestibular dysfunction. Immunotherapy with monoclonal antibodies such as ipilimumab or nivolumab can cause an autoimmune hypophysitis, Guillain-Barré syndrome, or an autoimmune encephali­ tis. CAR-T cells frequently cause a reversible encephalopathy due to an immune effector cell–associated neurotoxicity syndrome (Chap. 318). ■ ■FURTHER READING Aizer AA et al: Brain metastases: A Society for Neuro-Oncology (SNO) consensus review on current management and future direc­ tions. Neuro Oncol 24:1613, 2022. Grommes C et al: Comprehensive approach to diagnosis and treatment of newly diagnosed primary CNS lymphoma. Neuro Oncol 21:296, 2019. # 25 - 96 Soft Tissue and Bone Sarcomas and Bone Metastases ### 96 Soft Tissue and Bone Sarcomas and Bone Metastases Lamba N et al: Epidemiology of brain metastases and leptomeningeal disease. Neuro Oncol 23:1447, 2021. Louis DN et al: The 2021 WHO classification of tumors of the central nervous system: A summary. Neuro-Oncology 23:1231, 2021. Mellinghoff IK et al: Vorasidenib in IDH1- or IDH2-mutant lowgrade glioma. N Engl J Med 389:589, 2023. Ostrom QT et al: CBTRUS statistical report: Primary brain and other central nervous system tumors diagnosed in the United States in 2016-2020. Neuro Oncol 25:iv1-iv99, 2023. Schiff D et al: Recent developments and future directions in adult lower-grade gliomas: Society for Neuro-Oncology (SNO) and Euro­ pean Association of Neuro-Oncology (EANO) consensus. Neuro Oncol 21:837, 2019. Wen PY et al: Glioblastoma in adults: A Society for Neuro-Oncology (SNO) and European Society of Neuro-Oncology (EANO) consensus review on current management and future directions. Neuro Oncol 22:1073, 2020. Shreyaskumar R. Patel Soft Tissue and Bone Sarcomas and Bone Metastases Sarcomas are rare (<1% of all malignancies) mesenchymal neoplasms that arise in bone and soft tissues. These tumors are usually of meso­ dermal origin, although a few are derived from neuroectoderm, and they are biologically distinct from the more common epithelial malig­ nancies. Sarcomas affect all age groups; 15% are found in children <15 years of age, and 40% occur after age 55 years. Sarcomas are one of the most common solid tumors of childhood and are the fifth most common cause of cancer deaths in children. Sarcomas may be divided into two groups, those derived from bone and those derived from soft tissues. SOFT TISSUE SARCOMAS Soft tissues include muscles, tendons, fat, fibrous tissue, synovial tissue, vessels, and nerves. Approximately 60% of soft tissue sarcomas arise in the extremities, with the lower extremities involved three times as often as the upper extremities. Thirty percent arise in the trunk, with the ret­ roperitoneum accounting for 40% of all trunk lesions. The remaining 10% arise in the head and neck. ■ ■INCIDENCE Approximately 13,400 new cases of soft tissue sarcomas occurred in the United States in 2023. The annual age-adjusted incidence is 3 per 100,000 population, but the incidence varies with age. Soft tissue sarco­ mas constitute 0.7% of all cancers in the general population and 6.5% of all cancers in children. ■ ■EPIDEMIOLOGY Malignant transformation of a benign soft tissue tumor is extremely rare, with the exception that malignant peripheral nerve sheath tumors (neurofibrosarcoma, malignant schwannoma) can arise from neuro­ fibromas in patients with neurofibromatosis. Several etiologic factors have been implicated in soft tissue sarcomas. Environmental Factors  Trauma or previous injury is rarely involved, but sarcomas can arise in scar tissue resulting from a prior operation, burn, fracture, or foreign body implantation. Chemical car­ cinogens such as polycyclic hydrocarbons, asbestos, and dioxin may be involved in the pathogenesis. Iatrogenic Factors  Sarcomas in bone or soft tissues occur in patients who are treated with radiation therapy. The tumor nearly always arises in the irradiated field. The risk increases with time. Viruses  Kaposi’s sarcoma (KS) in patients with HIV type 1, classic KS, and KS in HIV-negative homosexual men is caused by human herpesvirus (HHV) 8 (Chap. 200). No other sarcomas are associated with viruses. Immunologic Factors  Congenital or acquired immunodefi­ ciency, including therapeutic immunosuppression, increases the risk of sarcoma. ■ ■GENETIC CONSIDERATIONS Li-Fraumeni syndrome is a familial cancer syndrome in which affected individuals have germline abnormalities of the tumorsuppressor gene p53 and an increased incidence of soft tissue sarcomas and other malignancies, including breast cancer, osteosar­ coma, brain tumor, leukemia, and adrenal carcinoma (Chap. 76). Neurofibromatosis 1 (NF-1; peripheral form, von Recklinghausen’s disease) is characterized by multiple neurofibromas and café-au-lait spots. Neurofibromas occasionally undergo malignant degeneration to become malignant peripheral nerve sheath tumors. The gene for NF1 is located in the pericentromeric region of chromosome 17 and encodes neurofibromin, a tumor-suppressor protein with guanosine 5′-triphosphate (GTP)ase-activating activity that inhibits ras function (Chap. 95). Germline mutation of the RB1 locus (chromosome 13q14) in patients with inherited retinoblastoma is associated with the devel­ opment of osteosarcoma in those who survive the retinoblastoma and of soft tissue sarcomas unrelated to radiation therapy. Other soft tissue tumors, including desmoid tumors, lipomas, leiomyomas, neuroblasto­ mas, and paragangliomas, occasionally show a familial predisposition. CHAPTER 96 Soft Tissue and Bone Sarcomas and Bone Metastases Insulin-like growth factor (IGF) type II is produced by some sarco­ mas and may act as an autocrine growth factor and as a motility factor that promotes metastatic spread. IGF-II stimulates growth through IGF-I receptors, but its effects on motility are through different recep­ tors. If secreted in large amounts, IGF-II may produce hypoglycemia (Chaps. 98 and 418). A large international sarcoma kindred study including 1162 patients and 6545 Caucasian controls revealed that about half the patients with sarcoma have putatively pathogenic mono­ genic and polygenic variation in previously reported and new cancer genes, some of them representing therapeutically actionable targets. These patients were diagnosed with sarcoma at an earlier age compared to controls. ■ ■CLASSIFICATION Approximately 20 different groups of sarcomas are recognized on the basis of the pattern of differentiation toward normal tissue. For example, rhabdomyosarcoma shows evidence of skeletal muscle fibers with cross-striations; leiomyosarcomas contain interlacing fascicles of spindle cells resembling smooth muscle; and liposarcomas contain adipocytes. When precise characterization of the group is not possible, the tumors are called unclassified sarcomas. All of the primary bone sarcomas can also arise from soft tissues (e.g., extraskeletal osteosar­ coma). The entity malignant fibrous histiocytoma (MFH) includes many tumors previously classified as fibrosarcomas or as pleomorphic variants of other sarcomas and is characterized by a mixture of spindle (fibrous) cells and round (histiocytic) cells arranged in a storiform pattern with frequent giant cells and areas of pleomorphism. As immu­ nohistochemical suggestion of differentiation, particularly myogenic differentiation, may be found in a significant fraction of these patients, many are now characterized as poorly differentiated leiomyosarcomas, and the terms undifferentiated pleomorphic sarcoma (UPS) and myxofi­ brosarcoma are replacing MFH and myxoid MFH. For purposes of treatment, most soft tissue sarcomas can be consid­ ered together. However, some specific tumors have distinct features. For example, liposarcoma can have a spectrum of behaviors. Pleomor­ phic liposarcomas and dedifferentiated liposarcomas behave like other high-grade sarcomas; in contrast, well-differentiated liposarcomas (better termed atypical lipomatous tumors) lack metastatic potential, and myxoid liposarcomas metastasize infrequently, but, when they do, they have a predilection for unusual metastatic sites containing fat, such as the retroperitoneum, mediastinum, and subcutaneous tissue. Rhabdomyosarcomas, Ewing’s sarcoma, and other small-cell sarcomas tend to be more aggressive and are more responsive to chemotherapy than other soft tissue sarcomas. Approximately a third of all soft tissue sarcomas have a translocation that may have diagnostic and prognostic relevance; for example, 90% of synovial sarcomas contain a characteristic chromosomal translocation t(X;18)(p11;q11) involving a nuclear transcription factor on chromo­ some 18 called SYT and two breakpoints on X. Patients with transloca­ tions to the second X breakpoint (SSX2) may have longer survival than those with translocations involving SSX1. Targeting these transloca­ tions for therapy is an area of ongoing investigation. Gastrointestinal stromal tumors (GISTs), previously classified as gastrointestinal leiomyosarcomas, are now recognized as a distinct entity within soft tissue sarcomas. Its cell of origin resembles the interstitial cell of Cajal, which controls peristalsis. The majority of malignant GISTs have activating mutations of the c-kit gene that result in ligand-independent phosphorylation and activation of the KIT receptor tyrosine kinase, leading to tumorigenesis. Approximately 5–10% of tumors will have a mutation in the platelet-derived growth factor receptor α (PDGFRA). GISTs that are wild type for both KIT and PDGFRA mutations may show mutations in SDH B, C, or D and may be driven by the IGF-I pathway. PART 4 Oncology and Hematology ■ ■DIAGNOSIS The most common presentation is an asymptomatic mass. Mechanical symptoms referable to pressure, traction, or entrapment of nerves or muscles may be present. All new and persistent or growing masses should be biopsied, either by a small incision or by a cutting needle (core-needle biopsy) placed so that it can be encompassed in the subsequent excision without compromising a definitive resection. Lymph node metastases occur in 5%, except in synovial and epithelioid sarcomas, clear cell sarcoma (melanoma of the soft parts), angiosarcoma, and rhabdomyo­ sarcoma, where nodal spread may be seen in 17%. The pulmonary paren­ chyma is the most common site of metastases. Exceptions are GISTs, which metastasize to the liver; myxoid liposarcomas, which seek fatty tissue; and clear cell sarcomas, which may metastasize to bones. Central nervous system metastases are rare, except in alveolar soft part sarcoma. Radiographic Evaluation  Imaging of the primary tumor is best with plain radiographs and magnetic resonance imaging (MRI) for tumors of the extremities or head and neck and by computed tomog­ raphy (CT) for tumors of the chest, abdomen, or retroperitoneal cavity. A radiograph and CT scan of the chest are important for the detection of lung metastases. Other imaging studies may be indicated, depending on the symptoms, signs, or histology. ■ ■STAGING AND PROGNOSIS The histologic grade and size of the primary tumor are the most important prognostic factors. The current American Joint Committee on Cancer (AJCC) staging system is shown in Table 96-1. Prognosis is related to the stage. Cure is common in the absence of metastatic disease, but a small number of patients with metastases can also be cured. Historically, most patients with stage IV disease used to die within 12 months, but with availability of multiple lines of treatments, median survival in second-line and beyond ranges from 13 to 18 months, and some patients may live with stable or slowly progressive disease for many years. TREATMENT Soft Tissue Sarcomas AJCC stage I patients are adequately treated with surgery alone. Stage II patients are considered for adjuvant radiation therapy. Stage III patients may benefit from neoadjuvant or adjuvant che­ motherapy. Stage IV patients are managed primarily with systemic therapy, with or without other modalities. TABLE 96-1  American Joint Commission on Cancer Staging System for Sarcomas, Eighth Edition T1 Tumor ≤5 cm in greatest dimension T2 Tumor >5 cm and ≤10 cm in greatest dimension T3 Tumor >10 cm and ≤15 cm in greatest dimension T4 Tumor >15 cm in greatest dimension N0 No regional lymph node metastasis or unknown lymph node status N1 Regional lymph node metastasis M0 No distant metastasis M1 Distant metastasis Stage Groups Stage IA T1; N0; M0; G1 Stage IB T2, T3, T4; N0; M0; G1 Stage II T1; N0; M0; G2/3 Stage IIIA T1A, T2; N0; M0; G2/3 Stage IIIB T3, T4; N0; M0; G2/3 Stage IV Any T; N1; M0; any G Any T; any N; M1; any G SURGERY Soft tissue sarcomas tend to grow along fascial planes, with the surrounding soft tissues compressed to form a pseudocapsule that gives the sarcoma the appearance of a well-encapsulated lesion. This is invariably deceptive because “shelling out,” or marginal exci­ sion, of such lesions results in a 50–90% probability of local recur­ rence. Wide excision with a negative margin, incorporating the biopsy site, is the standard surgical procedure for local disease. The adjuvant use of radiation therapy and/or chemotherapy improves the local control rate and permits the use of limb-sparing surgery with a local control rate (85–90%) comparable to that achieved by radical excisions and amputations. Limb-sparing approaches are indicated except when negative margins are not obtainable, when the risks of radiation are prohibitive, or when neurovascular struc­ tures are involved so that resection will result in serious functional consequences to the limb. RADIATION THERAPY External-beam radiation therapy is an adjuvant to limb-sparing surgery for improved local control. Preoperative radiation therapy allows the use of smaller fields and smaller doses but results in a higher rate of wound complications. Postoperative radiation therapy must be given to larger fields, because the entire surgical bed must be encompassed, and in higher doses to compensate for hypoxia in the operated field. This results in a higher rate of late complications. Brachytherapy or interstitial therapy, in which the radiation source is inserted into the tumor bed, is comparable in efficacy (except in low-grade lesions), less time consuming, and less expensive. With the advent of stereotactic body radiotherapy (SBRT), the role of radiation therapy in oligometastatic disease in various vis­ ceral sites is evolving. ADJUVANT CHEMOTHERAPY Chemotherapy is the mainstay of treatment for Ewing’s sarcomas/ primitive neuroectodermal tumors (PNETs) and rhabdomyosar­ comas. Meta-analysis of 14 randomized trials in non-small-cell sarcomas revealed a significant improvement in local control and disease-free survival in favor of doxorubicin-based chemotherapy. Overall survival improvement was 4% for all sites and 7% for the extremity site. An updated meta-analysis including four additional trials with doxorubicin and ifosfamide combination reported a statistically significant 6% survival advantage in favor of chemo­ therapy. A chemotherapy regimen including an anthracycline and ifosfamide with growth factor support improved overall survival by 19% for high-risk (high-grade, ≥5 cm primary, or locally recurrent) extremity soft tissue sarcomas. Long-term follow-up of a trial evaluating neoadjuvant use of the same combination confirms survival advantage and reports a 10-year survival of 61%. A more contemporary randomized trial compared the standard anthra­ cycline and ifosfamide combination to specific histology-tailored chemotherapy as an active control and confirmed superiority of the standard regimen. ADVANCED DISEASE Metastatic soft tissue sarcomas are largely incurable, but up to 20% of patients who achieve a complete response become long-term sur­ vivors. The therapeutic intent, therefore, is to produce a complete remission with chemotherapy (<10%) and/or surgery (30–40%). Surgical resection of metastases, whenever possible, is an integral part of the management. Some patients benefit from repeated surgi­ cal excision of metastases. The two most active chemotherapeutic agents are doxorubicin and ifosfamide. These drugs show a steep dose-response relationship in sarcomas. Gemcitabine with or with­ out docetaxel has become an established second-line regimen and is particularly active in patients with UPS and leiomyosarcomas. Dacarbazine also has some modest activity. Taxanes have selective activity in angiosarcomas, and vincristine, etoposide, and irino­ tecan are effective in rhabdomyosarcomas and Ewing’s sarcomas. Pazopanib, an inhibitor of the vascular endothelial growth factor, platelet-derived growth factor (PDGF), and c-kit, is approved for patients with advanced soft tissue sarcomas excluding liposarcomas after failure of chemotherapy. Two additional chemotherapy drugs have gained approval from the U.S. Food and Drug Administration (FDA). Trabectedin was compared to dacarbazine in a large phase 3 randomized study in advanced leiomyosarcomas and liposarcomas after failure of an anthracycline and resulted in significant improve­ ment in progression-free survival. Eribulin was also tested in a similar trial and showed improvement in survival, predominantly in the liposarcoma subgroup, and is therefore now approved for that subset. Tazemetostat, an EZH2 inhibitor, is now approved for use in metastatic epithelioid sarcomas characterized by loss of tumorsuppressor gene INI1, resulting in activation of the EZH2 pathway. Nab-sirolimus, an inhibitor of the mammalian target of rapamycin (mTOR) pathway, is now approved for treatment of metastatic perivascular epithelioid cell tumors (PEComas). The FDA granted approval for nirogacestat, a γ-secretase inhibitor, for the treatment of desmoid tumors. Imatinib targets KIT and PDGF tyrosine kinase activity and is standard therapy for advanced/metastatic GISTs and dermatofibrosarcoma protuberans. Imatinib is also indicated as adjuvant therapy for completely resected primary GISTs. Three years of adjuvant imatinib appear to be superior to 1 year of therapy for high-risk GISTs, although the optimal treatment dura­ tion remains unknown. Sunitinib and regorafenib are approved for second- and third-line use, respectively, in metastatic GIST after failure of or intolerance to imatinib. Ripretinib, an inhibitor of c-kit and PDGFRA, was approved for fourth-line use in metastatic GIST based on a placebo-controlled randomized trial reporting an improved median progression-free and overall survival. Avapritinib also received approval for use in the specific molecular subset of PDGFRA D842V–mutant metastatic GIST. Immune checkpoint inhibitors have generally been ineffective in most forms of sarcoma, but atezolizumab, an anti-PD-L1 antibody, has produced responses in about one-third of patients with alveolar soft part sarcoma. BONE SARCOMAS ■ ■INCIDENCE AND EPIDEMIOLOGY Bone sarcomas are rarer than soft tissue sarcomas; they accounted for only 0.2% of all new malignancies and 3970 new cases in the United States in 2023. Several benign bone lesions have the potential for malignant transformation. Enchondromas and osteochondromas can transform into chondrosarcoma; fibrous dysplasia, bone infarcts, and Paget’s disease of bone can transform into either UPS or osteosarcoma. ■ ■CLASSIFICATION Benign Tumors  The common benign bone tumors include enchondroma, osteochondroma, chondroblastoma, and chondromyx­ oid fibroma, of cartilage origin; osteoid osteoma and osteoblastoma, of bone origin; fibroma and desmoplastic fibroma, of fibrous tissue ori­ gin; hemangioma, of vascular origin; and giant cell tumor, of unknown origin. Malignant Tumors  The most common malignant tumors of bone are plasma cell tumors (Chap. 116). The four most common malignant nonhematopoietic bone tumors are osteosarcoma, chondrosarcoma, Ewing’s sarcoma, and UPS. Rare malignant tumors include chordoma (of notochordal origin), malignant giant cell tumor, adamantinoma (of unknown origin), and hemangioendothelioma (of vascular origin). Musculoskeletal Tumor Society Staging System  Sarcomas of bone are staged according to the Musculoskeletal Tumor Society stag­ ing system based on grade and compartmental localization. A Roman numeral reflects the tumor grade: stage I is low grade, stage II is high grade, and stage III includes tumors of any grade that have lymph node or distant metastases. In addition, the tumor is given a letter reflecting its compartmental localization. Tumors designated A are intracom­ partmental (i.e., confined to the same soft tissue compartment as the initial tumor), and tumors designated B are extracompartmental (i.e., extending into the adjacent soft tissue compartment or into bone). The tumor-node-metastasis (TNM) staging system is shown in Table 96-2. CHAPTER 96 ■ ■OSTEOSARCOMA Osteosarcoma, accounting for almost 45% of all bone sarcomas, is a spindle cell neoplasm that produces osteoid (unmineralized bone) or bone. Approximately 60% of all osteosarcomas occur in children and Soft Tissue and Bone Sarcomas and Bone Metastases TABLE 96-2  Staging System for Bone Sarcomas Primary tumor (T) TX Primary tumor cannot be assessed T0 No evidence of primary tumor T1 Tumor ≤8 cm in greatest dimension T2 Tumor >8 cm in greatest dimension T3 Discontinuous tumors in the primary bone site Regional lymph nodes (N) NX Regional lymph nodes cannot be assessed N0 No regional lymph node metastasis N1 Regional lymph node metastasis Distant metastasis (M) MX Distant metastasis cannot be assessed M0 No distant metastasis M1 Distant metastasis M1a Lung M1b Other distant sites Histologic grade (G) GX Grade cannot be assessed G1 Well differentiated—low grade G2 Moderately differentiated—low grade G3 Poorly differentiated—high grade G4 Undifferentiated—high grade (Ewing’s is always classed G4) Stage Grouping Stage IA T1 N0 M0 G1,2 low grade Stage IB T2 N0 M0 G1,2 low grade Stage IIA T1 N0 M0 G3,4 high grade Stage IIB T2 N0 M0 G3,4 high grade Stage III T3 N0 M0 Any G Stage IVA Any T N0 M1a Any G Stage IVB Any T N1 Any M Any G Any T Any N M1b Any G adolescents in the second decade of life, and ∼10% occur in the third decade of life. Osteosarcomas in the fifth and sixth decades of life are frequently secondary to either radiation therapy or transformation in a preexisting benign condition, such as Paget’s disease. Males are affected 1.5–2 times as often as females. Osteosarcoma has a predilection for metaphyses of long bones; the most common sites of involvement are the distal femur, proximal tibia, and proximal humerus. The classifica­ tion of osteosarcoma is complex, but 75% of osteosarcomas fall into the “classic” category, which includes osteoblastic, chondroblastic, and fibroblastic osteosarcomas. The remaining 25% are classified as “variants” on the basis of (1) clinical characteristics, as in the case of osteosarcoma of the jaw, postradiation osteosarcoma, or Paget’s osteo­ sarcoma; (2) morphologic characteristics, as in the case of telangiectatic osteosarcoma, small-cell osteosarcoma, or epithelioid osteosarcoma; or (3) location, as in parosteal or periosteal osteosarcoma. Diagnosis usu­ ally requires a synthesis of clinical, radiologic, and pathologic features. Patients typically present with pain and swelling of the affected area. A plain radiograph reveals a destructive lesion with a moth-eaten appear­ ance, a spiculated periosteal reaction (sunburst appearance), and a cuff of periosteal new bone formation at the margin of the soft tissue mass (Codman’s triangle). A CT scan of the primary tumor is best for defin­ ing bone destruction and the pattern of calcification, whereas MRI is better for defining intramedullary and soft tissue extension. A chest radiograph and CT scan are used to detect lung metastases. Metastases to the bony skeleton should be imaged by a bone scan or by fluoro­ deoxyglucose positron emission tomography (FDG-PET). Almost all osteosarcomas are hypervascular and PET-avid. Pathologic diagnosis is established either with a core-needle biopsy, where feasible, or with an open biopsy with an appropriately placed incision that does not com­ promise future limb-sparing resection. Most osteosarcomas are high grade. The most important predictive factor for long-term survival is response to chemotherapy. Preoperative chemotherapy followed by limb-sparing surgery (which can be accomplished in >80% of patients) followed by postoperative chemotherapy is standard management. The effective drugs are doxorubicin, ifosfamide, cisplatin, and high-dose methotrexate with leucovorin rescue. The various combinations of these agents that have been used have all been about equally success­ ful. Long-term survival rates in extremity osteosarcoma range from 60 to 80%. Osteosarcoma is radioresistant; radiation therapy has no role in the routine management. UPS is considered a part of the spectrum of osteosarcoma and is managed similarly. A randomized trial has shown improved progression-free survival with regorafenib compared to placebo. PART 4 Oncology and Hematology ■ ■CHONDROSARCOMA Chondrosarcoma, which constitutes ~20–25% of all bone sarcomas, is a tumor of adulthood and old age, with a peak incidence in the fourth to sixth decades of life. It has a predilection for the flat bones, especially the shoulder and pelvic girdles, but can also affect the diaphyseal por­ tions of long bones. Chondrosarcomas can arise de novo or as a malig­ nant transformation of an enchondroma or, rarely, of the cartilaginous cap of an osteochondroma. Chondrosarcomas have an indolent natural history and typically present as pain and swelling. Radiographically, the lesion may have a lobular appearance with mottled or punctate or annular calcification of the cartilaginous matrix. It is difficult to distinguish low-grade chondrosarcoma from benign lesions by x-ray or histologic examination. The diagnosis is therefore influenced by clinical history and physical examination. A new onset of pain, signs of inflammation, and progressive increase in the size of the mass sug­ gest malignancy. The histologic classification is complex, but most tumors fall within the classic category. Like other bone sarcomas, highgrade chondrosarcomas spread to the lungs. Most chondrosarcomas are resistant to chemotherapy, and surgical resection of primary or recurrent tumors, including pulmonary metastases, is the mainstay of therapy with the exception of two histologic variants. Dedifferentiated chondrosarcoma has a high-grade osteosarcoma or a UPS component that responds to chemotherapy. Mesenchymal chondrosarcoma, a rare variant composed of a small-cell element, also is responsive to systemic chemotherapy and is treated like Ewing’s sarcoma. ■ ■EWING’S SARCOMA Ewing’s sarcoma, which constitutes ~10–15% of all bone sarcomas, is common in adolescence and has a peak incidence in the second decade of life. It typically involves the diaphyseal region of long bones and also has an affinity for flat bones. The plain radiograph may show a charac­ teristic “onion peel” periosteal reaction with a generous soft tissue mass, which is better demonstrated by CT or MRI. This mass is composed of sheets of monotonous, small, round, blue cells and can be confused with lymphoma, embryonal rhabdomyosarcoma, and small-cell carcinoma. The presence of p30/32, the product of the mic-2 gene (which maps to the pseudoautosomal region of the X and Y chromosomes), is a cell-sur­ face marker for Ewing’s sarcoma (and other members of the Ewing fam­ ily of tumors, previously also called PNETs). Most PNETs arise in soft tissues; they include peripheral neuroepithelioma, Askin’s tumor (chest wall), and esthesioneuroblastoma. The classic cytogenetic abnormality associated with this disease is a reciprocal translocation of the long arms of chromosomes 11 and 22, t(11;22), which creates a chimeric gene product of unknown function with components from the fli-1 gene on chromosome 11 and ews on chromosome 22. This disease is very aggres­ sive, and it is therefore considered a systemic disease. Common sites of metastases are lung, bones, and bone marrow. Systemic chemotherapy is the mainstay of therapy, often being used before surgery. Doxoru­ bicin, cyclophosphamide or ifosfamide, etoposide, and vincristine are active drugs. Topotecan or irinotecan in combination with an alkylating agent is often used in relapsed patients. Local treatment for the primary tumor includes surgical resection, usually with limb salvage or radiation therapy. Overall cure rates approach 60–70% for localized tumors. TUMORS METASTATIC TO BONE Bone is a common site of metastasis for carcinomas of the prostate, breast, lung, kidney, bladder, and thyroid and for lymphomas and sarcomas. Prostate, breast, and lung primaries account for 80% of all bone metastases. Metastatic tumors of bone are more common than primary bone tumors. Tumors usually spread to bone hematogenously, but local invasion from soft tissue masses also occurs. In descending order of frequency, the sites most often involved are the vertebrae, proximal femur, pelvis, ribs, sternum, proximal humerus, and skull. Bone metastases may be asymptomatic or may produce pain, swelling, nerve root or spinal cord compression, pathologic fracture, or myelo­ phthisis (replacement of the marrow). Symptoms of hypercalcemia may be noted in cases of bony destruction. Pain is the most frequent symptom. It usually develops gradually over weeks, is usually localized, and often is more severe at night. When patients with back pain develop neurologic signs or symptoms, emergency evaluation for spinal cord compression is indicated (Chap. 80). Bone metastases exert a major adverse effect on quality of life in cancer patients. Cancer in the bone may produce osteolysis, osteogenesis, or both. Osteolytic lesions result when the tumor produces substances that can directly elicit bone resorption (vitamin D–like steroids, prostaglan­ dins, or parathyroid hormone–related peptide) or cytokines that can induce the formation of osteoclasts (interleukin 1 and tumor necrosis factor). Osteoblastic lesions result when the tumor produces cytokines that activate osteoblasts. In general, purely osteolytic lesions are best detected by plain radiography, but they may not be apparent until they are >1 cm. These lesions are more commonly associated with hyper­ calcemia and with the excretion of hydroxyproline-containing peptides indicative of matrix destruction. When osteoblastic activity is promi­ nent, the lesions may be readily detected using radionuclide bone scan­ ning (which is sensitive to new bone formation), and the radiographic appearance may show increased bone density or sclerosis. Osteoblastic lesions are associated with higher serum levels of alkaline phosphatase and, if extensive, may produce hypocalcemia. Although some tumors may produce mainly osteolytic lesions (e.g., kidney cancer) and oth­ ers mainly osteoblastic lesions (e.g., prostate cancer), most metastatic lesions produce both types of lesion and may go through stages where one or the other predominates. In older patients, particularly women, it may be necessary to distinguish metastatic disease of the spine from osteoporosis. In # 26 - 97 Carcinoma of Unknown Primary ### 97 Carcinoma of Unknown Primary osteoporosis, the cortical bone may be preserved, whereas cortical bone destruction is usually noted with metastatic cancer. TREATMENT Metastatic Bone Disease Treatment of metastatic bone disease depends on the underlying malignancy and the symptoms. Some metastatic bone tumors are curable (lymphoma, Hodgkin’s lymphoma), and others are treated with palliative intent. Pain may be relieved by local radiation therapy. Hormonally responsive tumors are responsive to hormone inhibition (antiandrogens for prostate cancer, antiestrogens for breast cancer). Strontium-89, samarium-153, and radium-223 are bone-seeking radionuclides that can exert antitumor effects and relieve symptoms. Denosumab, a monoclonal antibody that binds to RANK ligand, inhibits osteoclastic activity and increases bone mineral density. Bisphosphonates such as pamidronate may relieve pain and inhibit bone resorption, thereby maintaining bone min­ eral density and reducing risk of fractures in patients with osteo­ lytic metastases from breast cancer and multiple myeloma. Careful monitoring of serum electrolytes and creatinine is recommended. Monthly administration prevents bone-related clinical events and may reduce the incidence of bone metastases in women with breast cancer. When the integrity of a weight-bearing bone is threatened by an expanding metastatic lesion that is refractory to radiation therapy, prophylactic internal fixation is indicated. Overall survival is related to the prognosis of the underlying tumor. Bone pain at the end of life is particularly common; an adequate pain relief regimen including sufficient amounts of narcotic analgesics is required. The management of hypercalcemia is discussed in Chap. 422. ■ ■FURTHER READING Alvarez RA et al: Optimization of the therapeutic approach to patients with sarcoma: Delphi consensus. Sarcoma 2019:4351308, 2019. Ballinger ML et al: Monogenic and polygenic determinants of sarcoma risk: An international genetic study. Lancet Oncol 17:1261, 2016. Beird HC et al: Osteosarcoma. Nat Rev Dis Primers 8:77, 2022. Gounder M et al: Nirogacestat, a γ-secretase inhibitor for desmoid tumors. N Engl J Med 388:898, 2023. Meyer M, Seetharam M: First-line therapy for metastatic soft tissue sarcoma. Curr Treat Options Oncol 20:6, 2019. Pasquali S, Gronchi A: Neoadjuvant chemotherapy in soft tissue sarcomas: Latest evidence and clinical implications. Ther Adv Med Oncol 9:415, 2017. Patel S, Reichardt P: An updated review of the treatment landscape for advanced gastrointestinal stromal tumors. Cancer 127:2185, 2021. Ratan R, Patel SR: Chemotherapy for soft tissue sarcoma. Cancer 122:2952, 2016. Wagner MJ et al: Chemotherapy for bone sarcoma in adults. J Oncol Pract 12:208, 2016. Kanwal Raghav, James L. Abbruzzese Carcinoma of Unknown Primary Carcinoma (or cancer) of unknown primary (CUP) is a biopsy-proven malignancy for which the anatomic site of origin remains unidenti­ fied after a standardized detailed diagnostic evaluation. CUP is one of the 10 most frequently diagnosed cancers globally, accounting for 3–5% of all malignancies. Most investigators limit CUP to epithelial or undifferentiated cancers and do not include lymphomas, metastatic melanomas, and metastatic sarcomas because these cancers have spe­ cific histology and stage-based management guidelines, even in the absence of a primary site. CUP can occur in patients of all age groups including adolescents and young adults. The emergence of sophisticated imaging, robust immunohisto­ chemistry (IHC), and genomic and proteomic tools has challenged the “unknown” designation. Additionally, effective targeted therapies in several cancers and tissue-agnostic biomarker-driven therapies have endorsed a change in paradigm from empiricism to a personal­ ized approach to CUP management. The reasons cancers present as CUP remain unclear. One hypothesis is that the primary tumor either regresses after seeding the metastasis or remains so small that it is not detected. It is possible that CUP falls on the continuum of cancer presentation where the primary has been contained or eliminated by the natural body defenses, including the immune system. Alterna­ tively, CUP may represent a specific malignant event that results in an increase in metastatic spread or survival relative to the primary. Whether the CUP metastases truly define a clone that is genetically and phenotypically unique to this diagnosis remains to be determined. Since liver is a common site of CUP presentation, intrahepatic chol­ angiocarcinoma (ICC) can be often misdiagnosed as CUP. Of note, the incidence of ICC is increasing, whereas at the same time, that of CUP is declining. Improvements in diagnostic technologies including nextgeneration sequencing and other molecular techniques and awareness among clinicians to differentiate the two are possibly contributing to an increased recognition and incidence of ICC. CHAPTER 97 Carcinoma of Unknown Primary CUP BIOLOGY Studies looking for unique signature abnormalities in CUP tumors have not been positive. Abnormalities in chromosomes 1 and 12 and other complex cytogenetic abnormalities have been reported. Aneu­ ploidy has been described in 70% of CUP patients with metastatic adenocarcinoma or undifferentiated carcinoma. The overexpression of various genes, including RAS, BCL2 (40%), HER2 (11%), and P53 (26–53%), has been identified in CUP samples, but they are found in many other malignancies. The extent of angiogenesis in CUP relative to that in metastases from known primaries has also been evaluated, but no consistent findings have emerged. Although current comprehen­ sive genomic profiling efforts may help identify targeted therapeutic approaches to improve outcomes for this disease as discussed below, they have failed thus far to reveal a distinct molecular signature. More comprehensive and integrated multiomic efforts are needed to provide insights into CUP biology through recognition of molecular aberra­ tions that specifically drive metastatic growth. APPROACH TO THE PATIENT Carcinoma (or Cancer) of Unknown Primary Initial CUP evaluation has two goals: search for the primary or “putative primary” tumor based on clinicopathologic evaluation of the metastases and determine the extent of disease. Focused evaluation directed by clinicopathologic cues allows for judicious and efficient use of diagnostic tests. Obtaining a thorough medical history from CUP patients is essential, including paying particular attention to risk factors, prior surgeries, and family medical history to assess potential hereditary cancers. Adequate physical examina­ tion, including a digital rectal examination in men and breast and pelvic examinations in women, should be performed based on clini­ cal presentation. Finally, all patients with CUP, in the absence of contraindication, must undergo a computed tomography (CT) scan of chest, abdomen, and pelvis as a part of their standard workup. ■ ■ROLE OF SERUM TUMOR MARKERS AND CYTOGENETICS Most tumor markers, including carcinoembryonic antigen (CEA), CA-125, CA 19-9, and CA 15-3, are nonspecific and not helpful in determining the primary site. Men who present with adenocarcinoma and predominant osteoblastic metastasis should undergo a prostatespecific antigen (PSA) test. In patients with undifferentiated or poorly differentiated carcinoma (especially with a midline tumor), elevated β-human chorionic gonadotropin (β-hCG) and α fetoprotein (AFP) levels suggest the possibility of an extragonadal germ cell (testicular) tumor. With the availability of advanced IHC, cytogenetic studies are rarely needed. ■ ■ROLE OF IMAGING STUDIES In the absence of contraindications, a baseline intravenous (IV) con­ trast CT scan of the chest, abdomen, and pelvis is the standard of care. This helps to search for the primary tumor, evaluate the extent of disease, and select the most accessible biopsy site. With precise imag­ ing and reporting, latent primary cancers, defined as appearance of a new primary cancer after a latent period of several months to years, is uncommon and seen in ≤5% of CUP patients, usually in patients with very indolent presentations and/or highly responsive metastatic cancers that allows a latent primary to emerge (grow) over time. Mammography should be performed in women who present with metastatic adenocarcinoma, especially in those with isolated axillary lymphadenopathy. Magnetic resonance imaging (MRI) of the breast can be considered in patients with axillary adenopathy and suspected occult primary breast carcinoma following a negative mammography and ultrasound. The results of these imaging modalities can influence surgical management; a negative MRI of the breast predicts a low tumor yield at mastectomy. PART 4 Oncology and Hematology A conventional workup for a squamous cell carcinoma and cervical CUP (neck lymphadenopathy with no known primary tumor) includes a CT scan or MRI and invasive studies, including indirect and direct laryngoscopy, bronchoscopy, and upper endoscopy. Ipsilateral (or bilat­ eral) staging tonsillectomy has been recommended for these patients. 18-Fluorodeoxyglucose positron emission tomography (18-FDG-PET) scans are useful in this patient population and may help guide the biopsy; determine the extent of disease; facilitate the appropriate treat­ ment, including planning radiation fields; and help with disease sur­ veillance. Several studies have evaluated the utility of PET in patients with squamous cervical CUP, and head and neck primary tumors were identified in ~21–30%. The diagnostic contribution of PET to the evaluation of other CUP presentations (outside of the neck adenopathy indication) remains controversial and is not routinely recommended. PET-CT can be help­ ful for patients with bone metastases and those deemed candidates for aggressive multimodality therapy (surgical intervention/radiation) such as patients with solitary metastatic disease because the identifica­ tion of disease in addition to the solitary metastatic site may affect treatment planning. Invasive studies, including upper endoscopy, colonoscopy, and bronchoscopy, should be limited to symptomatic patients or those with laboratory, imaging, or pathologic abnormalities that suggest that these techniques will result in a high yield in finding a primary cancer. CK7 CK20 CK7+ CK20+ CK7+ CK20– CK7– CK20+ CK7– CK20– Lung adenocarcinoma Breast carcinoma Thyroid carcinoma Endometrial carcinoma Cervical carcinoma Salivary gland carcinoma Cholangiocarcinoma Pancreatic carcinoma Urothelial tumors Ovarian mucinous adenocarcinoma Pancreatic adenocarcinoma Cholangiocarcinoma FIGURE 97-1  Approach to cytokeratin (CK7 and CK20) markers used in adenocarcinoma of unknown primary. TABLE 97-1  Major Histologies in Carcinoma (Cancer) of Unknown Primary HISTOLOGY PROPORTION, % Well to moderately differentiated adenocarcinoma Squamous cell cancer Poorly differentiated adenocarcinoma, poorly differentiated carcinoma Neuroendocrine Undifferentiated malignancy ■ ■ROLE OF PATHOLOGIC STUDIES A detailed pathologic examination of the most accessible biopsied tissue specimen is mandatory in CUP patients. Pathologic evaluation typically consists of hematoxylin and eosin stains and IHC tests. The importance of adequate tissue acquisition cannot be overemphasized in CUP. In addition to pathologic evaluation, tissue is also needed for molecular profiling, which can aid in identifying biomarkers suggest­ ing the primary site for effective therapeutics including targeted agents, immunotherapy, and clinical trials. Light Microscopy Evaluation  Adequate tissue obtained prefer­ ably by excisional biopsy or core needle biopsy (instead of only a fineneedle aspiration) is stained with hematoxylin and eosin and subjected to light microscopic examination. On light microscopy, 60–65% of CUP is adenocarcinoma, and 5% is squamous cell carcinoma. The remaining 30–35% is poorly differentiated adenocarcinoma, poorly differentiated carcinoma, or poorly differentiated neoplasm. A small percentage of lesions are diagnosed as neuroendocrine cancers (2%), mixed tumors (adenosquamous or sarcomatoid carcinomas), or undif­ ferentiated neoplasms (Table 97-1). Role of IHC Analysis  IHC stains are peroxidase-labeled antibod­ ies against specific tumor antigens that are used to define tumor lin­ eage. The number of available IHC stains is ever-increasing. However, a tiered and uniform approach to tissue evaluation in the CUP setting is lacking. For CUP cases, more is not necessarily better, and IHC stains should be used in conjunction with the patient’s clinical presen­ tation and imaging studies to select the best therapy. Communication between the clinician and pathologist is essential. No stain is 100% sensitive or specific, and under-/overinterpretation should be avoided. Poor differentiation, even in known primary tumors, decreases sensi­ tivity of hallmark IHC markers. PSA and thyroglobulin tissue markers, which are positive in prostate and thyroid cancer, respectively, are two of the most specific markers. However, these cancers rarely present as CUP, so the yield of these tests may be low. Figure 97-1 delineates a simple algorithm for immunohistochemical staining in CUP cases. Table 97-2 lists additional tests that may be useful to further define the tumor lineage. A more comprehensive algorithm may improve the diagnostic accuracy but can make the process complex and increase Colorectal carcinoma Merkel cell carcinoma Hepatocellular carcinoma Renal cell carcinoma Prostate carcinoma Squamous cell and small- cell lung carcinoma Head and neck carcinoma TABLE 97-2  Select Immunohistochemical Stains Useful in the Diagnosis of CUP COMMONLY CONSIDERED IHC TO ASSIST IN DIFFERENTIAL DIAGNOSIS OF CUPa LIKELY PRIMARY PROFILE Breast ER, GCDFP-15, mammaglobin, HER2/neu, GATA3 Ovarian/müllerian ER, WT1, CK7, PAX8, PAX2 Lung adenocarcinoma TTF-1; nuclear staining, napsin A, SP-A1 Germ cell β-hCG, AFP, OCT3/4, CKIT, CD30 (embryonal), SALL4 Prostate PSA, α-methylacyl CoA racemase/P504S (AMACR/ P504S), P501S (prostein), PSMA, NKX3-1 Intestinal CK7, CK20, CDX-2, CEA Neuroendocrine Chromogranin, synaptophysin, CD56 Sarcoma Desmin (desmoid tumors), factor VIII (angiosarcomas), CD31, smooth muscle actin (leiomyosarcoma), MyoD1 (rhabdomyosarcoma) Renal RCC, CD10, PAX8, CD10 Hepatocellular carcinoma Hep Par-1, Arg-1, glypican-3 Melanoma S100, SOX-10, vimentin, HMB-45, tyrosinase, melan-A Urothelial CK7, CK20, thrombomodulin, uroplakin III Mesothelioma Calretinin, WT1, D2-40, mesothelin Lymphoma LCA, CD3, CD4, CD5, CD20, CD45 SCC p63, p40 (lung SCC), CK5/6 aPatterns emerging from coexpression of stains are better than individual stains to suggest putative primary site. Even with optimization, no IHC panel is 100% sensitive or specific (e.g., ovarian mucinous carcinoma can exhibit positivity with intestinal markers). Abbreviations: AFP, α fetoprotein; Arg-1, arginase-1; β-hCG, β-human chorionic gonadotropin; CEA, carcinoembryonic antigen; CUP, carcinoma of unknown primary; ER, estrogen receptor; GCDFP-15, gross cystic disease fibrous protein-15; IHC, immunohistochemistry; LCA, leukocyte common antigen; PSA, prostatespecific antigen; PSMA, prostate-specific membrane antigen; SCC, squamous cell carcinoma; SP-A1, surfactant protein A precursor; TTF, thyroid transcription factor; WT, Wilms’ tumor. cost. With the use of IHC markers, electron microscopic analysis, which is time-consuming and expensive, is rarely performed today. There are >20 subtypes of cytokeratin (CK) intermediate filaments with different molecular weights and differential expression in various cell types and cancers. Monoclonal antibodies to specific CK subtypes have been used to help classify tumors according to their site of origin; commonly used CK stains in adenocarcinoma CUP are CK7 and CK20. CK7 is found in tumors of the lung, ovary, endometrium, breast, and upper gastrointestinal tract including pancreaticobiliary cancers, whereas CK20 is normally expressed in the gastrointestinal epithelium, urothelium, and Merkel cells. The nuclear CDX-2 transcription fac­ tor, which is the product of a homeobox gene necessary for intestinal organogenesis, is often used to aid in the diagnosis of gastrointestinal adenocarcinomas. However, CDX-2 positivity can be seen with enteric or mucinous differentiation in tumors from diverse primary sites (e.g., mucinous ovarian cancers). Thyroid transcription factor 1 (TTF-1) nuclear staining is frequently positive in lung and thyroid cancers. Approximately 68% of adeno­ carcinomas and 25% of squamous cell lung cancers stain positive for TTF-1, which helps differentiate a lung primary tumor from metastatic adenocarcinoma in a pleural effusion, the mediastinum, or the lung parenchyma. Gross cystic disease fibrous protein-15 (GCDFP-15), a 15-kDa monomer protein, is a marker of apocrine differentiation that is detected in 62–72% of breast carcinomas. GATA3 is being increasingly used in the CUP setting when there is concern for a breast primary and can be particularly useful as a marker for metastatic breast carcinoma, especially triple-negative and metaplastic carcinomas, which lack spe­ cific endocrine markers of mammary origin. UROIII, high-molecularweight cytokeratin, thrombomodulin, and CK20 are the markers used to diagnose lesions of urothelial origin. IHC performs the best when used in groups that give rise to patterns that are strongly indicative of certain profiles. For example, the TTF-1/ CK7+ and CK20+/CDX-2+/CK7− phenotypes have been reported as very suggestive of lung and lower gastrointestinal cancer profiles, respectively. Despite their practical utility, these patterns have not been validated prospectively in CUP patients. IHC is not without its limitations; several factors affect tissue antigenicity (antigen retrieval, specimen processing, and fixation), interpretation of stains in tumor (nuclear, cytoplasmic, membrane) versus normal tissue, inter- and intraobserver variability, variable performance of different antibodies said to recognize the same antigen, and tissue heterogeneity and inad­ equacy (given small biopsy sizes). Communication with the patholo­ gist is critical to determine if acquisition of additional tissue will be beneficial in the pathologic evaluation. Pathologic features should not always supersede clinical or radiologic findings when considering testing for biomarkers of therapeutic response (e.g., epidermal growth factor receptor [EGFR], ALK mutations, human epidermal growth fac­ tor receptor 2 [HER2]). Role of Cancer Classifier Molecular Profiling  In the absence of a known primary, developing therapeutic strategies for CUP is chal­ lenging. The current diagnostic yield with imaging and immunochem­ istry is ~20–30% for CUP patients. To reduce diagnostic uncertainty, sophisticated molecular analytics have been applied to CUP samples. These include gene expression profiling, messenger RNA (mRNA), microRNA, and genetic and epigenetic profiling to classify CUP. CHAPTER 97 Gene expression profiles are most commonly generated using quan­ titative reverse transcriptase polymerase chain reaction (RT-PCR) or DNA microarray. Neural network programs are then used to develop predictive algorithms from the gene expression profiles. Typically, a training set of gene profiles from known cancers (preferably from metastatic sites) is used to train the software. Comprehensive gene expression databases that have become available for common malig­ nancies are then applied to CUP samples, and the program can then be used to predict the putative origin of a CUP sample. Carcinoma of Unknown Primary mRNA- or microRNA-based tissue of origin cancer classifier assays have also been studied in prospective and retrospective CUP trials. Other assays such as DNA methylation profiling predicted a primary cancer in 87% of 216 CUP patients. Incorporation of machine learning and nextgeneration sequencing has furthered prediction of these classifiers. Despite the sophistication of the cancer classifier molecular assays, most of the CUP studies have evaluated assay performance, although the challenge with validating the accuracy of an assay for CUP is that, by definition, the primary cancer diagnosis cannot be verified. Thus, current estimates of tissue of origin test accuracy have relied on indirect metrics, including comparison with pathology/IHC, clini­ cal presentation, appearance of latent primaries, and autopsies. Using these measures, the assays suggest a plausible primary in ~70–80% of patients studied. Three outcomes-based studies have been performed. First, a single-arm study reported a median survival of 12.5 months for patients who received assay-directed site-specific therapy. Second, a phase 2 trial of site-specific therapy, including molecularly targeted therapy, based on predicted tumor site from an algorithm using gene expression and alteration profile showed a 1-year survival of 53.1%. However, two randomized clinical trials evaluating site-specific therapy directed by gene expression profiling versus empirical chemotherapy with either paclitaxel plus carboplatin or gemcitabine plus cisplatin failed to show a significant improvement in survival with this approach. Firm conclusions of therapeutic impact cannot be drawn from these studies given the sample size, design, statistical biases, confounding variables including use of subsequent lines of (empiric) therapy, and heterogeneity of the CUP cancers. Additional studies are needed to bet­ ter understand the clinical impact of tissue of origin profiling tools and how these assays complement IHC and help guide therapy. Role of Next-Generation Sequencing  A significant push is being made toward personalized medicine across all cancer types with the goal of identifying driver mutation(s) in a patient who can be treated with targeted agents independent of the site of origin. A retrospective study of 200 CUP tumor specimens reported on genomic alterations using the hybrid capture–based FoundationOne assay. The authors reported that a large number of CUP samples (85%) harbored at least one clinically relevant genomic alteration with the potential to influence and personalize therapy. The mean number of genomic alter­ ations was 4.2 per tumor, and the most common genetic alterations included TP53 (55%), KRAS (20%), CDKN2A (19%), and ARID1A (11%). The adenocarcinoma CUP tumors were more frequently driven by genetic alterations in the receptor tyrosine kinase (RTK)/Ras/mitogenactivated protein kinase (MAPK) signaling pathway than nonadeno­ carcinoma CUP tumors. Although druggable genetic lesions seen in CUP are comparable to those in known primary cancer databases, whether molecularly stratified approaches for CUP will successfully improve outcomes remains to be seen and clinical trials are needed. In a single-arm phase 2 study of 97 patients with molecularly targeted therapy, five patients were found to have targetable EGFR mutations. Of these, four patients were treated with afatinib, an anti-EGFR drug, and two patients achieved a progression-free survival of >6 months. It is anticipated that second- and third-generation drugs targeting EGFR mutations are likely to be even more effective. The emerging use of assays looking for circulating tumor DNA (ctDNA), so-called liquid biopsies, has been increasingly useful within known tumor types and has stirred interest in their potential utility in CUP (Chap. 503). Ongoing histology and cellular-context agnostic prospective clinical trials are studying the presence of actionable mutations and matching patients to the right targeted drug. As this strategy gains traction, CUP would be a natural fit for genomic alteration–based targeted therapy independent of tumor site. Established tumor-agnostic therapies such as immune checkpoint inhibitors (pembrolizumab) for microsatellite instability high (MSI-H) or deficient mismatch repair (dMMR) tumors or tumors with high tumor mutation burden (TMB) and NTRK inhibi­ tors for NTRK fusion–positive tumors can help a small minority of CUP patients. PART 4 Oncology and Hematology TREATMENT Carcinoma (or Cancer) of Unknown Primary GENERAL CONSIDERATIONS The treatment of CUP continues to evolve, albeit slowly. The median survival of most patients with disseminated CUP is ~6–10 months. Adenocarcinoma Poorly differentiated adenocarcinoma CUP IHC to suggest “favored” primary Isolated axillary nodes in women Bone-only metastases in men (blastic) Solitary site of metastasis Peritoneal carcinoma Disseminated cancer, 2 or more sites involved Check PSA (in tumor and serum). If elevated, Rx as prostate cancer. If resectable, resect with or without prior C or CRT. If unresectable, C, RT, or CRT depending on location of tumor Breast MRI if mammogram and ultrasound are negative If PSA not elevated, C or RT as indicated MRI (+). Breast surgery or radiation. C and/or hormonal therapy for breast cancer. MRI (–). No surgery, consider radiation. C for breast cancer. FIGURE 97-2  Treatment algorithm for adenocarcinoma and poorly differentiated adenocarcinoma of unknown primary (CUP). C, chemotherapy; CRT, chemoradiation; GI, gastrointestinal; IHC, immunohistochemistry; MRI, magnetic resonance imaging; PSA, prostate-specific antigen; RT, radiation. Squamous cell CUP Disseminated, visceral metastases Metastatic inguinal adenopathy Metastatic cervical adenopathy Directed invasive tests as needed Perineal exam, anoscopy if needed. Pelvic examination in women. PET is optional. Triple endoscopy, consider tonsillectomy. CT neck and chest. PET is optional. If no extra-cervical disease—neck dissection followed by adjuvant RT vs RT alone. C for bulky disease. If localized, lymph node dissection, followed by local RT in select patients C in good performance status patients. RT as indicated. FIGURE 97-3  Treatment algorithm for squamous cell carcinoma of unknown primary (CUP). C, chemotherapy; CT, computed tomography; PET, positron emission tomography; RT, radiation. Systemic chemotherapy is the primary treatment modality in most patients with disseminated disease, but the careful integration of surgery, radiation therapy, and even periods of observation is important in the overall management of this condition (Figs. 97-2 and 97-3). Prognostic factors include performance status, site and number of metastases, response to chemotherapy, and serum lactate dehydrogenase (LDH) levels. Culine and colleagues developed a prognostic model using performance status and serum LDH levels, which allowed the assignment of patients into two subgroups with divergent outcomes. Raghav and colleagues developed a prognostic nomogram to provide individualized survival estimates for patients with CUP based on baseline gender, Eastern Cooperative Oncology If not suggestive of primary peritoneal, GI workup for primary. C, if good performance status. If suggestive of primary peritoneal cancer, treat as ovarian cancer C, if good performance status Group performance status, histology, number of metastatic sites, and neutrophil-lymphocyte ratio. Future prospective trials using this prognostic model are warranted. Clinically, some CUP diagno­ ses fall into a favorable prognostic subset. Others, including those with disseminated CUP, have a more unfavorable prognosis. TREATMENT OF FAVORABLE CUP SUBSETS Women with Isolated Axillary Adenopathy  Women with isolated axillary adenopathy with adenocarcinoma or carcinoma are usually treated for stage II or III breast cancer based on pathologic findings. These patients should undergo a breast MRI if mammogram and ultrasound are negative. Radiation therapy to the ipsilateral breast is indicated if the MRI of the breast is positive. Chemotherapy and/ or hormonal therapy are indicated based on patient’s age (pre­ menopausal or postmenopausal), nodal disease bulk, and hormone receptor and HER2 status (Chap. 84). It is important to verify that the pathology suggests a breast cancer profile (morphology, IHC breast markers including estrogen receptor, mammaglobin, GCDFP-15, GATA3, HER2 gene expression) before embarking on a breast cancer therapeutic program. Women with Peritoneal Carcinomatosis  The term primary peri­ toneal papillary serous carcinoma (PPSC) has been used to describe CUP with carcinomatosis with the pathologic and laboratory (elevated CA-125 antigen) characteristics of ovarian cancer but no ovarian primary tumor identified on transvaginal sonography or laparotomy. Studies suggest that ovarian cancer and PPSC, which are both of müllerian origin, have similar gene expression profiles. Like patients with ovarian cancer, patients with PPSC are candi­ dates for cytoreductive surgery, followed by adjuvant taxane- and platinum-based chemotherapy. In one retrospective study of 258 women with peritoneal carcinomatosis who had undergone cytoreductive surgery and chemotherapy, 22% of patients had a complete response to chemotherapy; the median survival duration was 18 months (range 11–24 months). However, not all peritoneal carcinomatosis in women is PPSC. Careful pathologic evaluation can help diagnose a colon cancer profile (CDX-2+, CK20+, CK7−) or a pancreaticobiliary cancer or even a mislabeled peritoneal mesothe­ lioma (calretinin, D2-40 positive; BerEp4, MOC-31 negative). Poorly Differentiated Carcinoma with Midline Adenopathy (Chap. 93)  Men with poorly differentiated or undifferentiated carcinoma who present with midline adenopathy should be evalu­ ated for extragonadal germ cell malignancy. If diagnosed and treated as such, they often experience a good response to treatment with platinum-based combination chemotherapy. Response rates of >50% have been noted, and long-term survival rates of 10–15% have been reported. Older patients, especially smokers, who present with mediastinal adenopathy are more likely to have a lung or head and neck cancer profile. Neuroendocrine Cancer (Chap. 89)  Low-grade neuroendocrine tumor (NET) often has an indolent course, and treatment decisions are based on symptoms and tumor bulk. Urine 5-HIAA and serum chromogranin may be elevated and can be followed as markers. Often the patient is treated with somatostatin analogues alone for hormone-related symptoms (diarrhea, flushing, nausea). Specific local therapies or systemic therapy would only be indicated if the patient is symptomatic with local pain secondary to significant growth of the metastasis or the hormone-related symptoms are not controlled with endocrine therapy. Novel therapy options have demonstrated benefit in patients with low-grade NET, including sunitinib (which targets the vascular endothelial growth factor pathway), everolimus (which inhibits the mammalian target of rapamycin), and lutetium-177 dotatate (a somatostatin peptide receptor radioligand). Patients with high-grade NET are treated with platinum-based doublet therapy; 20–25% show a complete response, and up to 10% patients with limited/oligo presentations survive for >5 years. Some degree of neuroendocrine differentiation can be seen in diverse poorly differentiated carcinomas. Squamous Cell Carcinoma Presenting as Neck Adenopathy  Patients with early-stage squamous cell carcinoma involving the cervical lymph nodes are candidates for node dissection and radiation therapy, which can result in long-term survival. The role of che­ motherapy in these patients is undefined, although chemoradiation therapy or induction chemotherapy is often used and is beneficial in bulky N2/N3 lymph node disease. Solitary Metastatic Sites  Patients with solitary metastases can also experience good treatment outcomes. Some patients who pres­ ent with locoregional disease are candidates for aggressive trimo­ dality (chemotherapy, radiation, and surgery) management—both prolonged disease-free survival and, occasionally, cure are possible. Men with Blastic Skeletal Metastases and Elevated PSA (Chap. 92)  Blastic bone-only metastasis is a rare presentation, and elevated serum PSA or tumor staining with PSA may provide con­ firmatory evidence of prostate cancer in these patients. Those with elevated levels are candidates for hormonal or other therapy for prostate cancer, although it is important to rule out other primary tumors (lung most common). MANAGEMENT OF DISSEMINATED CUP Patients who present with liver, brain, and adrenal metastatic disease usually have a poor prognosis. Patients with peritoneal carcinomatosis secondary to metastatic adenocarcinoma have a broad differential diagnosis, which includes mainly gastrointestinal cancers including gastric, appendiceal, colon, and pancreaticobili­ ary cancers. CHAPTER 97 Traditionally, platinum-based combination chemotherapy regi­ mens have been used to treat CUP. Several broadly used regimens have been studied in the past two decades; these include paclitaxelcarboplatin, gemcitabine-cisplatin, gemcitabine-oxaliplatin, and irinotecan and fluoropyrimidine-based therapies. These chemo­ therapeutic agents used as empiric regimens have shown response rates of 25–40%, and their use obtains median survival times of 6–13 months. Carcinoma of Unknown Primary Outside of favorable subsets, there is a small group of patients with a “definitive” IHC profile. These patients usually have a single diagnosis based on their clinicopathologic presentation and are often treated for the putative primary tumor. This does not guar­ antee a response, although it increases the probability of response when select drugs are chosen from a class of drugs known to be effective in that cancer type. Efforts should be made to search for biomarkers of response to tumor-agnostic effective therapies such as immunotherapy for MSI-H/dMMR tumors. Patients who do not fall into those categories are candidates for broad-spectrum platinum-based regimens, clinical trials, and additional trial-based genomic and proteomic tests. Today, we do not have many effective drugs for several CUP cancer profiles, and treatments overlap for some cancers. Immunotherapy has been an area of active interest due to robust and durable responses in cancers with known prima­ ries and has shown some activity in CUP. However, biomarkers of response and immune-sensitive subsets need to be defined within CUP. SUMMARY Patients with CUP should undergo a directed diagnostic search for the primary tumor based on clinical and pathologic data. Subsets of patients have prognostically favorable disease, as defined by clinical or histologic criteria, and may substantially benefit from aggressive treatment; in these patients, prolonged survival can be expected. How­ ever, for most patients who present with advanced CUP, the prognosis remains poor with early resistance to available cytotoxic therapy. The current focus has shifted away from empirical chemotherapeutic trials to understanding the metastatic phenotype, tissue of origin profiling in select patients, and next-generation sequencing to identify actionable mutations in CUP patients. As novel therapies evolve in cancers with known primaries, investigations to assess their value in CUP will likely have a positive impact on management of CUP patients. # 27 - 98 Paraneoplastic Syndromes- Endocrinologic-Hematologic ### 98 Paraneoplastic Syndromes: Endocrinologic/Hematologic ■ ■FURTHER READING Gatalica Z et al: Comprehensive analysis of cancers of unknown pri­ mary for the biomarkers of response to immune checkpoint blockade therapy. Eur J Cancer 94:179, 2018. Hayashi H et al: Randomized phase II trial comparing site-specific treatment based on gene expression profiling with carboplatin and paclitaxel for patients with cancer of unknown primary site. J Clin Oncol 37:570, 2019. Hayashi H et al: Site-specific and targeted therapy based on molecu­ lar profiling by next-generation sequencing for cancer of unknown primary site: A nonrandomized phase 2 clinical trial. JAMA Oncol 6:1, 2020. Huey R et al: Feasibility and value of genomic profiling in cancer of unknown primary: Real-world evidence from prospective profiling study. J Natl Cancer Inst 115:994, 2023. Kato S et al: Utility of genomic analysis in circulating tumor DNA from patients with carcinoma of unknown primary. Cancer Res 77: 4238, 2017. National Comprehensive Cancer Network: Occult Primary (Cancer of Unknown Primary) version 2.2017, October 2016. https:// www.nccn.org/guidelines/guidelines-detail?category=1&id=1451. Raghav K et al: Cancer of unknown primary in adolescents and young adults: Clinicopathological features, prognostic factors and survival outcomes. PLoS One 11:e0154985, 2016. Raghav K et al: Development and validation of a novel nomogram for PART 4 Oncology and Hematology individualized prediction of survival in cancer of unknown primary. Clin Cancer Res 27:3414, 2021. Raghav K et al: Efficacy of pembrolizumab in patients with advanced cancer of unknown primary (CUP): A phase 2 non-randomized clini­ cal trial. J Immunother Cancer 10:e004822, 2022. Ross JS et al: Comprehensive genomic profiling of carcinoma of unknown primary site: New routes to targeted therapies. JAMA Oncol 1:40, 2015. Varadhachary GR, Raber MN: Cancer of unknown primary site. N Engl J Med 371:757, 2014. J. Larry Jameson, Dan L. Longo Paraneoplastic Syndromes: Endocrinologic/Hematologic Neoplastic cells can produce a variety of substances that can alter the physiology of hormonal, hematologic, dermatologic, rheumatologic, renal, and neurologic systems. Paraneoplastic syndromes refer to the disorders that accompany benign or malignant tumors but are not directly related to mass effects or invasion. Tumors of neuroendo­ crine origin, such as small-cell lung carcinoma (SCLC) and carci­ noids, are common causes of paraneoplastic syndromes, but these syndromes are associated with many types of tumors that produce peptide hormones, cytokines, and growth factors and induce the production of antibodies. Studies of the prevalence of paraneoplastic syndromes indicate that they are more common than is generally appreciated. The signs, symptoms, and metabolic alterations associ­ ated with paraneoplastic disorders are easily overlooked in the con­ text of a malignancy and its treatment. Consequently, atypical clinical manifestations in a patient with cancer should prompt consideration of a paraneoplastic syndrome. The most common hormonal and hematologic syndromes associated with underlying neoplasia will be discussed here. ENDOCRINE PARANEOPLASTIC SYNDROMES Etiology  Hormones can be produced from eutopic or ectopic sources. Eutopic refers to the expression of a hormone from its normal tissue of origin, whereas ectopic refers to hormone production from an atypical tissue source. For example, adrenocorticotropic hormone (ACTH) is expressed eutopically by the corticotrope cells of the anterior pituitary, but it can be expressed ectopically in SCLC. Many hormones are produced at low levels from tissues other than the clas­ sic endocrine source. Thus, ectopic expression is often a quantitative change rather than an absolute change in tissue expression. Neverthe­ less, the term ectopic expression is firmly entrenched and conveys the abnormal physiology associated with hormone production by neoplas­ tic cells. In addition to high levels of hormones, ectopic expression is often characterized by abnormal regulation of hormone production (e.g., defective feedback control in ectopic ACTH) and peptide pro­ cessing (resulting in large, unprocessed precursor peptide such as proopiomelanocortin [POMC]). Many different molecular mechanisms can cause ectopic hormone production. In rare instances, genetic rearrangements account for aberrant hormone expression. For example, translocation of the para­ thyroid hormone (PTH) gene can result in high levels of PTH expres­ sion in tissues other than the parathyroid gland because the genetic rearrangement brings the PTH gene under the control of atypical regulatory elements. A related phenomenon is well documented in many forms of leukemia and lymphoma, in which somatic genetic rear­ rangements confer a growth advantage and alter cellular differentiation and function. Although genetic rearrangements cause selected cases of ectopic hormone production, this mechanism is rare, as many tumors are associated with excessive production of numerous peptides. Cellu­ lar dedifferentiation probably underlies most cases of ectopic hormone production. Many cancers are poorly differentiated, and certain tumor products, such as human chorionic gonadotropin (hCG), PTH–related protein (PTHrP), and α-fetoprotein, are characteristic of gene expres­ sion at earlier developmental stages. In contrast, the propensity of certain cancers to produce particular hormones (e.g., squamous cell carcinomas produce PTHrP) suggests that dedifferentiation is partial or that selective pathways are derepressed. These expression profiles probably reflect epigenetic modifications that alter transcriptional repression, microRNA expression, and other pathways that govern cell differentiation. Ectopic hormone production might be considered merely epiphe­ nomenon associated with cancer if it did not cause clinical manifes­ tations. Excessive and unregulated production of hormones such as ACTH, PTHrP, and vasopressin can lead to substantial morbidity and complicate the cancer treatment plan. Moreover, the paraneoplastic endocrinopathies may be a presenting clinical feature of underlying malignancy and prompt the search for an unrecognized tumor. General features that confirm cancer-associated ectopic hormone syndromes include: (1) excess hormone production from an atypical tissue source; (2) documentation of tumor hormone production based on immunostaining, mRNA production, or hormone secretion in vitro; (3) hormone gradient across the tumor vascular supply; and (4) resolution or decline of hormone levels after reduction of tumor mass. Imaging studies, including computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), and octreotide scintigraphy also play an important role in the detection and characterization of tumors associated with paraneoplastic syndromes, particularly when endocrine clinical manifestations precede a cancer diagnosis (i.e., ectopic ACTH in lung cancer). Treatment of the under­ lying tumor is the mainstay of all paraneoplastic endocrine syndromes. Depending on the hormone produced, specific therapies can be used (see below) to ameliorate symptoms but rarely influence overall sur­ vival or cancer progression. A large number of paraneoplastic endocrine syndromes have been described, linking overproduction of particular hormones with specific types of tumors. However, certain recurring syndromes emerge from this group (Table 98-1). The most common paraneoplastic endocrine TABLE 98-1  Paraneoplastic Syndromes Caused by Ectopic Hormone Production PARANEOPLASTIC SYNDROME ECTOPIC HORMONE TYPICAL TUMOR TYPESa Common Hypercalcemia of malignancy Parathyroid hormone–related protein (PTHrP) Squamous cell (head and neck, lung, skin), breast, genitourinary, gastrointestinal; osteolytic metastases 1,25-Dihydroxyvitamin D Lymphomas Parathyroid hormone (PTH) (rare) Lung, ovary Prostaglandin E2 (PGE2) (rare) Renal, lung Syndrome of inappropriate antidiuretic hormone secretion (SIADH) Vasopressin Lung (squamous, small cell), gastrointestinal, genitourinary, breast, ovary Cushing’s syndrome Adrenocorticotropic hormone (ACTH) Lung (small cell, bronchial carcinoid, adenocarcinoma, squamous), thymus, pancreatic islet, medullary thyroid carcinoma, pheochromocytoma Corticotropin-releasing hormone (CRH) (rare) Pancreatic islet, carcinoid, lung, prostate Ectopic expression of gastric inhibitory peptide (GIP), luteinizing hormone (LH)/human chorionic gonadotropin (hCG), other G protein–coupled receptors (rare) Less Common Non–islet cell hypoglycemia Insulin-like growth factor type II (IGF-II) Mesenchymal tumors, sarcomas, adrenal, hepatic, gastrointestinal, kidney, prostate Insulin (rare) Cervix (small-cell carcinoma) Male feminization hCGb Testis (embryonal, seminomas), germinomas, choriocarcinoma, lung, hepatic, pancreatic islet Diarrhea or intestinal hypermotility Calcitoninc Lung, colon, breast, medullary thyroid carcinoma Vasoactive intestinal peptide (VIP) Pancreas, pheochromocytoma, esophagus Rare Oncogenic osteomalacia Fibroblast growth factor 23 (FGF23) or phosphatonin Hemangiopericytomas, osteoblastomas, fibromas, sarcomas, giant cell tumors, prostate, lung Acromegaly Growth hormone–releasing hormone (GHRH) Pancreatic islet, bronchial, and other carcinoids Growth hormone (GH) Lung, pancreatic islet Hyperthyroidism Thyroid-stimulating hormone (TSH) Hydatidiform mole, embryonal tumors, struma ovarii Hypertension Renin Juxtaglomerular tumors, kidney, lung, pancreas, ovary Consumptive hypothyroidism Type 3 deiodinase Hepatic and other hemangiomas Cancer immunotherapy associated autoimmune diseases Autoimmune hormone deficiencies Thyroiditis, Graves’ disease aOnly the most common tumor types are listed. For most ectopic hormone syndromes, an extensive list of tumors has been reported to produce one or more hormones. bhCG is produced eutopically by trophoblastic tumors. Certain tumors produce disproportionate amounts of the hCG α or hCG β subunit. High levels of hCG rarely cause hyperthyroidism because of weak binding to the TSH receptor. cCalcitonin is produced eutopically by medullary thyroid carcinoma and is used as a tumor marker. Abbreviations: CTLA-4, cytotoxic T lymphocyte-associated protein-4; PD-1, programmed cell death protein 1; PD-L1, programmed death ligand 1. syndromes include hypercalcemia from overproduction of PTHrP and other factors, hyponatremia from excess vasopressin, and Cushing’s syndrome from ectopic ACTH. ■ ■HYPERCALCEMIA CAUSED BY ECTOPIC PRODUCTION OF PTHRP (See also Chap. 422). Etiology  Humoral hypercalcemia of malignancy (HHM) occurs in up to 20% of patients with cancer. HHM is most common in cancers of the lung, head and neck, skin, esophagus, breast, and genitourinary tract and in multiple myeloma and lymphomas, as well as metastases associated with these, and other cancers. There are several distinct humoral causes of HHM, but it is caused most commonly by overpro­ duction of PTHrP. In addition to acting as a circulating humoral factor, bone metastases (e.g., breast, multiple myeloma) may produce PTHrP and other chemokines, leading to local osteolysis and hypercalcemia. PTHrP may also affect the initiation and progression of tumors by act­ ing through pro-survival and chemokine pathways. PTHrP is structurally related to PTH and binds to the PTH receptor, explaining the similar biochemical features of HHM and hyperpara­ thyroidism. PTHrP plays a key physiologic role in skeletal development and regulates cellular proliferation and differentiation in other tissues, including skin, bone marrow, breast, and hair follicles. The mecha­ nism of PTHrP induction in malignancy is incompletely understood; Macronodular adrenal hyperplasia CHAPTER 98 Paraneoplastic Syndromes: Endocrinologic/Hematologic Cancers treated with immunotherapy, particularly anti–CTLA-4, PD-1, PD-L1 however, tumor-bearing tissues commonly associated with HHM nor­ mally produce PTHrP during development or cell renewal. Hypometh­ ylation of the PTHLH locus, which encodes PTHrP, suggests a role for epigenetic factors in upregulating PTHrP production. PTHrP expres­ sion is stimulated by hedgehog pathways and Gli transcription factors that are active in many malignancies. Transforming growth factor β (TGF-β), which is produced by many tumors, also stimulates PTHrP. Mutations in certain oncogenes, such as Ras, also can activate PTHrP expression, as does loss of the tumor suppressor, p53. In addition to its role in HHM, the PTHrP pathway may also provide a potential target for therapeutic intervention to impede cancer growth. Another relatively common cause of HHM is excess production of 1,25-dihydroxyvitamin D. Like granulomatous disorders associated with hypercalcemia, lymphomas can produce an enzyme that converts 25-hydroxyvitamin D to the more active 1,25-dihydroxyvitamin D, leading to enhanced gastrointestinal calcium absorption. Other causes of HHM include tumor-mediated production of osteolytic cytokines and inflammatory mediators. Clinical Manifestations  The typical presentation of HHM is a patient with a known malignancy who is found to be hypercalcemic on routine laboratory tests. Less often, hypercalcemia is the initial present­ ing feature of malignancy. Particularly when calcium levels are mark­ edly increased (>3.5 mmol/L [>14 mg/dL]), patients may experience fatigue, mental status changes, polyuria, dehydration, or symptoms of nephrolithiasis. Hypercalcemia can shorten ST segments and QT inter­ vals, as well as bundle branch blocks and bradyarrhythmias. Diagnosis  Features that favor HHM, as opposed to primary hyper­ parathyroidism, include known malignancy, recent onset of hypercal­ cemia, and very high serum calcium levels. Like hyperparathyroidism, hypercalcemia caused by PTHrP is accompanied by hypercalciuria and hypophosphatemia. Patients with HHM typically have metabolic alkalosis rather than hyperchloremic acidosis, as is seen in hyperpara­ thyroidism. In contrast to PTH, PTHrP does not appear to stimulate 1-α-hydroxylase and 1,25-dihydroxyvitamin D levels. Measurement of PTH is useful to exclude primary hyperparathyroidism; the PTH level should be suppressed in HHM. An elevated PTHrP level confirms the diagnosis, and it is increased in ~80% of hypercalcemic patients with cancer. 1,25-Dihydroxyvitamin D levels may be increased in patients with lymphoma. TREATMENT Humoral Hypercalcemia of Malignancy The management of HHM begins with removal of excess calcium in the diet, medications, or intravenous (IV) solutions. Saline rehydration (typically 200–500 mL/h) is used to dilute serum calcium and promote calciuresis; exercise caution in patients with cardiac, hepatic, or renal insufficiency. Forced diuresis with furo­ semide (20–80 mg IV in escalating doses) or other loop diuretics can enhance calcium excretion but provides relatively little value except in life-threatening hypercalcemia. When used, loop diuret­ ics should be administered only after complete rehydration and with careful monitoring of fluid balance. Oral phosphorus (e.g., 250 mg Neutra-Phos 3–4 times daily) should be given until serum phosphorus is >1 mmol/L (>3 mg/dL). Bisphosphonates such as zoledronate (4–8 mg IV), pamidronate (60–90 mg IV), and etidro­ nate (7.5 mg/kg per day orally [PO] for 3–7 consecutive days) can reduce serum calcium within 1–2 days and suppress calcium release for several weeks. Bisphosphonate infusions can be repeated, or oral bisphosphonates can be used for chronic treatment. Denosumab (120 mg subcutaneously [SC] weekly for 4 weeks and then monthly) can be used in patients who do not respond adequately to bisphos­ phonates. It acts as a decoy receptor for RANK ligand to mitigate stimulation of osteoclasts. Cinacalcet (30 mg PO bid to 90 mg PO qid) stimulates calcium-sensing receptors to suppress PTH secre­ tion and is therefore applicable in parathyroid carcinoma and rare cases of ectopic PTH-producing tumors. Hypercalcemia associated with lymphomas, multiple myeloma, or leukemia may respond to glucocorticoid treatment (e.g., prednisone 40–100 mg PO in four divided doses). Dialysis should be considered in severe hypercal­ cemia when saline hydration and bisphosphonate treatments are not possible or are too slow in onset. Previously used agents such as calcitonin and mithramycin have little utility now that bisphospho­ nates and other agents are available. PART 4 Oncology and Hematology ■ ■ECTOPIC VASOPRESSIN: TUMOR-ASSOCIATED SYNDROME OF INAPPROPRIATE ANTIDIURETIC HORMONE (See also Chap. 56). Etiology  Vasopressin is an antidiuretic hormone normally pro­ duced by the posterior pituitary gland. Ectopic vasopressin production by tumors is a common cause of the syndrome of inappropriate antidi­ uretic hormone (SIADH), occurring in at least half of patients with SCLC. SIADH also can be caused by a number of nonneoplastic condi­ tions, including central nervous system (CNS) trauma, infections, and medications (Chap. 398). Compensatory responses to SIADH, such as decreased thirst, may mitigate the development of hyponatremia. How­ ever, with prolonged production of excessive vasopressin, the osmostat controlling thirst and hypothalamic vasopressin secretion may become reset. In addition, intake of free water, orally or intravenously, can quickly worsen hyponatremia because of reduced renal diuresis. Tumors with neuroendocrine features, such as SCLC and carcinoids, are the most common sources of ectopic vasopressin production, but it also occurs in other forms of lung cancer and with CNS lesions, head and neck cancer, and genitourinary, gastrointestinal, and ovarian cancers. The mechanism of activation of the vasopressin gene in these tumors is unknown, but the frequent concomitant expression of the adjacent oxytocin gene suggests derepression of this locus. Clinical Manifestations  Most patients with ectopic vasopressin secretion are asymptomatic and are identified because of the presence of hyponatremia on routine chemistry testing. Symptoms may include weakness, lethargy, nausea, confusion, depressed mental status, and seizures. The severity of symptoms reflects the rapidity of onset as well as the severity of hyponatremia. Hyponatremia usually develops slowly but may be exacerbated by the administration of IV fluids or the insti­ tution of new medications. Diagnosis  The diagnostic features of ectopic vasopressin produc­ tion are the same as those of other causes of SIADH (Chaps. 56 and 398). Hyponatremia and reduced serum osmolality occur in the set­ ting of an inappropriately normal or increased urine osmolality. Urine sodium excretion is normal or increased unless volume depletion is present. Other causes of hyponatremia should be excluded, including renal, adrenal, or thyroid insufficiency. Physiologic sources of vaso­ pressin stimulation (CNS lesions, pulmonary disease, nausea), adaptive circulatory mechanisms (hypotension, heart failure, hepatic cirrho­ sis), and medications, including many chemotherapeutic agents, also should be considered as possible causes of hyponatremia. Vasopressin measurements are not usually necessary to make the diagnosis. TREATMENT Ectopic Vasopressin: Tumor-Associated SIADH Most patients with ectopic vasopressin production develop hypo­ natremia over several weeks or months. The disorder should be corrected gradually unless mental status is altered or there is risk of seizures. Rapid correction can cause brain dehydration and central pontine myelinolysis. Treatment of the underlying malignancy may reduce ectopic vasopressin production, but this response is slow if it occurs at all. Fluid restriction to less than urine output, plus insensible losses, is often sufficient to correct hyponatremia partially. However, strict monitoring of the amount and types of liquids consumed or administered intravenously is required for fluid restriction to be effective. Salt tablets and saline are not helpful unless volume depletion is also present. Demeclocycline (150–300 mg orally 3–4 times daily) can be used to inhibit vasopressin action on the renal distal tubule, but its onset of action is relatively slow (1–2 weeks), and it has largely been supplanted by newer vasopres­ sin receptor antagonists. The vaptan class of drugs acts by inhibiting vasopressin receptors (V1A, V1B, V2) in the renal collecting ducts. Nonpeptide V2-receptor antagonists, tolvaptan (15 mg PO daily) or conivaptan (20–120 mg PO bid or 10–40 mg IV), are particu­ larly effective when used in combination with fluid restriction in euvolemic hyponatremia. Severe hyponatremia (Na <115 meq/L) or mental status changes may require treatment with hypertonic (3%) or normal saline infusion together with furosemide to enhance free water clearance. The rate of sodium correction should be slow (0.5–1 meq/L per hour) to prevent rapid fluid shifts and the possible development of central pontine myelinolysis. ■ ■CUSHING’S SYNDROME CAUSED BY ECTOPIC ACTH PRODUCTION (See also Chap. 398). Etiology  Ectopic ACTH production accounts for 10–20% of cases of Cushing’s syndrome. The syndrome is particularly common in neuroendocrine tumors. SCLC is the most common cause of ectopic ACTH, followed by bronchial and thymic carcinoids, islet cell tumors, other carcinoids, and pheochromocytomas. Ectopic ACTH production is caused by increased expression of the proopiomelanocortin (POMC) gene, which encodes ACTH, along with melanocyte-stimulating hormone (MSH), β-lipotropin, and several other peptides. In many tumors, there is abundant but aberrant expression of the POMC gene from an internal promoter, proximal to the third exon, which encodes ACTH. However, because this product lacks the signal sequence nec­ essary for protein processing, it is not secreted. Increased production of ACTH arises instead from less abundant, but unregulated, POMC expression from the same promoter site used in the pituitary. Because tumors lack many of the enzymes needed to process the POMC poly­ peptide, it is typically released as multiple large, biologically inactive fragments along with relatively small amounts of fully processed, active ACTH. Rarely, corticotropin-releasing hormone (CRH) is produced by pan­ creatic islet cell tumors, SCLC, medullary thyroid cancer, carcinoids, or prostate cancer. When levels are high enough, CRH can cause pituitary corticotrope hyperplasia and Cushing’s syndrome. Tumors that pro­ duce CRH sometimes also produce ACTH, raising the possibility of a paracrine mechanism for ACTH production. A distinct mechanism for ACTH-independent Cushing’s syndrome involves ectopic expression of various G protein–coupled receptors in adrenal nodules. Ectopic expression of the gastric inhibitory peptide (GIP) receptor is the best-characterized example of this mechanism. In this case, meals induce GIP secretion, which inappropriately stimulates adrenal growth and glucocorticoid production. Clinical Manifestations  The clinical features of hypercorti­ solemia are detected in only a fraction of patients with documented ectopic ACTH production. Patients with ectopic ACTH syndrome gen­ erally exhibit less marked weight gain and centripetal fat redistribution, probably because the exposure to excess glucocorticoids is relatively brief and because cachexia reduces the propensity for weight gain and fat deposition. The ectopic ACTH syndrome is associated with several clinical features that distinguish it from other causes of Cush­ ing’s syndrome (e.g., pituitary adenomas, adrenal adenomas, iatrogenic glucocorticoid excess). The metabolic manifestations of ectopic ACTH syndrome are dominated by fluid retention and hypertension, hypo­ kalemia, metabolic alkalosis, glucose intolerance, and occasionally steroid psychosis. The very high ACTH levels often cause increased pigmentation, reflecting increased activity of MSH derived from the POMC precursor peptide. The extraordinarily high glucocorticoid levels in patients with ectopic sources of ACTH can lead to marked skin fragility and easy bruising. In addition, the high cortisol levels often overwhelm the renal 11β-hydroxysteroid dehydrogenase type II enzyme, which normally inactivates cortisol and prevents it from binding to renal mineralocorticoid receptors. Consequently, in addi­ tion to the excess mineralocorticoids produced by ACTH stimulation of the adrenal gland, high levels of cortisol exert activity through the mineralocorticoid receptor, leading to severe hypokalemia. Diagnosis  The diagnosis of ectopic ACTH syndrome is usually not difficult in the setting of a known malignancy. Urine-free cortisol levels fluctuate but are typically greater than two to four times normal, and the plasma ACTH level is usually >22 pmol/L (>100 pg/mL). A sup­ pressed ACTH level excludes this diagnosis and indicates an ACTHindependent cause of Cushing’s syndrome (e.g., adrenal or exogenous glucocorticoid). In contrast to pituitary sources of ACTH, most ectopic sources of ACTH do not respond to glucocorticoid suppression. There­ fore, high-dose dexamethasone (8 mg PO) suppresses 8:00 a.m. serum cortisol (50% decrease from baseline) in ~80% of pituitary ACTHproducing adenomas but fails to suppress ectopic ACTH in ~90% of cases. Bronchial and other carcinoids are well-documented exceptions to these general guidelines, as these ectopic sources of ACTH may exhibit feedback regulation indistinguishable from pituitary adeno­ mas, including suppression by high-dose dexamethasone, and ACTH responsiveness to adrenal blockade with metyrapone. If necessary, petrosal sinus catheterization can be used to evaluate a patient with ACTH-dependent Cushing’s syndrome when the source of ACTH is unclear. After CRH stimulation, a 3:1 petrosal sinus:peripheral ACTH ratio strongly suggests a pituitary ACTH source. Imaging studies (CT or MRI) are also useful in the evaluation of suspected carcinoid lesions, allowing biopsy and characterization of hormone production using special stains. If available, PET scans or octreotide scintigraphy may identify some sources of ACTH production. TREATMENT Cushing’s Syndrome Caused by Ectopic ACTH Production The morbidity associated with the ectopic ACTH syndrome can be substantial. Patients may experience depression or personality changes because of extreme cortisol excess. Metabolic derange­ ments, including diabetes mellitus and hypokalemia, can worsen fatigue. Poor wound healing and predisposition to infections can complicate the surgical management of tumors, and opportunis­ tic infections caused by organisms such as Pneumocystis carinii and mycoses are often the cause of death in patients with ectopic ACTH production. These patients have increased risk of venous thromboembolism, reflecting the combination of malignancy and altered coagulation factor profiles. Depending on prognosis and treatment plans for the underlying malignancy, measures to reduce cortisol levels are often indicated. Treatment of the underlying malignancy may reduce ACTH levels but is rarely sufficient to reduce cortisol levels to normal. Adrenalectomy is not practical for most of these patients but should be considered during surgery for the malignancy or if the underlying tumor is not resectable and the prognosis is otherwise favorable (e.g., carcinoid). Medical therapy with ketoconazole (300–600 mg PO bid), metyrapone (250–500 mg PO every 6 h), mitotane (3–6 g PO in four divided doses, tapered to maintain low cortisol production), etomidate (0.1–0.3 mg/kg/h IV), or other agents that block steroid synthesis or action is often the most practical strategy for managing the hypercorti­ solism associated with ectopic ACTH production. Glucocorticoid replacement should be provided to prevent adrenal insufficiency (Chap. 398). Unfortunately, many patients eventually progress despite medical blockade. Mifepristone (200–1000 mg PO qd) inhibits both glucocorticoid and progesterone receptors, has rapid onset of action, and improves glucose intolerance and hypertension in a subset of patients. ACTH-neutralizing antibodies and ACTH recep­ tor blockers are under investigation, as are selective inhibitors of the glucocorticoid receptor. CHAPTER 98 Paraneoplastic Syndromes: Endocrinologic/Hematologic ■ ■TUMOR-INDUCED HYPOGLYCEMIA CAUSED BY EXCESS PRODUCTION OF INSULIN-LIKE GROWTH FACTOR TYPE II (See also Chap. 418) Mesenchymal tumors, hemangiopericytomas, hepatocellular tumors, adrenal carcinomas, and a variety of other large tumors have been reported to produce excessive amounts of insulinlike growth factor type II (IGF-II) precursor, which binds weakly to insulin receptors and more strongly to IGF-I receptors, leading to insulin-like actions. The gene encoding IGF-II resides on chromosome 11p15, a locus that is normally imprinted (that is, expression is exclu­ sively from a single parental allele). Biallelic expression of the IGF-II gene occurs in a subset of tumors, suggesting loss of methylation and loss of imprinting as a mechanism for gene induction. In addition to increased IGF-II production, IGF-II bioavailability is increased due to complex alterations in circulating binding proteins. Increased IGF-II suppresses growth hormone (GH) and insulin, resulting in reduced IGF binding protein 3 (IGFBP-3), IGF-I, and acid-labile subunit (ALS). The reduction in ALS and IGFBP-3, which normally sequester IGF-II, causes it to be displaced to a small circulating complex that has greater access to insulin target tissues. For this reason, circulating IGF-II levels may not be markedly increased despite causing hypoglycemia. In addi­ tion to IGF-II–mediated hypoglycemia, tumors may occupy enough of the liver to impair gluconeogenesis. In most cases, a tumor causing hypoglycemia is clinically apparent (usually >10 cm in size), and hypoglycemia develops in association with fasting. As with other causes of hypoglycemia, patients may present with sweating, tremors, palpitations, confusion, seizures, or coma. The diagnosis is made by documenting low serum glucose and suppressed insulin levels in association with symptoms of hypoglyce­ mia. Serum IGF-II levels may not be increased (IGF-II assays may not detect IGF-II precursors), but an elevated IGF-II/IGF-I ratio greater than 10:1 is suggestive. Increased IGF-II mRNA expression is found in most of these tumors. Any medications associated with hypoglycemia should be eliminated. Treatment of the underlying malignancy, if pos­ sible, may reduce the predisposition to hypoglycemia. Frequent meals and IV glucose, especially during sleep or fasting, are often necessary to prevent hypoglycemia. Glucagon, recombinant GH, and glucocorti­ coids have also been used to enhance glucose production. Antibodies that inhibit IGF-II action are under development. ■ ■HUMAN CHORIONIC GONADOTROPIN hCG is composed of α and β subunits and can be produced as intact hormone, which is biologically active, or as uncombined biologically inert subunits. Ectopic production of intact hCG occurs most often in association with testicular embryonal tumors, germ cell tumors, extragonadal germinomas, lung cancer, hepatoma, and pancreatic islet tumors. Eutopic production of hCG occurs with trophoblastic malignancies. hCG α subunit production is particularly common in lung cancer and pancreatic islet cancer. In men, high hCG levels stimulate steroidogenesis and aromatase activity in testicular Leydig cells, resulting in increased estrogen production and the development of gynecomastia. Precocious puberty in boys or gynecomastia in men should prompt measurement of hCG and consideration of a testicular tumor or another source of ectopic hCG production. Most women are asymptomatic. hCG is easily measured. Treatment should be directed at the underlying malignancy. PART 4 Oncology and Hematology ■ ■ONCOGENIC OSTEOMALACIA Hypophosphatemic oncogenic osteomalacia, also called tumor-induced osteomalacia (TIO), is caused by excessive production of fibroblast growth factor 23 (FGF23), previously referred to as phosphotonin. Oncogenic osteomalacia is characterized by markedly reduced serum phosphorus and renal phosphate wasting, leading to muscle weakness, bone pain, and osteomalacia. Serum calcium and PTH levels are normal. FGF23 inhibits the renal conversion of 25-hydroxyvitamin D to 1,25-dihydroxyvitamin D, resulting in low levels of 1,25-dihydroxyvitamin D. Oncogenic osteo­ malacia is usually caused by benign mesenchymal tumors, such as hemangiopericytomas, fibromas, and giant cell tumors, often of the skeletal extremities or head. It has also been described in sarcomas and in patients with prostate or lung cancer. Resection of the tumor reverses the disorder, confirming its humoral basis. FGF23 levels are increased in some, but not all, patients with osteogenic osteomalacia. FGF23 forms a ternary complex with the klotho protein and renal FGF receptors to reduce renal phosphate reabsorption. Treatment involves removal of the tumor, if possible, and supplementation with phosphate and vitamin D. Octreotide treatment reduces phosphate wasting in some patients with tumors that express somatostatin receptor subtype 2. Octreotide scans may also be useful in detecting these tumors. A human monoclonal antibody against FGF23, burosumab (0.5 mg/kg every 4 weeks) has been approved for the treatment of osteogenic osteomala­ cia. If needed, it can be increased to 2 mg/kg every 2 weeks. Burosumab improves metabolic features of the disease and may improve bone structure and fracture risk, but these outcomes are still being evaluated. The calcium-sensing receptor agonist cinacalcet has been effective in some patients, apparently by reducing PTH-mediated phosphaturia. FGF receptor inhibitors hold promise as future therapies targeted either to pathways that stimulate FGR23 production (e.g., FGFR1) or inhibit its action (e.g., FGF23 receptor). ■ ■CONSUMPTIVE HYPOTHYROIDISM Newborns with hepatic hemangiomas can develop a rare form of hypo­ thyroidism caused by overexpression of type 3 deiodinase (D3), an enzyme that degrades and inactivates thyroxine (T4) and triiodothyro­ nine (T3). The very high expression of D3 and consumption of thyroid hormones apparently outstrip the thyroid gland’s rate of hormone production. The disorder is characterized by low T4, low T3, high TSH, and markedly elevated reverse T3 (rT3), reflecting the degradation of T4 to rT3. In addition to treating the underlying hemangioma (rarely other tumor types), patients are treated with l-thyroxine replacement, titrated to normalize TSH. Steroids and propranolol may provide ben­ efit, perhaps by inhibiting growth factor pathways thought to stimulate D3 production. ■ ■CANCER IMMUNOTHERAPY-ASSOCIATED ENDOCRINOPATHIES (SEE ALSO CHAPS. 78, 401) Although not strictly a paraneoplastic endocrine syndrome, the intro­ duction of cancer immunotherapies, particularly immune checkpoint inhibitors (i.e., anti–CTLA-4, PD-1, PD-L1), is associated with a high incidence (~10%) of autoimmune endocrine disease. Hypophysitis and autoimmune thyroid diseases are most common, but autoimmune diabetes mellitus, adrenal insufficiency, hypoparathyroidism, and dia­ betes insipidus also occur. The mechanism of these autoimmune side effects remains unclear. CTLA-4 is expressed in the pituitary gland, likely explaining predisposition to anti–CTLA-4–associated hypophy­ sitis. Genetic predisposition and underlying endocrine autoimmunity likely play a role in thyroid and other endocrinopathies, becoming exacerbated following checkpoint inhibitor–induced immune activa­ tion. Autoimmune endocrine disease can emerge in the early weeks of immunotherapy but can also present after several months. At present, screening and prophylactic treatment are not routinely recommended. However, clinicians should be attuned to clinical or laboratory features of these disorders as they can be challenging to identify during can­ cer management. Treatment is similar to that of individual hormone deficiencies (Chaps. 391, 395, and 398). These endocrinopathies are generally irreversible and require lifelong hormone replacement. HEMATOLOGIC SYNDROMES The elevation of granulocyte, platelet, and eosinophil counts in most patients with myeloproliferative disorders is caused by the prolif­ eration of the myeloid elements due to the underlying disease rather than to a paraneoplastic syndrome. The paraneoplastic hematologic syndromes in patients with solid tumors are less well characterized than are the endocrine syndromes because the ectopic hormone(s) or cytokines responsible have not been identified in most of these tumors (Table 98-2). The extent of the paraneoplastic syndromes parallels the course of the cancer. With very rare exception, red cell, white cell, or platelet numbers are self-limited and not associated with symptomatic abnormalities. In some circumstances, elevations in platelet counts can be a marker that influences prognosis. By far, the most consequential hematologic abnormality in cancer patients is hypercoagulability. ■ ■ERYTHROCYTOSIS Ectopic production of erythropoietin by cancer cells causes most para­ neoplastic erythrocytosis. The ectopically produced erythropoietin TABLE 98-2  Paraneoplastic Hematologic Syndromes CANCERS TYPICALLY ASSOCIATED WITH SYNDROME SYNDROME PROTEINS Erythrocytosis Erythropoietin Renal cancers, hepatocarcinoma, cerebellar hemangioblastomas Granulocytosis G-CSF, GM-CSF, IL-6 Lung cancer, gastrointestinal cancer, ovarian cancer, genitourinary cancer, Hodgkin’s disease Thrombocytosis IL-6 Lung cancer, gastrointestinal cancer, breast cancer, ovarian cancer, lymphoma Eosinophilia IL-5 Lymphoma, leukemia, lung cancer Thrombophlebitis Unknown Lung cancer, pancreatic cancer, gastrointestinal cancer, breast cancer, genitourinary cancer, ovarian cancer, prostate cancer, lymphoma Abbreviations: G-CSF, granulocyte colony-stimulating factor; GM-CSF, granulocytemacrophage colony-stimulating factor; IL, interleukin. stimulates the production of red blood cells (RBCs) in the bone mar­ row and raises the hematocrit. Other lymphokines and hormones produced by cancer cells may stimulate erythropoietin release but have not been proved to cause erythrocytosis. Most patients with erythrocytosis have an elevated hematocrit (>52% in men, >48% in women) that is detected on a routine blood count. Approximately 3% of patients with renal cell cancer, 10% of patients with hepatoma, and 15% of patients with cerebellar heman­ gioblastomas have erythrocytosis. In most cases, the erythrocytosis is asymptomatic. Patients with erythrocytosis due to a renal cell cancer, hepatoma, or CNS cancer should have measurement of red cell mass. If the red cell mass is elevated, the serum erythropoietin level should be measured. Patients with a cancer that has been associated with erythrocytosis, ele­ vated erythropoietin levels, and no other explanation for erythrocytosis (e.g., hemoglobinopathy that causes increased O2 affinity; Chaps. 66 and 103) have the paraneoplastic syndrome. TREATMENT Erythrocytosis Successful resection of the cancer usually resolves the erythrocy­ tosis. If the tumor cannot be resected or treated effectively with radiation therapy or chemotherapy, phlebotomy may control any symptoms or risk related to erythrocytosis. ■ ■GRANULOCYTOSIS Approximately 30% of patients with solid tumors have granulocytosis (granulocyte count >8000/μL). In about half of patients with granu­ locytosis and cancer, the granulocytosis has an identifiable nonpara­ neoplastic etiology (e.g., infection, tumor necrosis, glucocorticoid administration). The other patients have proteins in urine and serum that stimulate the growth of bone marrow cells. Tumors and tumor cell lines from patients with lung, ovarian, and bladder cancers have been documented to produce granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GMCSF), and/or interleukin 6 (IL-6). However, the etiology of granulocy­ tosis has not been characterized in most patients. Patients with granulocytosis are nearly all asymptomatic, and the differential white blood cell count does not have a shift to immature forms of neutrophils. Granulocytosis occurs in 40% of patients with lung and gastrointestinal cancers, 20% of patients with breast cancer, 30% of patients with brain tumors and ovarian cancers, 20% of patients with Hodgkin’s disease, and 10% of patients with renal cell carcinoma. Patients with advanced-stage disease are more likely to have granulo­ cytosis than are those with early-stage disease. Paraneoplastic granulocytosis does not require treatment. The granulocytosis resolves when the underlying cancer is treated. ■ ■THROMBOCYTOSIS Some 35% of patients with thrombocytosis (platelet count >400,000/μL) have an underlying diagnosis of cancer. IL-6, a candidate molecule for the etiology of paraneoplastic thrombocytosis, stimulates the produc­ tion of platelets in vitro and in vivo. Some patients with cancer and thrombocytosis have elevated levels of IL-6 in plasma. Another can­ didate molecule is thrombopoietin, a peptide hormone that stimulates megakaryocyte proliferation and platelet production. The etiology of thrombocytosis has not been established in most cases. Patients with thrombocytosis are nearly all asymptomatic. Throm­ bocytosis is not clearly linked to thrombosis in patients with cancer. Thrombocytosis is present in 40% of patients with lung and gas­ trointestinal cancers; 20% of patients with breast, endometrial, and ovarian cancers; and 10% of patients with lymphoma. Patients with thrombocytosis are more likely to have advanced-stage disease and have a poorer prognosis than do patients without thrombocytosis. In ovarian cancer, IL-6 has been shown to directly promote tumor growth. Paraneoplastic thrombocytosis does not require treatment other than treatment of the underlying tumor. ■ ■EOSINOPHILIA Eosinophilia is present in ~1% of patients with cancer. Tumors and tumor cell lines from patients with lymphomas or leukemia may produce IL-5, which stimulates eosinophil growth. Activation of IL-5 transcription in lymphomas and leukemias may involve translocation of the long arm of chromosome 5, to which the genes for IL-5 and other cytokines map. Patients with eosinophilia are typically asymptomatic. Eosinophilia is present in 10% of patients with lymphoma, 3% of patients with lung cancer, and occasional patients with cervical, gastrointestinal, renal, and breast cancer. Patients with markedly elevated eosinophil counts (>5000/μL) can develop shortness of breath and wheezing. A chest radiograph may reveal diffuse pulmonary infiltrates from eosinophil infiltration and activation in the lungs. TREATMENT Eosinophilia Definitive treatment is directed at the underlying malignancy. Tumors should be resected or treated with radiation or chemo­ therapy. In most patients who develop shortness of breath related to eosinophilia, symptoms resolve with the use of oral or inhaled glucocorticoids. IL-5 antagonists exist but have not been evaluated in this clinical setting. CHAPTER 98 ■ ■THROMBOPHLEBITIS AND DEEP VENOUS THROMBOSIS Deep venous thrombosis and pulmonary embolism are the most common thrombotic conditions in patients with cancer. Migratory or recurrent thrombophlebitis may be the initial manifestation of cancer. Nearly 15% of patients who develop deep venous thrombosis or pulmonary embolism have a diagnosis of cancer (Chap. 122). The coexistence of peripheral venous thrombosis with visceral carcinoma, particularly pancreatic cancer, is called Trousseau’s syndrome. Paraneoplastic Syndromes: Endocrinologic/Hematologic Pathogenesis  Patients with cancer are predisposed to thromboem­ bolism because they are often at bed rest or immobilized, and tumors may obstruct or slow blood flow. Postoperative deep venous throm­ bosis is twice as common in cancer patients who undergo surgery. Chronic IV catheters also predispose to clotting. In addition, clotting may be promoted by release of procoagulants or cytokines from tumor cells or associated inflammatory cells or by platelet adhesion or aggre­ gation. The specific molecules that promote thromboembolism have not been identified. Chemotherapeutic agents, particularly those associated with endo­ thelial damage, can induce venous thrombosis. The annual risk of venous thrombosis in patients with cancer receiving chemotherapy is about 11%, sixfold higher than the risk in the general population. Bleomycin, l-asparaginase, nitrogen mustard, thalidomide analogues, cisplatin-based regimens, and high doses of busulfan and carmustine are all associated with an increased risk. In addition to cancer and its treatment causing secondary thrombo­ sis, primary thrombophilic diseases may be associated with cancer. For example, the antiphospholipid antibody syndrome is associated with a wide range of pathologic manifestations (Chap. 369). About 20% of patients with this syndrome have cancers. Among patients with cancer and antiphospholipid antibodies, 35–45% develop thrombosis. Clinical Manifestations  Patients with cancer who develop deep venous thrombosis usually develop swelling or pain in the leg, and physical examination reveals tenderness, warmth, and redness. Patients who present with pulmonary embolism develop dyspnea, chest pain, and syncope, and physical examination shows tachycardia, cyanosis, and hypotension. Some 5% of patients with no history of cancer who have a diagnosis of deep venous thrombosis or pulmonary embolism will have a diagnosis of cancer within 1 year. The most common cancers associated with thromboembolic episodes include lung, pan­ creatic, gastrointestinal, breast, ovarian, and genitourinary cancers; lymphomas; and brain tumors. Patients with cancer who undergo surgical procedures requiring general anesthesia have a 20–30% risk of deep venous thrombosis. Diagnosis  The diagnosis of deep venous thrombosis in patients with cancer is made by impedance plethysmography or bilateral compression ultrasonography of the leg veins. Patients with a noncom­ pressible venous segment have deep venous thrombosis. If compres­ sion ultrasonography is normal and there is a high clinical suspicion for deep venous thrombosis, venography should be done to look for a luminal filling defect. Elevation of d-dimer is not as predictive of deep venous thrombosis in patients with cancer as it is in patients without cancer; elevations are seen in people over age 65 years without concom­ itant evidence of thrombosis, probably as a consequence of increased thrombin deposition and turnover in aging. Patients with symptoms and signs suggesting a pulmonary embo­ lism should be evaluated with a chest radiograph, electrocardiogram, arterial blood gas analysis, and ventilation-perfusion scan. Patients with mismatched segmental perfusion defects have a pulmonary embolus. Patients with equivocal ventilation-perfusion findings should be evaluated as described above for deep venous thrombosis in their legs. If deep venous thrombosis is detected, they should be antico­ agulated. If deep venous thrombosis is not detected, they should be considered for a pulmonary angiogram. Patients without a diagnosis of cancer who present with an initial episode of thrombophlebitis or pulmonary embolus need no additional tests for cancer other than a careful history and physical examination. In light of the many possible primary sites, diagnostic testing in asymp­ tomatic patients is wasteful. However, if the clot is refractory to standard treatment or is in an unusual site, or if the thrombophlebitis is migra­ tory or recurrent, efforts to find an underlying cancer are indicated. PART 4 Oncology and Hematology TREATMENT Thrombophlebitis and Deep Venous Thrombosis Patients with cancer and a diagnosis of deep venous thrombosis or pulmonary embolism should be treated initially with IV unfraction­ ated heparin or low-molecular-weight heparin for at least 5 days, and warfarin should be started within 1 or 2 days. The warfarin dose should be adjusted so that the international normalized ratio (INR) is 2–3. Patients with proximal deep venous thrombosis and a relative contraindication to heparin anticoagulation (hemorrhagic brain metastases or pericardial effusion) should be considered for placement of a filter in the inferior vena cava (Greenfield filter) to prevent pulmonary embolism. Warfarin should be administered for 3–6 months. An alternative approach is to use low-molecularweight heparin for 6 months. The new oral anticoagulants (factor Xa and thrombin inhibitors) are attractive because they do not require close monitoring of the prothrombin time and are not affected by dietary factors. Oral apixaban (10 mg bid for 7 days fol­ lowed by 5 mg bid for 6 months) is noninferior to dalteparin in the treatment of cancer patients who develop deep vein thrombosis or pulmonary embolism. Patients with cancer who undergo a major surgical procedure should be considered for heparin prophylaxis or pneumatic boots. Breast cancer patients undergoing chemotherapy and patients with implanted catheters should be considered for prophylaxis. Guidelines recommend that hospitalized patients with cancer and patients receiving a thalidomide analogue receive pro­ phylaxis with low-molecular-weight heparin or low-dose aspirin. Use of prophylaxis routinely during chemotherapy is controversial. Risk is affected by type of cancer, type of therapy, blood counts, and body mass index (all taken into account in the Khorana risk score; Table 98-3). Studies of Khorana high-risk patients with cancer using rivaroxaban and apixaban as clot prophylaxis have resulted in a 50% reduction in risk with a level of bleeding of about 5%. How­ ever, prophylaxis is not routinely recommended by the American Society of Clinical Oncology. TABLE 98-3  Khorana Risk Score for Venous Thromboembolism in Cancer Patients PATIENT CHARACTERISTICS RISK SCORE POINTS Site of cancer   Very high risk (stomach, pancreas)   High risk (lung, lymphoma, gynecologic, genitourinary excluding prostate) Prechemotherapy platelet count ≥350,000/μL Hemoglobin level <10 g/dL or use of red cell growth factors Prechemotherapy leukocyte count >11,000/μL BMI ≥35 kg/m2 RATES OF sVTE ACCORDING TO SCORES (%) RISK SCORE (POINTS) RISK CATEGORY Low 0.3–0.8 1–2 Intermediate 1.8–2.0 ≥3 High 6.7–7.1 Abbreviations: BMI, body mass index; sVTE, symptomatic venous thromboembolism. Source: Reproduced from AJM Muñoz et al: Clinical guide SEOM on venous thromboembolism in cancer patients. Clin Transl Oncol 16:1079-1090, 2014. MISCELLANEOUS REMOTE EFFECTS OF CANCER Patients with cancer can develop paraneoplastic autoimmune disor­ ders (e.g., thrombocytopenia) and dysfunction of organs not directly invaded or involved with the cancer (rheumatologic and renal abnor­ malities are among the most frequent). The pathogenesis of these disorders is undefined, but often, the conditions reverse if the tumor is removed or successfully treated. Cutaneous paraneoplastic syndromes are discussed in Chap. 61. Neurologic paraneoplastic syndromes are discussed in Chap. 99. ■ ■FURTHER READING Agnelli G et al: Apixaban for the treatment of venous thromboembo­ lism associated with cancer. N Engl J Med 382:1599, 2020. Asonitis N et al: Diagnosis, pathophysiology and management of hypercalcemia in malignancy: A review of the literature. Horm Metab Res 51:770, 2019. Catani MV et al: The “Janus face” of platelets in cancer. Int J Mol Sci 21:788, 2020. Dynkevich Y et al: Tumors, IGF-2, and hypoglycemia: Insights from the clinic, the laboratory, and the historical archive. Endocr Rev 34:798, 2013. Feelders RA et al: Advances in the medical treatment of Cushing’s syndrome. Lancet Diabetes Endocrinol 7:300, 2019. Farge D et al: 2022 international clinical practice guidelines for the treatment and prophylaxis of thromboembolism in patients with cancer, including COVID19. Lancet Oncol 23:e334, 2022. Hattersley R et al: Endocrine complications of immunotherapies: A review. Clin Med 21:e212, 2021. Jan de Beur SM et al: Burosumab for the treatment of tumor-induced osteomalacia. J Bone Miner Res 36:627, 2021. Lin RJ et al: Paraneoplastic thrombocytosis: The secrets of tumor selfpromotion. Blood 124:184, 2014. Onyema MC et al: Endocrine abnormality in paraneoplas­ tic syndrome. Best Pract Res Clin Endocrinol Metab 36:101621, 2022. Pelosof LC, Gerber DE: Paraneoplastic syndromes: An approach to diagnosis and treatment. Mayo Clin Proc 85:838, 2010. Workeneh BT et al: Hyponatremia in the cancer patient. Kidney Int 98:870, 2020. # 28 - 99 Paraneoplastic Neurologic Syndromes and Autoimmune Encephalitis ### 99 Paraneoplastic Neurologic Syndromes and Autoimmune Encephalitis Josep Dalmau, Francesc Graus Paraneoplastic Neurologic Syndromes and Autoimmune Encephalitis Paraneoplastic neurologic disorders (PNDs) are cancer-related syn­ dromes that can affect any part of the nervous system (Table 99-1). Initially defined as syndromes of unknown cause, currently most PNDs are considered to have an autoimmune pathogenesis triggered by the underlying cancer. In 60% of patients, the neurologic symptoms pre­ cede the cancer diagnosis. Clinically disabling PNDs occur in 0.5–1% of all cancer patients, but they affect 2–3% of patients with neuroblas­ toma or small-cell lung cancer (SCLC) and 30–50% of patients with thymoma. PATHOGENESIS Most PNDs are mediated by immune responses triggered by neuro­ nal proteins ectopically expressed by tumors (e.g., SCLC and other cancers) or as a result of altered immunologic responses caused by some types of tumors such as thymomas or lymphomas. In PNDs of the central nervous system (CNS), many antibody-associated immune responses have been identified. These antibodies react with neurons and the patient’s tumor, and their detection in serum or cerebrospinal fluid (CSF) variably predicts the presence of cancer. According to the frequency of an underlying tumor, these antibodies are classified as high risk (>70% probability of an underlying tumor; Table 99-2); inter­ mediate risk (30–70% probability of an underlying tumor; Table 99-3), and low risk (<30% probability of an underlying tumor; Table 99-4). All the target antigens of high-risk antibodies are intracellular proteins except for Tr (DNER [delta/notch-like epidermal growth factor-related receptor]), which is expressed on the cell surface. By contrast, all target antigens of intermediate- and low-risk antibodies are cell-surface pro­ teins or receptors except for GAD65 and glial fibrillary acidic protein (GFAP), which are intracellular. When the antigens are intracellular, most neurologic syndromes are associated with extensive infiltrates of CD4+ and CD8+ T cells, microglial activation, gliosis, and variable neuronal loss. The infiltrating T cells are often in close contact with neurons undergoing degeneration, suggesting a primary pathogenic role. T-cell–mediated cytotoxicity may contribute directly to cell death TABLE 99-1  Paraneoplastic Syndromes of the Nervous System CLASSIC SYNDROMES: HIGH RISK OF ASSOCIATED CANCERa NONCLASSIC SYNDROMES: MODERATE OR LOW RISK OF ASSOCIATED CANCER Encephalomyelitis Limbic encephalitis Cerebellar degeneration (adults) Opsoclonus-myoclonus Sensory neuronopathy Gastrointestinal pseudoobstruction (enteric neuropathy) Dermatomyositis (adults) Lambert-Eaton myasthenic syndrome Cancer- or melanoma-associated retinopathy Brainstem encephalitis Stiff-person syndrome Progressive encephalomyelitis with rigidity and myoclonus Necrotizing myelopathy Motor neuron disease Subacute axonal sensory-motor neuropathies Paraproteinemic neuropathies Pure autonomic neuropathy Acute necrotizing myopathy Polymyositis Optic neuropathy BDUMP Peripheral nerve hyperexcitability (neuromyotonia) Myasthenia gravis aThese syndromes frequently associate with cancer. Abbreviation: BDUMP, bilateral diffuse uveal melanocytic proliferation. TABLE 99-2  High-Risk Antibodies (>70% Probability of an Underlying Cancer), Syndromes, and Associated Tumors ANTIBODYa ASSOCIATED NEUROLOGIC SYNDROME(S) TUMORS Anti-Hu (ANNA1) Encephalomyelitis, sensory neuronopathy SCLC Anti-Yo (PCA1) Rapidly progressive cerebellar syndrome Ovary, breast Anti-Ri (ANNA2) Cerebellar degeneration, opsoclonus, brainstem encephalitis Breast, gynecologic, SCLC Anti-CRMP5 (CV2) Encephalomyelitis, chorea, optic neuritis, uveitis, peripheral neuropathy SCLC, thymoma, other Anti-Tr (DNER) Rapidly progressive cerebellar syndrome Hodgkin’s lymphoma Anti-Ma proteins Limbic, hypothalamic, brainstem encephalitis Testicular (Ma2), other (Ma) Anti-PCA2 (MAP1B) Sensorimotor neuropathy, rapidly SCLC, non-SCLC, breast cancer progressive cerebellar syndrome, and encephalomyelitis Anti-Kelch-like protein 11 Brainstem encephalitis, ataxia, sensorineural hearing loss Seminoma, germ cell tumor, teratoma, CHAPTER 99 Anti-amphiphysinb Stiff-person syndrome, encephalomyelitis Breast, SCLC Anti-SOX1 LEMS, rapidly progressive cerebellar syndrome with and without LEMS SCLC Paraneoplastic Neurologic Syndromes and Autoimmune Encephalitis aAll the antibodies of this table are against intracellular antigens, except for Tr (DNER), which is a cell-surface protein. bAmphiphysin is likely exposed to the cell surface during synaptic vesicle endocytosis. Abbreviations: CRMP, collapsin response-mediator protein; DNER, delta/notch-like epidermal growth factor-related receptor; LEMS, Lambert-Eaton myasthenic syndrome; MAP1B, microtubule associated protein 1B; PCA, Purkinje cell antigen; SCLC, small-cell lung cancer. in these PNDs and probably underlies the resistance of many of these conditions to therapy. In contrast to the predominant role of cytotoxic T-cell mechanisms in PNDs associated with antibodies against intracellular antigens, those asso­ ciated with antibodies to antigens expressed on the neuronal cell surface of the CNS or at the neuromuscular junction are mediated by direct antibody effects on the target antigens and are more responsive to immunotherapy (Tables 99-3 and 99-4, Fig. 99-1). These disorders occur with and without a cancer association and may affect children and young adults. Some disorders are triggered by viral encephalitis such as herpes simplex virus encephalitis or Japanese encephalitis leading to autoimmune encephalitis. TABLE 99-3  Intermediate-Risk Antibodies (30–70% Probability of an Underlying Cancer), Syndromes, and Associated Tumors TUMOR TYPE WHEN ASSOCIATED ANTIBODYa NEUROLOGIC SYNDROME Anti-NMDARb Anti-NMDAR encephalitis Teratoma in young women (children and men rarely have tumors) Anti-AMPARb Limbic encephalitis with relapses SCLC, thymoma, breast Anti-GABABRc Limbic encephalitis with early and prominent seizures SCLC Anti-Caspr2b Morvan syndrome Thymoma Anti-mGluR5b Autoimmune encephalitis without distinctive features Hodgkin lymphoma Anti-VGCCb LEMS, cerebellar degeneration SCLC aAll the antibodies of this table are against neuronal cell-surface proteins. bA direct pathogenic role of these antibodies has been demonstrated in cultured neurons or animal models. cThese antibodies are strongly suspected to be pathogenic. Abbreviations: AMPAR, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor; Caspr2, contactin-associated protein-like 2; GABABR, γ-aminobutyric acid B receptor; LEMS, Lambert-Eaton myasthenic syndrome; mGluR, metabotropic glutamate receptor; NMDAR, N-methyl-d-aspartate receptor; SCLC, small-cell lung cancer; VGCC, voltage-gated calcium channel. TABLE 99-4  Low-Risk Antibodies (<30% Probability of an Underlying Cancer), Syndromes, and Associated Tumors TUMOR TYPE WHEN ASSOCIATED ANTIBODYa NEUROLOGIC SYNDROME Anti-LGI1b Limbic encephalitis, hyponatremia, faciobrachial dystonic seizures Rarely thymoma Anti-GABAARb Encephalitis with prominent seizures and status epilepticus Thymoma in ~20% of the patients Anti-DPPXb Agitation, myoclonus, tremor, seizures, hyperekplexia, encephalomyelitis with rigidity No cancer, but frequent diarrhea or cachexia suggesting paraneoplasia Anti-glycine receptorb PERM, stiff-person syndrome Rarely, thymoma, lung, Hodgkin’s lymphoma Anti-IgLON5b NREM and REM sleep disorder, brainstem dysfunction, movement disorder, obstructive sleep apnea, stridor No tumor association Anti-GAD65 Stiff-person, cerebellar syndrome, encephalitis with seizures, limbic encephalitis Infrequent tumor association (thymoma, lung, and breast cancer) Anti-mGluR1b Cerebellar syndrome Hodgkin’s lymphoma in <10% of patients PART 4 Oncology and Hematology Anti-GFAP Meningoencephalitis and myelitis No cancer association Anti-aquaporin 4b Neuromyelitis optica spectrum Lung and breast adenocarcinomas in a few patients disorders Anti-MOG ADEM, optic neuritis, myelitis, cortical encephalitis No cancer association Anti-AChR (muscle)b Myasthenia gravis Thymoma Anti-AChR (neuronal)b Autonomic ganglionopathy SCLC aAll the antibodies of this table are against cell-surface proteins except for GAD65 and GFAP which are intracellular proteins. Rare antibodies reported in <30 patients are not included. bA direct pathogenic role of these antibodies has been demonstrated in cultured neurons or animal models. Abbreviations: AChR, acetylcholine receptor; ADEM, acute disseminated encephalomyelitis; DPPX, dipeptidyl-peptidase-like protein-6; GABAAR, γ-aminobutyric acid A receptor; GAD, glutamic acid decarboxylase; GFAP, glial fibrillary acidic protein; LGI1, leucine-rich glioma-inactivated 1; mGluR, metabotropic glutamate receptor; MOG, myelin oligodendrocyte glycoprotein; NREM, non–rapid eye movement; PERM, progressive encephalomyelitis with rigidity and myoclonus; REM, rapid eye movement; SCLC, small-cell lung cancer. In patients with cancer, the use of immune checkpoint inhibitors is associated in <3% of cases with neurologic immune-related adverse events that may be accompanied by neuronal antibodies, in which case the associated syndromes are indistinguishable from PNDs. Other PNDs are likely immune-mediated, although their antigens are unknown. The best example is opsoclonus-myoclonus syndrome associated with neuroblastoma or SCLC. For still other PNDs, the cause remains quite obscure. These include, among others, several neuropathies that occur in the terminal stages of cancer and a number of neuropathies associated with plasma cell dyscrasias or lymphoma without evidence of tumor infiltration or deposits of immunoglobulin, cryoglobulin, or amyloid. APPROACH TO THE PATIENT Paraneoplastic Neurologic Disorders Three key concepts are important for the diagnosis and manage­ ment of PNDs. First, it is common for symptoms to appear before the presence of a tumor is known; second, the neurologic syndrome usually develops rapidly, producing severe deficits in a short period of time; and third, there is evidence that prompt tumor control improves the neurologic outcome. Therefore, the major concern of the physician is to recognize a disorder as paraneoplastic as early as possible and to identify and treat the tumor. PND OF THE CENTRAL NERVOUS SYSTEM AND DORSAL ROOT GANGLIA When symptoms involve brain, spinal cord, or dorsal root ganglia, the suspicion of PND is usually based on a combination of clinical, radiologic, and CSF findings. Presence of antineuronal antibodies (Tables 99-2, 99-3, and 99-4) may help in the diagnosis, but only 60–70% of PNDs of the CNS and <20% of those involving the peripheral nervous system have neuronal or neuromuscular junc­ tion antibodies that can be used as diagnostic tests. Magnetic resonance imaging (MRI) and CSF studies are impor­ tant to rule out neurologic complications due to the direct spread of cancer, particularly metastatic and leptomeningeal disease. In most PNDs, the MRI findings are nonspecific. Paraneoplastic limbic encephalitis is usually associated with characteristic MRI abnormalities in the mesial temporal lobes (see below), but similar findings can occur with other disorders (e.g., nonparaneoplastic autoimmune limbic encephalitis and human herpesvirus type 6 [HHV-6] encephalitis) (Fig. 99-2A). The CSF profile of patients with PND of the CNS or dorsal root ganglia typically consists of mild to moderate pleocytosis (<200 mononuclear cells, predomi­ nantly lymphocytes), an increase in the protein concentration, and a variable presence of oligoclonal bands. There are no specific electrophysiologic tests that are diagnostic of PND of the CNS. Moreover, a biopsy of the affected tissue is often difficult to obtain, and although useful to rule out other disorders (e.g., metastasis), the pathologic findings are not specific for PND. PND OF NERVE AND MUSCLE If symptoms involve peripheral nerve, neuromuscular junction, or muscle, the diagnosis of a specific PND is usually established on clinical, electrophysiologic, and pathologic grounds. The clinical history, accompanying symptoms (e.g., anorexia, weight loss), and type of syndrome dictate the studies and degree of effort needed to demonstrate a neoplasm. For example, the frequent association of Lambert-Eaton myasthenic syndrome (LEMS) with SCLC should lead to a chest and abdomen computed tomography (CT) or body positron emission tomography (PET) scan and, if negative, periodic tumor screening for at least 3 years after the neurologic diagnosis. In contrast, the weak association of polymyositis with cancer calls into question the need for repeated cancer screenings in this situation. Serum and urine immunofixation studies should be considered in patients with peripheral neuropathy of unknown cause; detection of a monoclonal gammopathy suggests the need for additional studies to uncover a B-cell or plasma-cell malignancy. In paraneoplastic neuropathies, diagnostically useful neuronal antibodies are limited to CRMP5 (CV2) and Hu (ANNA1). For any type of PND, if neuronal antibodies are negative, the diagnosis relies on the demonstration of cancer and the exclusion of other cancer-related or independent neurologic disorders. Com­ bined CT and PET scans often uncover tumors undetected by other tests. For germ cell tumors of the testis and teratomas of the ovary, ultrasound (testicular, transvaginal, or pelvic) and MRI or CT of the abdomen and pelvis may reveal tumors undetectable by PET. SPECIFIC PARANEOPLASTIC NEUROLOGIC SYNDROMES ■ ■PARANEOPLASTIC ENCEPHALOMYELITIS AND FOCAL ENCEPHALITIS WITH HIGH-RISK ANTIBODIES FOR AN UNDERLYING CANCER The term encephalomyelitis describes an inflammatory process with multifocal involvement of the nervous system, including brain, brain­ stem, cerebellum, and spinal cord. It is often associated with dorsal root ganglia and autonomic dysfunction. For any given patient, the clinical A B C D E F G H I J FIGURE 99-1  Antibody reactivity and pathologic findings in patients with antibodies against intracellular antigens compared with those of patients with antibodies against neuronal surface antigens. In encephalitis associated with antibodies against intracellular antigens, the antibodies cannot reach the intracellular epitopes and cytotoxic T-cell mechanisms are predominantly involved (A), whereas in encephalitis with antibodies against surface antigens, the antibodies have access to the epitopes and can potentially alter the structure and function of the antigen (B). The Hu antibodies (C, E) are shown here to exemplify the group of antibodies against intracellular antigens, and the NMDAR antibodies (D, F) are shown to exemplify the group of antibodies against cell-surface antigens. In rodent brain immunofluorescence with tissue permeabilized to allow entry of antibodies, the Hu antibodies produce a discrete pattern of cellular immunolabeling (C), whereas the NMDAR antibodies produce a pattern of neuropil-like immunolabeling (D). In contrast, with live cultured neurons, only the NMDAR antibodies have access to the target antigen showing intense immunolabeling (F), whereas the Hu antibodies cannot reach the intracellular antigen showing no immunolabeling (E). In autopsy studies, patients with encephalitis associated with antibodies to intracellular antigens (Hu or other) have extensive neuronal loss and inflammatory infiltrates (not shown); the T cells show direct contact with neurons (arrows in G) likely contributing to neuronal degeneration via perforin and granzyme mechanisms (arrow in H). In contrast, patients with antibodies against cell-surface antigens (NMDAR shown here, and probably applicable to other antigens) have moderate brain inflammatory infiltrates along with plasma cells (brown cells in I), deposits of IgG (diffuse brown staining in J), and microglial proliferation (inset in J), without evidence of predominant T-cell–mediated neuronal loss (not shown). All human tissue sections (G-J) were obtained from hippocampus. (From J Dalmau: Antibody mediated encephalitis. N Engl J Med 378:840, 2018. Copyright © 2018 Massachusetts Medical Society. Reprinted with permission.) CHAPTER 99 Paraneoplastic Neurologic Syndromes and Autoimmune Encephalitis A B PART 4 Oncology and Hematology C D FIGURE 99-2  Brain MRI findings in paraneoplastic and autoimmune encephalitis. Representative MRI studies of patients with several types of autoimmune encephalitides. A. Limbic encephalitis (LE) may result from several different immune responses (Hu, Ma2, AMPAR, GABABR, LGI1, Caspr2) and typically manifests with unilateral or bilateral medial temporal lobe increased FLAIR signal. B. AntiNMDAR encephalitis often occurs with normal MRI findings or mild FLAIR signal abnormalities. C. In contrast, anti-GABAAR encephalitis usually occurs with multiple cortical-subcortical increased FLAIR signal changes. D. Cortical encephalitis can occur in patients with myelin oligodendrocyte glycoprotein (MOG) antibodies, as shown in this T2-weighted MRI image from a 3-year-old boy who presented with extensive cortical abnormalities with mild enhancement (not shown here) suggesting cortical necrosis. (Panels A-C from J Dalmau: Antibody mediated encephalitis. N Engl J Med 378:840, 2018. Copyright © 2018 Massachusetts Medical Society. Reprinted with permission. Panel D from T Armangue: Associations of paediatric demyelinating and encephalitic syndromes with myelin oligodendrocyte glycoprotein antibodies: A multicentre observational study. Lancet Neurol 19:234, 2020.) manifestations are determined by the areas predominantly involved, but pathologic studies almost always reveal abnormalities beyond the symptomatic regions. Several clinicopathologic syndromes may occur alone or in combination: (1) cortical encephalitis, which may present as “epilepsia partialis continua”; (2) limbic encephalitis, characterized by confusion, depression, agitation, anxiety, severe deficit forming new memories (“short-term memory deficit”), and temporal lobe or gen­ eralized seizures (the MRI usually shows unilateral or bilateral medial temporal lobe abnormalities, best seen with T2 and fluid-attenuated inversion recovery [FLAIR] sequences); (3) brainstem encephalitis, resulting in eye movement disorders (nystagmus, opsoclonus, supra­ nuclear or nuclear paresis), cranial nerve paresis, dysarthria, dysphagia, unsteady gait, and central autonomic dysfunction; (4) cerebellar gait and limb ataxia; (5) myelitis, which may cause lower or upper motor neuron symptoms, myoclonus, muscle rigidity, spasms, fasciculations, sensory deficits, and sphincter dysfunction; and (6) autonomic dys­ function as a result of involvement of the neuraxis at multiple levels, including hypothalamus, brainstem, and autonomic nerves (see “Paraneoplastic Peripheral Neuropathies,” below). Cardiac arrhythmias, postural hypotension, and central hypoventilation can be the cause of death in patients with encephalomyelitis. Paraneoplastic encephalomyelitis and focal encephalitis are usually associated with SCLC, but many other cancers have been implicated. Patients with SCLC and these syndromes usually have Hu antibodies in serum and CSF. CRMP5 antibodies occur less frequently; some of these patients may develop chorea, uveitis, or optic neuritis. Antibodies to Ma proteins are associated with limbic, hypothalamic, and brainstem encephalitis and occasionally with cerebellar symptoms; some patients develop hypersomnia, cataplexy, and severe hypokinesia. MRI abnor­ malities are frequent, including those described with limbic encepha­ litis and variable involvement of the hypothalamus, basal ganglia, or upper brainstem. Kelch-like protein 11 antibodies are predominantly associated with brainstem encephalitis, vertigo, sensorineural hearing loss, and seminomas, germ cell tumors, and teratomas. Amphiphysin antibodies usually are associated with paraneoplastic stiff-person syndrome, but in some patients, they can occur with paraneoplastic encephalomyelitis or isolated myelitis. The oncologic associations of these antibodies are shown in Table 99-2. Most types of paraneoplastic encephalitis and encephalomyelitis in which the antigens are intracellular respond poorly to treatment. Sta­ bilization of symptoms or partial neurologic improvement may occur, particularly if there is a satisfactory response of the tumor to treatment. Controlled trials of therapy are lacking, but many reports and the opin­ ion of experts suggest that therapies aimed to remove the antibodies against intracellular antigens, such as intravenous immunoglobulin (IVIg) or plasma exchange, usually fail. The main concern should be to treat the tumor and consider immunotherapies aimed at cytotoxic T-cell responses. Approximately 30% of patients with anti-Ma2-associ­ ated encephalitis respond to treatment of the tumor (usually a germ cell neoplasm of the testis) and immunotherapy. Cortical encephalitis can occur with antibodies against myelin oligodendrocyte glycoprotein (MOG) (Chap. 456), and encephalomy­ elitis can occur with antibodies against GFAP (Chap. 456). These two disorders rarely associate with cancer and respond better to immu­ notherapy than the indicated paraneoplastic syndromes. Encephalitis with seizures, limbic encephalitis, stiff-person syndrome, or cerebellar ataxia can occur with GAD65 antibodies; this type of autoimmunity rarely associates with cancer but responds less frequently to immu­ notherapy than similar syndromes associated with antibodies against neuronal surface proteins. ■ ■ENCEPHALITIDES WITH INTERMEDIATE- OR LOW-RISK ANTIBODIES FOR AN UNDERLYING CANCER These disorders are important for four reasons: (1) they can occur with and without tumor association; less frequently, they develop after a viral encephalitis (herpes simplex or Japanese encephalitis); (2) some syndromes predominate in young individuals and children; (3) despite the severity of the symptoms, patients usually respond to treatment of the tumor, if found, and immunotherapy (e.g., glucocorticoids, IVIg, plasma exchange, rituximab, or cyclophosphamide); and (4) for many of these disorders, the antibody pathogenicity has been demonstrated in models using cultures of neurons or passive transfer of patients’ antibodies to animals (Fig. 99-3). Encephalitis with N-methyl-d-aspartate receptor (NMDAR) antibod­ ies usually occurs in young women and children, but men and older patients of both sexes can be affected. The disorder has a character­ istic pattern of symptom progression that often includes a prodrome resembling a viral process, followed in a few days by the onset of severe psychiatric symptoms, sleep dysfunction (usually insomnia), reduced verbal output, memory loss, seizures, decreased level of consciousness, abnormal movements (orofacial, limb, and trunk dyskinesias, dystonic postures), autonomic instability, and frequent hypoventilation. Mono­ symptomatic episodes, such as pure psychosis, occur in about 5% of patients. Clinical relapses occur in 12–24% of patients (12% during the first 2 years after initial presentation). Most patients have intrathe­ cal synthesis of antibodies, likely by infiltrating plasma cells in brain and meninges (Fig. 99-1I). In about 65% of patients, the brain MRI is normal; in the other 35%, it shows FLAIR abnormalities that can affect cortical and subcortical regions, usually mild and transient, and rarely A B D E F FIGURE 99-3  Proposed mechanisms of disease and functional interactions of autoantibodies with neuronal surface proteins. The graph shows a multistep process that results in antibody-mediated neuronal dysfunction; some of the steps have been demonstrated in reported studies, whereas others are based on proposed hypotheses. Two well-known triggers of autoimmune encephalitides are represented: herpes simplex encephalitis (A) and systemic tumors (B); the genetic susceptibility of some autoimmune encephalitides and unknown immunologic triggers are not depicted. It is postulated that antigens released by viral-induced neuronal destruction or apoptotic tumor cells are loaded into antigen-presenting cells (APCs; dendritic cells) and transported to regional lymph nodes. In the lymph nodes, naïve B cells exposed to the processed antigens, with cooperation of CD4+ T cells, become antigen-experienced and differentiate into antibody-producing plasma cells. After entering the brain, memory B cells undergo restimulation, antigen-driven affinity maturation, clonal expansion, and differentiation into antibody-producing plasma cells (C). The contribution of systemically produced antibodies to the pool of antibodies present in the brain is unclear and may depend on systemic antibody titers and integrity of the blood-brain barrier. Based on experimental models with cultured neurons, the presence of antibodies in the brain may lead to neuronal dysfunction by different mechanisms, including functional blocking of the target antigen (GABABR antibodies; D), receptor crosslinking and internalization (NMDAR antibodies; E), and disruption of protein-protein interaction, leading to downstream effects on receptors (LGI1 leading to a decrease of Kv1 potassium channels and AMPAR; F). These mechanisms are influenced by the type of antibodies; for example, whereas IgG1 antibodies frequently crosslink and internalize the target antigen, IgG4 antibodies are less effective at crosslinking the target and more often alter protein-protein interactions. (Panels D-F from J Dalmau: Antibody mediated encephalitis. N Engl J Med 378:840, 2018. Copyright © 2018 Massachusetts Medical Society. Reprinted with permission.) the presence of contrast enhancement (Fig. 99-2B). The syndrome may be misdiagnosed as a viral or idiopathic encephalitis, neuroleptic malignant syndrome, or encephalitis lethargica, and some patients are initially evaluated by psychiatrists with the suspicion of acute psychosis as the presentation of a primary psychiatric disease. The detection of an associated teratoma is dependent on age and gender: 46% of female patients 12 years or older have uni- or bilateral ovarian teratomas, whereas <7% of girls younger than 12 have a teratoma (Fig. 99-4A). In young male patients, the detection of a tumor is rare. Patients older than 45 years are more frequently male; about 20% of these patients have tumors (e.g., cancer of the breast, ovary, or lung). Prompt diag­ nosis and treatment with immunotherapy (and tumor removal when it applies) improve outcome. Treatment usually includes first-line immunotherapy (steroids, IVIg, or plasma exchange), and if there is no response, second-line immunotherapy (rituximab and cyclophospha­ mide). Rituximab is highly effective and is increasingly used as part of first-line treatments. The response to treatment can take several weeks, and the improvement is usually slow. Overall, about 85–90% of patients have substantial neurologic improvement or full recovery. Deficits of C CHAPTER 99 Paraneoplastic Neurologic Syndromes and Autoimmune Encephalitis attention, memory, and executive functions may recover slowly over many months. During the process of recovery, patients often develop transient hypersomnia and, less frequently, hyperphagia, hypersexual­ ity, apathy, and irritability, resembling a Kleine-Levin syndrome. Approximately 25% of patients with herpes simplex encephalitis develop a form of autoimmune encephalitis that usually is associ­ ated with abnormal movements (choreoathetosis after herpes simplex encephalitis) in children and with cognitive and psychiatric symptoms in adults. This disorder develops a few weeks after the viral infection has resolved, is associated with new synthesis of antibodies against the NMDAR and other neuronal cell surface proteins, and is usually less responsive to immunotherapy than anti-NMDAR encephalitis (idio­ pathic or teratoma-associated). Encephalitis with α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor antibodies affects middle-aged women, who develop acute limbic dysfunction or, less frequently, prominent psychi­ atric symptoms; 70% of patients have an underlying tumor in the lung, breast, or thymus (Fig. 99-4B). In about 50% of cases, the brain MRI shows typical features of limbic encephalitis (similar to Fig. 99-2A). A B FIGURE 99-4  Immunopathological studies in tumors of patients with autoimmune encephalitis. A. Neurons and neuronal processes (brown cells; stained with MAP2) in the teratoma of a patient with anti-NMDA receptor encephalitis; these neurons express NMDAR (not shown). B. Lung cancer from a patient with anti–α-amino-3-hydroxy5-methyl-4-isoxazolepropionic acid (AMPA) receptor encephalitis showing expression of AMPA receptors by the neoplastic cells (brown cells). (Panel B from M Lai et al: AMPA receptor antibodies in limbic encephalitis alter synaptic receptor location. Ann Neurol 65:424, 2009.) PART 4 Oncology and Hematology Neurologic relapses may occur; these also respond to immunotherapy and are not necessarily associated with tumor recurrence. Encephalitis with GluK2 antibodies can affect children and adults and is associated with rapidly progressive encephalopathy with cer­ ebellar ataxia or cerebellitis. Symptoms of encephalopathy may include impairment of memory and level of consciousness and motor altera­ tions such as dyskinesias, choreoathetosis, bradykinesia, and spastic paraparesis. Some patients develop intracranial hypertension. In one patient, the symptoms were associated with teratoma. Encephalitis with γ-aminobutyric acid type A (GABAA) receptor anti­ bodies may affect children and adults and is associated with prominent seizures and status epilepticus often requiring a pharmacologically induced coma. In approximately 80% of patients, the brain MRI shows multifocal, asynchronous, cortical-subcortical T2/FLAIR abnormali­ ties predominantly involving temporal and frontal lobes, but also basal ganglia and other regions (Fig. 99-2C). Most patients do not have an underlying tumor, but some may have thymoma. Encephalitis with GABAB receptor antibodies is usually associated with limbic encephalitis and seizures. In >50% of cases, the MRI shows increased medial temporal lobe FLAIR changes characteristic of limbic encephalitis (similar to Fig. 99-2A). In rare instances, patients develop cerebellar symptoms and opsoclonus. Fifty percent of patients have SCLC or a neuroendocrine tumor of the lung. The outcome is substan­ tially better in patients without cancer. Encephalitis with glycine receptor (GlyR) antibodies usually manifests with a syndrome characterized by progressive encephalomyelitis with rigidity and myoclonus (PERM) or stiff-person spectrum of symptoms. The disease usually occurs in adults and rarely in children. About 20% of adult patients have a concurrent underlying tumor (thymoma, B-cell lymphoma, or breast or lung cancer) or past history of cancer (thymoma, breast cancer, Hodgkin’s lymphoma, or melanoma). Encephalitis with metabotropic glutamate receptor 5 (mGluR5) anti­ bodies is characterized by nonspecific clinical features of encephalitis (confusion, agitation, memory loss, delusions, paranoid ideation, hallucinations, psychosis, or seizures) without distinctive MRI changes and frequent association with Hodgkin’s lymphoma. The encephalitis is highly responsive to immunotherapy and treatment of the tumor. Encephalitis with antibodies against dopamine-2 receptor has been reported in children with basal ganglia encephalitis manifesting with abnormal movements (coarse tremor, parkinsonism, chorea, ocu­ logyric crises) along with psychiatric features, lethargy, drowsiness, brainstem dysfunction, or ataxia. The disorder is extremely rare and is not associated with cancer. Encephalitis with leucine-rich glioma-inactivated 1 (LGI1) antibod­ ies predominates in patients older than 50 years (65% male) and frequently presents with short-term memory loss and seizures (limbic encephalopathy), along with hyponatremia and sleep dysfunction. The MRI often shows increased FLAIR signal in one or both medial temporal lobes. In about 40% of patients, these symptoms are preceded by faciobrachial dystonic seizures, which consist of sudden, shortlasting, mainly distal muscle contractions involving the arm, face, or leg. These are unilateral but can independently affect both sides and occur multiple times during the day or night. About 15% of patients present with rapidly progressive cognitive decline, resembling a rap­ idly progressive dementia. Less than 5% of patients have thymoma. An association with the human leukocyte antigen (HLA) haplotypes DRB1∗07:01, DQB1∗02:02, DQA1∗02:01, and DRB4 has been identi­ fied. All symptoms, including faciobrachial dystonic seizures, respond to immunotherapy, although about two-thirds of patients are left with memory or cognitive deficits. Despite the improvement with initial immunotherapy, video-polysomnography or prolonged electroen­ cephalogram studies frequently uncover persistent alterations (facio­ brachial dystonic seizures, other seizures, rapid eye movement [REM] sleep behavior disorder) only detectable during sleep. These altera­ tions, which might contribute to residual memory or cognitive deficits, respond to additional or prolonged immunotherapy. Encephalitis with contactin-associated protein-like 2 (Caspr2) anti­ bodies predominates in patients older than 50 years and is associated with a form of encephalitis with three or more of the following core symptoms: encephalopathy (which can be similar to limbic encephali­ tis), cerebellar symptoms, peripheral nervous system hyperexcitability, dysautonomia, insomnia, neuropathic pain, and weight loss. Patients with Morvan syndrome, which includes clinical features of encephalitis (confusion, hallucinations, prominent sleep dysfunction, or “agrypnia excitata”), autonomic alterations, and peripheral nerve hyperexcitabil­ ity or neuromyotonia, usually have Caspr2 antibodies. About 20% of patients with Caspr2 antibody–associated syndromes have thymoma; this percentage is higher (~50%) in patients with Morvan syndrome. An association of Caspr2 antibody–associated syndromes with HLA DRB1∗11.01 has been reported. Encephalitis with dipeptidyl-peptidase-like protein-6 (DPPX) anti­ bodies is usually preceded or develops concurrently with diarrhea, other gastrointestinal symptoms, and substantial loss of weight that often suggest the presence of a gastrointestinal disease. Neurologic symptoms include agitation, hallucinations, paranoid delusions, and features of CNS hyperexcitability such as hyperekplexia, tremor, myoc­ lonus, nystagmus, or seizures. Some patients develop a clinical picture similar to progressive encephalomyelitis with rigidity and myoclonus. The few patients reported with an associated tumor usually had B-cell neoplasms. Encephalitis with antibodies against neurexin 3 alpha does not have distinctive clinical features; the experience is limited, and the disorder does not appear to be associated with cancer. Anti-IgLON5 disease is a chronic or subacute encephalopathy that characteristically is associated with REM and non-REM (NREM) parasomnia along with obstructive sleep apnea that may be preceded or accompanied by bulbar symptoms (mainly dysphagia and stridor due to vocal cord palsy), unsteadiness, movement disorders (chorea, craniofacial dyskinesias), oculomotor dysfunction, and, in less than half of cases, cognitive decline. The median age of the patients is in the early 60s, and men and women are equally affected. The sleep disorder is characterized by abnormal sleep initiation with undifferentiated NREM sleep associated with frequent vocalizations and quasi-purposeful movements. Brain MRI is unrevealing or demonstrates minor changes of unclear clinical relevance; the CSF is usually normal or may show transient lymphocytic pleocytosis. It is not associated with cancer but shows a strong association with the HLA-DRB1∗10:01 and HLADQB1∗05 haplotypes, which are present in 60% of patients. The response to immunotherapy is poor. In some patients, neuropathologic studies show a neuronal tauopathy predominantly involving the hypo­ thalamus and tegmentum of the brainstem; however, not all autopsy studies show deposits of hyperphosphorylated tau, and in some patients, mild inflammatory infiltrates have been identified. With the exception of patients with anti-IgLON5 disease, who rarely respond to treatment, most patients with autoimmune or paraneoplas­ tic encephalopathies associated with antibodies against cell-surface or synaptic proteins respond to immunotherapy and treatment of the tumor (if appropriate). Although there are no specific standardized treatment protocols, the most frequent approach is similar to that indi­ cated for anti-NMDAR encephalitis and consists of progressive escala­ tion of immunotherapy using first a combination of glucocorticoids, IVIg, and plasma exchange, and then, if there is no response, rituximab or cyclophosphamide. Encephalitis with MOG antibodies can present with a clinical picture suggestive of autoimmune encephalitis related to neuronal antibodies. Most patients with MOG antibody–associated syndromes are children and young adults who present with optic neuritis, myelitis, brainstem (mainly pons) and cerebellar symptoms, or acute disseminated enceph­ alomyelitis (ADEM). About 85% of patients with these syndromes respond to immunotherapy, although relapses occur in about 30% of cases. Besides these syndromes, there is a small group of adults and children who present with unilateral or bilateral cortical encephalitis, and their response to treatment is variable. In children, two pheno­ types of poor prognosis include ADEM-like relapses progressing to leukodystrophy-like features and extensive cortical encephalitis evolv­ ing to atrophy (Fig. 99-2D). In general, MOG antibody syndromes are not associated with tumors. ■ ■PARANEOPLASTIC CEREBELLAR DEGENERATION This disorder is often preceded by a prodrome that may include dizzi­ ness, oscillopsia, blurry or double vision, nausea, and vomiting. A few days or weeks later, patients develop dysarthria, gait and limb ataxia, and variable dysphagia. The examination usually shows downbeating nystagmus and, rarely, opsoclonus. Brainstem dysfunction or upgoing toes may occur. Early in the course, MRI studies are usually normal; later, the MRI reveals cerebellar atrophy. The disorder results from extensive degeneration of Purkinje cells, with variable involvement of other cerebellar cortical neurons, deep cerebellar nuclei, and spinocer­ ebellar tracts. The tumors more frequently involved are SCLC, cancer of the breast and ovary, and Hodgkin’s lymphoma. Anti-Yo (PCA1) antibodies in patients with breast or gynecologic cancers typically are associated with prominent or pure cerebellar degeneration. A variable degree of cerebellar dysfunction can be asso­ ciated with virtually any of the antibodies and PND of the CNS shown in Table 99-2. A number of single case reports have described neuro­ logic improvement after tumor removal, plasma exchange, IVIg, cyclo­ phosphamide, rituximab, or glucocorticoids. However, most patients with paraneoplastic cerebellar degeneration and any of the antibodies shown in Table 99-2 do not improve with treatment; an exception are the cerebellar syndromes associated with antibodies against surface antigens (e.g., Tr antibodies and Hodgkin’s lymphoma, VGCC antibod­ ies and SCLC), which are more responsive to immunotherapy. Antibody-associated cerebellar symptoms can also occur without cancer association. The most common is cerebellar ataxia with anti­ bodies against GAD65 (an intracellular synaptic protein). The median age at diagnosis is 60 years and 75% of cases are women. Concurrent organ-specific autoimmune diseases, mainly type 1 diabetes, are pres­ ent in 80% of patients. The clinical course is chronic, but in 40% of patients, the presentation is subacute (<6 months). Response to immu­ notherapy is poor. Subacute onset of symptoms and prompt initiation of immunotherapy are associated with a better chance for improve­ ment. By contrast, the cerebellar syndrome associated with mGluR1 antibodies is more responsive to immunotherapy, and a substantial improvement occurs in almost half of the patients. Immunotherapy is also effective in patients with GluK2 antibodies, who can present with cerebellitis and posterior fossa edema with compression of the fourth ventricle, and in those with septin-5 antibodies. Although septin-5 is an intracellular antigen, it is likely exposed to the cell surface during the process of endo- and exocytosis at synaptic terminals. CHAPTER 99 Paraneoplastic Neurologic Syndromes and Autoimmune Encephalitis ■ ■PARANEOPLASTIC OPSOCLONUS-MYOCLONUS SYNDROME Opsoclonus is a disorder of eye movement characterized by involuntary, chaotic saccades that occur in all directions of gaze; it is frequently associated with myoclonus and ataxia. Opsoclonus-myoclonus may be cancer-related or idiopathic. When the cause is paraneoplastic, the tumors involved are usually cancer of the lung and breast in adults and neuroblastoma in children. The pathologic substrate of opsoclonusmyoclonus is unclear, but studies suggest that disinhibition of the fas­ tigial nucleus of the cerebellum is involved. Most patients do not have neuronal antibodies. A small subset of patients with ataxia, opsoclonus, and other eye-movement disorders have Ri antibodies; these patients may also develop muscle rigidity, laryngeal spasms, and autonomic dysfunction. The tumors most frequently involved in anti-Ri-associated syndromes are breast, ovarian, and lung cancers. If the tumor is not successfully treated, the syndrome in adults often progresses to encephalopathy, coma, and death. In addition to treating the tumor, symptoms may respond to immunotherapy (glucocorticoids, plasma exchange, and/or IVIg). At least 50% of children with opsoclonus-myoclonus have an underlying neuroblastoma. Hypotonia, ataxia, behavioral changes, and irritability are frequent accompanying symptoms. Neurologic symp­ toms often improve with treatment of the tumor and glucocorticoids, adrenocorticotropic hormone (ACTH), plasma exchange, IVIg, ritux­ imab, or cyclophosphamide. Many patients are left with psychomotor retardation and behavioral and sleep problems. ■ ■PARANEOPLASTIC SYNDROMES OF THE SPINAL CORD The number of reports of paraneoplastic spinal cord syndromes, such as subacute motor neuronopathy and acute necrotizing myelopathy, has decreased over the years. This may represent a true decrease in incidence, due to improved and prompt oncologic interventions, or the identification of nonparaneoplastic etiologies. Some patients with cancer or lymphoma develop upper or lower motor neuron dysfunction or both, resembling amyotrophic lateral sclerosis. It is unclear whether these disorders have a paraneoplastic etiology or simply coincide with the presence of cancer. Paraneoplastic myelitis may present with upper or lower motor neu­ ron symptoms, segmental myoclonus, sensory deficits, sphincter dys­ function, and neurogenic pruritus and can be the first manifestation of encephalomyelitis. The spine MRI usually shows longitudinally exten­ sive, symmetric tract or gray matter abnormalities in the spinal cord. It is mainly associated with breast and lung carcinomas and with CRMP5 or amphiphysin antibodies. The prognosis is poor. Neuromyelitis optica (NMO) with aquaporin 4 antibodies may occur in rare instances as a paraneoplastic manifestation of a cancer. NMO is discussed in detail in Chap. 456. ■ ■PARANEOPLASTIC STIFF-PERSON SYNDROME This disorder is characterized by progressive muscle rigidity, stiff­ ness, and painful spasms triggered by auditory, sensory, or emotional stimuli. Rigidity mainly involves the lower trunk and legs, but it can affect the upper extremities and neck. Sometimes, only one extremity is affected (stiff-limb syndrome). Symptoms improve with sleep and general anesthetics. Electrophysiologic studies demonstrate continuous motor unit activity. The associated antibodies target proteins (GAD65, amphiphysin) involved in the function of inhibitory synapses that use γ-aminobutyric acid (GABA) or glycine as neurotransmitters. The presence of amphiphysin antibodies usually indicates a paraneoplastic etiology related to SCLC and breast cancer. By contrast, GAD antibod­ ies may occur in some cancer patients but are much more frequently present in the nonparaneoplastic disorder. GlyR antibodies may occur in some patients with stiff-person syndrome; these antibodies are more frequently detectable in patients with PERM (Fig. 99-5). PART 4 Oncology and Hematology Optimal treatment of stiff-person syndrome requires therapy of the underlying tumor, glucocorticoids, and symptomatic use of drugs that enhance GABA-ergic transmission (diazepam, baclofen, sodium valproate, tiagabine, vigabatrin). IVIg and plasma exchange are tran­ siently effective in some patients, and there are reports of responses FIGURE 99-5  Schematic representation of an inhibitory synapse showing the main autoimmune targets (GAD, amphiphysin, GABA receptor, and glycine receptor) and the corresponding neurologic disorders. GAD antibodies predominantly occur in stiff-person syndrome (SPS), cerebellar ataxia, and epilepsy, sometimes in the setting of encephalitis. Amphiphysin antibodies are markers of paraneoplastic SPS and breast cancer, GlyR antibodies often associate with progressive encephalomyelitis with rigidity and myoclonus (PERM), and GABAA receptor antibodies occur in a form of autoimmune encephalitis that is frequently associated with refractory seizures and status epilepticus. (Modified from F Graus et al: Nat Rev Neurol 16:353, 2020.) to rituximab and CD19 CAR T-cell therapy in patients who did not respond to other treatments. ■ ■PARANEOPLASTIC SENSORY NEURONOPATHY OR DORSAL ROOT GANGLIONOPATHY This syndrome is characterized by sensory deficits that may be symmetric or asymmetric, painful dysesthesias, radicular pain, and decreased or absent reflexes. All modalities of sensation and any part of the body including face and trunk can be involved. Special senses such as taste and hearing can also be affected. Electrophysiologic stud­ ies show decreased or absent sensory nerve potentials with normal or near-normal motor conduction velocities. Symptoms result from an immune-mediated process that targets the dorsal root ganglia, causing neuronal loss and secondary degeneration of the posterior columns of the spinal cord. The dorsal and, less frequently, the anterior nerve roots and peripheral nerves may also be involved. This disorder often precedes or is associated with encephalomyelitis and autonomic dys­ function and has the same immunologic and oncologic associations (Hu antibodies, SCLC). As with anti-Hu-associated encephalomyelitis, the therapeutic approach focuses on prompt treatment of the tumor and cytotoxic T-cell–mediated mechanisms. Glucocorticoids occasionally produce clinical stabilization or improvement. The benefit of IVIg and plasma exchange is not proven. ■ ■PARANEOPLASTIC PERIPHERAL NEUROPATHIES These disorders may develop any time during the course of the neo­ plastic disease. Neuropathies occurring at late stages of cancer or lymphoma usually cause mild to moderate sensorimotor deficits due to axonal degeneration of unclear etiology. These neuropathies are often masked by concurrent neurotoxicity from chemotherapy and other cancer therapies. In contrast, the neuropathies that develop in the early stages of cancer frequently show a rapid progression, sometimes with a relapsing and remitting course, and evidence of inflammatory infiltrates and axonal loss or demyelination. Besides the subacute onset, an asymmetric distribution of symptoms, presence of neuropathic pain and dysautonomia, clinical or neuroimaging evidence of involvement of the spinal cord or nerve roots, and detection of an axonal pattern in the electrophysiological studies are features that suggest the possibility of a paraneoplastic etiology. The response to treatment is usually poor, but if demyelinating features predominate (Chaps. 457 and 458), IVIg, plasma exchange, or glucocorticoids may improve symptoms. Occa­ sionally, CRMP5 antibodies are present; detection of Hu antibodies suggests concurrent dorsal root ganglionitis. Guillain-Barré syndrome (Chap. 458) and brachial plexitis (Chap. 457) have occasionally been reported in patients with Hodgkin’s lymphoma, but there is no clear evidence of a paraneoplastic association. Diseases associated with paraproteinemia such as multiple myeloma, osteosclerotic myeloma, cryoglobulinemia, amyloidosis, Waldenström’s macroglobulinemia, or POEMS (polyneuropathy, organomegaly, endo­ crinopathy, M-protein spike, and skin manifestations) syndrome, among others, may cause neuropathy by a variety of mechanisms, including compression of roots and plexuses by metastasis to verte­ bral bodies and pelvis, by deposits of amyloid in peripheral nerves, or through a direct interaction of the abnormal immunoglobulin with peripheral nerve antigens. In other patients, the mechanisms under­ lying the neuropathy remain unknown and paraneoplastic immunemediated mechanisms have not been ruled out. Neuropathies more often occur with IgM paraproteinemia followed by IgG and IgA. The phenotype of the neuropathy and likelihood of improvement with suc­ cessful treatment of the paraproteinemia are dependent on the under­ lying hematologic disorder (Chap. 458). Vasculitis of the nerve and muscle causes a painful symmetric or asymmetric distal axonal sensorimotor neuropathy with variable proximal weakness. It predominantly affects elderly men and is associ­ ated with an elevated erythrocyte sedimentation rate and increased CSF protein concentration. SCLC and lymphoma are the primary tumors involved. Glucocorticoids and cyclophosphamide often result in neurologic improvement. Peripheral nerve hyperexcitability (neuromyotonia, or Isaacs’ syn­ drome) is characterized by spontaneous and continuous muscle fiber activity of peripheral nerve origin. Clinical features include cramps, muscle twitching (fasciculations or myokymia), stiffness, delayed muscle relaxation (pseudomyotonia), and spontaneous or evoked carpal or pedal spasms. The involved muscles may be hypertrophic, and some patients develop paresthesias and hyperhidrosis. The elec­ tromyogram (EMG) shows fibrillations; fasciculations; and doublet, triplet, or multiplet single-unit (myokymic) discharges that have a high intraburst frequency. Some patients have Caspr2 antibodies usually in the context of Morvan syndrome, but most patients with isolated neu­ romyotonia are antibody negative. The disorder often occurs without cancer; if paraneoplastic, benign and malignant thymomas and SCLC are the usual tumors. Phenytoin, carbamazepine, and plasma exchange improve symptoms. Paraneoplastic autonomic neuropathy usually develops as a compo­ nent of other disorders, such as LEMS and encephalomyelitis. It may rarely occur as a pure or predominantly autonomic neuropathy with cholinergic or adrenergic dysfunction at the pre- or postganglionic levels. Patients can develop several life-threatening complications, such as gastrointestinal paresis with pseudo-obstruction, cardiac dys­ rhythmias, and postural hypotension. Other clinical features include abnormal pupillary responses, dry mouth, anhidrosis, erectile dys­ function, and problems with sphincter control. The disorder occurs in association with several tumors, including SCLC, cancer of the pancreas or testis, carcinoid tumors, and lymphoma. Because auto­ nomic symptoms can be the presenting feature of encephalomyelitis, serum Hu and CRMP5 antibodies should be sought. Antibodies to ganglionic (α3-type) neuronal acetylcholine receptors are the cause of autoimmune autonomic ganglionopathy, a disorder that frequently occurs without cancer association (Chap. 451). ■ ■LAMBERT-EATON MYASTHENIC SYNDROME LEMS is discussed in Chap. 459. ■ ■MYASTHENIA GRAVIS Myasthenia gravis is discussed in Chap. 459. ■ ■POLYMYOSITIS-DERMATOMYOSITIS Polymyositis and dermatomyositis are discussed in detail in Chap. 377. ■ ■IMMUNE-MEDIATED NECROTIZING MYOPATHY Patients with this syndrome develop myalgias and rapid progression of weakness involving the extremities, neck, pharyngeal, respiratory, and sometimes cardiac muscles. Serum muscle enzymes are elevated, and muscle biopsy shows extensive necrosis with minimal or absent inflammation and sometimes deposits of complement. The disorder may occur without cancer association (sometimes as a result of statin exposure, connective tissue disease, or HIV) or with cancer asso­ ciation. Patients with antibodies against 3-hydroxy-3-methylglutarylcoenzyme A reductase (HMGCR) and seronegative patients are more likely to have an underlying cancer than those with antibodies against signal recognition particle. No specific type of cancer has been found to be predominant. Successful treatment of the tumor and aggressive immunotherapy (steroids, IVIg, and steroid-sparing immunosuppres­ sants) may lead to complete or substantial recovery. Immune-mediated necrotizing myopathy is discussed in Chap. 377. CHAPTER 99 Paraneoplastic Neurologic Syndromes and Autoimmune Encephalitis ■ ■PARANEOPLASTIC VISUAL SYNDROMES This group of disorders involves the retina and, less frequently, the uvea and optic nerves. The term cancer-associated retinopathy is used to describe paraneoplastic cone and rod dysfunction characterized by photosensitivity, progressive loss of vision and color perception, central or ring scotomas, night blindness, and attenuation of photopic and scotopic responses in the electroretinogram (ERG). The most com­ monly associated tumor is SCLC. Melanoma-associated retinopathy affects patients with metastatic cutaneous melanoma. Patients develop acute onset of night blindness and shimmering, flickering, or pulsating photopsias that often progress to visual loss. The ERG shows reduced b-waves with normal dark adapted a-waves. Paraneoplastic optic neu­ ritis and uveitis can develop in association with encephalomyelitis. Patients with paraneoplastic uveitis and optic neuritis may harbor CRMP5 antibodies. Some paraneoplastic retinopathies are associated with serum anti­ bodies that specifically react with the subset of retinal cells undergoing degeneration, supporting an immune-mediated pathogenesis. The best-characterized retinal antibodies are against recoverin and have been described in patients with SCLC and cancer-associated retinopa­ thy. However, the specificity of this and other retinal antibodies is low as they have also been reported in nonparaneoplastic autoimmune and nonautoimmune retinopathies. Paraneoplastic retinopathies rarely show substantial improvement after treatment of the tumor and immu­ notherapy; however, stabilization of symptoms and partial responses to a variety of immunotherapies (glucocorticoids, plasma exchange, IVIg, rituximab, or alemtuzumab) have been reported. ■ ■FURTHER READING Armangue T et al: Associations of paediatric demyelinating and encephalitic syndromes with myelin oligodendrocyte glycoprotein antibodies: A multicentre observational study. Lancet Neurol 19:234, 2020. Armangue T et al: Neurological complications in herpes simplex encephalitis: Clinical, immunological and genetic studies. Brain 146:4306, 2023. Cellucci T et al: Clinical approach to the diagnosis of autoimmune encephalitis in the pediatric patient. Neurol Neuroimmunol Neuro­ inflamm 7:e663, 2020. Dalmau J, Graus F: Autoimmune Encephalitis and Related Disorders of the Nervous System. Cambridge, Cambridge University Press, 2022. # 30 - SECTION 2 Hematopoietic Disorders ## SECTION 2 Hematopoietic Disorders traditionally been performed by oncologists, but the magnitude of the problem mandates that primary care providers and preventive medi­ cine specialists be trained in the follow-up of treated cancer patients in remission or undergoing chronic therapy. All former cancer patients should undergo surveillance for recurrence and second malignancies and be monitored for long-term effects of treatment; however, nearly all recurrences are detected because of symptoms. Health promotion and disease prevention with age- and sex-specific routine screening tests (e.g., colonoscopy, Pap smears, mammography, human papillo­ mavirus vaccination, dual-energy x-ray absorptiometry scans) should be a focus of survivorship care along with psychosocial well-being. Annual mammography should start no later than 10 years after breast radiation. Patients receiving radiation fields encompassing thyroid tis­ sue should have regular thyroid examinations and TSH testing. Local­ ized pain or palpable abnormality in a previously radiated field should prompt radiographic evaluation. Patients treated with alkylating agents or topoisomerase inhibitors should have a complete blood count every 6–12 months, and cytopenias, abnormal cells on peripheral smear, or macrocytosis should be evaluated with bone marrow biopsy and aspi­ rate and include cytogenetics, flow cytometry, or fluorescence in situ hybridization (FISH) studies as appropriate. As the population of cancer survivors increases and patients live longer, cancer survivorship has become increasingly important, and the Institute of Medicine and National Research Council have pub­ lished a monograph entitled From Cancer Patient to Cancer Survivor: Lost in Transition. The monograph proposes a plan that would inform clinicians caring for cancer survivors of the complete details of patients’ previous treatments, complications thereof, signs and symptoms of late effects, and recommended screening and follow-up procedures. PART 4 Oncology and Hematology OUTLOOK Survivorship care is a burgeoning problem facing oncologists today. The challenge is to develop cancer treatments that maximize clini­ cal benefit including cure of disease while also mitigating the risks of long-term toxicity. As cancer treatments continue to improve, the prevalence of cancer survivors increases along with an increase in life expectancy. Further, since emerging therapies often have improved tolerability profiles, a greater number of patients with advanced age or comorbid medical conditions will become cancer survivors with per­ sistent treatment-related toxicities. As treatment paradigms continue to evolve, the nature and biologic basis for toxicities will change and phar­ macovigilance of new therapies is critical. Advances in genomic medi­ cine may allow for more risk-stratified personalized care. The choice of therapy needs to be tailored to the type of cancer, expected outcomes, and patient-related risk factors for both acute and long-term toxicities. After therapy is complete, longitudinal monitoring of the health and health-related quality of life of cancer survivors is critical since the inci­ dence of late effects of treatment does not appear to plateau over time. Acknowledgment We would like to acknowledge the contribution of Carl E. Freter who coauthored a previous version of this chapter; material from his chapter was retained in this version. ■ ■FURTHER READING Armenian SH et al: Cardiovascular disease in survivors of childhood cancer: Insights into epidemiology, pathophysiology, and prevention. J Clin Oncol 36:2135, 2018. Brinkman TM et al: Psychological symptoms, social outcomes, socioeconomic attainment, and health behaviors among survivors of childhood cancer: Current state of the literature. J Clin Oncol 36:2190, 2018. Chow EJ et al: New agents, emerging late effects, and the development of precision survivorship. J Clin Oncol 36:2231, 2018. Ehrhardt MJ et al: Health care transitions among adolescents and young adults with cancer. J Clin Oncol 42:743, 2024. Lustberg MB et al: Mitigating long-term and delayed adverse events associated with cancer treatment: Implications for survivorship. Nat Rev Clin Oncol 20:527, 2023. Rowland JH et al: Survivorship science at the NIH: Lessons learned from grants funded in fiscal year 2016. J Natl Cancer Inst 111:109, 2019. Shapiro CL: Cancer survivorship. N Engl J Med 379:2438, 2018. Shapiro CL et al: ReCAP: ASCO core curriculum for cancer survivor­ ship education. J Oncol Pract 12:e08, 2016. Shree T et al: Impaired immune health in survivors of diffuse large B-cell lymphoma. J Clin Oncol 38:1664, 2020. Turcotte LM et al: Risk, risk factors, and surveillance of subsequent malignant neoplasms in survivors of childhood cancer: A review. J Clin Oncol 36:2145, 2018. Section 2 Hematopoietic Disorders David T. Scadden, Dan L. Longo Hematopoietic Stem Cells All of the cell types in the blood and some cells in every tissue of the body are derived from hematopoietic (hemo: blood; poiesis: creation) stem cells. If the hematopoietic stem cell is damaged and can no longer function (e.g., due to a nuclear accident), a person would survive 2–4 weeks in the absence of extraordinary support measures. With the clinical use of hematopoietic stem cells, tens of thousands of lives are saved each year (Chap. 119). Stem cells produce hundreds of billions of blood cells daily from a stem cell pool that is estimated to be only 20,000–200,000. How stem cells do this, how they persist for many decades despite the production demands, and how they may be better used in clinical care are important issues in medicine. The study of blood cell production has become a paradigm for how other tissues may be organized and regulated. Basic research in hema­ topoiesis includes defining stepwise molecular changes accompanying functional changes in maturing cells, aggregating cells into functional subgroups, and demonstrating hematopoietic stem cell regulation by a specialized microenvironment; these concepts are worked out in hematology and offer models for other tissues. Moreover, these con­ cepts may not be restricted to normal tissue function but extend to malignancy. CARDINAL FUNCTIONS OF HEMATOPOIETIC STEM CELLS All stem cell types have two cardinal functions: self-renewal and dif­ ferentiation (Fig. 101-1). Stem cells exist to generate, maintain, and repair tissues. They function successfully if they can replace a wide variety of shorter-lived mature cells over prolonged periods. The pro­ cess of self-renewal (see below) assures that a stem cell population can be sustained over time. Without self-renewal, the stem cell pool would become exhausted and tissue maintenance would not be possible. The process of differentiation leads to production of the effectors of tissue function: mature cells. Without proper differentiation, the integrity of tissue function would be compromised and organ failure or neoplasia would ensue. In the blood, mature cells have variable average life spans, ranging from hours for mature neutrophils to a few months for red blood cells to many years for memory lymphocytes. However, the stem cell pool is the central, durable source of all blood and immune cells, maintaining a capacity to produce a broad range of cells from a single cell source, yet keeping itself vigorous over decades of life. As an individual stem cell divides, it has the capacity to accomplish one of three division outcomes: two stem cells, two cells destined for differentiation, or one stem cell and one differentiating cell. The former two outcomes are the # 31 - 101 Hematopoietic Stem Cells ### 101 Hematopoietic Stem Cells traditionally been performed by oncologists, but the magnitude of the problem mandates that primary care providers and preventive medi­ cine specialists be trained in the follow-up of treated cancer patients in remission or undergoing chronic therapy. All former cancer patients should undergo surveillance for recurrence and second malignancies and be monitored for long-term effects of treatment; however, nearly all recurrences are detected because of symptoms. Health promotion and disease prevention with age- and sex-specific routine screening tests (e.g., colonoscopy, Pap smears, mammography, human papillo­ mavirus vaccination, dual-energy x-ray absorptiometry scans) should be a focus of survivorship care along with psychosocial well-being. Annual mammography should start no later than 10 years after breast radiation. Patients receiving radiation fields encompassing thyroid tis­ sue should have regular thyroid examinations and TSH testing. Local­ ized pain or palpable abnormality in a previously radiated field should prompt radiographic evaluation. Patients treated with alkylating agents or topoisomerase inhibitors should have a complete blood count every 6–12 months, and cytopenias, abnormal cells on peripheral smear, or macrocytosis should be evaluated with bone marrow biopsy and aspi­ rate and include cytogenetics, flow cytometry, or fluorescence in situ hybridization (FISH) studies as appropriate. As the population of cancer survivors increases and patients live longer, cancer survivorship has become increasingly important, and the Institute of Medicine and National Research Council have pub­ lished a monograph entitled From Cancer Patient to Cancer Survivor: Lost in Transition. The monograph proposes a plan that would inform clinicians caring for cancer survivors of the complete details of patients’ previous treatments, complications thereof, signs and symptoms of late effects, and recommended screening and follow-up procedures. PART 4 Oncology and Hematology OUTLOOK Survivorship care is a burgeoning problem facing oncologists today. The challenge is to develop cancer treatments that maximize clini­ cal benefit including cure of disease while also mitigating the risks of long-term toxicity. As cancer treatments continue to improve, the prevalence of cancer survivors increases along with an increase in life expectancy. Further, since emerging therapies often have improved tolerability profiles, a greater number of patients with advanced age or comorbid medical conditions will become cancer survivors with per­ sistent treatment-related toxicities. As treatment paradigms continue to evolve, the nature and biologic basis for toxicities will change and phar­ macovigilance of new therapies is critical. Advances in genomic medi­ cine may allow for more risk-stratified personalized care. The choice of therapy needs to be tailored to the type of cancer, expected outcomes, and patient-related risk factors for both acute and long-term toxicities. After therapy is complete, longitudinal monitoring of the health and health-related quality of life of cancer survivors is critical since the inci­ dence of late effects of treatment does not appear to plateau over time. Acknowledgment We would like to acknowledge the contribution of Carl E. Freter who coauthored a previous version of this chapter; material from his chapter was retained in this version. ■ ■FURTHER READING Armenian SH et al: Cardiovascular disease in survivors of childhood cancer: Insights into epidemiology, pathophysiology, and prevention. J Clin Oncol 36:2135, 2018. Brinkman TM et al: Psychological symptoms, social outcomes, socioeconomic attainment, and health behaviors among survivors of childhood cancer: Current state of the literature. J Clin Oncol 36:2190, 2018. Chow EJ et al: New agents, emerging late effects, and the development of precision survivorship. J Clin Oncol 36:2231, 2018. Ehrhardt MJ et al: Health care transitions among adolescents and young adults with cancer. J Clin Oncol 42:743, 2024. Lustberg MB et al: Mitigating long-term and delayed adverse events associated with cancer treatment: Implications for survivorship. Nat Rev Clin Oncol 20:527, 2023. Rowland JH et al: Survivorship science at the NIH: Lessons learned from grants funded in fiscal year 2016. J Natl Cancer Inst 111:109, 2019. Shapiro CL: Cancer survivorship. N Engl J Med 379:2438, 2018. Shapiro CL et al: ReCAP: ASCO core curriculum for cancer survivor­ ship education. J Oncol Pract 12:e08, 2016. Shree T et al: Impaired immune health in survivors of diffuse large B-cell lymphoma. J Clin Oncol 38:1664, 2020. Turcotte LM et al: Risk, risk factors, and surveillance of subsequent malignant neoplasms in survivors of childhood cancer: A review. J Clin Oncol 36:2145, 2018. Section 2 Hematopoietic Disorders David T. Scadden, Dan L. Longo Hematopoietic Stem Cells All of the cell types in the blood and some cells in every tissue of the body are derived from hematopoietic (hemo: blood; poiesis: creation) stem cells. If the hematopoietic stem cell is damaged and can no longer function (e.g., due to a nuclear accident), a person would survive 2–4 weeks in the absence of extraordinary support measures. With the clinical use of hematopoietic stem cells, tens of thousands of lives are saved each year (Chap. 119). Stem cells produce hundreds of billions of blood cells daily from a stem cell pool that is estimated to be only 20,000–200,000. How stem cells do this, how they persist for many decades despite the production demands, and how they may be better used in clinical care are important issues in medicine. The study of blood cell production has become a paradigm for how other tissues may be organized and regulated. Basic research in hema­ topoiesis includes defining stepwise molecular changes accompanying functional changes in maturing cells, aggregating cells into functional subgroups, and demonstrating hematopoietic stem cell regulation by a specialized microenvironment; these concepts are worked out in hematology and offer models for other tissues. Moreover, these con­ cepts may not be restricted to normal tissue function but extend to malignancy. CARDINAL FUNCTIONS OF HEMATOPOIETIC STEM CELLS All stem cell types have two cardinal functions: self-renewal and dif­ ferentiation (Fig. 101-1). Stem cells exist to generate, maintain, and repair tissues. They function successfully if they can replace a wide variety of shorter-lived mature cells over prolonged periods. The pro­ cess of self-renewal (see below) assures that a stem cell population can be sustained over time. Without self-renewal, the stem cell pool would become exhausted and tissue maintenance would not be possible. The process of differentiation leads to production of the effectors of tissue function: mature cells. Without proper differentiation, the integrity of tissue function would be compromised and organ failure or neoplasia would ensue. In the blood, mature cells have variable average life spans, ranging from hours for mature neutrophils to a few months for red blood cells to many years for memory lymphocytes. However, the stem cell pool is the central, durable source of all blood and immune cells, maintaining a capacity to produce a broad range of cells from a single cell source, yet keeping itself vigorous over decades of life. As an individual stem cell divides, it has the capacity to accomplish one of three division outcomes: two stem cells, two cells destined for differentiation, or one stem cell and one differentiating cell. The former two outcomes are the Stem cell Self-renewal Differentiation Stem cell Differentiated cells FIGURE 101-1  Signature characteristics of the stem cell. Stem cells have two essential features: the capacity to differentiate into a variety of mature cell types and the capacity for self-renewal. Intrinsic factors associated with self-renewal include expression of Bmi-1, Gfi-1, PTEN, STAT5, Tel/Atv6, p21, p18, MCL-1, Mel-18, RAE28, and HoxB4. Extrinsic signals for self-renewal include Notch, Wnt, SHH, angiogenin, and Tie2/Ang-1. Based mainly on murine studies, hematopoietic stem cells express the following cell surface molecules: CD34, Thy-1 (CD90), c-Kit receptor (CD117), CD133, CD164, and c-Mpl (CD110, also known as the thrombopoietin receptor). result of symmetric cell division, whereas the latter indicates a different outcome for the two daughter cells—an event termed asymmetric cell division. The relative balance for these types of outcomes may change during development and under particular kinds of demands on the stem cell pool. ■ ■DEVELOPMENTAL BIOLOGY OF HEMATOPOIETIC STEM CELLS During development, blood cells are produced at different sites. Initially, the yolk sac provides oxygen-carrying red blood cells and many of the macrophage-like cells that are resident in tissues: cells like microglia in the brain. The placenta and several sites of intraembryonic blood cell production then become involved in sequential order. These move from the genital ridge at a site where the aorta, gonadal tissue, and mesonephros are emerging to the fetal liver and then, in the sec­ ond trimester, to the bone marrow and spleen. As the location of stem cells changes, the cells they produce also change. The yolk sac provides red cells expressing embryonic hemoglobins and tissue-resident mac­ rophages. Intraembryonic sites of hematopoiesis generate stem cells, red cells, platelets, and the circulating cells of innate immunity. The production of the cells of adaptive immunity occurs then as well but becomes robust as the thymus forms and the bone marrow is colonized in the second trimester. Stem cell proliferation remains high, even in the bone marrow, until shortly after birth, when it appears to dramati­ cally decline. The cells in the bone marrow are thought to arrive by the bloodborne transit of cells from the fetal liver after calcification of the long bones has begun. The presence of stem cells in the circulation is not unique to a time window in development, however, as hemato­ poietic stem cells circulate throughout life. The time that stem cells spend freely circulating appears to be brief (measured in minutes in the mouse), but the stem cells that do circulate are functional and can be used for transplantation. The number of stem cells that circulate can be increased in a number of ways to facilitate their harvest and transfer to the same or a different host. ■ ■MOBILITY OF HEMATOPOIETIC STEM CELLS Cells entering and exiting the bone marrow do so through a series of molecular interactions. Circulating stem cells (through CD162 and CD44) engage the lectins (carbohydrate binding proteins) P- and E-selectin on the endothelial surface to slow the movement of the cells to a rolling phenotype. Stem cell integrins are then activated and accomplish firm adhesion between the stem cell and vessel wall, with a particularly important role for stem cell VCAM-1 engaging endothelial VLA-4. The chemokine CXCL12 (SDF1) interacting with stem cell CXCR4 receptors and ionic calcium interacting with the calcium-sensing receptor are important in the process of stem cells getting from the circulation to where they engraft in the bone marrow. This is particularly true in the developmental move from fetal liver to bone marrow. In the adult, the role for CXCR4 is in retention of stem cells in the bone marrow as well as getting them there. Interrupting that retention process through specific molecular blockers of the CXCR4/CXCL12 interaction, cleavage of CXCL12, or downregulation of the CXCR4 receptor can result in the release of stem cells into the circulation. This process is an increasingly important aspect of recovering stem cells for therapeutic use as it has permitted the harvesting process to be done by leukapheresis rather than bone marrow punctures in the operating room. Granulocyte colony-stimulating factor and plerixafor, a mac­ rocyclic compound that can block CXCR4, are both used clinically to mobilize marrow hematopoietic stem cells for transplant. ■ ■HEMATOPOIETIC STEM CELL MICROENVIRONMENT The concept of a specialized microenvironment, or stem cell niche, was first proposed to explain why cells derived from the bone marrow of one animal could be used in transplantation and again be found in the bone marrow of the recipient. This niche is more than just a housing site for stem cells, however. It is an anatomic location where regula­ tory signals are provided that allow the stem cells to thrive, to expand if needed, and to provide varying amounts of descendant daughter cells. In addition, unregulated growth of stem cells may be problematic based on their undifferentiated state and self-renewal capacity. Thus, the niche also regulates the number of stem cells produced. In this manner, the niche has the dual function of serving as a site of nurture but imposing limits for stem cells: in effect, acting as both a nutritive and constraining home. CHAPTER 101 Hematopoietic Stem Cells The niche for blood stem cells changes with each of the sites of blood production during development, but for most of human life, it is located in the bone marrow. Within the bone marrow, the perivascular space particularly in regions of trabecular bone serves as a niche. The mesenchymal and endothelial cells of the marrow microvessels pro­ duce kit ligand and CXCL12, both known to be important for hema­ topoietic stem cells. Other cell types, such as sympathetic neurons, nonmyelinating Schwann cells, macrophages, megakaryocytes, osteo­ clasts, and osteoblasts, have been shown to regulate stem cells, some by direct and others by indirect effects. Extracellular matrix proteins like osteopontin and heparan sulfates also affect stem cell function. The endosteal region appears to be particularly important for transplanted cells, in part because many of the mesenchymal cells and sinusoidal blood vessels of the central marrow are disrupted by the conditioning regimens used to prepare a patient for transplantation. The function­ ing of the niche as a supportive context for stem cells is of obvious importance for maintaining hematopoiesis and in transplantation. An active area of study involves determining whether the niche is altered in disease as experimental models have shown that mutations in niche cells can lead to myeloid malignancies. ■ ■EXCESS CAPACITY OF HEMATOPOIETIC STEM CELLS In the absence of disease, one never runs out of hematopoietic stem cells. Indeed, serial transplantation studies in mice suggest that suf­ ficient stem cells are present to reconstitute several animals in succes­ sion, with each animal having normal blood cell production. The fact that allogeneic stem cell transplant recipients also never run out of blood cells over decades argues that even the limiting numbers of stem cells provided to them are sufficient. How stem cells respond to dif­ ferent conditions to increase or decrease their mature cell production remains poorly understood. Clearly, negative feedback mechanisms affect the level of production of most of the cells, leading to the normal tightly regulated blood cell counts. However, many of the regulatory mechanisms that govern production of more mature progenitor cells do not apply or apply differently to stem cells. Similarly, most of the molecules shown to be able to change the size of the stem cell pool have little effect on more mature blood cells. For example, the growth factor erythropoietin, which stimulates red blood cell production from precursor cells, has no effect on stem cells. Similarly, granulocyte colony-stimulating factor drives the rapid proliferation of granulocyte precursors but has little or no effect on the cell cycling of stem cells. Rather, it changes the location of stem cells by indirect means, altering molecules such as CXCL12 that tether stem cells to their niche. Mole­ cules shown to be important for altering the proliferation, self-renewal, or survival of stem cells, such as cyclin-dependent kinase inhibitors, transcription factors like Bmi-1, microRNA-processing enzymes like Dicer, or even metabolic regulators like pyruvate kinase isoforms, have little or different effects on progenitor cells. Hematopoietic stem cells have governing mechanisms that are distinct from the cells they generate. ■ ■HEMATOPOIETIC STEM CELL DIFFERENTIATION Hematopoietic stem cells sit at the base of a branching hierarchy of cells culminating in the many mature cell types that compose the blood and immune system (Fig. 101-2). The maturation steps leading to terminally differentiated and functional blood cells take place both as a consequence of intrinsic changes in gene expression and external, Stem Cells Progenitor Cells Lineage Committed PART 4 Oncology and Hematology LEF1, E2A, EBF, PAX-5 Common Lymphoid Progenitor B-Cell Progenitor IL7 NOTCH1 IL7 T/NK Cell Progenitor IKAROS PU1 IL7 Lymphomyeloid Potent Progenitor Hematopoietic stem cell cMyb Multipotent Progenitor Hox, Pbx1, SCL, GATA2, NOTCH Granulocyte Monocyte Progenitor SCF TPO GM-CSF GATA1, FOG NF-E2, SCL Rbtn2 Common Myeloid Progenitor IL3, SCF TPO Megakaryocyte Progenitor Megakaryocyte Erythroid Progenitor FIGURE 101-2  Hierarchy of hematopoietic differentiation. Stem cells are multipotent cells that are the source of all descendant cells and have the capacity to provide either long-term (measured in years) or short-term (measured in months) cell production. Progenitor cells have a more limited spectrum of cells they can produce and are generally a shorter-lived, highly proliferative population also known as transient amplifying cells. Precursor cells are cells committed to a single blood cell lineage but with a continued ability to proliferate; they do not have all the features of a fully mature cell. Mature cells are the terminally differentiated product of the differentiation process and are the effector cells of specific activities of the blood and immune system. Progress through the pathways is mediated by alterations in gene expression. The regulation of the differentiation by soluble factors and cell-cell communications within the bone marrow niche are still being defined. The transcription factors that characterize particular cell transitions are illustrated on the arrows; the soluble factors that contribute to the differentiation process are in blue. This picture is a simplification of the process. Active research is revealing multiple discrete cell types in the maturation of B cells and T cells and has identified cells that are biased toward one lineage or another (rather than uncommitted) in their differentiation. EPO, erythropoietin; RBC, red blood cell; SCF, stem cell factor; TPO, thrombopoietin. niche-directed or cytokine-directed changes in the cells. Our knowl­ edge of the details remains incomplete. As stem cells mature to pro­ genitors, precursors, and, finally, mature effector cells, they undergo a series of functional changes. These include the acquisition of functions defining mature blood cells, such as phagocytic capacity or hemoglobin synthesis. They also include the progressive loss of plasticity (i.e., the ability to become other cell types). For example, some myeloid progeni­ tors can make all cells in the myeloid series but none in the lymphoid series. As common myeloid progenitors mature, they become precur­ sors for either monocytes and granulocytes or erythrocytes and mega­ karyocytes, but not both. Some amount of reversibility of this process may exist early in the differentiation cascade, but that is lost beyond a distinct stage in normal physiologic conditions. As cells differentiate, they may also lose proliferative capacity (Fig. 101-3). Mature granulocytes are incapable of proliferation and only increase in number by increased production from precursors. The exceptions to the rule are some tissue-resident macrophages, which appear capable of proliferation, and lymphoid cells. Lymphoid cells retain the capacity to proliferate but have linked their proliferation to the recognition of particular proteins or peptides by specific antigen Mature Cells Precursors Aiolos, PAX-5, AML-1 B Cell IL4 T-Cell Progenitor IKAROS, NOTCH,CBF1 E2A, NOTCH1, GATA3 T Cell IL2 IL7 NOTCH1 Id2, Ets-1 IL7 NK Cell IL15 NK Cell Progenitor Plasmacytoid Dendritic Cell FLT-3 Ligand Monocytoid Dendritic Cell RelB, ICSBP, ld2 FLT-3 Ligand Egn1, Myb Monocyte M-CSF Monocyte Progenitor Granulocyte C/EBPα G-CSF Basophil IL3, SCF Granulocyte Progenitor Mast Cell C/EBPε IL5 Eosinophil Erythrocyte Progenitor GATA1 RBCs EPO EPO Fli-1 AML-1 TPO Platelets TPO Stem Precursor Progenitor Mature Differentiation state More Less Self-renewal ability Proliferation activity Lymphoid exception (memory B and T cells) FIGURE 101-3  Relative function of cells in the hematopoietic hierarchy. The boxes represent distinct functional features of cells in the myeloid (upper box) versus lymphoid (lower box) lineages. receptors on their surface. Like many tissues with short-lived mature cells such as the skin and intestine, blood cell proliferation is largely accomplished by a more immature progenitor population. In general, cells within the highly proliferative progenitor cell compartment are also relatively short-lived, making their way through the differentia­ tion process in a defined molecular program involving the sequential activation of particular sets of genes. For any particular cell type, the differentiation program is difficult to speed up. The time it takes for hematopoietic progenitors to become mature cells is ~10–14 days in humans, evident clinically by the interval between cytotoxic chemo­ therapy and blood count recovery in patients. Although hematopoietic stem cells are generally thought to have the capacity to form all cells of the blood, individual stem cells are hetero­ geneous in their differentiation potential. That is, some stem cells are “biased” to become mature cells of a particular type. In addition, indi­ vidual stem cells may respond differently to proliferation or cell death signals. Therefore, the stem cell population is an aggregate of cells with somewhat distinctive properties that have the collective characteristics ascribed to hematopoietic stem cells. ■ ■SELF-RENEWAL AND CLONAL DYNAMICS Self-renewal is the ability to divide while preserving an undifferentiated state. This stem cell characteristic is generally not seen in progenitor or mature cells where proliferation is coupled with progressive differen­ tiation. Stem cells being able to asymmetrically divide, such that one daughter cell is the product of self-renewal and the other enters into the differentiating progenitor pool, enables the hematopoietic system to have a modestly sized pool of stem cells yet produce seven orders of magnitude greater numbers of mature blood cells each day. Self-renewal has its risks, however. Genetic mutations that occur in a stem cell will durably persist in stem cells because of self-renewal. In contrast, mutations in progenitors will largely be lost as the cells terminally differentiate and die. It is the stem cell then that has greater potential to accumulate genetic mutations, a setting that can lead to cancer. Countering this risk is the small number of stem cells, the radioprotective environment of their bone localized niche, and the relative quiescence of stem cells. Stem cells have distinctive cell cycle regulation. Some are deeply qui­ escent, serving as a deep reserve, whereas others are more proliferative and replenish the short-lived progenitor population. Hematopoietic stem cells are generally cytokine-resistant, remaining dormant even when cytokines drive bone marrow progenitors to proliferation rates measured in hours. Stem cells, in contrast, are thought to divide at far longer intervals, measured in months to years, for the most quiescent cells. This quiescence is difficult to overcome in vitro, limiting the abil­ ity to effectively expand human hematopoietic stem cells. The process may be controlled by particularly high levels of cyclin-dependent kinase inhibitors like p57 or CDKN1c that restrict entry of stem cells into the cell cycle by blocking the G1-S transition. Exogenous signals from the niche also appear to enforce quiescence, including angio­ genin, interleukin 18, and perhaps angiopoietin 1. Individual stem cells may vary in their proliferation and self-renewal features. This can lead to distortions in the representation of any given clone of stem cells, a feature commonly seen with aging and often associated with acquired somatic mutations. Hematopoietic stem cells are estimated to acquire 17 somatic mutations with each year of life based on deep sequencing studies. Some of these appear to provide a fitness advantage to the stem cell as the presence of mutated or “variant” alleles contributing to >1% of blood cells is virtually uniform by age 70. Furthermore, it is estimated that 10–20 such clones exist in individuals by 70, and in aggregate, those clones provide between 30 and 60% of the blood cells. Thus, the diversity of active stem cell clones declines with age with a likely accompanying reduced diversity of functions that each clone provides. Whether this contributes to immune alterations or other aspects of aging is to be determined. However, some expanded clones are associated with “driver” mutations observed in myelodys­ plasia and myeloid leukemias. These clones do have a low frequency of progression to overt neoplastic disease, and at least one of them, an inactivating mutation of TET2, can also increase adverse outcomes from a number of chronic inflammatory conditions. CHAPTER 101 The most common mutations associated with clonal hematopoiesis are of epigenetic regulatory genes. For example, inactivating mutations of the DNA methyl transferase DNMT3a or the dioxygenase involved in DNA demethylation, TET2, are commonly found, as are mutations in ASXL1, a member of the polycomb family of genes whose products alter chromatin structure, a high-order DNA organization that affects transcription. Therefore, epigenetic control appears to be critical for homeostasis of the hematopoietic stem cell pool and constraining the outgrowth of potentially pathogenic stem cell clones. Hematopoietic Stem Cells THE RELATIONSHIP OF STEM CELLS TO CANCER Some cancers have been shown to have a cellular hierarchy similar to normal tissues, with stem-like cells having the capacity to self-renew and differentiate. These stem-like cells can be experimentally trans­ planted into immunodeficient animals and initiate a new cancer. It is hypothesized that these stem-like cells may be the basis for disease relapse after therapy as they have distinctive molecular features from other cells in the cancer that may render them less vulnerable to therapies. Myeloid leukemias have been experimentally shown to be consistent with this model. Focusing therapies on the stem-like cells as opposed to the bulk population of the cancer cells as a means to improve cure rates is an active area of investigation. Given that hematopoietic stem cells can accumulate genetic muta­ tions by virtue of their self-renewal, it is logically appealing to regard them as the likely cell source of leukemias. Experimental testing of this hypothesis has shown that stem cells are more likely to result in malignancy following an oncogenic mutation. However, some more mature populations with less well-defined self-renewal capability can also be transformed to malignancy. Therefore, self-renewal may also be acquired by mutation, and cancer stem-like cells need not have originated in normal stem cells. STEM CELLS AS TARGETS OF GENE THERAPY OR GENE EDITING The hematopoietic stem cell is the ideal cell target for genetic therapies intended to durably change the genome of blood cells. Because stem cells can persist for the lifetime of an individual, genetically modify­ ing them can provide curative therapies for genetic disorders such as hemoglobinopathies or congenital immunodeficiencies. The extensive cell proliferation with limited or no self-renewal among progenitor populations makes them less able to provide durable benefit if they are genetically modified. Therefore, modification of stem cells is criti­ cal and requires integration of the genetic therapy into the host cell’s # 33 - 103 Disorders of Hemoglobin ### 103 Disorders of Hemoglobin ■ ■TREATMENT Treatment of the underlying disorder controls anemia of inflammation, as shown by the effect of anti-IL-6 agents in Castleman’s disease and rheumatoid arthritis. Standard treatment of anemia in CKD is based on ESAs (Chap. 322) with a target hemoglobin established at <11.5 g/dL to avoid cardiovascular complications. Since iron deficiency leads to ESA hyporesponsiveness, iron supplementation is usually required, mostly parenterally, because in advanced CKD high hepcidin levels prevent iron absorption. Intravenous iron is administered at high or refracted doses, ideally to maintain transferrin saturation at 30–40% and ferritin between 200 and 700 μg/L. Iron supplementation may lower the dose of ESA required to maintain the hemoglobin target. An oral alternative to intravenous iron is ferric citrate, which, binding intestinal phosphate, provides iron while reducing phosphate levels. Prolyl hydroxylase inhibitors that stabilize HIF-2α have been approved in some coun­ tries with the aim of replacing with a single oral drug both ESA and iron, since HIF upregulates EPO production as well as duodenal iron absorption. Although these novel antianemic drugs are efficacious, safety concerns still exist for their long-term use. Intravenous iron can be used in cancer-related anemia to reduce the need of transfusions, especially with ferritin <100 μg/L and before elective surgery. ESAs are used in low-risk myelodysplastic syndromes and in patients receiving chemotherapy notably when cancer is deemed uncurable. Intravenous iron supplementation is currently recommended in CHF patients with either ferritin <100 μg/L or transferrin saturation <20% with ferritin of 100–300 μg/L. Nonetheless, there is still some uncertainty as to whether this represents the best definition of iron defi­ ciency in CHF. Novel drugs targeting the hepcidin-ferroportin axis to counteract iron maldistribution are under investigation. Blood transfusions remain the therapeutic option for severe ane­ mia in the ICU, with guidelines increasingly recommending restric­ tive hemoglobin thresholds (7–8 g/dL) for hemodynamically stable patients. Intravenous iron is proposed to minimize the use of trans­ fusions, with some studies reporting improved clinical outcomes, although the risk of infections and hypophosphatemia are of concern in these fragile patients. ANEMIA OF AGING Prevalence of anemia in the elderly is ~10% at the age of 65 years, 25% in people >85 years, and 50% in those affected by multimorbidity, hos­ pitalized, or institutionalized. Anemia is typically mild (hemoglobin 11–12 g/dL) and multifactorial, and its impact is frequently underesti­ mated. Mounting evidence strengthens its negative influence on quality of life, muscle weakness, and the risk of falls and fractures, as well as its independent association with mortality. The adverse effects of anemia are seen in black patients at hemoglobin levels ~1 g/dL lower than in white patients. Approximately one-third of the cases are estimated to be due to nutritional causes, especially iron deficiency; one-third are due to inflammation, including CKD; and one-third remain without a detect­ able origin and are defined “unexplained anemia of aging.” Age-related decline in testosterone levels in males, stem cell exhaustion, and EPO reduction might contribute. Absolute iron deficiency is common, due to poor dietary iron intake, impaired absorption by chronic gastritis, or the use of proton pump inhibitors and blood losses. A gastrointestinal malignancy should always be ruled out in anemic elderly patients, but chronic bleeding may also result from nonmalignant intestinal lesions such as angiodysplasias and the use of antithrombotic drugs for com­ mon disorders such as atrial fibrillation. A recent study has shown that 100 mg of daily aspirin given for primary cardiovascular prevention in elderly subjects was associated with a 20% higher risk of anemia and iron deficiency as compared to placebo. The proposed ferritin cutoff for iron deficiency (45–70 μg/L) is higher than in younger patients. Treatment of iron deficiency may mitigate the negative prognostic implications of anemia. Functional iron deficiency due to overt or subclinical inflam­ mation often contributes, complicating the laboratory diagnosis. Traditionally “bone marrow senescence,” now known as clonal hema­ topoiesis of indeterminate potential (CHIP), is present in >10% of otherwise-healthy individuals aged 70 years and increases sharply to >60% in the eighties. CHIP is associated with a chronic low-grade inflammatory status that worsens anemia and cardiovascular risk. Patients should be followed up for the risk of developing myelodys­ plastic syndromes (Chap. 107). The unexplained anemia of aging is usually characterized by an EPO level that is lower than expected for the degree of anemia. EPO can increase the hemoglobin level, but it is unclear whether that change has an influence on the hospitalization, frailty, and mortality risks associated with the anemia. ■ ■FURTHER READING Camaschella C: Iron deficiency. Blood 133:30, 2019. Cleland JFG et al: Redefining both iron deficiency and anaemia in cardiovascular disease. Eur Heart J 44:1992, 2023. Galy B et al: Mechanisms controlling cellular and systemic iron homeostasis. Nat Rev Mol Cell Biol 25:133, 2024. Ganz T: Anemia of Inflammation. N Engl J Med 381:1148, 2019. GBD 2021 Anaemia Collaborators: Prevalence, years lived with disability, and trends in anaemia burden by severity and cause, 1990-2021: Findings from the Global Burden of Disease Study 2021. Lancet Haematol 10:e713, 2023. Macdougall I: Anaemia in CKD: Treatment standard. Nephrol Dial CHAPTER 103 Transplant 26:770, 2024. Oyedeji CI et al: How I treat anemia in older adults. Blood 143:205, 2024. Pasricha SR et al: Iron deficiency. Lancet 397:233, 2021. Patel KV et al: Haemoglobin concentration and the risk of death in older adults: Differences by race/ethnicity in the NHANES III follow-up. Br J Haematol 145:514, 2009. Van Doren L, Auerbach M: IV iron formulations and use in adults. Disorders of Hemoglobin Hematol Am Soc Hematol Educ Program 1:622, 2023. Weyand AC et al: Prevalence of iron deficiency and iron-deficiency anemia in US females aged 12-21 years, 2003-2020. JAMA 329:2191, 2023. Vijay G. Sankaran, Martin H. Steinberg Disorders of Hemoglobin Hemoglobinopathies result from changes in the amino acid sequence of globin; in thalassemia, synthesis of normal globin is insufficient. Together the disorders of hemoglobin compose the most common Mendelian genetic diseases. In addition, they are responsible for most instances of hemolytic anemia. Sickle cell disease and the hemoglobin E (HbE)–associated syndromes are the most prevalent hemoglobin­ opathies; β and α thalassemia are the most prevalent thalassemias. In addition to these common disorders of hemoglobin, rare globin mutations cause hemoglobin instability, cause increased or decreased affinity of hemoglobin for oxygen (O2), and allow spontaneous oxida­ tion of hemoglobin, reducing its O2 transport. O2 transport can also be reduced by exposure to carbon monoxide (CO) and extrinsic oxidizing agents (Table 103-1). HEMOGLOBIN Easy access to erythrocytes to study hemoglobin structure and func­ tion, reticulocytes to examine hemoglobin biosynthesis, and leukocyte DNA to define the mutations of hemoglobin, with the availability of hematopoietic stem and progenitor cells from blood and bone mar­ row, has placed hemoglobin disorders in the forefront of molecular medicine. The biology of hemoglobin provides the background for understanding the pathophysiology of its many genetic and acquired disorders and approaches to their treatment. TABLE 103-1  Disorders of Hemoglobin I. Hemoglobinopathies—hemoglobin variants with amino acid sequence variants that alter the physical, chemical, or functional properties of hemoglobin A. Common variants with unusual properties 1. HbS—polymerization 2. HbE—reduced biosynthesis 3. HbC—hemoglobin-membrane interaction B. Altered oxygen affinity 1. High affinity—erythrocytosis 2. Low affinity—cyanosis, anemia C. Hemoglobins that oxidize readily 1. Unstable hemoglobins—hemolytic anemia, jaundice 2. M hemoglobins—methemoglobinemia, cyanosis II. Thalassemias—defective biosynthesis of globin chains A. α Thalassemias B. β Thalassemias C. Complex thalassemias III. Hereditary persistence of fetal hemoglobin—persistence of higher than normal levels of HbF into adult life A. Deletions within the HBB cluster—15–30% HbF in heterozygotes, pancellular HbF B. Point mutations in HBG2/1 promoters—5–30% HbF in heterozygotes; PART 4 Oncology and Hematology pancellular or heterocellular HbF IV. Acquired hemoglobinopathies A. Methemoglobin due to toxic exposures B. Sulfhemoglobin due to toxic exposures C. Carboxyhemoglobin D. HbH in erythroleukemia E. Elevated HbF in myelodysplasia ■ ■DEVELOPMENTAL BIOLOGY Successive waves of erythropoiesis direct the synthesis of different hemoglobin molecules that result from sequential activation and silencing of globin genes (Fig. 103-1). Hemoglobin is a tetramer of two pairs of unlike globin polypeptide chains, each containing a tet­ rapyrrole heme group. O2 binds to heme as erythrocytes traverse the lungs and is released in the tissues. Heme is nestled within a protective pocket of each globin subunit. HBB at 11p15.5 HS5 4 3 2 1 LCR HBA at 16pter HbA HS R1-R4 MCS B A FIGURE 103-1  Globin gene clusters and their hemoglobin products during gestation. A. The order of globin genes in the β- and α-globin gene clusters along with their upstream enhancers, the β-globin locus control region (LCR) and α-globin multispecies conserved sequences (MCS), which contain critical regulatory elements. Normal hemoglobin tetramers contain two α-globin chains and two non-α-globin chains. In the example shown, this is adult HbA. The β-globin gene cluster contains an embryonic ε-globin gene (HBE), two nearly identical fetal γ-globin genes (HBG2, HBG1), a major adult β-globin gene (HBB), and a minor adult δ-globin gene (HBD). The α-globin gene cluster contains an embryonic ζ-globin gene (HBZ) and duplicated α-globin genes (HBA2, HBA1) coding for identical proteins. Embryonic hemoglobins include Gower I (ζ2ε2), Gower II (α2ε2), Portland I (ζ2γ2), and Portland II (ζ2β2). Fetal hemoglobin (HbF, α2γ2) production begins at 6–8 weeks’ gestation, peaks during mid-gestation, then falls to <1% of total hemoglobin during the first 6 months of extrauterine life. B. Sites of erythropoiesis and globin synthesized from the yolk sac and the early embryo (months 1–3), the fetus (months 3–9), after delivery (months 9–12), and afterward (adult). ■ ■GLOBIN GENE CLUSTERS Globin is encoded in two nonallelic gene clusters. The β-globin gene cluster is on chromosome 11; the α-globin gene cluster is on chromo­ some 16 (Fig. 103-1). Tetramers of α-like and β-like globins form embryonic, fetal, and adult hemoglobins. Fetal hemoglobin (HbF, α2γ2) production begins at 6–8 weeks’ gestation, peaks during mid-gestation, then falls to <1% of total hemoglobin during the first 6 months of extrauterine life. Adult hemoglobin A (HbA, α2β2) production follows a pattern reciprocal to that of HbF. The hemoglobin composition of normal adults is >95% HbA, ~1% HbF, and 2–3% HbA2 (α2δ2). HbF and HbA2 are not functionally important in normal adults because of their low concentrations. Measuring their levels can provide helpful diagnostic clues for thalassemia and some hemoglobinopathies. Hemo­ globin is subject to posttranslational modifications. Most important clinically is the nonenzymatic glycosylation of HbA forming the adduct HbA1c, which is useful in the management of diabetes mellitus. ■ ■HEMOGLOBIN STRUCTURE All globin polypeptides have similar but not identical primary struc­ tures. α-Globins contain 141 amino acids, and β-like globins have 146 amino acids. This primary structure dictates, according to the constraints of protein folding, the secondary structure of globin into α-helical sections joined by small nonhelical stretches. Each globin chain folds into a tertiary conformation known as the globin fold, whereby charged amino acid residues face the exterior of the molecules while uncharged residues face the hydrophobic interior. The ironcontaining tetrapyrrole heme moiety is protected from oxidation and located between two of the helical segments; O2 loading and unload­ ing occur when heme iron is in its reduced ferrous form. Globin gene mutations affecting critical heme-binding amino acid residues allow iron to be oxidized, forming methemoglobin, which has high O2 affin­ ity and does not release O2 in tissues. Dimers of α- and non-α-globin chains reversibly assemble into the tetrameric quaternary structure. ■ ■HEMOGLOBIN FUNCTION Hemoglobin transports O2 from lungs to tissues and carbon dioxide (CO2) from tissues to lungs. As a nitrate reductase, it releases nitric oxide (NO) from nitrite to promote vasodilation. Oxygen binding is defined by the hemoglobin-O2 dissociation curve. P50 is a point on this sigmoidal curve that indicates the partial pressure of O2 where hemo­ globin is half saturated (Fig. 103-2). Normal P50 is ~26 mmHg; low P50 indicates that hemoglobin has high O2 affinity, decreasing O2 delivery Yolk sac Spleen Bone marrow Liver Globin synthesis (%) HBG1 HBG2 HBB HBE1 HBD Adult pH Less O2 delivered Oxyhemoglobin 2,3-BPG T° Percent saturation of hemoglobin pH More O2 delivered 2,3-BPG P50 T° Deoxyhemoglobin Tissue PO2 (mmHg) FIGURE 103-2  Hemoglobin-oxygen dissociation curve. The P50 is influenced by the binding of 2,3-bisphosphoglycerate (2,3-BPG), a product of glycolysis, in the central cavity of hemoglobin, pH, and temperature. The hemoglobin tetramer can bind up to four molecules of oxygen (O2) in the iron-containing sites of the heme molecules. As O2 is bound, 2,3-BPG and carbon dioxide (CO2) are expelled. Salt bridges are broken, and each of the globin molecules changes its conformation to facilitate O2 binding. O2 release to the tissues is the reverse process, with salt bridges being formed and 2,3-BPG and CO2 bound. Deoxyhemoglobin does not bind O2 efficiently until the cell returns to conditions of higher pH, the most important modulator of O2 affinity (Bohr effect). When acid is produced in the tissues, the dissociation curve shifts to the right, facilitating O2 release and CO2 binding. Alkalosis has the opposite effect, reducing O2 delivery. to tissues; high P50 indicates that hemoglobin has low O2 affinity, releas­ ing more O2 to tissues. The conformation of hemoglobin fully saturated with O2 is known as the R or relaxed state; desaturated hemoglobin is in the T or tense state. The transition between T and R states occurs when two or three O2 molecules are bound. Cooperativity describes the progressively more rapid binding of O2 once the first molecule is bound. Hemoglobin variants that decrease P50 are characterized by isolated erythrocytosis as compensation for hypoxia; variants with increased P50 sometimes are accompanied by cyanosis and anemia as hemoglobin becomes unsaturated and O2 delivery is enhanced. Muta­ tions of residues critical for heme binding, R-T transitions, or tetramer stability cause hemoglobinopathies characterized by hemolytic anemia, methemoglobinemia, erythrocytosis and cyanosis. ■ ■GLOBIN GENE SWITCHING The sequential activation and inactivation of globin genes during development is called “hemoglobin switching.” Transcription factors along with epigenetic elements, such as DNA and histone methyltrans­ ferases and demethylases, interact with enhancers “upstream” of the gene clusters that contact globin gene promoters, silencing the embry­ onic and fetal genes. Developmental factors such as RNA-binding fac­ tors and microRNAs also impact hemoglobin switching. β-Globin Gene Switching  HbF reactivation by drugs and gene therapy is a prime therapeutic goal for treating sickle cell disease and β thalassemia, meriting a discussion of the controls of HbF gene silenc­ ing. An upstream enhancer called the β-globin locus control region (LCR) binds erythroid-specific and ubiquitous transcription factors. The LCR interacts directly with globin gene promoters; transcription factors that silence and activate genes also interact with elements of the globin genes. Competition among the β-like genes for the LCR and autonomous silencing of the embryonic and fetal globin genes depends on transcription factors. Silencing, first of the embryonic gene HBE and then of the two fetal genes, HBG2 and HBG1, favors the interaction of the LCR with HBB allowing its expression (Fig. 103-1). The transcription factors BCL11A (2p16) and ZBTB7A (19p13) are the major repressors of HbF gene expression. BCL11A, a zinc finger protein that represses HbF genes, binds TGACCA motifs, the most important at position –115 in the promoter of each γ-globin gene. ZBTB7A binds 85 nucleotides upstream of these BCL11A binding sites. Mutations in these binding sites abolish the normal silencing of the HbF genes, leading to one type of the benign condition called hereditary persistence of fetal hemoglobin (HPFH). When binding of either BCL11A or ZBTB7A is disrupted, HBG2 and HBG1 are dere­ pressed. BCL11A single nucleotide variants (SNVs) are common and are thought to underlie a large portion of the interindividual variation in HbF levels. Disruption of the BCL11A regulatory elements or the promotor binding sites for BCL11A and other repressive factors by gene editing in patient hematopoietic stem cells using CRISPR/Cas leads to 30–50% HbF with possible “cure” of sickle cell disease and β thalassemia, with the former strategy receiving U.S. Food and Drug Administration (FDA) approval for both conditions. `-Globin Gene Switching  A less complex switch takes place in the α-globin gene cluster. A regulatory locus of four elements termed R1–R4 is present within introns of the gene NPRL3 that is upstream of HBA2. R1–R4 are critical for α-globin gene expression, as dem­ onstrated by natural deletions causing thalassemia. A developmental switch from embryonic ζ- to adult α-globin gene expression occurs at about 6 weeks’ gestation. Modulation of HbF Level and Haplotypes of the a-Globin Gene Cluster  Variations in three quantitative trait loci (QTL), BCL11A, MYB (6q23), and a locus linked to the HBB cluster (11p15), are associated with HbF variation among normal individuals and patients with sickle cell anemia and β thalassemia. The MYB gene is essential for hematopoiesis and erythroid differentiation. MYB inhibits HbF expression directly by activation of KLF1 and other repressors and indirectly through alteration of the kinetics of erythroid differ­ entiation. The third QTL is marked by a common variant 158 nucleo­ tides upstream of the transcription start site of HBG2. Five common haplotypes associated with the HBB cluster have been defined by its SNVs. Sickle cell anemia patients with the Senegal and Arab-Indian HbS gene-associated haplotypes have the common –158 C-T variant in the HBG2 promoter. They have higher HbF levels than patients with Benin, Bantu, and Cameroon haplotypes. When young, they might have a milder clinical course. CHAPTER 103 Disorders of Hemoglobin GENERAL ASPECTS OF HEMOGLOBIN DIAGNOSIS α-Globin gene mutations are expressed in the embryo and fetus and persist throughout life; HbF mutations are expressed in the fetus and in the first months of life, vanishing from notice afterward; δ-globin gene mutations are innocuous and usually not detected; β-globin gene mutations can become clinically apparent after the synthesis of HbF dwindles to stable adult levels. With rare exceptions, all disorders of hemoglobin are autosomal recessive or co-dominant disorders; a family history, usually of ane­ mia, a common feature of most symptomatic hemoglobinopathies and thalassemias, is often present. In addition to pallor and jaundice, sple­ nomegaly is often present. A small number of laboratory tests can con­ firm the diagnosis starting with a complete blood count that includes a reticulocyte count with a careful review of a peripheral blood film. A sustained increase in reticulocyte count indicates the presence of hemolytic anemia. Hemoglobin fractionation by high-performance liquid chromatography (HPLC) or capillary electrophoresis, especially when, in addition to the index case, family members are available for study, is often sufficient to confirm a diagnosis at the level of hemoglo­ bin phenotype. DNA sequencing of the globin genes allows definitive diagnosis; available from excellent reference laboratories, it is a prereq­ uisite for genetic counseling. Sickle cell disease and β thalassemia are chronic hemolytic ane­ mias sharing hemolysis-related complications like venous thrombosis, leg ulcers, and pulmonary hypertension. Differences are that only deoxyHbS polymerizes, while ineffective erythropoiesis is the key pathophysiologic feature of β thalassemia. Both diseases are “cured” by successful allogeneic hematopoietic stem cell transplantation and gene therapy as discussed below. SICKLE CELL DISEASE Sickle cell disease is a clinical and hematologic phenotype caused by an assortment of genotypes (Table 103-2). Sickle cell anemia, defined as homozygosity for the sickle hemoglobin mutation (α2βS 2; glutamic acid [E] 7 valine [V] GAG-GTG), is the most common of these genotypes, followed by HbSC disease or compound heterozygosity for HbS and HbC (α2βC 2; E 7 lysine [K] GAG-AAG) genes. Many different thalas­ semia mutations contribute to the HbS-β thalassemias. Compound heterozygous genotypes are less common than HbS homozygotes. HbS has been described in compound heterozygotes with many other vari­ ant hemoglobins. Few of these genotypes, other than HbSOArab, HbSE, and HbSDPunjab are symptomatic. ■ ■ORIGIN, SPREAD, AND EPIDEMIOLOGY HbS originated in Africa between 7000 and 22,000 years ago, reaching high frequencies because of the increased genetic fitness of heterozy­ gotes under selective pressure from Plasmodium falciparum. HbS gene haplotypes have a loose association with the severity of disease because each haplotype has a different average level of HbF. In some regions of Africa, India, and the Middle East, nearly half the population have sickle cell trait. Nigeria alone has ~150,000 newborns each year with sickle cell anemia, about one-third of the world’s total newborns; most die before age 5. Coerced and free population movement has spread the HbS gene throughout the world. The HbS carrier, or sickle cell trait, prevalence is 2–15% in emigrant populations; ~100,000 patients in the United States have sickle cell disease. In the United States, death in childhood is rare; the median age of death in patients with sickle cell anemia is in the fifth or sixth decade. PART 4 Oncology and Hematology ■ ■PATHOPHYSIOLOGY Pathophysiologic features of sickle cell disease are summarized in Fig. 103-3. HbS is physiologically like HbA in most respects except it polymerizes when deoxygenated. Contacts between one of the TABLE 103-2  Common Sickle Hemoglobinopathies GENOTYPE CLINICAL ABNORMALITIES Sickle cell trait (HbAS) 8% of African Americans; hematuria, papillary necrosis, hyposthenuria, increased incidence of chronic kidney disease; 2–4 times increased VTE risk;? stroke; splenic infarction at altitude; rhabdomyolysis Sickle cell anemia (HbSS) Vasoocclusion related: pain, acute chest syndrome, osteonecrosis, splenic infarction Hemolysis related: stroke, pulmonary and systemic vasculopathy, nephropathy, leg ulceration gallstones, priapism HbS-β0 thalassemia Rate of complications similar to HbSS 80–100 (8–11)/60–85 HbS: >75 HbF: 2–15 HbA2: 5–6 HbS-β+ thalassemia Rate of complications about half the rate of HbSS depending on percent HbA 100–140 (10–14)/70–80 HbS: 60–90 HbA: 5–40 HbF: 1–10 HbA2: 5–6 Hemoglobin SC disease (HbSC) Nearly asymptomatic to disease as severe as HbSS; about half the rate of complications as HbSS. Increased risk of retinopathy HbSE Resembles clinically HbS-β+ thalassemia; symptoms delayed; often Asian/Indian ancestry HbSS-α thalassemia Present in 30% of HbSS; phenocopies HbS-β0 thalassemia because of microcytosis and high HbA2; like HbSS but with fewer strokes and leg ulcers and less pulmonary vascular and renal disease Note: Laboratory values are averages in untreated adults. Abbreviation: VTE, venous thromboembolism. β7 valine residues of deoxyHbS and specific amino acid residues of β- and α-globin culminate in fascicles of hemoglobin that injure the sickle erythrocyte. A delay occurs between the initiation of polym­ erization and the accumulation of sufficient polymer to damage the cell. It is unclear how much polymer is needed for cell injury, but polymer leads directly and indirectly to the multiple abnormalities of the sickle erythrocyte that generate the pathophysiology of disease. Prominent among these abnormalities are HbS polymer penetration of the membrane causing vesiculation with membrane microparticle release; increased activity of the Gardos, K/CL cotransport, and Psickle channels that dehydrate the cell, increasing mean corpuscular sickle hemoglobin concentration (MC[HbS]C), reducing cellular deform­ ability, and increasing the polymerization potential of HbS; transloca­ tion of amino phospholipids such as phosphatidylserine to the outer leaflet of the membrane; and oxidation of erythrocyte contents. These and other abnormalities lead to the formation of irreversibly sickled cells (ISCs), which are sickle erythrocytes that are forever deformed because of permanent membrane damage regardless of whether HbS remains polymerized. Damaged sickle erythrocytes are responsible for initiating the vasoocclusive, hemolytic, and inflammatory features of the disease shown in Fig. 103-3. ■ ■DIAGNOSIS Although sickle cell disease can appear in any ethnic group, most often it is present in people of African, Middle Eastern, Mediterranean, and Indian descent. The chief presenting symptom is pain. This might be an arthritis-like hand-foot syndrome in young children or the typical acute painful episode in older children and adults. In HbSC disease and HbS-β+ thalassemia, acute vasoocclusive episodes occur at about half the rate as in sickle cell anemia while complications develop later; rarely, patients with these genotypes are asymptomatic. The key elements of laboratory diagnosis are outlined in Table 103-2 showing typical hematologic findings and hemoglobin fractions. Figure 103-4 displays HPLC profiles and blood films in typical patients with sickle cell trait, sickle cell anemia, and HbSC disease. Clinical and basic laboratory diagnosis is sufficient for general management and counseling; genetic counseling and family planning usually require DNA-based diagnosis. HEMOGLOBIN LEVEL, g/L (g/dL)/MCV, fL HEMOGLOBIN FRACTIONS (%) Normal HbA: 60–70 HbS: 30–40 Percent HbS dependent on presence or absence of α thalassemia 70–100 (7–10)/80–100 HbS: >75 HbF: 2–25 HbA2: 3–4 100–140 (10–14)/70–100 HbS: 50 HbC: 50 90–130 (9–13)/65–75 HbS: 65 HbE: 35 HbF: 1–5 80–100 (8–11)/60–85 HbS: >75 HbF: 2–15 HbA2: 4–5 HbS polymer Triplet codon T 7 Glu Valine residue GAG HbS solution HbS polymer N Oxygenated Deoxygenated Hemolysis HbS cell Cell heterogeneity FIGURE 103-3  Pathophysiology of sickle cell disease. HbS is in solution when oxygenated but reversibly polymerizes when deoxygenated. Polymerization is dependent on the 30th power of hemoglobin concentration. In the sickle cell, this means that small changes in hemoglobin concentration or cell hydration can have large effects on polymerization. Polymerization begins seconds to minutes following deoxygenation. Erythrocyte deformation, or sickling, is initially reversible, but after an undetermined number of cell sickling events, the cell becomes irreversibly deformed. These are known as irreversibly sickled cells (ISCs). Their membrane is permanently damaged, although depending on their oxygen (O2) content, HbS could be in solution. Sickle erythrocytes lead to the clinical and laboratory phenotypes of disease. Sickle cells interact with endothelial cells and other blood cells, occluding flow in small and sometimes large vessels and causing the many complications thought to be a result of vasoocclusion. Sickle cells also live <20 days (normal ~120 days) hemolyzing intra- and extravascularly. Intravascular hemolysis depletes haptoglobin and hemopexin while liberating heme, arginase, and other danger-associated molecular patterns (DAMPs) into the blood. This scavenges nitric oxide (NO), activates platelets and endothelium, reduces antioxidant activity, causes vasoconstriction, and is proinflammatory. ■ ■COMPLICATIONS Complications of sickle cell disease can be grouped into those that likely are a consequence of the related entities of sickle vasoocclusion and those due to intravascular hemolysis (Fig. 103-3). Complications associated with vasoocclusion seem to respond best to induction of HbF. Some complications of disease are presented in Table 103-3. Acute Painful Episodes  Characterized by unprovoked severe pain in extremities or the torso that is often symmetrical and stereo­ typical for each patient and that usually requires treatment with strong opioids in the emergency department, acute painful episodes are the most common acute events in sickle cell disease. They are the chief cause of concern for patients, most of whom have them at some time in their life. Their frequency varies; most patients have one to two episodes a year; some rarely have them; others are hardly ever without them. Acute painful episodes last days to weeks. Pain in sickle cell dis­ ease can also be chronic from osteonecrosis, osteoporosis, or leg ulcers. Chronic and acute pain can overlap. Pain can also be induced by the opioids. Most of the time, patients have some degree of pain that does not reach the intensity of the acute episode. This can be treated with oral opioids dispensed monthly. No diagnostic test can confirm or refute the presence of an acute pain episode whose cause is uncommonly identified. Physical examination is not often useful diagnostically. Some patients will have pain on pressure over an affected area, perhaps accompanied by swelling; mild fever is common. Often a 1–2 g/dL decrease in hemoglobin level and a modest increase in the leukocyte count are noted. The presence of ISCs and Vasoocclusion R RBC ISC EC NO NO synthase NO – CHAPTER 103 Arginine NO Arginase Ornithine Citruline Disorders of Hemoglobin the reticulocyte count are of no diagnostic value. Drastic decreases in hemoglobin and platelet levels with more extreme leukocytosis can por­ tend development of severe acute chest syndrome or multiorgan failure. Some patients die suddenly shortly after admission for an acute painful episode. The cause of this sudden unexpected death is usually unknown; among the possibilities are arrhythmias and pulmonary embolism. Admitting patients to monitored beds or using continuous pulse oximetry for the first 48–72 h of hospitalization might prevent some of these deaths and help identify early acute chest syndrome that follows within 72 h in about a quarter of admissions for acute pain. After searching for possible precipitants such as infection or dehydra­ tion and treating these appropriately, the foundation of treatment is the proper dosing of opioid analgesics. By the time a patient presents at the emergency department or clinic requesting treatment, they have usually tried nonsteroidal anti-inflammatory drugs (NSAIDs) and oral opioids. In most patients, relief of pain requires intravenous opioids. Many patients are opioid tolerant, requiring higher than usual doses for satisfactory relief. Dosing should not be on an “as-needed” schedule; patient-controlled analgesia or frequent fixed doses of opioids with res­ cue doses for breakthrough pain are the preferred means of treatment, with frequent assessments to ensure pain relief without excessive seda­ tion. Adjunctive treatment includes incentive spirometry to forestall pulmonary complications, maintaining hydration with half-normal saline with care not to overhydrate, prophylaxis for thromboembolism, and antihistamines and laxatives to counter expected side effects of opioids. Unless hypoxia is present, supplemental O2 is unnecessary. NSAIDs have little value in patients receiving intravenous opioids. 45.0 45.0 37.5 37.5 30.0 30.0 15.0 % 22.5 22.5 E 2.14 A2 3.64 15.0 1.20 1.36 1.67 7.5 7.5 4.51 2.33 0.0 0.0 HbF HbS HbA HbA2 HbS PART 4 Oncology and Hematology FIGURE 103-4  Diagnosis of sickle cell disease. A. From left to right, high-performance liquid chromatography separation in sickle cell trait, sickle cell anemia, and HbSC disease. Beneath each chromatogram, the individual protein peaks are identified. B. Left: Dense, elongated, and pointed cells are the irreversibly sickled cells characteristic of the sickle cell anemia and sickle cell-β0 thalassemia. Target cells and nucleated red cells are also present. Right: Target cells, cells with squared ends of HbC crystals, cells folded like tacos, and contracted microspherocytes are typical of HbSC disease. (Source: B [right]: Reproduced with permission from American Society of Hematology.) TABLE 103-3  Complications of Sickle Cell Disease COMPLICATION INCIDENCE, DIAGNOSIS, AND FEATURES TREATMENT Priapism ~30% of males; can be episodic and short duration (stuttering); severe episodes can cause impotence; associated with markers of hemolysis Stroke and silent infarction 10–15% of all cases; infarction in early childhood into adulthood; hemorrhagic in adults; neurocognitive abnormalities in adults even without apparent stroke; associated with markers of hemolysis Gallstones/surgery ~40% of patients; bilirubin levels and stones related to polymorphisms of UGT1A; in surgery requiring general anesthesia, simple preoperative transfusion to a hemoglobin of 10 g/dL is recommended Hepatic disease >80% of patients have hepatomegaly; intrahepatic cholestasis can have bilirubin ~100 mg/dL; viral hepatitis, iron overload, RBC sequestration, extrahepatic cholestasis also contribute Nephropathy ~30% of adults age >30 years; hyperfiltration in children, renal failure in adults; early albuminuria, later nephrotic-range proteinuria; associated with markers of hemolysis Lung/pulmonary hypertension Restrictive disease; asthma common; 5–10% have pulmonary hypertension by right heart catheterization; 30% have increased TRV that portends poor prognosis; associated with markers of hemolysis Retinopathy 30% in HbSC disease, 3% in HbSSa; develops in peripheral retina; vitreous hemorrhage and retinal detachment can cause blindness Acute anemic episodes B19 parvovirus infection, folic acid deficiency, splenic sequestration, delayed hemolytic transfusion reaction with destruction of transfused and sometimes autologous red cells Multiorgan failure Can accompany severe acute chest syndrome; often confused with sepsis and can coexist with sepsis; CNS liver, muscle, lung, kidney affected Pregnancy Screening both partners for hemoglobin disorders with risk counseling is critical component of family planning aSickle cell anemia (HbSS). Abbreviations: ACE, angiotensin-converting enzyme; CNS, central nervous system; ICU, intensive care unit; NSAIDs, nonsteroidal anti-inflammatory drugs; RBC, red blood cell; TRV, tricuspid regurgitant jet velocity. 45.0 37.5 30.0 22.5 3.65 15.0 3.61 2.20 2.33 F 1.14 7.5 2.43 A2 4.51 4.67 A2 5.17 0.0 HbS HbC Many therapies including α-adrenergic agonists, stilbesterol; consult urology for treatment, which is time-critical Transcranial Doppler screening in children ages 2–16; transfusion for at-risk patients; hydroxyurea If asymptomatic, usually let be; otherwise, laparoscopic cholecystectomy Exchange transfusion for intrahepatic cholestasis; transplant for end-stage liver failure Screen for microalbuminuria by age 10 years; avoid NSAIDs; use ACE inhibitors or receptor antagonists for albuminuria; erythropoietin for symptomatic anemia; dialysis or transplant for renal failure Consult expert pulmonologist; screen yearly by echocardiography measurement of TRV Screen annually starting at age 10 tears with fluorescein angiography; laser photocoagulation for proliferative disease RBC transfusion if symptomatic; splenectomy if more than 1 or 2 episodes of sequestration; anti-parvovirus IgM positive in acute infection, IgG in past infection Exchange transfusion, ICU support All pregnancies are “high risk”; transfuse if sickle cell events increase, if previous miscarriage, multiple fetuses Acute Chest Syndrome  This pneumonia-like illness is the second most frequent acute sickle cell–related event. It occurs in >50% of patients, often more than once. Acute chest syndrome can be mild, especially in children, in whom it can result from viral infection, or devastating, where multiple lobes of the lung are affected with severe hypoxia, multiorgan failure, and death. Chest pain, cough, fever, and hypoxia and a pulmonary infiltrate on chest x-ray are the major diag­ nostic criteria. The etiology includes in situ thrombosis, emboli, any type of infection, and postoperative hypoventilation. Management in adults is dictated by the severity of the episode and the need for supple­ mental oxygen. Patients who are hypoxic and febrile can be admitted directly to the intensive care unit. Antibiotics are almost always used in these patients even though a causative bacterium is not often cultured. Supplemental O2 is given for an O2 saturation <95%. Overhydration and excessive opioids can compound dyspnea and hypoxia. Hypoxic patients who are febrile with leukocytosis with more than a trivial infiltrate on x-ray are transfused. In the severely ill patient, exchange transfusion, if possible, is the preferred modality. However, if transfu­ sion of the severely ill patient is indicated and hours are needed to arrange red cell exchange, simple or top-up transfusion should be started first. Simple transfusions also suffice for less severely affected patients. Most patients survive acute chest syndrome, but in the most severe cases, often caused by embolization of necrotic bone marrow, death can be rapid even with prompt and proper treatment. Thrombo­ cytopenia, leukocyte counts >20,000/dL, and rapidly developing acute anemia often portend severe acute chest syndrome with its possibility of acute respiratory distress syndrome and multiorgan failure. Asthma is very common in patients with sickle cell disease. Some adults have chronic lung disease with reduced diffusing capacity for CO that could be a sequela of acute chest syndrome. Osteonecrosis  This painful and sometimes crippling complica­ tion that most often affects hips bilaterally occurs in about half of all patients with sickle cell anemia and is also common in HbSC disease; shoulders are less often affected. Beginning with chronic pain that can become severe, loss of function, especially in the hips, is often the final stage. Magnetic resonance imaging (MRI) can detect the earliest stages, whereas x-ray is less sensitive. Physical therapy and NSAIDs provide some initial relief; oral opioids are sometimes required. Joint replacement can restore lost mobility while relieving pain. Life span of prosthetic joints is finite, so surgery should be delayed as long as mobil­ ity is satisfactory and pain tolerable. Leg Ulcers  The incidence of leg ulcers is highly dependent on geography and hemoglobin genotype. They are far less common in HbSC disease and HbS-β+ thalassemia than in sickle cell anemia and HbS-β0 thalassemia. In temperate climates, 10–20% of patients are affected; tropical and subtropical areas have an incidence rate up to 75%; ulcers rarely occur in patients from the Middle East. Leg ulcers can be small and superficial or deep and encompass most of the lower leg. They can be extraordinarily painful. Long-standing, recurrent large ulcers are difficult to treat. Wet-to-dry dressings and Unna boots are reasonable choices for initial treatment. ■ ■SICKLE CELL TRAIT (CARRIERS, OR SIMPLE HETEROZYGOSITY FOR THE HBS GENE) Carriers of sickle cell trait outnumber patients with the disease by 25 to 1. Although testing for sickle cell disease is part of most perinatal cord blood screening programs, counseling and follow-up of detected carriers are imperfect, so adolescents and adults can be unaware they carry sickle cell trait. Counseling carriers about the complications of sickle cell trait and their likelihood of having offspring with sickle cell disease is essential. Carriers should be counseled prior to participation in sports because of the risk, albeit small, of sudden death from heatrelated exertional rhabdomyolysis. Optimal hydration before and dur­ ing exercise can prevent most episodes of heat-related illness. Usually a benign condition with a normal life expectancy, some complications are shown in Table 103-2. ■ ■TREATMENT, SCREENING, COUNSELING, AND ANTENATAL DIAGNOSIS Patients should, if possible, be referred to a sickle cell center for initial consultation, institution of therapy, and follow-up. Cooperation among primary care providers, hematologists, and other specialists provides the best preventive care and management of complications. The fre­ quency at which a patient is seen depends on their therapeutic regimen and complications. Remarkable changes in the treatment landscape have occurred with the promise of even greater benefits from new curative approaches. The following discussion focuses on treatment to prevent the complications of disease. Hydroxyurea  Hydroxyurea is the standard of care for all patients with sickle cell anemia and HbS-β0 thalassemia regardless of symptoms. Although in some symptomatic patients with HbSC disease, its benefits in this genotype are understudied. The major mechanism of action of hydroxyurea is to induce high levels of HbF. Hydroxyurea increases HbF unevenly among red cells (heterocellularly), so some cells have greater protection from HbS polymerization than others. When started in adults, where the average baseline HbF is ~5%, HbF increases to ~10%. Nevertheless, pain and acute chest syndrome are reduced by about half, hemoglobin concentration increases by ~1 g/dL, and after 17.5 years of follow-up, mortality was reduced by 49%. In contrast, all young children respond robustly to hydroxyurea. When started at <1 year of age at a dose of ~27 mg/kg, HbF levels were 33.3 ± 9.1% and hemoglobin concentration was 10.1 ± 1.3 g/dL. Acute events were markedly reduced with little toxicity. Based on these and other studies in high- and low-resource countries, unless there is a contraindication, hydroxyurea should be given to all infants with sickle cell anemia and HbS-β0 thalassemia starting at 9 months of age at a dose of ~20 mg/kg and titrated to the maximal tolerated dose based on neutrophil and platelet counts. CHAPTER 103 Disorders of Hemoglobin Voxelotor  Voxelotor increases the affinity of the hemoglobin mol­ ecule for O2. At a dose of 1500 mg daily, hemoglobin concentration increased ~1 g/dL in 59% of patients with a reduction in the biomark­ ers of hemolysis. Its effects on acute vasoocclusive events are unclear. Many questions remain about the long-term effects of voxelotor. Less hemolysis reduces the propensity for stroke, nephropathy, pulmonary hypertension, leg ulcers, and priapism. Will voxelotor be accompanied by these long-term benefits? Could the high O2 affinity of a modi­ fied hemoglobin be harmful for some patients? The answers to these important questions require further study. Crizanlizumab  Downstream effects of HbS polymerization include adhesive interactions among endothelial cells, leukocytes, platelets, and erythrocytes. P-selectin is one molecule involved in these interactions; blocking selectins prevents sickle cell–endothelial cell adhesion. Crizanlizumab, a P-selectin-blocking monoclonal antibody given intravenously every month, reduced acute painful episodes by ~45%. Hemolysis was unaffected. A follow-up trial failed to replicate the results of the rigorous study that led to FDA approval. l-Glutamine  The mechanism of action of this agent, presumed to be the reduction of oxidative stress in sickle erythrocytes, is unsettled. A phase 3 placebo-controlled trial showed that l-glutamine was asso­ ciated with a 25% reduction in painful episodes and 33% reduction in hospitalization. There is little consensus regarding how these recently approved drugs should be integrated into treatment with hydroxyurea. The effects of voxelotor and crizanlizumab appear to be additive to those of hydroxyurea. Voxelotor can be added to hydroxyurea if the benefits of hydroxyurea alone are insufficient, as they are in most adults. If both hydroxyurea and voxelotor are taken at effective doses and acute vasoocclusive complications continue, crizanlizumab might then be added. The dropout rates in the crizanlizumab and l-glutamine trials were ~35%, so adherence to these therapeutics could be problematic. Transfusion  Transfusions are overutilized and underutilized. Major indications for transfusion include severe symptomatic anemia; treatment and prevention of stroke; increasing hemoglobin level to ~10 g/dL before surgery requiring general anesthesia; and severe acute chest syndrome. Sometimes transfusions are given during pregnancy when there is a history of complications or fetal loss. Transfusions should usually be avoided in acute pain episodes and for repair of stable chronic anemia. Automated red cell exchange transfusion is preferred in acute stroke, severe acute chest syndrome, or multiorgan failure or when chronic transfusions are planned. Expert guidelines recom­ mended extended red cell antigen profiling, if possible, before the first transfusion and antigen matching for Rh (C, E or C/c, E/e) and K anti­ gens in addition to ABO/RhD. Complications of transfusion include hyperviscosity, alloimmunization (which occurred in 18.6% of patients transfused between 1979 and 1984 and 27.3% of patients transfused between 2001 and 2011), iron overload, and delayed hemolytic transfu­ sion reactions with hyperhemolysis. Stem Cell Transplantation  Given the excellent results of human leukocyte antigen (HLA)–identical related donor transplants, which have an event-free survival of >95%, this option might be extended to all patients with a suitable donor. Unfortunately, only 15% of patients have a fully matched donor. New approaches to haploidentical trans­ plants are improving event-free survival in these patients. PART 4 Oncology and Hematology Gene Therapy  Two forms of ex vivo gene therapy are approved for sickle cell disease. Both use mobilized autologous CD34+ stem cells and increase levels of a hemoglobin that inhibits HbS polymerization. In one approach, an HbA gene containing the βT87Q mutation respon­ sible for the antipolymerization effects of HbF is introduced into stem cells via a lentiviral vector. In the second, the major enhancer of the HbF repressor, BCL11A, is disrupted using CRISPR/Cas9 gene editing. In both approaches, following myeloablative conditioning, engineered cells are reinfused and engraft. Both treatments have resulted in near pancellular distribution of 30–50% HbF or HbAT87Q, reduced hemoly­ sis, and total hemoglobin concentrations of >12 g/dL, with nearly total prevention of acute vasoocclusive events. Long-term safety and cure rate will take many more years of follow-up to establish. Preventive Measures and Screening  Cord blood screening for sickle cell disease is done in many countries and all 50 states. Affected patients are then directed to clinics that can initiate early preventive care. In childhood, transcranial Doppler screening beginning at age 2 years and repeated annually until age 16 years, prophylactic penicillin (125 mg for children younger than 3 years; 250 mg for children 3 years and older) twice daily until age 5 years, and vaccination with pneumo­ coccal vaccines are the main measures to prevent stroke and invasive pneumococcal infection. Folic acid, 1 mg daily, is given to prevent megaloblastic erythropoiesis; it is probably unnecessary in people with nutritious diets. All women planning pregnancy should be screened for disorders of hemoglobin by blood counts, erythrocyte indices, and HPLC analysis of hemoglobin. Individuals with HbS or β thalassemia trait should have their partners tested. Only then is it possible to know the risks of a fetus having sickle cell disease (Table 103-2). Antenatal diagnosis using chorionic villus sampling or cell free DNA testing is widely available. THALASSEMIA Thalassemia is caused by reduced accumulation of either α- or β-globin chains causing a relative excess of the unaffected chain. Unbalanced globin synthesis is the hallmark of thalassemia and the proximate cause of its pathophysiology; unpaired globin chains damage the developing erythroblast. Like the HbS mutation and many other red cell traits, thalassemia reached polymorphic levels in tropical and subtropical populations because heterozygotes are protected from severe forms of P. falciparum infection. Estimates are that 1–5% of the world’s popula­ tion carries a thalassemia mutation; in some locales, most people have a thalassemia mutation. These mutations can affect any globin gene, but clinically, β and α thalassemia are the most important. With nearly 500 unique thalassemia-causing mutations (www.globin.bx.psu.edu) that can interact with each other and with hemoglobinopathies, thal­ assemia syndromes are remarkably diverse. Where resources permit and the mutation is known, genetic counseling can be provided and antenatal diagnosis is possible. HbE (β27 glu-lys) is a common variant whose biosynthesis is reduced because the site of the mutation alters its mRNA processing. Its reduced biosynthesis leads to a deficit of βE-globin chains and features of β thal­ assemia. Hemoglobin Constant Spring is caused by a mutation of the termination codon of HBA2 that leads to the synthesis of an elongated α-globin chain that is unstable and suboptimally synthesized. This variant therefore behaves as an α thalassemia variant. a THALASSEMIA ■ ■EPIDEMIOLOGY Once known as Mediterranean anemia, because of the concentration of cases in Italy, Greece, and other countries bordering the Mediter­ ranean Sea, or as Cooley’s anemia after the physician first describ­ ing cases, β thalassemia is common in most areas of the world where malaria was endemic, including the Mediterranean region, Asia, and the Middle East. Effective programs of screening, counseling, and antenatal diagnosis have reduced the birth of new cases in a number of regions. About 40,000 β thalassemia patients are born yearly. In the United States, there are ~1000 cases of severe β thalassemia. ■ ■CLASSIFICATION β0 Thalassemia mutations totally prevent the accumulation of any globin from the affected gene; β+ thalassemia mutations cause minor or moderate reductions in β-globin synthesis. β Thalassemia major and β thalassemia intermedia are now categorized as transfusiondependent and non-transfusion-dependent based on the number and frequency of transfusions required to sustain a good quality of life. Pathophysiology  Single nucleotide changes are the most common β thalassemia mutations, but gene deletions also occur. A partial listing of the classes of mutations causing β thalassemia include mutations in the promoter elements affecting gene transcription causing mild and sometimes silent β+ thalassemia; mutations in the junctions between exons and introns that affect mRNA processing causing β0 and β+ thal­ assemia; introduction of alternative splice sites into introns or exons usually causing β+ thalassemia; 3′ end-processing sequence mutations preventing RNA polyadenylation leading to mild or silent β+ thalas­ semia; mutations preventing initiation of translation causing β0 thal­ assemia; and introduction of stop codons that prematurely terminate translation (nonsense mutations) producing reading frameshifts and resulting in truncated globin mRNA and β0 thalassemia. In addition, rare causes of β thalassemia have been identified that are unlinked from the β globin locus and caused by mutations in general transcrip­ tion regulators, such as SUPT5H and TFIIH, or erythroid transcription factors like GATA1. In β thalassemia, the deficit in β-globin chain synthesis allows α-globin chains to accumulate in excess. Without a non-α-globin chain partner in dimer and tetramer formation, unpaired α-globin chains are unstable, cannot form a tetramer, and precipitate within the developing erythroblast, causing membrane lipid oxidation and dam­ age. The predominant cause of anemia is intramedullary destruction of erythroid precursors, known as ineffective erythropoiesis. Reduced deformability and phosphatidyl serine exposure also cause extra- and intravascular hemolysis of those erythrocytes that gain entrance into the circulation. In poorly treated β thalassemia, severe anemia leads to bone marrow expansion; hepatosplenomegaly; iron accumulation in liver, heart, and endocrine organs; pulmonary hypertension; and thromboembolic disease. Frightening pictures of children with severe β thalassemia permeate the literature. These examples of near-terminal disease should be rel­ egated to history because treatment with transfusion and iron chelation can prevent their occurrence, hematopoietic stem cell transplantation can “cure” patients who have suitable donors, and efficacious gene therapies are now approved. ■ ■DIAGNOSIS Heterozygous β thalassemia, also known as β thalassemia trait and β thalassemia minor, has mild or no anemia but microcytic/hypochro­ mic erythrocytes with minimal or no increase in reticulocyte count. After recognizing these hematologic abnormalities and excluding iron deficiency, finding an elevated level of HbA2 and perhaps HbF by HPLC is sufficient to establish this diagnosis. The hematologic char­ acteristics of this heterozygous carrier state are listed in Table 103-4. Sometimes, the spleen is enlarged. Before genetic counseling and ante­ natal diagnosis are considered after carrier identification by red cell indices and quantitation of HbA2, the thalassemia-causing mutation should be identified. Sequencing is the key to preventing homozygotes or compound heterozygotes with transfusion-dependent thalassemia. The more severe forms of β thalassemia are hemolytic anemias with hypochromia, microcytosis, reticulocytosis, marked anisocytosis, and poikilocytosis with variable numbers of circulating nucleated red cells (Fig. 103-5). ■ ■COMPLICATIONS Complications of severe β thalassemia are many. They are a consequence of chronic hemolytic anemia, chronic transfusion, and iron loading. Increased iron absorption is especially common in non-transfusiondependent thalassemia. Most complications, listed in Table 103-5, develop because of either inadequate blood transfusion and/or poor iron chelation and iron loading. Even when chelation is optimized, some complications attributable to iron toxicity will develop. Many complications have complex and multifactorial etiologies. Iron stores are estimated by serum ferritin levels; MRI is the most widespread means of noninvasively measuring iron accumulation in liver and heart. ■ ■MANAGEMENT, SCREENING, COUNSELING, AND ANTENATAL DIAGNOSIS Heterozygote screening and counseling couples at risk for affected fetuses, with antenatal diagnosis, if needed, is an effective preven­ tive approach. Severe thalassemia should be dealt with in specialized centers where these and other services are available and managed by a team led by a hematologist experienced with this disease with help from endocrinologists, cardiologists, transfusion medicine specialists, and social services. Transfusion and Iron Chelation  Transfusion every 2–4 weeks with a goal pretransfusion hemoglobin concentration of 9–10.5 g/dL TABLE 103-4  β Thalassemias HEMOGLOBIN (g/dL)/MCV (fL) HEMOGLOBIN FRACTIONS (%) CLINICAL FEATURES CLASSIFICATION β-Thalassemia trait 100–140 (10–14)/60–80 HbA: 94 HbF:1–2 HbA2: 4–6 Non-transfusion-dependent β thalassemia (thalassemia intermedia) 70–120 (7–12)/65–80 HbA: 60–90 HbF: 10–40 HbA2: 4–6 20–40 (2–4)/50–80 HbA: 0–5 HbF: 90–100 HbA2: 2–5 Transfusion-dependent β thalassemia (Thalassemia major) HbE-β thalassemia 50–80 (5–8)/60–70 HbE: 50–70 HbF: 30–50 110–120 (11–12)/65–75 HbA: 70 HbF: 7–13 HbA2: 2 δβ Thalassemia and Hb Lepore Gene deletion hereditary persistence of fetal hemoglobin (HPFH) 120–140 (12–14)/75–85 HbA: 70 HbF: 15–30 HbA2: 2 Note: Laboratory results are averages in adults. FIGURE 103-5  α Thalassemia intermedia. Target cells and marked variation in cell size and shape but with general hypochromia and microcytosis characterize the blood film. A lymphocyte is shown for size comparison. to suppress ineffective erythropoiesis, coupled with iron chelation to prevent the accumulation of excess toxic iron that accompanies trans­ fusion, has prevented the development of cardiomyopathy and endo­ crinopathies while extending life to at least 50 years. When to begin transfusions, whether partial exchange transfusion is preferable to simple transfusion, and the choice of blood product require consulta­ tion with experts. To be effective, transfusions and iron chelation must be started early, be uninterrupted, and continue lifelong. Older patients who did not have the advantage of effective chelation are more likely to develop multiple disease-related morbidities such as osteoporosis, endocrinopathies, liver disease, and renal failure. Two orally effective chelating agents, deferasirox and deferiprone, and one intravenous chelator, deferoxamine, are available. CHAPTER 103 Disorders of Hemoglobin Improving Ineffective Erythropoiesis  Luspatercept is a fusion protein containing the extracellular domain of human activin type IIB receptor and the Fc domain of human IgG. By binding transforming growth factor β superfamily ligands and reducing Smad2/3 signaling, luspatercept enhances late-stage erythropoiesis. Given subcutaneously, 1 mg/kg every 3 weeks, it was associated with a 33% reduction in trans­ fusion requirements. Heterozygosity for β+ or β0 thalassemia mutations; “silent” carriers can have normal HbA2 and red cell indices. Defined by infrequent or no transfusion requirement; caused by many different genotypes including homozygosity for “mild” β+ mutations, combinations of β and α thalassemia, homozygous β thalassemia with high HbF-producing capacity, and many others. Iron loading, thromboembolic disease, and pulmonary hypertension are major clinical events. Caused by many different genotypes including homozygosity and compound heterozygosity for β0 and β+ mutations, combinations of β and α thalassemia; transplantation curative; iron chelation required. Common in Southeast Asian populations; in some parts of the world, the most prevalent severe thalassemia; in HbE-β0 thalassemia, only HbE and HbF are found; in HbE-β+ thalassemia, HbA is present. Transfusion dependence depends in part on the thalassemia mutation. Rare; deletions removing the δ- and β-globin genes cause δβ thalassemia; Lepore hemoglobins are fusion globin chains; values are for heterozygotes; homozygotes have 100% HbF with hemoglobin 10–11 g/dL. Rare; large deletions removing the δ- and β-globin genes; values are for heterozygotes; homozygotes, who are asymptomatic, have 100% HbF without anemia. TABLE 103-5  Complications of a Thalassemia COMPLICATION INCIDENCE, DIAGNOSIS, AND FEATURES Growth retardation Most often a feature of delayed or inadequate transfusions but can occur in well-transfused children. Delayed puberty; secondary amenorrhea 50% and 25%, respectively. Splenomegaly Can trap 1–40% of red blood cell volume; increases plasma volume, worsening heart failure. Splenectomy indicated when transfusion requirement to maintain ideal hemoglobin increases. Prophylactic penicillin after splenectomy. Heart Due to chronic anemia, heightened sensitivity to iron toxicity, thromboembolic pulmonary hypertension, other causes. Progresses through stages to congestive failure and arrhythmias. Assessed by T2* on magnetic resonance imaging (MRI). The available chelating agents might have differential effects on different measure of cardiac function and can be used in combination. Leg ulcers Common in thalassemia intermedia. Hepatic disease Fibrosis progressing to cirrhosis is related to hepatic iron concentration that can be monitored by MRI. Hepatitis also plays a role. Lung disease/ pulmonary hypertension Fibrosis, chronic thromboembolic disease, restrictive pathophysiology, intravascular hemolysis, and reduced nitric oxide bioavailability. PART 4 Oncology and Hematology Thromboembolism Multifactorial etiology, including platelet activation, red cell–endothelial interactions, thrombocytosis, endothelial activation, splenectomy. Endocrinopathies Diabetes, hypothyroidism, hypoparathyroidism, adrenal insufficiency; hypogonadism; hypothalamic-pituitary axis might be especially sensitive to iron. Bone disease Caused by bone marrow expansion, severe iron loading, hypogonadism; osteoporosis in ~50% of patients, even those well treated. Extramedullary hematopoietic masses are a feature of thalassemia intermedia. Infections Transfusion associated; linked to iron overload (Yersinia); malaria. Hematopoietic Stem Cell Transplantation  There is consensus that patients with available donors should be offered transplantation because of the difficulty of lifelong transfusion and chelation and its imperfect efficacy. Quality of life in successfully transplanted patients TABLE 103-6  ` Thalassemias `-GLOBIN GENE ARRANGEMENT HEMOGLOBIN LEVEL, g/L (g/dL)/MCV (fL) CLINICAL FEATURES CLASSIFICATION 120–150 (12–15)/65–80 The chromosome with one deleted α gene (—α/) is called α+ thalassemia (α thalassemia-2); the chromosome with both deleted α genes is α0 thalassemia (α thalassemia-1); non–gene deletion α thalassemias (αT) often have a more severe phenotype. α-Thalassemia trait −α/αα −α/−α − −/αα αTα/αα Hemoglobin H disease − −/−α αTα/− − αTα/αTα 50–120 (5–12)/60–70 Mild to moderate anemia depending on genotype; non–gene deletion forms of α thalassemia can produce severe HbH disease. Hb Bart’s hydrops fetalis −−/−− Fatal in utero or at birth with rare survivors. Hydrops can also result from combinations of gene deletion and non–gene deletion α thalassemia. α Thalassemia/intellectual disability syndromes (ATR-16) (ATR-X) − −/αα or − −/−α in ATR-16 αα/αα in ATR-X αα/αα Mutations in ATRX; striking male predominance. Hematologic findings of HbH disease. α Thalassemia with myelodysplasia (ATMDS) Note: Laboratory values are averages in adults. αα/denotes the chromosome with two intact α-globin genes; –α/chromosome with one α-globin gene deleted; – –/chromosome with both α-globin genes deleted; αT represents non–gene deletion α thalassemia caused by point mutations. The –α/chromosome, referred to as α+ or α thalassemia-2, most often has a deletion of 3.7 kb of DNA (–α3.7) or 4.2 kb of DNA (–α4.2) that leaves a single α-globin gene intact. The chromosome where both α-globin genes are deleted (– –/) is called α0 thalassemia or α thalassemia-1. These chromosomes are caused by different-sized deletions that are usually named after their regions of highest frequency such as -SEA, -MED, -FI, and -THAI. exceeds that in patients treated with transfusion and chelation. Trans­ plantation from matched sibling donors is curative in >80% of all cases. Unfortunately, only a third of patients have matched donors. The best results are in the youngest patients who have been effectively chelated and received fewer transfusions. Graft failure, graft rejection, graft-versus-host disease, and a mortality of 5–20% depending on risk factors are the major drawbacks of this procedure. Results of haploi­ dentical and unrelated donor transplants are improving but lag those of matched sibling donors. Gene Therapy  The same gene therapy approaches approved for sickle cell disease are approved for transfusion-dependent β thalas­ semia (see Sickle Cell Disease). CRISPR/Cas editing to downregulate BCL11A has resulted in increases in total hemoglobin ≥12 g/dL and HbF ≥10 g/dL, leading to transfusion independence in >90% of 52 patients aged between 12 and 35 years with transfusion-dependent β thalassemia. Results of lentiviral-mediated HbAT87Q additive gene therapy were best with non-β0/β0 genotypes, although some individuals with β0/β0 genotypes could be effectively treated as higher viral titers were used in subsequent gene therapy protocols. ` THALASSEMIA In some respects, the obverse of β thalassemia, clinically consequential α thalassemia is less common than severe β thalassemia. α Thalas­ semia is most often found in Asian populations and is usually caused by deletion of α-globin genes rather than point mutations. ■ ■EPIDEMIOLOGY Carriers of the most common α thalassemia chromosomes (Table 103-6) are found in 5–80% of people from tropical and subtropical regions of Africa, the Middle East, Asia, and Melanesia. About 30% of African Americans carry the common –α3.7 chromosome that contains a single functional α-globin gene. HbH disease, the chief clinically important α thalassemia, is most prevalent in southern China and Southeast Asia. Estimates are that in Thailand ~3500 patients with severe α thalas­ semia are born yearly. Pregnancies affected by hemoglobin (Hb) Bart’s hydrops fetalis occur mainly in southern China and southeastern Asia. ■ ■CLASSIFICATION Each normal chromosome 16 contains two α-globin genes; normal diploid individuals have four α-globin genes. A classification of inher­ ited α thalassemia, as summarized in Table 103-6, is based on the number of functional α-globin genes. If one or two α-globin genes are missing or poorly expressed, these people have α thalassemia ATR-16: Large deletions and rearrangements in chr16p. ATR-X: No α-globin gene deletion or mutation, ATRX mutations, X-linked. trait. Their hematologic abnormalities are almost always trivial. HbH disease is usually caused by deletion or malfunction of three α-globin genes. Hb Bart’s hydrops fetalis fetuses have no normally functioning α-globin genes. Hundreds of different-sized deletions and rarer point mutations affect the production of α-globin and the magnitude of imbalanced globin synthesis. Because of this mutational complexity, many different variations of the common α thalassemia syndromes are found. ■ ■PATHOPHYSIOLOGY Reduced accumulation of α-globin leaves non-α-globins unpaired and unable to participate in the formation of functional hemoglobin tetramers. In the fetus, absent or reduced synthesis of α-globin allows unpaired γ-globin chains, part of the HbF tetramer, to form γ4 or Hb Bart’s; in adults, when γ-globin synthesis is mostly silenced, unpaired β-globin chains, lacking a suitable partner to form HbA, tetramerize as β4 or HbH. Both Hb Bart’s and HbH have very high O2 affinity and do not unload O2 in tissues; HbH is also unstable. Severe anemia in Hb Bart’s hydrops fetalis is a result of absent normal hemoglobin and inef­ fective erythropoiesis; in HbH disease, unstable HbH leads to oxidative membrane damage with extravascular hemolysis in the spleen and ineffective erythropoiesis. ■ ■DIAGNOSIS Microcytosis/hypochromia with nearly normal hemoglobin concen­ trations, in the absence of iron deficiency and the increased level of HbA2 that is diagnostic of β thalassemia, is sufficient for a presumptive diagnosis of α thalassemia trait. When genetic counseling is needed and antenatal diagnosis contemplated, the molecular basis of the pre­ sumed α thalassemia is required. HbH disease, which is usually due to compound heterozygosity for one chromosome with both α-globin genes deleted and one chromosome with only a single α-globin gene, is defined by the hematologic findings shown in Table 103-6 along with varying levels of reticulocytosis. At birth, when hemoglobin is separated by HPLC, 20–30% Hb Bart’s is present; in adults, traces to 40% HbH are present along with residual Hb Bart’s in some cases. HbH inclusions can be induced in some red cells after incubation and stain­ ing with brilliant cresyl blue. Hemoglobin composition in Hb Bart’s hydrops fetalis is predominantly Hb Bart’s with some Hb Portland if the deletion removing α-globin genes preserves the ζ-globin gene. ■ ■COMPLICATIONS HbH disease is very heterogeneous because of the different combina­ tions of genotypes that can cause this phenotype. Generally, when non–gene deletion mutants, such as Hb Constant Spring, contribute TABLE 103-7  HbC, HbE, and Rare Hemoglobinopathies CLASSIFICATION CLINICAL ABNORMALITIES HbC trait 2% of African Americans; target cells; no disease Normal HbC: 30–40 HbA2: 2–3 HbC disease Target cells; HbC crystals; mild reticulocytosis; splenomegaly HbE trait 50% incidence in some Asian populations; a few target cells; clinically normal HbE disease No hemolysis; 20–80% target cells; no splenomegaly High O2 affinity hemoglobins Isolated erythrocytosis; often familial; no splenomegaly; no JAK2V617F mutation Low O2 affinity hemoglobins Asymptomatic mild anemia; cyanosis 100–140 (10–14) ~50% variant Unstable hemoglobins Pigmenturia; hemolysis; reticulocytosis; splenomegaly M hemoglobins Some have mild hemolysis; few symptoms 100–140 (10–14)/80–90 20–50% variant depending on gene affected Note: Laboratory values are averages in adults. As noted for HbAS, the amount of HbC and HbE in heterozygotes depends on the number of α-globin genes. to the genotype, the disease is more severe, and intermittent or regular transfusions are necessary. In the most common − −/−α genotype, mean hemoglobin in adults is ~11 g/dL. Hepatosplenomegaly, jaun­ dice, thalassemic bone changes in the face, and growth impairment are seen in 20–50% of cases, depending on the underlying genotype. Iron loading occurs but is not the severe problem it is in β thalassemia. Pregnancy in these patients should be considered high risk and man­ aged accordingly. Mothers of infants with Hb Bart’s hydrops fetalis have a history of stillbirth and develop preeclampsia, polyhydramnios, and antepartum hemorrhage and have difficult labor and delivery. Intra­ uterine transfusion of the fetus is possible. ■ ■MANAGEMENT, SCREENING, COUNSELING, AND ANTENATAL DIAGNOSIS When planning families, couples from regions where α thalassemia is common who have red cell indices that suggest the possibility of carrying an α thalassemia gene should have genetic counseling based on DNA analysis of their globin genes. Iron should be avoided in noniron-deficient individuals with α thalassemia trait and microcytosis. Transfusions are not usually needed in HbH disease. Nevertheless, depending on the genotype of disease, transfusions might be necessary especially when anemia becomes more severe, for example, with acute anemic episodes or pregnancy. Iron stores should be checked periodi­ cally by measuring serum ferritin or MRI; chelation does not appear to be needed. CHAPTER 103 Hb Bart’s hydrops fetalis is best prevented by screening couples at risk and antenatal diagnosis. Intrauterine therapy and perinatal intensive care have permitted survival of some infants with Hb Bart’s hydrops fetalis. As growth retardation affects ~40% and neurodevel­ opmental delay is present in 20% of survivors, prevention is the best approach. Disorders of Hemoglobin OTHER HEMOGLOBINOPATHIES OF CLINICAL IMPORTANCE (TABLE 103-7) More than 1500 mutations affecting hemoglobin structure have been described (www.globin.bx.psu.edu). Most are clinically silent. HbC and HbE are common. HbC is found in people of African descent and HbE in South China and Southeast Asia. Heterozygotes for HbC and HbE are unaffected clinically. Even individuals homozygous for these muta­ tions, where the variant hemoglobin comprises >90% of the hemoly­ sate, are clinically well with very mild anemia and microcytosis. The major importance of these variants is the interaction of HbC with HbS and HbE with β thalassemia, as outlined in Tables 103-2 and 103-4. A definitive diagnosis for all rare variants depends on DNA analysis. HEMOGLOBIN LEVEL, g/L (g/dL)/MCV, fL HEMOGLOBIN FRACTIONS (%) 100–130 (10–13)/60–70 HbC: >95 HbF: 2–4 HbA2: 2–3 120–140 (12–14)/80–90 HbE: 27–31 HbF: 1 HbA2: 3 100–120 (10–12)/65–75 HbE: 85–95 HbF: 3–7 HbA2: 3 150–200 (15–20) Variants in α- and β-globin genes; patients are heterozygotes; ~25–50% variant 90–140 (9–14)/70–90 20–35% variant; rare hyperunstable variants can be undetectable and have the phenotype of thalassemia # 34 - 104 Megaloblastic Anemias ### 104 Megaloblastic Anemias Unexpected low O2 saturation by pulse oximetry (SpO2) with nor­ mal O2 saturation of arterial blood is occasionally seen in rare hemo­ globin variants with clinical phenotypes. Asymptomatic patients with unexpectedly low SpO2 should not be subjected to unneeded cardio­ pulmonary investigations in search of the cause of their “hypoxemia” until the existence of a hemoglobin variant is excluded. ■ ■M HEMOGLOBINS M (met) hemoglobins are characterized by oxidation of the heme-iron from its ferrous (Fe++) to ferric (Fe+++) form. The major clinical feature of these disorders is asymptomatic cyanosis. Thirteen M hemoglobin variants have been described. In nine, the mutation involves histidine residues that interact with heme. Asymptomatic slate gray/brownish pseudocyanosis is the main clinical finding. Spectrophotometric recording of the visible spectrum of the hemolysate is diagnostic. To distinguish M hemoglobins from methemoglobinemia due to drugs or cytochrome b5 reductase (CYB5R3) deficiency, potassium cyanide (KCN) can be added to the hemolysate; methemoglobin-containing blood will turn red, but KCN has no effect on M hemoglobin. Treat­ ment is not needed. ■ ■UNSTABLE HEMOGLOBINS Sometimes referred to as congenital Heinz body hemolytic anemias, some mutations result in a hemoglobin tetramer that is unstable and precipitates intracellularly. One-hundred-fifty-six such variants have been described and are often a result of a new mutation that affects the tertiary or quaternary structure of the molecule. The most com­ mon class of mutations introduce a proline residue in the α helix or a polar amino acid into the interion of the molecule. Heinz bodies are intraerythrocytic precipitates that are detectable as dark globular aggregates after staining with a dye such as brilliant cresyl blue. Three unstable hemoglobins are the most common. Hemoglobin Köln (β99 val-met) has been found in multiple families, Hb Hasharon (α47 asphis) is found in Ashkenazi Jews, and Hb Zurich (β63 his-arg) is suscepti­ ble to oxidant drug-induced hemolysis. Unstable variants present with nonspherocytic hemolytic anemia, but presentation is highly variable. The associated disease is usually mild and does not require transfusion. Heating blood to 50°C or incubation with isopropanol precipitates unstable hemoglobins but must be done with careful controls. Some variants can be detected by HPLC. PART 4 Oncology and Hematology ■ ■HEMOGLOBINS WITH HIGH OXYGEN AFFINITY AND LOW OXYGEN AFFINITY Rare mutations in areas involved in the R-T transition, at critical inter­ faces between globin chains of the tetramer that reduce the affinity for 2,3-bisphosphoglycerate, or present in the heme pocket account for most of these variants. High O2 affinity hemoglobins (103) outnumber low O2 affinity variants (48). Isolated erythrocytosis in the absence of splenomegaly suggests the presence of a high O2 affinity hemoglobin. High O2 affinity hemoglobin variants shift the hemoglobin-O2 disso­ ciation curve leftward, causing a low P50 and thereby stimulating eryth­ ropoiesis. Many of these variants are due to new mutations. The clinical course is benign, and phlebotomy because of erythrocytosis is usually not required. Early diagnosis is important to forestall unnecessary diagnostic procedures and therapeutics such as cardiac catheteriza­ tion to exclude congenital heart disease or treatment for polycythe­ mia vera. Low O2 affinity variants often present with cyanosis. Their hemoglobin-O2 dissociation curve is right-shifted with high P50. HPLC might reveal the presence of a hemoglobin variant. Treatment is often not necessary. ■ ■ACQUIRED DISORDERS OF HEMOGLOBIN CO binds hemoglobin with high affinity forming carboxyhemoglobin. Carboxyhemoglobin levels can be accurately measured by co-oximetry of arterial blood. Standard pulse oximeters cannot accurately make this measurement. Some newly developed pulse oximeters can measure both carboxyhemoglobin and methemoglobin. Bound CO inhibits the transport of O2; the hemoglobin-O2 binding curve is left-shifted. Acute and chronic CO intoxication, caused by occupational exposure and other sources of incomplete combustion of hydrocarbons, presents with headache, altered mental status, and other constitutional symp­ toms. High-flow O2 via facemask is the preferred treatment; criteria have been developed to guide the use of hyperbaric O2. Acquired methemoglobinemia and methemoglobinemia due to deficiency of CYB5R3 are more common than the M hemoglobins. CYB5R3 is required for the reduction of methemoglobin by NADH. Affected individuals with “toxic” methemoglobinemia can be cyanotic and symptomatic. As in carboxyhemoglobinemia, O2 transport is reduced and reflected by the left shift in the hemoglobin-O2 binding curve. CYB5R3 deficiency usually affects only erythrocytes (type I), causing a mild disorder; when all cells are affected (type II), a severe disease results. Intravenous methylene blue is the preferred treatment in symptomatic patients with acquired methemoglobinemia and 40–60% methemoglobin. The usual dose is 1–2 mg/kg. Alternative treatment with ascorbic acid is preferable in people who are glucose-6-phosphate dehydrogenase deficient. Methylene blue interferes with co-oximetry, reducing the value of co-oximetry for monitoring treatment. Many drugs and chemicals can induce methemoglobin in the absence of CYB5R3 deficiency. Dapsone and topical anesthetics such as benzocaine are the most common offending agents. ■ ■FURTHER READING Frangoul H et al: Exagamglogene autotemcel for severe sickle cell disease. N Engl J Med 290:1649, 2024. Hardouon G et al: Sickle cell disease: From genetics to curative approaches. Ann Rev Genomics Hum Genet 24:255, 2023. Leonard A et al: Gene therapy for hemoglobinopathies: Beta-thalassemia, sickle cell disease. Hematol Oncol Clin North Am 36:769, 2022. Locatelli F et al: Defining curative endpoints for sickle cell disease in the era of gene therapy and gene editing. Am J Hematol 99:430, 2024. Piel FB et al: Defining global strategies to improve outcomes in sickle cell disease: A Lancet Haematology Commission. Lancet Haematol. 10:e633, 2023. Pinto VM et al: Management of the aging beta-thalassemia transfusiondependent population: The Italian experience. Blood Rev 38:100594, 2019. Pinto VM et al: Management of the sickle cell trait: An opinion by expert panel members. J Clin Med 12:3441, 2023. Ribeil J-A et al: An integrated therapeutic approach to sickle cell disease management beyond infancy. Am J Hematol 98:1087, 2023. Sheth S et al: Management of luspatercept therapy in patients with transfusion-dependent β-thalassaemia. Br J Haematol 201:824, 2023. Taher AT et al: Beta-thalassemia. N Engl J Med 384:727, 2021. A. Victor Hoffbrand Megaloblastic Anemias The megaloblastic anemias are a group of disorders characterized by the presence of distinctive morphologic appearances of the developing red cells in the bone marrow. The marrow is usually hypercellular, and the anemia is based on ineffective erythropoiesis. The cause is usually a deficiency of either cobalamin (vitamin B12) or folate, but megaloblastic anemia may occur because of genetic or acquired abnormalities that affect the metabolism of these vitamins or because of defects in DNA synthesis not related to cobalamin or folate (Table 104-1). COBALAMIN Cobalamin (vitamin B12) exists in a number of different chemical forms. All have a cobalt atom at the center of a corrin ring. In nature, the vitamin is mainly in the 2-deoxyadenosyl (ado) form, which is located in mitochondria. It is the cofactor for the enzyme L-methylmalonyl TABLE 104-1  Causes of Megaloblastic Anemia Cobalamin deficiency or abnormalities of cobalamin metabolism (see Tables 104-3, 104-4) Folate deficiency or abnormalities of folate metabolism (see Table 104-5) Therapy with antifolate drugs (e.g., methotrexate) Independent of either cobalamin or folate deficiency and refractory to cobalamin and folate therapy:   Some cases of acute myeloid leukemia, myelodysplasia   Therapy with drugs interfering with synthesis of DNA (e.g., cytosine arabinoside, hydroxyurea, 6-mercaptopurine, azidothymidine [AZT])   Orotic aciduria (responds to uridine)   Thiamine-responsive coenzyme A (CoA) mutase. The other major natural cobalamin is methylcobalamin, the form in human plasma and in cell cytoplasm. It is the cofactor for methionine synthase. Minor amounts of hydroxo­ cobalamin are also present to which methyl- and ado-cobalamin are converted rapidly by exposure to light. ■ ■DIETARY SOURCES AND REQUIREMENTS Cobalamin is synthesized solely by microorganisms. Ruminants obtain cobalamin from the foregut, but the only source for humans is food of animal origin, for example, meat, fish, and dairy products. Vegetables, fruits, and other foods of nonanimal origin are free from cobalamin unless they are contaminated by bacteria. A normal Western diet con­ tains 5–30 μg of cobalamin daily. Adult daily losses (mainly in the urine and feces) are 1–3 μg (∼0.1% of body stores), and because the body does not have the ability to degrade cobalamin, daily requirements are also about 1–3 μg. Body stores are of the order of 2–3 mg, sufficient for 3–4 years if supplies are completely cut off. ■ ■ABSORPTION Two mechanisms exist for cobalamin absorption. One is passive, occur­ ring equally through buccal, duodenal, and ileal mucosa; it is rapid but extremely inefficient, with <1% of an oral dose being absorbed by this process. The normal physiologic mechanism is active; it occurs through the ileum and is efficient for small (a few micrograms) oral doses of cobalamin, and it is mediated by gastric intrinsic factor (IF). Dietary cobalamin is released from protein complexes by enzymes in the stomach, duodenum, and jejunum; it combines rapidly with a salivary glycoprotein that belongs to the family of cobalamin-binding proteins known as haptocorrins (HCs). In the intestine, the HC is digested by pancreatic trypsin and the cobalamin is transferred to IF. IF (gene at chromosome 11q13) is produced in the gastric parietal cells of the fundus and body of the stomach, and its secretion parallels that of hydrochloric acid. Normally, a vast excess of IF is available. The IF-cobalamin complex passes to the ileum, where IF attaches to a specific receptor (cubilin) on the microvillus membrane of the enterocytes. Cubilin also is present in yolk sac and renal proximal tubular epithelium. Cubilin appears to traffic by means of amnionless (AMN), an endocytic receptor protein that directs sublocalization and endocytosis of cubilin with its ligand IF-cobalamin complex. The cobalamin-IF complex enters the ileal cell, where IF is destroyed. After a delay of about 6 h, the cobalamin appears in portal blood attached to transcobalamin (TC) II. Between 0.5 and 5 μg of cobalamin enter the bile each day. This binds to IF, and a major portion of biliary cobalamin normally is reab­ sorbed together with cobalamin derived from sloughed intestinal cells. Because of the appreciable amount of cobalamin undergoing entero­ hepatic circulation, cobalamin deficiency develops more rapidly in individuals who malabsorb cobalamin than it does in vegans, in whom reabsorption of biliary cobalamin is intact. ■ ■TRANSPORT Two main cobalamin transport proteins exist in human plasma; they both bind cobalamin—one molecule for one molecule. One an HC, also known as transcobalamin (TC) I, is closely related to other cobalamin-binding HCs in milk, gastric juice, bile, saliva, and other fluids. The gene TCNL is at chromosome 11q11-q12.3. These HCs differ from each other only in the carbohydrate moiety of the molecule. TC I is derived primarily from the specific granules in neutrophils. Normally, it is about two-thirds saturated with cobalamin, which it binds tightly. TC I does not enhance cobalamin entry into tissues. Glycoprotein receptors on liver cells are involved in the removal of TC I from plasma, and TC I may play a role in the transport of cobalamin analogues (which it binds more effectively than does IF) to the liver for excretion in bile. The other major cobalamin transport protein in plasma is transco­ balamin, also known as TC II. The gene is on chromosome 22q11-q13.1. As for IF and HCs, there are nine exons. The three proteins are likely to have a common ancestral origin. TC II is synthesized by liver and by other tissues, including macrophages, ileum, and vascular endothelium. It normally carries only 20–60 ng of cobalamin per liter of plasma and readily gives up cobalamin to marrow, placenta, and other tissues, which it enters by receptor-mediated endocytosis involving the TC II receptor and megalin (encoded by the LRP-2 gene). The TC II cobalamin is inter­ nalized by endocytosis via clathrin-coated pits; the complex is degraded, but the receptor probably is recycled to the cell membrane as is the case for transferrin. Export of “free” cobalamin is via the ATP-binding cas­ sette drug transporter alias multidrug resistance protein 1. CHAPTER 104 FOLATE ■ ■DIETARY FOLATE Folic (pteroylglutamic) acid is a yellow, crystalline, water-soluble substance. It is the parent compound of a large family of natural folate compounds, which differ from it in three respects: (1) they are partly or completely reduced to dihydrofolate (DHF) or tetrahydrofolate (THF) derivatives, (2) they usually contain a single carbon unit (Table 104-2), and (3) 70–90% of natural folates are folate-polyglutamates. These usually have a chain of four to six glutamate moieties rather than one, as in the monoglutamate folic acid. The whole family is known as folate or vitamin B9. Megaloblastic Anemias Most foods contain some folate. The highest concentrations are found in liver, yeast, spinach, other greens, and nuts (>100 μg/100 g). The total folate content of an average Western diet is 400−500 μg daily, but the amount varies widely according to the type of food eaten and the method of cooking. Folate is easily destroyed by heating, particu­ larly in large volumes of water. Total-body folate in the adult is ∼10 mg, with the liver containing the largest store. Daily adult requirements are 100–200 μg, and so stores are sufficient for only 3–4 months in normal adults, and severe folate deficiency may develop rapidly. ■ ■ABSORPTION Folates are absorbed rapidly from the upper small intestine. The absorption of folate polyglutamates is less efficient than that of mono­ glutamates; on average, ∼50% of food folate is absorbed. Polyglutamate forms are hydrolyzed to the monoglutamate derivatives either in the lumen of the intestine or within the mucosa. All dietary folates are converted to 5-methyl-THF (5-MTHF) within the small intestinal mucosa before entering portal plasma. Monoglutamates are actively transported across the enterocyte by a proton-coupled folate trans­ porter (PCFT, SCL46A1). This is situated at the apical brush border and is most active at pH 5.5, which is about the pH of the duodenal and jejunal surface. Genetic mutations of this protein underlie heredi­ tary malabsorption of folate (see below). Pteroylglutamic acid at doses >400 μg is absorbed largely unchanged and converted to natural folates in the liver. Lower doses are converted to 5-MTHF during absorption through the intestine. About 60–90 μg of folate enter the bile each day and are excreted into the small intestine. Loss of this folate, together with the folate of sloughed intestinal cells, accelerates the speed with which folate defi­ ciency develops in malabsorption conditions. ■ ■TRANSPORT Folate is transported in plasma; about one-third is loosely bound to albumin, and two-thirds are unbound. In all body fluids (plasma, cerebrospinal fluid, milk, bile), folate is largely, if not entirely, 5-MTHF TABLE 104-2  Biochemical Reactions of Folate Coenzymes COENZYME FORM OF FOLATE INVOLVED REACTION Formate activation THF −CHO Generation of 10-formyl-THF Purine synthesis         Formation of glycinamide 5,10-Methylene-THF −CHO Formation of purines needed for DNA, RNA synthesis, but reactions probably not rate-limiting ribonucleotide   Formylation of aminoimidazole 10-Formyl (CHO)THF     carboxamide ribonucleotide (AICAR) Pyrimidine synthesis         Methylation of deoxyuridine 5,10-Methylene-THF −CH3 Rate limiting in DNA synthesis Oxidizes THF to DHF Some breakdown of folate at the C-9–N-10 bond monophosphate (dUMP) to thymidine monophosphate (dTMP) Amino acid interconversion         Serine-glycine interconversion THF =CH2 Entry of single carbon units into active pool   Homocysteine to methionine 5-Methyl(M)THF −CH3 Demethylation of 5-MTHF to THF; also requires cobalamin, flavine adenine dinucleotide, ATP, and adenosylmethionine   Forminoglutamic acid to glutamic THF −HN−CH=   acid in histidine catabolism Abbreviations: DHF, dihydrofolate; THF, tetrahydrofolate. PART 4 Oncology and Hematology (the monoglutamate form). Three types of folate-binding protein are involved. A reduced folate transporter (RFC, SLC19A1) is the major route of delivery of plasma folate (5-MTHF) to cells. Two folate recep­ tors, FR2 and FR3 embedded in the cell membrane by a glycosyl phosphatidylinositol anchor, transport folate into the cell via receptormediated endocytosis. The third protein, proton-coupled folate trans­ porter (PCFT), transports folate at low pH from the vesicle to the cell cytoplasm. The reduced folate transporter also mediates uptake of methotrexate by cells. ■ ■BIOCHEMICAL FUNCTIONS Folates (as the intracellular polyglutamate derivatives) act as coenzymes in the transfer of single-carbon units (Fig. 104-1 and Table 104-2). Two of these reactions are involved in purine synthesis and one in pyrimi­ dine synthesis necessary for DNA and RNA replication. Folate is also a coenzyme for methionine synthesis, in which methylcobalamin is also involved and in which THF is regenerated. THF is the acceptor of single carbon units newly entering the active pool via conversion of serine to glycine. Methionine, the other product of the methionine synthase reaction, is the precursor for S-adenosylmethionine (SAM), the universal methyl donor involved in >100 methyltransferase reac­ tions (Fig. 104-1). During thymidylate synthesis, 5,10-methylene-THF is oxidized to DHF. The enzyme DHF reductase converts this to THF. The drugs methotrexate, pyrimethamine, and (mainly in bacteria) trimethoprim inhibit DHF reductase and so prevent formation of active THF coen­ zymes from DHF. A small fraction of the folate coenzyme is not recy­ cled during thymidylate synthesis but is degraded at the C9-N10 bond. BIOCHEMICAL BASIS OF MEGALOBLASTIC ANEMIA The common feature of all megaloblastic anemias is a defect in DNA synthesis that affects rapidly dividing cells in the bone marrow. Con­ ditions that give rise to megaloblastic changes have in common a disparity in the availability of the four immediate precursors of DNA or a block in their condensation to form DNA. The four precursors are the deoxyribonucleoside triphosphates (dNTPs)—dA(adenine) TP and dG(guanine)TP (purines), dT(thymine)TP, and dC(cytosine) TP (pyrimidines). In deficiencies of either folate or cobalamin, con­ version of deoxyuridine monophosphate (dUMP) to deoxythymidine monophosphate (dTMP), the precursor of deoxythymidine triphos­ phate (dTTP) (Fig. 104-1) fails. This occurs because folate is needed as the coenzyme 5,10-methylene-THF polyglutamate for conversion of dUMP to dTMP. The availability of 5,10-methylene-THF is reduced in either cobalamin or folate deficiency. Because of the shortage of one SINGLE CARBON UNIT TRANSFERRED IMPORTANCE or more precursor, DNA replication from multiple origins along the chromosome is slower than normal during mitosis, and the incomplete replicons fail to join up with resulting single-stranded DNA breaks. An alternative and less likely theory for megaloblastic anemia in cobalamin or folate deficiency is misincorporation of uracil into DNA because of the accumulation of deoxyuridine triphosphate (dUTP) at the DNA replication fork as a consequence of the block in conversion of dUMP to dTMP. ■ ■COBALAMIN-FOLATE RELATIONS Folate is required for many reactions in mammalian tissues (Table 104-2). Only two reactions in the body are known to require cobalamin. Methylmalonyl-CoA isomerization requires adocobalamin, and the methylation of homocysteine to methionine requires both methylco­ balamin and 5-MTHF (Fig. 104-1). This reaction is the first step in the pathway by which 5-MTHF, which enters bone marrow and other cells from plasma, is converted into all the intracellular folate coen­ zymes. The coenzymes are all polyglutamated (the larger size aiding retention in the cell), but the enzyme folate polyglutamate synthase can use only THF, not 5-MTHF, as substrate. In cobalamin deficiency, 5-MTHF accumulates in plasma, and intracellular folate concentra­ tions fall due to failure of formation of THF, the substrate on which folate polyglutamates are built. This has been termed THF starvation, or the methylfolate trap. This trap also occurs at the polyglutamate level with accumulation of the methyl form at the expense of the other one-carbon forms. This theory explains the abnormalities of folate metabolism that occur in cobalamin deficiency (high serum folate, low cell folate, positive purine precursor aminoimidazole carboxamide ribonucleotide [AICAR] excretion) (Table 104-2) and also why the anemia of cobala­ min deficiency responds to folic acid in large doses, which overcome the methylfolate trap (Fig 104-1). CLINICAL FEATURES Many symptomless patients are detected through the finding of a raised mean corpuscular volume (MCV) on a routine blood count. The main clinical features in more severe cases are those of anemia. Anorexia is usually marked, and weight loss, diarrhea, or constipation may be present. Glossitis, angular cheilosis, a mild fever in more severely anemic patients, jaundice (unconjugated), and reversible melanin skin hyperpigmentation also may occur with a deficiency of either folate or cobalamin. Thrombocytopenia sometimes leads to bruising, and this may be aggravated by vitamin C deficiency or alcohol in malnourished patients. The anemia and low leukocyte count may predispose to infec­ tions, particularly of the respiratory and urinary tracts. Cobalamin Methylated product (e.g., methylated lipids, myelin basic protein, DOPA, DNA) GSH Pyruvate S-Adenosylhomocysteine (SAH) Cysteine Cystathionine Cystathionine synthase vitamin B6 Homocysteine Methionine Cell Tetrahydrofolate 5-Methyl tetrahydrofolate 5,10-Methylenetetrahydrofolate reductase 5, 10-Methylene tetrahydrofolate 5-Methyl tetrahydrofolate (monoglutamate) Deoxyuridine monophosphate Folic acid Folic acid Plasma FIGURE 104-1  The role of folates in DNA synthesis and in formation of S-adenosylmethionine (SAM), which is involved in numerous methylation reactions. DHF, dihydrofolate; GSH, glutathione. (Reproduced with permission from AV Hoffbrand et al [eds]: Postgraduate Haematology, 5th ed. Oxford, UK, Blackwell Publishing, 2005.) deficiency has also been associated in a few studies with impaired bactericidal function of phagocytes and with osteoporosis. Neurologic Manifestations  Cobalamin is needed for the myelin­ ation of the central nervous system. Its deficiency may cause a bilateral peripheral neuropathy or degeneration (demyelination) of the cervical and thoracic posterior and lateral (pyramidal) tracts of the spinal cord and, less frequently, of the cranial nerves and of the white matter of the brain. Optic atrophy and cerebral symptoms including dementia, depression, psychotic symptoms, and cognitive impairment may be prominent. Anosmia and loss of taste may occur. Magnetic resonance imaging (MRI) may show the “spongy” degeneration of the cord. The patient, more frequently male, typically presents with pares­ thesias, muscle weakness, or difficulty in walking but sometimes may present with dementia, psychotic disturbances, or visual impairment. Loss of proprioception and vibration sensation is usually present with positive Romberg and Lhermitte signs. Gait may be ataxic with spas­ ticity (hyperreflexia). Autonomic nervous dysfunction can result in postural hypotension, impotence, and incontinence. Long-term nutritional cobalamin deficiency in infancy leads to poor brain development and impaired intellectual development. In infancy, feeding difficulties, lethargy, and coma may be noted. Convulsions Substrate Methyltransferases S-Adenosylmethionine (SAM) THE METHYLATION CYCLE ATP Polyglutamate synthase + glutamates Methionine synthase methylcobalamin DHF reductase Serine Glycine CHAPTER 104 Purines Formate Dihydrofolate 10-Formyl tetrahydrofolate DNA CYCLE (CELL REPLICATION) Megaloblastic Anemias Deoxythymidine monophosphate and myoclonus have been described. An important clinical problem is the nonanemic patient with neurologic or psychiatric abnormalities and a low or borderline serum cobalamin level. In such patients, it is necessary to try to establish whether significant cobalamin deficiency is present, for example, by careful examination of the blood film for macrocytosis or hypersegmented neutrophils (see below), tests for pernicious anemia (PA) by serum gastrin level and antibodies to IF or parietal cells, and serum methylmalonic acid (MMA) measurement. A trial of cobalamin therapy for at least 3 months will usually also be needed to determine whether the symptoms improve. The biochemical basis for cobalamin neuropathy remains obscure. Its occurrence in the absence of methylmalonic aciduria in TC II deficiency suggests that the neuropathy is related to the defect in homocysteine-methionine conversion. Accumulation of S-adenosyl­ homocysteine in the brain, resulting in inhibition of transmethylation reactions, has been suggested. Folate deficiency has been suggested to cause organic neurologic disease, but this is uncertain, although methotrexate injected into the cerebrospinal fluid may cause brain or spinal cord damage. Psychiatric disturbance, as discussed above, is common in both folate and cobalamin deficiencies. This, like the neuropathy, has been attributed to a failure of the synthesis of SAM, which is needed in methylation of biogenic amines (e.g., dopamine) as well as that of pro­ teins, phospholipids, and neurotransmitters in the brain (Fig. 104-1). ■ ■GENERAL TISSUE EFFECTS OF COBALAMIN AND FOLATE DEFICIENCIES Epithelial Surfaces  After the marrow, the next most frequently affected tissues are the epithelial cell surfaces of the mouth (with glos­ sitis), stomach, small intestine, and respiratory, urinary, and female genital tracts. The cells show macrocytosis with increased numbers of multinucleate and dying cells. The deficiencies may cause cervical smear abnormalities. Complications of Pregnancy  The gonads are also affected, and infertility is common in both men and women with severe deficiency of either vitamin. Maternal folate deficiency has been implicated as a cause of prematurity, and both folate and cobalamin deficiencies have been implicated in recurrent fetal loss and neural tube defects. Neural Tube Defects  Folic acid supplements at the time of con­ ception and in the first 12 weeks of pregnancy can reduce by ∼80% the incidence of neural tube defects (NTDs) (anencephaly, meningomyelo­ cele, encephalocele, and spina bifida) in the fetus. Most of this protec­ tive effect can be achieved by taking folic acid, 0.4 mg daily, before and at the time of conception. PART 4 Oncology and Hematology The incidence of cleft palate and harelip also can be reduced by prophylactic folic acid. No clear simple relationship exists between maternal folate status and these fetal abnormalities, although for NTDs, it has been established that the lower the maternal folate, the greater is the risk to the fetus. NTDs also can be caused by antifolate and antiepileptic drugs. An underlying maternal folate metabolic abnormality has also been postulated. One abnormality has been identified: reduced activity of the enzyme 5,10-methylene-THF reductase (MTHFR) (Fig. 104-1) caused by a common C677T polymorphism in the MTHFR gene. In one study, the prevalence of this polymorphism was found to be higher than in controls in the parents of NTD fetuses and in the fetuses them­ selves: homozygosity for the TT mutation was found in 13% of cases compared with 5% of control subjects. The polymorphism codes for a thermolabile form of MTHFR. The homozygous state results in a lower mean serum and red cell folate level compared with control subjects, as well as significantly higher serum homocysteine levels. Tests for muta­ tions in other enzymes possibly associated with NTDs, for example, methionine synthase and serine–glycine hydroxymethylase, have been negative. Serum cobalamin levels are also lower in the sera of mothers of NTD infants than in controls. In addition, maternal TC II receptor polymorphisms are associated with increased risk of NTD births. How­ ever, no studies have been undertaken that show that dietary fortifica­ tion with cobalamin reduces the incidence of NTDs. Cardiovascular Disease  Children with severe homocystinuria (blood levels ≥100 μmol/L) due to deficiency of one of three enzymes (methionine synthase, MTHFR, or cystathionine synthase; Fig. 104-1) have vascular disease, for example, ischemic heart disease, cerebrovas­ cular disease, or pulmonary embolus, as teenagers or in young adult­ hood. Lesser degrees of raised serum homocysteine and low levels of serum folate and homozygous inherited mutations of MTHFR have been found to be associated with cerebrovascular, peripheral vascular, and coronary heart disease and with deep vein thrombosis. Prospective randomized trials of lowering homocysteine levels with supplements of folic acid, vitamin B12, and vitamin B6 against placebo over a 5-year period in patients with vascular disease or diabetes have not, however, shown a reduction of first event fatal or nonfatal myocardial infarction, nor have these supplements reduced the risk of recurrent cardiovascu­ lar disease after an acute myocardial infarct. Meta-analysis showed an 18% reduction in strokes. The benefit for stroke prevention has been confirmed by a large (>20,000 subjects) randomized prospective study in hypertensive subjects in China. This showed a significant reduction in the first incidence of stroke in subjects receiving enalapril and folic acid compared to enalapril alone. The effect was especially marked in the subjects commencing the prospective trial with the lowest serum folate levels. Venous thrombosis has been reported to be more frequent in folate-deficient or cobalamin-deficient subjects than in controls and to occur at unusual sites such as cerebral venous sinuses. This tendency was ascribed to raised plasma homocysteine levels in folate or cobala­ min deficiency, but no evidence exists that folic acid or cobalamin supplements reduce the prevalence of venous thrombosis. Cognitive Decline  Association between low serum folate or cobalamin levels and higher homocysteine levels with the development of decreased cognitive function and of dementia in Alzheimer’s disease has been reported. A meta-analysis of randomized, placebo-controlled trials of homocysteine-lowering B-vitamin supplementation of indi­ viduals with and without cognitive impairment, however, showed that supplementation with vitamin B12, vitamin B6, and folic acid alone or in combination did not improve cognitive function or slow cognitive decline. It is unknown whether prolonged treatment with these B vitamins can reduce the risk of dementia in later life. Malignancy  Prophylactic folic acid in pregnancy has been found in some but not all studies to reduce the subsequent incidence of acute lymphoblastic leukemia (ALL) in childhood. A significant negative association has also been found with the MTHFR C677T polymor­ phism and leukemias with mixed lineage leukemia (MLL) transloca­ tions, but a positive association was found with hyperdiploidy in infants with ALL or acute myeloid leukemia or with childhood ALL. A second polymorphism in the MTHFR gene, A1298C, is also strongly associated with hyperdiploid leukemia. Various positive and negative associations are noted between polymorphisms in folate-dependent enzymes and the incidence of adult ALL. The C677T polymorphism is thought to lead to increased thymidine pools and “better quality” of DNA synthesis by shunting one-carbon groups toward thymidine and purine synthesis. This may explain its reported association with a lower risk for colorectal cancer. Most but not all studies suggest that prophy­ lactic folic acid also protects against colon adenomas. Other tumors that have been associated with folate polymorphisms or status include follicular lymphoma, breast cancer, and gastric cancer. A meta-analysis of 50,000 individuals given folic acid (0.5–40 mg daily) or placebo in cardiovascular (n = 10) or colon adenoma pre­ vention (n = 3) trials found that folic acid supplementation did not significantly increase or decrease the overall incidence of cancer or of any site-specific cancer during a weighted average scheduled treatment duration of 5.7 years. Because folic acid may “feed” tumors, it prob­ ably should be avoided in those with established tumors unless severe megaloblastic anemia due to folate deficiency is present. HEMATOLOGIC FINDINGS ■ ■PERIPHERAL BLOOD Oval macrocytes, usually with considerable anisocytosis and poikilo­ cytosis, are the main feature (Fig. 104-2A). The MCV is usually >100 fL unless a cause of microcytosis (e.g., iron deficiency or thalassemia trait) is present. Some of the neutrophils are hypersegmented (more than five nuclear lobes). There may be leukopenia due to a reduction in granulocytes and lymphocytes, but this is usually >1.5 × 109/L; the platelet count may be moderately reduced, rarely to <40 × 109/L. The severity of all these changes parallels the degree of anemia. In a non­ anemic patient, the presence of a few macrocytes and hypersegmented neutrophils in the peripheral blood may be the only indication of the underlying disorder. ■ ■BONE MARROW In a severely anemic patient, the marrow is hypercellular with an accu­ mulation of primitive cells due to selective death by apoptosis of more mature forms. The erythroblast nucleus maintains a primitive, fine chromatin appearance despite maturation and hemoglobinization of the cytoplasm. The cells are larger than normoblasts, and an increased number of cells with eccentric lobulated nuclei or nuclear fragments may be present (Fig. 104-2B). Giant and abnormally shaped meta­ myelocytes and enlarged hyperpolyploid megakaryocytes are charac­ teristic. In severe cases, the accumulation of primitive cells (“blasts”) B A FIGURE 104-2  A. The peripheral blood in severe megaloblastic anemia. B. The bone marrow in severe megaloblastic anemia. (Reprinted from AV Hoffbrand et al [eds]: Postgraduate Haematology, 5th ed. Oxford, UK, Blackwell Publishing, 2005; with permission.) may mimic acute myeloid leukemia, whereas in less anemic patients, the changes in the marrow may be difficult to recognize. The terms intermediate, mild, and early have been used. The term megaloblastoid is best avoided. It has been used to describe cells with both immatureappearing nuclei and defective hemoglobinization refractory to folic acid or cobalamin therapy, especially seen in myelodysplasia. ■ ■CHROMOSOMES Bone marrow cells, transformed lymphocytes, and other proliferating cells in the body show a variety of chromosomal changes, including random breaks, reduced contraction, spreading of the centromere, and exaggeration of secondary chromosomal constrictions and over­ prominent satellites. Similar abnormalities may be produced by antimetabolite drugs (e.g., cytarabine, hydroxyurea, thioguanine, and methotrexate) that interfere with either DNA replication or folate metabolism and that also cause megaloblastic appearances. ■ ■INEFFECTIVE HEMATOPOIESIS Unconjugated bilirubin accumulates in plasma due to the death of nucleated red cells in the marrow (ineffective erythropoiesis). Other evidence for this includes raised urine urobilinogen, reduced hapto­ globins, positive urine hemosiderin, and raised serum lactate dehydro­ genase. A weakly positive direct antiglobulin test due to complement only can lead to a false diagnosis of autoimmune hemolytic anemia. CAUSES OF COBALAMIN DEFICIENCY Cobalamin deficiency is usually due to malabsorption. The only other cause is inadequate dietary intake. ■ ■INADEQUATE DIETARY INTAKE Adults  Dietary cobalamin deficiency arises in vegans who omit meat, fish, eggs, cheese, and other animal products from their diet. The largest group in the world consists of Hindus, and it is likely that many millions of Indians are at risk of deficiency of cobalamin on a nutritional basis. Subnormal serum cobalamin levels are found in up to 50% of randomly selected, young, adult Indian vegans, but the defi­ ciency usually does not progress to megaloblastic anemia since the diet of most vegans is not totally lacking in cobalamin and the enterohe­ patic circulation of cobalamin is intact. Dietary cobalamin deficiency may also arise rarely in nonvegetarian individuals who exist on grossly inadequate diets because of poverty or psychiatric disturbance. CHAPTER 104 Megaloblastic Anemias Infants  Cobalamin deficiency has been described in infants born to severely cobalamin-deficient mothers. These infants develop mega­ loblastic anemia at about 3–6 months of age, presumably because they are born with low stores of cobalamin and because they are fed breast milk with low cobalamin content. The babies have also shown growth retardation, impaired psychomotor development, and other neurologic sequelae. MRI shows delayed myelination and brain atrophy. ■ ■GASTRIC CAUSES OF COBALAMIN MALABSORPTION See Tables 104-3 and 104-4. Formerly, the pathogenesis of cobalamin malabsorption was distin­ guishable based on the results of a Schilling test in which a radioac­ tive form of cobalamin was administered orally and its appearance in the urine was a sign of absorption. Radioactive cobalamin is no longer available, and Schilling tests are no longer performed. Other approaches to the differential diagnosis of cobalamin malabsorption are now employed. Pernicious Anemia  PA, the dominant cause of severe cobalamin deficiency in Western countries, may be defined as a severe lack of IF due to gastric atrophy. It is a common disease in northern Europeans but occurs in all countries and ethnic groups. It is more frequent in people of African than Asian ancestry. The overall incidence is about TABLE 104-3  Causes of Cobalamin Deficiency Sufficiently Severe to Cause Megaloblastic Anemia NUTRITIONAL VEGANS Malabsorption Pernicious anemia Gastric causes Congenital absence of intrinsic factor or functional abnormality   Total or partial gastrectomy Intestinal causes Intestinal stagnant loop syndrome: jejunal diverticulosis, ileocolic fistula, anatomic blind loop, intestinal stricture, etc.   Ileal resection and Crohn’s disease   Selective malabsorption with proteinuria   Tropical sprue   Transcobalamin II deficiency   Fish tapeworm TABLE 104-4  Malabsorption of Cobalamin May Occur in the Following Conditions but Is Not Usually Sufficiently Severe and Prolonged to Cause Megaloblastic Anemia Gastric causes   Simple atrophic gastritis (food cobalamin malabsorption)   Zollinger-Ellison syndrome   Gastric bypass or bariatric surgery   Use of proton pump inhibitors Intestinal causes   Gluten-induced enteropathy   Severe pancreatitis   HIV infection   Radiotherapy   Graft-versus-host disease Deficiencies of cobalamin, folate, protein,? riboflavin,? nicotinic acid Therapy with colchicine, para-aminosalicylate, neomycin, slow-release potassium chloride, anticonvulsant drugs, metformin,a cytotoxic drugs Alcohol aIt is now thought that metformin lowers serum vitamin B12 level by lowering the level of transcobalamin I. PART 4 Oncology and Hematology 120 per 100,000 population in the United Kingdom (UK). The ratio of incidence in men and women among whites is ∼1:1.6, and the median age of onset is 70–80 years, with only 10% of patients being <40 years of age. However, in some ethnic groups, notably blacks and Latin Americans, the age at onset of PA is generally lower. The disease occurs more commonly than by chance in close relatives and in persons with other organ-specific autoimmune diseases, for example, thyroid diseases, vitiligo, hypoparathyroidism, type 1 diabetes, and Addison’s disease. It is also associated with hypogammaglobulinemia, premature graying or blue eyes, and persons of blood group A. An association with human leukocyte antigen (HLA) 3 has been reported in some but not all series and, in those with endocrine disease, with HLA-B8, -B12, and -BW15. Life expectancy is normal in women once regular treatment has begun. Men had in earlier decades a slightly subnormal life expectancy as a result of a higher incidence of carcinoma of the stomach than in con­ trol subjects, but current data on their life expectancy are unavailable. Gastric output of hydrochloric acid, pepsin, and IF is severely reduced. The serum gastrin level is raised, and serum pepsinogen I levels are low. Gastric Biopsy  A single endoscopic examination is recommended if PA is diagnosed. Gastric biopsy usually shows atrophy of all layers of the body and fundus, with loss of glandular elements, an absence of parietal and chief cells and replacement by mucous cells, a mixed inflammatory cell infiltrate, and perhaps intestinal metaplasia. The infiltrate of plasma cells and lymphocytes contains an excess of CD4 cells. These are directed against gastric H/K-ATPase. The antral mucosa is usually well preserved. Helicobacter pylori infection occurs infrequently in PA, but it has been suggested that H. pylori gastritis occurs at an early phase of atrophic gastritis and presents in younger patients as iron-deficiency anemia and in older patients as PA. H. pylori is suggested to stimulate an autoimmune process directed against pari­ etal cells. It has been suggested that H. pylori infection is replaced, in some individuals, by the autoimmune process. Serum Antibodies  Two types of IF immunoglobulin G antibody may be found in the sera of patients with PA. The “blocking,” or type I, antibody prevents the combination of IF and cobalamin, whereas the “binding,” or type II, antibody prevents attachment of IF to ileal mucosa. Type I occurs in the sera of ∼55% of patients, and type II in 35%. IF antibodies cross the placenta and may cause temporary IF deficiency in a newborn infant. Type I antibody has been detected rarely in the sera of patients without PA but with thyrotoxicosis, myxedema, Hashimoto’s disease, or diabetes mellitus and in relatives of PA patients. IF antibodies have also been detected in gastric juice in ∼80% of PA patients. These gastric antibodies may reduce absorption of dietary cobalamin by combining with small amounts of remaining IF. Patients with PA also show cell-mediated immunity to IF. Parietal cell antibody is present in the sera of almost 90% of adult patients with PA but is frequently present in other subjects. Thus, it occurs in as many as 16% of randomly selected female subjects age >60 years. The parietal cell antibody is directed against the α and β subunits of the gastric proton pump (H+, K+-ATPase). ■ ■JUVENILE PERNICIOUS ANEMIA This usually occurs in older children and resembles PA of adults. Gastric atrophy, achlorhydria, and serum IF antibodies are all present, although parietal cell antibodies are usually absent. About one-half of these patients show an associated endocrinopathy such as autoimmune thyroiditis, Addison’s disease, or hypoparathyroidism; in some, muco­ cutaneous candidiasis occurs. ■ ■CONGENITAL INTRINSIC FACTOR DEFICIENCY OR FUNCTIONAL ABNORMALITY An affected child usually presents with megaloblastic anemia in the first to third year of life; a few have presented as late as the second decade. The child usually has no demonstrable IF but has a normal gastric mucosa and normal secretion of acid. The inheritance is auto­ somal recessive. Parietal cell and IF antibodies are absent. Variants have been described in which the child is born with IF that can be detected immunologically but is unstable or functionally inactive, unable to bind cobalamin or to facilitate its uptake by ileal receptors. ■ ■GASTRECTOMY After total gastrectomy, cobalamin deficiency is inevitable, and pro­ phylactic cobalamin therapy should be commenced immediately after the operation. After partial gastrectomy, 10–15% of patients also develop this deficiency. The exact incidence and time of onset are most influenced by the size of the resection and the preexisting size of cobalamin body stores. ■ ■FOOD COBALAMIN MALABSORPTION Failure of release of cobalamin from binding proteins in food is responsible for this condition, which is more common in the elderly. It is associated with low serum cobalamin levels, with or without raised serum levels of MMA and homocysteine. Typically, these patients have normal cobalamin absorption, as measured with crystalline cobala­ min, but show malabsorption when a modified test using food-bound cobalamin is used. It is usually due to mild forms of atrophic gastritis or therapy with proton pump inhibitors. Bariatric surgery is likely to be an increasing cause of this form of cobalamin malabsorption and defi­ ciency. The frequency of progression to severe cobalamin deficiency and the reasons for this progression are not clear. ■ ■INTESTINAL CAUSES OF COBALAMIN MALABSORPTION Intestinal Stagnant Loop Syndrome  Malabsorption of cobala­ min occurs in a variety of intestinal lesions in which there is coloniza­ tion of the upper small intestine by fecal organisms. This may occur in patients with jejunal diverticulosis, entero-anastomosis, or an intestinal stricture or fistula or with an anatomic blind loop due to Crohn’s dis­ ease, tuberculosis, or an operative procedure. Ileal Resection  Removal of ≥1.2 m of terminal ileum causes malabsorption of cobalamin. In some patients after ileal resection, particularly if the ileocecal valve is incompetent, colonic bacteria may contribute further to the onset of cobalamin deficiency. Selective Malabsorption of Cobalamin with Proteinuria (Imerslund’s Syndrome; Imerslund-Gräsbeck Syndrome; Congenital Cobalamin Malabsorption; Autosomal Reces­ sive Megaloblastic Anemia; MGA1)  This autosomal recessive disease is the most common cause of megaloblastic anemia due to cobalamin deficiency in infancy in Western countries. More than 200 cases have been reported with familial clusters in Finland, Norway, the Middle East, and North Africa. The patients secrete normal amounts of IF and gastric acid but are unable to absorb cobalamin. In Finland, impaired synthesis, processing, or ligand binding of cubilin due to inherited mutations is found. In Norway, mutation of the gene for AMN has been reported. Other tests of intestinal absorption are nor­ mal. Over 90% of these patients show nonspecific proteinuria, but renal function is otherwise normal, and renal biopsy has not shown any con­ sistent renal defect. A few have shown aminoaciduria and congenital renal abnormalities, such as duplication of the renal pelvis. Tropical Sprue  Nearly all patients with acute and subacute tropi­ cal sprue show malabsorption of cobalamin. This may persist as the principal abnormality in the chronic form of the disease, when the patient may present with megaloblastic anemia or neuropathy due to cobalamin deficiency. Absorption of cobalamin usually improves after antibiotic and, in the early stages, folic acid therapy. Fish Tapeworm Infestation  The fish tapeworm (Diphylloboth­ rium latum) lives in the small intestine of humans and accumulates cobalamin from food, rendering the cobalamin unavailable for absorp­ tion. Individuals acquire the worm by eating raw or partly cooked fish. Infestation was common around the lakes of Scandinavia, Germany, Japan, North America, and Russia. Megaloblastic anemia or cobalamin neuropathy occurs only in those with a heavy infestation. Gluten-Induced Enteropathy  Malabsorption of cobalamin occurs in ∼30% of untreated patients (presumably those in whom the disease extends to the ileum). Cobalamin deficiency is not severe in these patients and is corrected with a gluten-free diet. Severe Chronic Pancreatitis  In this condition, lack of trypsin is thought to cause dietary cobalamin attached to gastric non-IF (HC) binder to be unavailable for absorption. It also has been proposed that, in pancreatitis, the concentration of calcium ions in the ileum falls below the level needed to maintain normal cobalamin absorption. HIV Infection  Serum cobalamin levels tend to fall in patients with HIV infection and are subnormal in 10–35% of those with AIDS. Mal­ absorption of cobalamin not corrected by IF has been shown in some, but not all, patients with subnormal serum cobalamin levels. Cobala­ min deficiency sufficiently severe to cause megaloblastic anemia or neuropathy is rare. Zollinger-Ellison Syndrome  Malabsorption of cobalamin has been reported in the Zollinger-Ellison syndrome. It is thought that there is a failure to release cobalamin from HC binding protein due to inactivation of pancreatic trypsin by high acidity, as well as interference with IF binding of cobalamin. Radiotherapy  Both total-body irradiation and local radiotherapy to the ileum (e.g., as a complication of radiotherapy for carcinoma of the cervix) may cause malabsorption of cobalamin. Graft-Versus-Host Disease  This commonly affects the small intestine. Malabsorption of cobalamin due to abnormal gut flora, as well as damage to ileal mucosa, is common. Drugs  The drugs that have been reported to cause malabsorption of cobalamin are listed in Table 104-4. However, megaloblastic anemia due to these drugs is rare. It has been suggested that metformin lowers serum cobalamin by lowering TC I level rather than causing malab­ sorption of cobalamin. ■ ■ABNORMALITIES OF COBALAMIN METABOLISM Congenital Transcobalamin II Deficiency or Abnormality  Infants with TC II deficiency usually present with megaloblastic anemia within a few weeks of birth. Serum cobalamin and folate levels are normal, but the anemia responds to massive (e.g., 1 mg three times weekly) injec­ tions of cobalamin. Some cases show neurologic complications. The pro­ tein may be present but functionally inert. Genetic abnormalities found include mutations of an intraexonic cryptic splice site, extensive deletion, single nucleotide deletion, nonsense mutation, and an RNA editing defect. Malabsorption of cobalamin occurs in all cases, and serum immunoglob­ ulins are usually reduced. Failure to institute adequate cobalamin therapy or treatment with folic acid may lead to irreversible neurologic damage. Congenital Methylmalonic Acidemia and Aciduria  Infants with this abnormality are ill from birth with vomiting, failure to thrive, severe metabolic acidosis, ketosis, and intellectual disability. Anemia, if present, is normocytic and normoblastic. The condition may be due to a functional defect in either mitochondrial methylmalonyl-CoA mutase or its cofactor adocobalamin. Mutations in the methylmal­ onyl-CoA mutase are not responsive or are only poorly responsive to treatment with cobalamin. A proportion of infants with failure of adocobalamin synthesis respond to cobalamin in large doses. Some children have combined methylmalonic aciduria and homocystinuria due to defective formation of both cobalamin coenzymes. This usually presents in the first year of life with feeding difficulties, developmental delay, microcephaly, seizures, hypotonia, and megaloblastic anemia. Acquired Abnormality of Cobalamin Metabolism: Nitrous Oxide Inhalation  Nitrous oxide (N2O) irreversibly oxidizes meth­ ylcobalamin to an inactive precursor; this inactivates methionine synthase. Megaloblastic anemia has occurred in patients undergoing prolonged N2O anesthesia (e.g., in intensive care units). A neuropathy resembling cobalamin neuropathy has been described in dentists and anesthetists who are exposed repeatedly to N2O. Methylmalonic acid­ uria does not occur as adocobalamin is not inactivated by N2O. CHAPTER 104 CAUSES OF FOLATE DEFICIENCY (Table 104-5) ■ ■NUTRITIONAL Dietary folate deficiency is common except in countries that fortify their diet with folic acid. In most patients with folate deficiency, a nutritional element is present. Certain individuals are particularly prone to have diets containing inadequate amounts of folate (Table 104-5). In the United States and other countries where fortification Megaloblastic Anemias TABLE 104-5  Causes of Folate Deficiency Dietarya   Particularly in: old age, infancy, poverty, alcoholism, chronic invalids, and the psychiatrically disturbed; may be associated with scurvy or kwashiorkor Malabsorption   Major causes of deficiency     Tropical sprue, gluten-induced enteropathy in children and adults, and in association with dermatitis herpetiformis, specific malabsorption of folate, intestinal megaloblastosis caused by severe cobalamin or folate deficiency   Minor causes of deficiency     Extensive jejunal resection, Crohn’s disease, partial gastrectomy, congestive heart failure, Whipple’s disease, scleroderma, amyloid, diabetic enteropathy, systemic bacterial infection, lymphoma, sulfasalazine (Salazopyrin) Excess utilization or loss   Physiologic     Pregnancy and lactation, prematurity   Pathologic     Hematologic diseases: chronic hemolytic anemias, sickle cell anemia, thalassemia major, myelofibrosis     Malignant diseases: carcinoma, lymphoma, leukemia, myeloma     Inflammatory diseases: tuberculosis, Crohn’s disease, psoriasis, exfoliative dermatitis, malaria     Metabolic disease: homocystinuria     Excess urinary loss: congestive heart failure, active liver disease     Hemodialysis, peritoneal dialysis Antifolate drugsb   Anticonvulsant drugs (phenytoin, primidone, barbiturates), sulfasalazine   Nitrofurantoin, tetracycline, antituberculosis (less well documented) Mixed causes   Liver diseases, alcoholism, intensive care units aIn severely folate-deficient patients with causes other than those listed under Dietary, poor dietary intake is often present. bDrugs inhibiting dihydrofolate reductase are discussed in the text. of the diet with folic acid has been adopted, the prevalence of folatedeficient megaloblastic anemia has dropped dramatically and is now restricted to high-risk groups with increased folate needs. Nutritional folate deficiency occurs in kwashiorkor and scurvy and in infants with repeated infections or those who are fed solely on goats’ milk, which has a low folate content. ■ ■MALABSORPTION Malabsorption of dietary folate occurs in tropical sprue and in gluteninduced enteropathy. In the rare congenital recessive syndrome of selec­ tive malabsorption of folate due to mutation of the PCFT, there is an associated defect of folate transport into the cerebrospinal fluid, and these patients show megaloblastic anemia, which responds to physiologic doses of folic acid given parenterally but not orally. They also show intellectual disability, convulsions, and other central nervous system abnormalities. Minor degrees of malabsorption may also occur after jejunal resection or partial gastrectomy, in Crohn’s disease, and in systemic infections, but in these conditions, if severe deficiency occurs, it is usually largely due to poor nutrition. Malabsorption of folate has been described in patients receiving sulfasalazine (Salazopyrin), cholestyramine, and triamterene. ■ ■EXCESS UTILIZATION OR LOSS Pregnancy  Folate requirements are increased by 50% daily in a normal pregnancy, partly because of transfer of the vitamin to the fetus but mainly because of increased folate catabolism due to cleavage of folate coenzymes in rapidly proliferating tissues. A dietary folate intake of 600 µg daily is recommended. Megaloblastic anemia due to folate deficiency is prevented by prophylactic folic acid therapy. It occurred in 0.5% of pregnancies in the UK and other Western countries before pro­ phylaxis with folic acid, but the incidence is much higher in countries where the general nutritional status is poor. During lactation, folate requirements are increased about 25 and a dietary intake of 500 µg of folate daily is advised. PART 4 Oncology and Hematology Prematurity  A newborn infant, whether full term or premature, has higher serum and red cell folate concentrations than an adult. However, a newborn infant’s demand for folate has been estimated to be up to 10 times that of adults on a weight basis, and the neonatal folate level falls rapidly to the lowest values at about 6 weeks of age. The falls are steepest and are liable to reach subnormal levels in premature babies, a number of whom develop megaloblastic anemia responsive to folic acid at about 4–6 weeks of age. This occurs particu­ larly in the smallest babies (<1500 g birth weight) and those who have feeding difficulties or infections or have undergone multiple exchange transfusions. In these babies, prophylactic folic acid should be given. Hematologic Disorders  Folate deficiency frequently occurs in chronic hemolytic anemias, particularly in sickle cell disease, autoim­ mune hemolytic anemia, and congenital spherocytosis. In these and in other conditions of increased cell turnover (e.g., myelofibrosis, malig­ nancies), folate deficiency arises because it is not completely reutilized after performing coenzyme functions. Inflammatory Conditions  Chronic inflammatory diseases such as tuberculosis, rheumatoid arthritis, Crohn’s disease, psoriasis, exfolia­ tive dermatitis, bacterial endocarditis, and chronic bacterial infections cause deficiency by reducing the appetite and increasing the demand for folate. Systemic infections also may cause malabsorption of folate. Severe deficiency is virtually confined to the patients with the most active disease and the poorest diet. Homocystinuria  This is a rare metabolic defect in the conversion of homocysteine to cystathionine. Folate deficiency occurring in most of these patients may be due to excessive utilization because of com­ pensatory increased conversion of homocysteine to methionine. Long-Term Dialysis  Because folate is only loosely bound to plasma proteins, it is easily removed from plasma by dialysis. In patients with anorexia, vomiting, infections, and hemolysis, folate stores are particularly likely to become depleted. Routine folate pro­ phylaxis is now given. Congestive Heart Failure and Liver Disease  Excess urinary folate losses of >100 μg per day may occur in some of these patients. It appears to be due to release of folate from damaged liver cells. ■ ■ANTIFOLATE DRUGS A large number of people with epilepsy receiving long-term therapy with phenytoin or primidone, with or without barbiturates, develop low serum and red cell folate levels. The exact mechanism is unclear. Alcohol may also be a folate antagonist, as patients who are drinking spirits may develop megaloblastic anemia that will respond to normal quantities of dietary folate or to physiologic doses of folic acid only if alcohol is withdrawn. Macrocytosis of red cells is associated with chronic alcohol intake even when folate levels are normal. Inadequate folate intake is the major factor in the development of deficiency in spirit-drinking alcoholics. Beer is relatively folate-rich in some coun­ tries, depending on the technique used for brewing. The drugs that inhibit DHF reductase include methotrexate, pyri­ methamine, and trimethoprim. Methotrexate has the most powerful action against the human enzyme, whereas trimethoprim is most active against the bacterial enzyme and is likely to cause megaloblastic ane­ mia only when used in conjunction with sulfamethoxazole in patients with preexisting folate or cobalamin deficiency. The activity of pyri­ methamine is intermediate. The antidote to these drugs is a reduced form of folate, folinic acid (5-formyl-THF). ■ ■CONGENITAL ABNORMALITIES OF FOLATE METABOLISM Some infants with congenital defects of folate enzymes (e.g., cyclohy­ drolase or methionine synthase) have had megaloblastic anemia. DIAGNOSIS OF COBALAMIN AND FOLATE DEFICIENCIES The diagnosis of cobalamin or folate deficiency has traditionally depended on the recognition of the relevant abnormalities in the peripheral blood and analysis of the blood levels of the vitamins. ■ ■COBALAMIN DEFICIENCY Serum Cobalamin  This is measured by an automated enzymelinked immunosorbent assay (ELISA) or competitive-binding lumi­ nescence assay (CBLA). Normal serum levels range from 118–148 pmol/L (160–200 ng/L) to ∼738 pmol/L (1000 ng/L). In patients with megaloblastic anemia due to cobalamin deficiency, the level is usually <74 pmol/L (100 ng/L). In general, the more severe the deficiency, the lower is the serum cobalamin level. In patients with spinal cord damage due to the deficiency, levels are very low even in the absence of anemia. Values between 74 and 148 pmol/L (100 and 200 ng/L) are regarded as borderline. They may occur, for instance, in pregnancy, in patients with megaloblastic anemia due to folate deficiency. They may also be due to heterozygous, homozygous, or compound heterozygous mutations of the gene TCN1 that codes for HC (TC I). There is then no clinical or hematologic abnormality. The serum cobalamin level is suf­ ficiently robust, cost-effective, and most convenient to rule out cobala­ min deficiency in the vast majority of patients suspected of having this problem. However, problems have arisen with commercial CBLA assays involving IF in PA patients with intrinsic antibodies in serum. These antibodies may cause false normal serum cobalamin levels in up to 50% of cases tested. Where clinical indications of PA are strong, a normal serum cobalamin does not rule out the diagnosis. Serum MMA levels will be elevated in untreated PA (see below). Folate deficiency, TC I (HC) deficiency, oral contraceptives, and multiple myeloma have all been associated with low serum cobalamin levels that do not indicate cobalamin deficiency. On the other hand, high serum cobalamin levels are usually due to raised serum TC I lev­ els and can be due to the presence of liver, renal, or myeloproliferative diseases or to cancer of the breast, colon, or liver. Serum Methylmalonate and Homocysteine  In patients with cobalamin deficiency sufficient to cause anemia or neuropathy, the serum MMA level is raised. Sensitive methods for measuring MMA and homocysteine in serum have been introduced and recommended for the early diagnosis of cobalamin deficiency, even in the absence of hematologic abnormalities or subnormal levels of serum cobalamin. Serum MMA levels fluctuate, however, in patients with renal failure. Mildly elevated serum MMA and/or homocysteine levels occur in up to 30% of apparently healthy volunteers, with serum cobalamin levels up to 258 pmol/L (350 ng/L) and normal serum folate levels; 15% of elderly subjects, even with cobalamin levels >258 pmol/L (>350 ng/L), have this pattern of raised metabolite levels. These findings bring into question the exact cutoff points for normal MMA and homocysteine levels. It is also unclear at present whether these mildly raised metabo­ lite levels have clinical consequences. Serum homocysteine is raised in both early cobalamin and folate deficiency but may be raised in other conditions, for example, chronic renal disease, alcoholism, smoking, pyridoxine deficiency, hypothy­ roidism, and therapy with steroids, cyclosporin, and other drugs. Levels are also higher in serum than in plasma, in men than in premenopausal women, in women taking hormone replacement therapy or in oral con­ traceptive users, and in elderly persons and patients with several inborn errors of metabolism affecting enzymes in trans-sulfuration pathways of homocysteine metabolism. Thus, homocysteine levels must be care­ fully interpreted for diagnosis of cobalamin or folate deficiency. Tests for the Cause of Cobalamin Deficiency  Only vegans, strict vegetarians, or people living on a totally inadequate diet will become cobalamin deficient because of inadequate intake. Studies of cobalamin absorption once were widely used, but difficulty in obtain­ ing radioactive cobalamin and ensuring that IF preparations are free of viruses has made these tests obsolete. Tests to diagnose PA include serum gastrin, which is raised; serum pepsinogen I, which is low in PA (90–92%) but also in other conditions; and gastric endoscopy. Tests for IF and parietal cell antibodies are also used, as well as tests for indi­ vidual intestinal diseases. Patients with atrophic gastritis may also have sufficient occult gas­ trointestinal blood loss to have iron deficiency as well as cobalamin deficiency. Iron deficiency may blunt the development of macrocytosis. Iron deficiency is much more common than cobalamin deficiency. In people older than age 60 years, cobalamin deficiency may accompany iron deficiency in 15–20% of cases. Thus, older patients diagnosed with iron-deficiency anemia should have cobalamin levels assessed, and those diagnosed with cobalamin deficiency should have their iron status assessed. ■ ■FOLATE DEFICIENCY Serum Folate  This is also measured by a chemiluminescence immu­ noassay or ELISA technique. In most laboratories, the normal range is from 11 nmol/L (2 μg/L) to ∼82 nmol/L (15 μg/L). The serum folate level is low in all folate-deficient patients. It also reflects recent diet. Because of this, serum folate may be low before there is hematologic or bio­ chemical evidence of deficiency. Serum folate rises in severe cobalamin deficiency because of the block in conversion of 5-MTHF to THF inside cells; raised levels have also been reported in the intestinal stagnant-loop syndrome due to absorption of bacterially synthesized folate. Red Cell Folate  The red cell folate assay is a valuable test of body folate stores. It is less affected than the serum assay by recent diet and traces of hemolysis. In normal adults, concentrations range from 880 to 3520 μmol/L (160–640 μg/L) of packed red cells. Subnormal levels occur in patients with megaloblastic anemia due to folate deficiency but also in nearly two-thirds of patients with severe cobalamin defi­ ciency. False-normal results may occur if a folate-deficient patient has received a recent blood transfusion or if a patient has a raised reticulo­ cyte count. Serum homocysteine assay is discussed earlier. Tests for the Cause of Folate Deficiency  The diet history is important. Tests for transglutaminase antibodies are performed to confirm or exclude gluten–induced enteropathy. If positive, duodenal biopsy is needed. An underlying disease causing increased folate break­ down should also be excluded. TREATMENT Cobalamin and Folate Deficiency It is usually possible to establish which of the two deficiencies, folate or cobalamin, is the cause of the anemia and to treat only with the appropriate vitamin. In patients who enter the hospital severely ill, however, it may be necessary to treat with both vitamins in large doses once blood samples have been taken for cobalamin and folate assays and a bone marrow biopsy has been performed (if deemed necessary). Transfusion is usually unnecessary and inadvisable. If it is essential, packed red cells should be given slowly, one or two units only, with the usual treatment for heart failure if present. Occasion­ ally, an excessive rise in platelets occurs after 1–2 weeks of therapy. Antiplatelet therapy, for example, aspirin, should be considered if the platelet count rises to >800 × 109/L. COBALAMIN DEFICIENCY It is usually necessary to treat patients who have developed severe cobalamin deficiency, as from PA, with lifelong regular cobalamin injections. In the UK, hydroxocobalamin is used; in the United States, cyanocobalamin. In a few instances, the under­ lying cause of cobalamin deficiency can be permanently corrected, for example, fish tapeworm, tropical sprue, or an intestinal stagnant loop that is amenable to surgery. The indications for starting cobal­ amin therapy are a well-documented megaloblastic anemia or other hematologic abnormalities and/or neuropathy due to the deficiency. Cobalamin should be given routinely to all patients who have had a total gastrectomy or ileal resection. Patients who have undergone gastric reduction for control of obesity or who are receiving longterm treatment with proton pump inhibitors should be screened and, if necessary, given cobalamin replacement. CHAPTER 104 Megaloblastic Anemias Replenishment of body stores should be complete with six 1000-μg IM injections of hydroxocobalamin given at 3- to 7-day intervals. More frequent doses are usually used in patients with cobalamin neuropathy, but there is no evidence that they produce a better response. Allergic reactions are rare and may require desensitiza­ tion or antihistamine or glucocorticoid cover. For maintenance therapy, 1000 μg hydroxocobalamin IM once every 3 months is sat­ isfactory. Because of the poorer retention of cyanocobalamin, pro­ tocols generally use higher and more frequent doses, for example, 1000 μg cyanocobalamin IM, monthly, for maintenance treatment. Because a small fraction of cobalamin can be absorbed passively through mucous membranes even when there is complete failure of physiologic IF-dependent absorption, large daily oral doses (1000– 2000 μg) of cyanocobalamin may be used in PA for replacement (especially in Canada and Sweden) and maintenance of normal cobalamin status. Sublingual therapy has also been proposed for those in whom injections are difficult because of a bleeding ten­ dency and who may not tolerate parenteral therapy. If oral therapy is used, it is important to monitor compliance, particularly with elderly, forgetful patients. This author prefers parenteral therapy for initial treatment for PA, particularly in severe anemia or if a neuropathy is present, and for maintenance. Treatment of patients with subnormal serum cobalamin levels with a normal MCV and no hypersegmentation of neutrophils and a negative IF antibody is, however, problematic. Some (perhaps 15%) cases may be due to TC I (HC) deficiency. Homocysteine and/ or MMA measurements may help, but in the absence of these tests and with otherwise normal gastrointestinal function, repeat serum cobalamin assay after 6–12 months may help one decide whether to start cobalamin therapy. Oral cyanocobalamin therapy with low doses (e.g., 50 μg daily) has a large role in treating patients thought to have food malabsorption of cobalamin. Cobalamin injections are used in a wide variety of diseases, often neurologic, despite normal serum cobalamin and folate levels and a normal blood count and in the absence of randomized, double-blind, controlled trials. These conditions include multiple sclerosis and chronic fatigue syndrome/myalgic encephalomyelitis (ME). It seems probable that any benefit is due to the placebo effect of a usually painless, pink injection. In ME, oral cobalamin therapy, despite pro­ viding equally large amounts of cobalamin, has not been beneficial, supporting the view of the effect of the injections being placebo only. FOLATE DEFICIENCY Oral doses of 5–15 mg of folic acid daily are satisfactory, as suf­ ficient folate is absorbed from these extremely large doses even in patients with severe malabsorption. The length of time therapy must be continued depends on the underlying disease. It is cus­ tomary to continue therapy for about 4 months, when all folatedeficient red cells will have been eliminated and replaced by new folate-replete populations. Before large doses of folic acid are given, cobalamin deficiency must be excluded and, if present, corrected; otherwise, cobalamin neuropathy may develop as the deficiency progresses despite a response of the anemia of cobalamin deficiency to folate therapy. Long-term folic acid therapy is required when the underlying cause of the deficiency cannot be corrected and the deficiency is likely to recur, for example, in chronic dialysis or chronic hemolytic anemias. It may also be necessary in gluten-induced enteropathy that does not respond to a gluten-free diet. Where mild but chronic folate deficiency occurs, it is preferable to encourage improvement in the diet after correcting the deficiency with a short course of folic acid. In any patient receiving long-term folic acid therapy, it is important to measure the serum cobalamin level at regular (e.g., once-yearly) inter­ vals to exclude the coincidental development of cobalamin deficiency. PART 4 Oncology and Hematology Folinic Acid (5-Formyl-THF)  This is a stable form of fully reduced folate. It is given orally or parenterally to overcome the toxic effects of methotrexate or other DHF reductase inhibitors, for example, trimethoprim or cotrimoxazole. PROPHYLACTIC FOLIC ACID Prophylactic folic acid is used in chronic dialysis patients and in par­ enteral feeds. Prophylactic folic acid has been used to reduce homo­ cysteine levels to prevent cardiovascular disease and for cognitive function in the elderly, but there are no firm data to show any benefit. Pregnancy  In over 80 countries (but none in Europe), food is for­ tified at a level of 120–250 µg/100 g with folic acid (in grain, flour, or rice) to reduce the risk of NTDs. In all countries that have studied this, fortification has led to a lower prevalence of NTD pregnancies and births. Nevertheless, folic acid, 400 μg daily, should also be given as a supplement before and throughout pregnancy to prevent mega­ loblastic anemia and reduce the incidence of NTDs, even in coun­ tries with fortification of the diet. Most if not all the folic acid used in fortification and eaten over three meals a day will be converted dur­ ing absorption to 5-MTHF. This compound at the levels achieved by fortification will not correct the anemia in cobalamin deficiency. Studies in the United States suggest that there is no increase in the proportion of individuals with low serum cobalamin levels and no anemia since food fortification with folic acid. It is unknown if there has been a change in incidence of cobalamin neuropathy, but no country has reported this since mandating fortification. Data in early pregnancy show significant lack of compliance with taking folic acid supplements, emphasizing the need for food fortification. In women who have had a previous fetus with an NTD and others at high risk (e.g., diabetes, sickle cell anemia), a dose of 5 mg daily is recommended when pregnancy is contemplated and throughout the subsequent pregnancy. Infancy and Childhood  The incidence of folate deficiency is so high in the smallest premature babies during the first 6 weeks of life that folic acid (e.g., 1 mg daily) should be given routinely to those weighing <1500 g at birth and to larger premature babies who require exchange transfusions or develop feeding difficulties, infec­ tions, or vomiting and diarrhea. The World Health Organization currently recommends routine supplementation with iron and folic acid in children in countries where iron deficiency is common and child mortality, largely due to infectious diseases, is high. However, some studies suggest that in areas where malaria rates are high, this approach may increase the incidence of severe illness and death. Even where malaria is rare, there appears to be no survival benefit. MEGALOBLASTIC ANEMIA NOT DUE TO COBALAMIN OR FOLATE DEFICIENCY OR ALTERED METABOLISM This may occur with many antimetabolite drugs (e.g., hydroxyurea, cytarabine, mercaptopurine, thioguanine) that inhibit DNA replica­ tion. Antiviral nucleoside analogues used in treatment of HIV infec­ tion may also cause macrocytosis and megaloblastic marrow changes. In the rare disease orotic aciduria, two consecutive enzymes in purine synthesis are defective. The condition responds to therapy with uridine, which bypasses the block. In thiamine-responsive megaloblastic ane­ mia, there is a genetic defect in the high-affinity thiamine transporter (SLC19A2) gene. This causes defective RNA ribose synthesis through impaired activity of transketolase, a thiamine-dependent enzyme in the pentose cycle. This defect leads to reduced nucleic acid production. It may be associated with diabetes mellitus and deafness and the presence of many ringed sideroblasts in the marrow. The explanation is unclear for megaloblastic changes in the marrow in some patients with acute myeloid leukemia and myelodysplasia. The most frequent causes of macrocytosis without megaloblastic changes are alcohol, liver disease, hypothyroidism, and pregnancy. Myelodysplasia, myeloma and other paraproteinemias, aplastic ane­ mia, and smoking are other causes. ■ ■FURTHER READING Berry RJ: Lack of historical evidence to support folic acid exacerbation of the neuropathy caused by vitamin B12 deficiency. Am J Clin Nutr 110:554, 2019. Bunn HF: Vitamin B12 and pernicious anemia: The dawn of molecular medicine. N Engl J Med 370:773, 2014. Del Bo C et al: Effect of two different sublingual dosages of vitamin B12 on cobalamin nutritional status in vegans and vegetarians with a marginal deficiency: A randomized controlled trial. Clin Nutr 38:575, 2019. Green R: Vitamin B12 deficiency from the perspective of a practicing hematologist. Blood 129:2603, 2017. Green R et al: Vitamin B12 deficiency. Nat Rev Dis Primers 3:17040, 2017. Hesdorffer CS, Longo DL: Drug-induced megaloblastic anemia. N Engl J Med 373:1649, 2015. Hoffbrand V: The Folate Story: A Vitamin Under the Microscope. Leicestershire, UK, Troubador Publishing, 2023. Kancherla V et al: Preventing birth defects, saving lives, and promot­ ing health equity: An urgent call to action for universal mandatory food fortification with folic acid. Lancet Global Health 10:e1053, 2022. Ma F et al: Effects of folic acid and vitamin B12 alone and in combina­ tion on cognitive function and inflammatory factors in the elderly with mild cognitive impairment: A single blind experimental design. Curr Alzheimer Res 16:622, 2019. Miller JW: Proton pump inhibitors, H2-receptor antagonists, metfor­ min, and vitamin B-12 deficiency: Clinical implications. Adv Nutr 9:511S, 2018. O’connor DMA et al: Low folate predicts cognitive decline: 8-year fol­ low–up of 3140 older adults in Ireland. Eur J Clin Nutr 76:950, 2022. Rogers LM et al: Global folate status in women of reproductive age: A systematic review with emphasis on methodological issues. Ann N Y Acad Sci 1431:35, 2018. Salinas M et al: High frequency of anti-parietal cell antibody (APCA) and intrinsic factor blocking antibody (IFBA) in individuals with severe vitamin B12 deficiency: An observational study in primary care patients. Clin Chem Lab Med 58:424, 2020. Wald NJ: Folic acid and neural tube defects: Discovery, debate and the need for policy change. J Med Screening 29:138, 2022. Zaric BL et al: Homocysteine and hyperhomocysteinaemia. Curr Med Chem 26: 2948, 2019. # 35 - 105 Hemolytic Anemias ### 105 Hemolytic Anemias Lucio Luzzatto, Lucia De Franceschi Hemolytic Anemias ■ ■DEFINITIONS Turnover is typical of all blood cells, including erythrocytes, that have a finite life span. Hence, a logical, time-honored classification of anemias is in three groups: (1) decreased production of red cells, (2) increased destruction of red cells, and (3) acute blood loss. Decreased production is covered in Chaps. 102, 103, and 107; acute blood loss in Chap. 106; increased destruction is covered in this chapter. All patients who are anemic as a result of either increased destruc­ tion of red cells or acute blood loss have one important element in common: the anemia results from overconsumption of red cells from the peripheral blood, whereas the supply of cells from the bone marrow is normal (indeed, it is usually increased). However, with blood loss, as in acute hemorrhage, the red cells are physically lost from the body itself; this is fundamentally different from destruction of red cells within the body, as in hemolytic anemias (HAs). With respect to primary etiology, HAs may be inherited or acquired; from a clinical point of view, they may be more acute or more chronic, and they may vary from mild to very severe; the site of hemolysis may be predominantly intravascular or extravascular. With respect to mech­ anisms, HAs may be due to intracorpuscular causes or to extracorpus­ cular causes (Table 105-1). But before reviewing the individual types of HA, it is appropriate to consider what general features they have in common, in terms of clinical aspects and pathophysiology. ■ ■GENERAL CLINICAL AND LABORATORY FEATURES The clinical presentation of a patient with anemia is greatly influenced in the first place by whether the onset is abrupt or gradual, and HAs are no exception. A patient with autoimmune HA or with favism may be a medical emergency, whereas a patient with mild hereditary sphero­ cytosis (HS) or with cold agglutinin disease (CAD) may be diagnosed after years. This is due in large measure to the remarkable ability of the body to adapt to anemia when it is slowly progressing (Chap. 66). What differentiates HAs from other anemias is that the patient has signs and symptoms arising directly from hemolysis (Table 105-2). At the clinical level, the main sign is jaundice; in addition, the patient may report discoloration of the urine. In many cases of HA, the spleen is enlarged because it is a preferential site of hemolysis; in some cases, the liver may be enlarged as well; and gallstones are common. In all severe congenital forms of HA, there may also be skeletal changes due to over­ activity of the bone marrow: they are never as severe as in thalassemia TABLE 105-1  Classification of Hemolytic Anemiasa EXTRACORPUSCULAR FACTORS   INTRACORPUSCULAR DEFECTS Inherited Hemoglobinopathies Enzymopathies Membrane-cytoskeletal defects Familial (atypical) hemolyticuremic syndrome Acquired Paroxysmal nocturnal hemoglobinuria (PNH) Mechanical destruction (microangiopathic) Toxic agents Drugs Infectious Autoimmune aHereditary causes correlate with intracorpuscular defects because these defects are due to inherited mutations; the one exception is PNH because the defect is due to an acquired somatic mutation. Conversely, acquired causes correlate with extracorpuscular factors because mostly these factors are exogenous; the one exception is familial hemolytic-uremic syndrome (HUS; often referred to as atypical HUS [aHUS]) because here an inherited abnormality permits complement activation triggered by exogenous factors to become excessive, with bouts of production of membrane attack complex capable of destroying normal red cells. Interestingly, in both PNH and aHUS, hemolysis is complement-mediated. TABLE 105-2  Features Common to Most Patients with a Hemolytic Disorder GENERAL EXAMINATION JAUNDICE, PALLOR Other physical findings Spleen may be enlarged; bossing of skull in severe congenital cases Hemoglobin level From normal to severely reduced MCV, MCH Usually increased Reticulocytes Usually increased Bilirubin Almost always increased (mostly unconjugated) LDH Increased (up to 10× normal with intravascular hemolysis) Haptoglobin Reduced to absent if hemolysis is at least in part intravascular Abbreviations: LDH, lactate dehydrogenase; MCH, mean corpuscular hemoglobin; MCV, mean corpuscular volume. major because ineffective erythropoiesis is less, or even absent. Since several forms of HA are inherited, it is important to include family his­ tory in the initial appraisal. The laboratory features of HA are related to (1) hemolysis per se and (2) the erythropoietic response of the bone marrow. In most cases, hemolysis is largely extravascular, and it produces an increase in unconjugated bilirubin and aspartate aminotransferase (AST) in the serum; urobilinogen will be increased in both urine and stool. If hemolysis is mainly intravascular, the telltale sign is hemoglobinuria (often associated with hemosiderinuria); in the serum, there is free hemoglobin, lactate dehydrogenase (LDH) is increased, and haptoglo­ bin is reduced. In contrast, the serum bilirubin level may be normal or only mildly elevated. The main sign of the erythropoietic response by the bone marrow is an increase in reticulocytes (a test all too often neglected in the initial workup of a patient with anemia). Usually the increase will be reflected in both the percentage of reticulocytes (the more commonly quoted figure) and in the absolute reticulocyte count (the more definitive parameter). The increased number of reticulocytes is associated with an increased mean corpuscular volume (MCV) in the blood count. On the blood smear, this is reflected in the presence of macrocytes; polychromasia is also present, and sometimes one sees nucleated red cells. In most cases, a bone marrow aspirate is not necessary in the diagnostic workup; if it is done, it will show erythroid hyperplasia. In practice, once an HA is suspected, specific tests will usually be required for a definitive diagnosis of a specific type of HA. CHAPTER 105 Hemolytic Anemias ■ ■GENERAL PATHOPHYSIOLOGY The mature red cell is the product of a developmental pathway that brings the phenomenon of differentiation to an extreme. An orderly sequence of events produces synchronous changes, whereby the gradual accumulation of a huge amount of hemoglobin in the cyto­ plasm (to a final level of 340 g/L, i.e., about 5 mM) goes hand in hand with the gradual loss of cellular organelles and of biosynthetic abilities. In the end, the erythroid cell undergoes a process that has features of apoptosis, including nuclear pyknosis and eventually extrusion of the nucleus. However, the final result is more altruistic than suicidal; the cytoplasmic body, instead of disintegrating, is now able to provide oxy­ gen to all cells in the human organism for some remaining 120 days of the red cell life span. As a result of this unique process of differentiation and maturation, intermediary metabolism is drastically curtailed in mature red cells (Fig. 105-1); for instance, cytochrome-mediated oxidative phosphory­ lation has been lost with the loss of mitochondria (through a process of physiologic autophagy); therefore, there is no backup to anaerobic glycolysis, which in the red cell is the only provider of adenosine tri­ phosphate (ATP). Also, the capacity of making protein has been lost with the loss of ribosomes. This places the cell’s limited metabolic apparatus at risk, because if any protein component deteriorates, it cannot be replaced, as it would be in most other cells; and in fact, the activity of most enzymes gradually decreases as red cells age. At the same time, during their long time in circulation, various red cell Embden-Meyerhof pathway Hexose monophosphate shunt Glutathione reductase GSH GSSG glucose hexokinase ATP NADPH NADP+ ADP glucose-6-phosphate 6-phosphogluconate G6PD glucose phosphate isomerase fructose-6-phosphate ATP ADP phosphofructokinase fructose-1, 6-diphosphate aldolase glyceraldehyde-3-phosphate NAD+ glyceraldehyde 3-phosphate dehydrogenase HbFe2+ NADH HbFe3+ 2,3-bisphosphoglycerate mutase 1,3-bisphosphoglycerate ADP phosphoglycerate kinase 2,3-bisphosphoglycerate ATP 2,3-bisphosphoglycerate phosphatase 3-phosphoglycerate PART 4 Oncology and Hematology 3-phosphoglycerate mutase 2-phosphoglycerate enolase phosphoenolpyruvate pyruvate kinase ADP ATP pyruvate NADH lactate dehydrogenase NAD+ lactate FIGURE 105-1  Red blood cell (RBC) metabolism. The Embden-Meyerhof pathway (glycolysis) generates ATP required for cation transport and for membrane maintenance. The generation of NADH maintains hemoglobin iron in a reduced state. The hexose monophosphate shunt generates NADPH that is used to reduce glutathione, which protects the red cell against oxidant stress; the 6-phosphogluconate, after decarboxylation, can be recycled via pentose sugars to glycolysis. Regulation of the 2,3-bisphosphoglycerate level is a critical determinant of oxygen affinity of hemoglobin. Enzyme deficiency states in order of prevalence: glucose-6-phosphate dehydrogenase (G6PD) > pyruvate kinase > glucose-6phosphate isomerase > rare deficiencies of other enzymes in the pathway. The more common enzyme deficiencies are encircled. components inevitably accumulate damage and become physically denser. The anion exchanger known as band 3 is the most abundant pro­ tein in the red cell membrane (Fig. 105-2 and Table 105-3), with about 1.2 million molecules per red cell. As red cells age and become denser, probability is increased that a region of the band 3 molecule becomes exposed on the cell surface and contributes to creating an antigenic site recognizable by low-avidity naturally occurring anti–band 3 IgG antibodies. This process might be enhanced by the clustering of band 3 molecules favored by the antibody itself and by the binding of hemichromes arising from hemoglobin degradation. Senescent red cells thus become opsonized, and this is the signal for phagocytosis by macrophages in the spleen, in the liver, and elsewhere. This process may become accelerated in various ways in HA. Another consequence of the relative simplicity of red cells is that they have a limited range of ways to manifest distress under hardship; in essence, any sort of metabolic failure will eventually lead either to structural damage to the membrane or to failure of the cation pump. In either case, the life span of the red cell is reduced, which is the defini­ tion of a hemolytic disorder. If the rate of red cell destruction exceeds the capacity of the bone marrow to produce more red cells, the hemo­ lytic disorder will manifest as HA. Thus, the essential pathophysiologic process common to all HAs is an increased red cell turnover; in many HAs, this is due at least in part to an acceleration of the senescence process described above. The gold standard for proving that the life span of red cells is reduced (compared to the normal value of ~120 days) is a red cell survival study, which can be carried out by labeling the red cells with 51Cr and measuring the fall in radioactivity over several days or weeks (this classic test can now be replaced by a methodology using the nonradioactive isotope 15N). If the hemolytic event is transient, it does not usually cause any long-term consequences, except for an increased requirement for erythropoietic factors, particularly folic acid. However, if hemolysis is recurrent or persistent, the increased bilirubin production favors the formation of gallstones. If a considerable proportion of hemolysis takes place in the spleen, as is often the case, splenomegaly may become increasingly a feature, and hypersplenism may develop, with consequent neutropenia and/or thrombocytopenia. The increased red cell turnover has important consequences. In nor­ mal subjects, the iron from effete red cells is very efficiently recycled by the body; however, with chronic intravascular hemolysis, the persistent hemoglobinuria will cause considerable iron loss, needing replace­ ment. With chronic extravascular hemolysis, the opposite problem, iron overload, is more common, especially if the patient needs frequent blood transfusions. Even without blood transfusion, when erythropoi­ esis is massively increased, the release of erythroferrone from erythroid cells suppresses hepcidin, causing increased iron absorption. In the long run, in the absence of iron-chelation therapy, iron overload will cause secondary hemochromatosis; this will cause damage particularly to the liver, eventually leading to cirrhosis, and to the heart muscle, eventually causing heart failure. Compensated Hemolysis versus Hemolytic Anemia  Red cell destruction is a potent stimulus for erythropoiesis, which is mediated by erythropoietin (EPO) produced by the kidney. This mechanism is so effective that in many cases the increased output of red cells from the bone marrow can fully balance an increased destruction of red cells. In such cases, we say that hemolysis is compensated. The pathophysiology of compensated hemolysis is similar to what we have just described, except there is no anemia. This notion is important from the diagnostic point of view, because a patient with a hemolytic condition, even an inherited one, may present without anemia; and it is also important from the point of view of management because compensated hemolysis may become “decompensated,” i.e., anemia may suddenly appear in certain circum­ stances, for instance in pregnancy, folate deficiency, or renal failure inter­ fering with adequate EPO production. Another general feature of chronic HAs is seen when any intercurrent condition, such as an acute infection, depresses erythropoiesis. When this happens, in view of the increased rate of red cell turnover, the effect will be predictably much more marked than in a person who does not have hemolysis. The most dramatic example is infection by parvovirus B19, which may cause a rather precipitous fall in hemoglobin—an occurrence sometimes referred to as aplastic crisis. ■ ■INHERITED HEMOLYTIC ANEMIAS The red cell has three essential components: (1) hemoglobin, (2) the membrane-cytoskeleton complex, and (3) the metabolic machinery necessary to keep hemoglobin and the membrane-cytoskeleton com­ plex in working order. Diseases caused by inherited abnormalities of hemoglobin, or hemoglobinopathies, are covered in Chap. 103. Here we will deal with diseases of the other two components. Hemolytic Anemias due to Abnormalities of the MembraneCytoskeleton Complex  The detailed architecture of the red cell membrane is complex, but its basic design is relatively simple (Fig. 105-2). The lipid bilayer incorporates phospholipids and cholesterol, and it is spanned by a number of proteins that have their hydrophobic transmembrane domain(s) embedded in the membrane; most of these proteins also extend to both the outside (extracellular domains) and the inside of the cell (cytoplasmic domains). Other proteins are teth­ ered to the membrane through a glycosylphosphatidylinositol (GPI) anchor; these have only an extracellular domain. Membrane proteins include energy-dependent ion transporters, ion channels, receptors Ankyrin complex RhAG AChE CD59 Rh KCNN4 ABCB6 Band 3 Band 3 CD47 PIEZO1 4.2 GPA Adducin -Spectrin 4.1R Ankyrin -Spectrin Tropomyosin Self-association site PIEZO1 KCNN4 ABCB6 Glut1 Band 3 HCO3 – Cl– Na+ K+ Ca2+ Glucose FIGURE 105-2  The red cell membrane and cytoskeleton schematic diagram. Within the membrane lipid bilayer, several integral membrane proteins are shown (see inset). Other proteins, e.g., acetylcholinesterase (AChE) and the two complement-regulatory proteins CD59 and CD55, are tethered to the membrane through the glycosylphosphatidylinositol (GPI) anchor: in these cases, the entire polypeptide chain is extracellular. Many of the membrane proteins bear polypeptide and/or carbohydrate red cell antigens. Underneath the membrane, the α-β spectrin dimers, which associate head-to-head into tetramers, together with actin and other proteins, form most of the cytoskeleton. The ankyrin complex, which also involves the band 4.2 protein, and the junctional complex, which involves the band 4.1 protein and dematin, connect the membrane to the cytoskeleton. The ankyrin complex provides mainly radial (also called vertical) connections; the junctional complex provides mainly tangential (also called horizontal) connections. Pathogenic changes in the former can cause spherocytosis, whereas pathogenic changes in the latter can cause elliptocytosis; pathogenic changes in spectrin can cause either. Branched lines symbolize carbohydrate moiety of proteins. The various molecules are obviously not drawn to the same scale. Inset. Schematic diagram of membrane transporters, abnormalities of which underlie channelopathies. Band 3 (anion exchanger 1 [AE1]) is the most abundant. Mutations of SLC4A1 (encoding band 3) can inactivate anion exchange, causing cation leak or negatively affecting interactions with neighboring membrane proteins. PIEZO1 is a huge protein that is embedded in the membrane as a homo-trimer with a three-bladed, propeller-shaped structure; it is a mechano-sensitive cation channel. KCNN4 encodes a Ca2+ activated K+ channel, also known as the Gardos channel. PIEZO1 mutations can be associated with abnormal Ca2+ entry, resulting in overactivation of the Gardos channel; this promotes K+ efflux and red cell dehydration Mutations on KCC4 induce alterations of channel properties (kinetic or ion trafficking), resulting again in abnormal K+ efflux and red cell dehydration. ABCB6 encodes a mitochondrial porphyrin transporter, but some mutations can cause increased K+ efflux from red cells and stomatocytosis. Glut1 facilitates glucose transport; it is encoded by SLC2A1, and mutations can block the glucose transport and induce Na+, K+ leakage. (Modified from N Young et al: Clinical Hematology. Philadelphia, Elsevier, 2006; and from A Iolascon et al: Br J Haematol 187:13, 2019.) for complement components, and receptors for other ligands. The most abundant red cell membrane proteins are glycophorins and the so-called band 3, an anion transporter that is an integral membrane protein. The extracellular domains of many of these proteins are heav­ ily glycosylated, and they carry antigenic determinants that correspond to blood groups. Underneath the membrane, and tangential to it, is a network of other proteins that make up the cytoskeleton. The main cytoskeletal protein is the spectrin tetramer, consisting of a headto-head association of two α-spectrin-β-spectrin heterodimers. The cytoskeleton is linked to the membrane through the ankyrin complex (that includes also band 4.2) and the junctional complex (that includes adducin and band 4.1) (Fig. 105-2). These multiprotein complexes make membrane and cytoskeleton intimately connected to each other, thus supporting membrane stability and at the same time providing the erythrocyte with the important property of deformability. The membrane-cytoskeleton complex has essentially three functions: it is an envelope for the red cell cytoplasm; it maintains the normal red cell shape; and it provides cross-membrane trans­ port of electrolytes and of metabolites such as glucose and amino acids. In the membrane-cytoskeleton complex, the individual components are so inti­ mately associated with each other that an abnormality of almost any of them will be disturbing or disruptive, causing mechanical instability of the membrane and/or reduced red cell deformability, ultimately causing hemolysis. These abnormalities are almost invariably inherited mutations; thus, diseases of the membrane-cytoskeleton complex belong to the category of inherited HAs. Before the red cells lyse, they often exhibit more or less specific changes that alter the normal biconcave disk shape. Thus, the majority of the diseases in this group have been known for over a century as hereditary spherocytosis (HS) and hereditary elliptocytosis (HE). More recently, a third morphologic entity, whereby on a blood smear the roundshaped central pallor of a red cell is replaced by a linear-shaped central pale area, has earned the name stomatocytosis; because this abnormal shape is related to abnormalities of channel molecules, the underlying disorders are also referred to as channelopathies. From an under­ standing of the molecular basis of these disorders, it has emerged (Table 105-3) that, although these disorders are pre­ dominantly monogenic, no one-to-one correlation exists between a certain gene and a certain disorder. Rather, what has been regarded as a single disorder (e.g., HS) can arise through mutation of one of several genes; conversely, what have been regarded as different disorders can arise through different mutations of the very same gene (Fig. 105-3). Junctional complex CD55 GPC Glut1 p55 Dematin Actin protofilament Tropomodulin CHAPTER 105 Hemolytic Anemias HEREDITARY SPHEROCYTOSIS  This is most common among this group of HAs, with an estimated prevalence of 1:2000–1:5000 in populations of European ancestry. Its identification is credited to Minkowksy and Chauffard, who, at the end of the nineteenth century, reported families who had spherocytes in their peripheral blood (Fig. 105-4A). In vitro studies revealed that the red cells were abnormally susceptible to lysis in hypotonic media; indeed, the increase in osmotic fragility became the main diagnostic test for HS. Today we know that HS, thus defined, is genetically heterogeneous; i.e., it can arise from a variety of mutations in one of several genes (Table 105-3). It has been also recognized that the inheritance of HS is not always autosomal domi­ nant (with the patient being heterozygous); indeed, some of the most severe forms are instead autosomal recessive (with the patient being homozygous). Clinical Presentation and Diagnosis  The spectrum of clinical severity of HS is broad. Severe cases may present in infancy with severe anemia, whereas mild cases may present in young adults or even later in life. The main clinical findings are jaundice, an enlarged spleen, and often gallstones; indeed, it may be the finding of gallstones in a young person that triggers diagnostic investigations. TABLE 105-3  Inherited Diseases of the Red Cell Membrane-Cytoskeleton Complex CHROMOSOMAL LOCATION PROTEIN PRODUCED DISEASE(S) WITH CERTAIN MUTATIONS (INHERITANCE) COMMENTS GENE SPTA1 1q22-q23 α-Spectrin HS (recessive) Rare       HE (dominant) Mutations of this gene account for about 65% of HE. More severe forms may be due to coexistence of an otherwise silent mutant allele. SPTB 14q23-q24.1 β-Spectrin HS (dominant) Rare       HE (dominant) Mutations of this gene account for about 30% of HE, including some severe forms. ANK1 8p11.2 Ankyrin HS (dominant) May account for majority of HS. SLC4A1 17q21 Band 3; also known as AE (anion exchanger) or AE1 HS (dominant) Mutations of this gene may account for about 25% of HS. Southeast Asia ovalocytosis (dominant) Stomatocytosis (cryohydrocytosis) EPB41 1p33-p34.2 Band 4.1 HE (dominant) Mutations of this gene account for about 5% of HE, mostly with prominent morphology but little/no hemolysis in heterozygotes; severe hemolysis in homozygotes. EPB42 15q15-q21 Band 4.2 HS (recessive) Mutations of this gene account for about 3% of HS. RHAG 6p21.1-p11 Rhesus-associated glycoprotein Chronic nonspherocytic hemolytic anemia (recessive) PART 4 Oncology and Hematology PIEZO1 16q23-q24 PIEZO1 (mechanosensitive ion channel component 1 channel) Dehydrated hereditary stomatocytosis (dominant) KCNN4 19q13.31 KCNN4 Intermediate conductance calcium-activated potassium channel protein 4 (Gardos channel) Dehydrated hereditary stomatocytosis (dominant) ABCB6 2q35-q36 ATP-binding cassette subfamily B member 6 Familial pseudohyperkalemia (dominant) SLC2A1 1p34.2 GLUT1 glucose transporter Overhydrated hereditary stomatocytosis Note: PIEZO1, KCNN4, ABCB6, and GLUT1 are channel molecules; conditions associated with mutations in the respective genes are appropriately named channelopathies. Abbreviations: HE, hereditary elliptocytosis; HS, hereditary spherocytosis. The variability in clinical manifestations that is observed among patients with HS is largely due to the different underlying molecular lesions (Table 105-3). Not only are mutations of several genes involved, ANK1 EPB42 HS SPTA1 SPTB SLC4A1 EPB41 HE SLC2A1 RHAG PIEZ01 HSt KCNN4 ABCB6 FIGURE 105-3  Hereditary spherocytosis (HS), hereditary elliptocytosis (HE), and hereditary stomatocytosis (HSt) are three morphologically distinct forms of congenital hemolytic anemia. It has emerged that each one can arise from mutation of one of several genes and that different mutations of the same gene can give one or another form. (See also Table 105-3.) Genes encoding membrane proteins are in black; genes encoding cytoskeleton proteins are in green; genes encoding proteins in the junctional and ankyrin complexes are in purple. Polymorphic mutation (deletion of nine amino acids); in heterozygotes, clinically asymptomatic and protective against Plasmodium falciparum. Certain specific missense mutations shift protein function from anion exchanger to cation conductance. Very rare; associated with total loss of all Rh antigens. One specific mutation in this gene entails loss of stomatin from the cell membrane, causing overhydrated stomatocytosis. Also known as xerocytosis with pseudohyperkalemia. Patients may present with perinatal edema. Clinical presentation similar to that of PIEZO1 mutants. Increased potassium leakage upon storage in blood bank condition: this can cause hyperkalemia in the recipient. ABCB6 mutation is present in 0.3% of blood donors. Associated with serious neurologic manifestations. but also different mutations of the same gene can give very different clinical manifestations. In milder cases, hemolysis is often compen­ sated (see above), but changes in clinical expression may be seen even in the same patient because intercurrent conditions (e.g., pregnancy, infection) may cause decompensation. The anemia is usually nor­ mocytic with the characteristic morphology that gives the disease its name. An increased mean corpuscular hemoglobin concentration (MCHC >34 g/dL) and increased red cell distribution width (RDW >14%) associated with normal or slightly decreased MCV on an ordinary blood count report should raise the suspicion of HS. The spleen plays a key role in HS through a dual mechanism. On one hand, because HS red cells are less deformable, transit through the splenic circulation makes them more prone to vesiculate; on the other hand, like in many other HAs, the spleen itself is a major site of destruction through phagocytosis by macrophages. When there is a family history, it is usually easy to make a diagnosis based on features of HA and typical red cell morphology. However, fam­ ily history may be negative for at least two reasons. First, the patient may have a de novo mutation, i.e., a mutation that has taken place in a germ cell of one of the patient’s parents or early after zygote formation. Second, the patient may have a recessive form of HS (Table 105-3). In such cases, more extensive laboratory investigations are required, including osmotic fragility, the acid glycerol lysis test, the eosin-5′-maleimide (EMA)–bind­ ing test, sodium dodecyl sulfate (SDS)-gel electrophoresis of membrane proteins, and ektacytometry (testing red cell deformability as a function of shear stress at different osmolality); these tests are usually carried out in laboratories with special expertise in this area. Sometimes a definitive diagnosis can be obtained only by molecular studies demonstrating a mutation in one of the genes underlying HS (Table 105-3). TREATMENT Hereditary Spherocytosis We do not have a causal treatment for HS; i.e., no way has yet been found to correct the basic defect in the membrane-cytoskeleton structure. Given the special role of the spleen in HS (see above), sple­ nectomy is often beneficial. Current recommendations are to proceed with splenectomy at the age of 4–6 years in severe cases, to delay sple­ nectomy until puberty in moderate cases, and to avoid splenectomy in mild cases. Partial splenectomy can be considered in certain cases, and it is helpful to know about the outcome of splenectomy in the patient’s affected relatives. Before splenectomy, vaccination against encapsulated bacteria (Neisseria meningitidis and Streptococcus pneu­ moniae) is imperative; penicillin prophylaxis after splenectomy is controversial. Along with splenectomy, cholecystectomy should not be carried out automatically, but it should be carried out, usually by the laparoscopic approach, whenever it is clinically indicated, mainly when gallstones are symptomatic. The most severe cases of HS (esti­ mated at <10%) are transfusion dependent, and in infants with severe HS, erythropoietin may prove to be transfusion sparing. HEREDITARY ELLIPTOCYTOSIS  HE is at least as heterogeneous as HS, both from the genetic point of view (Table 105-3, Fig. 105-3) and from the clinical point of view. The global incidence of HE is 1:2000–4000 subjects. Again, it is the shape of the red cells (Fig. 105-4B) that gives the name to the condition, but there is no direct correlation between the elliptocytic morphology and clinical severity. In fact, some mild or even asymptomatic cases may have nearly 100% elliptocytes (or ovalo­ cytes). Indeed, the diagnosis of HE is generally incidental, because hemolysis may be compensated and there may be no anemia, although this may become evident in the course of infection. One particular in-frame deletion of nine amino acids in the SLC4A1 gene encoding band 3 underlies the so-called Southeast Asia ovalocytosis (SAO): it is not a disease, but rather a polymorphism with a frequency of up to 5–7% in certain populations (e.g., Papua New Guinea, Indonesia, Malaysia, Philippines), presumably as a result of malaria selection. It is asymptomatic in heterozygotes and probably lethal in homozygotes. The cases of HE with the most severe HA are those with biallelic muta­ tions of one of the genes involved (see Fig. 105-3), and these are said to have hereditary pyropoikilocytosis (HPP): here the instability of the cytoskeleton protein network may result from decreased tetrameriza­ tion of spectrin dimers. The red cell volume is decreased (MCV: 50–60 fL), and all kinds of bizarre poikilocytes are seen on the blood smear (Fig. 105-4C). HPP patients have splenomegaly and often ben­ efit from splenectomy. Channelopathies  These rare conditions (see Fig. 105-3) are char­ acterized by abnormalities in red cell ion content and alteration of erythrocyte volume. Cation leak can cause hyperkalemia; in some cases, this leak is accelerated in the cold (the resulting spuriously high serum K+ is then referred to as pseudo-hyperkalemia). The less rare form, dehydrated stomatocytosis (DHS; also referred to as xerocyto­ sis), is a (usually compensated) macrocytic hemolytic disorder, with increased MCHC (generally >36 g/dL) associated with mild jaundice. Mutations in either PIEZO1, encoding an ion channel activated by pressure (mechanoreceptor), or in KCCN4, encoding the Ca2+ activated K+ channel (Gardos channel) have been recognized to cause DHS (see Table 105-3). Another form is overhydrated stomatocytosis (OHS). OHS is also macrocytic (MCV >110 fL), but the MCHC is low (<30 g/dL). The underlying mutation is in the Rhesus gene RHAG, which encodes an ammonia channel. Yet other patients with stomatocytosis (Table 105-3) have mutations in SLC4A1 (encoding band 3) and SLC2A1 (encoding the glucose transporter GLUT1). Mutations of the latter are responsible for cryohydrocytosis, a channelopathy in which the red cells swell and burst when they are cooled. In vivo hemolysis can vary from relatively mild to quite severe. Familial hyperkalemia has been recently linked to mutations in ABCB6, resulting in abnormal cation leak with extra­ cellular release of a large amount of K+ (hyperkalemia). Mutations in A CHAPTER 105 Hemolytic Anemias B C FIGURE 105-4  Peripheral blood smear from patients with membrane-cytoskeleton abnormalities. A. Hereditary spherocytosis. B. Hereditary elliptocytosis, heterozygote. C. Pyropoikilocytosis, with both alleles of the α-spectrin gene mutated. ABCB6 have been identified in almost 0.3% of blood donors. However, splenectomy is contraindicated in stomatocytosis due to the significant proportion of severe thromboembolic complications observed in sple­ nectomized DHS patients. Laser diffraction analysis, or ektacytometry, can measure the deformability of red blood cells subjected to either increasing shear stress or to an osmotic stress. This technique has been used extensively to investigate membrane-cytoskeleton abnormalities, and it can differ­ entiate stomatocytosis from spherocytosis. Enzyme Abnormalities  When an important defect in a compo­ nent of the membrane-cytoskeleton complex is present, hemolysis is a direct consequence of the fact that the very structure of the red cell is compromised. Instead, when one of the enzymes is defective, the consequences will depend on the precise role of that enzyme in the metabolic machinery of the red cell. This machinery has two main functions: (1) to provide energy in the form of ATP, and (2) to prevent oxidative damage to hemoglobin and to other proteins by providing sufficient reductive potential; the key molecule for this is NADPH, required for regeneration of glutathione (GSH) and for degradation of H2O2. ABNORMALITIES OF THE GLYCOLYTIC PATHWAY  Because red cells, in the course of their differentiation, have sacrificed not only their nucleus and their ribosomes but also their mitochondria, they rely exclusively on the anaerobic portion of the glycolytic pathway for producing ATP, most of which is required by the red cell for cation transport against a concentration gradient across the membrane. If this fails due to a defect of any of the enzymes of the glycolytic pathway (Table 105-4), the result will be hemolytic disease. PART 4 Oncology and Hematology Pyruvate Kinase Deficiency  Abnormalities of the glycolytic pathway are all inherited and all rare. Among them, deficiency of pyruvate kinase (PK) is the least rare, with an estimated prevalence in most populations of 1:10,000. However, recently, a polymorphic PK mutation (E277K) was found in some African populations with heterozygote frequen­ cies of 1–7%, suggesting that this may be another malaria-related TABLE 105-4  Red Cell Enzyme Abnormalities Causing Hemolysis GENE SYMBOL; CHROMOSOMAL LOCATION PREVALENCE OF ENZYME DEFICIENCY (RANK) ENZYME (ACRONYM) Glycolytic Pathway Hexokinase (HK) HK1; 10q22 Very rare   May benefit from splenectomy; BMTc Glucose-6-phosphate isomerase (G6PI) GPI; 19q31.1 Rare (4); at least 60 cases reporteda NM, CNS May benefit from splenectomy Phosphofructokinase (PFK)b PFKM; 12q13 Very rare Myopathy; myoglobinuria Aldolase ALDOA; 16q22-24 Very rare Myopathy   Triose phosphate isomerase (TPI) TPI1; 12p13.31 Very rare CNS (severe), NM   Glyceraldehyde 3-phosphate dehydrogenase (GAPD) GAPDH; 12p13.31 Very rare Myopathy   Bisphosphoglycerate mutase (BPGM) BPGM; 7q33 Very rare   Erythrocytosis rather than hemolysis; some of the rare mutations are in the enzyme active site Phosphoglycerate kinase (PGK) PGK1; Xq21.1 Very rare CNS, NM May benefit from splenectomy; BMTc Pyruvate kinase (PK) PKLR; 1q22 Rare (2)a   May benefit from splenectomy; BMTc Redox Glucose-6-phosphate dehydrogenase (G6PD) G6PD; Xq28 Common (1)a Very rarely granulocytes In almost all cases, only AHA from Glutathione synthase GSS; 20q11.22 Very rare CNS   Glutathione reductase GSR; 8p12 Very rare Cataracts AHA from exogenous trigger (favism) γ-Glutamylcysteine synthase GCLC; 6p12.1 Very rare CNS Mutations affect catalytic subunit Cytochrome b5 reductase CYB5R3; 22q13.2 Rare CNS Methemoglobinemia rather than hemolysis Nucleotide Metabolism Adenylate kinase (AK) AK1; 9q34.11 Very rare CNS May benefit from splenectomy Pyrimidine 5’ nucleotidase (P5N) NTSC3A; 7p14.3 Rare (3)a   May benefit from splenectomy aThe numbers from (1) to (4) indicate the ranking order of these enzymopathies in terms of frequency. bPFK deficiency is associated with increased glycogen in muscle, and it is also known as glycogen storage disease type VII or Tarui’s disease. cOccasional report of successful treatment of the hematologic manifestations by BMT. Abbreviations: AHA, acquired hemolytic anemia; BMT, bone marrow transplantation; CNS, central nervous system; NM, neuromuscular. polymorphism. HA secondary to PK deficiency is an autosomal reces­ sive disease (Fig. 105-5). The clinical picture of homozygous (or biallelic) PK deficiency is that of an HA that often presents in the newborn with severe neo­ natal jaundice, requiring nearly always phototherapy and frequently exchange transfusion; the jaundice often persists, and it is often associated with reticulocytosis. The anemia is of variable severity; sometimes it is so severe as to require regular blood transfusion treat­ ment, whereas sometimes it is mild, bordering on a nearly compen­ sated hemolytic disorder. As a result, the diagnosis may be delayed: in some cases, it is made, for instance, in a young woman during her first pregnancy, when the anemia may get worse. The delay in diagnosis may be caused in part by the fact that the anemia is often remarkably well tolerated because the metabolic block at the last step in glycolysis causes an increase in 2,3-bisphosphoglycerate (or DPG; Fig. 105-1), a major effector of the hemoglobin-oxygen dissociation curve; thus, for a certain level of hemoglobin, the oxygen delivery to the tissues is enhanced, a remarkable compensatory feat. TREATMENT Pyruvate Kinase Deficiency Until recently, the management of PK deficiency has been sup­ portive. Folic acid supplements should be given constantly. Blood transfusion should be used as necessary, and iron chelation may be required even in some patients who, though not receiving blood transfusion, may be developing iron overload (see “General Pathophysiology” above). About one-half of patients sooner or later undergo splenectomy, which usually provides a modest but significant increase in hemoglobin (paradoxically, reticulocytes also often increase, because they were previously trapped in the CLINICAL MANIFESTATIONS EXTRA-RED CELL COMMENTS   exogenous trigger PK deficiency G6PD deficiency (autosomal) (X-linked) Homozygous normal Heterozygous Homozygous deficient FIGURE 105-5  Different phenotypes of heterozygotes for red cell enzymopathies. In a heterozygote for deficiency of pyruvate kinase (PK), encoded by an autosomal gene (see Table 105-4), the level of enzyme is about one-half of normal in all red cells. Because this level of enzyme is sufficient, there are no clinical consequences, i.e., PK deficiency is recessive. In a heterozygote for deficiency of glucose-6-phosphate dehydrogenase (G6PD), encoded by an X-linked gene, the situation is quite different: X-chromosome inactivation generates red cell mosaicism, whereby some red cells are entirely normal and others are G6PD deficient. Therefore, G6PD deficiency is expressed in heterozygotes; it is not recessive. spleen). Cholecystectomy may also be required. A major advance has been the introduction of mitapivat, an allosteric activator of PK, and the first drug for a red cell enzymopathy, approved on grounds of a significant increase in hemoglobin in one-half of PK-deficient patients—those in whom either one or both PKLR mutations are of the missense type. Some patients with severe disease have received bone marrow transplantation (BMT) from human leukocyte anti­ gen (HLA)-identical PK-normal sibling. Prenatal diagnosis has been carried out in a mother who had already had an affected child. Rescue of inherited PK deficiency through lentiviral-mediated human PK gene transfer has been successful in mice and is cur­ rently undergoing a clinical trial in patients. Other Glycolytic Enzyme Abnormalities  All of these defects are rare to very rare (Table 105-4), and most of them cause HA with varying degrees of severity. It is not unusual for the presentation to be in the guise of severe neonatal jaundice, which may require exchange transfusion; if the anemia is less severe, it may present later in life, or it may even remain asymptomatic and be detected incidentally when a blood count is done for unrelated reasons. The spleen is often enlarged. When other systemic manifestations occur, they can involve the central nervous system (sometimes entailing severe intellectual disability, particularly in the case of triose phosphate isomerase deficiency), the neuromuscu­ lar system, or both (see Table 105-4). This is not altogether surprising if we consider that these are housekeeping genes, i.e., expressed in all tissues. The diagnosis of HA is usually not difficult, thanks to the triad of normo-macrocytic anemia, reticulocytosis, and hyperbilirubinemia. Enzymopathies should be considered in the differential diagnosis of any chronic Coombs-negative HA. Unlike with membrane disorders, in most cases of glycolytic enzymopathies, morphologic abnormali­ ties are conspicuous by their absence. A definitive diagnosis can be made only by demonstrating the deficiency of an individual enzyme by quantitative assays; these are carried out in only a few specialized laboratories. If a particular molecular abnormality is already known in the family, then one could test directly for that defect at the DNA level, thus bypassing the need for enzyme assays. Of course, the time may be getting nearer when a patient will present with their exome already sequenced, and we will need to concentrate on which genes to look up within the file. The principles for the management of these conditions are similar as for PK deficiency. In isolated clinically severe cases of glycolytic enzyme abnormalities, BMT has been carried out success­ fully, although unfortunately, nonhematologic manifestations, if any, are not reversed. ABNORMALITIES OF REDOX METABOLISM  •  Glucose-6-Phosphate Dehydrogenase (G6PD) Deficiency  G6PD is a housekeeping enzyme critical in the redox metabolism of all aerobic cells (Fig. 105-1). In red cells, its role is even more critical because it is the only source of NADPH, which directly and via GSH defends these cells against oxidative stress (Fig. 105-6). G6PD deficiency–related HA is a prime example of an HA due to interaction between an intracorpuscular cause and an extracorpuscular cause; indeed, in the vast majority of cases, hemolysis is triggered by an exogenous agent. Although the G6PD activity is decreased in most tissues of G6PD-deficient subjects, in other cells, the decrease is much less pronounced than in red cells, and it does not seem to impact on clinical expression. ■ ■GENETIC CONSIDERATIONS The G6PD gene is X-linked, and this has important implications. First, because males have only one G6PD gene (i.e., they are hemizygous for this gene), they must be either normal or G6PD deficient. By contrast, females, who have two G6PD genes, can be either normal or deficient (homozygous) or intermediate (heterozy­ gous). Second, as a result of the phenomenon of X chromosome inac­ tivation, heterozygous females are genetic mosaics (see Fig. 105-5), with a highly variable ratio of G6PD-normal to G6PD-deficient cells and an equally variable degree of clinical expression; some heterozy­ gotes can be just as affected as hemizygous males. The enzymatically active form of G6PD is either a dimer or a tetramer of a single protein subunit of 514 amino acids. G6PD-deficient subjects have been found invariably to have mutations in the coding region of the G6PD gene. Almost all of the over 230 different mutations known are single mis­ sense point mutations, entailing single amino acid replacements in the G6PD protein. In most cases, these mutations cause G6PD deficiency by decreasing the in vivo stability of the protein; thus, the physiologic decrease in G6PD activity that takes place with red cell aging is greatly accelerated. In some cases, an amino acid replacement can also affect the catalytic function of the enzyme. The genetic heterogeneity of G6PD deficiency is clinically important, and for the variants that are widespread, it also has public health implications. Therefore, the World Health Organization (WHO) has worked out a classification (Table 105-5). CHAPTER 105 Hemolytic Anemias Among these mutations, those underlying chronic nonspherocytic hemolytic anemia (CNSHA; see below) are a discrete subset. This much more severe clinical phenotype can be ascribed in some cases to adverse qualitative changes (e.g., a decreased affinity for the substrate glucose-6-phosphate) or simply to the fact that the enzyme deficit is more extreme because of a more severe instability of the enzyme. For instance, a cluster of mutations map at or near the dimer interface, and clearly, they compromise severely the formation of the dimer. Epidemiology  G6PD deficiency is widely distributed in tropical and subtropical parts of the world (Africa, southern Europe, the Middle East, Southeast Asia, and Oceania) (Fig. 105-7) and wherever people from those areas have migrated. A conservative estimate is that at least 500 million people have a G6PD deficiency gene. In several of these areas, the frequency of a G6PD deficiency gene may be as high as 20% or more. It would be quite extraordinary for a trait that causes significant pathology to spread widely and reach high frequencies in many populations without conferring some biologic advantage. Indeed, G6PD is one of the best-characterized examples of genetic polymorphisms in the human species. Clinical field studies and in vitro experiments strongly support the view that G6PD deficiency has been selected by Plasmodium falciparum malaria because it confers a relative resistance against this highly lethal infection. As in other cases of balanced polymorphism, it is heterozygotes, therefore females, who are protected. Different G6PD variants (class B) underlie most of the prevalence of G6PD deficiency in different parts of the world. Exam­ ples of widespread variants are G6PD Mediterranean on the shores of that sea, in the Middle East, and elsewhere; G6PD A– in Africa, in the Middle East, and in southern Europe; G6PD Orissa in India; G6PD Viangchan and G6PD Mahidol in Southeast Asia; G6PD Kaiping and G6PD Canton in China; and G6PD Union worldwide. The heterogene­ ity of polymorphic G6PD variants is proof of their independent origin, further supporting the notion of selection by a common environmental Divicine (fava beans) Primaquine ROS from neutrophils O2 – Superoxide dismutase Rasburicase H2O2 Uric acid GSH Catalase Glutathione reductase Prx2-SHGSSG NADPH H2O Glutathione peroxidase Prx2-S-SA Divicine (fava beans) Primaquine OXIDATIVE DAMAGE ROS from neutrophils O2 – PART 4 Oncology and Hematology Superoxide dismutase Rasburicase H2O2 Uric acid GSH Catalase Glutathione reductase Prx2-SHGSSG NADPH H2O Glutathione peroxidase Prx2-S-SB FIGURE 105-6  The role of glucose-6-phosphate dehydrogenase (G6PD) in protecting red cells from oxidative damage. A. In G6PD-normal red cells, G6PD and 6-phosphogluconate dehydrogenase—two of the enzymes of the pentose phosphate pathway—provide ample supply of NADPH, which in turn regenerates glutathione (GSH) when this is oxidized by reactive oxygen species (e.g., O2 – and H2O2). Thus when O2 – (meant here to represent itself and other reactive oxygen species [ROS]) is produced by pro-oxidant compounds such as primaquine, or the glucosides in fava beans (divicine), or the oxidative burst of neutrophils, these ROS are rapidly neutralized; similarly, when rasburicase administered to degrade uric acid produces an equimolar amount of hydrogen peroxide, this is rapidly degraded by the combined action of glutathione peroxidase, catalase, and Prx2 (peroxiredoxin-2; all three mechanisms are NADPH dependent). B. In G6PD-deficient red cells, where the enzyme activity is reduced, NADPH production is limited, and it may not be sufficient to cope with the excess ROS generated by pro-oxidant compounds and the consequent excess hydrogen peroxide. This diagram also explains why a defect in GSH reductase has very similar consequences to G6PD deficiency. agent, namely malaria, in keeping with the concept of convergent evo­ lution (Fig. 105-7). Clinical Manifestations  The vast majority of people with G6PD defi­ ciency remain clinically asymptomatic throughout their lifetime; how­ ever, all of them have an increased risk of developing neonatal jaundice (NNJ) and a risk of developing acute HA (AHA) when challenged by a number of oxidative agents. NNJ related to G6PD deficiency is rarely present at birth; the peak incidence of clinical onset is between day 2 and day 3, and in most cases, the anemia is not severe. However, TABLE 105-5  Current World Health Organization Classification of Glucose 6-Phosphate Dehydrogenase (G6PD) Variants G6PD VARIANT CLASS MEDIAN OF G6PD ACTIVITY (% OF NORMAL) ASSOCIATED CLINICAL MANIFESTATIONS Aa <20%b Chronic hemolytic anemia Bc <45% Neonatal jaundice; acute hemolytic anemia triggered by certain medicines, fava beans, and infections Ca >60% None reported Ud Any Uncertain clinical significance aClass A corresponds to former class I; class C corresponds to former class IV. bA variant with <20% activity will be in class A only if it is associated with chronic hemolytic anemia. cIn view of the extensive overlap in enzyme activity and in clinical expression of variants in former class II and class III, these have been merged into class B. dA temporary assignment for variants for which there is currently insufficient information regarding clinical manifestations. Glucose 6-phosphate NADP Glucose 6-phosphate dehydrogenase 6-Phosphoglucono-δ-lactone 6-Phosphoglucono lactonase 6-Phosphogluconate 6-Phosphogluconate dehydrogenase Ribulose 5-phosphate Glucose 6-phosphate NADP Glucose 6-phosphate dehydrogenase 6-Phosphoglucono-δ-lactone 6-Phosphoglucono lactonase 6-Phosphogluconate 6-Phosphogluconate dehydrogenase Ribulose 5-phosphate NNJ can be very severe in some G6PD-deficient babies, especially in association with prematurity, infection, and/or environmental factors (e.g., naphthalene-camphor balls, which may be used in babies’ bed­ ding and clothing); and the risk of severe NNJ is also increased by the coexistence of a monoallelic or biallelic mutation in the uridyl trans­ ferase gene (UGT1A1; the same mutations are associated with Gilbert’s syndrome). It is imperative to manage promptly NNJ associated with G6PD deficiency because it can produce kernicterus and permanent neurologic damage. AHA can develop as a result of three types of triggers: (1) fava beans, (2) infections, and (3) drugs (Table 105-6). Typically, a hemolytic attack starts with malaise, weakness, and abdominal or lumbar pain. Within a time frame of several hours to 2–3 days, the patient develops jaundice and often dark urine. The onset can be extremely abrupt, especially with favism in children. The anemia is moderate to extremely severe, usually normocytic and normochromic, and due partly to intravascular hemolysis; hence, it is associated with hemoglobinemia, hemoglobin­ uria, high LDH, and low or absent plasma haptoglobin. The blood film shows anisocytosis, polychromasia, and spherocytes; in addition, the most typical feature of G6PD deficiency is the presence of bizarre poikilocytes, with red cells that appear to have unevenly distributed hemoglobin (“hemighosts”) and red cells that appear to have had parts of them bitten away (“bite cells” or “blister cells”) (Fig. 105-8). A classi­ cal test, now rarely carried out, is supravital staining with methyl violet, which, if done promptly, reveals the presence of Heinz bodies (consist­ ing of precipitates of denatured hemoglobin and hemichromes), which are regarded as a signature of oxidative damage to red cells (they are A– Canton Coimbra Kaiping Kalyan Mahidol Med Orissa Union Viangchan No data <1% 1–4.9% 5–9.9% 10–14.9% 15–19.9% >20% FIGURE 105-7  Epidemiology of glucose-6-phosphate dehydrogenase (G6PD) deficiency throughout the world. Each country on the map is shaded in a color based on the best estimate of the mean frequency of G6PD deficiency allele(s) in that country (this is the same as the frequency of G6PD-deficient males). The small panel on the left gives the key to color shadings corresponding to each country. The larger panel gives a color-coded list of 10 common G6PD variants associated with G6PD deficiency: asteriskshaped symbols in the corresponding colors are shown in the countries where these variants have been observed (for graphic reasons, symbols could not be inserted in all countries). (Reproduced with permission from L Luzzatto, M Ally, R Notaro. Glucose-6-phosphate dehydrogenase deficiency. 136:1225, 2020.) also seen with unstable hemoglobins). Since there is also a substantial component of extravascular hemolysis, unconjugated bilirubin is high and there is often clinical icterus. The most serious threat from AHA in adults is the development of acute renal failure (this is exceedingly rare in children). Once the threat of acute anemia is over and in the TABLE 105-6  Drugs That Carry Risk of Clinical Hemolysis in Persons with Glucose 6-Phosphate Dehydrogenase Deficiency RISK OF ACUTE HEMOLYTIC ANEMIA DRUG CLASS HIGH MEDIUM TO LOW   Antimalarials Primaquine Tafenoquine Chloroquine Hydroxychloroquine Quinine   Sulphonamides/ sulphones Dapsone Sulfadimidine Sulfamethoxazole Sulfasalazine   Antibacterial/ antibiotics   Chloramphenicol Ciprofloxacin Cotrimoxazole Nalidixic acid Nitrofurantoin Norfloxacin p-Aminosalicylic acid   Anti-helmint   Niridazole   Antipyretic/ analgesics Acetylsalicylic acid high dose (>3 g/d) Acetaminophen Acetanilide Phenacetin Phenazopyridine   Other Rasburicase Pegloticase Methylene blue Toluidine blue Ascorbic acid (>1 g) Doxorubicin Probenecid Vitamin K analogues   CHAPTER 105 Hemolytic Anemias absence of comorbidity, full recovery from AHA associated with G6PD deficiency is the rule. It was primaquine (PQ)-induced AHA that led to the discovery of G6PD deficiency, but this drug has not been very prominent subse­ quently because it is not necessary for the treatment of life-threatening P. falciparum malaria. Today there is a revival in the use of PQ for two reasons. First, it is the only effective agent for eliminating the gameto­ cytes of P. falciparum (thus preventing further transmission): a small single dose (0.25 mg/kg) is required, and it is safe for G6PD-deficient persons. Second, a 14-day course of PQ is the standard treatment for eliminating the hypnozoites of Plasmodium vivax (thus preventing endogenous relapse) (Chap. 231). In countries aiming to eliminate malaria, there may be a call for mass administration of PQ; this ought FIGURE 105-8  Peripheral blood smear from a glucose-6-phosphate dehydrogenase (G6PD)-deficient boy experiencing hemolysis. Note the red cells that are misshapen and called “bite” cells. (From MA Lichtman et al: Lichtman’s Atlas of Hematology: http://www.accessmedicine.com. Copyright © The McGraw-Hill Companies, Inc. All rights reserved.) to be associated with G6PD testing. At the other end of the historic spectrum, the latest additions to the list of potentially hemolytic drugs (Table 105-6) are rasburicase and pegloticase; again, G6PD test­ ing ought to be made mandatory before giving either of these drugs because fatal cases have been reported upon using one of these drugs, which generate hydrogen peroxide, in newborns with kidney injury and in children and adults with tumor lysis syndrome. Although drug-induced AHA has been prominent in the study of G6PD deficiency, the most common clinical manifestations are in fact NNJ and favism, both of which are of public health importance in many populations. Contrary to beliefs that are still widespread, fava bean pollen inhalation does not cause favism, and other beans are safe. A very small minority of subjects with G6PD deficiency, those who have a class A variant, suffer from CNSHA of variable severity. The patient is nearly always a male, usually with a history of NNJ, who may present with anemia, unexplained jaundice, or gallstones later in life. The spleen may be enlarged. The severity of anemia ranges in differ­ ent patients from borderline to transfusion dependent. The anemia is usually normo-macrocytic, with reticulocytosis. Bilirubin and LDH are increased. Although hemolysis is, by definition, chronic in these patients, they are also vulnerable to acute oxidative damage, and there­ fore, the same agents that can cause AHA in people with the ordinary type of G6PD deficiency will cause severe exacerbations in people with CNSHA associated with G6PD deficiency. In some cases of CNSHA, the deficiency of G6PD is so severe in granulocytes that it limits their capacity to produce an oxidative burst, with consequent increased sus­ ceptibility to some bacterial infections. PART 4 Oncology and Hematology Laboratory Diagnosis  The suspicion of G6PD deficiency can be con­ firmed by semiquantitative methods often referred to as screening tests, which are suitable for population studies and can correctly clas­ sify male subjects, in the steady state, as G6PD normal or G6PD defi­ cient. However, in clinical practice, a diagnostic test is usually needed when the patient has had a hemolytic attack, whereby the oldest, most G6PD-deficient red cells have been selectively destroyed, and young red cells, having higher G6PD activity, are being released into the circulation. Under these conditions, only a quantitative test can give a definitive result. In males, this test will identify normal hemizygotes and G6PD-deficient hemizygotes; among females, some heterozygotes will be missed, but those who are at most risk of hemolysis will be iden­ tified. Of course, G6PD deficiency also can be diagnosed by DNA test­ ing. Currently easy-to-use point-of-care tests for G6PD deficiency are becoming available, geared especially to the prospect of mass adminis­ tration of PQ or of the newly introduced derivative tafenoquine. TREATMENT G6PD Deficiency The AHA of G6PD deficiency is largely preventable by avoiding exposure to triggering factors of previously screened subjects. Of course, the practicability and cost-effectiveness of screening depend on the prevalence of G6PD deficiency in each individual commu­ nity. Favism is entirely preventable in G6PD-deficient subjects by not eating fava beans. Drug-induced hemolysis can be prevented by testing for G6PD deficiency before prescribing; in many cases, one can use alternative drugs. When AHA develops and once its cause is recognized, no specific treatment is needed in most cases. However, if the anemia is severe, it may be a medical emergency, especially in children, requiring immediate action, including blood transfu­ sion. This has been the case with an antimalarial drug combination containing dapsone (called Lapdap, introduced in 2003) that has caused severe acute hemolytic episodes in children with malaria in several African countries; after a few years, the drug was taken off the market. If there is acute renal failure, hemodialysis may be necessary, but if there is no previous kidney disease, recovery is the rule. The management of NNJ associated with G6PD deficiency is no different from that of NNJ due to other causes. In cases with CNSHA, if the anemia is not severe, regular folic acid supplements and regular hematologic surveillance will suffice. It will be important to avoid exposure to potentially hemolytic drugs, and blood transfusion may be indicated when exacerbations occur, mostly in concomitance with intercurrent infection. In rare patients, regular blood transfusions may be required, in which case appropriate iron chelation should be instituted. Unlike in HS, there is no evidence of selective red cell destruction in the spleen; how­ ever, in practice, splenectomy has proven beneficial in severe cases. Other Abnormalities of the Redox System  As mentioned previously, GSH is a key player in the defense against oxidative stress. Inherited defects of GSH metabolism are exceedingly rare, but each one can give rise to chronic HA (Table 105-4). A rare, peculiar, and severe but usually self-limited HA occurring in the first month of life, called infantile poikilocytosis, may be associated with deficiency of glutathione peroxidase (GSHPX) due not to an inherited abnormality, but to transient nutritional deficiency of selenium, an element essential for the activity of GSHPX. PYRIMIDINE 5′-NUCLEOTIDASE (P5N) DEFICIENCY  P5N is a key enzyme in the catabolism of nucleotides arising from the degradation of nucleic acids that takes place in the final stages of erythroid cell matura­ tion. How exactly its deficiency causes HA is not well understood, but a highly distinctive feature of this condition is a morphologic abnormal­ ity of the red cells known as basophilic stippling. The condition is rare, but it probably ranks third in frequency among red cell enzyme defects (after G6PD deficiency and PK deficiency). The anemia is lifelong, is of variable severity, and may benefit from splenectomy. Familial (Atypical) Hemolytic-Uremic Syndrome (aHUS)  This term is used to designate a group of rare disorders, mostly affect­ ing children, characterized by microangiopathic HA with presence of fragmented erythrocytes in the peripheral blood smear, thrombocy­ topenia (usually mild), and acute renal failure. (The word atypical in this phrase should be consigned to history; it was introduced originally to distinguish this condition from the hemolytic-uremic syndrome [HUS] caused by infection with Escherichia coli producing the Shiga toxin, regarded as typical.) The disease is caused by dysregulation of the complement alternative pathway: in some cases, this results from anti–factor H autoantibodies, but in the majority of cases, it is a conse­ quence of mutations in genes encoding proteins that are components or regulators of the complement system, i.e., C3 (encoding complement component C3), CFB (encoding complement factor B), CFH (encod­ ing complement factor H), CD46 (encoding the membrane cofactor protein), CFI (encoding complement factor I), THBD (encoding thrombomodulin), and rarely others. Patients may have abnormalities in one, two, or even three of the above genes. Pathogenic variants of these genes predispose to HUS with autosomal dominant inheritance; because clinical aHUS requires a triggering factor, most commonly infection, the penetrance is incomplete. Thus, whereas all other inher­ ited HAs are due to intrinsic red cell abnormalities, this group is unique in that hemolysis results from an inherited defect external to red cells (Table 105-1). Because the regulation of the complement cascade has considerable redundancy, in the steady state, any of the above abnor­ malities can be tolerated. However, when an intercurrent infection or some other trigger briskly activates complement, the deficiency of one of the complement regulators becomes critical. Endothelial cells get damaged, especially in the kidney. At the same time, and partly as a result of this, there will be brisk hemolysis; thus, the more common Shiga toxin–related HUS (Chap. 172) can be regarded as a phenocopy of aHUS. aHUS is a severe disease; before anticomplement therapy was available, mortality was up to 15% in the acute phase, and up to 50% of cases progressed to end-stage renal disease (ESRD). Not infrequently, aHUS undergoes spontaneous remission. Because it is an inherited abnormality, it is not surprising that, given renewed exposure to a trigger, the syndrome will tend to recur; when it does, the prognosis is always serious. The traditional treatment has been plasma exchange, which will supply the deficient complement regulator and clear complement activation products. This has changed since the introduc­ tion of the anti-C5 complement inhibitor eculizumab (see “Paroxysmal Nocturnal Hemoglobinuria”), which was found to greatly ameliorate the microangiopathic picture, with improvement in platelet counts and in renal function, thus abrogating the need for plasma exchange, which is not always effective and not free of complications. Once a full remis­ sion is obtained, with urine dipstick negative for hemoglobinuria, within 3–6 months, eculizumab can be discontinued. Given the genetic background of aHUS, relapses are possible. Fortunately, patients who relapsed after discontinuing eculizumab have responded again. No current evidence supports continuing eculizumab indefinitely. For the diagnosis of inherited red cell abnormalities, including those of the membrane-cytoskeleton, channelopathies, and enzymopathies, DNA sequencing of a gene panel (e.g., next-generation sequencing [NGS]) has become increasingly popular. This approach (which may or may not be more expensive) has the advantage of being potentially comprehensive and of providing definitive data. On the other hand, the mutations identified may be of uncertain significance, in which case, the diagnosis must be still confirmed by conventional methodology. Thus, the use of NGS is specially useful with unsolved cases of hereditary HAs. ■ ■ACQUIRED HEMOLYTIC ANEMIA Mechanical Destruction of Red Cells  Although red cells are characterized by the remarkable deformability that enables them to squeeze through capillaries narrower than themselves for thousands of times in their lifetime, there are at least two situations in which they succumb to shear, if not to wear and tear; the result is intravascular hemolysis, resulting in hemoglobinuria (Table 105-7). One situation is acute and self-inflicted, march hemoglobinuria. Why sometimes a marathon runner may develop this complication, whereas on another occasion, this does not happen, we do not know (perhaps their footwear needs attention). A similar syndrome may develop after prolonged barefoot ritual dancing or intense playing of bongo drums. The other situation is chronic and iatrogenic (it has been called micro­ angiopathic hemolytic anemia). It takes place in patients with prosthetic heart valves, especially when paraprosthetic regurgitation is present. If the hemolysis consequent on mechanical trauma to the red cells is mild, and if the supply of iron is adequate, the loss may be largely com­ pensated; if more than mild anemia develops, reintervention to correct regurgitation may be required. Infection  By far, the most frequent infectious cause of HA in endemic areas is malaria (Chap. 231). In other parts of the world, the most frequent direct cause is probably Shiga toxin–producing E. coli O157:H7, now recognized as the main etiologic agent of HUS, which is more common in children than in adults (Chap. 166). Life-threatening intravascular hemolysis, due to a toxin with lecithinase activity, occurs with Clostridium perfringens sepsis, particularly following open wounds, septic abortion, or as a disastrous accident due to a contami­ nated blood unit. Rarely, and if at all in children, HA is seen with sepsis or endocarditis from a variety of organisms. In addition, bacterial and viral infections can cause HA by indirect mechanisms (see Table 105-7). TABLE 105-7  Diseases and Clinical Situations in Which Hemolysis Is Largely Intravascular   ONSET/TIME COURSE MAIN MECHANISM Mismatched blood transfusion Abrupt Nearly always ABO incompatibility Paroxysmal nocturnal hemoglobinuria (PNH) Chronic with acute exacerbations Complement (C)-mediated destruction of CD59(−) red cells Paroxysmal cold hemoglobinuria (PCH) Acute Immune lysis of normal red cells Septicemia Very acute Exotoxins produced by Clostridium perfringens Microangiopathic Acute or chronic Red cell fragmentation Red cell morphology on blood smear March hemoglobinuria Abrupt Mechanical destruction Targeted history taking Has been reported after extreme ritual dancing Favism Acute Destruction of older fraction of G6PD-deficient red cells aThe trigger of acute hemolytic anemia, often with hemoglobinuria, can be infection or a drug (see Table 105-5) rather than fava beans. Hemoglobinuria may or may not be reported by patient, but it is often macroscopic, i.e., recognizable by simple inspection of urine. Abbreviation: G6PD, glucose 6-phosphate dehydrogenase. Immune Hemolytic Anemias  These can arise through at least two distinct mechanisms. First, when an antibody directed against a certain molecule (e.g., a drug) reacts with that molecule, red cells may get caught in the reaction (the so-called innocent bystander mechanism; see later section “Hemolytic Anemia from Toxic Agents and Drugs”), whereby they are damaged or destroyed. Second, and more frequently, a true autoantibody is directed against a red cell antigen, i.e., a molecule present on the surface of red cells. Autoimmune HAs have been origi­ nally classified into two types, depending on the thermal amplitude of the autoantibodies involved; this classification is valid because the two types have different pathophysiologic and clinical features. AUTOIMMUNE HEMOLYTIC ANEMIA, WARM TYPE (WAIHA; FOR SIM­ PLICITY, WE WILL USE THE ACRONYM AIHA)  AIHA has an estimated incidence in the United States of about 1–3:100,000 per year, and a prevalence of 17:100,000. AIHA can be serious because even with appropriate management the mortality is ~5–10%. Clinical Features and Diagnosis  The onset is often abrupt and can be dra­ matic. The hemoglobin level may drop, within days, to as low as 4 g/dL; the massive red cell removal will produce jaundice, and sometimes the spleen is enlarged. When this triad is present, the suspicion of AIHA must be high. The reticulocyte count is typically elevated, except when erythroid precursors are also targeted by the autoantibody attack. LDH may also be elevated. In some cases, AIHA can be associated, on first presentation or subsequently, with autoimmune thrombocytopenia. This double autoim­ mune condition, referred to as Evans syndrome, may be a manifestation of common variable immune deficiency, and in children, it may suggest one of several primary immune deficiency syndromes. Evans syndrome signals high-risk disease. Other predictors of the outcome and of the prob­ ability of relapse of AIHA are severe anemia (hemoglobin <6 g/dL), certain characteristics of the antibody, acute renal failure, and infection. CHAPTER 105 Hemolytic Anemias There are few situations in hematology where one laboratory test is as informative as the direct antiglobulin test developed in 1945 by R. R. A. Coombs and known since then by this name. The currently recommended version of this test uses in the first instance a “broadspectrum” reagent, i.e., one that will detect not only immunoglobulins (Ig) but also complement (C) components (usually C3 fragments) bound to the surface of the patient’s red cells. If the test is positive, it is, almost on its own, diagnostic of AIHA. False positives may occur as a result of previous blood transfusion or, much more rarely, fol­ lowing organ transplantation procedures or administration of antilymphocyte or immunoglobulin products. One can then determine, by using specific reagents, whether Ig or C or both are implicated. The sensitivity of the Coombs test varies depending on the techniques that are used. In general, the test is positive if there is an average of at least 400 molecules of Ig and/or C on each red cell; but with more advanced techniques involving flow cytometry analysis or enzyme-linked radio­ labeled tests, the sensitivity can be pushed to as low as 30–40 molecules APPROPRIATE DIAGNOSTIC PROCEDURE COMMENTS Repeat cross-match   Flow cytometry to display a CD59(−) red cell population Exacerbations due to C activation through any pathway Test for Donath-Landsteiner antibody Often triggered by viral infection Blood cultures Other organisms may be responsible Different causes ranging from endothelial damage to hemangioma to leaky prosthetic heart valve G6PD assay Triggered by ingestion of large dish of fava beansa per red cell. Therefore, liaison with a specialized laboratory is desirable; a dual direct antiglobulin test has also been developed. In the past, the diagnosis of “Coombs-negative AIHA” was regarded as a last resort, but it is important to know that a patient with this label may have severe AIHA, because if the antibody is powerful (high affinity/avidity), few molecules may be sufficient to opsonize red cells. Based on the Coombs test findings as well as on the thermal characteristics and the antigenic specificities of the autoantibodies (Table 105-8), AIHA has been classified into subtypes. In AIHA, the autoantibody reacts best at 37°C, and it is usually Rhesus specific (sometimes specifically anti-e). The main mechanism of hemolysis in AIHA is that the Fc portion of the IgG antibody bound to red cells is recognized by the Fc receptor of macrophages. This will trigger erythrophagocytosis wherever macrophages are abundant, i.e., in the liver, in the bone marrow, but especially in red pulp of the spleen (Fig. 105-9), which, also because of its special anatomy, is often the predominant site of red cell destruction. AIHA may be seen in isolation (and it is then called idiopathic) or as secondary to other disorders such as systemic autoimmune disorders (systemic lupus erythematosus [SLE]; sometimes, AIHA may be the first manifestation that leads to a diagnosis of SLE) or lymphoprolif­ erative disorders (Table 105-8). Like all autoimmune diseases, AIHA must arise from a dysregulation of immunity. It is therefore not sur­ prising that it is increasingly being recognized in chronic lymphocytic PART 4 Oncology and Hematology TABLE 105-8  Classification of Acquired Immune Hemolytic Anemias TYPE OF ANTIBODY COLD, MOSTLY IgM, OPTIMAL TEMPERATURE 4°C–30°C WARM, MOSTLY IgG, OPTIMAL TEMPERATURE 37°C; OR MIXED CLINICAL SETTING Primary CAD AIHA (idiopathic) Secondary to viral infection EBV CMV Other Parvovirus B19 HIV HCV EBV Viral vaccines Secondary to other infection Mycoplasma infection: paroxysmal cold hemoglobinuria Babesia Secondary to/ associated with other disease CAD in: Waldenström’s disease Lymphoma AIHA in: SLE, scleroderma, RA CLL Lymphoproliferative disorders Multiple myeloma Other malignancy Chronic inflammatory disorders (e.g., IBD) Thyroiditis (including Hashimoto) After allogeneic HSCT Common variable immunodeficiency After immune checkpoint modulating drugs Secondary to drugs: druginduced immune hemolytic anemia Small minority (e.g., with lenalidomide) Majority: currently most common culprit drugs are cefotetan, ceftriaxone, piperacillin, methyldopa, fludarabine Drug-dependent: antibody destroys red cells only when drug present (e.g., rarely penicillin) Drug-independent: antibody can destroy red cells even when drug no longer present (e.g., methyldopa) Associated with Pregnancy Abbreviations: AIHA, autoimmune hemolytic anemia; CAD, cold agglutinin disease; CLL, chronic lymphocytic leukemia; CMV, cytomegalovirus; EBV, Epstein-Barr virus; HCV, hepatitis C virus; HIV, human immunodeficiency virus; HSCT, hematopoietic stem cell transplantation; IBD, inflammatory bowel disease; SLE, systemic lupus erythematosus; RA, rheumatoid arthritis. leukemia (CLL), whether treated or untreated; after BMT; and after solid organ transplantation entailing immunosuppressive treatment. Recently, warm antibody AIHA has also occurred as a side effect of the use of immune checkpoint inhibitors, such as nivolumab, in patients with various types of cancer. TREATMENT Warm Antibody Autoimmune Hemolytic Anemia Severe acute AIHA can be a medical emergency. The immediate treatment almost invariably includes transfusion of red cells. This may pose a special problem because many or all of the blood units cross-matched may be incompatible. In these cases, it is often cor­ rect, if paradoxical, to transfuse ABO-matched but incompatible blood, with the rationale being that the transfused red cells will be destroyed no less—but no more—than the patient’s own red cells, and in the meantime, the patient stays alive. A situation like this requires close liaison and understanding between the clinical unit treating the patient and the blood transfusion/serology lab. When­ ever the anemia is not immediately life-threatening, blood trans­ fusion should be withheld (because compatibility problems may increase with each unit of blood transfused) and medical treatment started immediately with prednisone (1 mg/kg per day), which will produce a remission promptly in at least one-half of patients. Rituximab (anti-CD20), previously regarded as second-line treat­ ment, is increasingly being used at a relatively low dose (100 mg/ week × 4), together with prednisone as part of first-line treatment. It is especially encouraging that this approach seems to reduce the rate of relapse, a common occurrence in AIHA. For patients who do relapse or are refractory to medical treat­ ment, additional therapeutic strategies are now available. Sple­ nectomy does not cure the disease, but it can produce significant benefit by removing a major site of hemolysis, thus improving the anemia and/or reducing the need for other therapies (e.g., the dose of prednisone); of course, splenectomy is not free of risk, as it entails increased risk of sepsis and of thrombosis. The response rates to splenectomy and rituximab are similar. Since the introduction of rituximab, azathioprine, cyclophosphamide, cyclosporine, myco­ phenolate, and intravenous immunoglobulin have become sec­ ond- or third-line agents. In very rare severe refractory cases, one may have to consider a high dose of cyclophosphamide (50 mg/kg per day for 4 days), followed by a myelo-stimulating agent, or the anti-CD52 agent alemtuzumab. Fostamatinib, an inhibitor of intra­ cellular cell signaling (Syk kinase) mediating erythrophagocytosis, has shown beneficial effects in an open-label clinical study, becom­ ing an interesting third-line therapeutic option (Fig. 105-9). When severe anemia is associated with inadequate reticulocyte output, the use of EPO may help to reduce or avoid the requirement for trans­ fusion of red cells. Several new agents, including inhibitors of the neonatal Fc receptor and others, are currently under investigation. PAROXYSMAL COLD HEMOGLOBINURIA (PCH)  PCH is a rare form of AIHA occurring mostly in children, usually triggered by a viral infec­ tion, usually self-limited, and characterized by the so-called DonathLandsteiner antibody. In vitro, this antibody has unique serologic features; it has usually anti-P specificity, and it binds to red cells only at a low temperature (optimally at 4°C), but when the temperature is shifted to 37°C, lysis of red cells takes place in the presence of comple­ ment. Consequently, in vivo, there is intravascular hemolysis, resulting in hemoglobinuria. Clinically the differential diagnosis must include other causes of hemoglobinuria (Table 105-7), but the presence of the Donath-Landsteiner antibody will prove PCH. Active supportive treatment, including blood transfusion, may be needed to control the anemia; subsequently, recovery is the rule. COLD AGGLUTININ DISEASE  This designation indicates the other main type of AIHA, which has quite different features when compared with warm antibody AIHA. First, cold agglutinin disease (CAD) is a IgG Warm Ab Rituximab Alemtuzumab CD20 CD52 Spleen Fc receptor BTK B cell Venetoclax Ibrutinib Complement blockers (C1S) Plasma cell Complement Bortezomib IgM Cold Ab FIGURE 105-9  Basic mechanisms involved in warm antibody– and cold antibody-mediated autoimmune hemolytic anemias. Top. With warm antibodies (usually IgG), opsonized red cells are removed by Fc receptor–bearing macrophages, largely in the spleen (extravascular hemolysis); fragmentation and spherocyte formation also play a role, with the spleen again being the main site. Bottom. In cold agglutinin disease (CAD), the antibody is IgM, which, once bound to red cells, causes complement activation through the classic pathway, with consequent intravascular hemolysis. In addition, C3b-opsonized red cells will undergo erythrophagocytosis by Kupffer cells in the liver, with consequent extravascular hemolysis. The inset on the left illustrates the B cells that make these autoantibodies: polyclonal in the case of warm antibody–mediated autoimmune hemolytic anemia and monoclonal in the case of CAD. The new therapeutic approaches in addition to glucocorticoids for autoimmune hemolytic anemias are shown in red. The inset highlights drugs targeting immune cells involved in generation of antibodies. Ab, antibody; BTK, Bruton’s tyrosine kinase; Syk, spleen tyrosine kinase. chronic and more frequently indolent condition—in contrast to the abrupt onset of warm antibody AIHA. Second, the term cold refers to the fact that the autoantibody involved reacts with red cells poorly or not at all at 37°C, whereas it reacts strongly at lower temperatures. As a result, hemolysis is more prominent the more the body is exposed to the cold. Third, the antibody is produced by a clone of autoreactive B lymphocytes. Sometimes the antibody concentration in the serum is high enough to show up as a spike in plasma protein electrophoresis, thus qualifying CAD as an IgM monoclonal gammopathy; however, it differs from Waldenström macroglobulinemia by not having the characteristic MYD88 mutation (see Chap. 116); instead, a somatic mutation in the KMT2D gene, encoding a lysine histone methylase, is present in the B-cell clone of a majority of CAD patients: this seems to favor proliferation. The antibody produced by the B-cell clone is IgM; usually it has an anti-I specificity (the I antigen is present on the red cells of almost everybody), and it may have a very high titer (1:100,000 or more has been observed). IgM, when bound to red cells, is a power­ ful activator of the complement cascade, with ultimate formation of the membrane attack complex (see Fig. 105-9); this will directly cause destruction of red cells (intravascular hemolysis; indeed, CAD patients may present with hemoglobinuria). In addition, once complement is activated, C3b will bind to red cells that, thus opsonized, will be destroyed by macrophages (extravascular hemolysis); unlike in AIHA, the spleen is not predominant in this process. In mild forms of CAD, avoidance of exposure to cold may be all that is needed to enable the patient to have a reasonably comfortable quality of life; but in more severe forms, the management of CAD is not easy. Plasma exchange will remove antibodies and is, therefore, in theory, a rational approach in severe cases. However, the management of CAD has changed significantly with the advent of the anti-CD20 antibody rituximab; up to 60% of patients respond. If remission is followed by relapse, a new course of rituximab may be again effective, and remis­ sions may be more durable with a combination of rituximab with either Fostamatinib Spherocytes Syk Erythroid microparticles Extravascular hemolysis Liver Extravascular hemolysis Complement activation with formation of membrane attack complex CHAPTER 105 Intravascular hemolysis Hemolytic Anemias fludarabine or bendamustine, in particular in CAD associated with a clinically manifested lymphoproliferative disorder. Therefore, even in the absence of a formal trial, rituximab has become de facto firstline treatment, especially since previously used immunosuppressive/ cytotoxic agents, although they can reduce the antibody titer, have lim­ ited clinical efficacy and, in view of the chronic nature of CAD, their side effects may prove unacceptable. Unlike in AIHA, prednisone and splenectomy are ineffective. In the management of CAD in relapse, the B-cell receptor inhibitors venetoclax and ibrutinib, as well as for the proteasome inhibitor bortezomib, are emerging as effective agents. A different approach targeting complement inhibitors has been also explored by using sutimlimab (anti-C1s); a limitation of this approach is that hemolysis will be curbed only for as long as this agent is admin­ istered (Fig. 105-9). In terms of supportive treatment, blood transfusion may be help­ ful, despite the fact that red cells from the donor, being I positive, will survive no longer than those of the patient. Both the blood bag and the patient’s extremities must be kept warm during transfusion. Hemolytic Anemia from Toxic Agents and Drugs  A number of chemicals with oxidative potential, whether medicinal or not, can cause hemolysis even in people who are not G6PD deficient (for which, see above). Examples are hyperbaric oxygen (or 100% oxygen), nitrates, chlorates, methylene blue, dapsone, cisplatin, and numerous aromatic (cyclic) compounds. Other chemicals may be hemolytic through nonoxidative, largely unknown mechanisms; examples include arsine, stibine, copper, and lead. The HA caused by lead poisoning is charac­ terized by basophilic stippling; it is in fact a phenocopy of that seen in P5N deficiency (see above), suggesting it is mediated at least in part by lead inhibiting this enzyme. In these cases, hemolysis appears to be mediated by a direct chemi­ cal action on red cells. But drugs can cause hemolysis through at least two other mechanisms. (1) A drug can behave as a hapten and induce antibody production; in rare subjects, this happens, for instance, with penicillin. Upon a subsequent exposure, red cells are caught, as inno­ cent bystanders, in the reaction between penicillin and antipenicillin antibodies. Hemolysis will subside as soon as penicillin administra­ tion is stopped. (2) A drug can trigger, perhaps through mimicry, the production of an antibody against a red cell antigen. The best-known example is methyldopa, an antihypertensive agent no longer in use, which in a small fraction of patients stimulated the production of the Rhesus antibody anti-e. In patients who have this antigen, the anti-e is a true autoantibody, which then causes true AIHA (see above). Usually this will gradually subside once methyldopa is discontinued. Severe intravascular hemolysis can be caused by the venom of cer­ tain snakes (cobras and vipers), and HA can also follow spider bites. Paroxysmal Nocturnal Hemoglobinuria (PNH)  PNH is an acquired chronic HA characterized by persistent intravascular hemo­ lysis with occasional or frequent recurrent exacerbations. In addition to (1) hemolysis, there may be (2) pancytopenia and (3) a distinct tendency to venous thrombosis. This triad makes PNH a truly unique clinical condition; however, when not all of these three features are manifest on presentation, the diagnosis is often delayed, although it can always be made by appropriate laboratory investigations (see below). PNH is encountered in all populations throughout the world, but it is a rare disease, with an estimated prevalence of 5–10 per million (it may be somewhat less rare in Southeast Asia and in the Far East). PNH has about the same frequency in men and women. PNH is not inherited, and it has never been reported as a congenital disease, but it can present in small children or as late as in the seventies, although most patients are young adults. PART 4 Oncology and Hematology CLINICAL FEATURES  When seeking medical attention, the patient may report that one morning, they “passed blood instead of urine.” This distressing or frightening event may be regarded as the classic presentation; however, more frequently, this symptom is not noticed or not reported. Indeed, the patient often presents simply as a prob­ lem in the differential diagnosis of anemia, whether symptomatic or discovered incidentally. Sometimes the anemia is associated from the outset with neutropenia, thrombocytopenia, or both, thus signaling an element of bone marrow failure (see below). Some patients may present with recurrent attacks of severe abdominal pain eventually found to be related to thrombosis in abdominal veins, or attributable to nitric oxide depletion associated with intravascular hemolysis. When thrombosis affects the hepatic vein, it may produce acute hepatomegaly and ascites, i.e., a full-fledged Budd-Chiari syndrome, which, in the absence of liver disease, ought to raise the suspicion of PNH. The natural history of PNH can extend over decades. In the past, with supportive treatment only, the median survival was estimated to be about 10–20 years, with the most common cause of death being venous thrombosis, followed by infection secondary to severe neutro­ penia and hemorrhage secondary to severe thrombocytopenia. Rarely (estimated 1–2% of all cases), PNH may terminate in acute myeloid leukemia. On the other hand, full spontaneous recovery from PNH has been documented, albeit rarely. LABORATORY INVESTIGATIONS AND DIAGNOSIS  The most consistent blood finding is anemia, which may range from mild to moderate to very severe. The anemia is usually normo-macrocytic, with unre­ markable red cell morphology. If the MCV is high, it is usually largely accounted for by reticulocytosis, which may be quite marked (up to 20%, or up to 400,000/μL). The anemia may become microcytic if the patient is allowed to become iron deficient as a result of chronic iron loss through hemoglobinuria. Unconjugated bilirubin is mildly or moderately elevated; LDH is typically markedly elevated (values in the thousands are common); and haptoglobin is usually undetectable. All of these findings make the diagnosis of HA compelling. Hemo­ globinuria may be overt in a random urine sample; if it is not, it may be helpful to obtain serial urine samples because hemoglobinuria can vary dramatically from day to day and even from hour to hour. The bone marrow is usually cellular, with marked to massive erythroid hyperplasia, often with mild to moderate dyserythropoietic features (these overlap with those seen in myelodysplastic syndromes, but PNH remains a separate entity). At some stage of the disease, the marrow may become hypocellular or even frankly aplastic (see below). The definitive diagnosis of PNH must be based on the demonstra­ tion that a substantial proportion of the patient’s red cells are deficient in proteins (notably CD59 and CD55) that normally protect the red cells from activated complement (C). The sucrose hemolysis test is unreliable; in contrast, the acidified serum (Ham) test is highly reliable. The gold standard today is flow cytometry, which can be carried out on granulocytes as well as on red cells and has a very high sensitivity. In PNH, characteristically, one sees a bimodal distribution of cells, with a discrete population that is CD59 and CD55 negative. Although very small populations of CD59(–) cells are of interest in terms of patho­ physiology (particularly of aplastic anemia [AA]), no patient should be diagnosed with PNH unless the proportion is substantial: in first approximation, at least 5% of the total red cells and at least 20% of the total granulocytes. PATHOPHYSIOLOGY  Hemolysis in PNH is mainly intravascular and is due to an intrinsic abnormality of the red cell, which makes it exquisitely sensitive to activated C, whether C is activated through the alternative pathway or through an antigen-antibody reaction (classic pathway). The former mechanism is mainly responsible for chronic hemolysis in PNH; the latter explains why the hemolysis can be dramatically exacerbated in the course of a viral or bacterial infection. Hypersusceptibility to C is due to deficiency in the red cell membrane of several protective proteins (Fig. 105-10), among which CD59 is the most important because it is able to hinder the insertion into the membrane of C9 polymers (the so-called membrane attack complex [MAC]). The molecular basis for the deficiency of these proteins has been pinpointed not to a defect in any of the respective genes, but rather to the shortage of a unique glycolipid molecule, GPI (Fig. 105-2), which, through a peptide bond, anchors these proteins to the surface membrane of cells. The shortage of GPI is due in turn to a somatic mutation in an X-linked gene, called PIGA, required for an early step in GPI biosynthesis. As a result, the patient’s marrow is a mosaic of mutant and nonmutant cells, and the peripheral blood always contains both GPI-negative (PNH) cells and GPI-positive (nonPNH) cells; in most cases, the former prevail. Thrombosis is one of the most immediately life-threatening complications of PNH and yet one of the least understood in its pathogenesis. It could be that deficiency of CD59 on the PNH platelet causes inappropriate platelet activation; however, other mechanisms are possible. In very rare cases, PNH can be caused by biallelic mutations of the autosomal PIGT gene, which maps to chromosome 20q, in the absence of a PIGA mutation. In these cases, because GPI is produced but cannot bind to proteins, the clinical picture is further complicated by the coexistence of a chronic inflam­ matory state. BONE MARROW FAILURE (BMF) AND RELATIONSHIP BETWEEN PNH AND AA  It is not unusual that patients with firmly established PNH have a previous history of AA, sometimes well documented; in many cases, BMF preceding overt PNH may have passed unnoticed, but it is probably the rule rather than the exception. On the other hand, some­ times a patient with PNH becomes less hemolytic and more pancyto­ penic and ultimately has the clinical picture of AA. The relationship between PNH and AA manifested in the clinical course of patients reflects a close link in pathogenesis. AA is thought to be an organspecific autoimmune disease, in which T cells cause damage to hemato­ poietic stem cells via an as yet unidentified molecular target. The same may be true of PNH, and in this condition, the target might be the GPI molecule itself. This would explain why GPI-negative (PNH) stem cells are spared; PIGA mutations can be demonstrated in normal people. Thus, PNH results from the combined action of two factors: failure of normal hematopoiesis and massive expansion of a PNH clone. There is evidence from mouse models that PNH stem cells do not expand on their own, and there is evidence from human patients that expansion is associated with negative selection against GPI-positive cells by GPIspecific T cells. Thus, PNH is a prime example of a clonal disease that is not malignant. Classic pathway Lectin pathway C5 C3 C4b2a C4b2aC3b C5 convertase C3 convertase fD Amplification loop Amplification loop fB C3(H2O)Bb, C3bBb C3 convertases C3BbC3b C5 convertase C5b C3b Alternative pathway C6 C7 CD55 C8 C9 CD59 Normal blood B A Classic pathway Lectin pathway C5 C3 C3 C4b2aC3b C5 convertase C4b2a C3 convertase C4b2a C3 convertase ECULIZUMAB fD Amplification loop Amplification loop fB RAVULIZUMAB C3(H2O)Bb, C3bBb C3 convertases C3BbC3b C5 convertase C5b C3b Alternative pathway C6 C7 C8 Macrophages C9 EXTRAVASCULAR HEMOLYSIS PNH patient, C5 blockade D C FIGURE 105-10  The complement cascade and the fate of red cells. A. In normal blood, when complement is activated, red cells are protected from lysis in several ways: primarily by the two glycosylphosphatidylinositol (GPI)-linked surface proteins CD55 (prevents binding of C3 fragments) and CD59 (prevents the membrane attack complex [MAC] from inserting into the membrane). B. Paroxysmal nocturnal hemoglobinuria (PNH) red cells are deficient in CD55 and CD59 because the glycosylphosphatidylinositol (GPI) biosynthetic pathway is blocked as a result of a PIGA mutation; therefore, C3 fragments, particularly C3d, bind to their surface, and the red cells are rapidly lysed by the action of the MAC. C. With drugs (monoclonal antibodies) that bind to C5 and prevent it from splitting into C5a and C5b, the entire distal pathway from C5 onward is blocked, MAC is not formed, and intravascular hemolysis (IVH) is abrogated. However, red cells opsonized by C3d will be destroyed in the spleen and elsewhere; this drug-induced extravascular hemolysis (EVH) varies in severity between patients. The Coombs test, which is characteristically negative in PNH, becomes positive (provided that a “broadspectrum” or an anticomplement reagent is used). D. With a drug that targets C3, C3b formation is inhibited, and the distal pathway is not triggered by C3b. Therefore, again, no MAC is formed (abrogating IVH), and at the same time, opsonization of red cells by C3d is prevented, so that EVH is also curbed. The same is largely true for drugs that target factor B or factor D, although C3b can still be formed through the classical pathway. (Reproduced with permission from L Luzzatto: Control of hemolysis in patients with PNH. Blood 138:1908, 2021.) TREATMENT Paroxysmal Nocturnal Hemoglobinuria Until around 20 years ago, there were essentially two treatment options for PNH: either allogeneic BMT, providing a definitive cure at the cost of nonnegligible risks; or continued supportive treatment for what, unlike other acquired HAs, may be a lifelong condition. A major advance has been the introduction in 2007 of a humanized Classic pathway Lectin pathway C5 C3 C4b2aC3b C5 convertase C4b2a C3 convertase fD fB C3(H2O)Bb, C3bBb C3 convertases C3BbC3b C5 convertase C5b C3b Alternative pathway C6 C7 C8 C9 MAC MAC INTRAVASCULAR HEMOLYSIS PNH patient CHAPTER 105 Classic pathway Lectin pathway PEGCETACOPLAN C5 Hemolytic Anemias C4b2aC3b C5 convertase fD DANICOPAN fB IPTACOPAN C3(H2O)Bb, C3bBb C3 convertases C3BbC3b C5 convertase C3b C5b Alternative pathway C6 C7 Macrophage C8 C9 MAC MAC PNH patient, C3 blockade monoclonal antibody, eculizumab, which binds to the complement component C5 near the site that, when cleaved, will trigger the distal part of the complement cascade leading to formation of the MAC. With C5 blocked by anti-C5, the patient is relieved of intra­ vascular hemolysis and of its attendant consequences, including hemoglobinuria, with a reduced risk of thrombosis. In the majority of patients who needed regular blood transfusion, the transfusion requirement is either abolished or significantly reduced. For many PNH patient, untreated PNH patient on eculizumab PNH patient on pegcetacoplan A C5 blockade C3 C5 C5 C5 MAC MAC MAC C3 C5 C5 C5 MAC MAC MAC Escape from C5 blockade C5 C5 C5 MAC MAC MAC C3 C5 C5 C5 MAC MAC MAC B PART 4 Oncology and Hematology FIGURE 105-11  Impact and implications of anticomplement therapy in paroxysmal nocturnal hemoglobinuria (PNH). A. The three vertical bars symbolize red cell composition in examples of PNH patients. In the untreated patient, severe anemia is present with ~30% PNH red cells. In the patient on eculizumab, PNH red cells are protected from intravascular hemolysis, although at the expense of iatrogenic extravascular hemolysis (see text), and therefore, mild anemia is still present and can become severe. In the patient on pegcetacoplan, both intravascular and extravascular hemolysis are prevented, and the anemia is completely corrected. Note that the increase in red cells in the treated patients consists entirely of PNH red cells. B. Schematics of complement action and inhibition. In the untreated patient (left), the membrane attack complex (MAC) produces intravascular hemolysis. On eculizumab (middle), C5 blockade prevents MAC formation; if blockade is incomplete, some MAC is formed, with consequent breakthrough hemolysis. On pegcetacoplan (right), C5 convertase cannot be formed, and therefore, MAC formation is equally prevented; however, since there is an enzymatic cascade upstream of C5 cleavage, if blockade is incomplete, MAC formation will be more abundant with consequently more severe breakthrough hemolysis, potentially more massive as the PNH red cells are greatly increased in both relative and absolute terms. RBC, red blood cell. PNH patients, eculizumab has meant a real transformation in the quality of life, as well as a decrease in complications, particularly thrombosis; thrombosis may still occur, but much more rarely. At the same time, it is important to know that in patients on eculi­ zumab, the PNH red cells, now protected from being lysed through the MAC, do still bind C3 fragments and thus become opsonized; thus, the Coombs test becomes positive and hemolysis persists, which is now iatrogenic and mainly extravascular. The extent to which this happens depends in part on a genetic polymorphism of the complement receptor CR1. Based on its half-life, eculizumab must be administered intravenously every 14 days. Ravulizumab, a derivative of eculizumab with longer life in circulation, is adminis­ tered at 8-week intervals, with obvious practical advantage. Patients who, upon C5 blockade, are still receiving blood transfusions are at risk of iron overload. Persistent blood transfusion requirement and extravascular hemolysis in PNH patients on C5 blockade therapy have been a stimulus to developing agents that may inhibit complement activa­ tion more upstream, at the level of C3. This has been found not only to prevent intravascular hemolysis but also to avoid C3 opsoniza­ tion of red cells, thus not causing extravascular hemolysis. Pegce­ tacoplan, an inhibitor of C3, and iptacopan, an inhibitor of factor B (which, once activated, becomes part of the alternative pathway C3 convertase) are already approved drugs; and danicopan, an inhibitor of factor D (required for the activation of factor B), has given promising results in clinical trials. Thus, several drug therapy options are available for an ultra-rare disease (Fig. 105-11). Com­ pared to C5 blockade, C3 blockade has a greater chance to com­ pletely correct anemia. We must consider that correction of anemia takes place by the buildup of a much larger population of PNH red cells than would ever be possible in an untreated PNH patient, and this population may undergo sudden lysis if complement blockade is abrogated, whether by omission or otherwise. Eculizumab and the other complement inhibitors are very expen­ sive and, for this reason, not accessible to patients in many parts of the world. Therefore, the management of PNH by supportive PNH RBC Normal RBC C3 blockade C3 Escape from C3 blockade C5 C5 C5 MAC MAC MAC C3 treatment is still very important. Folic acid supplements (at least 3 mg/d) are mandatory; the serum iron should be checked periodi­ cally, and iron supplements should be administered as appropriate. Transfusion of white cell-free red cells should be used whenever nec­ essary, which, for some patients, means quite frequently. Long-term glucocorticoids are not indicated because there is no evidence that they have any effect on chronic hemolysis; in fact, they are contra­ indicated because their side effects are considerable. A short course of prednisone may be useful when an inflammatory process exacer­ bates hemolysis. Any PNH patient who has had venous thrombosis or who has been found after a thrombophilia screen to have a genetic risk factor should be on regular anticoagulant prophylaxis. With thrombotic complications that do not resolve otherwise, thrombo­ lytic treatment with tissue plasminogen activator may be indicated. Where anti-C5 therapy is available, the proportion of PNH patients receiving BMT has decreased significantly. However, when an HLAidentical sibling is available, BMT should be taken into consideration for any young patient with severe PNH, and for patients with the socalled PNH-AA syndrome, since C inhibitors have no effect on BMF. For these patients, immunosuppressive treatment with antithymocyte globulin and cyclosporine A may be an alternative, and it may be com­ patible with concurrent administration of eculizumab. ■ ■FURTHER READING Berentsen S, Barcellini W: Autoimmune hemolytic anemias. N Engl J Med 385:1407, 2021. Brodsky RA: Warm autoimmune hemolytic anemia. N Engl J Med 381:64, 2019. Dacie J: The Haemolytic Anaemias. London, Churchill Livingstone, volumes 1-5, 1985–1999. De Franceschi L et al: Acute hemolysis by hydroxycloroquine was observed in G6PD-deficient patient with severe COVD-19 related lung injury. Eur J Intern Med 77:136, 2020. Grace RF et al: Safety and efficacy of mitapivat in pyruvate kinase deficiency. N Engl J Med 381:933, 2019. # 36 - 106 Anemia Due to Acute Blood Loss ### 106 Anemia Due to Acute Blood Loss Loirat C et al: An international consensus approach to the manage­ ment of atypical hemolytic uremic syndrome in children. Pediatr Nephrol 31:15, 2016. Luzzatto L et al: Glucose-6-phosphate dehydrogenase deficiency. Blood 136:1225, 2020. Notaro R, Luzzatto L: Breakthrough hemolysis in PNH with proxi­ mal or terminal complement inhibition. N Engl J Med 387:160, 2022. Roy NBA et al: The use of next-generation sequencing in the diagnosis of rare inherited anaemias: A joint BSH/EHA Good Practice Paper. Br J Haematol 198:459, 2022. Uyoga S et al: Glucose-6-phosphate dehydrogenase deficiency and susceptibility to childhood diseases in Kilifi, Kenya. Blood Adv 4:5942, 2020. Dan L. Longo Anemia Due to Acute Blood Loss Blood loss causes anemia by two main mechanisms: (1) by the direct loss of red cells; and (2) if the loss of blood is protracted, it will gradu­ ally deplete iron stores, eventually resulting in iron deficiency. The latter type of anemia is covered in Chap. 102. Here, we are concerned with the former type, that is, posthemorrhagic anemia, which follows acute blood loss. This can be external (e.g., after trauma or obstetric hemorrhage) or internal (e.g., from bleeding in the gastrointestinal tract, rupture of the spleen, rupture of an ectopic pregnancy, sub­ arachnoid hemorrhage, leaking aneurysm). In any of these cases, after the sudden loss of a large amount of blood, there are three clinical/ pathophysiologic stages. (1) At first, the dominant feature is hypovo­ lemia, which poses a threat particularly to organs that normally have a high blood supply, like the brain and the kidneys; therefore, loss of consciousness and acute renal failure are major threats. It is important to note that at this stage an ordinary blood count will not show anemia because the hemoglobin concentration is not affected. As hypovolemia is corrected with intravenous fluids acutely, the hemoglobin will gradu­ ally fall over several hours. On physical exam, tachycardia, tachypnea, decreased pulse pressure, cold skin that appears pale and mottled, and decreased urine output may be noted reflecting the efforts of the sympathetic nervous system to compensate. (2) Next, as an emergency response, baroreceptors and stretch receptors will cause release of vasopressin and other peptides, and the body will shift fluid from the extravascular to the intravascular compartment, producing hemodilu­ tion; thus, the hypovolemia gradually converts to anemia. The degree of anemia will reflect the amount of blood lost. If after 3 days the hemo­ globin is, for example, 7 g/dL, it means that about half of the entire blood has been lost. (3) Provided bleeding does not continue, the bone marrow response will gradually ameliorate the anemia. In this phase of the process, the reticulocyte count and erythropoietin levels will be ele­ vated. The physiologic increase in marrow red cell production reflected by the increase in reticulocytes is similar to the marrow response to hemolysis. Hemolysis and compensatory marrow increase in red blood cell (RBC) production are the two major mechanisms associated with anemia that is accompanied by an increase in reticulocyte count. The diagnosis of acute posthemorrhagic anemia (APHA) is usually straightforward, although sometimes internal bleeding episodes (e.g., after a traumatic injury), even when large, may not be immediately obvious. When the scene is bloody, often the estimate of the volume of blood loss is overestimated. Always check the patient carefully. Look for physical findings that may help localize the bleeding if the site of bleed­ ing is not obvious. Grey Turner sign (flank ecchymosis) may reflect retroperitoneal bleeding. Cullen sign (umbilical ecchymosis) may suggest intraperitoneal or retroperitoneal bleeding. Dullness to chest percussion may suggest intrapleural bleeding. Whenever an abrupt fall in hemoglobin has taken place, whatever history is given by the patient, APHA should be suspected. Supplementary history may have to be obtained by asking the appropriate questions, and appropriate investi­ gations (e.g., a sonogram or an endoscopy) may have to be carried out. If blood loss is mild, enhanced O2 delivery is achieved through changes in the O2–hemoglobin dissociation curve mediated by a decreased pH or increased CO2 (Bohr effect). With acute blood loss, hypovolemia dominates the clinical picture, and the hematocrit and hemoglobin levels do not reflect the volume of blood lost. Signs of vascular instability appear with acute losses of 25% or more of the total blood volume. The donation of a unit of blood (~20% of the blood volume) is often minimally symptomatic. In patients who lose a larger percentage of the blood volume, the issue is not anemia but hypotension and decreased organ perfusion. When >30% of the blood volume is lost suddenly, patients are unable to compensate with the usual mechanisms of sympathetic nervous system increases in heart rate, vascular contraction, and changes in regional blood flow. The patient prefers to remain supine and will show postural hypotension and tachycardia. If the volume of blood lost is >40% (i.e., >2 L in the average-sized adult), signs of hypovolemic shock including confu­ sion, dyspnea, diaphoresis, hypotension, and tachycardia appear. Such patients have significant deficits in vital organ perfusion and require immediate volume replacement. CHAPTER 106 Symptoms associated with more chronic or progressive anemia depend on the age of the patient and the adequacy of blood supply to critical organs. Symptoms associated with moderate anemia include fatigue, loss of stamina, breathlessness, and tachycardia (particularly with physical exertion). However, because of the intrinsic compensa­ tory mechanisms that govern the O2–hemoglobin dissociation curve, the gradual onset of anemia—particularly in young patients—may not be associated with signs or symptoms until the anemia is severe (hemo­ globin <70–80 g/L [7–8 g/dL]). When anemia develops over a period of days or weeks, the total blood volume is normal to slightly increased, and changes in cardiac output and regional blood flow help compen­ sate for the overall loss in O2-carrying capacity. Changes in the posi­ tion of the O2–hemoglobin dissociation curve account for some of the compensatory response to anemia. With chronic anemia, intracellular levels of 2,3-bisphosphoglycerate rise, shifting the dissociation curve to the right and facilitating O2 unloading. This compensatory mechanism can only maintain normal tissue O2 delivery in the face of a 20–30 g/L (2–3 g/dL) deficit in hemoglobin concentration. Finally, further protec­ tion of O2 delivery to vital organs is achieved by the shunting of blood away from organs that are relatively rich in blood supply, particularly the kidney, gut, and skin. Anemia Due to Acute Blood Loss TREATMENT Anemia Due to Acute Blood Loss In patients who are hemodynamically unstable, the usual airway, breathing, and circulation assessments take priority. In the face of bleeding associated with hypotension, pharmacologic support with vasopressors is critical. With respect to anemia treatment, a twopronged approach is imperative. (1) In many cases, the blood lost needs to be replaced promptly. Unlike with many chronic anemias, when finding and correcting the cause of the anemia is the first pri­ ority and blood transfusion may not be even necessary because the body is adapted to the anemia, with acute blood loss, the reverse is true. Because the body is not adapted to the anemia, blood transfu­ sion takes priority. (2) While the emergency is being confronted, it is imperative to stop the hemorrhage and to eliminate its source. In an acute hemorrhage situation, plasma may be preferred to saline for volume expansion since dilution of clotting factors with crystalloid may interfere with hemostasis. Furthermore, trauma can lead to vascular and platelet abnormalities that enhance the bleeding risk. A special type of APHA is blood loss during and immediately after surgery, which can be substantial (e.g., up to 2 L in the case of a # 38 - 108 Polycythemia Vera and Other Myeloproliferative Neoplasms ### 108 Polycythemia Vera and Other Myeloproliferative Neoplasms anti-CD52 monoclonal antibody alemtuzumab are especially effec­ tive in younger MDS patients (<60 years old) with more favorable IPSS. In a consortium retrospective review, about 50% of patients with mainly refractory anemia responded to ATG, usually com­ bined with cyclosporine, particularly patients with hypocellular marrow. HGFs can improve blood counts but, as in most other marrow failure states, have been most beneficial to patients with the least severe pancytopenia. EPO alone or in combination with G-CSF can improve hemoglobin levels, particularly in those with low serum EPO levels who have no or a modest need for transfusions. Sur­ vival is improved by EPO and its amelioration of anemia. G-CSF treatment alone failed to improve survival in a controlled trial. Thrombopoietin mimetics appear to improve platelet counts in some patients, but TPO agonists may increase the rate of leukemic progression in high-risk MDS. No clear evidence suggests that they increase leukemic transformation in low-risk MDS. Luspatercept, which affects transforming growth factor β–mediated suppression of erythropoiesis, has been approved by the FDA for anemia in low-risk MDS, particularly those with SF3B1 mutations. The FDA has approved ivosidenib, an IDH1 inhibitor, for MDS. Venetoclax, a BCL2 inhibitor, is FDA approved for patients with AML and has been used in combination with HMA in high-risk MDS; however, it remains investigational. PART 4 Oncology and Hematology Promising novel agents in trials include targeted therapies (i.e., TP53, splicing factor mutations), inflammation pathway inhibitors (including inflammasome and interleukin 1 receptor–associated kinase), and imetelstat, a telomerase inhibitor. Likely, HMA alone will be replaced with HMA combination therapies. The same principles of supportive care described for aplastic anemia apply to MDS. Many patients will be anemic for years. RBC transfusion support should be accompanied by iron chelation to prevent secondary hemochromatosis. MYELOPHTHISIC ANEMIAS Fibrosis of the bone marrow (see Fig. 65-19), usually accompanied by a characteristic blood smear picture called leukoerythroblastosis, can occur as a primary hematologic disease, called myelofibrosis or myeloid metaplasia (Chap. 108), and as a secondary process, called myelophthi­ sis. Myelophthisis, or secondary myelofibrosis, is reactive. Fibrosis can be a response to invading tumor cells, usually an epithelial cancer of breast, lung, or prostate origin or neuroblastoma. Marrow fibrosis may occur with infection of mycobacteria (both Mycobacterium tuberculosis and Mycobacterium avium), fungi, or HIV and in sarcoidosis. Intracel­ lular lipid deposition in Gaucher disease and obliteration of the mar­ row space related to absence of osteoclast remodeling in congenital osteopetrosis also can produce fibrosis. Secondary myelofibrosis is a late consequence of radiation therapy or treatment with radiomimetic drugs. Usually the infectious or malignant underlying processes are obvious. Marrow fibrosis can also be a feature of a variety of hema­ tologic syndromes, especially chronic myeloid leukemia, multiple myeloma, lymphomas, myeloma, and hairy cell leukemia. The pathophysiology has three distinct features: proliferation of fibroblasts in the marrow space (myelofibrosis); the extension of hema­ topoiesis into the long bones and into extramedullary sites, usually the spleen, liver, and lymph nodes (myeloid metaplasia); and ineffective erythropoiesis. The etiology of the fibrosis is unknown but most likely involves dysregulated production of growth factors: platelet-derived growth factor and transforming growth factor β have been implicated. Abnormal regulation of other hematopoietins would lead to localiza­ tion of blood-producing cells in nonhematopoietic tissues and uncou­ pling of the usually balanced processes of stem cell proliferation and differentiation. Myelofibrosis is remarkable for pancytopenia despite very large numbers of circulating hematopoietic progenitor cells. Anemia is dominant in secondary myelofibrosis, usually normocytic and normochromic. The diagnosis is suggested by the characteristic leukoerythroblastic smear. Erythrocyte morphology is highly abnor­ mal, with circulating nucleated RBCs, teardrops, and shape distortions. WBC numbers are often elevated, sometimes mimicking a leukemoid reaction, with circulating myelocytes, promyelocytes, and myeloblasts. Platelets may be abundant and are often of giant size. Inability to aspi­ rate the bone marrow, the characteristic “dry tap,” can allow a presump­ tive diagnosis in the appropriate setting before the biopsy is decalcified. The course of secondary myelofibrosis is determined by its etiology, usually a metastatic tumor or an advanced hematologic malignancy. Treatable causes must be excluded, especially tuberculosis and fungus. Transfusion support can relieve symptoms. ■ ■FURTHER READING Arber DA et al: International Consensus Classification of myeloid neoplasms and acute leukemias: Integrating morphologic, clinical, and genomic data. Blood 140:1200, 2022. Bernard E et al: Molecular International Prognostic Scoring System for myelodysplastic syndromes. NEJM Evid 1:EVIDoa2200008, 2022. Cazzola M: Myelodysplastic syndromes. N Engl J Med 383:1358, 2020. DeFilipp Z et al: Hematopoietic cell transplantation in the manage­ ment of myelodysplastic syndrome: An evidence-based review from the American Society for Transplantation and Cellular Therapy Committee on Practice Guidelines. Transplant Cell Ther 29:71, 2022. Gurnari C, Maciejewski JP: How I manage acquired pure red cell aplasia in adults. Blood 15;137:2001, 2021. Hellstrom-Lindberg ES et al: Clinical decision-making and treat­ ment of myelodysplastic syndromes. Blood 142:2268, 2023. Khoury JD et al: The 5th edition of the World Health Organization classification of haematolymphoid tumours: Myeloid and histiocytic/ dendritic neoplasms. Leukemia 36:1703, 2022. Mustjoki S, Young NS: Somatic mutations in “benign” disease. N Engl J Med 384:2039, 2021. Townsley DM et al: Eltrombopag added to standard immunosuppres­ sion for aplastic anemia. N Engl J Med 376:1540, 2017. Young NS: Aplastic anemia. N Engl J Med 379:1643, 2018. Jerry L. Spivak Polycythemia Vera and Other Myeloproliferative Neoplasms The World Health Organization (WHO) classification of the chronic myeloproliferative neoplasms (MPNs) includes eight disorders, some of which are rare or poorly characterized (Table 108-1) but all of which share an origin in a hematopoietic stem cell; overproduction of one or more of the formed elements of the blood without significant dysplasia; and a predilection to extramedullary hematopoiesis, myelofibrosis, and transformation at varying rates to acute leukemia. Within this broad TABLE 108-1  World Health Organization Classification of Chronic Myeloproliferative Neoplasms Chronic myeloid leukemia, BCR-ABL–positive Chronic neutrophilic leukemia Chronic eosinophilic leukemia, not otherwise specified Polycythemia vera Primary myelofibrosis Essential thrombocytosis Mastocytosis Myeloproliferative neoplasms, unclassifiable classification, however, significant phenotypic heterogeneity exists. Some diseases such as chronic myelogenous leukemia (CML), chronic neutrophilic leukemia (CNL), and chronic eosinophilic leukemia (CEL) express primarily a myeloid phenotype, whereas in other dis­ eases, such as polycythemia vera (PV), primary myelofibrosis (PMF), and essential thrombocytosis (ET), erythroid or megakaryocytic hyperplasia predominates. The latter three disorders, in contrast to the former three, also appear capable of transforming into each other. Such phenotypic heterogeneity has a genetic basis; CML is the con­ sequence of the balanced translocation between chromosomes 9 and 22 (t[9;22][q34;11]); CNL has been associated with a mutation of CSF3R and a t(15;19) translocation; and CEL occurs with a deletion or bal­ anced translocations involving the PDGFRα usually with the FIP1L1, PDGFRβ, FGFR1, and PCM1-JAK2 genes. By contrast, PV, PMF, and ET are characterized by driver mutations that directly or indirectly constitutively activate JAK2, a tyrosine kinase essential for the function of the erythropoietin and thrombopoietin receptors and also utilized by the granulocyte colony-stimulating factor receptor. This important distinction is reflected in the natural histories of CML, CNL, and CEL, which are usually measured in years, with a high rate of leukemic trans­ formation. The natural histories of PV, PMF, and ET, by contrast, are usually measured in decades, and transformation to acute leukemia is uncommon in the absence of chemotherapy. This chapter focuses only on PV, PMF, and ET because their clinical features and driver mutation overlap are substantial, although their disease duration and clinical manifestations vary. The other chronic MPNs will be discussed in Chaps. 110 and 115. POLYCYTHEMIA VERA PV is a clonal hematopoietic stem cell disorder in which phenotypically normal red cells, granulocytes, and platelets accumulate in the absence of a recognizable physiologic stimulus. The most common of the MPNs, PV occurs in 2.5 per 100,000 persons, sparing no adult age group and increasing with age to rates >10/100,000. Familial transmission is infre­ quent, and women under age 50 predominate among sporadic cases. ■ ■ETIOLOGY Nonrandom chromosome abnormalities such as deletion 20q and deletion 13q or trisomy 9 occur in up to 30% of untreated PV patients, but unlike CML, no consistent cytogenetic abnormality has been asso­ ciated with the disorder. However, a mutation in the autoinhibitory pseudokinase domain of the tyrosine kinase JAK2 that replaces valine with phenylalanine (V617F), causing constitutive kinase activation, has a central role in PV pathogenesis. JAK2 is a member of an evolutionarily well-conserved, nonreceptor tyrosine kinase family and serves as the cognate tyrosine kinase for the erythropoietin and thrombopoietin receptors. It also functions as an obligate chaperone for these receptors in the Golgi apparatus and is responsible for their cell-surface expression. The conformational change induced in the erythropoietin and thrombopoietin receptors following binding to their respective cognate ligands, erythropoi­ etin or thrombopoietin, leads to JAK2 autophosphorylation, receptor phosphorylation, and phosphorylation of proteins involved in cell proliferation, differentiation, and resistance to apoptosis. Transgenic animals lacking JAK2 die as embryos from severe anemia. Constitu­ tive activation of JAK2, on the other hand, explains the erythropoietin hypersensitivity, erythropoietin-independent erythroid colony forma­ tion, rapid terminal differentiation, increased Bcl-XL expression, and apoptosis resistance in the absence of erythropoietin that characterize the in vitro behavior of PV erythroid progenitor cells. More than 95% of PV patients express this mutation, as do ∼50% of PMF and ET patients. Importantly, the JAK2 gene is located on the short arm of chromosome 9, and loss of heterozygosity on chromo­ some 9p involving the segment containing the JAK2 locus over time due to mitotic recombination (uniparental disomy) is the most com­ mon cytogenetic abnormality in PV. Loss of heterozygosity in this region leads to homozygosity for JAK2 V617F and occurs in ∼60% of PV patients and to a lesser extent in PMF but is rare in ET. Most PV patients who do not express JAK2 V617F express a mutation in exon 12 of the gene and are not clinically different from those who do, with the exception of a higher frequency of isolated erythrocytosis, nor do JAK2 V617F heterozygotes differ clinically from homozygotes. Importantly, the predisposition to acquire JAK2 mutations appears to be associated with a specific JAK2 gene haplotype, GGCC. JAK2 V617F is the basis for many of the phenotypic and biochemical characteristics of PV such as increased blood cell production and increased inflammatory cyto­ kine production; however, it cannot solely account for the entire PV phenotype and is probably not the initiating lesion in any of the MPNs. First, PV patients with the same phenotype and documented clonal disease can have mutations in LNK, a JAK2 inhibitor, or rarely, calre­ ticulin (CALR), an ER chaperone, since MPN driver mutations are not mutually exclusive. Second, ET and PMF patients have the same muta­ tions but different clinical phenotypes. Third, familial PV can occur without the mutation, even when other members of the same family express it. Finally, in some JAK2 V617F–positive PV or ET patients, acute leukemia can occur in a JAK2 V617F–negative progenitor cell, suggesting the presence of an ancestral precursor cell. ■ ■CLINICAL FEATURES Although PV is a panmyelopathy, isolated thrombocytosis, leukocy­ tosis, or splenomegaly can be its presenting manifestation, but most often, the disorder is first recognized by the incidental discovery of a high hemoglobin, hematocrit, or red cell count. With the exception of aquagenic pruritus or erythromelalgia, no symptoms distinguish PV from other causes of erythrocytosis. CHAPTER 108 Uncontrolled erythrocytosis causes hyperviscosity, leading to neu­ rologic symptoms such as vertigo, tinnitus, headache, visual distur­ bances, and transient ischemic attacks (TIAs). Systolic hypertension is also a feature of the red cell mass elevation. In some patients, venous or arterial thrombosis may be the presenting manifestation of PV. Any vessel can be affected, but cerebral, cardiac, and mesenteric vessels are most commonly involved. Hepatic venous thrombosis (BuddChiari syndrome) is particularly common in young women and may be catastrophic if sudden and complete obstruction of the hepatic vein occurs; portal vein thrombosis is more common in male PV patients. Indeed, PV should be suspected in any woman who develops hepatic vein thrombosis, since this is the only type of thrombosis associated with JAK2 V617F expression. Digital ischemia, easy bruising, epistaxis, acid-peptic disease, or gastrointestinal hemorrhage may occur due to vascular stasis or extreme thrombocytosis (>900,000/mL). In the lat­ ter instance, absorption and proteolysis of high-molecular-weight von Willebrand multimers by the large platelet mass cause acquired von Willebrand’s disease. Erythema, burning, and pain in the extremities, a symptom complex known as erythromelalgia, is another complication of thrombocytosis in PV due to increased platelet stickiness. Given the large turnover of hematopoietic cells, hyperuricemia with secondary gout, uric acid stones, and symptoms due to hypermetabolism can also complicate the disorder. Polycythemia Vera and Other Myeloproliferative Neoplasms ■ ■DIAGNOSIS When PV presents with erythrocytosis in combination with leukocyto­ sis, thrombocytosis, or splenomegaly or any combination of these, the diagnosis is apparent. However, when patients present with an elevated hemoglobin, hematocrit, and red cell count alone, the diagnostic evalu­ ation is more complex because of the many diagnostic possibilities (Table 108-2). Furthermore, unless the hemoglobin level is ≥20 g/dL (hematocrit ≥60%), it is not possible to distinguish true erythrocytosis from disorders causing plasma volume contraction. This is because uniquely in PV, in contrast to other causes of true erythrocytosis, there is expansion of the plasma volume, which can mask the elevated red cell mass, particularly in women; thus, red cell mass and plasma volume determinations are necessary to establish the presence of an absolute erythrocytosis and distinguish this from relative erythrocyto­ sis due to a reduction in plasma volume alone (also known as stress or spurious erythrocytosis or Gaisböck’s syndrome). Figure 66-18 illustrates a diagnostic algorithm for the evaluation of suspected erythrocytosis. While an assay for JAK2 or rarely LNK mutations in the presence of a normal arterial oxygen saturation appears to provide an alternative TABLE 108-2  Causes of Erythrocytosis Relative Erythrocytosis Hemoconcentration secondary to dehydration, diuretics, ethanol abuse, androgens, or tobacco abuse Absolute Erythrocytosis Hypoxia Tumors Carbon monoxide intoxication Hypernephroma High-oxygen-affinity hemoglobin Hepatoma High altitude Cerebellar hemangioblastoma Pulmonary disease Uterine myoma Right-to-left cardiac or vascular shunts Adrenal tumors Sleep apnea syndrome Meningioma Hepatopulmonary syndrome Pheochromocytoma Renal Disease Drugs Renal artery stenosis Androgens SGLT2 inhibitors Focal sclerosing or membranous glomerulonephritis Recombinant erythropoietin Familial (with normal hemoglobin function) Postrenal transplantation Renal cysts Erythropoietin receptor mutations PART 4 Oncology and Hematology Bartter’s syndrome VHL mutations (Chuvash polycythemia) 2,3-BPG mutation PHD2 (EGLN1) and HIF2α (EPAS1) mutations LNK mutations Polycythemia vera Abbreviations: 2,3-BPG, 2,3-bisphosphoglycerate; VHL, von Hippel-Lindau. diagnostic approach to isolated erythrocytosis since red cell mass and plasma volume determinations are not usually available, isolated eryth­ rocytosis is uncommon as an initial manifestation of PV, and not every­ one expressing a low JAK2 V617F quantitative mutation allele burden (variant allele frequency [VAF] ≤5%) actually has a blood disease. In addition, a normal serum erythropoietin level does not exclude the presence of PV, but an elevated erythropoietin level is most consistent with a secondary cause for the erythrocytosis. Other laboratory studies that may aid in diagnosis include the red cell count, mean corpuscular volume, and red cell distribution width (RDW), particularly when the hematocrit or hemoglobin levels are <60% or 20 g/dL, respectively. Only three situations cause microcytic erythrocytosis: β-thalassemia trait, hypoxic erythrocytosis, and PV. With β-thalassemia trait, the RDW is usually normal, whereas with hypoxic erythrocytosis or PV, the RDW may be elevated due to associ­ ated iron deficiency. Today, however, the quantitative assay for JAK2 V617F or JAK2 exon 12 mutations using next-generation sequencing technology has superseded the other surrogate tests for establishing the diagnosis of PV. A bone marrow aspirate and biopsy provide no specific diagnostic information because these may be normal or indistinguishable from ET or PMF. Similarly, no specific cytogenetic abnormality is associated with the disease, and the absence of a cytogenetic marker does not exclude the diagnosis. ■ ■COMPLICATIONS Many of the clinical complications of PV relate directly to the increase in blood viscosity associated with red cell mass elevation and indirectly to the increased turnover of red cells, leukocytes, and platelets with the attendant increase in uric acid and inflammatory cytokine production. The latter also appears to be responsible for some of the constitutional symptoms in PV. Peptic ulcer disease can also be due to Helicobacter pylori infection, the incidence of which is increased in PV, while the pruritus associated with this disorder may be a consequence of mast cell activation by JAK2 V617F. A sudden increase in spleen size can be associated with painful splenic infarction. Myelofibrosis appears to be part of the natural history of the disease but is a reactive, reversible process that does not itself impede hematopoiesis and by itself has no prognostic significance in PV. In ∼15% of patients, however, myelofi­ brosis is associated with hematopoietic stem cell failure, manifested by substantial extramedullary hematopoiesis in the liver and spleen and transfusion-dependent anemia. Organomegaly can cause significant mechanical discomfort, portal hypertension, and progressive cachexia. Although the incidence of acute myeloid leukemia is increased in PV, the incidence of acute leukemia in patients not exposed to chemo­ therapy or radiation therapy is very low. Interestingly, chemotherapy, including hydroxyurea, has been associated with acute leukemia in JAK2 V617F–negative hematopoietic stem cells (HSCs) in some PV patients. Erythromelalgia is a curious syndrome of unknown etiology associated with thrombocytosis, primarily involving the lower extremi­ ties and usually manifested by erythema, warmth, and pain of the affected appendage and occasionally digital infarction. It occurs with a variable frequency and is usually responsive to salicylates. Some of the central nervous system symptoms observed in patients with PV, such as ocular migraine, appear to represent a variant of erythromelalgia. Left uncontrolled, erythrocytosis can lead to thrombosis involving vital organs such as the liver, heart, brain, or lungs. Patients with mas­ sive splenomegaly are particularly prone to thrombotic events because the associated increase in plasma volume masks the true extent of the red cell mass elevation measured by the hematocrit or hemoglobin level. A “normal” hematocrit or hemoglobin level in a PV patient with massive splenomegaly should be considered indicative of an elevated red cell mass until proven otherwise. TREATMENT Polycythemia Vera PV is generally an indolent disorder, the clinical course of which is measured in decades, and its management should reflect its tempo. Thrombosis due to erythrocytosis is the most significant complication and often the presenting manifestation; maintenance of the hemoglobin level at ≤140 g/L (14 g/dL; hematocrit <45%) in men and ≤120 g/L (12 g/dL; hematocrit <42%) in women is mandatory to avoid thrombotic complications. Phlebotomy serves initially to reduce hyperviscosity by reducing the red cell mass to normal while further expanding the plasma volume. Periodic phlebotomies thereafter serve to maintain the red cell mass within the normal range and induce a state of iron deficiency that prevents accelerated reexpansion of the red cell mass. In most PV patients, once an iron-deficient state is achieved, phlebotomy is usually only required at 3-month intervals. Neither phlebotomy nor iron deficiency increases the platelet count relative to the effect of the disease itself, and neither thrombocytosis nor leukocytosis is cor­ related with thrombosis in PV, in contrast to the strong correlation between erythrocytosis and thrombosis. The use of salicylates to prevent thrombosis in PV patients is potentially harmful not only if the red cell mass is not controlled by phlebotomy, but also due to an increased incidence of bleeding, particularly in patients over age 60. Anticoagulation is indicated when a thrombosis has occurred, and the newer oral anticoagulants may be preferable to a vitamin K antagonist since they do not require monitoring. Asymptomatic hyperuricemia (<10 mg/dL) requires no therapy, but allopurinol should be administered to avoid further elevation of the uric acid when chemotherapy is used to reduce splenomegaly or leukocytosis or to treat pruritus. Generalized pruritus intractable to antihistamines or antidepressants such as doxepin can be a major problem in PV; the JAK1/2 inhibitor ruxolitinib, pegylated interferon α (IFN-α), psoralens with ultraviolet light in the A range (PUVA) therapy, and hydroxyurea are other methods of palliation. Asymptomatic throm­ bocytosis requires no therapy unless the platelet count is sufficiently high to cause bleeding due to acquired von Willebrand’s disease, but bleeding in this situation is not usually spontaneous and is responsive to tranexamic acid or ε-aminocaproic acid. Symptomatic splenomegaly can be treated with either ruxolitinib or pegylated IFN-α. Both ruxolitinib and pegylated IFN-α target the involved HSCs in PV and are not mutagenic; hydroxyurea does not target the involved HSCs in PV and is mutagenic. Furthermore, pegylated IFN-α allows only biweekly administration and produced complete hematologic and molecular remissions in ∼20% of PV patients. Anagrelide, a phosphodiesterase inhibitor, can reduce the platelet count and, if tolerated, is preferable to hydroxyurea because it lacks marrow toxicity and is also protective against venous thrombosis, whereas hydroxyurea is not. However, chronic anagrelide therapy is cardiotoxic and nephrotoxic, particularly in older PV patients. A reduction in platelet number may be necessary for the treat­ ment of erythromelalgia or ocular migraine if salicylates are not effective or if the platelet count is sufficiently high to increase the risk of hemorrhage but only to the degree that symptoms are alleviated. Alkylating agents and radioactive sodium phosphate (32P) are leuke­ mogenic in PV, and their use should be avoided. If a cytotoxic agent must be used, hydroxyurea is preferred, but this drug does not pre­ vent either thrombosis or myelofibrosis in PV, is itself leukemogenic, and should be considered as a short-duration therapy. Previously, PV patients with massive splenomegaly unresponsive to reduction by chemotherapy or IFN required splenectomy. However, with the introduction of the nonspecific JAK1/2 inhibitor ruxolitinib, it has been possible in the majority of patients with PV complicated by myelofibrosis and myeloid metaplasia to reduce spleen size while at the same time alleviating constitutional symptoms and pruritus due to cytokine release while reducing the phlebotomy requirement. However, in contrast to PMF, PV patients have a more chronic course; in contrast to other malignancies, PV patients have a low rate of mutation accumulation, and the acquisition of deleterious mutations such as TP53 mutations as detected by next-generation sequencing is usually associated with leukemic transformation. Since hydroxyurea antagonizes TP53 and also causes del17p, leading to TP53 haploinsufficiency, its chronic use should be constrained in PV. Ruxolitinib has also been demonstrated in a phase 3 clinical trial to be effective in PV patients without myelofibrosis who are intolerant or refractory to hydroxyurea or best available supportive therapy. Three other JAK2 inhibitors, fedratinib, pacritinib, and momelotinib, have been approved for treatment of PV patients with myelofibrosis in whom ruxolitinib treatment failed or who were intolerant to the drug. In some PV patients with end-stage disease, pulmonary hypertension may develop due to fibrosis or extramedullary hematopoiesis. A role for bone marrow transplanta­ tion, either allogeneic or haploidentical, in PV has not been defined. Most patients with PV can live long lives without functional impairment when their red cell mass is effectively managed with phlebotomy alone. Chemotherapy is never indicated to control the red cell mass in PV, but when venous access is an issue, ruxolitinib or pegylated IFN is the preferred therapy. Interestingly, hepcidin production is suppressed, but not absent in PV, and a hepcidin agonist has been shown to reduce phlebotomy requirements in PV. ■ ■PRIMARY MYELOFIBROSIS Chronic PMF (other designations include idiopathic myelofibrosis, agnogenic myeloid metaplasia, or myelofibrosis with myeloid metaplasia) is a clonal HSC disorder associated with mutations in JAK2, MPL, or CALR, and characterized by marrow fibrosis, extramedullary hema­ topoiesis, variable suppression of hematopoiesis, and splenomegaly. PMF is the least common MPN, and establishing its diagnosis in the absence of a specific clonal marker is difficult because myelofibrosis and splenomegaly are also features of both PV and CML. Furthermore, myelofibrosis and splenomegaly also occur in a variety of benign and malignant disorders (Table 108-3), many of which are amenable to specific therapies not effective in PMF. In contrast to the other MPNs and so-called acute or malignant myelofibrosis, which can occur at any age, PMF primarily afflicts men in their sixth decade or later. ■ ■ETIOLOGY Nonrandom chromosome abnormalities such as 9p, 20q−, 13q−, trisomy 8 or 9, or partial trisomy 1q are common in PMF, but no TABLE 108-3  Disorders Causing Myelofibrosis MALIGNANT NONMALIGNANT Acute leukemia (lymphocytic, myelogenous, megakaryocytic) HIV infection Hyperparathyroidism Renal osteodystrophy Systemic lupus erythematosus Tuberculosis Vitamin D deficiency Thorium dioxide exposure Gray platelet syndrome Chronic myeloid leukemia Hairy cell leukemia Hodgkin’s disease Primary myelofibrosis Lymphoma Multiple myeloma Myelodysplasia Metastatic carcinoma Polycythemia vera Systemic mastocytosis cytogenetic abnormality specific to the disease has been identified. JAK2 V617F is present in ∼55% of PMF patients, and mutations in the thrombopoietin receptor, MPL, occur in ~4%. Most of the rest have mutations in the calreticulin gene (CALR) that alter the carboxyterminal portion of the protein, permitting it to bind and activate MPL while presenting it at the cell surface. The degree of myelofibrosis and the extent of extramedullary hematopoiesis are not related. Fibrosis in this disorder is associated with overproduction of transforming growth factor β and tissue inhibitors of metalloproteinases and thrombopoi­ etin, while osteosclerosis is associated with overproduction of osteo­ protegerin, an osteoclast inhibitor. Marrow angiogenesis occurs due to increased production of vascular endothelial growth factor. Impor­ tantly, fibroblasts in PMF are polyclonal and not part of the neoplastic clone but can be induced by it to produce inflammatory cytokines. CHAPTER 108 Polycythemia Vera and Other Myeloproliferative Neoplasms ■ ■CLINICAL FEATURES No signs or symptoms are specific for PMF. Many patients are asymp­ tomatic at presentation, and the disease is often detected by the dis­ covery of splenic enlargement and/or abnormal blood counts during a routine examination. In contrast to its companion MPN, night sweats, fatigue, and weight loss are common presenting complaints. A blood smear will show the characteristic features of extramedullary hemato­ poiesis: teardrop-shaped red cells, nucleated red cells, myelocytes, and promyelocytes; myeloblasts may also be present (Fig. 108-1). Anemia, usually mild initially, is common, whereas the leukocyte and platelet counts are either normal or increased, but either can be depressed. Mild hepatomegaly may accompany splenomegaly but is unusual in its FIGURE 108-1  Teardrop-shaped red blood cells indicative of membrane damage from passage through the spleen, a nucleated red blood cell, and immature myeloid cells indicative of extramedullary hematopoiesis are noted. This peripheral blood smear is related to any cause of extramedullary hematopoiesis. FIGURE 108-2  This marrow section shows the marrow cavity replaced by fibrous tissue composed of reticulin fibers and collagen. When this fibrosis is due to a primary hematologic process, it is called myelofibrosis. When fibrosis is secondary to a tumor or a granulomatous process, it is called myelophthisis. PART 4 Oncology and Hematology absence; isolated lymphadenopathy should suggest another diagnosis. Both serum lactate dehydrogenase and alkaline phosphatase levels can be elevated. Marrow is usually inaspirable due to the myelofibrosis (Fig. 108-2), and bone x-rays may reveal osteosclerosis. Exuberant extramedullary hematopoiesis can cause ascites; portal, pulmonary, or intracranial hypertension; intestinal or ureteral obstruction; pericardial tamponade; spinal cord compression; or skin nodules. Splenic enlarge­ ment can be sufficiently rapid to cause splenic infarction with fever and pleuritic chest pain. Hyperuricemia and secondary gout may ensue. ■ ■DIAGNOSIS While the clinical picture described above is characteristic of PMF, all of these clinical features can be observed in PV or CML. Massive splenomegaly commonly masks erythrocytosis in PV, and reports of intraabdominal thrombosis in PMF most likely represent instances of unrecognized PV. In some PMF patients, erythrocytosis has developed during the course of the disease. Importantly, because many other dis­ orders have features that overlap with PMF but respond to distinctly different therapies, the diagnosis of PMF is one of exclusion, which requires that the disorders listed in Table 108-3 be ruled out. The presence of teardrop-shaped red cells, nucleated red cells, myelocytes, and promyelocytes establishes the presence of extramedul­ lary hematopoiesis, while the presence of leukocytosis, thrombocytosis with large and bizarre platelets, and circulating myelocytes suggests the presence of an MPN as opposed to a secondary form of myelofibrosis (Table 108-3). Marrow is usually inaspirable due to increased marrow reticulin, but marrow biopsy will usually reveal a hypercellular mar­ row with trilineage hyperplasia and, in particular, increased numbers of megakaryocytes in clusters and with large, dysplastic nuclei. A small number of PMF patients with a low JAK2 V617F mutation allele burden (≤25%) have a faster time to anemia and leukopenia and a shortened survival. However, there are no specific bone marrow mor­ phologic abnormalities that distinguish PMF from the other MPNs. Splenomegaly due to extramedullary hematopoiesis may be sufficiently massive to cause portal hypertension and variceal formation. In some patients, exuberant extramedullary hematopoiesis dominates the clini­ cal picture. An intriguing feature of PMF is the occurrence of autoimmune abnormalities such as immune complexes, antinuclear antibodies, rheumatoid factor, or a positive Coombs’ test. Whether these represent a host reaction to the disorder or are involved in its pathogenesis is unknown. Cytogenetic analysis of the blood is useful both to exclude CML and for prognostic purposes, because the development of com­ plex karyotype abnormalities portends a poor prognosis in PMF. It is thought that impaired expression of the cytokine CXCL4 is responsible for the markedly increased number of circulating CD34+ cells in PMF TABLE 108-4  Three Current Scoring Systems for Estimating Prognosis in PMF Patients RISK FACTOR IPSS (2009)a DIPSS (2010)b DIPSS PLUS (2011)c Anemia (<10 g/dL) X X X Leukocytosis (>25,000/μL) X X X Peripheral blood blasts (≥1%) X X X Constitutional symptoms X X X Age (>65 years) X X X Unfavorable karyotype X Platelet count (<100,000/μL) X Transfusion dependence X aBlood 113:2895, 2009. bBlood 115:1703, 2010. cJ Clin Oncol 29:392, 2011. Note: The Dynamic International Prognostic Scoring System (DIPSS) was developed to determine if the International Prognostic Scoring System (IPSS) risk factors identified as important for survival at the time of primary myelofibrosis (PMF) diagnosis could also be used for risk stratification following their acquisition during the course of the disease. One point is assigned to each risk factor for IPSS scoring. For DIPSS, the same is true, but anemia is assigned 2 points. The DIPSS Plus scoring system represents recognition that the addition of unfavorable karyotype, thrombocytopenia, and transfusion dependence improved the DIPSS risk stratification system for which additional points are assigned (Table 108-5). More recent studies suggest that mutational analysis of the ASXL1, EZH2, SRSF2, and IDH1/2 genes further improves risk stratification for survival and leukemic transformation (Leukemia 27:1861, 2013), as can cytogenetic abnormalities (Leukemia 32:1631, 2018). These prognostic scoring systems are not accurate for risk assessment in polycythemia vera or essential thrombocytosis patients who have developed myelofibrosis (Haematologica 99:e55, 2014). (>15,000/μL) compared to PV patients, unless they too develop extra­ medullary hematopoiesis. Importantly, ∼55% of PMF patients, like patients with its companion MPNs, express the JAK2 V617F mutation, often as homozygotes. Such patients are usually older and have higher hematocrits than patients with MPL (4%) or CALR (36%) mutations; PMF patients expressing an MPL mutation tend to be more anemic and have lower leukocyte counts than JAK2 V617F–positive patients. Somatic mutations (due to deletions [type 1] or insertions [type 2]) in exon 9 of CALR have been found in a majority of patients with PMF who lack mutations in either JAK2 or MPL. In some studies, type 1 mutations, the most common CALR mutation in PMF, had a survival advantage compared to JAK2 or MPL mutations but not with respect to leukemic transformation. PMF patients who lack a known MPN driver mutation (triple-negative) appear to have the worst prognosis. ■ ■COMPLICATIONS Survival in PMF varies according to specific risk factors at diagnosis (Tables 108-4 and 108-5) but is much shorter than in PV and ET patients. The natural history of PMF is one of increasing marrow fail­ ure with transfusion-dependent anemia and increasing organomegaly due to extramedullary hematopoiesis. As with CML, PMF can evolve from a chronic to an accelerated phase with constitutional symptoms and increasing marrow failure. About 10% of patients spontaneously transform to an aggressive form of acute leukemia for which therapy is usually ineffective. Additional important prognostic factors for disease acceleration during the course of PMF include the presence of complex TABLE 108-5  IPSS and DIPSS Risk Stratification Systems NUMBER OF RISK FACTORS RISK CATEGORIESa IPSS DIPSS DIPSS PLUS Low Intermediate-1 1–2 Intermediate-2 3–4 2–3 High ≥3 >4 4–6 aThe corresponding survival curves for each risk category can be found in the references cited in the footnotes of Table 108-4. Abbreviations: DIPSS, Dynamic International Prognostic Scoring System; IPSS, International Prognostic Scoring System. cytogenetic abnormalities, thrombocytopenia, and transfusion-dependent anemia. Mutations in the ASXL1, EZH2, SRSF2, and IDH1/2 genes have been identified as risk factors for early death or transformation to acute leukemia, as have complex cytogenetic abnormalities, and have proved to be more useful for PMF risk assessment than the clinical scoring systems. TREATMENT Primary Myelofibrosis No specific therapy exists for PMF. The causes for anemia are mul­ tifarious and include ineffective erythropoiesis uncompensated by splenic extramedullary hematopoiesis, hemodilution due to sple­ nomegaly, splenic sequestration, blood loss secondary to throm­ bocytopenia or portal hypertension, folic acid deficiency, systemic inflammation, and autoimmune hemolysis. Neither recombinant erythropoietin nor androgens such as danazol have proven to be consistently effective as therapy for anemia. Erythropoietin may worsen splenomegaly and will be ineffective if the serum erythro­ poietin level is >125 mU/L. Given the inflammatory milieu that characterizes PMF, glucocorticoids can ameliorate anemia as well as constitutional symptoms such as fever, chills, night sweats, anorexia, and weight loss, and combining these with low-dose thalidomide has proved effective as well. Thrombocytopenia can be due to impaired marrow function, splenic sequestration, or autoimmune destruction and may also respond to low-dose thalidomide and prednisone. Splenomegaly is by far the most distressing and intractable prob­ lem for PMF patients, causing abdominal pain, portal hypertension, easy satiety, and cachexia, whereas surgical removal of a massive spleen is associated with significant postoperative complications including mesenteric venous thrombosis, hemorrhage, rebound leukocytosis and thrombocytosis, and hepatic extramedullary hematopoiesis with no amelioration of either anemia or thrombo­ cytopenia when present. For unexplained reasons, splenectomy also increases the risk of blastic transformation. Splenic irradiation is, at best, temporarily palliative and associ­ ated with a significant risk of neutropenia, infection, and subsequent operative hemorrhage if splenectomy is attempted. Allopurinol can control significant hyperuricemia, and bone pain can be alleviated by local irradiation. Pegylated IFN-α can ameliorate fibrosis in early PMF, but in advanced disease, it may exacerbate bone mar­ row failure. The JAK1/2 inhibitor ruxolitinib has proved effective in reducing splenomegaly and alleviating constitutional symptoms in a majority of advanced PMF patients while possibly prolonging survival, but in some patients, ruxolitinib is associated with RAS mutations. Although anemia and thrombocytopenia are its major side effects, these are dose-dependent, and with time, anemia stabilizes, and thrombocytopenia may improve. Fedratinib, a new tyrosine kinase inhibitor with anti-FLT3 activity, has proved useful in patients with disease refractory to ruxolitinib. Two other JAK2 inhibitors have been approved for PMF therapy, pacritinib, which is useful when thrombocytopenia is present, and momelotinib, which may be useful in improving red cell production. In some patients, hypomethylating agents such as azacytidine or decitabine in combination with high-dose ruxolitinib have been used to control the disease or prepare patients for bone marrow transplantation. Transformation to acute leukemia in PMF, like PV or ET, is usually refractory to treatment. Allogeneic bone marrow transplantation is the only curative treatment for PMF and should be considered in younger patients and older patients with high-risk disease; nonmyeloablative con­ ditioning regimens permit hematopoietic cell transplantation to be extended to older individuals. ESSENTIAL THROMBOCYTOSIS ET (other designations include essential thrombocythemia, idiopathic thrombocytosis, primary thrombocytosis, and hemorrhagic thrombocy­ themia) is a clonal hematopoietic stem cell disorder associated with TABLE 108-6  Causes of Thrombocytosis Tissue inflammation: collagen vascular disease, inflammatory bowel disease Hemorrhage Malignancy Iron-deficiency anemia Infection Surgery Myeloproliferative disorders: polycythemia vera, primary myelofibrosis, essential thrombocytosis, chronic myelogenous leukemia Rebound: Correction of vitamin B12 or folate deficiency, post-ethanol abuse, postsplenectomy Myelodysplastic disorders: 5q– syndrome, idiopathic refractory sideroblastic anemia Hemolysis Postsplenectomy or hyposplenism Familial: Thrombopoietin overproduction, JAK2, CALR, or MPL mutations mutations in JAK2 (V617F), MPL, or CALR and manifested clinically by overproduction of platelets without a definable cause. ET has an incidence of 1–2/100,000 and a distinct female predominance. Canonical MPN driver mutations distinguish 90% of ET patients from the more common nonclonal, reactive forms of thrombocytosis (Table 108-6); mutationnegative ET patients may have either uncommon MPL mutations, JAK2 V617F expression limited to the platelets, or a hereditary form of throm­ bocytosis. Once considered a disease of the elderly and responsible for significant morbidity due to hemorrhage or thrombosis, it is now clear that ET can occur at any age in adults and often without symptoms or dis­ turbances of hemostasis. There is an unexplained female predominance in contrast to PMF or the reactive forms of thrombocytosis where no sex difference exists. Because no specific clonal marker is available, clinical and laboratory criteria have been proposed to distinguish ET from other MPNs, which may also present initially with isolated thrombocytosis but have differing prognoses and therapies (Table 108-6). These criteria are useful in identifying disorders such as CML, PV, PMF, or myelodysplasia, which can masquerade as ET. Furthermore, as with “idiopathic” erythro­ cytosis, nonclonal benign forms of thrombocytosis exist (e.g., hereditary overproduction of thrombopoietin and those with noncanonical JAK2 driver mutations) that are not widely recognized because we currently lack diagnostic assays. Approximately 50% of ET patients express JAK2 V617F, 30% CALR (both type 1 and type 2), and 8% MPL mutations. ET patients lacking a canonical MPN driver mutation usually have a benign prognosis. CHAPTER 108 Polycythemia Vera and Other Myeloproliferative Neoplasms ■ ■ETIOLOGY Megakaryocytopoiesis and platelet production depend on thrombo­ poietin and its receptor MPL. As in the case of early erythroid and myeloid progenitor cells, early megakaryocytic progenitors require the presence of interleukin 3 (IL-3) and stem cell factor for optimal proliferation in addition to thrombopoietin. Their subsequent terminal development is also enhanced by the chemokine stromal cell-derived factor 1 (SDF-1). Interestingly, terminal megakaryocyte maturation and platelet production do not require thrombopoietin. Megakaryocytes are unique among hematopoietic progenitor cells because reduplication of their genome is endomitotic rather than mitotic and promoted by thrombopoietin. Unlike erythropoietin, thrombopoietin is produced only in the liver but has important func­ tions in the bone marrow where it functions to maintain hematopoi­ etic stem cells quiescent in their endosteal niches; once released from their niches, thrombopoietin promotes the proliferation of these cells in the sinusoidal niches. Like plasma erythropoietin and its target erythroblasts, an inverse correlation exists between the platelet count and plasma thrombopoietin. However, unlike erythropoietin, throm­ bopoietin is only constitutively produced and the plasma thrombopoi­ etin level is controlled by the size of the platelet and megakaryocyte progenitor cell pools. Also, in contrast to erythropoietin, but like its myeloid counterparts, granulocyte and granulocyte-macrophage colony-stimulating factors, thrombopoietin not only enhances the proliferation of its target cells but also enhances the reactivity of their end-stage product, the platelet. Paradoxically, in the three MPNs, expression of the thrombopoietin receptor, MPL, is impaired and plasma thrombopoietin is increased despite the increased number of megakaryocytes and platelets. The clonal nature of ET was established by analysis of glucose-6- phosphate dehydrogenase isoenzyme expression in patients hemizy­ gous for this gene. Although thrombocytosis is its principal manifesta­ tion, like the other MPNs, the hematopoietic stem cell is involved in ET. Furthermore, a number of families have been described in which ET was inherited, in one instance as an autosomal dominant trait. In addition to ET, PMF and PV have also been observed in such kindreds. ■ ■CLINICAL FEATURES Clinically, ET is most often identified incidentally when a platelet count is obtained during the course of a routine medical evaluation. Occasionally, review of previous blood counts will reveal that an elevated platelet count was present but overlooked for many years. No symptoms or signs are specific for ET, but these patients can have hemorrhagic and thrombotic tendencies expressed as easy bruising for the former and microvascular occlusive events for the latter such as erythromelalgia, ocular migraine, or a TIA. Physical examination is generally unremarkable. Splenomegaly is indicative of another MPN, in particular PV, PMF, or CML. Anemia is unusual, but a mild neutrophilic leukocytosis is not. The blood smear is most remarkable for the number of platelets pres­ ent, some of which may be very large. The large mass of circulating platelets may prevent the accurate measurement of serum potassium due to release of platelet potassium upon blood clotting. This type of hyperkalemia is a test tube artifact and not associated with electrocar­ diographic abnormalities. Similarly, arterial oxygen measurements can be inaccurate unless thrombocythemic blood is collected on ice. The prothrombin and partial thromboplastin times are normal, whereas abnormalities of platelet function such as a prolonged bleeding time and impaired platelet aggregation can be present. However, despite much study, no platelet function abnormality is characteristic of ET, and no platelet function test predicts the risk of clinically significant bleeding or thrombosis. PART 4 Oncology and Hematology The elevated platelet count may hinder marrow aspiration, but marrow biopsy usually reveals megakaryocyte hypertrophy and hyper­ plasia, as well as an overall increase in marrow cellularity. If marrow reticulin is increased, another diagnosis should be considered. The absence of stainable iron demands an explanation because iron defi­ ciency alone can cause thrombocytosis, and absent marrow iron in the presence of marrow hypercellularity is a feature of PV. Nonrandom cytogenetic abnormalities occur in ET but are uncom­ mon, and no specific or consistent abnormality is notable, even those involving chromosomes 3 and 1, where the genes for thrombopoietin and its receptor, MPL, respectively, are located. ■ ■DIAGNOSIS Thrombocytosis is encountered in a broad variety of clinical disorders (Table 108-6), in many of which inflammatory cytokine production is increased. The absolute level of the platelet count is not a useful diagnostic aid for distinguishing between benign and clonal causes of thrombocytosis. About 50% of ET patients express the JAK2 V617F mutation. When JAK2 V617F is absent, cytogenetic evaluation is man­ datory to determine if the thrombocytosis is due to CML or a myelo­ dysplastic disorder such as the 5q– syndrome or sideroblastic anemia. Because the BCR-ABL translocation can be present in the absence of the Ph chromosome, and because the BCR-ABL reverse transcriptase polymerase chain reaction is associated with false-positive results, fluorescence in situ hybridization (FISH) analysis for BCR-ABL is the preferred assay in patients with thrombocytosis in whom a cytogenetic study for the Ph chromosome is negative. CALR mutations (type 1 or type 2) are present in 30% and MPL mutations are present in 8% of ET patients who do not have a JAK2 mutation. Anemia and ringed sideroblasts are not features of ET, but they are features of idiopathic refractory sideroblastic anemia with the SF3B1 mutation, and in some of these patients, thrombocytosis occurs in association with expression of JAK2 V617F, CALR, or an MPL mutation. Significant splenomegaly should suggest the presence of another MPN such as PV or PMF, because splenomegaly can mask the presence of erythrocyto­ sis. Importantly, what appears to be ET can evolve into PV (usually in women with JAK2 V617F) or PMF (usually in men with type 1 CALR mutations) after a period of many years due to clonal evolution or succession. There is sufficient overlap of the JAK2 V617F neutrophil allele burden between ET and PV that this test cannot be used as a dis­ tinguishing diagnostic feature with the exception that, in ET, the quan­ titative JAK2 V617F neutrophil allele is never greater than 50%, and importantly in this regard, 64% of JAK2 V617F–positive ET patients in one study actually were found to have PV when red cell mass and plasma volume determinations were performed. Claims that ET and PV form a biological continuum are unfounded as these disorders have different gene expression profiles and different natural histories. ■ ■COMPLICATIONS Perhaps no other condition in clinical medicine has caused otherwise astute physicians to intervene inappropriately more often than throm­ bocytosis, particularly if the platelet count is >1 × 106/μL. It is com­ monly believed that a high platelet count causes thrombosis; however, no controlled clinical study has ever established this association, and in patients younger than age 60 years, the incidence of thrombosis was not greater in patients with thrombocytosis than in age-matched controls, and tobacco use appears to be the most important risk factor for thrombosis in ET patients. To the contrary, very high platelet counts are associated primarily with hemorrhage due to acquired von Willebrand’s disease. This is not meant to imply that an elevated platelet count cannot cause symptoms in an ET patient, but rather that the focus should be on the patient, not the platelet count. For example, some of the most dramatic neurologic problems in ET are migraine-related and respond only to lowering of the platelet count, whereas other symptoms such as erythromelalgia respond simply to platelet cyclooxygenase-1 inhibitors such as aspirin or ibuprofen, without a reduction in platelet number. Still others may represent an interaction between an atherosclerotic vascular system and a high platelet count, and others may have no relationship to the platelet count whatsoever. Recognition that PV can present with thrombocytosis alone as well as the discovery of previously unrecog­ nized causes of hypercoagulability (Chaps. 121 and 122) make the older literature on the complications of thrombocytosis unreliable. TREATMENT Essential Thrombocytosis Survival of ET patients is not different than the general population regardless of their driver mutation. An elevated platelet count in an asymptomatic patient without cardiovascular risk factors or tobacco use requires no therapy. Indeed, before any therapy is initi­ ated in a patient with thrombocytosis, the cause of symptoms must be clearly identified as due to the elevated platelet count. When the platelet count rises above 1 × 106/μL, a substantial quantity of high-molecular-weight von Willebrand multimers are removed from the circulation and destroyed by the enlarged platelet mass, resulting in an acquired form of von Willebrand’s disease. This can be identified by a reduction in ristocetin cofactor activity. In this situation, aspirin could promote hemorrhage. Bleeding in this situ­ ation is rarely spontaneous and usually responds to tranexamic acid or ε-aminocaproic acid, which can be given prophylactically before and after elective minor surgery. Plateletpheresis is at best a temporary and inefficient remedy that is rarely required. Importantly, ET patients treated with 32P or alkylating agents are at risk of developing acute leukemia without any proof of benefit; combining either therapy with hydroxyurea increases this risk. If platelet reduction is deemed necessary on the basis of symptoms refractory to salicylates alone, pegylated IFN-α, the quinazoline derivative anagrelide, or hydroxyurea can be used to reduce the platelet count, but none of these is uniformly effec­ tive or without significant side effects. Hydroxyurea and aspirin # 39 - 109 Acute Myeloid Leukemia ### 109 Acute Myeloid Leukemia were more effective than anagrelide and aspirin for prevention of TIA because hydroxyurea is a nitric oxide donor, but they were not more effective for the prevention of other types of arterial throm­ bosis and actually less effective for venous thrombosis. The risk of gastrointestinal bleeding is also higher when aspirin is combined with anagrelide. Normalizing the platelet count does not prevent either arterial or venous thrombosis. Pegylated IFN can produce a complete molecular remission in some ET patients, but a role for it or ruxolitinib in ET management has not yet been established. As more clinical experience is acquired, ET appears more benign than previously thought. Evolution to acute leukemia is more likely to be a consequence of therapy than of the disease itself. In manag­ ing patients with thrombocytosis, the physician’s first obligation is to do no harm. ■ ■FURTHER READING Alvarez-Larran A et al: Antiplatelet therapy versus observation in low-risk essential thrombocythemia with CALR mutation. Haema­ tologica 101:926, 2016. Guglielmelli P et al: Clinical impact of mutated JAK2 allele burden reduction in polycythemia vera and essential thrombocythemia. Am J Hematol 99:1550, 2024. Passamonti F et al: Myelofibrosis. Blood 141:1954, 2023. Spivak JL: How I treat polycythemia vera. Blood 134:341, 2019. Wouters HJCM et al: Erythrocytosis in the general population: Clinical characteristics and association with clonal hematopoiesis. Blood Adv 4:6353, 2020. William Blum Acute Myeloid Leukemia INCIDENCE Acute myeloid leukemia (AML) is a neoplasm characterized by infil­ tration of the blood, bone marrow, and other tissues by proliferative, clonal, poorly differentiated cells of the hematopoietic system. These leukemias comprise a spectrum of malignancies that untreated are uniformly fatal. In 2023, the estimated number of new AML cases in the United States was 20,380. AML is the diagnosis in 1% of all cancer cases and 31% of all new acute leukemias but causes 62% of leukemic deaths. AML is the most common acute leukemia in older patients, with a median age at diagnosis of 69 years. U.S. registry data report that only 32% of patients survive 5 years. ■ ■ETIOLOGY Most cases of AML are idiopathic. Genetic predisposition, radiation, chemical/other occupational exposures, and drugs have been impli­ cated in the development of AML, but AML with established etiology is relatively uncommon. No direct evidence suggests a viral etiology. Genome sequencing studies suggest that most cases of AML arise from a limited number of mutations that accumulate with advancing age. Indeed, genome sequencing provides paradigm-shifting advances in our understanding of leukemogenesis. The Cancer Genome Atlas (TCGA) and other databases demonstrate that blood cells from up to 5–6% of normal individuals aged >70 years contain potentially “prema­ lignant” mutations that are associated with clonal expansion. Use of the term premalignant to describe these lesions is not pre­ cisely accurate; rather, these mutations represent clonal hematopoiesis of indeterminate potential (CHIP; sometimes called age-related clonal hematopoiesis). The genes most commonly mutated in CHIP are the epigenetic regulators DNMT3A, TET2, and ASXL1. Study of CHIP is important because it has relevance not just to blood cancer evolution but also other medical conditions. Clonal expansion driven by the acquisition of new mutations is associated with a 10-fold increase in risk for developing a hematologic malignancy (compared to matched patients without CHIP), but it is clear that additional “hits” must occur to drive toward leukemia. We do not yet fully understand why or how these secondary lesions occur. Patients with CHIP also have increased risk of cardiovascular mor­ tality that is not fully explained. The link between these two seemingly unrelated issues (cardiovascular and hematologic malignancy) may lie in the interactions between circulating clonally expanded blood cells and vascular endothelium. A “proinflammatory” state caused by clonal, infiltrating monocytes leads to accelerated atherosclerotic plaque development and altered cardiac remodeling. Similar phenom­ ena may occur in the marrow/blood. An altered relationship between hematopoietic stem cells and the marrow microenvironment (along with altered immune surveillance) contributes to clonal survival and expansion. These perturbations increase the likelihood that a clone with somatic mutations may survive, acquire additional mutations, and then further expand eventually to leukemia. Whether early identi­ fication of CHIP in patients will provide therapeutic opportunities for patients remains to be seen. Certainly, modifying cardiovascular risk in patients with CHIP seems prudent, but development of mutationdirected therapy designed to eliminate a problematic clone and prevent future leukemia is likely to be more elusive. CHAPTER 109 Genetic Predisposition  Myeloid neoplasms occur sporadically in adults; inherited predisposition is uncommon. Yet, it is clear that myeloid neoplasms with germline predisposition represent an impor­ tant and growing subset of disease. Germline mutations associated with increased risk of developing a myeloid neoplasm include CEBPA, DDX41, TP53, RUNX1, ANKRD26, ETV6, and GATA2, and others (Table 109-1). Myeloid neoplasms with germline predisposition are Acute Myeloid Leukemia TABLE 109-1  World Health Organization 2022, Subtypes of Myeloid Neoplasms Associated with Germline Predisposition Myeloid neoplasms with germline predisposition without a preexisting platelet disorder or organ dysfunction • Germline CEBPA P/LP variant (CEBPA-associated familial AML) • Germline DDX41 P/LP varianta • Germline TP53 P/LP varianta (Li-Fraumeni syndrome) Myeloid neoplasms with germline predisposition and preexisting platelet disorder • Germline RUNX1 P/LP varianta (familial platelet disorder with associated myeloid malignancy [FPD-MM]) • Germline ANKRD26 P/LP varianta (thrombocytopenia 2) • Germline ETV6 P/LP varianta (thrombocytopenia 5) Myeloid neoplasms with germline predisposition and potential organ dysfunction • Germline GATA2 P/LP variant (GATA2 deficiency) • Bone marrow failure syndromes • Severe congenital neutropenia (SCN) • Shwachman-Diamond syndrome (SDS) • Fanconi anemia (FA) • Telomere biology disorders • RASopathies (neurofibromatosis type 1, CBL syndrome, Noonan syndrome or Noonan syndrome-like disordersa) • Down syndromea • Germline SAMD9 P/LP variant (MIRAGE syndrome) • Germline SAMD9L P/LP variant (SAMD9L-related ataxia pancytopenia syndrome)b • Biallelic germline BLM P/LP variant (Bloom syndrome) aLymphoid neoplasms can also occur. bAtaxia is not always present. Abbreviations: LP, likely pathogenic; P, pathogenic. Source: Modified from JD Khoury et al: The 5th edition of the World Health Organization Classification of Haematolymphoid Tumours: Myeloid and histiocytic/ dendritic neoplasms. Leukemia 36:1703, 2022. a feature of several well-described clinical syndromes, including bone marrow failure disorders (e.g., Fanconi anemia, Shwachman-Diamond syndrome, Diamond-Blackfan anemia) and telomere biology disorders (e.g., dyskeratosis congenita). As new mutations and associations are added to a rapidly growing list, it is clear that genetic predisposition plays a larger role than has been previously understood. Several genetic syndromes with somatic cell chromosome aneu­ ploidy, such as Down syndrome with trisomy 21, are associated with an increased incidence of AML. Down syndrome–associated AML in young children (<4 years) is typically of megakaryocytic differentiation and is associated with mutation in the GATA1 gene. Such patients have excellent clinical outcomes but require dose modification of chemo­ therapy due to high treatment-related toxicities. Inherited diseases with defective DNA repair (e.g., Fanconi anemia, Bloom syndrome, and ataxia-telangiectasia) are also associated with AML. Each syndrome is associated with unique clinical features and atypical toxicities with che­ motherapy, requiring expert care. Congenital neutropenia (Kostmann syndrome), due to mutations in the genes encoding the granulocyte colony-stimulating factor receptor and neutrophil elastase, is another disorder that may evolve into AML. Chemical, Radiation, and Other Exposures  Anticancer drugs are the leading cause of therapy-associated AML. AML post chemo­ therapy (AML-pCT) with alkylating agents occurs 4–6 years after exposure; affected individuals often have multilineage dysplasia, monosomy/aberrations in chromosomes 5 and 7, mutations of TP53, and poor prognosis. AML-pCT with topoisomerase II inhibitors occurs 1–3 years after exposure; affected individuals often have AML with monocytic features and aberrations involving chromosome 11q23 (involved gene previously called MLL, now KMT2A). The risk of acute leukemia is much higher after combined-modality therapy with alkyl­ ating agent–based chemotherapy plus external beam radiation therapy. Exposure to ionizing radiation, benzene, chloramphenicol, phenylbu­ tazone, and other drugs can result in bone marrow failure that may evolve into AML. PART 4 Oncology and Hematology ■ ■CLASSIFICATION Historically, marrow (or blood) myeloid blast count of ≥20% estab­ lished the diagnosis of AML. However, biologically distinct groups are now primarily classified based on genetic aberrations, in addition to clinical features and light microscopy. It is increasingly understood that genetic aberrations drive clinical presentation and clinical course, and thus, in 2022, the World Health Organization (WHO) eliminated the blast percent requirement among cases with specific, defined genetic aberrations (Table 109-2). In the WHO system referenced here, genetic aberrations are notated by the gene mutation or fusion involved; learners may find clarity by also reviewing the European LeukemiaNet (ELN) risk classification (Table 109-3), which lists asso­ ciated cytogenetic abnormalities alongside the gene fusions. Dueling classification systems of the WHO and the International Consensus Classification (ICC) assign AML diagnosis inconsistently with regard to blast percent, but the differences are semantic. Cases with <20% blasts that are still classified as AML have recurrent genetic abnor­ malities including t(15;17), t(8;21), inv(16), t(16;16), rearrangements involving KMT2A (with many different fusion partners), mutations in NPM1 (nucleophosmin), and other defined genetic aberrations. The emergence of novel targeted treatment options for specific aberrations, such as menin inhibitors for patients with KMT2A rearrangement, NPM1 mutation, or (possibly) NUP98 rearrangement, suggests that a practical approach to classification based on the presence of a specific aberration regardless of blast count may indeed be most appropriate. All AML cells contain genetic mutations, most of which are recurring; in 2024, the majority of AML patients will have a genetic lesion that can be specifically targeted with a novel drug. Genetic Findings  Subtypes of AML are recognized due to the presence or absence of specific, recurrent cytogenetic, and/or genetic abnormalities. For example, the diagnosis of acute promy­ elocytic leukemia (APL) is based on the presence of the t(15;17) TABLE 109-2  World Health Organization 2022 Classification of Acute Myeloid Leukemia Acute myeloid leukemia with defining genetic abnormalities   Acute promyelocytic leukemia with PML::RARA fusion   Acute myeloid leukemia with RUNX1::RUNX1T1 fusion   Acute myeloid leukemia with CBFB::MYH11 fusion   Acute myeloid leukemia with DEK::NUP214 fusion   Acute myeloid leukemia with RBM15::MRTFA fusion   Acute myeloid leukemia with BCR::ABL1 fusiona   Acute myeloid leukemia with KMT2A rearrangement   Acute myeloid leukemia with MECOM rearrangement   Acute myeloid leukemia with NUP98 rearrangementb   Acute myeloid leukemia with NPM1 mutation   Acute myeloid leukemia with CEBPA mutationa,c   Acute myeloid leukemia, myelodysplasia-relateda,d   Acute myeloid leukemia with other defined genetic alterationsa Acute myeloid leukemia, defined by differentiation   Acute myeloid leukemia with minimal differentiation   Acute myeloid leukemia without maturation   Acute myeloid leukemia with maturation   Acute basophilic leukemia   Acute myelomonocytic leukemia   Acute monocytic leukemia   Acute erythroid leukemia   Acute megakaryoblastic leukemia aRequires ≥20% blasts. bNUP98 rearrangements involve 11p15, with many fusion partners, usually cryptic on cytogenetic analysis. cIncludes biallelic (biCEBPA) as well as single mutations located in the basic leucine zipper (bZIP) region. dDefining characteristics of Acute myeloid leukemia, myelodysplasia-related (AML-MR) include history of myelodysplastic syndrome (MDS) or MDS/myeloproliferative neoplasm (MPN) and/or one of the following: complex karyotype, several other specific chromosome aberrations typical of MDS, or mutation of ASXL1, BCOR, EZH2, SF3B1, SRSF2, STAG2, U2AF1, or ZRSR2. Source: Modified from JD Khoury et al: The 5th edition of the World Health Organization Classification of Haematolymphoid Tumours: Myeloid and histiocytic/ dendritic neoplasms. Leukemia 36:1703, 2022. (q22;q12) cytogenetic rearrangement or the PML-RARA fusion. Simi­ larly, core binding factor (CBF) AML is designated based on the pres­ ence of t(8;21)(q22;q22), inv(16)(p13.1q22), or t(16;16)(p13.1;q22) or the respective fusion products RUNX1-RUNX1T1 and CBFB-MYH11. Each of these three groups identifies patients with favorable clinical outcomes when appropriately treated. Many genetic AML subtypes are associated with a specific mor­ phologic appearance such as a complex karyotype (and/or mutation of TP53) and dysplastic morphology in AML, myelodysplasia-related (AML-MR). One abnormality is invariably associated with a spe­ cific morphologic feature: t(15;17)(q22;q12) or the molecular fusion PML-RARA with APL. Further examples include inv(16)(p13.1q22) with AML and abnormal bone marrow eosinophils; t(8;21)(q22;q22) and slender Auer rods, expression of CD19, and increased normal eosinophils; and rearrangements involving KMT2A with monocytic features. AML with mutation of NPM1, especially when co-occurring with mutation of FLT3 (fms-related tyrosine kinase 3), often pres­ ents with blasts having “cup-shaped” nuclear morphology. Recurring genetic aberrations in AML may also be loosely associated with spe­ cific clinical characteristics. More commonly associated with younger age are t(8;21) and t(15;17), and with older age are del(5q), del(7q), and mutated TP53. Myeloid sarcomas are associated with t(8;21); dis­ seminated intravascular coagulation (DIC) is associated with t(15;17). KMT2A aberrations and monocytic leukemia are associated with extramedullary sites of involvement at presentation, especially gingival hypertrophy. High leukocyte count is commonly observed with NPM1 and/or FLT3 mutation. Many other cytogenetic and genetic findings commonly, but not always, are associated with a morphologic descrip­ tion, highlighting the necessity of genetic and cytogenetic testing for precise diagnosis. TABLE 109-3  2022 European LeukemiaNet Risk Classification of Acute Myeloid Leukemia (AML) by Genetics at Initial Diagnosisa RISK CATEGORY GENETIC ABNORMALITY Favorable • t(8;21)(q22;q22.1)/RUNX1::RUNX1T1b,c • inv(16)(p13.1q22) or t(16;16)(p13.1;q22)/CBFB::MYH11b,c • Mutated NPM1b,d without FLT3-ITD • bZIP in-frame mutated CEBPAe Intermediate • Mutated NPM1b,d with FLT3-ITD • Wild-type NPM1 with FLT3-ITD (without adverse-risk genetic lesions) • t(9;11)(p21.3;q23.3)/MLLT3::KMT2Ab,f • Cytogenetic and/or molecular abnormalities not classified as favorable or adverse Adverse • t(6;9)(p23.3;q34.1)/DEK::NUP214 • t(v;11q23.3)/KMT2A-rearrangedg • t(9;22)(q34.1;q11.2)/BCR::ABL1 • t(8;16)(p11.2;p13.3)/KAT6A::CREBBP • inv(3)(q21.3q26.2) or t(3;3)(q21.3;q26.2)/GATA2, MECOM(EVI1) • t(3q26.2;v)/MECOM(EVI1)-rearranged • −5 or del(5q); −7; −17/abn(17p) • Complex karyotype,h monosomal karyotypei • Mutated ASXL1, BCOR, EZH2, RUNX1, SF3B1, SRSF2, STAG2, U2AF1, and/or ZRSR2j • Mutated TP53k aFrequencies, response rates, and outcome measures should be reported by risk category and, if sufficient numbers are available, by specific genetic lesions indicated. Acute promyelocytic leukemia is excluded from this table. bMainly based on results observed in intensively treated patients. Initial risk assignment may change during the treatment course based on the results from analyses of measurable residual disease. cConcurrent KIT and/or FLT3 gene mutation does not alter risk categorization. dAMLs with NPM1 mutation and adverse-risk cytogenetic abnormalities are categorized as adverse risk. eOnly in-frame mutations affecting the basic leucine zipper (bZIP) region of CEBPA, irrespective of whether they occur as monoallelic or biallelic mutations, have been associated with favorable outcome. fThe presence of t(9;11)(p21.3;q23.3) takes precedence over rare, concurrent adverse-risk gene mutations. gExcluding KMT2A partial tandem duplication (PTD). hComplex karyotype: three or more unrelated chromosome abnormalities in the absence of other class-defining recurring genetic abnormalities; excludes hyperdiploid karyotypes with three or more trisomies (or polysomies) without structural abnormalities. iMonosomal karyotype: presence of two or more distinct monosomies (excluding loss of X or Y), or one single autosomal monosomy in combination with at least one structural chromosome abnormality (excluding corebinding factor AML). jFor the time being, these markers should not be used as an adverse prognostic marker if they co-occur with favorable-risk AML subtypes. kTP53 mutation at a variant allele fraction of at least 10%, irrespective of the TP53 allelic status (mono- or biallelic mutation); TP53 mutations are significantly associated with AML with complex and monosomal karyotype. Source: Reproduced with permission from H Döhner et al: Diagnosis and management of AML in adults: 2022 recommendations from an international expert panel on behalf of the ELN. Blood 140:1345, 2022. WHO classification incorporates molecular abnormalities by rec­ ognizing fusion genes or specific genetic mutations with a role in leu­ kemogenesis. As a classic example, t(15;17) results in the fusion gene PML-RARA that encodes a chimeric protein, promyelocytic leukemia (Pml)–retinoic acid receptor α (Rarα), which is formed by the fusion of the retinoic acid receptor α (RARA) gene from chromosome 17 and the promyelocytic leukemia (PML) gene from chromosome 15. Unique clinical therapy with retinoic acid and arsenic trioxide has revolution­ ized the care of APL patients (see “Treatment of Acute Promyelocytic Leukemia” section). Similar examples of molecular subtypes included in the category of AML with recurrent genetic abnormalities are those characterized by the leukemogenic fusion genes RUNX1-RUNX1T1 and CBFB-MYH11 and the so-called CBF AML subtypes noted cytogenetically as t(8;21), inv(16), or t(16;16). Additional examples of fusions are MLLT3-KMT2A and DEK-NUP214, resulting from t(9;11) and t(6;9)(p23;q34). Mutated genes are also critical elements of AML classification. The most common is AML with mutated NPM1, a mutation seen in 30% of AML patients and in 60% of those with cytogenetically normal AML (CN-AML). Another subtype is AML with mutated CEBPA (specifically in-frame bZIP mutation). Both are associated with more favorable clinical outcomes, though the presence of coexisting mutation in FLT3 negatively affects NPM1 prognostic impact. Activating mutations of FLT3 are present in ∼30% of adult AML patients, primarily due to internal tandem duplications (ITDs) in the juxtamembrane domain that have negative prognostic impact. In contrast, point mutations of the activating loop of the kinase, called tyrosine kinase domain (TKD) mutations, have uncertain prognostic impact. Aberrant activation of the FLT3-encoded protein provides increased proliferation and antiapoptotic signals to the myeloid pro­ genitor cell. FLT3-ITD, the most common of the FLT3 mutations, also occurs preferentially in patients with CN-AML. The importance of identifying FLT3-ITD at diagnosis relates to the fact that it is not only useful as a negative prognosticator but also predicts response to specific treatment such as a tyrosine kinase inhibitor (TKI). Several TKIs targeting FLT3 are either approved for AML (e.g., midostaurin or quizartinib, only in first-line therapy in combination with chemo­ therapy; gilteritinib, in relapse as monotherapy) or currently in clinical investigation. Immunophenotypic Findings  The immunophenotype of human leukemia cells can be studied by multiparameter flow cytom­ etry after the cells are labeled with monoclonal antibodies to cellsurface antigens. This can be important in quickly distinguishing AML from acute lymphoblastic leukemia and for identifying some subtypes of AML. For example, AML with minimal differentiation, character­ ized by immature morphology and no lineage-specific cytochemical reactions, may be diagnosed by flow-cytometric demonstration of the myeloid-specific antigens cluster designation (CD) 13 and/or 117. Similarly, acute megakaryoblastic leukemia can often be diagnosed only by expression of the platelet-specific antigens CD41 and/or CD61. Although flow cytometry is widely used, and in some cases essential for the diagnosis of AML, it has only a supportive role in establishing the different subtypes of AML through the WHO classification given the paramount importance of genetics. Increasingly, multiparameter flow cytometry is used for the measurement of measurable residual disease (MRD) after remission is achieved. CHAPTER 109 Acute Myeloid Leukemia ■ ■PROGNOSTIC FACTORS Several factors predict outcome of AML patients treated with che­ motherapy; they should be used for risk stratification and treatment guidance. Chromosome and molecular investigations performed at diagnosis provide the most important prognostic information. Patients with t(15;17) have a very good prognosis (∼85% cured), and those with t(8;21) and inv(16) have a good prognosis (∼55% cured), whereas those with no cytogenetic abnormality have an intermediate outcome risk (∼40% cured). Patients with NPM1 mutation without a FLT3-ITD also have favorable risk and high cure rate; conversely, those with TP53 mutation, complex karyotype, t(6;9), inv(3), or –7 have adverse risk and very poor clinical outcomes with virtually no chance for cure without transplantation. For patients lacking prognostic cytogenetic abnormalities, i.e., those with CN-AML, testing for several mutated genes can help to risk-stratify. In addition to NPM1 mutation and FLT3-ITD as described above, in-frame bZIP CEBPA mutation has favorable prognosis. Given the proven prognostic importance of NPM1, FLT3, and CEBPA, molecular assessment of these genes and others at diagnosis has been incorpo­ rated into AML management guidelines by the National Comprehen­ sive Cancer Network (NCCN) and the ELN. The same markers help to define genetic groups in the ELN standardized reporting system, which is based on both cytogenetic and molecular abnormalities and is used for comparing clinical features/treatment response among subsets of patients reported across different clinical studies (Table 109-3). These genetic groups should be used for risk stratification and treatment guidance (note that APL is excluded from the table). In addition to NPM1, FLT3, CEBPA, and TP53 mutations, molecu­ lar aberrations in other genes are routinely used for prognostication. Among these mutated genes are those encoding receptor tyrosine kinases, transcription factors (RUNX1 and WT1), and epigenetic modifiers (ASXL1, DNMT3A, isocitrate dehydrogenase 1 [IDH1], IDH2, and TET2). Among an expanding panel of mutated genes associated with adverse risk (at least when not coexisting with favorable aber­ rations) are ASXL1, BCOR, EZH2, RUNX1, SF3B1, SRSF2, STAG2, U2AF1, ZRSR2, and TP53. Because prognostic molecular markers in AML are not mutually exclusive and often occur concurrently (>80% patients have at least two or more prognostic gene mutations), distinct marker combinations will certainly be part of continued evolution of AML classification, prognosis, and treatment. Novel drugs that inhibit/modulate cellular pathways activated by genetic aberrations (especially FLT3, IDH1, IDH2, and NPM1/ KMT2A/NUP98) have been remarkably effective in subsets of dis­ ease (see section on treatment of AML). Epigenetic changes (e.g., DNA methylation and/or posttranslational histone modification) and microRNAs are often involved in deregulation of genes involved in hematopoiesis, contribute to leukemogenesis, and may associate with the previously discussed prognostic gene mutations. These changes have been shown to provide biologic insights into leukemogenic mechanisms and provide independent prognostic information. Thera­ peutic progress based on advances in understanding the role of epi­ genetic changes in AML over the last decade has been tremendous. For example, in patients with mutations of IDH1 or IDH2, novel enzymes produced from these respective mutations have aberrant activity and “hijack” the citric acid cycle. These mutations lead to production of a novel “oncometabolite,” 2-hydroxyglutarate, which disrupts a myriad of epigenetic processes. Pharmacologic inhibition of these aberrant enzymes can reverse these leukemogenic activities and restore normal marrow function (though monotherapy is not typically curative). PART 4 Oncology and Hematology In addition to cytogenetic and molecular aberrations, several clini­ cal factors are associated with outcome in AML. Age at diagnosis is the most important. Advancing age is associated with a poor prognosis for two reasons: (1) its influence on the ability to survive induction therapy due to coexisting medical comorbidities, and (2) with each successive decade of age, a greater proportion of patients have intrinsically more resistant disease/adverse genetic risk. Next, a prolonged symptomatic interval with cytopenias preceding AML diagnosis, or a history of antecedent hematologic disorders including myelodysplastic syndrome (MDS) or myeloproliferative neoplasm, is often found in older patients. Preexisting cytopenia is a clinical feature associated with a lower com­ plete remission (CR) rate and shorter survival time. The CR rate is lower in patients who have had anemia, leukopenia, and/or thrombo­ cytopenia for >3 months before the diagnosis of AML when compared to those without such a history. Responsiveness to chemotherapy declines as the duration of the antecedent disorder increases. Likewise, AML-pCT, typically developing after treatment with cytotoxic agents for other malignancies, is often resistant to treatment given its associa­ tion with adverse genetic features. In general, older patients less fre­ quently harbor favorable genetic aberrations (e.g., t[8;21], inv[16], and t[16;16], NPM1 mutation) and more frequently harbor adverse genetic aberrations (e.g., complex karyotypes, mutations in ASXL1, TP53). Other factors independently associated with worse outcome are poor performance status, which influences ability to survive induction therapy, and a high presenting leukocyte count that in some series is an adverse prognostic factor for attaining a CR. Among patients with hyperleukocytosis (>100,000/μL), early central nervous system bleed­ ing and pulmonary leukostasis contribute to poor outcomes. Following administration of therapy, achievement of CR is associ­ ated with better outcome and longer survival, of course. CR is defined after examination of both blood and bone marrow and essentially rep­ resents eradication of detectable leukemia and restoration of normal hematopoiesis. The blood neutrophil count must be ≥1000/μL and the platelet count ≥100,000/μL for formal criteria; CR with incomplete recovery of counts is a lesser but still meaningful response. Hemoglo­ bin concentration is not considered in determining CR. Circulating blasts should be absent. Although rare blasts may be detected in the blood during marrow regeneration, they should disappear on succes­ sive studies. At CR, the bone marrow should contain <5% blasts, and extramedullary leukemia should not be present. ■ ■CLINICAL PRESENTATION Symptoms  Patients with AML usually present with nonspecific symptoms that begin gradually, though sometimes abruptly, and are the consequence of anemia, leukocytosis, leukopenia/leukocyte dys­ function, or thrombocytopenia. Nearly half have symptoms for ≤3 months before the leukemia is diagnosed. Fatigue is a frequent first symptom among AML patients. Anorexia and weight loss are common. Fever with or without an identifiable infection is the initial symptom in ∼10% of patients. Signs of abnor­ mal hemostasis (bleeding, easy bruising) are common. Bone pain, lymphadenopathy, nonspecific cough, headache, or diaphoresis may also occur. Rarely, patients may present with symptoms from a myeloid sar­ coma (a tumor mass consisting of myeloid blasts occurring at anatomic sites other than bone marrow). Sites involved are most commonly the skin, lymph node, gastrointestinal tract, soft tissue, and testis. This may precede or coincide with blood and/or marrow involvement by AML. Patients who present with isolated myeloid sarcoma typically develop blood and/or marrow involvement quickly thereafter and cannot be cured with local therapy (radiation or surgery) alone. Physical Findings  Fever, infection, and hemorrhage are often found at the time of diagnosis; splenomegaly, hepatomegaly, lymph­ adenopathy, and “bone pain” may also be present but less commonly. Hemorrhagic complications are most commonly and, classically, found in APL. APL patients often present with DIC-associated minor hem­ orrhage but may have significant gastrointestinal bleeding, intrapul­ monary hemorrhage, or intracranial hemorrhage. Counterintuitively, thrombosis while less frequent is another well recognized clinical feature of DIC in APL. Complications associated with coagulopathy may also occur in monocytic AML and with extreme degrees of leuko­ cytosis or thrombocytopenia in other morphologic subtypes. Retinal hemorrhages are detected in 15% of patients. Infiltration of the gin­ giva, skin, soft tissues, or meninges with leukemic blasts at diagnosis is characteristic of the monocytic subtypes and those with KMT2A chromosomal abnormalities. Hematologic Findings  Anemia is usually present at diagnosis, although it is not typically severe. The anemia is usually normocytic normochromic. Decreased erythropoiesis in the setting of AML often results in a reduced reticulocyte count, and red blood cell (RBC) sur­ vival is decreased by accelerated destruction. Active blood loss may rarely contribute to the anemia. The median presenting leukocyte count for new AML cases is ∼15,000/μL. Lower presenting leukocyte counts are more typical of older patients and those with antecedent hematologic disorders. Between 25 and 40% of patients have counts <5000/μL, and 20% have counts >100,000/μL. Fewer than 5% have no detectable leukemic cells in the blood. In AML blasts, the cytoplasm often contains primary (nonspecific) granules, and the nucleus shows fine, lacy chromatin with one or more nucleoli characteristic of immature cells. Abnormal rod-shaped granules called Auer rods are not uniformly present, but when they are, AML (and not acute lymphocytic leukemia) is certain (Fig. 109-1). Platelet counts <100,000/μL are found at diagnosis in ∼75% of patients, and ∼25% have counts <25,000/μL. Both morphologic and functional platelet abnormalities can be observed, including large and bizarre shapes with abnormal granulation and inability of platelets to aggregate or adhere normally to one another. Pretreatment Evaluation  Once the diagnosis of AML is suspected, thorough evaluation and initiation of appropriate therapy should follow. In addition to clarifying the subtype of leukemia, initial studies should evaluate the overall functional integrity of the major organ systems, including the cardiovascular, pulmonary, hepatic, and renal systems (Table 109-4). Factors that have prognostic significance, either for achieving CR or for CR duration, should also be assessed before initiat­ ing treatment including cytogenetics and molecular markers. Leukemic A C FIGURE 109-1  Morphology of acute myeloid leukemia (AML) cells. A. Uniform population of primitive myeloblasts with immature chromatin, nucleoli in some cells, and primary cytoplasmic granules. B. Leukemic myeloblast containing an Auer rod. C. Promyelocytic leukemia cells with prominent cytoplasmic primary granules. D. Peroxidase stain shows dark blue color characteristic of peroxidase in granules in AML. cells should be obtained from all consenting patients and cryopreserved for future investigational testing as well as potential use as new diagnos­ tics and therapeutics become available. All patients should be evaluated for infection. Patients with respiratory symptoms should undergo test­ ing for the presence of the novel coronavirus, SARS-CoV-2, and other viruses before initiation of chemotherapy. Most patients are anemic and thrombocytopenic at presentation. Replacement of the appropriate blood components, if necessary, should begin promptly. Because qualitative platelet dysfunction or the pres­ ence of an infection may increase the likelihood of bleeding, evidence of hemorrhage justifies the immediate use of platelet transfusion even if the platelet count is only moderately decreased. About 50% of patients have a mild to moderate elevation of serum uric acid at presentation. Only 10% have marked elevations, but renal precipitation of uric acid and the nephropathy that may result is a seri­ ous but uncommon complication. The initiation of chemotherapy may aggravate hyperuricemia, and patients are usually started immediately on allopurinol and hydration at diagnosis. Rasburicase (recombinant uric oxidase) is also useful for treating uric acid nephropathy and often can normalize the serum uric acid level within hours with a single dose of treatment, although its expense suggests that limiting its use to patients with severe hyperuricemia and/or kidney injury may be prudent (and it should be avoided in setting of glucose-6-phosphate dehydrogenase deficiency). The presence of high concentrations of lysozyme, a marker for monocytic differentiation, may be etiologic in renal tubular dysfunction for a minority of patients. B CHAPTER 109 Acute Myeloid Leukemia D TREATMENT Acute Myeloid Leukemia Treatment of the newly diagnosed patient with AML is usually divided into two phases, induction and postremission management (consolidation) (Fig. 109-2). The initial goal is to induce CR. Once CR is obtained, further therapy must be given to prolong sur­ vival and achieve cure. The initial induction treatment and subse­ quent postremission therapy are chosen based on the patient’s age, overall fitness, and cytogenetic/molecular risk. Intensive therapy with cytarabine and anthracycline in younger patients (<60 years) increases the cure rate of AML. In older patients, the benefit of intensive therapy is controversial in all but favorable-risk patients; novel approaches for selecting patients predicted to be responsive to treatment and new therapies are being pursued. Importantly, even infirm older patients should be considered for therapy; treat­ ment is better than supportive care for all candidates. Improved options have emerged for older AML patients such as the addition of the BCL2 antagonist venetoclax to one of several low-intensity chemotherapies. Venetoclax is currently in testing in combination with intensive chemotherapies as well. Likewise, novel oral drugs targeting IDH1/IDH2, alone (IDH1) or in combination (IDH1 and IDH2) with low-intensity chemotherapy, may be considered as initial therapy for unfit older patients who have mutations in those respective pathways. TABLE 109-4  Initial Diagnostic Evaluation and Management of Adult Patients with AML History Increasing fatigue or decreased exercise tolerance (anemia) Excess bleeding or bleeding from unusual sites (DIC, thrombocytopenia) Fevers or recurrent infections (neutropenia) Headache, vision changes, nonfocal neurologic abnormalities (CNS leukemia or bleed) Early satiety (splenomegaly) Family history of AML (Fanconi, Bloom, or Kostmann syndromes or ataxia-telangiectasia) History of cancer (exposure to alkylating agents, radiation, topoisomerase II inhibitors) Occupational exposures (radiation, benzene, petroleum products, paint, smoking, pesticides) Physical Examination Performance status (prognostic factor) Ecchymosis and oozing from IV sites (DIC, possible acute promyelocytic leukemia) Fever and tachycardia (signs of infection) Papilledema, retinal infiltrates, cranial nerve abnormalities (CNS leukemia) PART 4 Oncology and Hematology Poor dentition, dental abscesses Gum hypertrophy (leukemic infiltration, most common in monocytic leukemia) Skin infiltration or nodules (leukemia infiltration, most common in monocytic leukemia) Lymphadenopathy, splenomegaly, hepatomegaly Back pain, lower extremity weakness (spinal granulocytic sarcoma, most likely in t[8;21] patients) Laboratory and Radiologic Studies CBC with manual differential cell count Chemistry tests (electrolytes, creatinine, BUN, calcium, phosphorus, uric acid, hepatic enzymes, bilirubin, LDH, amylase, lipase) Clotting studies (prothrombin time, partial thromboplastin time, fibrinogen, d-dimer) Viral serologies (CMV, HSV-1, varicella-zoster) RBC type and screen HLA typing for potential allogeneic HCT Bone marrow aspirate and biopsy (morphology, cytogenetics, flow cytometry, molecular studies) Cryopreservation of viable leukemia cells Myocardial function (echocardiogram or MUGA scan) PA and lateral chest radiograph Placement of central venous access device Interventions for Specific Patients Dental evaluation (for those with poor dentition) Lumbar puncture (for those with symptoms of CNS involvement) Screening spine MRI (for patients with back pain, lower extremity weakness, paresthesias) Social work referral for patient and family psychosocial support Counseling for All Patients Provide patients with information regarding their disease and genetic risks, sperm banking or menstrual suppression, financial counseling, support group contact, and consent for tissue banking of leukemic cells Abbreviations: AML, acute myeloid leukemia; BUN, blood urea nitrogen; CBC, complete blood count; CMV, cytomegalovirus; CNS, central nervous system; DIC, disseminated intravascular coagulation; HLA, human leukocyte antigen; HCT, hematopoietic stem cell transplantation; HSV, herpes simplex virus; IV, intravenous; LDH, lactate dehydrogenase; MRI, magnetic resonance imaging; MUGA, multigated acquisition; PA, posteroanterior; RBC, red blood (cell) count. INDUCTION CHEMOTHERAPY The most commonly used induction regimens (for patients other than those with APL) consist of combination chemotherapy with cytarabine and an anthracycline (e.g., daunorubicin, idarubicin). Cytarabine is a cell cycle S-phase–specific antimetabolite that becomes phosphorylated intracellularly to an active triphosphate form that interferes with DNA synthesis. Anthracyclines are DNA intercalators. Their primary mode of action is thought to be inhibi­ tion of topoisomerase II, leading to DNA breaks. In adults, cytarabine used at standard dose (100–200 mg/m2) is administered as a continuous intravenous infusion for 7 days. With cytarabine, anthracycline therapy generally consists of dau­ norubicin (60–90 mg/m2) or idarubicin (12 mg/m2) intravenously on days 1, 2, and 3 (the 7+3 regimen). Other agents can be added (e.g., gemtuzumab ozogamicin) when 60 mg/m2 of daunorubicin is used. Patients failing remission after one induction are offered reinduction with the same (or slightly modified) therapy. The CD33-targeting immunoconjugate gemtuzumab ozogamicin may be added to induction therapy for subsets of patients, especially those with CBF AML. Many alternative intensive approaches other than 7+3 chemotherapy exist and are commonly used. In older patients (age ≥60–65 years), the outcome with conventional intensive therapy is generally poor due to a higher frequency of resistant disease and increased rate of treatment-related morbidity and mortal­ ity. Patients still fare far better with treatment than with supportive care only. Conventional therapy for fit older patients is similar to that for younger patients: the 7+3 regimen with standard-dose cytarabine and idarubicin (12 mg/m2) or daunorubicin (60 mg/m2). For patients aged >65 years, high-dose daunorubicin (90 mg/m2) has increased toxicity and is not recommended. A liposomal preparation of cytarabine and daunorubicin in a fixed molar ratio may instead be administered, especially to fit patients with AML-MR. Patients over 75 years and those unable to receive intensive therapy due to medi­ cal comorbidity may receive repetitive cycles of lower intensity ther­ apy with a hypomethylating agent (HMA; decitabine or azacitidine) or low-dose cytarabine in combination with daily venetoclax (BCL2 antagonist). As noted, targeted IDH1- or IDH2-directed therapy is another consideration for particularly infirm patients. All patients should be considered for clinical trials. With the 7+3 regimen (or other similar approaches), 60–80% of younger and 33–60% of older patients (among those who are candidates for intensive therapy) with primary AML achieve CR. Response rates around 60% in first line have been similarly reported with the combination of HMA plus venetoclax in older or infirm patient groups. Induction death is more frequent with advancing age and medical comorbidity, but the most common reason for treatment failure is lack of remission. Patients with refractory dis­ ease after inductions should be considered for salvage treatments, preferably on clinical trials. Planning for the possibility of alloge­ neic hematopoietic stem cell transplantation (HCT) for all eligible patients under age 75 years is part of optimal initial AML care. Typi­ cally, allogeneic HCT is performed only for patients who are in CR but at risk for relapse, but fit younger patients with primary refrac­ tory disease (not in remission after initial induction) have ∼15–20% cure rates with allogeneic HCT after myeloablative conditioning. For this reason, early planning for possible future allogeneic HCT (including human leukocyte antigen [HLA] typing, donor search, etc.) should be part of the initial approach for most AML patients. POSTREMISSION THERAPY Induction of a durable first CR (CR1) is critical to long-term survival in AML. However, without further therapy, virtually all CR patients will eventually relapse. Thus, postremission therapy is designed to eradicate residual (typically undetectable) leukemic cells to prevent relapse and prolong survival. As with induction, the type of postremission therapy in AML is selected for each indi­ vidual patient based on age, fitness, and cytogenetic/molecular risk. The choice between consolidation with chemotherapy or with transplantation is complex and based on age, risk, and practi­ cal considerations. In younger patients receiving chemotherapy, postremission therapy with intermediate- or high-dose cytarabine for two to four cycles is standard practice. Higher doses of cyta­ rabine during postremission therapy appear more effective than Refractory or relapsed Previously untreateda Favorable-risk Intermediate-risk Either option acceptable Either option acceptable Induction therapy: Daunorubicin+ cytarabine-based regimen Induction therapy: Daunorubicin+ cytarabine-based regimenb,c Investigational therapyb Investigational therapyc If CR, consolidation therapy: Allogeneic HCT (preferred), or IDAC or autologous HCT if age <60d If CR: Investigational therapyd If CR: Investigational therapyd If CR, consolidation therapy: IDACd Refractory (no CR) or relapsed FIGURE 109-2  Algorithm for the therapy of newly diagnosed acute myeloid leukemia (AML). aRisk stratification according to the European LeukemiaNet (see Table 109-3). bYounger patients (<60–65 years) should routinely be offered investigational therapy on a backbone of standard intensive chemotherapy for induction and consolidation. cOlder patients, especially those >65 years or with adverse risk disease, or those who are unfit for intensive anthracycline + cytarabine regimens, may be considered for investigational therapy alone or in combination or lower intensity chemotherapy plus venetoclax. Whether venetoclax-containing regimens will be effective in younger, fit patients when compared to intensive chemotherapy is an important question. dNovel allogeneic transplantation approaches are preferred for nonfavorable risk when available; other investigational therapy or oral azacitidine (approved in nonfavorable risk) as maintenance should be considered following consolidation.     Allogeneic hematopoietic cell transplantation (HCT) is a consideration for all eligible patients in first complete remission (CR) with non–favorable-risk disease and highly recommended for all older patients (60–75 years) and those with adverse risk.     For all forms of AML in fit patients, except acute promyelocytic leukemia (APL), standard induction therapy includes a regimen based on a 7-day continuous infusion of cytarabine (100–200 mg/m2/d) and a 3-day course of daunorubicin (60–90 mg/m2/d) with or without additional drugs. Idarubicin (12 mg/m2/d) can be used in place of daunorubicin (not shown). The value of postremission/consolidation therapy for older patients (>60 years) who do not have favorable-risk disease is uncertain. Patients who achieve CR undergo postremission consolidation therapy, including sequential courses of intermediate-dose cytarabine, allogeneic HCT, autologous HCT, or novel therapies, based on their predicted risk of relapse (i.e., risk-stratified therapy). Patients receiving induction of lower intensity chemotherapy with venetoclax (or investigational therapy) typically receive repetitive cycles of same on an attenuated schedule, if necessary due to myelotoxicity, after achieving remission. Patients with APL (see text for treatment) usually receive tretinoin and arsenic trioxide–based regimens with or without anthracycline-based chemotherapy and possibly maintenance with tretinoin. HLA, human leukocyte antigen; IDAC, intermediate-dose cytarabine. standard doses (such as are used in induction) for those who do not have adverse-risk genetics. Studies have shown that the longstanding practice of high-dose cytarabine (3 g/m2, every 12 h on days 1, 3, and 5) may not improve survival over intermediate-dose cytarabine (IDAC; 1–1.5 g/m2) for such patients. Thus, the ELN has recommended IDAC at 1–1.5 g/m2, every 12 h, on days 1–3, as the optimal postremission chemotherapy approach for favorable- and intermediate-risk younger patients, for two to four cycles. While high-dose cytarabine may not be necessary, it is important to note that younger, favorable-risk patients have worse outcomes when doses <1 g/m2 are used. In contrast to favorable-risk patients, intermediate- or adverse-risk patients should proceed with allogeneic HCT in CR1 when feasible (see transplant discussion below). Because older patients have increased toxicities with higher doses of cytarabine, ELN recommends relatively attenuated cytarabine doses (0.5–1 g/m2, every 12 h, on days 1–3) in favorable-risk older patients. There is no clear value for intensive postremission therapy in non–favorable-risk older patients; allogeneic HCT in CR1 (up to age 75 years) or investigational postremission therapy is recommended. Indeed, postremission therapy is an appropriate setting for introduction of new agents in both older and younger patients. For older patients (with nonfavorable cytogenetic risk) in CR after intensive therapy who have no transplantation option, maintenance treatment with prolonged low-dose oral azacitidine improves survival. Diagnosis AML Salvage treatment Adverse-risk Patient with primary induction failure and candidate for myeloablative allogeneic HCT or CR2 achieved with salvage treatment and has suitable donor available Either option acceptable Induction therapy: Daunorubicin+ cytarabine-based regimenb,c Investigational therapyc Yes: Allogeneic HCT If CR, consolidation therapy: Allogeneic HCT (alternative donor transplant if no HLAmatched donor available)d If CR: Investigational therapyd No: Investigational therapy, autologous HCT considered for favorable-risk patients in CR2 with prolonged CR1 duration (>12 months) CHAPTER 109 Acute Myeloid Leukemia For patients treated initially with lower intensity regimens that include venetoclax, the current practice is to continue repetitive cycles of the same combination of agents after remission until disease progression. Therapy often must be abbreviated over time due to cumulative myelotoxicity. In the largest published trial with azacitidine and venetoclax in older AML, patients had median survival of <15 months; survival depended on genetic risk. The median duration of remission (including those with incomplete count recovery) was 17.5 months. Allogeneic HCT is the best relapse-prevention strategy cur­ rently available for AML. Allogeneic HCT is best understood as an opportunity for immunotherapy; residual leukemia cells potentially elicit an immunologic response from donor immune cells, the socalled graft-versus-leukemia (GVL) effect. The benefit of GVL in relapse risk reduction unfortunately is offset somewhat by increased morbidity and mortality from complications of HCT including graft-versus-host disease (GVHD). Given that relapsed AML is typically resistant to chemotherapy, allogeneic HCT in CR1 (i.e., before relapse ever occurs) is a favored strategy. We have often explained to patients that transplant can effectively “eliminate the needle in a haystack, but not a stack of needles.” Transplant is recom­ mended for patients age <75 years who do not have favorable-risk disease and who have an available HLA-compatible donor (related or unrelated). We recommend allogeneic HCT in CR1 for patients with intermediate-risk disease (Table 109-3). However, consider­ able debate exists regarding whether allogeneic HCT in CR1 is a requirement for younger patients with intermediate-risk AML, as one large series from the Medical Research Council reported that such patients have similar outcomes if transplanted only after relapse (and achievement of CR2), sparing some the long-term morbidity of transplantation. That said, allogeneic HCT is generally recommended as soon as possible after CR1 is achieved unless the patient is in a favorable-risk group. Patients without HLA-matched donors are considered for alternative donor transplants (e.g., HLAmismatched unrelated, haploidentical related, and umbilical cord blood) even in CR1. More effective and safe methods of in vivo T-cell depletion (e.g., posttransplant cyclophosphamide following mismatched transplantation or use of abatacept) have broadened the availability of potential allogeneic HCT donors. Now, virtually any patient with a healthy parent or child has an available donor suitable for allogeneic HCT if desired. Long-term outcomes with conventional chemotherapy for older patients are dismal; trans­ plantation for such patients is expanding and improving outcomes. Trials comparing allogeneic HCT with intensive chemotherapy or autologous HCT have shown improved duration of remission with allogeneic HCT. The relapse risk reduction observed with allogeneic HCT, however, is partially offset by the increase in fatal treatment-related toxicity (GVHD, organ toxicity). Despite this, there is no debate that patients with adverse-risk AML have improved long-term survival with early allogeneic HCT. For rare patients with no allogeneic donor option, high-dose chemotherapy with autologous HCT rescue is another postremission approach in non–adverse-risk subsets. Autologous HCT patients receive their own stem cells (collected during remission and cryopreserved), fol­ lowing administration of myeloablative chemotherapy. The toxicity is relatively low with autologous HCT (5% mortality rate), but the relapse rate is higher than with allogeneic HCT due to the absence of the GVL effect. Favorable- and intermediate-risk patients may benefit from autologous HCT; it is not recommended in adverserisk patients. Practically speaking, autologous HCT in AML patients is less frequently employed currently due to enhanced relapse risk reduction seen with allogeneic HCT and the growing availability of HLA-mismatched donors (and novel transplantation approaches). PART 4 Oncology and Hematology Prognostic factors help to select the appropriate postremission therapy in patients in CR1. Our approach includes allogeneic HCT in CR1 for patients without favorable cytogenetics or genotype. Patients with adverse-risk disease should proceed to allogeneic HCT at CR1 if possible. The decision for allogeneic HCT for younger intermediate-risk patients is complex and individualized as described above; we recommend it. Subsets of patients may benefit from targeted therapy given during remission; emerging data demonstrate survival benefit from incorporation of the FLT3 inhibitors midostaurin or quizartinib, for example, into induction and postremission therapies for patients with FLT3-mutated AML. Allogeneic transplantation in CR1 is still recommended for most of these patients. For patients in morphologic CR, measurement of MRD remains a very important and challenging research area. Cytogenetics are a mainstay of disease assessment, and persistence of abnormal karyotype (despite morphologic CR) is clearly associated with poor clinical outcomes. Immunophenotyping (flow cytometry) to detect minute populations of blasts and/or sensitive molecular assays such as quantitative reverse transcriptase polymerase chain reaction (RT-PCR) to detect AML-associated molecular abnormalities when present (e.g., NPM1, RUNX1/RUNX1T1 and CBFB/MYH11 tran­ scripts, PML/RARA) can be performed to assess MRD at sequential time points during or after treatment. We know that continued detection of MRD after therapy is unfavorable. Whether emerg­ ing next-generation sequencing or serial quantitative assessment using flow or PCR, performed during remission, can effectively direct subsequent therapy and improve clinical outcome remains to be determined for most subtypes. Currently, no consensus exists for the optimal MRD measurement technique or its application, although testing is increasingly employed in clinical practice. Data suggest that MRD measurement can in some settings be a reliable discriminator between patients who will continue in CR or relapse, but whether subsequent therapy (i.e., allogeneic HCT or additional therapy) can effectively eradicate disease in such patients is not yet clear. For patients with NPM1 mutation, MRD-negative status by NPM1 PCR after two courses of chemotherapy predicts favorable outcome without transplantation (even for patients with coexisting FLT3 mutation); emerging data demonstrate that transplantation of MRD-positive patients does indeed improve outcome (rather than just predict they will do poorly irrespective of subsequent therapy given). In the subset of patients with APL, serial PCR (for the PML/ RARA transcript) is a very useful and reliable tool to detect early relapse and to direct initiation of reinduction therapy prior to onset of overt relapse. Critical in the general understanding of MRD in all disease subsets is the recognition that even patients with undetect­ able levels of MRD remain at risk for leukemic relapse. SUPPORTIVE CARE Measures geared to supporting patients through several weeks of neutropenia and thrombocytopenia are critical to successful AML therapy. Patients with AML should be treated in centers expert in providing supportive care. Multi-lumen central venous catheters should be inserted as soon as newly diagnosed AML patients have been stabilized. They should be used thereafter for administration of intravenous medications/chemotherapy and transfusions, as well as for blood drawing instead of venipuncture during prolonged periods of myelosuppression. Adequate and prompt blood bank support is critical to therapy of AML. Platelet transfusions should be given as needed to maintain a platelet count ≥10,000/μL. The platelet count should be kept at higher levels in febrile patients and during episodes of active bleeding or DIC. Patients with poor posttransfusion platelet count increments may benefit from administration of ABO-matched platelets or platelets from HLA-matched donors. RBC transfusions should be considered to keep the hemoglobin level >70–80 g/L (7–8 g/dL) in the absence of active bleeding, DIC, or congestive heart failure, which may require higher hemoglobin levels. Blood products leukodepleted by filtra­ tion should be used to avert or delay alloimmunization as well as febrile reactions. Blood products may also be irradiated to prevent transfusion-associated GVHD. Neutropenia (neutrophils <500/μL or <1000/μL and predicted to decline to <500/μL over the next 48 h) can be part of the initial presentation and/or a side effect of the chemotherapy treatment in AML patients. Thus, infectious complications remain the major cause of morbidity and death during induction and postremission chemotherapy for AML. Antibacterial (e.g., quinolones) and anti­ fungal (e.g., posaconazole) prophylaxis, especially in conjunction with regimens that cause mucositis, is beneficial. For patients who are herpes simplex virus or varicella-zoster seropositive, antiviral prophylaxis should be initiated (e.g., acyclovir, valacyclovir). Fever develops in most patients with AML, but infections are documented in only half of febrile patients. Empiric initiation of empirical broad-spectrum antibacterial and antifungal antibiotics has significantly reduced the number of patients dying of infectious complications (Chap. 79). An antibiotic regimen adequate to treat gram-negative organisms should be instituted at the onset of fever in a neutropenic patient after clinical evaluation, including a detailed physical examination with inspection of the indwelling catheter exit site and a perirectal examination (for perirectal abscess), as well as procurement of cultures and radiographs aimed at docu­ menting the source of fever. Specific antibiotic regimens should be based on institutional antibiotic sensitivity data obtained from where the patient is being treated. Acceptable regimens for empiric antibiotic therapy include monotherapy with imipenem-cilastatin, meropenem, piperacillin/tazobactam, or an extended-spectrum antipseudomonal cephalosporin (cefepime or ceftazidime). The combination of an aminoglycoside with an antipseudomonal peni­ cillin (e.g., piperacillin) or an aminoglycoside in combination with an extended-spectrum antipseudomonal cephalosporin should be considered in complicated or resistant cases. Aminoglycosides should be avoided, if possible, in patients with renal insufficiency. Empirical vancomycin should be added in neutropenic patients with catheter-related infections, blood cultures positive for grampositive bacteria before final identification and susceptibility test­ ing, hypotension or shock, or known colonization with penicillin/ cephalosporin-resistant pneumococci or methicillin-resistant Staphylococcus aureus. In special situations where decreased sus­ ceptibility to vancomycin, vancomycin-resistant organisms, or van­ comycin toxicity is documented, other options including linezolid and daptomycin need to be considered. Caspofungin (or a similar echinocandin), voriconazole, isavu­ conazonium, or liposomal amphotericin B should be considered for antifungal treatment if fever persists for 4–7 days following initiation of empiric antibiotic therapy. Although liposomal for­ mulations of amphotericin B have improved the toxicity profile of this agent, use has been limited to situations with high risk of or documented mold infections, especially in those in whom an azole fails. Caspofungin has been approved for empiric antifungal treat­ ment. Voriconazole has also been shown to be equivalent in efficacy and less toxic than amphotericin B; isavuconazonium may also be effective with fewer drug-drug interactions. Unfortunately, use of prophylactic or empiric antibiotics contributes to the development of resistance and increased incidence of nosocomial infections such as Clostridium difficile colitis, so hospital-wide antibiotic surveil­ lance and isolation strategies should be employed to reduce these complications. Recombinant hematopoietic growth factors have a limited role in AML; myeloid growth factors may be useful in the postremission setting but are not recommended in induction or for “palliative” care for patients not in remission. TREATMENT FOR REFRACTORY OR RELAPSED AML In patients who relapse after achieving CR, the length of first CR is predictive of response to salvage chemotherapy treatment; patients with longer first CR (>12 months) generally relapse with drugsensitive disease and have a higher chance of attaining a CR, even with the same chemotherapeutic agents used for first remission induction. Patients with short prior CR duration are at high risk for treatment failure. Similar to patients with refractory disease, patients with relapsed disease are rarely, if ever, cured by salvage chemotherapy treatments alone. Therefore, patients who eventually achieve a second CR and are eligible for allogeneic HCT should be transplanted. For patients who relapse after allogeneic HCT, no consensus for best therapy exists; outcomes in this setting are very poor. Because achievement of a second CR with routine salvage thera­ pies is relatively uncommon, especially in patients who relapse rapidly after achievement of first CR (<12 months), these patients and those lacking HLA-compatible donors or who are not candidates for alloge­ neic HCT should be considered for innovative approaches on clinical trials. Many new agents are in current testing (Table 109-5). The dis­ covery of novel gene mutations and mechanisms of leukemogenesis that might represent actionable therapeutic targets has prompted the development of many new targeting agents. In addition to kinase inhibitors for FLT3-mutated AML, other compounds target­ ing the aberrant activity of mutant proteins (e.g., IDH1/2 inhibi­ tors) and numerous other biologic mechanisms are either approved by the Food and Drug Administration (FDA) or being tested in clinical trials. Inhibitors of FLT3 (gilteritinib, quizartinib), IDH1 (ivosidenib, olutasidenib), or IDH2 (enasidenib) are approved in AML. Exciting early clinical data with menin inhibitors in AML with KMT2A rearrangement, NPM1 mutation, or other genetic aberrations with shared biology of HOXA cluster gene upregulation are likely to result in FDA approval of the first agent in this pathway during 2024. Furthermore, approaches with antibodies targeting markers commonly expressed on leukemia blasts (e.g., CD33) or leukemia-initiating cells (e.g., CD123) are also under investiga­ tion. Next-generation immune compounds such as bispecific or TABLE 109-5  Novel Therapies in Clinical Development in Acute Myeloid Leukemia (AML) APPROVED BY FOOD AND DRUG ADMINISTRATION SINCE 2017 UNDER INVESTIGATION Kinase inhibitors/ cell signaling FLT3 inhibitors IRAK-4 inhibitors KIT inhibitors PI3K/AKT/mTOR inhibitors Aurora and polo-like kinase inhibitors, CDK4/6 inhibitors, CDK9 inhibitors, CHK1, WEE1, CSFR1, and MPS1 inhibitors SRC and HCK inhibitors Syk inhibitors Midostaurin (FLT3) Gilteritinib (FLT3) Quizartinib (FLT3) Pemigatinib (FGFR1) Epigenetic modulators Menin inhibitors, other spliceosome modulators DNA methyltransferase inhibitors Histone methylation or acetylation modulators Other spliceosome modulators IDH1 and IDH2 inhibitors DOT1L inhibitors BET-bromodomain inhibitors Revumenib (menin inhibitor; FDA review pending, 2024) Enasidenib (IDH2) Ivosidenib (IDH1) Olutasidenib (IDH1) CHAPTER 109 Chemotherapeutic agents Liposomal preparations Nucleoside analogues CPX-351 (liposomal cytarabine and daunorubicin) Oral azacitidine Acute Myeloid Leukemia Mitochondrial inhibitors BH3 mimetics; Bcl-2, Bcl-xL, and Mcl-1 inhibitors Caseinolytic protease inhibitors Venetoclax (BCL2) Therapies targeting oncogenic proteins Fusion transcript targeting EVI1 targeting NPM1 targeting Hedgehog inhibitors Glasdegib (hedgehog) Antibodies and immunotherapies Monoclonal antibodies against CD33, CD44, CD47, CD123, CLEC12A Immunoconjugates Bispecific T-cell engagers (BiTEs) and dual-affinity retargeting molecules (DARTs) for CD33, CD123, others Trispecific T-cell or NK-cell engagers Chimeric antigen receptor (CAR) T cells, genetically engineered T-cell receptor (TCR) T cells, CAR-NK cells Immune checkpoint inhibitors (PD-1/PD-L1, CTLA-4, LAG-3, LILRB4) Vaccines Gemtuzumab ozogamicin (CD33-toxin) Therapies targeting AML environment CXCR4 and CXCL12 antagonists Antiangiogenic therapies Source: Reproduced with permission from H Döhner et al: Diagnosis and management of acute myeloid leukemia in adults: 2017 recommendations from an international expert panel. Blood 129:424, 2017. trispecific antibodies are promising and under study. Investigation of these in combination with other molecular targeting compounds and/or chemotherapy should be pursued. TREATMENT OF ACUTE PROMYELOCYTIC LEUKEMIA APL is a highly curable AML subtype, and ∼85% of these patients achieve long-term survival with current approaches. APL has long been shown to be responsive to cytarabine and daunorubicin. However, in the past, patients who were treated with these drugs # 40 - 110 Chronic Myeloid Leukemia ### 110 Chronic Myeloid Leukemia alone frequently died from DIC induced by the release of gran­ ule components by the chemotherapy-treated leukemia cells. The prognosis of APL patients changed dramatically first with the introduction of tretinoin (all-trans-retinoic acid [ATRA]) and then with combined ATRA and arsenic trioxide (ATO). ATRA is an oral drug that induces the differentiation of leukemic cells bearing the t(15;17), which disrupts the RARA gene encoding retinoid acid receptor. ATRA decreases the frequency of DIC but often produces another complication called the APL (differentiation) syndrome. Occurring within the first 3 weeks of treatment, it is characterized by fever, fluid retention, dyspnea, chest pain, pulmonary infiltrates, pleural and pericardial effusions, and hypoxemia. The syndrome is related to adhesion of differentiated neoplastic cells to the pul­ monary vasculature endothelium. Glucocorticoids, chemotherapy for cytoreduction, and/or supportive measures can be effective for management of the APL syndrome. Temporary discontinuation of ATRA is necessary in cases of severe APL syndrome (i.e., patients developing renal failure or requiring admission to the intensive care unit due to respiratory distress). The mortality rate of this syndrome is ∼10% if unrecognized. APL syndrome may also occur, less commonly, with ATO. In adults with low-risk APL (low leukocyte count at presenta­ tion), ATRA (45 mg/m2/d) plus ATO (0.15 mg/kg/d) was compared to ATRA plus concurrent idarubicin chemotherapy. ATRA/ATO was superior and is the new standard of care for such patients. CR rates in low-risk disease approach 100%, with excellent long-term survival. Notably, patients with high-risk APL (defined as leukocyte count >10,000/μL) must be uniquely treated, as they require imme­ diate cytoreduction with chemotherapy due to life-threatening APL syndrome and rapidly rising leukocyte count after initiation of ATRA. High-risk patients are at increased risk for induction death due to this syndrome as well as increased frequency of hemorrhagic complications (related to DIC). PART 4 Oncology and Hematology Assessment of residual disease by PCR amplification of the t(15;17) chimeric gene product PML-RARA following the final cycle of treatment is important. Disappearance of the signal is associated with long-term disease-free survival; its persistence or reemergence invariably predicts relapse. Sequential monitoring by PCR for PML-RARA is now considered standard for postremission monitoring of APL, at least in high-risk patients. ■ ■FURTHER READING Dinardo CD et al: Venetoclax combined with decitabine or azacitidine in treatment-naive, elderly patients with acute myeloid leukemia. Blood 133:7, 2019. Döhner H et al: Diagnosis and management of AML in adults: 2022 recommendations from an international expert panel on behalf of the ELN. Blood 140:1345, 2020. Issa GC et al: The menin inhibitor revumenib in KMT2A-rearranged or NPM1-mutant leukaemia. Nature 615: 920, 2023. Jaiswal S, Ebert BL: Clonal hematopoiesis in human aging and dis­ ease. Science 366:eaan4673, 2019. Jongen-Lavrenic M et al: Molecular minimal residual disease in acute myeloid leukemia. N Engl J Med 378:1189, 2018. Khoury JD et al: The 5th edition of the World Health Organization Clas­ sification of Haematolymphoid Tumours: Myeloid and histiocytic/ dendritic neoplasms. Leukemia. 36:1703, 2022. Perl AE et al: Gilteritinib or chemotherapy for relapsed or refractory FLT3-mutated AML. N Engl J Med 381:1728, 2019. Pollyea DA et al: Enasidenib, an inhibitor of mutant IDH2 proteins, induces durable remissions in older patients with newly diagnosed acute myeloid leukemia. Leukemia 33:2575, 2019. Roboz GJ et al: Ivosidenib induces deep durable remissions in patients with newly diagnosed IDH1-mutant acute myeloid leukemia. Blood 135:463, 2020. Stone RM et al: Midostaurin plus chemotherapy for acute myeloid leukemia with a FLT3 mutation. N Engl J Med 377:454, 2017. Hagop Kantarjian, Elias Jabbour Chronic Myeloid Leukemia Chronic myeloid leukemia (CML) is a clonal hematopoietic myelopro­ liferative stem cell neoplasm. The disease is driven by the BCR::ABL1 chimeric gene that codes for a constitutively active tyrosine kinase, resulting from a reciprocal balanced translocation between the long arms of chromosomes 9 and 22, t(9;22)(q34.1;q11.2), known as the Philadelphia chromosome (Ph) (Fig. 110-1). Untreated, the course of CML is typically biphasic or triphasic, with an early indolent or chronic phase, followed often by an accelerated phase and a terminal blastic phase. Before the era of BCR::ABL1 tyrosine kinase inhibitors (TKIs), the median survival in CML was 3–7 years, and the 10-year survival rate was 30% or less. Introduced into standard CML therapy in 2000, TKIs have revolutionized the treatment, natural history, and progno­ sis of CML. Today, the estimated 10-year survival rate with imatinib mesylate, the first BCR::ABL1 TKI approved, is >85% and approaches that of a normal age-matched population. Allogeneic hematopoietic stem cell transplantation (HSCT), a curative approach but one that involves more risks, is now offered as later-line therapy after failure of TKIs. ■ ■INCIDENCE AND EPIDEMIOLOGY CML accounts for ∼15% of all cases of leukemia. There is a slight male predominance (male-to-female ratio 1.6:1). The median age at diag­ nosis is 55–65 years. It is uncommon in children; only 3% of patients with CML are younger than 20 years, although in recent years, a higher proportion of young patients have been diagnosed. The incidence of CML increases gradually with age, with a steeper increase after the age of 40–50 years. The annual incidence of CML is 2 cases per 100,000 individuals. In the United States, this translates into about 9000 new cases per year. The incidence of CML has not changed over several decades. By extrapolation, the worldwide annual incidence of CML is about 250,000 cases. With a median survival of 3–6 years before 2000, the disease prevalence in the United States was ~30,000 cases. With TKI therapy, the annual mortality has been reduced from 10–20% to about 1–2%. Therefore, the prevalence of CML is expected to continue to increase. Based on these estimates (incidence of 9000 cases, annual mortality of 2%), the plateau prevalence of CML is estimated to be reached at ~450,000 in the United Stated (9000 × 100/2) by about 2040, with full TKI optimal treatment penetration. The worldwide prevalence will depend on the treatment penetration of TKIs and their effect on reduction of worldwide annual mortality. Ideally, with full TKI treatment penetration, the worldwide prevalence should plateau at 35 times the incidence, or ~9–10 million patients. These estimates are based on extrapolations from the incidence and prevalence of CML in the United States, as well as an estimated annual mortality of 2% with modern TKI therapy; they could vary considerably if the estimates were to change. ■ ■ETIOLOGY There are no familial associations in CML. The risk of developing CML is not increased in monozygotic twins or in relatives of patients with CML. No etiologic agents are incriminated, and no associations exist with exposures to benzene or other toxins, fertilizers, insecticides, or viruses. CML is not a frequent secondary leukemia following therapy of other cancers with alkylating agents and/or radiation. Exposure to ionizing radiation (e.g., nuclear accidents, higher doses of radiation treatment) has increased the risk of CML, which peaks at 5–10 years after exposure and is dose-related. The median time to development of CML among atomic bomb survivors was 6.3 years. Following the Chernobyl accident, no increase in the incidence of CML was reported, suggesting that larger dose exposures of radiation are required to cause CML. Because of adequate protection, the risk of CML has not q34 t(9;22)(q34.1;q11.2) A Chromosomes Minor BCR BCR Major BCR ABL1 Micro BCR Normal ABL1 Breakpoint Translocation (9;22) B FIGURE 110-1  A. The Philadelphia (Ph) chromosome cytogenetic abnormality. B. Breakpoints in the long arms of chromosome 9 (ABL1 locus) and chromosome 22 (BCR regions) result in at least three different BCR::ABL1 oncoprotein messages, p210BCR::ABL1 (most common message in chronic myeloid leukemia [CML]), p190BCR::ABL1 (present in two-thirds of patients with Ph-positive acute lymphoblastic leukemia; rare in CML), and p230BCR::ABL1 (rare in CML and associated with an indolent course). Other rearrangements (e.g., e14a3, e14a3) are less common. (© 2013 The University of Texas MD Anderson Cancer Center.) increased among individuals working in the nuclear industry or among radiologists. ■ ■PATHOPHYSIOLOGY The t(9;22)(q34.1;q11.2) is present in >90% of classical CML cases. It results from a balanced reciprocal translocation between the long arms of chromosomes 9 and 22. It is present in hematopoietic cells (myeloid, erythroid, megakaryocytes, and monocytes; less often mature B lym­ phocytes; rarely mature T lymphocytes, but not stromal cells), but not in other cells in the human body. As a result of the genetic transloca­ tion, DNA sequences from the cellular ABL proto-oncogene 1 (ABL1) are juxtaposed to the major breakpoint cluster region (BCR) gene on chromosome 22, generating a hybrid BCR::ABL1 oncogene. Depending on the breakpoint site in the major BCR region on chromosome 22 (e13 or e14), two main messenger RNA transcripts occur, e13a2 (previously b2a2) and e14a2 (previously b3a2). Both transcripts encode for a novel oncoprotein of molecular weight 210 kDa, referred to as p210BCR::ABL1 (Fig. 110-1B). This oncoprotein exhibits constitutive kinase activity that leads to increased proliferation and reduced apoptosis of CML cells, endowing them with a growth advantage over their normal coun­ terparts. Over time, normal hematopoiesis is suppressed, but normal stem cells can persist and reemerge following effective anti-CML ther­ apy, for example with TKIs. In two-thirds of patients with Ph-positive q11.2 5' e1 e1' e2' e12 e13 e14 e15 e16 CHAPTER 110 5' e19 1b Chronic Myeloid Leukemia 1a a2 a3 3' e1a2 e13a2 e14a2 e19a2 a11 p210BCR-ABL1 p230BCR-ABL1 p190BCR-ABL1 3' acute lymphoblastic leukemia (ALL) and in rare cases of CML, the breakpoint in BCR is more centromeric, in a region called the minor BCR region (mBCR). As a result, a shorter sequence of BCR is fused to ABL1, with a consequent e1a2 transcript and a smaller BCR::ABL1 oncoprotein, p190BCR::ABL1. When occurring in Ph-positive CML, this translocation is associated with a worse outcome. A rarer breakpoint in BCR occurs telomeric to the major BCR region in the micro-BCR (μ-BCR) region. It juxtaposes a larger fragment of the BCR gene to ABL1 and produces an e19a2 transcript and a larger p230BCR::ABL1 onco­ protein (associated with a more indolent CML course). Other rear­ rangements (based on different breakpoints in the ABL region), such as e13a3 or e14a3 (also resulting in a p210BCR::ABL1 oncoprotein), occur much less frequently. These are not readily identifiable nor quantifi­ able with the routine polymerase chain reaction (PCR) probes, thus producing falsely negative PCR levels on follow-up studies if not tested at diagnosis. The constitutive activation of BCR::ABL1 results in autophosphory­ lation and activation of multiple downstream pathways that affect gene transcription, apoptosis, stromal adherence, skeletal organization, and degradation of inhibitory proteins. These transduction pathways involve RAS, mitogen-activated protein (MAP) kinases, signal trans­ ducers and activators of transcription (STAT), phosphatidylinositol3-kinase (PI3k), MYC, and others. These interactions are mostly mediated through tyrosine phosphorylation and require binding of BCR::ABL1 to adapter proteins such as GRB-2, CRK, CRK-like (CRK-L) protein, and Src homology containing proteins (SHC). Most BCR::ABL1 TKIs (imatinib, dasatinib, bosutinib, nilotinib, ponatinib) bind to the BCR::ABL1 ATP-binding domain, inhibiting its kinase activity, preventing the activation of transformation pathways, and inhibiting downstream signaling. As a result, proliferation of CML cells is inhibited and apoptosis induced, allowing the reemergence of nor­ mal hematopoiesis. An additional layer of complexity in CML is related to differences in signal transduction between CML-differentiated cells and early progenitors. Beta-catenin, Wnt1, Foxo3a, transforming growth factor β, interleukin 6, PP2A, SIRT1, and others have been implicated in CML stem cell survival. ABL1 also has a myristoyl site that functions as a negative regulator of its kinase activity. This site and its negative regulatory activity are lost upon fusion with BCR. Asciminib, a novel “third-generation” TKI (third generation refers to novel TKIs that inhibit the ABL1-T315I-mutated CML disease, such as ponatinib), is the first-in-class TKI that works through a novel mecha­ nism that specifically targets the ABL1 myristoyl pocket (STAMP is an acronym for specifically targets the ABL1 myristoyl pocket). Asciminib binds this myristoyl site and restores the lost inhibitory activity. Muta­ tions in other cancer-associated genes may also occur at diagnosis, most frequently in ASXL1, IKZF1, and RUNX1. Their significance is being clarified. Some reports suggest that their presence may be associated with worse response to TKI therapy and a higher risk of transforma­ tion to blastic phase. An ASXL1 mutation is often associated with a higher incidence of recurrent cytopenias on TKI therapy, resulting in frequent treatment interruptions, TKI dose reductions, failure to achieve optimal therapeutic milestones, and the need to proceed to allogeneic HSCT. PART 4 Oncology and Hematology Experimental models have established the causal relationship between the BCR::ABL1 rearrangement and the development of CML. In animal models, expression of BCR::ABL1 in normal hema­ topoietic cells produced CML-like disorders or lymphoid leukemia, demonstrating the leukemogenic potential of BCR::ABL1 as a single oncogenic abnormality. Other models, however, suggest the need for a “second hit.” The cause of the BCR::ABL1 rearrangement is unknown. Molecular techniques that detect BCR::ABL1 at a level of 1 in 108 cells identify this molecular abnormality in the blood of up to 25% of normal adults and 5% of infants, but 0% of cord blood samples. This suggests that BCR::ABL1 is not sufficient to cause overt CML in the overwhelming majority of individuals in whom it occurs. Because CML develops in only 2 of 100,000 individuals annually, additional molecular events or poor immune recognition of the rearranged cells may contribute to overt CML. CML is defined by the presence of the BCR::ABL1 fusion gene in a patient with a myeloproliferative neoplasm. In some patients with a typical morphologic picture of CML, the Ph chromosome is not detectable by standard G-banding karyotype, but fluorescence in situ hybridization (FISH) and/or molecular studies (PCR) detect BCR::ABL1. These patients have a course similar to patients with Phpositive CML and respond to TKI therapy. Many of the remaining patients have atypical morphologic or clinical features and have other diseases, such as atypical CML, chronic myelomonocytic leukemia, and myelodysplastic syndrome/myeloproliferative neoplasms (MDS/ MPN). These individuals do not respond to TKI therapy and usually have a poor prognosis with a median survival of ~2–3 years. Detection of mutations in the granulocyte colony-stimulating factor receptor (CSF3R) in chronic neutrophilic leukemia (80% of cases) and in some cases of atypical CML (5–10% of cases), mutations in SETBP1 in atypi­ cal CML (25% of cases), and mutations in SF3B1 in MDS/MPN with ringed sideroblasts and marked thrombocytosis (MDS/MPN-RS-T; 50–70% of cases, associated with longer median survival of 7 years vs 3.3 years with wild-type SF3B1) supports the notion that these are distinct molecular and biologic entities. Patients with chronic neu­ trophilic leukemia or atypical CML whose disease is associated with CSF3R mutation may respond to ruxolitinib (a JAK2 inhibitor) therapy (complete response rate 50–60%). The events associated with the transition of CML from a chronic to the accelerated-blastic phase are poorly understood. Characteristic chromosomal abnormalities such as a double Ph, trisomy 8, isochro­ mosome 17 or deletion of 17p (loss of TP53), 20q–, translocations involving 3q26, and others may be noted with disease acceleration. Molecular events associated with transformation include mutations in TP53, retinoblastoma 1 (RB1), myeloid transcriptions factors like RUNX1, and cell cycle regulators like p16. A plethora of other muta­ tions or functional abnormalities have been implicated in blastic trans­ formation, but no unifying theme has emerged other than the fact that BCR::ABL1 itself induces genetic instability that favors the acquisition of additional molecular defects and eventually results in blastic trans­ formation. One critical effect of TKIs is to stabilize the CML genome, leading to a reduced transformation rate. In particular, the previously observed sudden blastic transformations (i.e., abrupt transformation to blastic phase in a patient who had been in cytogenetic response) have become uncommon, occurring rarely in younger patients in the first 1–2 years of TKI therapy (usually sudden lymphoid blastic transfor­ mation). Sudden blastic transformations beyond the third year of TKI therapy are rare in patients who continue on TKI therapy. The inci­ dence of any CML blastic transformation is now reduced to 5–6% at 10 years. Moreover, the course of CML is now frequently more indolent in patients treated with TKI, even without cytogenetic response, com­ pared to previous experience with hydroxyurea/busulfan, suggesting a definite clinical benefit of continued inhibition of the kinase activity. Among patients developing resistance to TKIs, several resistance mechanisms have been observed. The most clinically relevant one is the development of ABL1 kinase domain mutations that may prevent the binding of TKIs to the catalytic site (ATP-binding site) of the kinase or maintain the kinase activity despite the presence of a TKI. More than 100 ABL1 kinase domain mutations have now been described, many of which confer relative or absolute resistance to imatinib. Consequently, secondgeneration (i.e., dasatinib, nilotinib, bosutinib) and third-generation TKIs (ponatinib, asciminib, olverembatinib [approved in China; ongoing trials worldwide since 2023]) were developed. All three third-generation TKIs demonstrate significant efficacy against T315I, a “gatekeeper” mutation that prevents binding of, and causes resistance to, imatinib and the second-generation TKIs (dasatinib, bosutinib, nilotinib). ■ ■CLINICAL PRESENTATION The presenting signs and symptoms in CML depend on the availabil­ ity of and access to health care, including physical examinations and screening tests. In developed countries, because of the wider access to health care screening and physical examinations, 50–60% of patients are diagnosed on routine blood tests and have minimal symptoms at presentation, such as fatigue. In geographic locations where access to health care is more limited, patients often present with high CML disease burden including splenomegaly, anemia, and related symptoms (abdominal pain, weight loss, fatigue), associated with a higher fre­ quency of high-risk CML. Presenting findings in patients diagnosed in the United States are shown in Table 110-1. Symptoms  Most patients with CML (90%) present in the indolent or chronic phase. Depending on the timing of diagnosis, patients are often asymptomatic (if the diagnosis is discovered during health care screening tests). Common symptoms, when present, are manifestations of anemia and splenomegaly. These include fatigue, malaise, weight loss (if high leukemia burden), or early satiety and left upper quadrant pain or masses (from splenomegaly). Less common presenting find­ ings include thrombotic or hyperviscosity-related events from severe leukocytosis or thrombocytosis. These include priapism, cardiovas­ cular complications, myocardial infarction, venous thrombosis, visual disturbances, dyspnea and pulmonary insufficiency, drowsiness, loss of coordination, confusion, or cerebrovascular accidents. Manifestations of bleeding diatheses include retinal hemorrhages, gastrointestinal bleeding, and others. Patients who present with, or progress to, the accelerated or blastic phases frequently have additional symptoms including unexplained fever, significant weight loss, severe fatigue, bone and joint pain, bleeding and thrombotic events, and infections. TABLE 110-1  Presenting Signs and Symptoms of Newly Diagnosed Philadelphia Chromosome–Positive Chronic Myeloid Leukemia in Chronic Phase PARAMETER PERCENTAGE Age ≥60 years (median) 40–50 (55–65) Female gender 35–45 Splenomegaly Hepatomegaly 5–10 Lymphadenopathy Other extramedullary disease Hemoglobin <10 g/dL 10–15 Platelets     >450 × 109 cells/L 30–35   <100 × 109 cells/L 3–5 White blood cells ≥50 × 109 cells/L 35–40 Marrow     ≥5% blasts   ≥5% basophils 10–15 Peripheral blood     ≥3% blasts 8–10   ≥7% basophils Additional chromosomal abnormalities (other than the Philadelphia chromosome) 4–5 Sokal risk     Low 60–65   Intermediate 25–30   High Physical Findings  Splenomegaly is the most common physical finding, occurring in 20–70% of patients depending on health care screening frequency. Less common findings include hepatomegaly (5–10%), lymphadenopathy (5%), and extramedullary disease (skin or subcutaneous lesions). The latter indicates CML transformation if a biopsy confirms predominance of blasts. Other physical findings are manifestations of complications of high tumor burden described earlier (e.g., cardiovascular, cerebrovascular, bleeding). High basophil counts may be associated with histamine overproduction causing pru­ ritus, diarrhea, flushing, and even gastrointestinal ulcers. Hematologic and Marrow Findings  In untreated CML, leuko­ cytosis ranging from 10–500 × 109/L is common. The peripheral blood differential shows left-shifted hematopoiesis with predominance of neutrophils and the presence of bands, myelocytes, metamyelocytes, promyelocytes, and blasts (usually ≤5%). Basophils and/or eosinophils are frequently increased. Thrombocytosis is common, but thrombocy­ topenia is rare and, when present, suggests a worse prognosis, disease acceleration, or an unrelated etiology. Anemia is present in one-third of patients. Cyclic oscillations of counts are noted in 10–20% of patients without treatment. Biochemical abnormalities include a low leukocyte alkaline phosphatase score and high levels of vitamin B12, uric acid, lactic dehydrogenase, and lysozyme. The presence of unexplained and sustained leukocytosis, with or without splenomegaly, should lead to a marrow examination and cytogenetic analysis. The bone marrow is hypercellular with marked myeloid hyperpla­ sia and a high myeloid-to-erythroid ratio of 15–20:1. Marrow blasts are typically 5% or less; when higher, they carry a worse prognosis or represent transformation to accelerated phase (if they are ≥15%). Increased reticulin fibrosis (detected with silver stain) is common, with 30–40% of patients demonstrating grade 3–4 reticulin fibrosis. This was considered adverse in the pre-TKI era. With TKI therapy, reticulin fibrosis resolves in most patients and is not an indicator of poor prog­ nosis. Collagen fibrosis (Wright-Giemsa stain) is rare at diagnosis. Dis­ ease progression with a “spent phase” of myelofibrosis (myelophthisis, or burnt-out marrow) was a common end-stage CML condition with busulfan therapy (20–30%); it is extremely rare now with TKI therapy. Cytogenetic and Molecular Findings  The diagnosis of CML is straightforward and depends on documenting the translocation t(9;22) (q34.1;q11.2), which is identified by G-banding in 90% of cases. This is known as the Philadelphia chromosome (initially identified in Philadel­ phia as a minute chromosome; later identified to be chromosome 22) (Fig. 110-1). Some patients (~10%) may have complex translocations (complex variant Ph) involving three or more chromosomes including chromosomes 9 and 22 and one or more additional chromosomes. Others may have a “masked Ph,” involving translocations between chromosome 9 and a chromosome other than 22 (but molecularly showing the ABL1 rearrangement; known as simple variant Ph). The prognosis of these patients and their response to TKI therapy are like those in patients with Ph. Translocation (9;22)(q34;p13)/ETV6::ABL1 is now classified as a myeloproliferative neoplasm-eosinophilia and may respond better to second-generation TKIs. About 5–10% of patients may have additional chromosomal abnormalities (ACAs) in the Ph-positive cells at diagnosis. These usually involve trisomy 8, a double Ph, isochromosome 17 or 17p deletion, 20q–, or others. This was historically a sign of adverse prognosis, particularly when trisomy 8, double Ph, or chromosome 17 abnormalities were noted. A less com­ mon abnormality involving chromosome 3q26.2 occurs with disease progression and carries a poor prognosis. CHAPTER 110 Techniques such as FISH and PCR are now used to aid in the diag­ nosis of CML. They are more sensitive to estimate the CML burden in patients on TKI therapy. They can be done on peripheral blood and thus are more convenient to patients. Patients with CML at diagnosis should have a FISH analysis to quantify the percentage of Ph-positive cells, if FISH is used to replace marrow cytogenetic analysis in moni­ toring response to therapy. FISH will not detect additional chromo­ somal abnormalities; thus, a cytogenetic analysis is recommended at the time of diagnosis. In addition, 10–15% of patients may develop chromosomal abnormalities in Ph-negative metaphases after respond­ ing to TKIs. These abnormalities may carry a worse prognosis but are not detected by FISH unless already identified and FISH is used to follow them. Molecular studies at diagnosis are important to docu­ ment the type and presence of BCR::ABL1 transcripts to avoid spurious “undetectable” BCR::ABL1 transcripts on follow-up studies, with the false impression of a complete molecular response. The presence of the Philadelphia chromosome with “negative” PCR with standard method­ ology should prompt investigation of atypical transcripts (e13a3, e14a3, e19a2, others). Chronic Myeloid Leukemia Both FISH and PCR studies can be falsely positive at low levels or falsely negative because of technical issues. Therefore, a diagnosis of CML must always rely on a marrow analysis with routine cytogenetics. The diagnostic bone marrow confirms the presence of the Ph chromo­ some, detects additional chromosomal abnormalities, and quantifies the percentage of marrow blasts and basophils. In 10% of patients, the percentage of marrow blasts and basophils can be significantly higher than in the peripheral blood, conferring poorer prognosis or even rep­ resenting disease transformation. Monitoring patients on TKI therapy by cytogenetics, FISH, and PCR has become an important standard practice to assess response to therapy, emphasize compliance, evaluate possible treatment resistance, identify the need to change TKI therapy, and determine the need to assess for kinase domain mutations. Because of the decreasing reliance of bone marrow aspirations to monitor response, equivalence has been established to correlate cytogenetic results with PCR values. These are not absolute correlations but provide adequate guidance. A partial cytogenetic response is defined as the presence of 35% or less Ph- positive metaphases by routine cytogenetic analysis. This is roughly equivalent to BCR::ABL1 transcripts on the International Scale (IS) of 10% or less. A complete cytogenetic response refers to the absence of Ph-positive metaphases (0% Ph positivity). This is approximately equiv­ alent to BCR::ABL1 transcripts (IS) ≤1% (MR2). A major molecular response (MMR or MR3) refers to BCR::ABL1 transcripts (IS) ≤0.1%, or roughly a 3-log or greater reduction of BCR::ABL1 transcripts from a standardized baseline. MR4 (deep molecular response; DMR) refers to BCR::ABL1 transcripts (IS) ≤0.01%, and MR4.5 refers to BCR::ABL1 transcripts (IS) ≤0.0032%, roughly equivalent to a 4.5-log reduction or greater of transcripts. Findings in CML Transformation  Progression of CML is usu­ ally associated with leukocytosis resistant to therapy, increasing anemia, fever and constitutional symptoms, and increased blasts and basophils in the peripheral blood or marrow. Criteria of acceleratedphase CML, historically associated with median survival of <2 years, include the presence of 15% or more peripheral blasts, 30% or more peripheral blasts plus promyelocytes, 20% or more peripheral baso­ phils, cytogenetic clonal evolution (presence of additional chromo­ somal abnormalities other than Ph), and thrombocytopenia <100 × 109/L (unrelated to therapy). About 5–10% of patients present with de novo accelerated phase or blastic phase. The prognosis of de novo accelerated phase with TKI therapy has improved, with an estimated 8-year survival rate of 60–70%. The median survival of accelerated phase evolving from chronic phase has also improved from a histori­ cal median survival of 18 months to an estimated 3-year survival rate of 50% on TKI therapy. Therefore, the criteria for accelerated-phase CML should be revisited because most clinical criteria defining accel­ erated phase have lost much of their prognostic significance. The newest World Health Organization (WHO) classification suggested eliminating accelerated-phase CML as an entity and classifying such patients as high-risk CML. However, the survival of patients with both de novo and evolved accelerated-phase CML is significantly worse than in high-risk CML. The accelerated-phase definition should be maintained in order to recognize such patients and treat them differ­ ently than chronic-phase CML, either with existing standards of care (combinations of TKIs with other agents, allogeneic HSCT) or on investigational trials of novel TKIs or other modalities. Blastic-phase CML is defined by the presence of 30% or more peripheral or mar­ row blasts or the presence of sheets of blasts in extramedullary disease (usually skin, soft tissues, or lytic bone lesions). Blastic-phase CML is commonly myeloid (60%) but can present uncommonly as erythroid, promyelocytic, monocytic, or megakaryocytic. Lymphoid blastic phase occurs in about 25% of patients. Lymphoblasts are terminal deoxy­ nucleotide transferase positive and peroxidase negative (although occasionally with low positivity up to 3–5%) and express lymphoid markers (CD10, CD19, CD20, CD22). They also often express myeloid markers (50–80%), resulting in diagnostic challenges. Proper immu­ nophenotypic diagnosis is important because lymphoid blastic-phase CML is responsive to anti-ALL-type chemotherapy (e.g., hyper-CVAD [cyclophosphamide, vincristine, doxorubicin, and dexamethasone]) in combination with TKIs and immunotherapies (complete response rate 70%; median survival 3 years; high rates of bridging to allogeneic HSCT and possible cure). PART 4 Oncology and Hematology ■ ■PROGNOSIS AND CML COURSE Before the TKI era, the annual mortality in CML was 10% in the first 2 years and 15–20% thereafter. The median survival in CML was 3–7 years (with hydroxyurea-busulfan and interferon α). With­ out a curative option of allogeneic HSCT, the course of CML was toward transformation to, and death from, accelerated or blastic phases for most patients. Even disease stability was unpredictable, with some patients demonstrating sudden transformation to a blastic phase. With imatinib therapy, the annual mortality rate in CML has decreased to 1–2% in the first 20 years of observation. The 10-year survival rate is about 85%, the 10-year CML-specific survival rate is 90%, and CML-specific mortality rate is 10%; the 10-year incidence of blastic transformation is 5–6%. More than half of the deaths are from conditions other than CML, such as old age, comorbidities, accidents, suicides, other cancers, and other medical conditions (e.g., infections, surgical procedures) (Fig. 110-2). The course of CML has also become quite predictable. In the first 2 years of TKI therapy, rare sudden transformations are still reported (1–2%), usually lymphoid blastic transformations that respond to combinations of chemother­ apy and TKIs followed by allogeneic HSCT. These may be explained by the intrinsic mechanisms of sudden transformation already exist­ ing in the CML clones before the start of therapy that were not ame­ nable to TKI inhibition, in particular imatinib. Second-generation TKIs (nilotinib, dasatinib, bosutinib) used as frontline therapy have reduced the incidence of transformation in the first 2–3 years from 4–6% with imatinib to 1–2% with second-generation TKIs. Disease transformation to accelerated or blastic phase is rare with continued TKI therapy, estimated at <1% annually in years 4–10 of follow-up. Patients usually develop resistance in the form of cytogenetic relapse, followed by hematologic relapse and subsequent transformation, rather than the previously feared sudden transformation without the warning signals of cytogenetic-hematologic relapse. Before the imatinib era, several pretreatment prognostic factors predicted for worse outcome in CML and have been incorporated into prognostic models and staging systems. These have included older age, significant splenomegaly, anemia, thrombocytopenia or thrombocyto­ sis, high percentages of blasts and basophils (and/or eosinophils), mar­ row fibrosis, additional chromosomal abnormalities, and others. The introduction of TKIs into CML therapy has decreased or eliminated the prognostic impact of these prognostic factors and the significance of the CML models (e.g., Sokal, Hasford, European Treatment and Outcome Study [EUTOS]). Treatment-related prognostic factors have emerged as the most important prognostic factors in the era of ima­ tinib therapy. Achievement of complete cytogenetic response (MR2) has become the major therapeutic endpoint and is the only endpoint associated with improvement in survival. Achievement of MMR (MR3) is associated with decreased risk of events (relapse) and CML transformation but not with survival prolongation among patients with complete cytogenetic response. This may be due to the efficacy of salvage TKI therapies, which are implemented at the first evidence of cytogenetic relapse. Achievement of durable DMR (MR4/MR4.5) may offer the possibility of treatment-free remission (TFR). A durable DMR for 2+ years is associated with a TFR rate of 50%; a durable DMR for 5+ years is associated with a TFR rate of 80%+. A TFR may allow a temporary TKI therapy interruption in women pursuing pregnancy. The lack of achievement of MMR or DMR should not be considered as “failure” of a particular TKI therapy and/or an indication to change the TKI or to consider allogeneic HSCT. Long-term updates of randomized trials suggest that second- generation TKIs and imatinib are similarly effective in lower-risk CML; second-generation TKIs may offer a therapeutic advantage in high-risk CML and when TFR is an important treatment endpoint (younger patients). TREATMENT Chronic Phase Chronic Myeloid Leukemia Since 2001, six oral BCR::ABL1 TKIs have been approved by the U.S. Food and Drug Administration (FDA) for the treat­ ment of CML. These include imatinib (Gleevec, Glivec), nilotinib (Tasigna), dasatinib (Sprycel), bosutinib (Bosulif), ponatinib (Iclu­ sig), and asciminib (Scemblix). Dasatinib, nilotinib, and bosutinib are referred to as second-generation TKIs; ponatinib and asciminib are referred to as third-generation TKIs, a term also used generally for the more recently developed TKIs that are active against T315Imutated CML (asciminib is also referred to as a STAMP inhibitor because of its different mechanism of action). Nilotinib is similar in structure to imatinib but 30 times more potent. Dasatinib and bosutinib inhibit the SRC family of kinases in addition to ABL1, with dasatinib reported to be 300 times more potent and bosuti­ nib 30–50 times more potent than imatinib (Table 110-2). Pona­ tinib inhibits vascular endothelial growth factor receptor (VEGFR), which may be partly responsible for the high incidence of hyperten­ sion observed with this agent (Table 110-2). ESTABLISHED AND EVOLVING THERAPEUTIC CONCEPTS IN CML In the early days of TKI development, the primary aim in CML therapy was to improve survival, as the therapeutic miracle of 1.0 0.8 Survival probability 0.6 0.4 Total Died TKI 2001-present Death-CML TKI 2001-present Death-CML or SCT TKI 2001-present 1996-2000 1991-1995 1983-1990 <1982 0.2 0.0 Years A CML Phase Referral Year Total Died Median (months) Accelerated Accelerated Blastic Blastic 1.0 0.8 Survival probability 0.6 0.4 0.2 0.0 B FIGURE 110-2  A. Survival in newly diagnosed chronic-phase chronic myeloid leukemia (CML) by era of therapy (MD Anderson Cancer Center experience from 1965 to present). Top blue curve is survival with tyrosine kinase inhibitors (TKIs), accounting for only CML-related deaths. The orange curve (second from top) accounts for deaths related to CML or CML treatment complications (e.g., deaths following allogeneic hematopoietic stem cell transplant [HSCT]). The red curve (third from top) is survival including all deaths regardless of causality (old age, car accidents, suicide, gun shots, second cancers, complications of unrelated surgeries, infections, others). The difference in the denominators, 613 minus 597 cases, is because 16 deaths were from unknown/undocumented causes (outside MD Anderson and no good tracking for cause of death). B. Survival in patients with accelerated- and blastic-phase CML referred to MD Anderson Cancer Center by era of therapy, demonstrating the significant survival benefit in the TKI era in accelerated-phase CML but the modest benefit in blastic-phase CML. Referred cases included de novo and post-chronic-phase transformations. TABLE 110-2  Medical Therapeutic Options in Chronic Myeloid Leukemia AGENT (BRAND NAME) APPROVED INDICATIONS DOSE SCHEDULE NOTABLE TOXICITIES Imatinib mesylate (Gleevec) All phases 400 mg daily See text Dasatinib (Sprycel) All phases First-line: 100 mg daily Salvage: 100 mg daily in chronic phase; 140 mg daily in transformation Nilotinib (Tasigna) All phases except blastic phase First-line: 300 mg twice daily Salvage: 400 mg twice daily Bosutinib (Bosulif) All phases First line: 400 mg daily Salvage: 500 mg daily Ponatinib (Iclusig) T315I mutation; failure of ≥2 tyrosine kinase inhibitors 45 mg daily (may consider lower starting doses, e.g., 30 mg daily; lower the dose to 15 mg daily once a complete cytogenetic response is achieved) Asciminib (Scemblix) Third-line therapy; T315I mutation 40 mg twice daily or 80 mg daily; T315I: 200 mg twice daily Arterial occlusive events; hypertension; (others?) Omacetaxine mepesuccinate (Synribo) Failure ≥2 tyrosine kinase inhibitors 1.25 mg/m2 subcutaneously twice daily for 14 days of induction; 7 days of maintenance every month (consider shorter dose schedules, 7 days of induction, 2–5 days of maintenance) 95% 92% 86% 67% 44% 37% 8% CHAPTER 110 1980–2000 2001–2013 1980–2000 2001–2013 p <0.001 Chronic Myeloid Leukemia 41% p <0.001 19% 5% 2% p = 0.015 Years Myelosuppression; pleural and pericardial effusions; pulmonary hypertension Diabetes; arterio-occlusive events; pancreatitis Diarrhea; liver toxicity; renal dysfunction Skin rashes (10–20%); pancreatitis (5%); arterio-occlusive events (10–20%); systemic hypertension (10–15%) Myelosuppression near-normal survival with TKI therapy was never anticipated. It was thought that CML cells would develop resistance mechanisms after a period of TKI exposure. This happened, as CML was the first tumor demonstrating the development of mutations in the ABL1 kinase domain that prevented the binding of the TKIs. However, the true resistance rate was only 10% after 10 years of imatinib expo­ sure. The TKIs were developed at a dose level below the maximum tolerated dose (MTD; traditional development of chemotherapy agents in cancer), based on the toxicities noted in the first one to two courses or few months of therapy. As the success of therapy required treatment continuation for years, or even a patient’s life­ time, additional unanticipated toxicities were observed with longterm exposures. This shifted the concept to develop these targeted therapies in CML (and in other cancers) at an “optimal biologic dose” (OBD; a dose that presumably maintains the same efficacy but reduces toxicities). Such OBDs were derived initially from clini­ cal experience in CML, although ongoing trials are basing them on translational studies of the drug exposure and target modulation, compared with preclinical research findings. This led, in CML, to study dasatinib 50 mg daily as frontline therapy, which proved to be as effective and less toxic than 100 mg daily. Similar results were reported with other TKIs where dose adjustments after achiev­ ing a good molecular response maintained efficacy. Other early concepts included the following: (1) changing a TKI if evidence of toxicity (rather than lowering the TKI dose, with the concern being that lowering the TKI dose will compromise efficacy and cause resistance); (2) changing a TKI if the National Comprehensive Cancer Network (NCCN)/European Leukemia Network (ELN) landmark-defined milestones of “failure” or “warning” were noted; and (3) changing TKI therapy in a responding patient (MMR or even MR4), in order to achieve a complete molecular response and aim for a TFR status. As experience matured, it was noted that such strategies may be harmful, as they increased the cost of therapy and increased the risk of potential additional side effects, without ben­ efiting patients. At present, therapy of CML may consider lowerdose schedules of TKIs as frontline or later-line therapy; reducing the TKI dose once a good molecular response (≥MR2) is achieved; not changing TKI therapy in patients in good molecular response; and perhaps not changing TKI therapy based on the NCCN/ELN milestones (as the long-term follow-up data showed survival to be favorable even among patients who did not achieve these molecular milestones). These concepts will be discussed further. PART 4 Oncology and Hematology At the beginning of the TKI experience, survival prolongation was the primary goal of therapy, but once near-normal survival was accomplished, investigators started addressing additional treatment endpoints. Thus, a second treatment goal was whether CML is cur­ able (defined, as in other cancers, as the ability to stop TKI therapy without disease recurrence after several years of observation). This led to studies aimed at stopping TKI therapy after 2–5 years of durable DMR and achieving a TFR status. The third treatment goal is to make TKI therapies available and affordable to all patients (rather than the few who can afford them), a problem addressed with the availability of generic TKIs. The fourth treatment goal is to minimize the early and long-term toxicities (currently addressed with studies investigating the OBDs of TKIs). Frontline Therapy of CML  Imatinib, dasatinib, bosutinib, and nilo­ tinib are all acceptable frontline therapies in CML. The long-term results of imatinib are very favorable. The 10-year cumulative rate of MMR is 90%, and of DMR 80%. The 10-year survival rate was 82%, and 10-year relative (compared with age-matched population) survival rate 92%. About 25% had to change to second-generation TKIs, 10% because of resistance to imatinib and 15% for other reasons (adverse events). The 10-year incidence of blastic-phase CML was 5.8%. In multiple randomized studies, (e.g., ENESTnd, DASISION, BFORE), the second-generation TKIs resulted in bet­ ter outcomes in early surrogate endpoints (higher rates of MMR and MR4.5; lower rates of blastic transformation). However, none showed survival benefit. This may be because the rate of complete cytogenetic response (MR2) was ultimately similarly high with ima­ tinib versus second-generation TKIs and because later-line salvage TKI therapy (following close observation and treatment change at progression) provided highly effective therapy; this ensured adequate long-term outcome despite resistance or intolerance to initial imatinib therapy. The choice of TKI frontline CML therapy depends on several factors: (1) the treatment aims (survival, TFR), which are tightly linked to age; (2) the TKI cost and affordability (generic vs patented TKIs); and (3) the patient comorbidities (e.g., avoid dasatinib if his­ tory of lung injury or chronic lung disease; avoid nilotinib if history of pancreatitis, diabetes mellitus, or arterio-/veno-occlusive spastic events; avoid bosutinib if history of liver or renal dysfunction of gastrointestinal problems [colitis, diverticulitis]). In general, if survival is the treatment aim in CML, all four TKIs achieve similar outcomes. However, if TFR is the treatment aim, then secondgeneration TKIs may be preferred. Second-generation TKIs may also be preferred in high-risk chronic-phase CML. Two additional important aims include the comparative long-term toxicities and the TKI treatment value. The frontline TKI dose schedules are as follows: imatinib 400 mg orally daily; dasatinib 100 mg orally daily; bosutinib 400 mg orally daily (use dose escalation of 100–200 mg daily for 1–2 weeks, 300 mg daily for 2 weeks, then 400 mg daily to avoid the early self-limited gastrointestinal toxicity [diarrhea, nausea, and vomiting]); and nilotinib 300 mg orally twice a day (on an empty stomach). Dasat­ inib 50 mg orally daily is as effective in frontline therapy as 100 mg daily and significantly less toxic. A recent randomized trial compared asciminib to investigator’s TKI of choice in frontline CML therapy. The 12-month MMR was significantly higher with asciminib versus other TKIs (68% vs 49%; p<.001) and with asciminib versus imatinib (69% vs 40%); p<.001), but not with asciminib versus second-generation TKIs (66% vs 58%). Whether the higher MMR rate will translate into better longterm survival or TFR rates, lower long-term side-effects, or better treatment value is an open question. Management of TKI Toxicities  In the first 10–15 years of the TKI experience, it was common practice to change TKI therapy when toxicities occurred because of the erroneous assumption that reducing the TKI dose may reduce efficacy. This was not borne out in the long-term experience, particularly in patients who are in good molecular response. Among such patients, the TKI dose can be reduced for mild-moderate or even severe reversible toxicities. Imatinib can be reduced to 100–300 mg daily, dasatinib to 20–50 mg daily, nilotinib to 200 mg daily or 150 mg twice daily, bosutinib to 100–300 mg daily, and ponatinib to 15–30 mg daily, depending on the toxicities and molecular response. Side effects of TKIs are generally mild to moderate, although with long-term TKI therapy, they could affect the patient’s quality of life. Serious side effects occur in <5–10% of patients. With ima­ tinib therapy, common mild to moderate side effects include fluid retention, weight gain, nausea, diarrhea, skin rashes, periorbital edema, bone or muscle aches, fatigue, and others (rates of 10–20%). In general, second-generation TKIs are associated with lower rates of these bothersome adverse events. However, dasatinib 100 mg daily is associated with higher rates of myelosuppression (20–30%), particularly thrombocytopenia; pleural (10–25%) or pericardial effusions (≤5%); and pulmonary hypertension (<5%). A lower dose of dasatinib (50 mg daily instead of 100 mg daily) used in frontline CML therapy resulted in similar efficacy and a lower incidence of serious side effects (pleural effusions <5%, myelosuppression <10%). Nilotinib is associated with higher rates of hyperglycemia (10–20%), pruritus and skin rashes, hyperbilirubinemia (typically among patients with Gilbert’s syndrome and mostly of no clinical consequences), and headaches. Nilotinib is also associated with occasional instances of pancreatitis (<5%). Nilotinib 300–400 mg twice daily is associated with a 10-year cumulative incidence of cardiovascular complications of 25–35%. Bosutinib is associated with higher rates of liver toxicity, renal dysfunction, and early and self-limited gastrointestinal adverse events, particularly diar­ rhea. Occasionally, the gastrointestinal symptoms mimic chronic severe enterocolitis, which reverses with treatment discontinuation. Ponatinib 45 mg daily is associated with higher rates of serious skin rashes (10–15%), pancreatitis (10%), elevations of amylase/ lipase (10%), and systemic hypertension (50–60%; severe in 20%). Arterio-occlusive events (cardiovascular, cerebrovascular, and peripheral arterial) have been reported with most TKIs. The inci­ dence appears to be highest with ponatinib, but both nilotinib and dasatinib are associated with these events at an incidence significantly higher than imatinib or bosutinib. Among the TKIs, imatinib and bosutinib are associated with the lowest incidence of cardiovascular events. With long-term follow-up, rare but clinically relevant serious toxicities are emerging. Renal dysfunction and occasionally renal failure (creatinine elevations >2–3 mg/dL) are observed in 2–3% of patients, more frequently with imatinib and bosutinib than other TKIs, and usually reverse with TKI discontinuation and/or dose reduction. Rarely, patients may develop TKI-related peripheral neuropathy or even central neurotoxicities that are misdiagnosed as dementia or Alzheimer’s disease; these may reverse slowly after TKI discontinuation. Some toxicities are prohibitive and require a change of TKI therapy: recurrent pleural effusions (most commonly with dasat­ inib; least with imatinib and nilotinib; responsive to a short course of steroids); vasospastic or vaso-occlusive events (cerebrovascular accidents, myocardial infarction or unstable angina; more common with ponatinib and nilotinib; least with imatinib and bosutinib); pulmonary hypertension (1–2% with dasatinib, but can occur with other TKIs; slowly reversible with a short course of steroids and sildenafil citrate), pancreatitis (2% with nilotinib, 2–4% with ponatinib); neurologic problems (dementia-like, parkinsonism; rare and slowly reversible with TKI discontinuation); immunemediated events (pneumonitis, myocarditis, pericarditis, hepatitis, nephritis; usually reversible with TKI discontinuation and a short course of high-dose steroids [e.g., methylprednisolone 50 mg twice daily for 3–5 days]); and severe colitis (bosutinib; reversible with discontinuation). When switching TKI therapy for prohibitive toxicity, the dose of the new TKI does not have to be the dose recommended for “failure” (a term that historically encompassed resistance and intolerance). Many of these patients are already in good molecular response, and the dose of the new TKI used for previous TKI intolerance can be lower, particularly if the patient is already in ≥MR2: dasatinib 20–50 mg daily; bosutinib 100–300 mg daily; nilotinib 200 mg daily or 150 mg twice a day; ponatinib 15–30 mg daily. TKI cross-intolerance may be more common than previously thought. Because the TKIs have different chemical structures, cross-intolerance was thought to be uncommon. With experience, it appears that patients who have intolerance to one TKI may more often have intolerance to others, with the intolerance/side effect manifesting as the same or as a different one. Discontinuation of TKIs and TFR  Several studies have confirmed that TKI discontinuation among patients who achieve DMR (MR4) for longer than 2–3 years can result in TFR rates of 40–60%. Discon­ tinuation of TKI therapy after 5+ years of DMR is associated with TFR rates of 80%+. Since the incidence of durable MR4 is 60–80%, ~30–60% of all patients with CML on TKI therapy may potentially achieve TFR with optimization of the current TKI strategies. Sug­ gested conditions to attempt TFR include low or intermediate Sokal risk CML in first chronic phase (no evidence or history of transfor­ mation); quantifiable BCR::ABL1 transcripts (e13a2, e14a2); longterm TKI therapy (5+ years); and documented DMR for >2–5 years. Once TFR is attempted, patients should be monitored molecularly every 1.5–2 months in the first 6–12 months, every 2–3 months in the second year, and then every 3–6 months in subsequent years (perhaps for up to 6–8 years of TFR status). TKIs should not be restarted unless the BCR::ABL1 transcripts (IS) increase to >0.1% (documented at least twice). Management of TKI Resistance  Resistance to a TKI refers today to BCR::ABL1 transcripts (IS) >10% after 6 months of TKI frontline therapy or BCR::ABL1 transcripts (IS) >1% after 12+ months of frontline TKI therapy. The NCCN and ELN updates of the criteria for resistance and suboptimal response have evolved over time, settling on more conservative criteria to change TKI therapy. The long-term follow-up studies have shown that patients who previ­ ously met suboptimal or resistance criteria still had excellent longterm survival without changing TKI therapy. For example, older patients with persistent BCR::ABL1 transcripts (IS) 1–10% at 2 years of imatinib therapy still had 10-year survival rates similar to those with transcripts <1%. Before switching TKI therapy for resistance, it is important to check for BCR::ABL1 kinase domain mutations. About 50% of patients with TKI resistance have BCR::ABL1 mutations that may selectively respond to particular TKIs. For example, muta­ tions involving Y253H, E255K/V, and F359V/C/I respond better to dasatinib or bosutinib. Mutations involving V299L, T315A, and F317L/F/I/C respond better to nilotinib. T315I mutations require therapy with ponatinib or asciminib and serious consideration of allogeneic HSCT. CHAPTER 110 Dasatinib, bosutinib, nilotinib, ponatinib, and asciminib are approved for CML salvage therapy. The second-generation TKIs are excellent second-line therapies after imatinib frontline resistance. In patients with resistance to one second-generation TKI, switch­ ing to another second-generation TKI yields poor results (MR2 rate 10–20%; unless specific guiding mutations), and switching to ponatinib is indicated. Ponatinib is a very potent TKI with high activity in T315I-mutated CML and in CML after two TKI expo­ sures (particularly if there is resistance to a second-generation TKI). In third-line therapy, ponatinib produces high molecular response rates and improves survival compared with second-generation TKIs. Asciminib is approved as third-line therapy and for T315Imutated disease. Chronic Myeloid Leukemia The TKI dose schedule in later-line therapy for CML resistance is as follows: dasatinib 100 mg daily; nilotinib 400 mg twice daily; bosutinib 500 mg daily; ponatinib 45 mg daily; and asciminib 40 mg twice daily or 80 mg once daily or 200 mg twice daily in T315Imutated CML. Because ponatinib 45 mg daily may be associated with serious side effects, a response-directed dose-adjusted regi­ men (starting dose of 45 mg and reduction to 15 mg once MR2 is achieved) was investigated and resulted in a lower incidence of arterio-occlusive events. TKI later-line therapy in chronic-phase CML with dasatinib, nilotinib, bosutinib, ponatinib, or asciminib is associated with MR2 rates of 30–80%, depending on the line of therapy (second vs later), CML status (cytogenetic/molecular relapse vs hematologic relapse), prior response to other TKIs, number of prior TKIs used, and the mutations at the time of relapse. The estimated 6- to 8-year survival rates with second-generation TKIs as second-line therapy are 65–75% (compared with <30–40% before their availability). Ponatinib third-line therapy resulted in an MR2 rate of 50–60%, MMR rate of 40%, and a 5-year overall survival rate of 70–75%. Its results appear even surprisingly better in real-word data: MR2 rate 80%, MMR rate 70–75%, and MR4 rate 40%. ALLOGENEIC HEMATOPOIETIC STEM CELL TRANSPLANT Allogeneic HSCT, a curative modality in CML, is associated with long-term survival rates of 50–70% when implemented in chronic phase. It carries the risk of complications related to myelosuppres­ sion, infections, and graft-versus-host disease (GVHD). Conse­ quently, the early (1-year) mortality rate is 5–30%, and 10–15% of patients die in the subsequent 1–2 decades from long-term com­ plications of the transplant (rather than from CML relapse). These are related to GVHD, organ dysfunction, development of second cancers, occasional late relapses, and hazard ratios for mortality higher than in the normal population. Other significant morbidi­ ties include infertility, chronic immune-mediated complications, cataracts, hip necrosis, and other morbidities affecting quality of life. The cure and early mortality rates in chronic-phase CML are also associated with several factors: patient age, duration of chronic phase, whether the donor is related or unrelated, degree of match­ ing, preparative regimen, and others. In accelerated-phase CML, the cure rates with allogeneic HSCT are 30–50%, depending on the definition of accelerated disease. Patients with clonal evolution as the only criterion have cure rates of 40–50%. Patients undergo­ ing allogeneic HSCT in second chronic phase have cure rates of 40–50%. The cure rates with allogeneic HSCT in blastic-phase CML are ≤20%. Post–allogeneic HSCT strategies in the setting of molecu­ lar or cytogenetic relapse include the use of TKIs for prevention or treatment of relapse, donor lymphocyte infusions, and second allogeneic HSCTs, among others. TKIs are successful at reinducing cytogenetic/molecular remissions in the setting of cytogenetic or molecular relapse after allogeneic HSCT. Choice and Timing of Allogeneic HSCT  Allogeneic HSCT was considered first-line CML therapy before 2000. The positive experi­ ence with TKIs has now relegated its use as a later-line approach. It should be considered in any patient in chronic-phase CML who develops resistance to a second-generation TKI or with a T315I-mutated disease. Relying on third-generation TKIs in these settings as long-term therapy can be very expensive ($250,000 to $1.5 million per year) and may be associated with serious toxici­ ties. Among patients who present with or evolve to blastic phase, combinations of chemotherapy and TKIs should be used to induce remission, followed by allogeneic HSCT as soon as possible. The same applies to patients who evolve from chronic to accelerated phase. Patients with de novo accelerated-phase CML may do well with long-term TKI therapy (estimated 8-year survival rate 75%). Older patients with CML (age 65–70 years or older) have a reason­ able CML-specific 10-year overall survival rate even with persistent molecular disease after 2 years of TKI therapy, with BCR::ABL1 transcripts (IS) 1–10%, or even > 10%. Such patients may opt to continue on daily TKI therapy alone or with the addition of other agents (hydroxyurea, decitabine, low-dose cytarabine). They can then remain in chronic-phase CML disease without MR2 and avoid the adverse events and poorer quality of life associated with allogeneic HSCT. MONITORING THERAPY IN CML Achievement of complete cytogenetic response by 12 months of imatinib therapy and its persistence later, the only consistent prog­ nostic factor associated with prolonged survival, is now the main therapeutic endpoint in CML. Failure to achieve a complete cyto­ genetic response by 12 months or occurrence of later cytogenetic or hematologic relapse is considered as treatment failure and an indication to change therapy. Because later-line TKI therapy may re-establish good outcome, it is important to ensure patient compliance to continued TKI therapy and change therapy when cytogenetic relapse is confirmed unless this is related to nonad­ herence. Patients on frontline imatinib therapy should be closely monitored until documentation of complete cytogenetic response, at which time they can be monitored every 6 months with periph­ eral blood PCR or more frequently (e.g., every 3 months) if there are concerns about changes in BCR::ABL1 transcripts. Cytogenetic relapse on imatinib is an indication of treatment failure and need to change TKI therapy. Mutational analysis in this instance helps in the selection of the next TKI and identifies mutations in 30–50% of patients. Mutational studies by standard Sanger sequencing (which is the technique currently available in most clinical laboratories) in patients in complete cytogenetic response (in whom there may be PART 4 Oncology and Hematology concerns of increasing BCR::ABL1 transcripts) identify mutations in ≤5% and are therefore not indicated. Changes of TKI therapy for patients with “slow” molecular response have not been proven to be of long-term benefit compared to changes when more obvious signs of resistance appear. TREATMENT OF ACCELERATED AND BLASTIC PHASES Patients in accelerated or blastic phase may receive therapy with TKIs, preferably second- or third-generation TKIs (dasatinib, nilo­ tinib, bosutinib, ponatinib), alone or in combination with chemo­ therapy, to reduce the CML burden, before undergoing allogeneic HSCT. Response rates (major hematologic) with single-agent TKIs range from 30 to 50% in accelerated phase and from 20 to 30% in blastic phase. Cytogenetic responses, particularly complete cytoge­ netic responses, are uncommon (10–30%) and transient in blastic phase. Studies of TKIs in combination with chemotherapy show that combined TKI-chemotherapy strategies increase the response rates and their durability and improve survival. This is particularly true in CML lymphoid blastic phase, where the combination of anti-ALL chemotherapy with TKIs results in complete response rates of 70% and median survival times of 3 years (compared with historical response rates of 40–50% and median survival times of 12–18 months). This allows many patients to undergo allogeneic HSCT in a state of minimal CML burden or second chronic phase, which are associated with higher probability of long-term survival. In CML nonlymphoid blastic phase, anti–acute myeloid leukemia chemotherapy combined with TKIs results in complete remission rates of 30–50% and median survival times of 12 months (compared with historical response rates of 20–30% and median survival times of 3–5 months). In accelerated phase, response to single TKIs is significant in conditions where “softer” accelerated phase criteria are considered (e.g., clonal evolution alone, thrombocytosis alone, significant splenomegaly or resistance to hydroxyurea, but without evidence of high blast and basophil percentages). In accelerated phase, combinations frequently include TKIs with low-intensity chemotherapy such as low-dose cytarabine, decitabine, interferon α, hydroxyurea, or others. OTHER TREATMENTS AND SPECIAL THERAPEUTIC CONSIDERATIONS Interferon `  Interferon α is considered in combination with TKIs (an investigational approach) and occasionally in patients during pregnancy. Chemotherapeutic Agents  Hydroxyurea remains a safe and effec­ tive agent (at daily doses of 0.5–10 g) to reduce initial CML burden, as a temporary measure in between definitive therapies, or in com­ bination with TKIs to sustain complete hematologic or cytogenetic responses. Busulfan is often used in allogeneic HSCT preparative regimens. Because of its side effects (delayed myelosuppression, Addison-like disease, pulmonary and cardiac fibrosis, myelofi­ brosis), it is now rarely used in the chronic management of CML. Omacetaxine, low-dose cytarabine, decitabine, 6-mercaptopurine, 6-thioguanine, thiotepa, anagrelide, and other agents are sometimes useful in different CML settings to control the disease burden, usu­ ally in combination with a daily TKI. Others  Leukapheresis is occasionally used in patients presenting with extreme leukocytosis and leukostatic complications. Single doses of high-dose cytarabine or high doses of hydroxyurea, with tumor lysis management, may be as effective and less cumbersome. Pregnancy and CML  TKI therapy in the first trimester of preg­ nancy is associated with fetal malformations (2–10%). Women with CML who become pregnant should discontinue TKI therapy immediately. Among 125 babies delivered to women with CML who discontinued imatinib therapy as soon as the pregnancy was known, three babies were born with neurologic, skeletal, and renal malformations, suggesting the teratogenicity of imatinib known from animal studies. A similar experience has been reported with dasatinib, where the incidence of malformations was reported to be higher, 10–12%. Data are scant with other TKIs. Control of CML during pregnancy can be managed with leukapheresis for severe symptomatic leukocytosis in the first trimester and with hydroxyurea subsequently until delivery. TKI therapy with ima­ tinib (but not dasatinib; scant data with nilotinib or bosutinib), if indicated, may be safe after 20 weeks of gestation and in the third trimester. There are reports of successful pregnancies and deliveries of normal babies with interferon α therapy and registry studies in essential thrombocytosis, but interferon α has side effects that may be troublesome during pregnancy, can be antiangiogenic, and may increase the risk of spontaneous abortions. Cytogenetic Abnormalities in Ph-Negative Cells; Mutations and CML  Approximately 5% of patients on TKI therapy and in cytogenetic/molecular response may develop chromosomal abnormalities in the Ph-negative cells. These may involve loss of chromosome Y, trisomy 8, 20q–, chromosome 5 or 7 abnormalities, and others. Most chromosomal abnormalities disappear spon­ taneously and may be indicative of the genetic instability of the hematopoietic stem cells that predisposes the patient to develop CML in the first place. Rarely (in <1% of instances), abnormalities involving chromosomes 5 or 7 may be truly clonal and evolve into myelodysplastic syndrome, acute myeloid leukemia, or myelo­ proliferative neoplasms. This is thought to be part of the natural course of patients in whom CML was suppressed and who live long enough to develop other hematologic malignancies. The presence of mutations (ASXL1, DNMT3A, RUNX1, TET2, EZH2, IDH1/2) at diagnosis or later during CML was discussed earlier. ■ ■GLOBAL ASPECTS OF CML Routine physical examinations and blood tests in the United States and advanced countries result in early detection of CML in most patients. About 50–70% of patients with CML are diagnosed incidentally, and high-risk CML as defined by prognostic models (e.g., Sokal risk groups) is found in only 10% of patients. This is different in emerging nations where most patients are diagnosed following evaluation for symptoms and many present with high tumor burden, such as massive splenomegaly, and advanced phases of CML (high-risk CML docu­ mented in 20–30%). Therefore, the prognosis of such patients on TKI therapy may be worse than the published experience. The high cost of TKI therapies (annual costs of $120,000–270,000 in the United States; lower but variable in the rest of the world) makes the general affordability of such treatments difficult. Fortunately, in 2024, some imatinib generic formulations cost about $500/year in the United States and worldwide. Generic dasatinib is also available in many geographies, and generic formulations of bosutinib, nilotinib, and ponatinib may become available by 2027. Therefore, in frontline CML therapy, if survival is the treatment endpoint, generic imatinib is a good choice. If TFR is the endpoint, generic dasatinib (50 or 100 mg daily) is a good choice. Although TKI treatment penetration is high in nations with universal health care and where cost of therapy is not an issue (e.g., Europe, Canada, Australia, United Kingdom), it may be less so in other nations, even in advanced ones like the United States, where out-of-pocket expenses may be prohibitive to a subset of patients. The estimated 10-year survival rate in CML is >85% in single-institution or national studies in countries with TKI affordability (Sweden) (Figs. 110-2 and 110-3), whereas the estimated 10-year survival rate worldwide is likely to be <50%. The Surveillance, Epidemiology, and End Results (SEER) data from the United States report an estimated 5-year survival rate of 70% in the era of TKIs. It appears that the treatment penetra­ tion of imatinib and other TKIs into CML therapy worldwide is still not optimal. The current high cost of TKI therapies, particularly in later-line therapy, encouraged considering allogeneic HSCT as third-line therapy (one-time cost of $20,000–500,000) despite the associated mortality and morbidities. Safe and effective generic TKIs should be preferred frontline and second-line therapies in CML, precluding the necessity 1.0 0.8 0.6 Overall survival 0.4 0.2 Chronic phase Accelerated phase Blast crisis 0.0 Years after diagnosis No. at risk CP AP BC CHAPTER 110 FIGURE 110-3  Survival in chronic (CP), accelerated (AP), and blastic phase (BP) phases of chronic myeloid leukemia (CML) in the population-based Swedish national registry study. The accelerated- and blastic-phase cases are de novo presentations. The favorable outcome with de novo blastic phase may be due to use of 20% blasts or more to define blastic phase. (From Dr. Martin Hoglund, Swedish CML Registry, 2013.) Chronic Myeloid Leukemia of an allogeneic HSCT until evidence of resistance to generic secondgeneration TKIs. ■ ■FURTHER READING Cortes JE et al: Bosutinib versus imatinib for newly diagnosed chronic myeloid leukemia: Results from the randomized BFORE Trial. J Clin Oncol 36:231, 2018. Cortes JE et al: Ponatinib efficacy and safety in Philadelphia chromosome-positive leukemia: Final 5-year results of the phase 2 PACE trial. Blood 132:393, 2018. Gener-Ricos G et al: Low-dose dasatinib (50 mg daily) frontline therapy in newly diagnosed chronic phase chronic myeloid leukemia: 5-year follow-up results. Clin Lymphoma Myeloma Leuk 23:742, 2023. Haddad FG, Kantarjian H: Navigating the management of chronic phase CML in the era of generic BCR::ABL1 tyrosine kinase inhibi­ tors. J Natl Compr Canc Netw 22:e237116, 2024. Hochhaus A et al: Asciminib in newly diagnosed chronic myeloid leukemia. N Engl J Med 391:885, 2024. Kantarjian H et al: Long-term outcomes with frontline nilotinib ver­ sus imatinib in newly diagnosed chronic myeloid leukemia in chronic phase: ENESTnd 10-year analysis. Leukemia 35:440, 2021. Kantarjian HM et al: Revising six established practices in the treat­ ment of chronic myeloid leukaemia. Lancet Haematol 10:e860, 2023. Kantarjian HM: What is the impact of failing to achieve TKI therapy milestones in chronic myeloid leukemia. Leukemia 37:2324, 2023. Mahon FX et al: European Stop Tyrosine Kinase Inhibitor Trial (EURO-SKI) in chronic myeloid leukemia: Final analysis and novel prognostic factors for treatment-free remission. J Clin Oncol 42:1875, 2024. Senapati J et al: Management of chronic myeloid leukemia in 2023: Common ground and common sense. Blood Cancer J 13:58, 2023. Shih YT et al: Treatment value of second-generation BCR-ABL1 tyro­ sine kinase inhibitors compared with imatinib to achieve treatment-free remission in patients with chronic myeloid leukaemia: A modelling study. Lancet Haematol 6:e398, 2019. # 41 - 111 Acute Lymphoid Leukemia ### 111 Acute Lymphoid Leukemia Dieter Hoelzer Acute Lymphoid Leukemia In acute lymphoblastic leukemia (ALL), the malignant clone arises from hematopoietic progenitors in the bone marrow or lymphatic system resulting in an increase of immature nonfunctioning leukemic cells. Infiltration of bone marrow leads to anemia, granulocytopenia, and thrombocytopenia with the clinical manifestations of fatigue, weakness, infection, and hemorrhage. These symptoms are more often the reason a patient first seeks medical advice rather than consequences of tumor bulk, such as lymph node enlargement, hepatosplenomegaly caused by leukemic infiltration, or symptoms of the central nervous system (meningeosis leukemica). ■ ■INCIDENCE AND AGE ALL is the most frequent neoplastic disease in children with an early peak at the age of 3–4 years. The incidence in adults ranges from 0.7 to 1.8/100,000 per year, being somewhat higher in adolescents and young adults (AYAs), decreasing in adults but increasing again in elderly peo­ ple. Thus, Philadelphia chromosome–positive ALL (Ph+ ALL; BCR/ ABL translocation) is observed in half of the elderly B-lineage patients. The frequency of immunologic, cytogenetic, and genetic subtypes changes substantially with age. PART 4 Oncology and Hematology ■ ■ETIOLOGY The etiology of acute leukemias is unknown. Internal and external factors influence the incidence of leukemia. Exposure to ionizing radiation or to chemicals, including prior chemotherapy, is associated with an increased risk of developing leukemia, more often observed in acute myeloid leukemia (AML). However, increasingly, second­ ary ALLs have been observed, particularly after cytostatic treatment with alkylating agents and topoisomerase inhibitors as treatment for primary tumors, most often for AML, myelodysplastic syndromes, or breast cancer. ■ ■CONGENITAL DISORDERS Patients with some rare congenital chromosomal abnormalities have a higher risk of developing acute leukemia (e.g., Klinefelter’s syndrome, Fanconi’s anemia, Bloom’s syndrome, ataxia-telangiectasia, and neuro­ fibromatosis). Those with Down’s syndrome have a 20-fold increased incidence of leukemia; ALL is increased in childhood and AML at an older age. ■ ■INFECTIOUS AGENTS No direct evidence implicates viruses as a major cause of human acute leukemia. However, viruses are involved in the pathogenesis of two lymphoid neoplasias. In the endemic African type of Burkitt’s lymphoma, the Epstein-Barr virus, a DNA virus of the herpes family, has been implicated as a potential causative agent (see Chap. 199). Endemic infection with human T-cell leukemia virus I in Japan and the Caribbean has been shown to be an etiologic agent for rare cases of adult T-cell leukemia/lymphoma (see Chap. 207). ■ ■DIAGNOSIS AND CLASSIFICATION The diagnosis of acute leukemia is first made by examination of the peripheral blood and bone marrow. For further classification of the leukemic blast cells, cytochemical stains, immunologic markers, and cytogenetic and molecular analysis are required. The immunologic markers are still the major criteria to subdivide into B-cell lineage or T-cell lineage ALL leukemias. ■ ■PERIPHERAL BLOOD Peripheral blood counts and a differential count from a WrightGiemsa–stained blood smear are essential at the time of presentation. TABLE 111-1  Laboratory Values at Diagnosis of Acute Lymphoblastic Leukemia (ALL) ALL NO. Initial white blood cell count (× 109/L) <10 10–50 >50–100 >100 41% 31% 28% 16% Neutrophils (× 109/L) <50–100 <100,000 12% 16% Platelets (× 109/L) <20 21–40 41–100 >100 22% 22% 29% 27% Hemoglobin (g/dL) <7 7–9 >9 20% 33% 47% Leukemic blasts in peripheral blood 0% 25–75% >75% 8% 34% 36% Leukemic blasts in bone marrow <50% 51–90% >90% 4% 25% 71% Source: Data from three consecutive German Multicenter Trials for Adult ALL (GMALL). The white blood cell (WBC) count in ~40% of ALL patients is reduced or normal (Table 111-1). Only 16% of patients have a WBC above 100 × 105/L. It is noteworthy that in 8% of ALL patients, no circulating leukemic blast cells were observed. Thus, in the frequently used auto­ matic blood cell counting, the diagnosis may not be detected. Peripheral blood characteristically shows anemia, thrombocytope­ nia, and neutropenia. Nearly one-third of patients have hemoglobin levels <7–8 g/dL. A platelet count below the critical number of 20 × 109/L, associated with the risk of bleeding, and neutropenia (neutro­ phils <0.5 × 109/L), associated with a higher risk of infection, are each noted in one-fifth of adults with ALL. ■ ■BONE MARROW EXAMINATION Bone marrow aspirates/biopsies are important to assess immunologic, cytogenetic, and genetic markers. A biopsy of the bone marrow is essential to confirm the diagnosis of acute leukemia and to distinguish between AML and ALL. The bone marrow is usually heavily packed with leukemic blast cells with >90% in ~70% of patients, and thus, the normal hemopoietic elements are greatly reduced or absent. ■ ■LUMBAR PUNCTURE The examination of the cerebrospinal fluid is an essential routine diagnostic measure for ALL. Central nervous system (CNS) leukemia is diagnosed if ≥5 cells/μL or leukemic blast cells were observed by morphology in cerebrospinal fluid. Opinions differ as to when the first lumbar puncture should be done—i.e., either delay lumbar puncture until remission is achieved to avoid seeding of the CNS with leukemic blast cells from the peripheral blood during the spinal tap or perform the lumbar puncture before treatment starts, since early recognition of CNS disease will lead to immediate CNS-specific therapy. Lumbar puncture is restricted to patients with an adequate platelet count (>20 × 109/L) and without manifest clinical hemorrhages. To eliminate poten­ tially transferred blast cells, patients should receive intrathecal metho­ trexate at the first lumbar puncture. ■ ■MORPHOLOGIC SUBTYPES IN ALL The French-American-British (FAB) classification distinguished three subgroups. L1 and L2 morphology has no clinical consequences. Only the L3 morphology, observed in up to 5% of adult patients, is indicative for mature B-cell lineage ALL (B-ALL) (see Chap. 65). ■ ■IMMUNOLOGIC SUBTYPES A series of monoclonal antibodies is employed to identify antigens expressed on the surface of leukemic cells, corresponding to the path­ ways of normal B-cell differentiation (see Fig. 113-2). The immuno­ logic classification aims to subdivide ALLs according to the presence or absence of B-cell or T-cell markers. A marker is considered positive if >20% of the cells are stained with the monoclonal antibody. There are different immunologic classifications, such as that of the European Group for the Immunological Characterization of Leuke­ mias (EGIL), with clear therapeutic implications. Table 111-2 gives a simplified correlation of immunologic subtypes, cytogenetics and molecular aberrations, and clinical characteristics. B-Cell Lineage ALL (B-ALL)  More than 70% of adult ALLs are of B-cell origin, and the most frequent immunologic subtype, common ALL, is characterized by the presence of the ALL antigen CD10 with­ out markers of relatively mature B cells such as cytoplasmic or surface membrane immunoglobulins. Pre-B-ALL (early B-ALL) is charac­ terized by the expression of cytoplasmic immunoglobulin, which is negative in common ALL, but otherwise is identical with respect to all other cell markers. Pro-B-ALL corresponds to early B-cell differentia­ tion and was formerly termed non-T-, non-B-ALL or null ALL because neither T-cell nor B-cell features could be demonstrated. This subtype is HLA-DR, terminal deoxynucleotidyl transferase, and CD19 positive and composes ~12% of adults ALL. Mature B-ALL is seen in 3–4% of adults and is also known as Burkitt’s leukemia. In mature B-ALL, blast cells express surface anti­ gens of mature B cells, including the sIgM. T-Cell Lineage ALL (T-ALL)  Approximately 25% of adult ALLs are of T-cell lineage. All cases express the T-cell antigen CD7 and cyto­ plasmatic CD3 (CyCD3) or surface CD3. According to their stage of TABLE 111-2  Immunologic, Cytogenetic, Molecular, and Clinical Characteristics of Adult Acute Lymphoblastic Leukemia (ALL) FREQUENT CYTOGENETIC ABERRATIONS SUBTYPES MARKER INCIDENCE B-lineage ALL (B-ALL) HLA-DR+, TdT+, CD19+, and/or CD79a+, and/or cyCD22+ 76% Pro B-ALL No additional differentiation markers Frequent myeloid coexpression (>50%) CD10– 112% t(4;11) (q21;q23) Common ALL CD10+ 49% t(9;22)(q34;q11) del(6q) Pre-B-ALL CD10±, cyIg+ 12% t(9;22)(q34;q11) t(1;19)(q23;p13) Mature B-ALL TdT–, CD34–, sIg+ 4% t(8;14)(q24;q32) t(2;8)(p12;q24) t(8;22)(q24;q11) TdT±, cyCD3, CD7+ 24% t(10;14)(q24;q11) t(11;14)(p13;q11) T-lineage ALL (T-ALL) Early Pro/Pre T-ALL Cortical T-ALL No additional differentiation markers, mostly CD2–/(+), SCD3–, CD1a– CD1a+, sCD3± sCD3+, CD1a– 6% 12% Mature T-ALL 6% Abbreviations: BM, bone marrow; CNS, central nervous system; WBC, white blood cells. T-cell differentiation, they may express other T-cell antigens (e.g., the E-rosette receptor CD2 and/or the cortical thymocyte antigen CD1a). Early pro/pre-T-ALL (also termed early T precursor ALL [ETP-ALL]), cortical or thymic T-ALL, and mature T-ALL can be distinguished with these markers. ETP-ALL is characterized by lack of CD1a and CD8, weak CD5 expression, and at least one myeloid/stem cell marker. Biphenotypic or Mixed Leukemias  Biphenotypic leukemias are defined as those expressing markers of both lymphoid and myeloid lineages on the same leukemic cells. Bilineage leukemias are those with two populations of blast cells with either lymphoid or myeloid antigens. It is not clear whether these patients should receive an ALL or AML treatment protocol. In pediatric studies, starting with a pediatric ALL protocol seemed preferable, which was then followed by AML consoli­ dation elements. ■ ■CYTOGENETIC AND MOLECULAR ANALYSIS Cytogenetic and molecular analyses should be performed in all cases. They are important to define ALL subtypes, can identify independent prognostic markers of disease-free survival, and may determine spe­ cific targeted therapies. The diagnostic techniques for ALL are standard cytogenetics, fluo­ rescence in situ hybridization, and reverse transcriptase polymerase chain reaction. These methods allow the detection of Ph+ ALL, with the chromosomal translocation t(9;22)(q34;q11) and the detection of the corresponding BCR-ABL1 gene rearrangement. Further ALL entities that have been identified are t(4;11)(q21;q23)/MLL-AFA4, abn11q23/MLL, and t(1;19)(q23;p13)/PBX-E2A. CHAPTER 111 Gene expression profiling, single nucleotide polymorphism array analysis, array-comparative genomic hybridization, and next-generation sequencing recognize the newly defined ALL entities: ETP-ALL and Ph-like ALL. Acute Lymphoid Leukemia GENETIC ABERRATIONS AND FUSION TRANSCRIPTS CLINICAL CHARACTERISTICS RELAPSE KINETICS AND LOCALIZATION 70% ALL1-AF4 (20% Flt3 in MLL+) High WBC (>100,000/μL) (26%) Mainly BM (>90%) 33% BCR::ABL1 with 54% IKFZ1 del >25% CDKN2A/B Higher age >50 years (24%) Mainly BM (>90%) Prolonged relapse kinetics (up to 5–7 years) 4% t(1;19)/PBX-E2A Higher age >55 years (27%) Frequent organ involvement (32%) and CNS involvement (13%) Frequent CNS (10%) Short relapse kinetics (up to 1–1.5 years) 50% NOTCH1B 33% HOX11b 5% HOX11L2b 4% NUP213-ABL1 Younger age (90% <50 years) Frequent mediastinal tumors (60%) Frequent CNS involvement (8%) High WBC (>50/μL) (46%) Frequent CNS (up to 10%) Extramedullary (6%) Intermediate relapse kinetics (up to 3–4 years) When relapsed, fast progression TABLE 111-3  Response Parameters According to Minimal Residual Disease (MRD) TERMINOLOGY DEFINITION Complete hematologic remission (CHR) Leukemic cells not detectable by light microscopy (<5% blast cells in bone marrow [BM]) Complete molecular remission/MRD negativity Patient in complete remission, MRD not detectable, ≤0.01% = ≤1 leukemia cell in 10,000 BM cells Molecular failure/MRD positivity Patient in complete hematologic remission, but not in molecular complete remission >0.01% Molecular relapse/MRD positivity Patient still in complete remission, had prior molecular complete remission, leukemic blast cells in BM not detectable (<5%) Hematologic relapse >5% blast cells in BM/blood Ph-like ALL, also known as BCR-ABL1-like ALL, is characterized by genetic lesions similar to Ph+ ALL, associated with IKZF1 (Ikaros) gene deletion, CLRF2 (gene for cytokine-like receptor-2) overexpres­ sion, and tyrosine kinase activating rearrangements involving ABL1, JAK2, PDGFRB, and several other genes; however, it is BCR-ABL1 negative. The frequency is 10% in children and 25–30% in young adults but does not increase further with age like Ph+ ALL. Treatment based on the underlying genetic lesion with BCR-ABL inhibitors (e.g., dasatinib) or JAK2 inhibitors (e.g., ruxolitinib) has so far had limited success in adults. PART 4 Oncology and Hematology ■ ■MINIMAL RESIDUAL DISEASE Minimal residual disease (MRD) is the detection of residual leuke­ mic cells that are not recognizable by light microscopy. Methods for determining MRD are based on the detection of leukemia-specific aberrant immunophenotypes by flow cytometry, the evaluation of leukemia-specific rearranged immunoglobulin or T-cell receptor sequences by real-time quantitative polymerase chain reaction, or the Frequent Chemotherapy Regimens in Adult ALL BFM-like Regimen Pre Induction Consolidation Re-Induction Consolidation Maintenance HDMTX Asp Pred Vind Adria Asp HDMTX HDAraC Vind VP16 Asp Dexa/Pred Vincristine Dauno/Ida Cyclo AraC VP16 6MP Asp Hyper-CVAD Regimen POMP ± other Dexa Vincristine Doxo Cyclo HDMTX HD AraC MRD evaluation • Prophylactic CNS treatment; intrathecal monotherapy; MTX or intratecal triple MTX, AraC, Dexa/Pred, +/– cranial irradiation (24 Gy) • MRD evaluation; material collection at diagnosis, evaluation after Induction I, Induction II, Consolidation I, then every 3 months. • Rituximab in B-lineage, nelarabine in T-lineage • Maintenance therapy, ~2 years in all subtypes (except Burkitt) FIGURE 111-1  A schematic treatment algorithm in acute lymphoblastic leukemia (ALL). 6-MP, 6-mercaptopurine; Adria, Adriamycin (doxorubicin); AraC, cytarabine; Asp, asparaginase; BFM, Berlin-Frankfurt-Münster; CNS, central nervous system; CR1, first complete remission; Cyclo, cyclophosphamide; Dauno, daunorubicin; Dexa, dexamethasone; Doxo, doxorubicin; HD, high-dose; Hyper-CVAD, hyperfractionated cyclophosphamide, vincristine, doxorubicin, and dexamethasone; Ida, idarubicin; MRD, minimal residual disease; MTX, methotrexate; POMP, mercaptopurine, vincristine, methotrexate, and prednisolone; Pred, prednisolone; Vind, vindesine; VP16, etoposide. detection of fusion genes associated with chromosomal abnormalities (e.g., BCR-ABL, MLL-AF4). The detection limit with these methods is 10−3–10−5 (0.1–0.001%). With new techniques such as next-generation sequencing (NGS) or digital droplet polymerase chain reaction (ddPCR), the sensitivity may increase to 10−5–10−6. The phenotypic aberrations are unique to each patient with ALL and can be detected in up to 95% of individuals. Collection of bone marrow at diagno­ sis for identification of patients’ individual markers is essential for follow-up of MRD. ■ ■MOLECULAR RESPONSE AFTER INDUCTION THERAPY AND IMPACT ON OUTCOME Achievement of molecular complete response/molecular remission is the most relevant independent prognostic factor for disease-free and overall survival in pediatric and adult ALL (Table 111-3). Patients with molecular complete remission after induction therapy have sig­ nificantly superior outcomes in several studies, with a disease-free survival rate of ~70% compared to <40% for MRD-positive patients. Patients with molecular failure after induction should proceed to a targeted therapy to reduce the tumor load, followed by allogeneic stem cell transplantation (SCT), if possible. ■ ■PROGNOSTIC FACTORS, RISK STRATIFICATION, AND MRD The aim of identification of prognostic parameters at diagnosis, which include age, WBC count, immunophenotype, and cytogenetic and genetic aberrations, is to stratify patients into risk groups: standardrisk patients are patients without any risk factors, and high-risk patients are those with one or more risk factors. High-risk patients are most often candidates for SCT in first complete remission (CR). MRD is thus the most important prognostic factor during therapy (Fig. 111-1); 20–30% of adult ALL patients who are MRD negative after induction will relapse. Potential reasons include loss of sensitivity, evolution of leukemic subclones, and extramedullary origin of disease. If the MRD status of a patient is not available, risk stratification should rely on clinical and laboratory risk factors evaluated at diagnosis. 6-MP MTX ± other Stem Cell Transplantation in CR1 according to risk factors/MRD ■ ■TREATMENT PRINCIPLES Treatment of ALL consists usually of pre-phase therapy, induction therapy, consolidation cycles, and maintenance treatment. Treatment should start immediately when the diagnosis of ALL is established and can later be specified or adapted when ALL subtype is known (e.g., Ph+). Pre-Phase Therapy  Pre-phase therapy consisting of glucocorti­ coids (prednisone 20–60 mg/d or dexamethasone 6–16 mg/d, both IV or PO) alone or in combination with another drug (e.g., vincris­ tine, cyclophosphamide) is usually given for ~5–7 days. It allows safe tumor reduction to avoid tumor lysis syndrome, to initiate sup­ portive therapy, such as substitution of platelets/erythrocytes, or to treat infections. The time required for pre-phase therapy will also allow time to obtain results of the diagnostic workup (e.g., cytogenetics, molecular genetics). Induction Therapy  The goal of induction therapy is the achieve­ ment of a CR or, even better, a molecular CR. With current regimens, the CR rate has increased to 80–90% and is higher for standard-risk patients (>90%) and lower for high-risk patients (~60%). Induction regimens are centered around vincristine, glucocorti­ coids, and anthracyclines with or without cyclophosphamide or cyta­ rabine. L-Asparaginase is the only ALL-specific drug and is now more intensively used in adults. Pegylated asparaginase has the advantage of a significantly longer period of asparagine depletion. Dexamethasone is often preferred to prednisone because it penetrates the blood-brain barrier and also acts on resting leukemic blast cells. Two chemotherapy regimens are widespread (Fig. 111-1). One is patterned after the pediatric BFM (Berlin-Frankfurt-Münster) pro­ tocol, which is mostly used in European adult ALL trials. Another approach is to repeat two different alternating intensive chemotherapy cycles, identical for induction and consolidation, for eight cycles, such as Hyper-CVAD (hyperfractionated cyclophosphamide, vincristine, doxorubicin, and dexamethasone) protocol, which is preferentially used in the United States but also in many other parts of the world. Postremission Consolidation  Usual protocols use six to eight courses and often contain systemic high-dose (HD) therapy to reach sufficient drug levels in sanctuary sites such as the CNS. Most often HD methotrexate (1–1.5 g/m2 and up to 3–5 g/m2) and/or HD cytara­ bine (4–12 doses at 1–3 g/m2) are administered. Maintenance Therapy  Maintenance therapy, a strategy trans­ ferred from childhood ALL, is mandatory. It consists of 6-mercapto­ purine and methotrexate plus intrathecal therapy. The potential effect of further intensification cycles during maintenance remains unclear. The duration of maintenance therapy for T-ALL and B-ALL is 2–2.5 years, except for Burkitt’s leukemia, for which a half year to 1 year is sufficient. In Ph+ ALL, patients also require maintenance therapy that should include a tyrosine kinase inhibitor (TKI), most likely the TKI that has been used during induction and consolidation therapy. It is also standard to give a TKI after allogeneic SCT. The duration of main­ tenance therapy with a TKI is also 2–2.5 years and should be guided by MRD evaluation. TKI use is often interrupted or switched to another TKI if toxicity occurs. ■ ■TREATMENT OF ALL PATIENTS ACCORDING TO AGE The outcome of ALL is strictly related to the age of a patient, with cure rates of ~90% in children, decreasing to <10% in elderly or frail patients. Thus, age-adapted protocols have emerged, where the age limits are directed by the hematologic and nonhematologic toxicities. Table 111-4 provides a summary of the best results obtained in adult ALL according to ALL subtype, age, and treatment. The major risk of relapse is in the first 2 years and is less likely after 5 years. ■ ■PROPHYLAXIS AND TREATMENT OF CENTRAL NERVOUS SYSTEM LEUKEMIA Prophylactic CNS therapy in ALL is essential in order to prevent CNS leukemia and to avoid spread of leukemic cells from the CNS back TABLE 111-4  Best Results in Recent Studies for Adult Acute Lymphoblastic Leukemia (ALL) SUBTYPE TREATMENT OVERALL SURVIVAL Burkitt’s leukemia Short intensive chemotherapy + rituximab; no SCT; no maintenance 80–90% B-lineage ALL, Ph–   AYA 15–35/45 years Pediatric inspired, few/no SCT ≥70–80%   Adults 45–55 years Intensive chemotherapy +/– SCT 50–60%   Elderly 55–70 years Less intensive chemotherapy + immunotherapy ~30%   Frail >70/75 years Various ≤10% B-lineage ALL, Ph+   Ph BCR-ABL Intensive chemotherapy + TKI +/– SCT 60–70%   Ph-like ALL Chemotherapy + dasatinib/JAK inhibitors ≤50% T-lineage ALL   Early (ETP) Intensive chemotherapy + nelarabine + SCT 40–50%   Cortical/thymic Intensive chemotherapy + nelarabine, no SCT 70–84% CHAPTER 111   Mature Intensive chemotherapy + nelarabine + SCT 30–50% Abbreviations: AYA, adolescent and young adult; ETP, early T precursor; Ph, Philadelphia chromosome; SCT, stem cell transplantation; TKI, tyrosine kinase inhibitor. Acute Lymphoid Leukemia to the periphery. Treatment options include intrathecal therapy, sys­ temic HD chemotherapy, and cranial radiation therapy (CRT). Wide variations exist in CNS prophylaxis regimens. Intrathecal therapy mostly consists of methotrexate as a single drug or in combination with cytosine arabinoside (AC) with or without glucocorticoids. The route of intrathecal therapy application is generally lumbar puncture. Systemic HD chemotherapy may comprise HDAC or HD methotrexate since both drugs reach cytotoxic drug levels in the cerebrospinal fluid and show effectiveness in overt CNS leukemia. CRT (18–24 Gy in 12 fractions over 16 days) is also effective as preventive treatment of CNS leukemia. Using combined modalities for CNS prophylaxis, the CNS relapse rate has decreased to 2–5%. Particular attention to CNS prophylaxis is required for targeted therapies. In Ph+ ALL, not all TKIs cross the blood-brain barrier equally such as imatinib and nilotinib but dasatinib and probably ponatinib do. In immunotherapies, intrathecal therapy is required because most antibodies do not enter the CNS. CNS involvement at diagnosis is observed in 5–10% of adult patients and is higher in mature B-ALL (up to 10–15%) and T-ALL (up to 10%). Treatment consists of the standard chemotherapy with additional intrathecal applications 3–5 times per week until blast cells are cleared in the spinal fluid. Patients with initial CNS involvement have a similar overall survival as CNS-negative patients. Relapse in CNS is usually accompanied by bone marrow involve­ ment, and if blast cells are not seen morphologically, MRD as a sign of discrete infiltration is positive in nearly all cases. CNS relapse requires local as well as systemic therapy. The outcome after CNS relapse is dis­ mal, and salvage chemotherapy followed by allogeneic SCT is the most effective option. Chimeric antigen receptor (CAR) T cells (most often targeting CD19) can cross the blood-brain barrier and achieve CRs in patients with CNS relapse. Extramedullary manifestation and relapses in ALL are often observed. Patients should have the general treatment and, if required, local intervention (e.g., local radiation if residual mediastinal mass). ■ ■STEM CELL TRANSPLANTATION SCT is an essential part of the treatment strategy for adult ALL. Peripheral blood cells are more often being used as a stem cell source, instead of bone marrow. If no matched sibling stem cell donors are available, increasingly matched unrelated donors or haploidentical donors are used. Indications for SCT in first CR are controversial. However, in most studies, SCT is recommended for high-risk patients defined either by conventional prognostic factors or by MRD positivity. High-risk patients transplanted in first CR have a survival rate of 50% or greater. Decreasing transplant-related mortality from 20–30% to 10–15% has contributed substantially to better outcomes. For standard-risk patients with sustained molecular remission, allogeneic SCT in first CR is not recommended. Autologous SCT should be restricted to MRD-negative patients, BCR-ABL–negative patients and older patients because it is less toxic but associated with a substantially higher relapse rate. For all relapsed adult ALL patients, an allogeneic SCT is thus far the only curative option. ■ ■PEDIATRIC-INSPIRED THERAPIES FOR ADOLESCENTS AND YOUNG ADULTS The principle of pediatric-inspired therapies is to have higher doses and more applications of ALL-specific drugs such as glucocorticoids, vincristine, and L-asparaginase and fewer myeloablative anthracyclines or alkylating agents, with strict adherence to time-dose intensity, thereby reducing the role of SCT. The overall survival rates for AYAs are 70–80%. ■ ■ADULT ALL The treatment results for adult ALL patients have greatly improved with more intensive chemotherapy, optimized SCT, and better sup­ portive care. In several recent multicenter prospective trials, the overall survival rate for standard-risk patients was >70% with chemotherapy alone, and for high-risk patients, the overall survival rate has increased from 20–30% to >50%. PART 4 Oncology and Hematology ■ ■ALL IN THE ELDERLY Palliative treatment regimens for elderly patients have failed, with CR rates of ~40%, a high early death rate of 24%, and a poor overall survival of only a few months. Intensive chemotherapy has also failed, with a higher CR rate of 56%, but still an early death rate of 23%, and only moderate improvement of overall survival to 14 months. Specific elderly ALL protocols with less intensive therapy based on glucocor­ ticoids, vincristine, and asparaginase, largely avoiding anthracyclines and alkylating agents, have improved outcomes. The early treatmentrelated death rate decreased to <10%, CR rates improved to ~90%, and overall survival of ~30 months was noted. Frail patients above the age of 70–75 years have very poor survival of <10%. Hopefully, this will improve with ongoing targeted therapies with either TKIs in Ph+ ALL or immunotherapies. ■ ■TARGETED THERAPIES Substantial progress in adult ALL has been made in the past decade by the introduction of new targeted therapies, including TKIs and immu­ notherapeutic approaches (Table 111-5). ■ ■TYROSINE KINASE INHIBITORS IN PHILADELPHIA-POSITIVE ALL Patients with Ph+ ALL constitute ~25% of adult B-ALL patients, with the frequency increasing to ~50% among elderly patients. In the preimatinib era, CR rates were 60–70%; survival with chemotherapy was ~10%, and after allogeneic SCT, it was ~30%. With the first-generation TKI imatinib, CR rates increased to 80–90%, the rate of BCR-ABL negativity increased from 5 to 50%, and the 5- to 10-year overall sur­ vival improved to 50–70%. Faster and deeper molecular responses are achieved with secondgeneration TKIs (dasatinib, nilotinib), and these responses apparently translate into a survival benefit. The third-generation TKI ponatinib is also effective in tumors bearing mutations (particularly T315I) that convey resistance to earlier-generation TKIs. Treating adult Ph+ ALL with an allogeneic SCT in first CR is still a good treatment option for adult patients, with a 5-year overall sur­ vival of 60–70%. In elderly patients, when low-intensity chemotherapy was combined with dasatinib, the CR rate was >90%. In a next step, by combining mini-chemotherapy with a TKI and adding immuno­ therapy with inotuzumab (an anti-CD22 antibody), the CR rate was TABLE 111-5  Targeted Therapies in Adult Acute Lymphoblastic Leukemia (ALL) Tyrosine Kinase Inhibitors (TKIs) Ph/BCR-ABL+ ALL   TKIs   Imatinib, dasatinib, nilotinib, bosutinib, ponatinib, asciminib Ph/BCR-ABL-like ALL   ABL1, ABL2: dasatinib, ponatinib; JAK2: ruxolitinib Immunologic Approaches Antibodies directed against leukemia surface antigens   Monovalent antibodies   Bivalent antibodies against the tumor and CD3 (e.g., blinatumomab) Adoptive cellular therapy   T cells engineered to kill leukemic cells Checkpoint Inhibitors   PD-1 inhibitors: pembrolizumab, nivolumab   CTLA-4 inhibitors: ipilimumab Targeted Agents   Proteasome inhibitors: bortezomib, ixazomib   BCL-2 inhibitors: venetoclax, navitoclax >90% and the overall survival improved further. A pilot experience with a chemotherapy-free regimen composed of dexamethasone, the TKI dasatinib, and the bispecific antibody blinatumomab (anti-CD19 and anti-CD3) demonstrated a CR rate of 98% and 2-year overall and disease-free survival rates of 95% and 88%, respectively. Blinatumomab eliminates Ph+ leukemic cells with resistant mutations. ■ ■IMMUNOTHERAPEUTIC APPROACHES Treatments involving monoclonal antibodies or activated T cells are currently changing the treatment paradigm of ALL. The prerequisite is that B-lineage blast cells express a variety of specific antigens, such as CD19, CD20, and CD22 (Table 111-6) that are targetable with a wide variety of monoclonal antibodies. A new treatment principle is the acti­ vation of the patient’s T cells to destroy their CD19+ leukemic blasts. Anti-CD20  The anti-CD20 monoclonal antibody rituximab has improved the outcome of patients with de novo Burkitt’s leukemia/ lymphoma. With repeated short cycles of intensive chemotherapy combined with rituximab, the overall survival increased to >80%. Rituximab is now included in most B-ALL regimens and is given at the usual dose of 375 mg/m2 on day –1 before chemotherapy for at TABLE 111-6  Expression of Antigens in B-Cell Lineage Acute Lymphoblastic Leukemia (ALL) for Potential Antibody Therapy SURFACE ANTIGEN ALL SUBTYPES EXPRESSION ON LBCa MONOCLONAL ANTIBODY CD20 Burkitt’s lymphoma/ leukemia B-precursor 86–100% 30–40% Rituximab Ofatumumab CD22 B-precursor Mature B-ALL 93–98% ~100% Inotuzumab Epratuzumab Moxetumomab pasudotox CD19 B-precursor Mature B-ALL 95–<100% 94–<100% T cell–activating therapies Blinatumomab Bispecific CD3/CD19 Chimeric antigen receptor modified T cells (CAR T cells) aDefined as ≥20% positive blast cells. Abbreviation: LBC, leukemic blast count. Source: Reproduced with permission from D Hoelzer: Novel antibody-based therapies for acute lymphoblastic leukemia. Hematology Am Soc Hematol Educ Program 2011:243, 2011. # 42 - 112 Chronic Lymphocytic Leukemia ### 112 Chronic Lymphocytic Leukemia least eight or more cycles. This leads to a significant increase in MRD negativity and improved survival. Anti-CD22  Monoclonal antibodies directed against CD22 are linked to cytotoxic agents, such as calicheamicin (inotuzumab ozo­ gamicin), or to plant or bacterial toxins (epratuzumab). In a random­ ized trial of relapsed or refractory ALL patients, the CR rate was 66% and significantly superior to the CR rate with standard chemo­ therapy. Inotuzumab is now included in first-line therapy for Ph+ and Ph– patients. Anti-CD19  Targeting CD19 is of great interest because this antigen is highly expressed in all B-lineage cells, most likely including early lymphoid precursor cells. A new promising approach is the bispecific antibody blinatumomab, which combines single-chain antibodies to CD19 and CD3, such that T cells lyse the CD19-bearing B cells. Blinatumomab is particularly effective in MRD-positive patients, with a 70–80% conversion to MRD negativity, translating into improved overall survival; ~25% of MRD-negative patients survived without any further treatment. Blinatumomab has also moved to frontline therapy. CAR-T Cells  The adoptive transfer of CAR-modified T cells directed against CD19 is a promising approach for the treatment of CD19+ childhood or adult ALL. In the first three larger studies in adults with relapsed or refractory ALL, the CR rate ranged from 67 to 91% with MRD negativity in 60–81% of the patients who achieved CR. Overall survival is 50% or more at ≥2 years, which is remarkable for these heavily pretreated patients. CAR-T cells are also effective in CNS leukemia and in other extramedullary sites. CAR-T cell therapy in relapsed or refrac­ tory ALL was first considered as a bridge to allogeneic SCT, applied in 10–50% of patients, but the necessity for an allogeneic SCT after CAR-T cells is unclear. CAR-T cell therapies are also moving to the frontline. CD19-negative relapses after CAR-T cell therapy or blinatumomab due to downregulation of CD19 expression are a relevant obstacle. Toxicities of Immunotherapies  The anti-CD22 agent inotu­ zumab ozogamicin is associated with hepatotoxicity, including venoocclusive disease, particularly after allogeneic SCT, but can be managed by reduced dosing and limitation of cycles. For anti-CD19 therapies, cytokine release syndrome and severe neurotoxicity are the most prominent toxicities and often require intensive care unit care (more so after CAR-T cells than blinatumomab). Management of these compli­ cations has improved with early recognition. Because toxic death after immunotherapies is very low compared to intensive chemotherapy or allogeneic SCT, immunotherapies are now increasingly included in frontline therapy. ■ ■TREATMENT OF T-ALL Immunotherapy for T-ALL is still not available, and intensive chemo­ therapy is still the mainstay in combination with the T cell–specific drug nelarabine. Currently, γ-secretase targeting NOTCH1, checkpoint inhibitors such as bortezomib and venetoclax, and HDAC inhibitors are being explored. ■ ■CONCLUSION AND FUTURE DIRECTIONS Cytogenetic and molecular analysis at diagnosis allows identification of ALL subentities requiring different treatment options. Evaluation of MRD is the most important parameter for treatment decisions. The greatest progress has been achieved by targeted therapies, such as TKIs for Ph+ ALL and new immunotherapeutic approaches. This will lead to further improved outcome of adult ALL patients, 50% of whom are already surviving 5–10 years and are most likely cured. New options and advances, such as low-intensity chemotherapy, reduction of SCT, incorporation of targeted therapies, and reduction of toxicities, will improve the quality of life of patients and lead to individualized approaches for each patient. ■ ■FURTHER READING Caracciolo D et al: The emerging scenario of immunotherapy for T-cell acute lymphoblastic leukemia: Advances, challenges and future perspectives. Exp Hematol Oncol 12:5, 2023. Gökbuget N et al: Diagnosis, prognostic factors and assessment of ALL in adults: 2023 ELN recommendations from a European expert panel. Blood 143:1891, 2024. Gökbuget N et al: Management of ALL in adults: 2023 ELN recom­ mendations from a European expert panel. Blood 143:1903, 2024. Hoelzer D et al: ESMO Clinical Practice Guideline interim update on the use of targeted therapy in acute lymphoblastic leukaemia. Ann Oncol 35:15, 2024. Prockop S, Wachter F: The current landscape: Allogeneic hemato­ poietic stem cell transplant for acute lymphoblastic leukemia. Best Pract Res Clin Haematol 36:101485, 2023. Ribera J-M, Chiaretti S: Modern management options for Ph+ ALL. Cancers 14:4554, 2022. Shimony S et al: Nelarabine: when and how to use in the treatment of T-cell acute lymphoblastic leukemia. Blood Adv 8:23, 2024. Short N et al: Using immunotherapy and novel trial designs to optimise front-line therapy in adult acute lymphoblastic leukaemia: Breaking with the traditions of the past. Lancet Haematol 10:e382, 2023. CHAPTER 112 Jennifer A. Woyach, John C. Byrd Chronic Lymphocytic Leukemia Chronic Lymphocytic Leukemia Chronic lymphocytic leukemia (CLL) is a monoclonal proliferation of mature B lymphocytes defined by an absolute number of malignant cells in the blood (5 × 109/L). The presence of malignant B cells under this count in the blood without nodal, spleen, or liver involvement and absent cytopenias is a precursor of this disease called monoclonal B-cell lymphocytosis (MBL) with ~1–2% chance per year of progressing to overt CLL. CLL is a heterogeneous disease in terms of natural history, with some patients presenting asymptomatically and never requiring therapy, whereas most will need therapy and a small subset will pres­ ent with symptomatic disease, require multiple lines of therapy, and eventually die of their disease. Over the past two decades, the under­ standing of CLL origin and biology has grown exponentially, leading first to more refined disease definition, prognostic markers, and, subse­ quently, introduction of novel therapies that have significantly changed the natural history of this disease to where only a small minority will die from CLL. In this way, CLL has served as a prototype of a cancer where understanding the biologic underpinnings in absence of unified mutation drivers has informed therapy development. In this chapter, we review the epidemiology, biology, and management of CLL, with a focus on new knowledge that has changed and continues to change standards of care. EPIDEMIOLOGY CLL is primarily a disease of older adults, with a median age at diag­ nosis of 71 and an age-adjusted incidence of 4.6/100,000 people in the United States; 18,740 peoples were diagnosed and 4490 people died of CLL in the United States in 2023. The prevalence of CLL has increased over the past decades due to improvements in therapy for this disease and also survival of older patients from other medical ailments. In 1980, the 5-year overall survival of patients was 70%, and this increased to 92% in 2015 and is likely even higher today. The male-to-female ratio is 2:1; however, as patients age, the ratio becomes more even, and over the age of 80, the incidence is equal between men and women. The disease is most common in Caucasians, less common in Hispanic and African Americans, and is rare in the Asian population. Unlike many other malignancies, there have been no definitive links between CLL and exposures. Indeed, CLL is one of the only types of leukemia not linked to radiation exposure. Agent Orange exposure has been implicated, and CLL is thus a service-connected condition for those who were exposed to Agent Orange in the Vietnam conflict, burn pit exposure from the Middle East conflicts, and Camp Lejune water. CLL is one of the most familial-associated malignancies, and the first-degree relative of a CLL patient has an 8.5-fold elevated risk of developing CLL than the general population. MBL is also more com­ mon in families with two first-degree relatives having CLL, further sup­ porting a genetic predisposition of this disease. Despite this, specific genes conferring risk in the familial setting outside of specific families have been difficult to identify. In genome-wide association studies (GWAS), ~30 single nucleotide polymorphisms (SNPs) have been identified, which is estimated to account for 19% of the familial risk of CLL. Genes involved in apoptosis, telomere function, B-cell receptor (BCR) activation, and B-cell differentiation have all been implicated in GWAS. Variants in shelterin complex proteins involved in telomere maintenance such as POT1 have been identified in a small number of families. BIOLOGY AND PATHOPHYSIOLOGY ■ ■CELL OF ORIGIN The cell of origin in CLL has not definitively been established. The morphology, immunophenotype, and gene expression pattern of CLL cells are that of a mature B cell (Fig. 112-1), and so it has long been presumed that the initiating cell is a mature lymphocyte, perhaps memory B cells. However, many facets of CLL biology do not support this idea, including antigen-binding characteristics of CLL cells and the presence of stereotyped BCRs. Other possibilities include a stepwise process including a series of transforming events at various stages of B-cell development, potentially including de-differentiation of more mature cells. The self-renewing, multipotent hematopoietic stem cell (HSC) might also be the originating cell of CLL, postulated based on transplant studies in mice showing clonal leukemic cell development with different characteristics from donor leukemia after transplanta­ tion of HSC from CLL patients. More work will be required to elucidate the origins of CLL. PART 4 Oncology and Hematology ■ ■B-CELL RECEPTOR SIGNALING IN CLL Perhaps the most important advancement in CLL biology is the under­ standing of the role of BCR signaling in the disease. CLL has distinct BCR signaling as compared to normal B cells, which is characterized by low-level IgM expression, variable response to antigen stimulation, and tonic activation of antiapoptotic signaling pathways that promote tumor survival. CLL cells by gene expression profiling share many features with antigen-activated mature B cells, suggesting a role for activation of BCR signaling in the disease pathogenesis. Tissue-based microarrays have revealed upregulation of BCR pathway genes in the lymph nodes and bone marrow compared to the peripheral blood, FIGURE 112-1  Chronic lymphoid leukemia in the peripheral blood. (From Williams Hematology, 7th ed, in M Lichtman et al [eds]: New York, McGraw-Hill, 2005.) suggesting a particular importance of this pathway in microenviron­ mental homing. Fitting with the role of BCR signaling in CLL, one of the most influ­ ential prognostic factors identified in this disease is the mutational status of the immunoglobulin heavy chain variable (IGHV) region. During normal B-cell maturation, the variable regions of the immu­ noglobulin heavy chain undergo somatic hypermutation. In CLL, ~60% of patients have IGHV that is ≥2% mutated from germline. This may indicate a more mature, postgerminal center progenitor, and is typically associated with a more indolent disease course. Conversely, ~40% of patients will have IGHV <2% mutated from germline, which is associated with more rapid progression of disease and short survival before the era of therapeutics that target BCR. Unfavorable biologic properties including enhanced telomerase activity, overexpression of activation-induced cytidine deaminase, increased nuclear factor-κB (NF-κB) activity, high-risk genomic mutations (e.g., NOTCH1, SF3B1, TP53, ATM), and clonal evolution are also associated with IGHV unmutated disease. In addition to the mutational status of IGHV, about 30% of CLL patients express “stereotyped” BCRs, where the stereotype subset predicts clinical course, with subsets 1 and 2 predicting higherrisk disease. ■ ■CYTOGENETIC ABNORMALITIES Besides IGHV mutational status, recurrent cytogenetic abnormalities are the most robust prognostic factor clinically available in CLL. These abnormalities are typically identified by fluorescent in situ hybridiza­ tion (FISH) analysis; however, stimulated metaphase karyotype has a role as well. The most well-characterized abnormalities include del(13) (q14.3), trisomy 12, del(11)(q22.3), and del(17)(p13.1) (Fig. 112-2). The presence of sole del(13)(q14.3) is associated with more indolent disease, prolonged survival, and good response to traditional therapies. Usually this abnormality is not seen on banded karyotype analysis, and when present on karyotype, it indicates a larger deletion involving the retinoblastoma gene, which negates the favorable prognosis associated with this marker. Trisomy 12 has a more intermediate prognosis. The del(11)(q23.3) results in deletion of the ATM gene and is associated with bulky lymphadenopathy and aggressive disease in young patients, with inferior prognosis, and more rapid progression to symptomatic disease. The del(17)(p13.1) results in loss of one allele of the tumor suppressor TP53 and is associated with the poorest prognosis in CLL with rapid disease progression, poor response to traditional thera­ pies, and shorter survival. Other abnormalities have been shown to be important in smaller studies but are not routinely performed at all centers. Finally, complex karyotype (three or more abnormalities) on stimulated metaphase karyotype analysis has significant adverse impact on time to treatment and overall survival, with data indicating that increasing complexity is even more deleterious to response and survival. Clonal evolution, or acquisition of cytogenetic or molecular abnor­ malities, is common in CLL, especially in patients with IGHV unmu­ tated CLL. Because the cytogenetics of patients can change even in the absence of therapy, it is recommended that FISH, with or without cytogenetics, is checked before every line of therapy, mostly to evaluate acquisition of del(17)(p13.1). ■ ■GENE MUTATIONS AND MIR ALTERATIONS Compared with many other malignancies, the genome in CLL is rela­ tively simple, with an average CLL genome carrying ~20 nonsynony­ mous alterations and ~5 structural abnormalities. And, unlike many other hematologic malignancies, there is no unifying genetic lesion, and most recurrent genetic driving mutations exist at frequencies of <5%. Whole genome and whole exome sequencing have identified the most common mutations in CLL to be in SF3B1, NOTCH1, MYD88, ATM, and TP53 (Table 112-1). Most of the identified mutations in these genes are common among different malignancies, and with the exception of MYD88, they are generally identified with much higher frequency in IGHV unmutated disease. NOTCH1 mutations are present in ~15% of CLL patients and are commonly associated with trisomy 12. Although multiple different Patients surviving (%) 108 120 132 144 156 168 Months No. at Risk 17p deletion 11q deletion 12q trisomy Normal 13q deletion as sole abnormality FIGURE 112-2  Outcomes among CLL patients with various cytogenetic abnormalities. (From The New England Journal of Medicine, Genomic Aberrations and Survival in Chronic Lymphocytic Leukemia, H Dohner et al: 343: 1910. Copyright @2000 Massachusetts Medical Society. Reprinted with permission from Massachusetts Medical Society.) mutations are seen, most are located within the PEST (proline, glu­ tamic acid, serine, and threonine) domain and result in constitutive NOTCH signaling. NOTCH1 mutations have been associated with lower sensitivity to CD20 antibody therapy and increased risk of transformation to aggressive diffuse large B-cell lymphoma (DLBCL; Richter’s transformation), although its relevance in the era of targeted therapies is less clear. SF3B1 is a component of the RNA spliceosome and is mutated in 10–15% of CLL cases. Mutations appear to be associ­ ated with intermediate-risk disease, and functionally, SF3B1 may be important in the response to DNA damage. Mutations of the tumor suppressor TP53 are found in ~5% of CLLs in previously untreated early-stage disease and up to 40% in later stages. TABLE 112-1  Recurrent Mutations in CLL GENE FREQUENCY OF MUTATIONS (%) SF3B1 8–14 TP53 5–13 NOTCH1 10–13 MYD88 4–8 ATM 8–11 BIRC3 <5 XPO1 <5 FBXW7 <5 POT1 <5 BRAF <5 EGR2 <5 IKZF3 <5 Abbreviation: CLL, chronic lymphocytic leukemia. 17p deletion 11q deletion 12q trisomy Normal 13q deletion as sole abnormality CHAPTER 112 Chronic Lymphocytic Leukemia Seventy percent of the time, these mutations coexist with del(17)(p13.1), effectively eliminating TP53 function. As expected, and consistent with other malignancies, TP53 mutations are associated with a poor prognosis and expected lack of response to DNA-damaging therapies. ATM mutations, which are heterogeneous and occur throughout the gene, occur in 10–15% of CLL patients. ATM mutations often coexist with del(11)(q22.3), eliminating ATM on the alternate allele. Similar to TP53, mutations in ATM tend to result in impaired response to DNA damage, which can reduce responsiveness to chemotherapy. In contrast to the aforementioned mutations, those in MYD88 tend to occur in IGHV-mutated CLL and be associated with a more indolent prognosis. This gene is involved in Toll-like receptor signaling, and the most common mutation, L265P, results in constitutive activation and NF-κB activity. Along with abnormalities in coding genes, it has become appar­ ent that noncoding genes such as microRNAs are recurrently altered in CLL. The most common cytogenetic abnormality, del(13)(q14.3), results in loss of the miR15/16 cluster, which is important in the patho­ genesis of CLL. In normal cells, miR15A/miR16A inhibits antiapop­ totic gene expression (including BCL2, CCND1, CCND3, and CDK6), and this specific deletion allows for overexpression of these genes and thus increased cell survival. Loss of other miR expression such as miR181a leads to overexpression of proteins such as the antiapoptotic genes MCL1 and TCL1. Overexpression of miR-155, an onco-miR associated with B-cell transformation, has also been documented in the majority of CLL patients. ■ ■IMMUNOLOGY CLL is characterized by dysregulation of the normal immune system in addition to the malignant immune cells. Besides numerical abnormali­ ties due to bone marrow dysfunction, even in the early stages of disease, there are skewed ratios of immune cells and functional abnormalities. Innate immune system defects associated with CLL include reduced complement proteins and activity, qualitative neutrophil defects, and functional defects of natural killer cells. More focus has been placed on the impairments in the adaptive immune system in this disease. Within the CD4+ T-cell compartment, a qualitative defect is noted similar to chronic antigen stimulation inducing a phenotype of T-cell exhaustion typical of what is seen in chronic viral infections such as hepatitis. This has been demonstrated to lead to impaired T-cell cytotoxic capacity and reduced proliferative ability. Additionally, there are physical changes in the T-cell cytoskel­ eton that cause impaired immune synapse formation with antigen presenting cells. In addition to a lack of capacity to respond to patho­ gens, the T-cell defect in CLL also likely leads to tumor cell tolerance. During the course of the disease, the polarization of the CD4+ T cells shifts from a Th1 (cytotoxic) phenotype to a Th2 phenotype, which leads to expansion of immunosuppressive cytokines such as interleukin (IL) 10. Additionally, in the later stage of disease, T regulatory cells are expanded, which contributes to an immunosuppressive phenotype. Other components of the immune microenvironment are altered as well to form a more supportive environment for the malignant cells. M2 monocytes have been shown to differentiate into a type of tumorassociated macrophage known as a nurse-like cell in CLL. These cells promote survival by secreting chemokines and cytokines that increase migration and activation. PART 4 Oncology and Hematology The humoral immune system in CLL is also dysregulated, as is expected for a malignancy that results in very few normal B cells. Hypogammaglobulinemia is very common and affects all subclasses of immunoglobulins, occurring in ~85% of patients at some time in their disease course, and is more common as disease progresses. A correla­ tion between low IgG and IgA and infection risk has been established, but isolated IgM reduction does not seem to be associated with excess infection risk. Also, CLL cells can secrete monoclonal IgM or IgG in a small number of cases, and this can correlate with disease progression. CLINICAL PRESENTATION AND DIAGNOSIS OF CLL ■ ■CLINICAL PRESENTATION AND DIAGNOSIS The presentation of CLL most commonly occurs as an incidental diagnosis made at the time of medical evaluation for another cause. In this regard, CLL is most commonly diagnosed on routine blood work demonstrating an elevated lymphocyte count in asymptomatic indi­ viduals, although some patients present with symptoms and require early therapy. When noting either an elevated total white blood cell (WBC) count with lymphocytic predominance or a normal WBC with a differential showing a lymphocytosis, the next step is to perform flow cytometry on the peripheral blood. In CLL, this will reveal the typical immunophenotype that includes the typical B-cell markers CD19, CD20, CD22, CD23, CD200, the T-cell marker CD5 (CD5 is also expressed on the B1 subset of B cells that typically has unmutated immunoglobulin and responds to antigens independent of cognate T-cell help), and dim surface immunoglobulin of either kappa or lambda type (Table 112-2). Atypical phenotypes can be seen as well and usually can be differentiated on the basis of morphology, cytoge­ netics, or clinical presentation. In cases in which the clonal B-cell count based on flow cytometry is ≥5 × 109/L, no further workup is needed to confirm the diagnosis of CLL. Some patients will present with a small clonal proliferation of CLL cells in the peripheral blood but will also have lymphadenopathy or TABLE 112-2  Typical Immunophenotype of CLL Compared with Other B-Cell Malignancies DISEASE CD5 CD10 CD19 CD20 CD23 CYCLIN D1 SURFACE IG CLL + − + + (dim) + − + (dim) Mantle cell lymphoma + − + + (mod/bright) − + + (mod/bright) Marginal zone lymphoma −/+ − + + (mod/bright) −/+ − + (mod/bright) Follicular lymphoma − + + + + −   Abbreviation: CLL, chronic lymphocytic leukemia. splenomegaly. In these cases, the likely diagnosis is small lymphocytic lymphoma (SLL), a semantic designation from CLL that denotes a pri­ marily tissue-based disease rather than bone marrow/blood-based dis­ ease. The genetic and molecular features of SLL are identical to those of CLL. The retention of the cells in tissues may be related to the expres­ sion of a particular adhesion molecule. Thus, SLL patients are managed identically to CLL patients, and often in the later stages of disease, these patients will have blood and bone marrow involvement as well. MONOCLONAL B-CELL LYMPHOCYTOSIS Patients who do not meet the diagnostic criteria for CLL based on quantification of clonal B cells in the peripheral blood and who do not have associated signs of CLL including lymphadenopathy, organo­ megaly, or cytopenias have a disorder known as monoclonal B-cell lymphocytosis (MBL), which is now thought to precede every case of CLL. Analogous to monoclonal gammopathy of uncertain significance (MGUS) in myeloma, not all MBL progresses to CLL. MBL is initially characterized by a CLL-like immunophenotype in ~75% of cases but can also be atypical (CD23 negative or bright CD20) or CD5 negative. More relevant for prognosis is characterization by count, with lowcount MBL defining patients with <0.5 × 109 clonal B cells/L and highcount MBL defining patients with >0.5 × 109 but <5 × 109/L. Patients with low-count MBL have a negligible rate of progression to CLL, whereas those with high count progress to overt CLL at a rate of 1–2% per year, warranting continued monitoring. Population-based stud­ ies have estimated the prevalence of MBL up to ~12% in the general population, where it is most common in elderly men. It is especially common in first-degree relatives of CLL patients, where the frequency is ~18%. Although the risk of MBL progression is relatively low, it has become apparent that patients still experience complications that sug­ gest an immune dysfunction in MBL that is similar to that seen with CLL. Rates of serious infections requiring hospitalization appear to be significantly increased in MBL, similar to the rates seen in CLL. In a case-control study, patients with MBL had a 16% chance of hospitaliza­ tion over a 4-year time period, compared with 18.4% in patients with newly diagnosed CLL. Secondary cancers also appear to be increased in MBL. These data suggest that monitoring for patients with MBL should focus on vaccinations and age-appropriate cancer screening, as the probability of complications appears to be higher than the risk of progression in most of these patients. Follow-up for patients with MBL can occur with the primary care physician as this does not represent a malignancy, whereas CLL is mostly co-managed with both a primary care physician and a hematologist. COMPLICATIONS OF CLL A significant amount of morbidity and mortality related to CLL is due to complications of the disease. In general, complications besides dis­ ease progression include infections, secondary cancers, autoimmune complications, and transformation to a more aggressive clonally related lymphoma. ■ ■INFECTIONS Infections are a leading cause of both disease-related morbidity and death in patients with CLL, with ~30–50% of deaths in CLL patient attributed to infection. Owing to the immune dysfunction associ­ ated with the disease, patients are at risk for both typical and atypical infections. Besides this baseline risk of infections, most CLL therapies, even targeted therapies, can increase infection risk. Viral prophylaxis is also indicated for many patients when therapy is initiated (even with targeted agents) and for patients with a history of varicella-zoster to diminish reactivation and morbidity from this virus. Because of the abnormalities in cellular and humoral immunity, vaccine responses in CLL are limited in many patients, especially in the later stages of disease. In one study, one dose of 13-valent pneu­ mococcal vaccine produced an adequate immune response in only 58% of patients compared with 100% in age-matched controls. Vaccine efficacy can be improved in CLL patients by repeated booster vaccina­ tions, vaccine adjuvants, and protein conjugation. Despite the known limitations, vaccination against influenza, COVID-19, varicella-zoster, pneumococcal pneumonia (Prevnar 20), and respiratory syncytial virus is recommended in CLL. The recombinant zoster vaccine has approximately a 60% response in previously untreated CLL, is safe, and should be considered for this patient group. Efficacy of the newer 20-valent pneumococcal vaccine in patients with CLL has not yet been reported. In contrast, live vaccines should be avoided in the setting of CLL because of the small risk of viral reactivation with an immuno­ compromised host. Vaccine effectiveness in terms of humoral response is also decreased by most CLL therapies, although this can be overcome in some cases by booster vaccinations. When possible, receiving vaccinations before the initiation of therapy is recommended. As discussed earlier, hypogammaglobulinemia is common in CLL and can be associated with significant risk for infections, primarily of mucocutaneous etiology such as sinusitis and bronchitis. In addition, women can have frequent urinary tract infections. While administra­ tion of prophylactic intravenous immunoglobulin (IVIg) has not been shown to improve survival, it has been shown to reduce the number of minor or moderate bacterial infections, and thus is indicated in patients with hypogammaglobulinemia who suffer from recurrent infections or have pulmonary bronchiectasis. It is also our practice to administer at least one dose of immunoglobulin to CLL patients who develop influenza with coexisting hypogammaglobulinemia to diminish risk of postinfluenza pneumococcal pneumonia. IVIg is also indicated in patients who have been hospitalized for a serious infection and in those whose IgG level is <300–500 mg/dL. ■ ■SECONDARY MALIGNANCIES Multiple population-based studies have shown that patients with CLL are at an elevated risk of developing other cancers, with a rate up to three times that of the general population, even in the absence of cytotoxic chemotherapy. The most common types of cancers seen in CLL are skin, prostate, and breast cancers, although other cancers are seen as well. Skin cancers are particularly common, with a rate of 8- to 15-fold higher than the general population, and may behave more aggressively. All CLL patients should be counseled on the use of sunscreen while outdoors and should undergo preventative skin examinations at least yearly. In one single-center study, older age at CLL diagnosis, male sex, high β2-microglobulin, high lactate dehydrogenase (LDH), and chronic kidney disease were associated with excess risk of other cancers; other CLL-specific risk factors have not shown association with other cancer risk. While cancer risk is higher, there are no specific recommendations for increased cancer screening in CLL patients. Age- and sex-appro­ priate screenings should be recommended. In addition, we extend screening beyond age 70–75 years for CLL patients based on the higher frequency of cancers. Conflicting data exist regarding the risk of cancers after CLL-specific therapy. Chemoimmunotherapy, in particular alkylator-containing regimens, seems to be associated with an increased risk for second­ ary cancers. Secondary cancers are also seen in the setting of targeted therapies. Bruton tyrosine kinase (BTK) inhibitors appear to have a secondary cancer risk similar to what is seen in the CLL population in general, but potentially a higher rate of nonmelanoma skin cancers. Compared with chemoimmunotherapy, venetoclax plus obinutuzumab has been associated with a numerically but not statistically higher rate of secondary cancers at follow-up of 6 years. ■ ■AUTOIMMUNE COMPLICATIONS Autoimmune complications are frequent in CLL. Most commonly, these include autoimmune cytopenias, but autoimmune complications of other organs including glomerulonephritis, vasculitis, and neu­ ropathies have also been reported. Of the autoimmune cytopenias, the most common is autoimmune hemolytic anemia (AIHA), which is an antibody-mediated destruction of autologous red blood cells (RBCs). Second most common is immune thrombocytopenia (ITP), which shares some features with AIHA and has a similar mechanism targeting platelets. These two syndromes may occur in isolation, sequentially in the same patient, or present in combination as Evan’s syndrome. Pure red cell aplasia (PRCA) and autoimmune granulocytopenia (AIG) are comparatively rare and can occur alone or in combination with other autoimmune cytopenias. It is difficult to tease out whether autoim­ mune cytopenias lead to worse prognosis in CLL because of various complicating factors. However, it is clear that these can lead to sig­ nificant morbidity, both due to the process itself and due to therapies required for management. AIHA usually presents as an isolated anemia with an elevated reticu­ locyte count and features of hemolysis including elevated bilirubin and LDH and low haptoglobin. Detection of a warm IgG antibody on the surface of RBCs with a Coombs test can help solidify the diagnosis, although Coombs-negative cases can occur. Immediate therapy is almost always necessary and consists of transfusion and immunosup­ pression. Glucocorticoids are often used for initial therapy, although in most cases, additional treatment is needed due to either poor response or recurrence with taper of steroid dosing. Rituximab can be success­ ful, and therapy directed toward the underlying CLL is often effective in more resistant cases. Transfusion of blood in cases of robust AIHA must be initiated with caution as transfusion reactions can be seen due to poorly matched blood, but it should be pursued in those with severe, symptomatic anemia. Death from uncontrolled AIHA can occur in the absence of appropriate supportive care. CHAPTER 112 Chronic Lymphocytic Leukemia ITP can be more difficult to diagnose, as it may be difficult to dif­ ferentiate from progression of disease due to the lack of laboratory tests that identify platelet destruction from this mechanism. Signs that point toward ITP include isolated thrombocytopenia and rapid decline in platelet levels in the absence of an alternative etiology. A bone mar­ row biopsy showing normal or increased megakaryocytes can be used to confirm the diagnosis but is often not necessary. In CLL, treatment for ITP is usually instituted when platelet levels drop to 20,000–30,000 or if there is evidence of bleeding complications or need for invasive procedures. Like AIHA, initial therapy consists of glucocorticoids and IVIg, with rituximab also being an effective method to induce longterm remissions. Also, the thrombopoietin receptor agonists romip­ lostim and eltrombopag are effective in secondary ITP. In many cases, ITP can be successfully treated without treating the underlying CLL. In cases in which anemia or thrombocytopenia appear, it is impor­ tant to investigate the mechanism because the approach to therapy of autoimmune cytopenias in CLL differs from that for cytopenias due to marrow replacement. ■ ■RICHTER’S TRANSFORMATION One of the most devastating complications of CLL is Richter’s trans­ formation, transformation of CLL to an aggressive lymphoma, most commonly DLBCL. The World Health Organization also recognizes Hodgkin’s lymphoma (HL) as a variant of Richter’s transforma­ tion; other aggressive lymphomas are rarely identified. Some older series have included prolymphocytic transformation in this category, although this has much less prognostic impact on long-term outcome. The prevalence of Richter’s transformation is difficult to estimate based on previous studies, but one prospective observational study estimated a rate of 0.5% per year for DLBCL and 0.05% per year for HL. Risk factors for development include bulky lymphadenopathy, NOTCH1 mutations, del(17)(p13.1), and a specific stereotyped IGVH usage. Lymphomas arising in the setting of CLL can either be clonally related or unrelated to the initial CLL, with prognosis significantly better for clonally unrelated lymphomas. In addition, patients with Hodgkin’s transformation have improved outcome when treated with standard Hodgkin’s disease treatment. B-cell prolymphocytic leukemia (PLL) arising from CLL is currently classified as Richter’s transformation as well; however, clinical features and therapy are quite different, so these two should be differentiated for therapeutic purposes. Clinical signs of Richter’s transformation include rapid progression in adenopathy, often in a specific area, and constitutional symptoms including fatigue, night sweats, fever, and weight loss. LDH is usually high. In suspected cases, the first step is 18FDG-PET/CT (fluorode­ oxyglucose–positron emission tomography combined with computed tomography) scan to localize an area for biopsy. Standardized uptake values (SUVs) <5 are consistent with CLL and can rule out Richter’s transformation in many cases. SUVs >5 are suspicious for Richter’s transformation, with SUVs ≥10 being very concerning. Excisional biopsy is the preferred mode of diagnosis, and fine-needle aspiration should be discouraged. Therapy for DLBCL Richter’s transformation usually involves com­ bination chemoimmunotherapy. Outcomes are poor, with median survivals of 6–16 months in most series for clonally related Richter’s versus ~5 years for clonally unrelated. This highlights an area of unmet need in CLL therapy and an area of active investigation. Intensive chemotherapy is ineffective for most patients and results in significant toxicity. For fit patients who achieve a response with therapy, stem cell transplantation has the possibility to induce long-term remissions and should be explored. In addition, chimeric antigen receptor (CAR) T-cell (CAR-T) therapy has shown promising results in small groups of patients and remains an area of active clinical investigation. Limited data using bispecific antibodies are also encouraging. Patients with Hodgkin’s disease can be treated according to the algorithm for this disease, with many individuals being cured. PART 4 Oncology and Hematology WORKUP OF CLL AND APPROACH TO THERAPY ■ ■WORKUP AND STAGING Workup of a patient with new diagnosis of CLL based on typical immunophenotyping includes a detailed history of infectious disease; family history of CLL; and careful physical examination with attention to the lymph nodes, spleen, and liver. In patients desiring to know the expected natural history of their CLL, prognostic testing using FISH and stimulated karyotype and sequencing for TP53 and IGHV muta­ tion status can be performed. Imaging with CT scan is usually not necessary unless there are symptoms and concern for intraabdominal nodes out of proportion to peripheral nodes. Bone marrow biopsy is not undertaken until therapy is initiated, except in cases of unexplained cytopenias. ■ ■STAGING There are two widely used staging systems in CLL: The Rai staging system is used more commonly in the United States, whereas the Binet system is more commonly used in Europe. Both characterize CLL on the basis of disease bulk and marrow failure (Table 112-3). Both rely on physical examination and laboratory studies and do not require TABLE 112-3  Staging of CLL Rai Staging System Low risk (stage 0) Lymphocytosis only Intermediate risk (stage I/II) Lymphocytosis with lymphadenopathy, with or without splenomegaly or hepatomegaly High risk (stage III/IV) Lymphocytosis with anemia or thrombocytopenia due to bone marrow involvement Binet Staging System A <3 areas of lymphadenopathy B ≥3 areas of lymphadenopathy C Hemoglobin ≤10 g/dL and/or platelets <100,000/μL Abbreviation: CLL, chronic lymphocytic leukemia. TABLE 112-4  CLL International Prognostic Index Risk Score     VARIABLE ADVERSE FACTOR RISK SCORE TP53 status Deleted or mutated IGHV mutational status Unmutated >3.5 mg/L β2-Microglobulin concentration Clinical stage Rai I–IV or Binet B–C Age >65 years Implications of Risk Score   5-YEAR SURVIVAL (TRAINING SET DATA) RISK SCORE RISK CLASSIFICATION 0-1 Low 93.2% 2-3 Intermediate 79.3% 4-6 High 63.3% 7-10 Very high 23.3% imaging or bone marrow analysis. While the initial staging systems could reliably predict survival in CLL, with the changes in therapy since the original description of the stages, the impact of initial stage on survival is not as clear. Cytogenetic and genomic testing can help refine outcome of these staging tests. An international collaboration integrated both clinical and genomic staging to better predict outcome at diagnosis and time of initial treatment, which led to development of the CLL International Prognostic Index (Table 112-4). This index has been shown to be useful in prediction of both time to first treatment and outcome with chemoimmunotherapy. Validation in the setting of novel targeted therapies has not occurred. ■ ■CRITERIA FOR THE INITIATION OF THERAPY Currently, a watchful waiting strategy is used for most patients with CLL, with therapy reserved for patients with symptomatic disease. This recommendation is based on multiple trials showing no survival advantage with earlier therapy, although this question continues to be a focus of active investigation. With the exception of patients participating in early intervention studies in CLL, disease-related symptoms that require the initiation of therapy are outlined in Table 112-5. Except for the rare patient who presents with disease requiring urgent therapy, in most cases, these symptoms can be monitored over short periods to determine related­ ness to CLL and need for therapy. ■ ■INITIAL THERAPY FOR CLL Over the past decade, the initial therapy of CLL has dramatically changed. Whereas chemoimmunotherapy was once standard for all patients, now most patients are treated with oral therapies targeted TABLE 112-5  Criteria for the Initiation of Therapy Symptoms Indicating Need for Therapy in CLL Evidence of progressive marrow failure (worsening of anemia or thrombocytopenia not due to autoimmune destruction) Massive (≥6 cm below costal margin), progressive, or symptomatic splenomegaly Massive (≥10 cm), progressive, or symptomatic lymphadenopathy Progressive lymphocytosis with an increase of ≥50% over a 2-month period or lymphocyte doubling time <6 months Autoimmune anemia or thrombocytopenia not responsive to standard therapy Symptomatic or functional extranodal involvement Constitutional symptoms (one or more of the following: unintentional weight loss ≥10% over 6 months, significant fatigue, fevers ≥100.5°F for 2+ weeks without infection, night sweats for >1 month without infection) Abbreviation: CLL, chronic lymphocytic leukemia. against BTK or BCL2 with an anti-CD20 monoclonal antibody. This continues to be an area of active investigation, with standards of care shifting rapidly. The major classes of these therapies will be outlined here. BTK Inhibitors  BTK is an attractive target in CLL because, unlike other kinases in the BCR pathway, BTK does not have natu­ ral redundancy and is relatively selective for B cells, so inhibition leads to a predominant B-cell–specific phenotype. The first-in-class covalent BTK inhibitor is ibrutinib, which is relatively selective for BTK but also inhibits a number of structurally similar kinases. As initial therapy, ibrutinib was initially compared with chlorambucil (RESONATE study), and there was an 84% lower risk of progression or death with ibrutinib, with 59% of ibrutinib-treated patients alive and progression-free at 7 years. Subsequent studies have compared ibrutinib alone or with the anti-CD20 antibody rituximab to standard chemoimmunotherapy with fludarabine plus cyclophosphamide plus rituximab (FCR) or bendamustine plus rituximab (BR) and shown superiority of targeted therapy to chemoimmunotherapy. Ibrutinib also has immune modulatory roles to expand and also enhance T-cell function that may improve CAR-T efficacy. Side effects noted to occur with this class of agents include arthralgias/myalgias, rash, diarrhea, dyspepsia, bruising/bleeding (particularly when on antiplatelet/antico­ agulation therapy or with surgery), hypertension, atrial fibrillation, and ventricular arrhythmias. Two second-generation covalent BTK inhibitors, acalabrutinib and zanubrutinib, were developed to be more specific for BTK than ibruti­ nib and consequentially show better tolerability. Two trials performed in relapsed/refractory CLL have positioned acalabrutinib and zanubru­ tinib as preferred BTK inhibitors compared with ibrutinib. Acalabru­ tinib was compared head-to-head with ibrutinib in previously treated patients with high-risk relapsed CLL in the ELEVATE-RR trial. Acala­ brutinib was shown to be noninferior to ibrutinib in terms of efficacy and to have lower rates of atrial fibrillation, hypertension, myalgias/ arthralgias, bruising, and skin and nail changes than reported with ibrutinib. Zanubrutinib was compared head-to-head with ibrutinib in the ALPINE trial, which enrolled patients with relapsed CLL without regard to risk status. In this study, zanubrutinib was shown to be supe­ rior to ibrutinib in terms of overall response rate and progression-free survival (PFS). Zanubrutinib was also associated with lower rates of atrial fibrillation but similar rates of other adverse events. Because acalabrutinib and zanubrutinib are newer, follow-up is shorter than with ibrutinib, but all three covalent BTK inhibitors appear to be similarly active in the frontline setting. Acalabrutinib was studied in the treatment-naïve setting in the ELEVATE-TN trial, where acalabrutinib resulted in a 6-year PFS of 62% and acalabrutinib given with obinutuzumab resulted in a 4-year PFS of 78%. Zanubrutinib was studied in treatment-naïve CLL in the SEQUOIA study, where 2-year PFS was 85.5% for patients treated with zanubrutinib. Importantly, with the follow-up that is available from frontline studies of covalent BTK inhibitors in CLL, traditional prognostic fac­ tors, including IGHV mutational status and FISH, have less impact on outcome. Indeed, age and performance status were the only variables that predicted survival in the ELEVATE-TN trial. BCL2 Inhibitor  Venetoclax is an orally bioavailable, selective allosteric inhibitor of the antiapoptotic protein BCL2, which is upregu­ lated in CLL. Similar to the BTK inhibitors, phase 3 trials support the frontline use of venetoclax in combination with obinutuzumab (VO) compared with chemoimmunotherapy. The CLL14 study compared VO versus chlorambucil plus obinutuzumab in previously untreated patients with coexisting medical conditions. Unlike BTK inhibitors, which are continuously administered until disease progression, VO treatment is administered for a fixed duration of 1 year. Median PFS for VO was 76.2 months, compared with 36.4 months for patients treated with chlorambucil plus obinutuzumab. The CLL13/GAIA trial also studied VO, as well as VO plus ibrutinib (IVO) and venetoclax plus rituximab (VR), compared with effective chemoimmunotherapy regimens (FCR for younger patients and BR for older patients) in fit patients. At 4 years, VO and IVO showed superior PFS compared with chemoimmunotherapy (81.8% and 85.5%, respectively, vs 77.2%), but VR was not superior to chemoimmunotherapy. Side effects associated with venetoclax include tumor lysis syndrome, neutropenia, and nau­ sea/vomiting/diarrhea. Importantly, genomic risk features including IGHV mutational status and FISH/cytogenetics appear to be more relevant to PFS with fixed-duration VO therapy as compared with indefinite BTK inhibitor therapy. Targeted Therapy Combinations  Due to synergy between BTK and BCL2 inhibition, there has been considerable interest in studies combining agents with these two mechanisms to allow for fixedduration therapies. As described earlier, 1-year fixed-duration IVO was shown to be superior to chemoimmunotherapy in previously untreated fit patients in the CLL13/GAIA study. The GLOW study is a registra­ tion trial comparing ibrutinib plus venetoclax (IV) to chemoimmuno­ therapy in previously untreated older or unfit patients. In this trial with 1 year of IV, 42-month PFS was 74.6% for IV compared with 24.8% for chlorambucil plus obinutuzumab. Although this study led to regulatory approval of IV in Europe, it is not approved by the U.S. Food and Drug Administration (FDA). It is not yet clear whether IV or IVO is a more effective therapy than the other fixed-duration standard, VO. Current studies are also using more selective inhibitors of BTK in an attempt to improve efficacy and safety of these combinations. CHAPTER 112 Chemoimmunotherapy  For the most part, targeted therapy has supplanted chemoimmunotherapy in CLL. However, long-term follow-up of studies of FCR has demonstrated that a subset of patients treated with this regimen can have durable responses over 20 years, with a likely cure of CLL. This group is composed almost exclusively of patients with mutated IGVH and favorable cytogenetics. However, despite the efficacy of this regimen, short- and long-term toxicities limit its adaptability to many patients with IGHV-mutated disease. Short-term toxicities are mostly related to myelosuppression and include neutropenia and infection. Long-term cytopenias are less com­ mon, but they do occur. Also, there is about a 3–5% risk of therapyrelated myeloid neoplasm with this regimen that is almost always fatal. In the E1912 study of FCR versus ibrutinib plus rituximab (IR), at follow-up, there was no difference in PFS or overall survival between FCR and IR for patients with mutated IGHV, suggesting that a place for this regimen may remain in clinical practice. In addition, current stud­ ies are focused on limiting chemotherapy and/or adding novel agents in efforts to achieve cure but limit toxicity. Chronic Lymphocytic Leukemia ■ ■THERAPY OF RELAPSED CLL Currently, the mainstays of treatment for relapsed CLL are the same classes as initial therapy, and the choice of second-line therapy is heav­ ily dependent on the agent that was used in the frontline setting. The optimal sequencing of targeted agents in CLL has not been established; however, the available data suggest that the sequence of either BTK inhibitor and then BCL2 inhibitor and the reverse are both accept­ able. In addition, some patients treated initially with venetoclax-based regimens can likely be successfully retreated with venetoclax. In a trial of venetoclax for patients who had relapsed after ibrutinib therapy, overall response rate (ORR) was 65%, with a median PFS of ~2 years, in a very heavily pretreated patient population. Retrospective data of a BTK inhibitor given after venetoclax suggest that this sequence is also effective, with an ORR of 84% and median PFS of 32 months. PI3K inhibitors also have activity in relapsed CLL; however, activity follow­ ing both BTK and BCL2 inhibitors is likely minimal. In addition, many new agents are in development in CLL, including novel oral targeted therapies, antibodies, and immune-based treatments. Noncovalent Inhibitors of BTK  Despite the activity of covalent BTK inhibitors in CLL, a subset of patients will eventually relapse, and the primary mechanism of acquired resistance to ibrutinib, acalabru­ tinib, and zanubrutinib is acquisition of a mutation at the binding site of the drug (predominantly BTK C481S). Noncovalent BTK inhibitors TABLE 112-6  Response Criteria in CLL LYMPHOCYTE COUNT LYMPH NODESa SPLEEN/LIVER SIZEb BONE MARROWc PERIPHERAL BLOOD COUNTS   CR <4000/μL None >1.5 cm Not palpable Normocellular, <30% lymphocytes, no B lymphoid nodules PR Decrease ≥50% from baseline Decrease ≥50% from baseline Decrease ≥50% from baseline Stable disease Not meeting CR/ PR/PD criteria Not meeting CR/PR/ PD criteria Not meeting CR/PR/PD criteria PD Increase ≥50% Increase ≥50% Increase ≥50%   • Platelet count ≤50% of baseline due to CLL • Hemoglobin decrease >2 g/dL due to CLL aRefers to sum of the products of multiple lymph nodes evaluated by CT scan. bBased on physical examination. cBone marrow only required to confirm CR. Abbreviations: CLL, chronic lymphocytic leukemia; CR, complete response; PD, progressive disease; PR, partial response. have been developed to overcome this resistance mechanism by bind­ ing both reversibly and to alternative sites on BTK. Pirtobrutinib is the first in class of these agents and is an extremely selective inhibitor of BTK that has achieved accelerated approval by the U.S. FDA for use in patients who have been previously treated with both BTK and BCL2 inhibitors. This is based on the BRUIN study, where an overall response rate of 82.2% and median PFS of 19.6 months were seen in a heavily pretreated high-risk group of patients, with equivalent efficacy noted for patients with C481S mutations in BTK. PART 4 Oncology and Hematology Immune Therapies  Immune therapies in CLL are currently focused in the relapsed setting and include allogenic stem cell trans­ plantation, CAR-T therapy, and bispecific antibodies. Stem cell transplantation is a curative approach to CLL. Because most CLL patients are older and many have significant comorbidities, myeloablative transplants incur extensive morbidity and mortality, making them prohibitive in many individuals. Reduced-intensity conditioning (RIC) allogeneic transplants have been successfully incor­ porated into the treatment of patients up to ~75 years in age but still have a ≥50% frequency of chronic graft-versus-host disease. This is still considered a standard treatment in CLL but has fallen out of favor with the introduction of well-tolerated novel agents, as well as clinical trials of CAR-T therapy. CD19 CAR-T trials have not been as successful in CLL as they have in other B-cell malignancies, due to the immunosup­ pression associated with the disease. The most robust data have come with lisocabtagene maraleucel (liso-cel), where in the TRANSCEND CLL 004 trial, the ORR was 43%, with a median PFS of 11.9 months in patients previously treated with BTK inhibitors and venetoclax. Many current trials are focused on optimizing CD19 CAR-T by add­ ing agents such as BTK inhibitors or PI3K inhibitors or modifying the CAR-T structure, and other studies are testing different targets outside of CD19. This area remains a focus of intense investigation in CLL. ■ ■ASSESSING RESPONSE TO THERAPY AND MINIMAL RESIDUAL DISEASE IN CLL Following the completion of therapy or during therapy for indefinite targeted agents, response is initially assessed using physical exami­ nation and laboratory studies (Table 112-6). If residual disease is not detected using these methodologies, CT scans are used to assess response. Bone marrow biopsies with flow cytometry are indicated if no disease is detected to confirm CR. It has been established in various malignancies that complete tumor eradication is associated with longer survival. In CLL, if no malignant cells can be detected in the bone marrow down to a level of 1 CLL cell in 104 leukocytes (0.01%), the patient is said to be negative for minimal residual disease (MRD). Following combination • Platelet count >100,000/μL • Hemoglobin >11 g/dL • Neutrophils >1500/μL Infiltrate ≤50% of baseline One of the following: • Platelet count >100,000/μL or ≥50% from baseline • Hemoglobin >11 g/dL or ≥50% from baseline • Neutrophils >1500/μL or ≥50% from baseline Not meeting CR/PR/PD criteria Not meeting CR/PR/PD criteria chemoimmunotherapy, eradication of MRD correlates with long-term survival and potentially cure in a subset of patients receiving FCR chemoimmunotherapy. Undetectable MRD in blood or bone mar­ row is also associated with improvement in PFS in venetoclax-based regimens. However, eradication of MRD has not been shown to be a meaningful endpoint with BTK inhibitors as monotherapy. Higher sensitivity of 1 CLL in 106 leukocytes (0.0001%) can be obtained using next-generation sequencing methods such as ClonoSeq. Treatment of MRD-relapsing CLL is being explored as part of clinical trials. ■ ■CONCLUSION CLL is treated only when it becomes symptomatic. At the time of ther­ apy, FCR chemoimmunotherapy in a small subset of young patients with very good risk CLL is potentially curative. In the majority of patients with symptomatic CLL, targeted therapy directed at BTK and/ or BCL2 can produce durable remissions and allow patients many years of disease-free survival. ■ ■FURTHER READING Brown JR et al: Zanubrutinib or ibrutinib in relapsed or refractory chronic lymphocytic leukemia. N Engl J Med 388:319, 2023. Byrd JC et al: Acalabrutinib versus ibrutinib in previously treated chronic lymphocytic leukemia: Results of the first randomized phase III trial. J Clin Oncol 39:3441, 2021. Fischer K et al: Venetoclax and obinutuzumab in patients with CLL and coexisting conditions. N Engl J Med 380:2225, 2019. Hallek M et al: iwCLL guidelines for diagnosis, indications for treat­ ment, response assessment, and supportive management of CLL. Blood 131:2745, 2018. Landau DA et al: Evolution and impact of subclonal mutations in chronic lymphocytic leukemia. Cell 152:714, 2013. Mato AR et al: Pirtobrutinib after a covalent BTK inhibitor in chronic lymphocytic leukemia. N Engl J Med 389:33, 2023. Puente XS et al: Whole-genome sequencing identifies recurrent muta­ tions in chronic lymphocytic leukaemia. Nature 475:101, 2011. Sharman JP et al: Acalabrutinib with or without obinutuzumab versus chlorambucil and obinutuzumab for treatment-naïve chronic lym­ phocytic leukemia (ELEVATE TN): A randomized, controlled, phase 3 trial. Lancet 395:1278, 2020. Siddiqi T et al: Lisocabtagene maraleucel in chronic lymphocytic leukaemia and small lymphocytic lymphoma (TRANSCEND CLL 004): A multicentre, open-label, single-arm, phase 1–2 study. Lancet 402:641, 2023. Thompson PA et al: Fludarabine, cyclophosphamide, and rituximab treatment achieves long-term disease-free survival in IGHV-mutated chronic lymphocytic leukemia. Blood 127:303, 2016. # 43 - 113 Non-Hodgkin’s Lymphoma ### 113 Non-Hodgkin’s Lymphoma Caron A. Jacobson, Dan L. Longo Non-Hodgkin’s Lymphoma Non-Hodgkin’s lymphomas (NHLs) are cancers of mature B, T, and natural killer (NK) cells. They were distinguished from Hodgkin’s lym­ phoma (HL) upon recognition of the Reed-Sternberg (RS) cell and dif­ fer from HL with respect to their biologic and clinical characteristics. Whereas ∼80–85% of patients with HL will be cured of their lymphoma by chemotherapy with or without radiotherapy, the prognosis and natural history of NHL tend to be more variable. NHL can be classi­ fied as either a mature B-NHL or a mature T/NK-NHL depending on whether the cancerous lymphocyte is a B, T, or NK cell, respectively. Within each category are lymphomas that grow quickly and behave aggressively, as well as lymphomas that are more indolent, or slow growing, in nature. For a list of the World Health Organization (WHO) classification of lymphoid neoplasms, see Table 113-1. ■ ■EPIDEMIOLOGY AND ETIOLOGY In 2023, it is estimated that there will be 80,550 new cases of NHL in the United States, ∼4% of all new cancers in both males and females, making it the seventh most common cause of cancer-related death in both women and men. The incidence is nearly 10 times the incidence TABLE 113-1  WHO-HAEM5 Classification of Lymphoid Malignancies B CELL T CELL Mature (peripheral) B-cell neoplasms Mature (peripheral) T-cell neoplasms   Lymphoplasmacytic lymphoma   T-cell granular lymphocytic leukemia (Waldenström’s macroglobulinemia)   Hairy cell leukemia   Splenic marginal zone B-cell   Adult T-cell leukemia/lymphoma (HTLV-1+)   Extranodal NK/T-cell lymphoma, lymphoma   Extranodal marginal zone B-cell nasal type   Enteropathy-associated T-cell lymphoma of MALT type   Nodal marginal zone B-cell lymphoma   Hepatosplenic T-cell lymphoma lymphoma   Follicular lymphoma   Mantle cell lymphoma   Diffuse large B-cell lymphoma   Subcutaneous panniculitis-like T-cell lymphoma   Mycosis fungoides   Sezary syndrome (including subtypes)   High-grade B-cell lymphoma with   Peripheral T-cell lymphoma NOS MYC and BCL2 rearrangements   High-grade B-cell lymphoma NOS   High-grade B-cell lymphoma with   Angioimmunoblastic T-cell lymphoma   Anaplastic large-cell lymphoma, ALK+ 11q aberrations   Burkitt’s lymphoma/Burkitt’s cell   Anaplastic large-cell lymphoma, ALK– leukemia   Primary mediastinal large B-cell lymphoma   Mediastinal grey zone lymphoma   Primary large B-cell lymphoma of immune-privileged sites   Plasmablastic lymphoma     Primary effusion lymphoma     HHV8+ DLBCL NOS     Intravascular large B-cell lymphoma     ALK+ large B-cell lymphoma   Abbreviations: DLBCL, diffuse large B-cell lymphoma; HHV, human herpesvirus; HTLV, human T-cell lymphotropic virus; MALT, mucosa-associated lymphoid tissue; NK, natural killer; NOS, not otherwise specified; WHO, World Health Organization. Source: Adapted from R Alaggio et al: The 5th edition of the World Health Organization classification of haematolymphoid tumours: Lymphoid neoplasms. Leukemia 36:1720, 2022. of HL. There is a slight male-to-female predominance and a higher incidence for Caucasians than for African Americans. The incidence rises steadily with age, especially after age 40, but lymphomas are also among the most common malignancies in adolescent and young adult patients. The incidence of NHL has nearly doubled over the past 20–40 years and continues to rise by 1.5–2% each year. Patients with both primary and secondary immunodeficiency states are predisposed to developing NHL. These include patients with HIV infection, patients who have undergone organ transplantation, and patients with inherited immune deficiencies and autoimmune conditions. The 5-year survival rate for NHL is 74% and is higher for Caucasians than it is for African Americans. The incidence of NHL and the patterns of expression of the various subtypes differ geographically and across age groups. T-cell lympho­ mas are more common in Asia than in Western countries, whereas certain subtypes of B-cell lymphomas such as follicular lymphoma (FL) are more common in Western countries. A specific subtype of NHL known as the angiocentric nasal T/NK-cell lymphoma has a striking geographic occurrence, being most frequent in southern Asia and parts of Latin America. Another subtype of NHL associated with infection by human T-cell lymphotropic virus (HTLV) 1 is seen particularly in southern Japan and the Caribbean (see Chap. 207). Likewise, there are differences in the age-dependent incidence of NHL by histologic subtype, with aggressive lymphomas like diffuse large B-cell lymphoma (DLBCL) and Burkitt’s lymphoma (BL) being the most common enti­ ties in children, and DLBCL and indolent lymphomas including FL being the most common forms in adults. The relative frequencies of the various types of lymphoid malignancies, including HL, plasma cell disorders, and lymphoid leukemias, are shown in Fig. 113-1. CHAPTER 113 Non-Hodgkin’s Lymphoma A number of environmental factors have been implicated in the occurrence of NHL, including infectious agents, chemical exposures, and medical treatments. Several studies have demonstrated an associa­ tion between exposure to agricultural chemicals and an increased inci­ dence of NHL. Patients treated for HL can develop NHL; it is unclear whether this is a consequence of the HL or its treatment, especially radiation. Several NHLs are associated with infectious agents (Table 113-2). Epstein-Barr virus (EBV) is associated with the development of BL in Central Africa and the occurrence of aggressive NHL in immuno­ suppressed patients in Western countries. The majority of primary central nervous system (CNS) lymphomas are associated with EBV. EBV infection is strongly associated with the occurrence of extrano­ dal nasal NK/T-cell lymphomas in Asia and South America. HTLV-1 infects T cells and leads directly to the development of adult T-cell lymphoma (ATL) in a small percentage of patients infected as babies through ingestion of breast milk of infected mothers. The median age of patients with ATL is ∼56 years; thus, HTLV-1 demonstrates a long latency from infection to oncogenesis (Chap. 207). Infection with HIV predisposes to the development of aggressive B-cell NHL. This may be through overexpression of interleukin 6 by infected macrophages. Infection of the stomach by the bacterium Helicobacter pylori induces the development of gastric mucosa-associated lymphoid tissue (MALT) lymphomas. This association is supported by evidence that patients treated with antibiotics to eradicate H. pylori have regression of their MALT lymphoma. The bacterium does not transform lymphocytes to produce the lymphoma; instead, a vigorous immune response is made to the bacterium, and the chronic antigenic stimulation leads to the neoplasia. MALT lymphomas of the skin may be related to Borrelia species infections in Europe, those of the eyes to Chlamydophila psit­ taci, and those of the small intestine to Campylobacter jejuni. Chronic hepatitis C virus infection has been associated with the development of lymphoplasmacytic lymphoma and splenic marginal zone lymphoma (MZL). Human herpesvirus 8 is associated with primary effusion lym­ phoma in HIV-infected persons and multicentric Castleman’s disease, a diffuse lymphadenopathy associated with systemic symptoms of fever, malaise, and weight loss. In addition to infectious agents, a number of other diseases or expo­ sures may predispose to developing lymphoma (Table 113-3). Diseases of inherited and acquired immunodeficiency as well as autoimmune Plasma cell disorders 16% CLL 9% Non-Hodgkin’s lymphoma 62.4% Hodgkin’s disease 8.2% ALL 3.8% PART 4 Oncology and Hematology FIGURE 113-1  Relative frequency of lymphoid malignancies. ALL, acute lymphoid leukemia; CLL, chronic lymphocytic leukemia; MALT, mucosa-associated lymphoid tissue. diseases are associated with an increased incidence of lymphoma. The association between immunosuppression and induction of NHLs is compelling because if the immunosuppression can be reversed, a percentage of these lymphomas regress spontaneously. The incidence of NHL is nearly a hundredfold increased for patients undergoing organ transplantation necessitating chronic immunosuppression and is greatest in the first year posttransplant. About 30% of these arise as a polyclonal B-cell proliferation that evolves into a clonal B-cell malignancy. The NHLs that occur in the context of immunosuppres­ sion or immunodeficiency, including HIV infection, are frequently associated with EBV. Histologically, DLBCLs are most frequently asso­ ciated with immunosuppression and autoimmune diseases, although almost all histologies can be seen, especially MALT lymphomas in the context of autoimmune diseases such as Sjögren’s syndrome and Hashimoto’s thyroiditis. The rare inherited immunodeficiency diseases X-linked lymphoproliferative syndrome, Wiskott-Aldrich syndrome, Chédiak-Higashi syndrome, ataxia-telangiectasia, and common vari­ able immunodeficiency syndrome are complicated by highly aggressive TABLE 113-2  Infectious Agents Associated with the Development of Lymphoid Malignancies INFECTIOUS AGENT LYMPHOID MALIGNANCY Epstein-Barr virus Burkitt’s lymphoma   Post–organ transplant lymphoma   Primary CNS diffuse large B-cell lymphoma   Hodgkin’s lymphoma   Extranodal NK/T-cell lymphoma, nasal type HTLV-1 Adult T-cell leukemia/lymphoma HIV Diffuse large B-cell lymphoma   Burkitt’s lymphoma Hepatitis C virus Lymphoplasmacytic lymphoma Helicobacter pylori Gastric MALT lymphoma Human herpesvirus 8 Primary effusion lymphoma   Multicentric Castleman’s disease Abbreviations: CNS, central nervous system; HIV, human immunodeficiency virus; HTLV, human T-cell lymphotropic virus; MALT, mucosa-associated lymphoid tissue; NK, natural killer. Non-Hodgkin’s lymphoma subtypes 31% Diffuse large B-cell lymphoma 22% Follicular lymphoma 7.6% MALT lymphoma 7.6% Mature T-cell lymphoma 6.7% Small lymphocytic lymphoma 6% Mantle cell lymphoma 2.4% Mediastinal large B-cell lymphoma 2.4% Anaplastic large-cell lymphoma 2.4% Burkitt’s lymphoma 1.8% Nodal marginal zone lymphoma 1.7% Precursor T-lymphoblastic lymphoma 1.2% Lymphoplasmacytic lymphoma 7.4% Others lymphomas. The elevated incidence of lymphoma in iatrogenic immu­ nosuppression, AIDS, and autoimmune disease argues strongly for immune dysregulation contributing to the pathogenesis of some lym­ phomas. An increased risk of NHL has been observed in first-degree relatives with NHL, HL, or chronic lymphocytic leukemia (CLL). In large database studies, ∼9% of patients with lymphoma or CLL have a first-degree relative with a lymphoproliferative disorder. ■ ■IMMUNOLOGY All lymphoid cells are derived from a common hematopoietic pro­ genitor that gives rise to lymphoid, myeloid, erythroid, monocyte, and megakaryocyte lineages. Through the ordered and sequential activa­ tion of a series of transcription factors, the cell first becomes commit­ ted to the lymphoid lineage and then gives rise to B and T cells. About 90% of all lymphomas are of B-cell origin. A cell becomes committed to B-cell development when it expresses the master B lin­ eage transcription factor PAX5, which ultimately results in a transcrip­ tional program that leads to the rearrangement of its immunoglobulin genes, which involves chromosomal recombination as well as somatic hypermutation to create an immunoglobulin gene that is unique to that B cell. The sequence of cellular changes, including changes in TABLE 113-3  Diseases or Exposures Associated with Increased Risk of Development of Malignant Lymphoma Inherited immunodeficiency disease   Klinefelter’s syndrome   Chédiak-Higashi syndrome   Ataxia-telangiectasia syndrome   Wiskott-Aldrich syndrome   Common variable immunodeficiency Autoimmune disease   Sjögren’s syndrome   Celiac sprue   Rheumatoid arthritis and systemic lupus erythematosus Chemical or drug exposures   Phenytoin   Dioxin, phenoxy herbicides   Radiation   Prior chemotherapy and radiation disease Acquired immunodeficiency diseases   Iatrogenic immunosuppression   HIV-1 infection   Acquired hypogammaglobulinemia therapy   Anti-TNF drugs Abbreviations: HIV, human immunodeficiency virus; TNF, tumor necrosis factor. Bone marrow Pre–B ALL Unclassified ALL TdT HCR κR or D TdT TdT HCR HCR λR or D H H HLA–DR+ CD19+ HLA–DR+ HLA–DR+ CD19+ CD19+ CD10+ CD10+ CD20+ CD22+ Lymphoid stem cell Early B cells Intermediate B cells Mature B cells Antigen-independent differentiation Antigen-driven differentiation FIGURE 113-2  Pathway of normal B-cell differentiation and relationship to B-cell lymphomas. HLA-DR, CD10, CD19, CD20, CD21, CD22, CD5, and CD38 are cell markers used to distinguish stages of development. Terminal transferase (TdT) is a cellular enzyme. Immunoglobulin heavy chain gene rearrangement (HCR) and light chain gene rearrangement or deletion (κR or D, λR or D) occur early in B-cell development. The approximate normal stage of differentiation associated with particular lymphomas is shown. ALL, acute lymphoid leukemia; CLL, chronic lymphocytic leukemia; SL, small lymphocytic lymphoma. cell-surface phenotype that characterizes normal B-cell development, is shown in Fig. 113-2. Most B-cell lymphomas arise following the process of immunoglobulin gene recombination and somatic hyper­ mutation, which leads to class switching and affinity maturation of the mature immunoglobulin, respectively, suggesting that it is the errorprone nature of these genetic events that contributes to oncogenesis. Certainly the frequency of chromosomal translocations that result in the activation of an oncogene or the inactivation of a tumor-suppressor gene in B-cell NHL may be the result of these normal cellular processes gone awry (see below). In addition, the key roles of the transcription factors MYC and BCL6 and the antiapoptotic protein BCL2 in the process of B-cell development explain why the genes encoding these proteins are commonly mutated in B-cell lymphomas. A cell becomes committed to T-cell differentiation upon migration to the thymus and rearrangement of T-cell receptor (TCR) genes. This requires the expression of the T-cell master regulatory transcription factor, NOTCH-1. As in B cells, the development of the mature TCR involves the rearrangement and recombination of the TCR loci, which is error-prone and potentially oncogenic. The sequence of the events that characterize T-cell development is depicted in Fig. 113-3. Although lymphoid malignancies often retain the cell-surface phenotype of lymphoid cells at particular stages of differentiation, this information is of little clinical or prognostic consequence. The so-called stage of differentiation of a malignant lymphoma does not predict its natural history. The antigen footprint, or immunopheno­ type, of the cell, however, is valuable diagnostically as it allows for the distinguishing of specific NHL subtypes. It can be detected by flow Follicular/diffuse IgM±IgG or IgG lymphomas Burkitt’s Lymphoid follicle HLA–DR+ IgM IgM IgM CD19+/− CD20+ IgD IgG CD22+/− CD21+/− Follicular center B cells Multiple myeloma HLA–DR+ HLA–DR+ HLA–DR+ Waldenström’s CD19+ CD19+ CD19+ IgM CD20+ CD20+ CD20+ CD22+ CD22+ CD22+ CD21+ CD21+ CD21+ Mantle cell lymphoma CLL SL CD19+/− CD38+ CD20+ PCA–1+ IgM±IgD IgM IgD CD38+ CHAPTER 113 Secretory B cells HLA–DR+ HLA–DR+ CD19+ CD19+ Non-Hodgkin’s Lymphoma CD10+/− CD20+ CD20+ CD22+/− CD22+ CD21+ CD21+ CD5+ CD5+ Mantle zone B cells cytometry of single-cell suspension from blood, bone marrow, body fluid, or disaggregated tissue using fluorescently labeled antibodies against these antigens or by immunohistochemical staining of paraffinembedded tissue sections with enzyme-linked antibodies against these antigens followed by a colorimetric reaction. As already mentioned, malignancies of lymphoid cells are associated with recurring genetic abnormalities including chromosomal translo­ cations and genetic mutations that may in part be the result of aberrant immunoglobulin or TCR development. While specific genetic abnor­ malities have not been identified for all subtypes of lymphoid malig­ nancies, it is presumed that they exist. As previously discussed, B cells are even more susceptible to acquiring mutations during their matura­ tion in germinal centers; the generation of antibody of higher affinity requires the introduction of mutations into the variable region genes in the germinal centers. Given this, other nonimmunoglobulin genes, e.g., bcl-6, may acquire mutations as well. Likewise, many lymphomas con­ tain balanced chromosomal translocations involving the antigen recep­ tor genes; immunoglobulin genes on chromosomes 2, 14, and 22 in B cells; and T-cell antigen receptor genes on chromosomes 7 and 14 in T cells. The rearrangement of chromosome segments to generate mature antigen receptors must create a site of vulnerability to aberrant recom­ bination. Examples of this type of event include the (8;14)(q24;q32) translocation in BL, involving the MYC proto-oncogene and the IgH gene; the (14;18)(q32;q32) translocation in FL, involving the BCL2 proto-oncogene and the IgH gene; and the (11;14) (q13;q32) translo­ cation in mantle cell lymphoma (MCL), involving the gene encoding cyclin D1 (CCDN1) and the IgH gene. Less commonly, chromosomal T-CELL DIFFERENTIATION T-CELL MALIGNANCIES THYMUS Stage I Prothymocyte Majority of T-cell ALL CD: 2, 7, 38, 71 Stage II Thymocyte Minority of T-ALL Majority of T-LL CD: 1, 2, 4, 7, 8, 38 Stage III Thymocyte Minority of T-LL Rare T-ALL CD: 2, 3, 4/8, 5, 6, 7; TCR PERIPHERAL BLOOD AND NODES Majority of T-CLL, CTCL, Sezary Cell, NHL Mature T Helper Cell CD: 2, 3, 4, 5, 6, 7; TCR PART 4 Oncology and Hematology Mature T Cytotoxic/ Suppressor Cell Minority of T-CLL, NHL CD: 2, 3, 5, 6, 7, 8; TCR FIGURE 113-3  Pathway of normal T-cell differentiation and relationship to T-cell lymphomas. CD1, CD2, CD3, CD4, CD5, CD6, CD7, CD8, CD38, and CD71 are cell markers used to distinguish stages of development. T-cell antigen receptors (TCR) rearrange in the thymus, and mature T cells emigrate to nodes and peripheral blood. ALL, acute lymphoid leukemia; CTCL, cutaneous T-cell lymphoma; NHL, nonHodgkin’s lymphoma; T-ALL, T-cell ALL; T-CLL, T-cell chronic lymphocytic leukemia; T-LL, T-cell lymphoblastic lymphoma. translocations produce fusion genes that encode chimeric oncogenic proteins. Examples of this include the (2;5)(p23;q35) translocation involving the ALK and NPM1 genes in anaplastic large-cell lymphoma (ALCL) and the t(11;18)(q21;q21) translocation involving the API2 and MLT genes in MALT lymphoma. Table 113-4 presents the most common translocations and associated oncogenes for various subtypes of lymphoid malignancies. Gene profiling using array technology allows the simultaneous assessment of the expression of thousands of genes. This technology provides the possibility to identify new genes with pathologic impor­ tance in lymphomas, the identification of patterns of gene expression with diagnostic and/or prognostic significance, and the identification of new therapeutic targets. Recognition of patterns of gene expression is complicated and requires sophisticated mathematical techniques. Early successes using this technology in lymphoma include the iden­ tification of previously unrecognized subtypes of DLBCL whose gene expression patterns resemble either those of follicular or germinal cen­ ter B (GCB) cells or activated peripheral blood B cells (ABC). Patients whose lymphomas have a GCB-like pattern of gene expression have a considerably better prognosis than those whose lymphomas have a pattern resembling ABCs. This improved prognosis is independent of other known prognostic factors. These subcategories have been more specifically refined into five subcategories, using more advanced genetic sequencing techniques, that differ with respect to biology and driver genes, as well as prognosis, and may have important treatment implications in the future. Similar information is being generated in FL and MCL. The challenge remains to provide information from such techniques in a clinically useful time frame. APPROACH TO THE PATIENT Regardless of the type of lymphoid malignancy, the initial evalua­ tion of the patient should include performance of a careful history and physical examination. These will help confirm the diagnosis, TABLE 113-4  Genetic Features of B- and T-Cell Lymphomas GENETIC FEATURE GENES LYMPHOMA t(8;14) t(2;8) t(8;22) MYC/IgH MYC/Igκ MYC/Ig λ Burkitt’s lymphoma t(11;14) BCL1 (CCND1)/IgH Mantle cell lymphoma; multiple myeloma t(14;18) t(3;14) BCL2/IgH BCL6/IgH Follicular lymphoma, diffuse large B-cell lymphoma (DLBCL) t(11;18) t(1;14) t(14;18) t(3;14) API2/MALT1 BCL10/IgH MALT1/IgH FOXP1/IgH MALT lymphoma Trisomy 3 7q21 deletion Unknown CDK6 Splenic marginal zone lymphoma t(9;14) 6q21 deletion PAX5/IgH Unknown Lymphoplasmacytic lymphoma inv(14) t(14;14) TCRα/TCL1 Peripheral T-cell lymphoma, NOS; T-PLL t(2;5) t(1;2) t(2;3) t(2;17) inv(2) NPM1/ALK TPM3/ALK TFG/ALK CTLC/ALK ATIC/ALK Anaplastic large-cell lymphoma (ALCL) Trisomy 3 Trisomy 5 Unknown Unknown Angioimmunoblastic T-cell lymphoma Isochromosome 7q Unknown Hepatosplenic T-cell lymphoma Abbreviations: MALT, mucosa-associated lymphoid tissue; NOS, not otherwise specified; T-PLL, T-cell prolymphocytic leukemia. identify those manifestations of the disease that might require prompt attention, and aid in the selection of further studies to optimally characterize the patient’s status to allow the best choice of therapy. It is difficult to overemphasize the importance of a care­ fully done history and physical examination. They might provide observations that lead to reconsidering the diagnosis, provide hints at etiology, clarify the stage, and allow the physician to establish rap­ port with the patient that will make it possible to develop and carry out a therapeutic plan. The duration of symptoms and pace of symptomatic progres­ sion are important in distinguishing aggressive from more indo­ lent lymphomas, as are the presence or absence of “B” symptoms, such as fevers, night sweats, or unexplained weight loss. Patients should be asked about localizing symptoms that may point toward lymphomatous involvement of specific sites, such as the chest, abdomen, or CNS. Comorbid diagnoses that may impact therapy or monitoring on therapy should be reviewed and acknowledged, including a history of diabetes or congestive heart failure. A physi­ cal examination should pay close attention to all the peripherally accessible sites of lymph nodes; the liver and spleen size; Waldeyer’s ring; whether there is a pleural or pericardial effusion or abdominal ascites; whether there is an abdominal, testicular, or breast mass; and whether there is cutaneous involvement because all of these findings may influence further evaluation and disease management. Laboratory studies should include a complete blood count, routine chemistries, liver function tests, and serum protein elec­ trophoresis to document the presence of circulating monoclonal paraproteins. The serum β2-microglobulin level and serum lactate dehydrogenase (LDH) are important independent prognostic fac­ tors in NHL. Staging of certain diseases may involve a bone mar­ row biopsy; results of other laboratory and staging studies may also warrant a marrow evaluation. A lumbar puncture for evaluation of lymphomatous involvement may be indicated in the setting of concerning neurologic signs or symptoms or diseases that are high risk for CNS involvement. The latter may include disease involv­ ing the paranasal sinuses, testes, breast, kidneys, adrenal glands, and epidural space, as well as highly aggressive histologies like BL. Since HIV and hepatitis B and C infection can be risk factors for developing NHL, and since treatment for some NHLs can result in the potentially life-threatening reactivation of hepatitis B, patients with a new diagnosis of NHL should be screened for these viruses as well. Lymphoma histology and clinical presentation dictate which imaging studies should be ordered. Chest, abdominal, and pelvic computed tomography (CT) scans are essential for accurate stag­ ing to assess lymphadenopathy for indolent lymphomas, whereas positron emission tomography (PET) using 18F-fluorodeoxyglucose (FDG-PET) is useful for aggressive lymphomas, including BL, DLBCL, plasmablastic lymphoma, and the aggressive T-cell NHLs. FDG-PET is highly sensitive for detecting both nodal and extra­ nodal sites involved by NHL. The intensity of FDG avidity, or standardized uptake value (SUV), correlates with histologic aggres­ siveness, and may be useful in cases when disease transformation of an indolent lymphoma to a diffuse aggressive lymphoma is sus­ pected. PET scanning can also differentiate between treated disease and active disease at the end of therapy in patients with residual masses on CT scans. Consensus recommendations regarding PET scanning were published as a result of an International Harmoniza­ tion Project and state that PET should only be used for DLBCL and HL, that scanning during therapy should only be done as part of clinical trials, and that the end-of-treatment scan should not be done before 3 weeks but preferably 6–8 weeks after chemotherapy and 8–12 weeks after radiation or chemoradiotherapy. There is no evidence that long-term follow-up should include PET scanning. More recently, though, PET scan results at the end of therapy for FL have been associated with prognosis, with patients with residual PET-avid disease at the end of treatment having a poorer prognosis than those who are PET negative, and so it may be used for this prognostic purpose. Finally, magnetic resonance imaging (MRI) is useful in detecting bone, bone marrow, and CNS disease in the brain and spinal cord. The staging evaluation is outlined in Table 113-5. The Ann Arbor staging system developed in 1971 for HL was adapted for staging NHLs (Table 113-6). This staging system focuses on the number of tumor sites (nodal and extranodal), location, and the presence or absence of systemic, or B, symptoms. Table 113-6 summarizes the essential features of the Ann Arbor system. This anatomic based system is less useful in NHL, which dis­ seminates widely, not in an ordered stepwise fashion. A majority of patients with NHL have advanced-stage disease at diagnosis. Apart TABLE 113-5  Staging Evaluation for Non-Hodgkin’s Lymphoma Physical examination Documentation of B symptoms Laboratory evaluation   Complete blood counts   Liver function tests   Uric acid   Calcium   Serum protein electrophoresis   Serum β2-microglobulin Chest radiograph CT scan of abdomen, pelvis, and usually chest Bone marrow biopsy Lumbar puncture in lymphoblastic, Burkitt’s, and diffuse large B-cell lymphoma with positive marrow biopsy Gallium scan (SPECT) or PET scan in large-cell lymphoma Abbreviations: CT, computed tomography; PET, positron emission tomography; SPECT, single-photon emission computed tomography. TABLE 113-6  Ann Arbor Staging for Lymphomaa STAGE DESCRIPTION I Involvement of a single lymph node region (I) or single extranodal site (IE) II Involvement of two or more lymph node regions or lymphatic structures on the same side of the diaphragm alone (II) or with involvement of limited, contiguous, extralymphatic organ or tissue (IIE) III Involvement of lymph node regions on both sides of the diaphragm (III), which may include the spleen (IIIS), or limited, contiguous, extralymphatic organ or tissue (IIIE), or both (IIIES) IV Diffuse or disseminated foci of involvement of one or more extralymphatic organs or tissues, with or without associated lymphatic involvement aAll stages are further subdivided according to the absence (A) or presence (B) of systemic B symptoms including fevers, night sweats, and/or weight loss (>10% of body weight over 6 months prior to diagnosis). from early-stage disease limited to a radiation field where local therapy with radiation is an option, all other disease is treated the same regardless of stage. Histology and clinical parameters at pre­ sentation are more important than stage with respect to prognosis. The International Prognostic Index (IPI) is perhaps the best predic­ tor of outcome (Table 113-7). The IPI was developed based on the analysis of >2000 patients with aggressive NHLs treated with an anthracycline-containing regimen. Age (≤60 vs >60), serum LDH (≤ normal vs > normal), performance status (0 or 1 vs 2–4), stage (I or II vs III or IV), and extranodal involvement (<1 site vs >1 site) were identified as independently prognostic for overall survival (OS). A point is awarded for each risk factor and then summed, defining four risk groups: low (0 or 1); low-intermediate (2); highintermediate (3); and high (4–5). The 5-year OS rates for patients with scores of 0–1, 2, 3, and 4–5 were 73, 51, 43, and 26%, respec­ tively. The age-adjusted IPI separates patients ≤60 from patients >60. For the age-adjusted IPI, only stage, LDH, and performance status were important. Younger patients with 0, 1, 2, or 3 risk factors had 5-year survival rates of 83, 69, 46, and 32%, compared to 56, 44, 37, and 21% for older patients. When factoring in the introduction and clinical benefit of rituximab, the 4-year progression-free sur­ vival rates are 94, 80, and 53% for 0–1, 2, or 3 or more risk factors, respectively. CHAPTER 113 Non-Hodgkin’s Lymphoma The Follicular Lymphoma International Prognostic Index (FLIPI) is a similar predictive model for FL, derived from the analysis of >4000 patients. Age >60, stage III/IV disease, the TABLE 113-7  International Prognostic Index for NHL Five Clinical Risk Factors Age ≥60 years Serum lactate dehydrogenase levels elevated Performance status ≥2 (ECOG) or ≤70 (Karnofsky) Ann Arbor stage III or IV >1 site of extranodal involvement For Diffuse Large B-Cell Lymphoma 0, 1 factor = low risk 35% of cases; 5-year survival, 73% 2 factors = low-intermediate risk 27% of cases; 5-year survival, 51% 3 factors = high-intermediate risk 22% of cases; 5-year survival, 43% 4, 5 factors = high risk 16% of cases; 5-year survival, 26% For Diffuse Large B-Cell Lymphoma Treated With R-CHOP 0 factor = good 10% of cases; 4-year survival, 94% 1, 2 factors = intermediate 45% of cases; 4-year survival, 80% 3, 4, 5 factors = poor 45% of cases; 4-year survival, 53% Abbreviations: ECOG, Eastern Cooperative Oncology Group; NHL, non-Hodgkin’s lymphoma; R-CHOP, rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone. presence of >4 nodal sites, an elevated serum LDH concentration, and a hemoglobin <12 were identified as independent prognostic variables, and summation of each variable identified three risk groups. The median 10-year survival rates for patients with zero to one (low risk), two (intermediate risk), or three or more (high risk) of these adverse factors were 71, 51, and 36%, respectively. Similar disease-specific IPIs have been developed for MCL and periph­ eral T-cell lymphoma (PTCL) as well. These prognostic indices take into account the proliferative index and cell-surface markers, respectively. Finally, as mentioned previously, gene expression profiling has identified DLBCLs with differential prognoses: GCB and ABC, where GCB-like DLBCL is associated with a significantly better OS. A more readily accessible immunohistochemical algorithm has been developed, based on the presence or absence of CD10, BCL6, and MUM1, that correlates closely with gene expression profiles and can differentiate the majority of GCB from non–GCB-like DLBCL. These profiles have prognostic importance but, to date, do not alter treatment recommendations for the primary treatment of DLBCL. Current clinical trials do stratify by DLBCL subtype, and it appears that agents like the Bruton tyrosine kinase (BTK) inhibitor ibrutinib and lenalidomide are most active in non-GCB DLBCL in the relapsed setting. Treatment may then be differentiated by these subtypes in the future. PART 4 Oncology and Hematology CLINICAL FEATURES, TREATMENT, AND PROGNOSIS OF SPECIFIC NHL ■ ■MATURE B-CELL NEOPLASMS B-cell NHLs can be characterized into two broad groups—those that behave aggressively, require immediate or urgent treatment with combination chemotherapy regimens, and are potentially curable; and those that are more indolent in nature, can be observed and treated only when they cause symptoms or signs of organ function impair­ ment, are very responsive to therapy, but are not ultimately curable in the vast majority of cases. Among the aggressive diseases, the most common is DLBCL, and the most rapidly growing is BL. FL is the sec­ ond most common NHL and the most common indolent NHL. Other indolent NHLs include MZL, lymphoplasmacytic lymphoma (LPL), and hairy cell leukemia (HCL). MCL is an intermediate-grade lym­ phoma that shares some characteristics with the aggressive lymphomas (fairly urgent need for treatment and aggressive upfront combination chemotherapy regimens), but like the indolent lymphomas, it is not readily curable with conventional-dose therapies. Burkitt’s Lymphoma  Burkitt’s lymphoma/leukemia (BL) is a rare disease in adults in the United States, making up <1% of NHL, but it makes up ∼30% of childhood NHL. It is one of the fastest growing neo­ plasms, with a doubling time of <24 h. In general, it is a pediatric tumor that has three major clinical presentations. The endemic (African) form presents as a jaw or facial bone tumor that spreads to extranodal sites including ovary, testis, kidney, breast, and especially the bone marrow and meninges. The nonendemic form has an abdominal presentation with massive disease, ascites, and renal, testis, and/or ovarian involve­ ment and, like the endemic form, also spreads to the bone marrow and CNS. Immunodeficiency-related cases more often involve lymph nodes and may present as acute leukemia. BL has a male predominance and is typically seen in patients <35 years of age. On biopsy, there is a monotonous infiltration of medium-sized cells with round nuclei, multiple nucleoli, and basophilic cytoplasm with vacuoles. The proliferation rate is ∼100%, and tingible body macro­ phages give rise to the classic “starry sky” appearance of this tumor (Fig. 113-4). Tumor cells are positive for B-cell antigens CD19 and CD20 and surface immunoglobulin. They are also uniformly positive for CD10 and BCL6 but negative for BCL2. Endemic BLs are EBV posi­ tive, whereas the majority of nonendemic BLs are EBV negative. BL is associated with a translocation involving MYC on chromosome 8q24 in >95% of the cases. The most common partners are chromosomes 14, FIGURE 113-4  Burkitt’s lymphoma. The neoplastic cells are homogeneous, mediumsized B cells with frequent mitotic figures, a morphologic correlate of high growth fraction. Reactive macrophages are scattered through the tumor, and their pale cytoplasm in a background of blue-staining tumor cells gives the tumor a so-called starry sky appearance. 2, or 22, rearrangements that produce fusions of MYC with either the IgH (80%), kappa (15%), or lambda (5%) light chain genes, respectively. While exquisitely chemosensitive, it is imperative that treatment for BL be initiated quickly given the rapid doubling time and high morbidity of this disease. There are several effective intensive combi­ nation chemotherapy regimens, all of which incorporate high doses of cyclophosphamide. Prophylactic therapy to the CNS is mandatory. Cure can be expected in 80–90% of patients when treated promptly and correctly. Modified Magrath and dose-adjusted EPOCH-R (ritux­ imab, infusional etoposide/vincristine/doxorubicin, cyclophospha­ mide, prednisone) are highly effective regimens. Salvage therapy has been generally ineffective in patients whose disease progresses after upfront therapy, emphasizing the importance of the initial treatment approach and referral to a tertiary cancer center with experience treat­ ing this disease. Diffuse Large B-Cell Lymphoma  DLBCL is the most common histologic subtype of NHL diagnosed, representing about one-third of all cases. Previously felt to be “one disease,” it is now recognized as a heterogeneous collection of multiple entities. It is slightly more com­ mon in Caucasians and men, and the median age at diagnosis is 64. The relative risk (RR) of DLBCL is higher among people with affected first-degree relatives (RR 3.5-fold), and patients with congenital or acquired immunodeficiency, patients on immunosuppression, and patients with autoimmune disorders also have a higher risk of develop­ ing DLBCL, often EBV-related. The majority of patients present with advanced-stage disease, with only 30–40% of patients having stage I or II disease; ∼40% of patients will have “B” symptoms, and 50% of patients will have an elevated LDH. Up to 40% of patients will have involvement of non–lymph node sites including bone marrow, CNS, gastrointestinal tract, thyroid, liver, and skin. Patients with extensive bone marrow involvement or involvement of the testes, breast, kidney, adrenal gland, paranasal sinus, or epidural space are at increased risk of CNS dissemination. The tumor consists of a diffuse proliferation of large, atypical lym­ phocytes with a high proliferative index (Fig. 113-5). These cells typi­ cally express the B-cell antigens CD19, CD20, and CD79a. Expression of CD10 and BCL6 is consistent with the tumor cell being of germinal center origin (GCB), while the expression of MUM1 corresponds with the non–germinal center or ABC subtype. BCL2 is overexpressed in anywhere from 25 to 80% of DLBCLs, whereas BCL6 is positive in more than two-thirds of cases, as the result of translocations, gain of copy number, or promoter mutations. MYC is rearranged in 10% of DLBCLs, and ∼20% of MYC-rearranged cases have a concurrent BCL2 rearrangement, a combination referred to as “double-hit lymphoma.” These double-hit lymphomas constitute one subtype of high-grade B-cell lymphoma (HGBL) and are associated with an extremely poor FIGURE 113-5  Diffuse large B-cell lymphoma. The neoplastic cells are heterogeneous but predominantly large cells with vesicular chromatin and prominent nucleoli. prognosis with a median OS of only 12–18 months. The other subtype of HGBL is called HGBL not otherwise specified (NOS) and is defined based on blastoid or Burkitt-like morphologic features. Amplification and/or overexpression of MYC independent of rearrangements or amplification have also been described and are also associated with a poor, albeit better, prognosis. Combination chemotherapy offers potentially curative therapy for DLBCL, regardless of the stage. The addition of the anti-CD20 antibody rituximab to cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) improved survival beyond CHOP alone and has been the standard first-line chemotherapy for this disease for decades. The combination of R-CHP (R-CHOP without vincristine) and the antibody-drug conjugate (ADC) polatuzumab was compared to R-CHOP in the randomized POLARIX study and demonstrated a progression-free survival benefit with polatuzumab–R-CHP, leading to the approval of this regimen as a new standard option for patients with IPI 2 or higher disease. For patients with early-stage disease localized to a radiation field, treatment options include full-course chemotherapy with R-CHOP every 3 weeks for six cycles or abbreviated chemo­ therapy for three to four cycles followed by involved field radiotherapy. The randomized FLYER studies compared four versus six cycles of R-CHOP chemotherapy for early favorable-risk DLBCL and showed no benefit to a more extended course of chemotherapy. For advancedstage DLBCL, therapy is with a full course of chemotherapy. On aver­ age, ∼65–70% of patients with DLBCL can be expected to be cured with this approach, and the likelihood of cure is predicted by the IPI, gene expression profile cell of origin, and/or MYC cytogenetics and expres­ sion. Several studies, other than the above mentioned POLARIX study, have investigated alternative anthracycline-containing chemotherapy regimens and/or consolidation autologous stem cell transplanta­ tion in first remission for higher-risk disease without improvement over R-CHOP alone. Dose-adjusted R-EPOCH is one such regimen. Although this regimen did not appear to be better than R-CHOP for DLBCL in one multicenter clinical trial, it is often used to treat primary mediastinal large B-cell lymphoma and double-hit DLBCL based on results from phase 2 and retrospective studies, respectively. CNS pro­ phylaxis with either intrathecal chemotherapy or high-dose systemic methotrexate and leucovorin rescue offers unclear benefit to patients at high risk for CNS relapse and is increasingly not being used based on results of retrospective and observational studies. Over one-third of patients will either have primary refractory disease or disease that relapses after first-line chemotherapy. These patients may still be cured with either salvage chemotherapy regimens followed by autologous stem cell transplantation (for patients relaps­ ing >12 months from the completion of therapy) or CD19 chimeric antigen receptor (CAR) T cells (for patients with primary refractory or early relapsing disease or those who are not felt to be autologous stem cell transplantation candidates). However, patients with a poor performance status or certain comorbid conditions who are not can­ didates for such approaches are often managed with palliative inten­ tions. Radiation to symptomatic areas of disease can be transiently helpful. Less intensive chemotherapy with drugs such as gemcitabine, cytarabine, or bendamustine can help control disease and symptoms for a limited period of time. Newer drugs including the CD79b ADC polatuzumab in combination with bendamustine and rituximab (BR), the high-affinity CD19 monoclonal antibody (mAb) tafasitamab in combination with lenalidomide, the CD19 ADC loncastuximab, and the CD20-CD3 bispecific antibodies epcoritamab and glofitamab have been approved for use in these palliative settings as well as for patients who relapse after CAR-T therapy or autologous stem cell transplanta­ tion. Some of these agents can be used as a bridge to a definitive allo­ geneic stem cell transplantation For patients in whom more aggressive therapy is an option, treatment for late relapsing patients is with combination chemotherapy using vari­ ous combinations of drugs primarily in order to identify patients with chemosensitive disease. Patients with chemosensitive disease have the greatest likelihood of benefiting from high-dose chemotherapy and autologous stem cell transplant, which improves response duration and survival over salvage chemotherapy alone and leads to long-term disease-free survival in ∼40–50% of patients. The randomized ZUMA-7 and TRANSFORM studies of the CD19 CAR-T therapies axicabtagene ciloleucel (axi-cel) and lisocabtagene autoleucel (liso-cel) established both of these CAR-T therapies as the most effective option for patients with primary refractory or early (<12 months) relapsing disease over salvage chemotherapy and autologous stem cell transplantation. CHAPTER 113 For this therapy, T cells are collected from a patient and are then genetically modified to express a receptor that will bind to a surface antigen expressed on the patient’s own tumor cells. In the case of B-cell malignancies, CD19 has been targeted most commonly. After infu­ sion, autologous CAR-T cells home to sites of disease and persist over time. The CARs consist of an extracellular antigen recognition domain (typically a single-chain Fv variable fragment from a monoclonal anti­ body) linked via a transmembrane domain to an intracellular signaling domain (usually the CD3ζ endodomain), resulting in the redirection of T-cell specificity toward target antigen-positive cells, and one or more costimulatory domains including CD28, 4-1BB, or OX40 to enhance cytokine secretion and effector cell expansion and prevent activationinduced apoptosis and immune suppression by tumor-related metabo­ lites. For late relapsing patients with chemorefractory disease, CAR-T therapies such as axi-cel, liso-cel, and tisagenlecleucel (tisa-cel) offer a potentially curative option in the third-line setting as well. In this set­ ting, the response rate of CAR-T cells is >80%, with >50% of patients achieving a complete response. These responses appear to be durable, with 40% of patients in remission at long-term follow-up. Non-Hodgkin’s Lymphoma Other large B-cell lymphomas include intravascular large B-cell lymphoma, T-cell/histiocyte–rich large B-cell lymphoma, EBV-positive DLBCL of the elderly, and ALK-positive large B-cell lymphoma. Patients with the latter two diseases tend to have a poor progno­ sis, whereas the addition of rituximab to CHOP chemotherapy has dramatically improved outcomes with intravascular large B-cell lymphoma, and the outcomes in T-cell/histiocyte–rich large B-cell lymphoma are similar to DLBCL. R-CHOP remains the treatment of choice for each of these lymphomas. Follicular Lymphoma  FLs are the second leading NHL diagnosis in the United States and Europe and make up 22% of NHLs worldwide and at least 30% of NHLs diagnosed in the United States. This type of lymphoma can be diagnosed accurately on morphologic findings alone and has been the diagnosis in the majority of patients in therapeutic trials for “low-grade” lymphoma in the past. Evaluation of an adequate biopsy by an expert hematopathologist is sufficient to make a diagnosis of FL. The tumor is composed of small cleaved and large cells in varying proportions organized in a follicular pattern of growth (Fig. 113-6). Confirmation of B-cell immunopheno­ type (monoclonal immunoglobulin light chain, CD19, CD20, CD10, and BCL6 positive, and CD5 and CD23 negative) and the existence of t(14;18) and abnormal expression of BCL2 protein are confirmatory. FIGURE 113-6  Follicular lymphoma. The normal nodal architecture is effaced by nodular expansions of tumor cells. Nodules vary in size and contain predominantly small lymphocytes with cleaved nuclei along with variable numbers of larger cells with vesicular chromatin and prominent nucleoli. While >85% of FLs will harbor a t(14;18) and overexpress the anti­ apoptotic protein BCL2, this genetic event is necessary but not suffi­ cient for malignant transformation of the B lymphocytes, and multiple genetic events are required for the development of FL. Studies have identified the most common recurrent genetic events in FL, and they included mutations in several epigenetic modifying genes, including MLL2, EZH2, CREBBP, and EP300. The major differential diagnosis is between lymphoma and reactive follicular hyperplasia. The coexistence of DLBCL must be considered. Patients with FL are often subclassi­ fied, or graded, into those with predominantly small cells, those with a mixture of small and large cells, and those with predominantly large cells. The WHO classification adopted grading from I to III based on the number of centroblasts, or large cells, counted per high-power field (hpf): grade I, from 0 to 5 centroblasts/hpf; grade II, from 6 to 15 centroblasts/hpf; and grade III, >15 centroblasts/hpf. Grade III has been subdivided into grade IIIa, in which centrocytes predominate, and follicular large B-cell lymphoma (FLBCL), in which there are sheets of centroblasts. While this distinction cannot be made simply or very reproducibly, these subdivisions do have prognostic significance. Patients with FL with predominantly large cells have a higher prolifera­ tive fraction, progress more rapidly, and have a shorter OS with simple chemotherapy regimens. FLBCL is an aggressive disease and consid­ ered most similar to DLBCL and treated as such with curative intent. PART 4 Oncology and Hematology The most common presentation for FL is with new, painless lymph­ adenopathy. Multiple sites of lymphoid involvement are typical, and unusual sites such as epitrochlear nodes are sometimes seen. However, essentially any organ can be involved, and extranodal presentations do occur. Most patients do not have an elevated LDH or fevers, night sweats, or weight loss, although histologic transformation to DLBCL does occur at a rate of ∼3% per year and can be associated with these signs or symptoms. As discussed previously, prognosis is best predicted by the FLIPI. Staging is typically done with CT scans of the chest, abdomen, and pelvis, as well as the neck if neck disease is suspected, although PET/CT scans can be helpful in cases where disease trans­ formation is suspected, as transformed disease will be more FDG avid than indolent disease, or for confirmation of early-stage disease, where definitive local therapy with radiation may be considered. Although FL is highly sensitive to chemotherapy and radiotherapy, these therapies are usually not ultimately curative, except in the setting of early-stage disease. If the disease can be encompassed in a radiation field, involved field radiotherapy at a dose of 24–30 Gy may be cura­ tive, with 5-, 10-, and 15-year freedom from treatment failure rates of 72, 46, and 39%, and overall 5-, 10-, and 15-year survival rates of 93, 75, and 62%, respectively. If radiation therapy would not be toler­ ated or if a patient prefers not to receive radiation, observation is a reasonable alternative with a median time to treatment not reached at 7 years of follow-up in one study. Many of these patients are diagnosed incidentally or at a time when their lymphoma is not causing symp­ toms or signs of organ function impairment. Numerous studies have shown that treating patients with asymptomatic disease does not improve survival compared with a program of close observation, with treatment reserved for symptomatic disease progression or organ dys­ function. Thus, asymptomatic patients should be observed. When systemic treatment is indicated, a variety of treatment options are available, including the use of the monoclonal antibody against CD20, rituximab, alone or in combination with chemotherapy or with the oral drug lenalidomide. Treatment decisions are often determined by the indication for treatment and/or by the volume of disease being treated. For patients requiring therapy for inflamma­ tory or autoimmune phenomenon thought to be driven by FL or for patients with low-volume disease, single-agent rituximab is associ­ ated with a response rate of ∼70% and a median response duration of >2 years. This response duration is improved with the addition of main­ tenance rituximab following a favorable response to rituximab induc­ tion therapy. For patients with a larger volume of disease at the time of treatment initiation, the addition of rituximab (R) to chemotherapy regimens such as CHOP or cyclophosphamide, vincristine, and pred­ nisone (CVP) has improved survival in this disease. The combination of bendamustine and rituximab (BR) has been compared to R-CHOP and results in longer response duration and less toxicity. Thus, BR has become the standard of care for the first-line therapy of medium- to high-volume FL. Similarly, the addition of maintenance rituximab following a good response to R-CHOP or R-CVP improves response duration when used in newly treated FL patients. A newer anti-CD20 antibody, obinutuzumab, has been tested in combination with chemo­ therapy in a randomized trial against rituximab plus chemotherapy in previously untreated FL. The obinutuzumab combinations resulted in improvements in minimal residual disease (MRD) negativity as well as progression-free survival at the expense of more infection and infusion reactions. Based on these results, both rituximab plus chemotherapy and obinutuzumab plus chemotherapy are options for untreated FL in need of treatment. The superiority of one over the other has not been established. Finally, a randomized study has compared rituximab plus chemotherapy with either BR, R-CHOP, or R-CVP to rituximab plus lenalidomide, and results were similar in both arms, thus making the chemotherapy-free rituximab-lenalidomide regimen an option for the frontline treatment of FL. In patients with FL, the disease nearly always recurs following therapy, after which retreatment is again reserved for symptomatic disease or disease interfering with organ function. Single-agent ritux­ imab or alternative chemotherapy regimens, with both rituximab and obinutuzumab, can again be employed. Both autologous and allogeneic hematopoietic stem cell transplantations yield high complete response rates in patients with relapsed FL, and long-term remissions can occur in 40 and 60% of patients, respectively. The latter is associated with con­ siderable treatment-related morbidity and mortality and so is usually reserved for patients with multiply relapsed FL that is no longer respon­ sive to chemotherapy. More targeted oral therapies like lenalidomide and the EZH2 inhibitor tazemetostat are active in relapsed FL. The PI3 kinase inhibitors idelalisib, duvelisib, and copanlisib are active in FL but are no longer available given the lack of randomized confirmatory evidence to support their efficacy. The anti-CD19–directed CAR-T therapies axi-cel and tisa-cel have been approved for relapsed FL in the third-line setting and beyond, with complete responses seen in >80% of patients with multiply relapsed disease, and with many of those responses proving durable, albeit with limited follow-up. Longer followup is needed to determine if this may be a definitive treatment strategy for a subset of relapsed FL patients. The CD20-CD3 bispecific antibody mosunetuzumab has been approved for FL in the third-line setting and beyond as well and offers a highly effective and potentially less toxic option for patients compared with CAR-T therapy. On average, most patients will live with FL for 15–20 years, a number that is increasing given our improved understanding of the genetics and microenviron­ ment of FL and the increasing number of drugs and therapies being tested in this disease. However, in addition to a high-risk FLIPI, patients who do not have a complete metabolic response by PET/CT scanning to their primary therapy and patients who relapse within 2 years of the completion of their primary chemotherapy tend to do poorly with chemotherapy and should be considered for some of these non­ chemotherapy options. Randomized trials comparing chemotherapy, lenalidomide-based therapy, and CAR-T therapy in the second-line set­ ting for these refractory or early relapsing patients are underway. Patients with FL have a high rate of histologic transformation to DLBCL (∼3% per year). This is recognized ∼40% of the time during the course of the illness by repeat biopsy and is present in almost all patients at autopsy. This transformation is usually heralded by rapid growth of lymph nodes—often localized—and the development of systemic symptoms such as fevers, sweats, and weight loss. When this happens in patients who have had previously untreated FL, treatment with R-CHOP chemotherapy, as for DLBCL, can be curative for the aggressive component while the FL may eventually recur. In patients with previously treated FL that transforms to DLBCL, prognosis is poor, and successful therapy with an aggressive combination chemo­ therapy regimen should be consolidated with an autologous stem cell transplant. CAR-T therapy and other therapies for relapsed/refractory DLBCL are options for chemorefractory transformations. Finally, as discussed previously, grade IIIb FL is more similar to DLBCL than it is to FL and should be treated as such. Marginal Zone Lymphoma  The second most common indolent B-cell NHL is MZL. There are three main types: splenic MZL, extrano­ dal MZL of MALT, and nodal MZL. Nodal MZL most closely resembles FL clinically, and much of the way we manage and treat it is based on studies done in FL. Tumor biopsies in this disease show parafollicular and perivascular infiltration by monocytoid-appearing atypical lymphocytes with folded nuclear contours that are positive for CD19, CD20, and CD79a but negative for CD10 and largely negative for CD5. Some cases can have plasmacytoid differentiation and can be associated with a monoclonal expression of kappa or lambda light chains and with small monoclonal immunoglob­ ulin spikes. Treatment is often similar to that of FL, with the exception that the BTK inhibitors ibrutinib and zanubrutinib are highly active in this disease, while largely disappointing in FL, and are good treatment options for relapsed nodal MZL as well as other MZL subtypes. CAR-T therapy is not approved in MZL but has been tested in clinical trials with similar efficacy to what has been shown in FL. Splenic MZL is largely a disease of older Caucasian patients; infec­ tion with hepatitis C is a risk factor for this disease, and treatment of hepatitis C can result in regression of the lymphoma. Patients present with a lymphocytosis with or without cytopenias and splenomegaly. Bone marrow involvement is common. Diagnosis can be made by flow cytometry of the peripheral blood; malignant lymphocytes will be positive for surface immunoglobulin, CD19, and CD20 and will generally lack CD5 and CD10. On peripheral smear, they have small nuclei and abundant cytoplasm with “shaggy” or villous projections. It can be differentiated from HCL by the absence of CD25, CD103, and annexin A1. Recurrent cytogenetic abnormalities include trisomy 3 and abnormalities of chromosome 7q. Therapy is indicated for symp­ tomatic disease or significant cytopenias. Splenectomy is reasonable for selected patients with excellent relief of symptoms and cytopenias. Splenectomy is associated with an overall response rate of 85% and estimated progression-free survival and OS rates at 5 years of 58 and 77%, respectively. Single-agent rituximab can improve splenomegaly and cytopenias in >90% of patients. In a study of induction with weekly rituximab followed by maintenance, the response rate was 95%, with OS and progression-free survival rates at 5 years of 92 and 73%, respectively. Other options for therapy at relapse are similar to those used for FL and include retreatment with rituximab, alkylating agents, and purine analogues in combination with rituximab. The survival rate of patients is in excess of 70% at 10 years. MALT lymphoma is an MZL lymphoma of extranodal tissue, most commonly the stomach, but other common sites include the skin, sali­ vary glands, lung, small bowel, ocular adnexa, breasts, bladder, thyroid, dura, and synovium. It is associated with states of chronic inflamma­ tion due to either autoimmune diseases like Sjögren’s syndrome or Hashimoto’s thyroiditis or chronic infections with organisms such as H. pylori (gastric), Borrelia burgdorferi (skin), C. psittaci (conjunctiva), C. jejuni (intestines), and hepatitis C virus. The essential pathologic feature of MALT lymphoma is the presence of lymphoepithelial lesions, which result from invasion of mucosal glands and crypts by the neo­ plastic lymphocytes. These cells are positive for CD19, CD20, and CD79a and negative for CD5 and CD10. Recurrent cytogenetic abnormalities include t(11;18), t(14;18), t(1;14), t(3;14), and trisomy 8. The t(11;18) is most common, occurring in up to 50% of MALT lymphomas. It results in the fusion of the apoptosis inhibitor 2 (API2) gene and the MALT1 gene, resulting in activation of nuclear factor-κB (NF-κB). Unlike other indolent B-cell lymphomas, MALT lymphomas present most commonly with stage I or II disease. In these cases, radiation therapy may be curative. Alternatively, patients may respond to antibiotics for the associated underlying infection. Treatment of symptomatic or organ-impairing relapsed, refractory, or advanced-stage disease is similar to approaches used in FL with chemotherapy, immunotherapy, or chemoimmunotherapy. Lymphoplasmacytic Lymphoma  About 1% of all NHLs will be LPLs, which are indolent B-cell NHLs with lymphoplasmacytic differentiation, most commonly associated with a monoclonal IgM paraprotein. Nearly all patients will have stage IV disease at diagnosis with bone marrow involvement. Patients with high levels of circulating IgM paraproteins constitute a specific entity known as Waldenström’s macroglobulinemia and can have symptoms due to hyperviscosity as a result of the circulating IgM. Activating mutations in MYD88, an adap­ tor protein that is involved in signaling downstream of the Ig receptor leading to NF-κB activation, are present in >90% of cases. Tumor biop­ sies are notable for proliferation of small lymphocytes, lymphoplasma­ cytic cells, and plasma cells, and malignant lymphocytes are positive for CD19, CD20, and surface IgM but generally negative for CD5 and CD10. Like the other indolent NHLs, treatment is indicated for disease that causes symptoms or interferes with organ function; hyperviscosity related to elevated serum IgM and paraneoplastic neuropathy are addi­ tional indications for therapy. Single-agent rituximab may be useful for low-volume disease but can be associated with a transient rise in serum IgM concentrations that can cause or exacerbate hyperviscos­ ity. Chemoimmunotherapy with regimens such as BR and rituximab, cyclophosphamide, and dexamethasone is active, as are myeloma therapies such as bortezomib. Ibrutinib and zanubrutinib in combina­ tion with rituximab are highly active in this disease and are options for both previously untreated and relapsed disease. Given that 85% of IgM remains intravascular, acute relief of hyperviscosity symptoms can be obtained by plasmapheresis. For recurrent disease, one can often use agents that were previously used. For patients with more refractory LPL, the mammalian target of rapamycin (mTOR) inhibitor everolimus and the bcl-2 inhibitor venetoclax are active. Selected patients with relapsed disease are considered for high-dose therapy with autologous or allogeneic stem cell transplantation. The results seen are similar to those of other indolent lymphomas. CHAPTER 113 Non-Hodgkin’s Lymphoma Mantle Cell Lymphoma  MCL composes ∼6% of NHLs. It is an intermediate-grade lymphoma that, like the indolent B-cell NHLs, is not curable with conventional therapies but, like the aggressive lymphomas, often requires more aggressive chemoimmunotherapy regimens with or without an autologous stem cell transplant to achieve a reasonable response duration. This therapy is not curative, however, and median survival with this disease is on the order of 5–10 years. An exception to this is a more indolent SOX11 variant that often presents with circulating disease with splenomegaly but without significant lymphadenopathy and with a low Ki67 (<10%). This subset behaves more like the indolent B-cell NHLs and can be observed until treat­ ment is indicated by symptoms or organ function impairment. Simi­ larly, there is a blastic variant with a high Ki67 index that is associated with a poor prognosis and a median OS of only 18 months. For other patients, prognosis is best predicted by the biologic MCL International Prognostic Index (MIPI), which factors in age, performance status, LDH, white blood cell count, and Ki67 expression to determine a risk group. This disease is more common in men, and the average age of diagnosis is 63. MCLs with a mutation in TP53 or a complex karyo­ type are particularly high risk as well. Over two-thirds of patients will have stage IV disease, mostly with bone marrow and peripheral blood involvement, at the time of diagnosis. Another common extranodal site of involvement is the gastrointestinal tract, where diffuse lymphoma­ tous polyposis may be seen. The pathognomonic cytogenetic finding in MCL is t(11;14), which brings the gene for the cell cycle control protein cyclin D1 under the control of the immunoglobulin heavy chain gene promoter on chromo­ some 14. This translocation is present in >90% of cases. The remaining cases usually overexpress cyclin D2, cyclin D3, or cyclin E. Tumor cells also are positive for B-cell markers CD19 and CD20, as well as CD5. They usually lack CD10 and CD23. Therapies for MCL are evolving. Patients with localized dis­ ease might be treated with combination chemotherapy followed by radiotherapy; however, these patients are exceedingly rare. Similarly, patients with the indolent variant can be observed until disease pro­ gresses to cause symptoms or signs of organ function impairment. For the usual presentation with disseminated disease, standard lymphoma treatments like R-CHOP have been unsatisfactory, with the minority of patients achieving complete remission. The addition of high-dose cytarabine to an R-CHOP–like backbone with or without consolidation autologous stem cell transplantation in first remission has improved progression-free survival, but it has not elicited cures in this disease. These include the Nordic regimens and R-HyperCVAD (rituximab, cyclophosphamide, vincristine, doxorubicin, dexamethasone, cytara­ bine, and methotrexate). BR has activity in this disease and is more effective and better tolerated than R-CHOP. Newer studies with short follow-up suggest that strategies that combine BR with cytarabine with or without autologous stem cell transplant may be effective and well tolerated. The SHINE study randomized patients to BR alone versus BR plus ibrutinib and showed a modest benefit with the addi­ tion of ibrutinib. It is not clear, however, if this benefit is greater than the sequencing of upfront BR followed by BTK inhibition at relapse. Maintenance rituximab, following a good response to induction che­ motherapy or after autologous stem cell transplant, also improves out­ comes over observation alone. Increasing evidence suggests that with modern induction therapies, high-dose chemotherapy and autologous stem cell rescue may no longer provide benefit in the frontline setting. The randomized European TRIANGLE study showed no benefit of autologous transplant when added to induction chemoimmunotherapy with ibrutinib followed by rituximab and ibrutinib maintenance. An ongoing randomized study in the United States is asking a similar question for patients who are treated with chemoimmunotherapy without upfront BTK inhibition. For relapsed disease, the BTK inhibi­ tors ibrutinib, acalabrutinib, and zanubrutinib have single-agent activ­ ity with a response rate of almost 70% but a response duration of only 18–24 months. These drugs are being explored in combination with chemotherapy as well as with the BCL2 antagonist venetoclax. AntiCD19–directed CAR-T therapies are approved for the treatment of relapsed/refractory MCL; two-thirds of patients who had progressed after chemoimmunotherapy (with or without an autologous stem cell transplant) and BTK inhibition have achieved complete responses, many of which are durable through limited follow-up. As in FL, longer follow-up is needed to determine if some of these patients may be cured, which would make this the only curative therapy for this disease outside of an allogeneic stem cell transplantation. The noncovalent BTK inhibitor pirtobrutinib has activity in MCL that has progressed on prior covalent BTK inhibitors and is now approved in this setting. Drugs such as lenalidomide, venetoclax, bortezomib, and temsirolimus can similarly induce transient partial responses. Appropriate patients who respond to salvage therapy, with the exception of CAR-T therapy, should be considered for allogeneic stem cell transplant, which can lead to long-term disease-free survival in 30–50% of patients. PART 4 Oncology and Hematology ■ ■MATURE (PERIPHERAL) T-CELL DISORDERS Mature T-cell disorders include cutaneous lymphomas, such as mycosis fungoides, and the PTCLs, some of which are distinguished based on specific clinical presentations or contexts or by molecular or biologic features, but many of which fall into the category of PTCL not other­ wise specified (NOS). T-cell NHLs are significantly rarer than B-cell NHLs, and as such, our understanding of their biology is less advanced and our therapies are less well developed. While some T-cell lympho­ mas, like mycosis fungoides, can behave indolently and some, like ALK-positive ALCL, can be cured with chemotherapy, the majority are associated with a poor prognosis. The advent of genomic technologies is enhancing our ability to understand the genetic and biologic basis of these neoplasms. Mycosis Fungoides  Mycosis fungoides is also known as cutaneous T-cell lymphoma. This lymphoma is more often seen by dermatologists than internists. The median age of onset is in the mid-fifties, and the disease is more common in males and in blacks. Mycosis fungoides is an indolent lymphoma, with patients often having several years of eczematous or dermatitic skin lesions before the diagnosis is finally established. The skin lesions progress from patch stage to plaque stage to cutaneous tumors. Early in the disease, biopsies are often difficult to interpret, and the diagnosis may only become apparent by observing the patient over time. Adenopathy may reflect involvement with mycosis fungoides or be read as dermatopathic change. In advanced stages, the lymphoma can spread to lymph nodes and visceral organs. Patients with this lymphoma may develop general­ ized erythroderma and circulating tumor cells, called Sézary’s syndrome. Rare patients with localized early-stage mycosis fungoides can be cured with radiotherapy, often total-skin electron beam irradiation. More advanced disease has been treated with topical glucocorticoids, topical nitrogen mustard, phototherapy, psoralen with ultraviolet A (PUVA), extracorporeal photopheresis, retinoids (bexarotene), electron beam radiation, interferon, antibodies, fusion toxins, histone deacety­ lase inhibitors, brentuximab (for CD30+ disease), and systemic cyto­ toxic therapy. Mogamulizumab, an anti-CCR4 antibody, has activity in this disease and has been approved by the U.S. Food and Drug Adminis­ tration for this indication. Unfortunately, these treatments are palliative. Peripheral T-Cell Lymphoma, Not Otherwise Specified  PTCLs include a number of entities, which constitute 15% of all NHLs in adults. PTCL NOS, which composes 6% of all NHLs, is the term used for cases that are not other entities defined in the WHO classification. Named varieties include ALCL, angioimmunoblastic T-cell lymphoma (AITL), hepatosplenic T-cell lymphoma, enteropathy-associated T-cell lymphoma, and subcutaneous panniculitis T-cell lymphoma. PTCL NOS is a disease of older individuals, with a median age at presentation of 65, and the majority of patients will have advanced-stage disease at diagnosis, with involvement of the bone marrow, liver, spleen, and skin being common. Associated “B” symptoms and pruritis are also com­ mon. These lymphomas can be associated with a reactive eosinophilia as well as hemophagocytic syndrome. The IPI has been applied to PTCL NOS and provides some assessment of outcomes, but even the low-risk group has a median OS of just >2 years. This diagnostic category is a collection of heterogeneous lympho­ mas that vary widely and lack typical findings of other specific PTCL subgroups. Because of this heterogeneity, histology, immunophe­ notype, and genetics are variable. Often lymph nodes are effaced by atypical lymphoid cells of various sizes, sometimes associated with vascular proliferation or an infiltrate of eosinophils and/or macro­ phages. As most of these lymphomas behave aggressively, note is often made of mitotic and apoptotic figures as well as geographic necrosis. The cells often are positive for CD3, and the majority of PTCL NOS is positive for CD4 rather than CD8, but some are negative for both markers. There can be loss of more mature T-cell markers like CD5 and CD7, and this is associated with a more aggressive course. There are some recurrent translocations, including t(7;14), t(11;14), inv(14), and t(14;14), all of which involve the TCR genes. The most common primary therapy for PTCL NOS involves a CHOP-like chemotherapy backbone—either CHOP alone or CHOP in combination with etoposide (CHOEP). The latter may provide the most benefit to younger patients and patients with more favorable dis­ ease risk factors. Brentuximab in combination with cyclophosphamide, doxorubicin, and prednisone (CHP) has been tested in a randomized clinical trial against CHOP in CD30+ T-cell lymphomas; progressionfree survival was improved with the brentuximab-containing arm, and this was most pronounced for patients with ALCL (see below). Autolo­ gous stem cell transplant has been investigated for patients in their first remission and does seem to improve progression-free survival in certain contexts. Drugs such as gemcitabine, bendamustine, and prala­ trexate have activity in relapsed disease, as do the histone deacetylase inhibitors romidepsin and belinostat. The PI3 kinase inhibitor duvelisib is being investigated in these diseases with early signals of activity. All of these agents are associated with transient responses in a minority of patients. Patients should be considered for clinical trials. For patients who do achieve remission, reduced-intensity allogeneic stem cell trans­ plantation can yield long-term nonrelapse survival rates of ∼40–50%. Angioimmunoblastic T-Cell Lymphoma  AITL constitutes ∼20% of T-cell NHLs and ∼4% of all NHLs diagnosed. Patients present with a variety of signs and symptoms, most often including lymphade­ nopathy, hepatosplenomegaly, “B” symptoms, rash, polyarthritis, and hemolytic anemia. Over 80% of patients have advanced-stage disease at diagnosis, and bone marrow involvement is common. Polyclonal hypergammaglobulinemia is common, as are elevated LDH, eosino­ philia, a positive Coombs test, and opportunistic infections. On biopsy, lymph nodes are effaced by a polymorphous infiltrate of lymphocytes, ranging in size and shape, and of immunoblasts. The neoplastic lymphocytes are positive for CD3 as well as CXCL13, PD-1, CD10, and BCL6, most closely resembling CD4-positive follicular helper T cells. There is an expanded follicular dendritic cell network surrounding tumor cells. Scattered immunoblasts are often EBV posi­ tive and may give rise to secondary EBV-positive B-cell lymphomas at a later time. Genetic analysis of this disease has revealed recurrent mutations in TET2 (76%), DNMT3 (33%), and IDH2 (20%). A subset of AITL can remit with immunosuppression with agents like glucocorticoids or methotrexate. Most patients, however, will need combination chemotherapy with regimens like those used in PTCL NOS. Median response duration is short, and median OS is only 15–36 months. Treatment of relapsed disease is similar to that of relapsed PTCL NOS. Anaplastic Large-Cell Lymphoma  ALCL is the next most com­ mon T-cell lymphoma after AITL but is more common in children, accounting for up to 10% of pediatric lymphomas. Approximately 40–60% of cases harbor t(2;5), which fuses a portion of the nucleolar protein nucleophosmin-1 (NPMI) gene to a part of the anaplastic lymphoma kinase (ALK) gene, the product of which has constitutive tyrosine kinase activity. These patients have a much more favorable prognosis compared to ALK-negative ALCL, akin to that of DLBCL. There is an additional, more indolent and favorable subtype that occurs in the breast tissue of patients with breast implants, and there is a cuta­ neous variant. In general, this is a disease that is more common in men. ALK-positive disease is a disease of younger patients, with a median age at diagnosis of 34 years, whereas the median age at diagnosis of ALK-negative patients is 58. With the exception of the cutaneous vari­ ant and the variant associated with breast implants, most patients pres­ ent with rapidly growing lymphadenopathy with or without extranodal involvement; “B” symptoms are common. Most cases of ALCL involve large atypical lymphocytes with horse­ shoe-shaped nuclei with prominent nucleoli (“hallmark” cells). Tumor cells tend to be localized within the lymph node sinuses, and almost all are positive for CD30 but negative for CD15. A majority will also express CD3, CD25, CD43, and CD4. ALK-rearranged ALCL can be diagnosed by fluorescence in situ hybridization (FISH) cytogenetics for t(2;5) or by immunohistochemical staining for ALK. ALCL is generally treated with CHOP, although like PTCL NOS, CHOEP may benefit younger patients, particularly with ALK-positive disease. Overall, ALCL has a better prognosis than PTCL, and this is particularly true for ALK-positive disease, which has an 8-year OS rate of 82%, versus 49% for ALK-negative disease. Relapsed ALK-positive ALCL is treated similarly to relapsed DLBCL, with salvage combination chemotherapy to identify chemotherapy sensitivity followed by autolo­ gous stem cell transplant. For patients with chemotherapy-insensitive disease or for ALK-negative disease, the conjugated anti-CD30 anti­ body to monomethyl auristatin E (MMAE)/brentuximab is highly active, with a response rate of 86% and a complete response rate of 57%. As mentioned earlier, brentuximab in combination with CHP chemotherapy is an approved frontline regimen for the treatment of CD30+ T-cell lymphomas, including ALCL. The ALK inhibitors, including crizotinib, are active in refractory ALK-positive ALCL with excellent outcomes. Other PTCL Subtypes  Enteropathy-associated T-cell lymphoma, hepatosplenic T-cell lymphoma, and subcutaneous panniculitis-like T-cell lymphoma are other less common PTCL subtypes. Enteropathytype intestinal T-cell lymphoma is a rare disorder. Type I occurs in patients with a history of gluten-sensitive enteropathy and is associ­ ated with HLADQA1∗0501, DQB1∗0201; a gluten-free diet can pre­ vent the development of this lymphoma. Type II is now referred to as monomorphic epitheliotropic intestinal T-cell lymphoma and is not associated with celiac disease. Patients are frequently cachectic and sometimes present with intestinal perforation. The prognosis is poor, with a median survival of 10 months. Therapy is often with combina­ tion chemotherapy, including high-dose methotrexate, and autologous stem cell transplant in first remission. Hepatosplenic γδ T-cell lymphoma is a systemic illness that presents with sinusoidal infiltration of the liver, spleen, and bone marrow by malignant T cells. Tumor masses generally do not occur. The disease is associated with systemic symptoms and is often difficult to diagnose. Recurrent genetic events include isochromosome 7q and trisomy 8. Treatment outcome is poor, but regimens that include ifosfamide, such as ifosfamide, carboplatin, and etoposide (ICE) or ifosfamide, etopo­ side, and cytarabine (IVAC), are associated with better outcomes in small series of patients. Responding patients should be considered for allogeneic stem cell transplantation. CHAPTER 113 Non-Hodgkin’s Lymphoma Subcutaneous panniculitis-like T-cell lymphoma is a rare disorder that is often confused with panniculitis. Patients present with multiple subcutaneous nodules, which progress and can ulcerate. There is a more indolent form that tends to express α/β TCRs and can be man­ aged with immune suppression, whereas lymphomas that express γ/δ TCRs are more aggressive and are associated with a worse prognosis and coincident hemophagocytic syndrome. This is a disease of young men in their fifth and sixth decades of life. Patients with aggressive disease are managed with multiagent chemotherapy, and responding patients should be considered for allogeneic stem cell transplantation. Adult T-Cell Leukemia/Lymphoma  Adult T-cell leukemia/ lymphoma (ATLL) is a disease that is most prevalent in Japan and the Caribbean basin (Chap. 207). It is a neoplasm that is driven by HTLV-1, often contracted through the breast milk of infected mothers. The average age at diagnosis is 60, so there is a long latency between viral infection and viral transformation, and only 4% of infected patients will develop the disease. This suggests that HTLV-1 may not be suffi­ cient to cause the malignant phenotype. There are four disease variants: acute (60% of patients), lymphomatous (20% of patients), chronic (15% of patients), and smoldering (5% of patients); prognosis varies across these groups, with median survival times of 6, 10, and 24 months, and not yet reached, respectively. Presentation depends on the subtype, but most commonly, patients present with circulating disease and bone marrow involvement, hypercalcemia, lytic bone lesions, lymphadenop­ athy, hepatosplenomegaly, skin lesions, and opportunistic infections. The pathognomonic finding is the malignant “flower cell” that is positive for CD4 and CD25, as well as CD2, CD3, and CD5 but lack­ ing CD7 (Fig. 113-7). Combination chemotherapy is generally used, but for patients fortunate enough to respond, response durations are very short. Other active agents in this disease include the antiretro­ viral agent zidovudine, interferon α, arsenic and mogamulizumab, a humanized monoclonal antibody that blocks the CCR4 chemokine receptor. In any patients who do respond to therapy, allogeneic stem cell transplant should be considered. Extranodal NK/T-Cell Lymphoma, Nasal Type  Extranodal NK/T-cell lymphoma, nasal type, is a lymphoma that is associated with # 44 - 114 Hodgkin’s Lymphoma ### 114 Hodgkin’s Lymphoma FIGURE 113-7  Adult T-cell leukemia/lymphoma. Peripheral blood smear showing leukemia cells with typical “flower-shaped” nucleus. EBV infection in nearly all cases and more common in Asia and native populations in Peru. It usually presents with a mass and obstructive symptoms in the upper aerodigestive tract with occasional extranodal sites, but over two-thirds of patients will have localized disease. It is more common in men, and the median age at diagnosis is 60. This disease has its own prognostic score, which takes into account the presence or absence of “B” symptoms, disease stage, whether LDH is elevated, and whether there is lymph node involvement. EBV viral load at diagnosis and at the end of therapy is also predictive. PART 4 Oncology and Hematology Treatment for early-stage disease is usually with combined-modality therapy of chemotherapy (commonly using etoposide, ifosfamide, cisplatin, and dexamethasone) and intensity-modulated radiation therapy (50–55 Gy), and patients with localized disease involving the nasal passages do quite well, with 3-year OS of ∼85%. Patients with more advanced-stage disease do poorly, with disseminated extranodal relapse occurring frequently, and the median OS is only 4.3 months. The most commonly used treatment regimen is the SMILE regi­ men (dexamethasone, methotrexate, ifosfamide, l-asparaginase, and etoposide). ■ ■FURTHER READING Horwitz S et al: The ECHELON-2 Trial: 5-year results of a random­ ized, phase III study of brentuximab vedotin with chemotherapy for CD30-positive peripheral T-cell lymphoma. Ann Oncol 33:288, 2022. Morschhauser F et al: Rituximab plus lenalidomide in advanced untreated follicular lymphoma. N Engl J Med 379:934, 2018. Tille H et al: Polatuzumab vedotin in previously untreated diffuse large B-cell lymphoma. N Engl J Med 386:351, 2022. Westin JR et al: Survival with axi-cabtagene ciloleucel in large B-cell lymphoma. N Engl J Med 389:148, 2023. Caron A. Jacobson, Dan L. Longo Hodgkin’s Lymphoma Hodgkin’s lymphoma (HL) is a malignancy of mature B lymphocytes. It represents ~10% of all lymphomas diagnosed each year. The majority of HL diagnoses are classical HL (cHL), but there is a second subtype of HL, nodular lymphocyte-predominant HL (NLPHL). While this diagnosis does resemble cHL morphologically in certain respects, there is some evidence that it is more related to the indolent B-cell non-Hodgkin’s lymphomas (NHLs) biologically than it is to cHL. The majority of this chapter will be specific to cHL, with a discussion of NLPHL at the end. cHL is one of the success stories of modern oncology. Until the advent of extended-field radiotherapy in the mid-twentieth century, it was a highly fatal disease of young people. Radiation therapy cured some patients with early-stage disease, and the introduction of mul­ tiagent chemotherapy in the 1970s resulted in further improved cure rates, for both patients with early- and advanced-stage disease. Cure rates now are >85%. The new challenge in the treatment of HL is late therapy-related toxicity, including a high rate of secondary malignan­ cies and cardiovascular disease. Current clinical trials are aimed at minimizing this risk while preserving efficacy. ■ ■EPIDEMIOLOGY AND ETIOLOGY HL is of B-cell origin. The incidence of HL appears fairly stable, with an estimated 8830 new cases diagnosed in the United States in 2023. HL is more common in whites than in blacks and more common in males than in females. A bimodal distribution of age at diagnosis has been observed, with one peak incidence occurring in patients in their twen­ ties and the other in those in their eighties. Some of the late age peak may be attributed to confusion among entities with similar appearance such as anaplastic large-cell lymphoma and T-cell/histiocyte–rich B-cell lymphoma. There are four distinct subtypes of cHL that are differentiated based on their histopathologic features (Table 114-1): nodular scle­ rosis, mixed cellularity, lymphocyte-rich, and lymphocyte-depleted. Patients in the younger age groups diagnosed in the United States largely have the nodular sclerosing subtype of HL. Elderly patients, patients infected with HIV, and patients in developing countries more commonly have mixed-cellularity HL or lymphocyte-depleted HL. Together, nodular sclerosis and mixed-cellularity types account for nearly 95% of cases. Infection by HIV is a risk factor for developing HL. In addition, an association between infection by Epstein-Barr virus (EBV) and HL has been suggested. A monoclonal or oligoclonal pro­ liferation of EBV-infected cells in 20–40% of the patients with HL has led to proposals for this virus having an etiologic role in HL. However, the matter is not settled definitively. Viral oncogenesis appears to play a greater role in HIV-related cHL: EBV can be detected in nearly all cases of HIV-associated cHL, compared to only one-third of cases of non–HIV-associated cHL. Reed-Sternberg (HRS) cells are the malig­ nant cells in HL. HRS cells in HIV-associated cHL express the EBVtransforming protein latent membrane protein 1 (LMP-1), and the EBV genomes from multiple disease sites in the same HIV-associated cHL patient are episomal and clonal, suggesting that EBV is directly involved in early lymphomagenesis. Histologically, the HRS cell is diagnostic of cHL (Fig. 114-1). These cells are large cells with abundant cytoplasm with bilobed and/ or multiple nuclei. By immunohistochemistry, they are often PAX-5 positive but have low to no expression of other B-cell antigens like CD19 and CD20. They express CD15 and CD30 in 85 and 100% of cases, respectively. These cells, though, comprise <1% of the tumor cellularity, with the majority of the tumor made up of a surround­ ing inflammatory infiltrate of polyclonal lymphocytes, eosinophils, neutrophils, macrophages, plasma cells, fibroblasts, and collagen. The HRS cell interacts with its microenvironment via cell-cell contact and elaboration of growth factors and cytokines, which results in a sur­ rounding cellular milieu that protects it from host immune attack. The surrounding environmental cells likewise support the HRS cells via cell-cell signaling and cytokine production, which provides signals TABLE 114-1  World Health Organization Classification of Hodgkin’s Lymphoma Nodular lymphocyte-predominant Hodgkin’s lymphoma Classical Hodgkin’s lymphoma Nodular sclerosis Lymphocyte-rich Mixed cellularity Lymphocyte-depleted FIGURE 114-1  Hodgkin’s disease: A classic Reed-Sternberg (RS) cell is present near the center of the field. RS cells are large cells with a bilobed nucleus and prominent nucleoli surrounded by a pleiomorphic cellular infiltrate. (From DL Kasper: Harrison’s Principles of Internal Medicine, 16th ed. New York, NY: McGraw-Hill; 2005, Fig. 97-11, p. 654.) that promote proliferation and survival of the HRS cell itself. Interest­ ingly, 97% of HRS cells in cHL harbor genetic aberrations in the PD-L1 locus on chromosome 9p24.1, resulting in overexpression of PD-L1, the ligand for the inhibitory PD-1 receptor on immune cells. This is one mechanism whereby the HRS cell may be able to avoid immune destruction in its inflammatory microenvironment and may contribute to the generalized immune suppression in HL patients. APPROACH TO THE PATIENT Classical Hodgkin’s Lymphoma Most patients with cHL present with palpable lymphadenopathy that is nontender; in most patients, these lymph nodes are in the neck, supraclavicular area, and axilla. More than half of the patients will have mediastinal adenopathy at diagnosis, and this is some­ times the initial manifestation. Subdiaphragmatic presentation of cHL is unusual and more common in older males. One-third of patients present with fevers, night sweats, and/or weight loss, or “B” symptoms. Occasionally, HL can present as a fever of unknown ori­ gin. This is more common in older patients who are found to have mixed-cellularity HL in an abdominal site. Rarely, the fevers persist for days to weeks, followed by afebrile intervals and then recurrence of the fever. This pattern is known as Pel-Ebstein fever. HL can occa­ sionally present with unusual manifestations. These include severe and unexplained itching, cutaneous disorders such as erythema nodosum and ichthyosiform atrophy, paraneoplastic cerebellar degeneration and other distant effects on the CNS, nephrotic syn­ drome, immune hemolytic anemia and thrombocytopenia, hyper­ calcemia, and pain in lymph nodes on alcohol ingestion. Evaluation of patients with HL will typically begin with a careful history and physical examination. Patients should be asked about the presence or absence of “B” symptoms. Comorbid diagnoses that may impact therapy should be reviewed, including a history of pulmonary disease and congestive heart failure given the use of chemotherapy drugs that can cause both lung and heart toxicity. A physical examination should pay attention to the peripherally accessible sites of lymph nodes and to the liver and spleen size. Laboratory evaluation should include a complete blood count with differential; erythrocyte sedimentation rate (ESR); chemistry stud­ ies reflecting major organ function including serum albumin; and HIV and hepatitis virus testing. A positron emission tomography (PET)/computed tomography (CT) scan is used for staging and is more accurate than a bone marrow biopsy for evaluation of bone marrow involvement as the bone marrow involvement in cHL tends to be patchy and therefore potentially missed on a unilateral bone TABLE 114-2  The Ann Arbor Staging System for Hodgkin’s Lymphoma STAGE DEFINITION I Involvement of a single lymph node region or lymphoid structure (e.g., spleen, thymus, Waldeyer’s ring) II Involvement of two or more lymph node regions on the same side of the diaphragm (the mediastinum is a single site; hilar lymph nodes should be considered “lateralized” and, when involved on both sides, constitute stage II disease) III Involvement of lymph node regions or lymphoid structures on both sides of the diaphragm   III1   Subdiaphragmatic involvement limited to spleen, splenic hilar nodes, celiac nodes, or portal nodes   III2   Subdiaphragmatic involvement includes paraaortic, iliac, or mesenteric nodes plus structures in III1 IV Involvement of extranodal site(s) beyond that designated as “E”     More than one extranodal deposit at any location     Any involvement of liver or bone marrow A No symptoms B Unexplained weight loss of >10% of the body weight during the 6 months before staging investigation   Unexplained, persistent, or recurrent fever with temperatures >38°C during the previous month CHAPTER 114   Recurrent drenching night sweats during the previous month E Localized, solitary involvement of extralymphatic tissue, excluding liver and bone marrow Hodgkin’s Lymphoma marrow biopsy. The initial evaluation of a patient with HL or NHL is similar. In both situations, the determination of an accurate ana­ tomic stage is an important part of the evaluation. Staging is done using the Ann Arbor staging system (Table 114-2). The diagnosis of HL is established by review of an adequate biopsy specimen by an expert hematopathologist. HL is a tumor characterized by rare neoplastic cells of B-cell origin (immunoglob­ ulin genes are rearranged but not expressed) in a tumor mass that is largely polyclonal inflammatory infiltrate, probably a reaction to cytokines produced by the tumor cells. The differential diagnosis of a lymph node biopsy suspicious for HL includes inflammatory processes, mononucleosis, NHL, phenytoin-induced adenopathy, and nonlymphomatous malignancies. Staging for cHL is anatomically based given the propensity of the disease to march from one lymph node group to the next group, often contiguous to the first. Staging is important for selecting therapy of appropriate duration and intensity, but the outcome of optimal therapy for all the stages is excellent. Patients are stratified based on whether they have early-stage disease (stage I or II) or advanced-stage disease (stage III or IV). Patients with early-stage disease have a better prognosis overall but are further classified as favorable or unfavorable based on a variety of factors. These fac­ tors vary from study to study but include bulky disease, number of lymph node areas involved, an elevated ESR (>30 if “B” symptoms are present; >50 if “B” symptoms are absent), and age. Prognosis in advanced-stage disease is best predicted by the International Prog­ nostic Score (IPS), which ascribes 1 point for male sex, older age (>45 years), stage IV disease, serum albumin <4 g/dL, hemoglobin <10.5 g/dL, white blood cell count ≥15,000/μL, and a lymphocyte count <600/μL and/or <8% of white blood cell count. Five-year progression-free survival ranges from 88% for patients with no risk factors to 62% for patients with four or more factors, but very few patients have multiple risk factors. TREATMENT Classical Hodgkin’s Lymphoma The overwhelming majority of patients with HL will be cured with either chemotherapy alone or a combination of chemotherapy and radiation therapy. It has long been appreciated that patients with advanced-stage disease do not benefit from the addition of radiation therapy to chemotherapy and are thus treated with chemotherapy alone. For early-stage disease, however, treatment with combined-modality therapy has been associated with a small decrease in risk of relapse but with an increased risk of late toxicity including secondary malignancies, thyroid disease, and prema­ ture cardiovascular disease and stroke resulting in minimal or no improvement in long-term survival. Much of this risk can be attrib­ uted to radiation therapy. Thus, investigation into the treatment of early-stage HL at present is aimed at trying to maximize treatment outcome without using radiotherapy. This is an area of controversy in the treatment of HL. EARLY-STAGE DISEASE The most common chemotherapy regimen used to treat early-stage HL in the United States is ABVD (doxorubicin, bleomycin, vin­ blastine, and dacarbazine). This regimen is given every other week, with each cycle including two treatments. In patients with low-risk, or favorable, disease, the use of four to six cycles of ABVD alone, without radiation therapy, results in progression-free and overall survival rates of 88–92% and 97–100%, respectively, at 5–7 years. This may be associated with a slightly increased risk of relapse when compared with abbreviated chemotherapy (ABVD for four cycles) followed by involved field radiation therapy (30 Gy), but with no difference in overall survival owing to the excellent salvage strate­ gies used for relapsed HL and to the late toxicities seen following radiation therapy to the chest. German studies have examined a very abbreviated chemotherapy regimen (ABVD for two cycles) and low-dose radiation (20 Gy) for particularly good-risk disease with two or fewer lymph node areas involved and found that this was equally effective to standard combined-modality therapy of ABVD for four cycles and 30 Gy of radiation. However, long-term followup is not yet available to assess the impact of the lower radiotherapy dose on late toxicities. Finally, the use of an early interim PET/CT scan can aid decisions regarding the duration and extent of therapy. In one study, a negative PET/CT scan after three cycles of ABVD predicted for excellent outcomes with no additional therapy; in another, a negative PET/CT scan after two cycles of ABVD pre­ dicted for good outcomes with two additional cycles of ABVD alone, without radiation therapy. PART 4 Oncology and Hematology For unfavorable-risk disease, the omission of radiation ther­ apy following chemotherapy is associated with a more significant increased risk of relapse compared to favorable-risk disease, but again with no change in overall survival. For these patients, treat­ ment options would include ABVD for four cycles followed by involved field radiation therapy or ABVD alone for six cycles. Treatment decisions are often based on the extent of the radiation field and the unfavorable risk factor, with patients with nonbulky disease being candidates for chemotherapy alone if radiation would be contraindicated for another reason. Combined modality therapy has typically been used for patients with bulky disease, although patients with bulky disease who have a negative PET/CT scan after chemotherapy may not benefit from additional radiation therapy. Alternative chemotherapy regimens to ABVD have been devel­ oped and include the Stanford V regimen and escalated BEACOPP (bleomycin, etoposide, doxorubicin, cyclophosphamide, vincris­ tine, procarbazine, and prednisone). Neither of these regimens has resulted in improved outcomes in patients with early-stage disease. ADVANCED-STAGE DISEASE Patients with advanced-stage disease do not benefit from the addi­ tion of radiation therapy after a complete response to chemotherapy alone and should be treated with chemotherapy alone. The most common regimens used in the United States include ABVD or brentuximab vedotin plus doxorubicin, vinblastine, and dacarba­ zine (AVD) for six cycles. Brentuximab is an antibody-drug con­ jugate (ADC) that targets CD30 on the HRS cell and is conjugated to the microtubule inhibitor monomethyl auristatin E (MMAE). It was approved in the relapsed setting as a single agent and then was tested in phase 1 and 2 trials in combination with AVD chemo­ therapy for the upfront treatment of advanced-stage cHL. A phase 3 study, ESCHELON-1, randomized patients with advanced-stage cHL to either ABVD or brentuximab-AVD and demonstrated both a progression-free and overall survival benefit with brentux­ imab-AVD. Again, Stanford V and escalated BEACOPP have been evaluated in advanced-stage disease and are not associated with an improvement in overall survival but are associated with increased toxicity. The small fraction of patients who do not achieve complete remission with chemotherapy alone (partial responders with persis­ tent PET scan positivity account for <10% of patients) may benefit from the addition of involved field radiotherapy. Drugs that target the PD-1/PD-L1 axis have been developed for the treatment of relapsed HL based on the known genomic alterations leading to PD-L1 overexpression on the HRS cell (see “Relapsed Disease,” below). In the setting of relapsed disease, these drugs, which include pembrolizumab and nivolumab, have very high response rates and are associated with durable responses. Phase 2 studies combining these drugs with either brentuximab (nivolumab) or ICE (nivolumab; ifosfamide, carboplatin, and etopo­ side) or GND (pembrolizumab; gemcitabine, vinorelbine, and doxo­ rubicin) chemotherapy have demonstrated high complete response rates in order to get patients to autologous stem cell transplantation. A multicenter randomized trial comparing brentuximab-AVD to nivolumab-AVD in the upfront treatment of advanced-stage cHL has been presented, and there was a progression-free survival ben­ efit with nivolumab-AVD and the regimen had an arguably more favorable toxicity profile. We await longer follow-up and U.S. Food and Drug Administration review of these results to determine if this study establishes a new standard of care for the upfront treatment of advanced-stage cHL. RELAPSED DISEASE Patients who relapse after primary therapy of HL can frequently still be cured. Patients who relapse after an effective chemother­ apy regimen are usually not curable with subsequent chemotherapy administered at standard doses. Alternative salvage chemotherapy administered at standard doses, then, is given in order to document sensitivity to chemotherapy and to achieve maximum reduction of tumor mass. For patients who respond completely or nearly so, autologous stem cell transplantation can cure over half of patients. Standard salvage chemotherapy regimens have historically included ICE and GND. Newer combinations, including brentuximab with immune checkpoint inhibitors such as nivolumab, have also been tested with promising results for patients who have not seen brentuximab in the frontline setting. The combinations of ICE or GND with nivolumab or pembrolizumab, respectively, are similarly highly effective and lead to high complete remission rates and success in getting patients to definitive autologous stem cell trans­ plantation. These novel combinations have largely replaced standard sal­ vage chemotherapy approaches, as the chemotherapy/immunotherapy combinations appear to be more effective and are associated with higher rates of durable response after autologous stem cell trans­ plantation, perhaps owing to the chemosensitizing effects that have been observed following immune checkpoint inhibition. Studies are ongoing to investigate whether autologous transplant is necessary for patients who have a favorable response to chemotherapy/immu­ notherapy combinations based on this observed phenomenon. For patients with early-stage disease who do not respond sufficiently to salvage chemotherapy, radiation therapy can be very effective to achieve a remission; whether to consolidate such a remission with an autologous stem cell transplant is debated. Brentuximab is also used as a maintenance therapy following successful autologous stem cell transplantation based on results of the AETHERA study, a randomized trial of brentuximab maintenance versus observation. Finally, anti-CD30 chimeric antigen receptor (CAR) T-cell therapy has been tested in multiply relapsed cHL with promising early results; these products are now being tested in multicenter phase 2 clinical trials. # 45 - 115 Less Common Lymphoid and Myeloid Malignancies ### 115 Less Common Lymphoid and Myeloid Malignancies SURVIVORSHIP Because of the very high cure rate in patients with HL, long-term complications have become a major focus for clinical research. In fact, in some series of patients with early-stage disease, more patients died from late complications of therapy than from HL itself. This is particularly true in patients with localized disease. The most serious late side effects include second malignancies and cardiac injury. Patients are at risk for the development of acute leukemia in the first 10 years after treatment with combination chemotherapy regimens that contain alkylating agents plus radiation therapy. The risk for development of acute leukemia is greater after MOPP-like (mechlorethamine, vincristine, procarbazine, and prednisone) and BEACOPP-like regimens than with ABVD or brentuximab-AVD. The risk of development of acute leukemia after treatment for HL is also related to the number of exposures to potentially leukemogenic agents (i.e., multiple treatments after relapse) and the age of the patient being treated, with those aged >60 years at particularly high risk. The development of carcinomas as a complication of treatment for HL is a major problem. These tumors usually occur ≥10 years after treatment and are associated with use of radiotherapy. For this reason, young women treated with thoracic radiotherapy for HL should institute screening mammograms or breast MRI exams 5–10 years after treatment, and all patients who receive thoracic radiotherapy for HL should be discouraged from smoking. Medias­ tinal radiation also accelerates coronary artery disease, and patients should be encouraged to minimize risk factors for coronary artery disease such as smoking and elevated cholesterol levels. Cervical radiation therapy increases the risk of carotid atherosclerosis and stroke and thyroid disease, including cancer. A number of other late side effects from the treatment of HL are well known. Patients who receive thoracic radiotherapy are at very high risk for the eventual development of hypothyroidism and should be observed for this complication; intermittent mea­ surement of thyrotropin should be made to identify the condition before it becomes symptomatic. Lhermitte’s syndrome occurs in ∼15% of patients who receive thoracic radiotherapy. This syn­ drome is manifested by an “electric shock” sensation into the lower extremities on flexion of the neck. Because of the young age at which HL is often diagnosed, infertility is a concern for patients undergoing treatment for HL. Chemotherapy regimens containing alkylating agents induce permanent infertility in nearly all men. The risk of permanent infertility in women treated with alkylat­ ing agent–containing chemotherapy is age-related, with younger women more likely to recover fertility. Infertility is very rare after treatment with ABVD. NODULAR LYMPHOCYTE-PREDOMINANT HODGKIN’S LYMPHOMA NLPHL is now recognized as an entity distinct from cHL. Previous classification systems recognized that biopsies from a small subset of patients diagnosed as having HL contained a predominance of small lymphocytes and rare Reed-Sternberg–like cells; tumors had a nodular growth pattern and a clinical course that varied from that of patients with cHL. This is an unusual clinical entity and repre­ sents <5% of cases of HL and defines NLPHL. NLPHL has a number of characteristics that suggest its relation­ ship to NHL, rather than cHL, however. The HRS-like cell, or L&H (lymphocyte and histiocyte) or “popcorn” cell, is a clonal prolifera­ tion of B cells that are positive for B-cell markers CD45, CD79a, CD20, CD19, and BCL2. They do not express two markers nor­ mally found on HRS cells, CD30 and CD15. This lymphoma tends to have a chronic, relapsing course and sometimes transforms to diffuse large B-cell lymphoma, including a specific subtype of dif­ fuse large B-cell lymphoma known as T-cell/histiocyte–rich B-cell lymphoma, which shares an immunophenotype with the L&H cell. This natural history most closely resembles that of the indolent B-cell NHLs outlined in Chaps. 113 and 115. Patients with NLPHL are more commonly male (75%). Like cHL, the age distribution of patients with this disease has two peaks, but unlike cHL, these peaks include children and adults age 30–40 years, respectively. The majority of patients diagnosed have stage I or II disease (75%), with a minority having advanced-stage disease at diagnosis. “B” symptoms are uncommon. Patients with early-stage disease at diagnosis should be treated with definitive radiotherapy. This is associated with a 15-year nonrelapse survival rate of 82%. The treatment of patients with advanced-stage NLPHL is controversial. Some clinicians favor no treatment of asymptomatic disease and merely close follow-up, akin to the indolent B-cell NHLs. For patients who need therapy due to symptoms or signs of organ function impairment, both cHL regimens and B-cell NHL regimens have been used, including ABVD and R-CHOP (rituximab, cyclophosphamide, doxorubi­ cin, vincristine, and prednisone). A single-institution experience with R-CHOP resulted in a 100% response rate in a small group of patients without a single relapse with 42 months of follow-up. Although this is short follow-up for an indolent disease, some believe R-CHOP may be curative in this disease and advocate treat­ ing patients with advanced-stage disease at diagnosis, regardless of symptoms or organ function. CHAPTER 115 ■ ■FURTHER READING Ansell SM et al: Overall survival with brentuximab vedotin in stage III or IV Hodgkin’s lymphoma. N Engl J Med 387:310, 2022. Chen R et al: Pembrolizumab in relapsed or refractory Hodgkin lymphoma: 2-year follow-up of KEYNOTE-087. Blood 134:1144, 2019. Gillessen S et al: Intensified treatment of patients with early stage, Less Common Lymphoid and Myeloid Malignancies unfavourable Hodgkin lymphoma: Long-term follow-up of a randomised, international phase 3 trial of the German Hodgkin Study Group (GHSG HD14). Lancet Haematol 8:e278, 2021. Herrera AF et al: Nivolumab+AVD in advanced-stage classic Hodg­ kin’s lymphoma. N Engl J Med 391:1379, 2024. Moskowitz CH et al: Five-year PFS from the AETHERA trial of brentuximab vedotin for Hodgkin lymphoma at high risk of progression or relapse. Blood 132:2639, 2018. Rashidi A et al: Allogeneic hematopoietic stem cell transplantation in Hodgkin lymphoma: A systemic review and meta-analysis. Bone Marrow Transplant 51:521, 2016. Straus DJ et al: CALGB 50604: Risk-adapted treatment of nonbulky early-stage Hodgkin lymphoma based on interim PET. Blood 132: 1013, 2018. Ayalew Tefferi, Dan L. Longo Less Common Lymphoid and Myeloid Malignancies The most common lymphoid malignancies are discussed in Chaps. 111, 112, 113, 114, and 116, myeloid leukemias in Chaps. 109 and 110, myelodysplastic syndromes (MDS) in Chap. 107, and myelopro­ liferative syndromes in Chap. 108. This chapter will focus on the more unusual forms of hematologic malignancy. The diseases discussed here are listed in Table 115-1. Each of these entities accounts for <1% of hematologic neoplasms. RARE LYMPHOID MALIGNANCIES All the lymphoid tumors discussed here are mature B-cell or T-cell natural killer (NK) cell neoplasms. TABLE 115-1  Unusual Lymphoid and Myeloid Malignanciesa Lymphoid Mature B-cell neoplasms   B-cell prolymphocytic leukemia   Splenic marginal zone lymphoma   Hairy cell leukemia   Nodal marginal zone B-cell lymphoma   Mediastinal large B-cell lymphoma   Intravascular large B-cell lymphoma   Primary effusion lymphoma   Lymphomatoid granulomatosis Mature T-cell and natural killer (NK) cell neoplasms   T-cell prolymphocytic leukemia   T-cell large granular lymphocytic leukemia   Aggressive NK cell leukemia   Extranodal NK/T-cell lymphoma, nasal type   Enteropathy-type T-cell lymphoma   Hepatosplenic T-cell lymphoma   Subcutaneous panniculitis-like T-cell lymphoma   Blastic NK cell lymphoma PART 4 Oncology and Hematology   Primary cutaneous CD30+ T-cell lymphoma   Angioimmunoblastic T-cell lymphoma Myeloid Chronic neutrophilic leukemia Chronic eosinophilic leukemia/hypereosinophilic syndrome Histiocytic and Dendritic Cell Neoplasms Histiocytic sarcoma Langerhans cell histiocytosis Langerhans cell sarcoma Interdigitating dendritic cell sarcoma Follicular dendritic cell sarcoma Mast cells Mastocytosis Cutaneous mastocytosis Systemic mastocytosis Mast cell sarcoma Extracutaneous mastocytoma aThis list is not exhaustive. Many named entities are very rare and not discussed here. A complete listing is available in the online version of this chapter. ■ ■MATURE B-CELL NEOPLASMS B-Cell Prolymphocytic Leukemia (B-PLL)  This is a malig­ nancy of medium-sized (about twice the size of a normal small lym­ phocyte), round lymphocytes with a prominent nucleolus and light blue cytoplasm on Wright’s stain. It predominantly affects the blood, bone marrow (BM), and spleen and usually does not cause adenopa­ thy. The median age of affected patients is 70 years, and men are more often affected than women (male-to-female ratio is 1.6). This entity is distinct from chronic lymphoid leukemia (CLL) and does not develop as a consequence of that disease. Clinical presentation is generally from symptoms of splenomegaly or incidental detection of an elevated white blood cell (WBC) count. The clinical course can be rapid. The cells express surface IgM (with or without IgD) and typical B-cell markers (CD19, CD20, CD22). CD23 is absent, and about one-third of cases express CD5. The CD5 expres­ sion along with the presence of the t(11;14) translocation in 20% of cases leads to confusion in distinguishing B-PLL from the leukemic form of mantle cell lymphoma. No reliable criteria for the distinction have emerged, and gene expression studies suggest a close relationship between mantle cell lymphoma and B-PLL and significant differences with CLL. About half of patients have mutation or loss of p53, and deletions have been noted in 11q23 and 13q14. Nucleoside analogues like fludarabine and cladribine and combination chemotherapy (cyclo­ phosphamide, doxorubicin, vincristine, and prednisone [CHOP]) have produced responses. CHOP plus rituximab may be more effective than CHOP alone, but the disease is sufficiently rare that large series have not been reported. Splenectomy can produce palliation of symptoms but appears to have little or no impact on the course of the disease. BM transplantation may be curative. Imatinib may also have activity. Splenic Marginal Zone Lymphoma (SMZL)  This tumor of mainly small lymphocytes originates in the marginal zone of the spleen white pulp, grows to efface the germinal centers and mantle, and invades the red pulp. Splenic hilar nodes, BM, and peripheral blood (PB) may be involved. The circulating tumor cells have short surface villi and are called villous lymphocytes. Table 115-2 shows differences in tumor cells of a number of neoplasms of small lymphocytes that aid in the differential diagnosis. SMZL cells express surface immunoglobu­ lin and CD20 but are negative for CD5, CD10, CD43, and CD103. Lack of CD5 distinguishes SMZL from CLL, and lack of CD103 separates SMZL from hairy cell leukemia. The median age of patients with SMZL is mid-fifties, and men and women are equally represented. Patients present with incidental or symptomatic splenomegaly or incidental detection of lymphocytosis in the PB with villous lymphocytes. Autoimmune anemia or throm­ bocytopenia may be present. The immunoglobulin produced by these cells contains somatic mutations that reflect transit through a germinal center, and ongoing mutations suggest that the mutation machinery has remained active. About 40% of patients have either deletions or translocations involving 7q21, the site of the FLNC gene (filamin Cγ, involved in cross-linking actin filaments in the cytoplasm). NOTCH2 mutations are seen in 25% of patients. Chromosome 8p deletions may also be noted. The genetic lesions typically found in extranodal mar­ ginal zone lymphomas (e.g., trisomy 3 and t[11;18]) are uncommon in SMZL. The clinical course of disease is generally indolent with median sur­ vivals exceeding 10 years. Patients with elevated lactate dehydrogenase (LDH) levels, anemia, and hypoalbuminemia generally have a poorer prognosis. Long remissions can be seen after splenectomy. Rituximab, ibrutinib, and PI3 kinase inhibitors are also active. A small fraction of patients undergo histologic progression to diffuse large B-cell lym­ phoma with a concomitant change to a more aggressive natural history. Experience with combination chemotherapy in SMZL is limited. Hairy Cell Leukemia  Hairy cell leukemia is a tumor of small lymphocytes with oval nuclei, abundant cytoplasm, and distinctive membrane projections (hairy cells). Patients have splenomegaly and diffuse BM involvement. While some circulating cells are noted, the clinical picture is dominated by symptoms from the enlarged spleen and pancytopenia. The mechanism of the pancytopenia is not com­ pletely clear and may be mediated by both inhibitory cytokines and TABLE 115-2  Immunophenotype of Tumors of Small Lymphocytes   CD5 CD20 CD43 CD10 CD103 sIG CYCLIN D1 Follicular lymphoma neg pos pos pos neg pos neg Chronic lymphoid leukemia pos pos pos neg neg pos neg B-cell prolymphocytic leukemia pos pos pos neg neg pos pos Mantle cell lymphoma pos pos pos neg neg pos pos Splenic marginal zone lymphoma neg pos neg neg neg pos neg Hairy cell leukemia neg pos ? neg pos pos neg Abbreviations: neg, negative; pos, positive. TABLE 115-3  Differential Diagnosis of “Dry Tap”—Inability to Aspirate Bone Marrow Dry taps occur in about 4% of attempts and are associated with:   Metastatic carcinoma infiltration 17%   Chronic myeloid leukemia 15%   Myelofibrosis 14%   Hairy cell leukemia 10%   Acute leukemia 10%   Lymphomas, Hodgkin’s disease 9%   Normal marrow Rare marrow replacement. The marrow has an increased level of reticulin fibers; indeed, hairy cell leukemia is a common cause of inability to aspirate BM or so-called “dry tap” (Table 115-3). Monocytopenia is profound and may explain a predisposition to atypical mycobacte­ rial infection that is observed clinically. The tumor cells have strong expression of CD22, CD25, and CD103; soluble CD25 level in serum is an excellent tumor marker for disease activity. The cells also express tartrate-resistant acid phosphatase. The immunoglobulin genes are rearranged and mutated, indicating the influence of a germinal center. No specific cytogenetic abnormality has been found, but most cases contain the activating BRAF mutation V600E. The median age of affected patients is mid-fifties, and the maleto-female ratio is 5:1. Treatment options are numerous. Splenectomy is often associated with prolonged remission. Nucleosides including cladribine and deoxycoformycin are highly active but are also associ­ ated with further immunosuppression and can increase the risk of certain opportunistic infections. However, after brief courses of these agents, patients usually obtain very durable remissions during which immune function spontaneously recovers. Interferon α is also an effective therapy but is not as effective as nucleosides. Chemotherapyrefractory patients have responded to vemurafenib, a BRAF inhibitor. Vemurafenib does not appear to be curative, but responses can be maintained with chronic treatment. More durable remissions occur when rituximab is added to vemurafenib. Nodal Marginal Zone B-Cell Lymphoma  This rare nodebased disease bears an uncertain relationship with extranodal marginal zone lymphomas, which are often mucosa-associated and are called mucosa-associated lymphoid tissue (MALT) lymphomas, and SMZLs. Patients may have localized or generalized adenopathy. The neoplastic cell is a marginal zone B cell with monocytoid features and has been called monocytoid B-cell lymphoma in the past. Up to one-third of the patients may have extranodal involvement, and involvement of the lymph nodes can be secondary to the spread of a mucosal primary lesion. In authentic nodal primaries, the cytogenetic abnormalities associated with MALT lymphomas (trisomy 3 and t[11;18]) are very rare. The clinical course is indolent. Patients often respond to combi­ nation chemotherapy, although remissions have not been durable. Few patients have received CHOP plus rituximab, which is likely to be an effective approach to management. Mediastinal (Thymic) Large B-Cell Lymphoma  This entity was originally considered a subset of diffuse large B-cell lymphoma; however, additional study has identified it as a distinct entity with its own characteristic clinical, genetic, and immunophenotypic features. This is a disease that can be bulky in size but usually remains confined to the mediastinum. It can be locally aggressive, including progressing to produce a superior vena cava obstruction syndrome or pericardial effusion. About one-third of patients develop pleural effusions, and in 5–10% of cases, disease can disseminate widely to kidney, adrenal, liver, skin, and even brain. The disease affects women more often than men (male-to-female ratio is 1:2–3), and the median age is 35–40 years. The tumor is composed of sheets of large cells with abundant cytoplasm accompanied by variable, but often abundant, fibrosis. It is distinguished from nodular sclerosing Hodgkin’s disease by the paucity of normal lymphoid cells and the absence of lacunar variants of Reed-Sternberg cells. However, more than one-third of the genes that are expressed to a greater extent in primary mediastinal large B-cell lymphoma than in usual diffuse large B-cell lymphoma are also overexpressed in Hodgkin’s disease, suggesting a possible pathogenetic relationship between the two entities that affect the same anatomic site. Tumor cells may overexpress MAL. The genome of tumor cells is characterized by frequent chromosomal gains and losses. The tumor cells in mediastinal large B-cell lymphoma express CD20, but surface immunoglobulin and human leukocyte antigen (HLA) class I and class II molecules may be absent or incompletely expressed. Expression of lower levels of class II HLA identifies a subset with poorer prognosis. The cells are CD5 and CD10 negative but may show light staining with anti-CD30. The cells are CD45 positive, unlike cells of classical Hodgkin’s disease. Methotrexate, leucovorin, doxorubicin, cyclophosphamide, vin­ cristine, prednisone, and bleomycin (MACOP-B) and rituximab plus CHOP are effective treatments, achieving 5-year survival of 75–87%. Dose-adjusted therapy with prednisone, etoposide, vincristine, cyclo­ phosphamide, and doxorubicin (EPOCH) plus rituximab has pro­ duced 5-year survival of 97%. A role for mediastinal radiation therapy has not been definitively demonstrated, but it is frequently used, espe­ cially in patients whose mediastinal area remains positron emission tomography–avid after 4–6 cycles of chemotherapy. CHAPTER 115 Intravascular Large B-Cell Lymphoma  This is an extremely rare form of diffuse large B-cell lymphoma characterized by the pres­ ence of lymphoma in the lumen of small vessels, particularly capillaries. It is also known as malignant angioendotheliomatosis or angiotropic large-cell lymphoma. It is sufficiently rare that no consistent picture has emerged to define a clinical syndrome or its epidemiologic and genetic features. It is thought to remain inside vessels because of a defect in adhesion molecules and homing mechanisms, an idea supported by scant data suggesting absence of expression of β-1 integrin and ICAM-1. Patients commonly present with symptoms of small-vessel occlusion, skin lesions, or neurologic symptoms. The tumor cell clusters can promote thrombus formation. A subset of patients have tumors with MYD88 or CD79B mutations. In general, the clinical course is aggres­ sive and the disease is poorly responsive to therapy. Often a diagnosis is not made until very late in the course of the disease or at autopsy. Diagnosis may be revealed in random skin biopsies in settings where localized findings are limited. Less Common Lymphoid and Myeloid Malignancies Primary Effusion Lymphoma  This entity is another variant of diffuse large B-cell lymphoma that presents with pleural effusions, usually without apparent tumor mass lesions. It is most common in the setting of immune deficiency disease, especially AIDS, and is caused by human herpes virus 8 (HHV-8)/Kaposi’s sarcoma herpes virus (KSHV). It is also known as body cavity–based lymphoma. Some patients have been previously diagnosed with Kaposi’s sarcoma. It can also occur in the absence of immunodeficiency in elderly men of Medi­ terranean heritage, similar to Kaposi’s sarcoma but even less common. The malignant effusions contain cells positive for HHV-8/KSHV, and many are also co-infected with Epstein-Barr virus. The cells are large with large nuclei and prominent nucleoli that can be con­ fused with Reed-Sternberg cells. The cells express CD20 and CD79a (immunoglobulin-signaling molecule), although they often do not express immunoglobulin. Some cases aberrantly express T-cell mark­ ers such as CD3 or rearranged T-cell receptor genes. No characteristic genetic lesions have been reported, but gains in chromosome 12 and X material have been seen, similar to other HIV-associated lymphomas. The clinical course is generally characterized by rapid progression and death within 6 months. CHOP plus lenalidomide or bortezomib may produce responses. Highly active antiretroviral therapy for HIV should be maintained during treatment. Lymphomatoid Granulomatosis  This is an angiocentric, angiodestructive lymphoproliferative disease comprised by neoplas­ tic Epstein-Barr virus–infected monoclonal B cells accompanied and outnumbered by a polyclonal reactive T-cell infiltrate. The disease is graded based on histologic features such as cell number and atypia in the B cells. It is most often confused with extranodal NK/T-cell lym­ phoma, nasal type, which can also be angiodestructive and is EpsteinBarr virus–related. The disease usually presents in adults (males > females) as a pulmonary infiltrate. Involvement is often entirely extra­ nodal and can include kidney (32%), liver (29%), skin (25%), and brain (25%). The disease often but not always occurs in the setting of immune deficiency. The disease can be remitting and relapsing in nature or can be rap­ idly progressive. The course is usually predicted by the histologic grade. The disease is highly responsive to combination chemotherapy and is curable in most cases. Some investigators have claimed that low-grade disease (grade I and II) can be treated with interferon α. ■ ■MATURE T-CELL AND NK CELL NEOPLASMS T-Cell Prolymphocytic Leukemia  This is an aggressive leu­ kemia of medium-sized prolymphocytes involving the blood, mar­ row, nodes, liver, spleen, and skin. It accounts for 1–2% of all small lymphocytic leukemias. Most patients present with elevated WBC count (often >100,000/μL), hepatosplenomegaly, and adenopathy. Skin involvement occurs in 20%. The diagnosis is made from PB smear, which shows cells about 25% larger than those in small lymphocytes, with cytoplasmic blebs and nuclei that may be indented. The cells express T-cell markers like CD2, CD3, and CD7; two-thirds of patients have cells that are CD4+ and CD8–, and 25% have cells that are CD4+ and CD8+. T-cell receptor β chains are clonally rearranged. In 80% of patients, inversion of chromosome 14 occurs between q11 and q32. Ten percent have t(14;14) translocations that bring the T-cell receptor alpha/beta gene locus into juxtaposition with oncogenes TCL1 and TCL1b at 14q32.1. Chromosome 8 abnormalities are also common. Deletions in the ATM gene are also noted. Activating JAK3 mutations have also been reported. PART 4 Oncology and Hematology The course of the disease is generally rapid, with median survival of about 12 months. Responses have been seen with the anti-CD52 anti­ body alemtuzumab, nucleoside analogues, and CHOP chemotherapy. Histone deacetylase inhibitors like vorinostat and romidepsin may also have activity. Small numbers of patients with T-cell prolymphocytic leukemia have also been treated with high-dose therapy, and allogeneic BM transplantation after remission has been achieved with alemtu­ zumab or conventional-dose therapy. T-Cell Large Granular Lymphocytic Leukemia  T-cell large granular lymphocytic (LGL) leukemia is characterized by increases in the number of LGLs in the PB (2000–20,000/μL) often accompanied by severe neutropenia, with or without concomitant anemia. Pure red cell aplasia may occur in 15–20% of patients. Splenomegaly is seen in 25% of patients; adenopathy is generally absent. B symptoms are rare, but 20–30% of patients may have infections related to the severe neutropenia. Patients may have splenomegaly and frequently have evi­ dence of systemic autoimmune disease, including rheumatoid arthritis, hypergammaglobulinemia, autoantibodies, and circulating immune complexes. BM involvement is mainly interstitial in pattern, with <50% lymphocytes on differential count. Usually the cells express CD3, T-cell receptors, usually TCRα/β, and CD8; NK-like variants may be CD3–. Like other T-cell neoplasms, loss of expression of CD5 and/or CD7 is common. The leukemic cells often express Fas and Fas ligand. The JAK/STAT pathway is often activated. The course of the disease is generally indolent and dominated by the neutropenia. Paradoxically, immunosuppressive therapy with cyclo­ sporine, methotrexate, or cyclophosphamide plus glucocorticoids can produce an increase in granulocyte counts. Nucleosides have been used anecdotally. Occasionally the disease can accelerate to a more aggres­ sive clinical course. Aggressive NK Cell Leukemia  NK neoplasms are very rare, and they may follow a range of clinical courses from very indolent to highly aggressive. They are more common in Asians than whites, and the cells frequently harbor a clonal Epstein-Barr virus episome. The PB white count is usually not greatly elevated, but abnormal large lymphoid cells with granular cytoplasm are noted. The aggressive form is characterized by symptoms of fever and laboratory abnormalities of pancytopenia. Hepatosplenomegaly is common; node involvement is less common. Patients may have hemophagocytosis, coagulopathy, or multiorgan failure. Serum levels of Fas ligand are elevated. The cells express CD2 and CD56 and do not have rearranged T-cell receptor genes. Deletions involving chromosome 6 are common. The disease can be rapidly progressive. Some forms of NK neoplasms are more indolent. They tend to be discovered incidentally with LGL lymphocytosis and do not manifest the fever and hepatosplenomegaly characteristic of the aggressive leukemia. The cells are also CD2 and CD56 positive, but they do not contain clonal forms of Epstein-Barr virus and are not accompanied by pancytopenia or autoimmune disease. Extranodal NK/T-Cell Lymphoma, Nasal Type  Like lym­ phomatoid granulomatosis, extranodal NK/T-cell lymphoma tends to be an angiocentric and angiodestructive lesion, but the malignant cells are not B cells. In most cases, they are CD56+ Epstein-Barr virus–infected cells; occasionally, they are CD56–Epstein-Barr virus– infected cytotoxic T cells. They are most commonly found in the nasal cavity. Historically, this illness was called lethal midline granuloma, polymorphic reticulosis, and angiocentric immunoproliferative lesion. This form of lymphoma is prevalent in Asia, Mexico, and Central and South America; it affects males more commonly than females. When it spreads beyond the nasal cavity, it may affect soft tissue, the gastro­ intestinal tract, or the testis. In some cases, hemophagocytic syndrome (HPS) may influence the clinical picture. Patients may have B symp­ toms. Many of the systemic manifestations of disease are related to the production of cytokines by the tumor cells and the cells responding to their signals. Deletions and inversions of chromosome 6 are common. Many patients with extranodal NK/T-cell lymphoma, nasal type, have excellent antitumor responses with combination chemotherapy regimens, particularly those with localized disease. Radiation therapy is often used after completion of chemotherapy. Four risk factors have been defined, including B symptoms, advanced stage, elevated LDH, and regional lymph node involvement. Patient survival is linked to the number of risk factors: 5-year survival is 81% for zero risk factors, 64% for one risk factor, 32% for two risk factors, and 7% for three or four risk factors. Combination regimens without anthracyclines have been touted as superior to CHOP, but data are sparse. High-dose therapy with stem cell transplantation has been used, but its role is unclear. Enteropathy-Type T-Cell Lymphoma  Enteropathy-type T-cell lymphoma is a rare complication of longstanding celiac disease. It most commonly occurs in the jejunum or the ileum. In adults, the lymphoma may be diagnosed at the same time as celiac disease, but the suspicion is that the celiac disease was a longstanding precursor to the develop­ ment of lymphoma. The tumor usually presents as multiple ulcerating mucosal masses but may also produce a dominant exophytic mass or multiple ulcerations. The tumor expresses CD3 and CD7 nearly always and may or may not express CD8. The tumor may express CD30, but therapies directed at CD30 have not been adequately tested. The normal-appearing lymphocytes in the adjacent mucosa often have a similar phenotype to the tumor. Most patients have the HLA genotype associated with celiac disease, HLA DQA1∗0501 or DQB1∗0201. The prognosis of this form of lymphoma is typically poor (median survival is 7–11 months), but some patients have a good response to CHOP chemotherapy. Patients who respond can develop bowel per­ foration from responding tumor. If the tumor responds to treatment, recurrence may develop elsewhere in the celiac disease–affected small bowel. An indolent form of T-cell or NK cell lymphoma occurs rarely that affects mainly the small intestine and presents with dyspepsia, vomit­ ing, and diarrhea. The cells often contain genetic changes that result in JAK-STAT activation. The disease is most often chronic with little or no propensity to spread and develop aggressive growth. A variety of approaches have been tested; none are reliably curative. Hepatosplenic T-Cell Lymphoma  Hepatosplenic T-cell lym­ phoma is a malignancy derived from T cells expressing the gamma/delta T-cell antigen receptor that affects mainly the liver and fills the sinu­ soids with medium-size lymphoid cells. When the spleen is involved, dominantly the red pulp is infiltrated. It is a disease of young people, especially young people with an underlying immunodeficiency or with an autoimmune disease that demands immunosuppressive therapy. The use of thiopurine and infliximab is particularly common in the history of patients with this disease. The cells are CD3+ and usually CD4– and CD8–. The cells may contain isochromosome 7q, often together with trisomy 8. The lymphoma has an aggressive natural history. Combination chemotherapy may induce remissions, but most patients relapse. Cytarabine/etoposide/platinum-based regimens appear more effective than CHOP-based regimens. Median survival is about 2 years. The tumor does not appear to respond to reversal of immunosuppressive therapy. Subcutaneous Panniculitis-Like T-Cell Lymphoma  Subcutaneous panniculitis-like T-cell lymphoma involves multiple subcutaneous collections of neoplastic T cells that are usually cytotoxic cells in phenotype (i.e., contain perforin and granzyme B and express CD3 and CD8). The rearranged T-cell receptor is usually alpha/betaderived, but occasionally, the gamma/delta receptors are involved, par­ ticularly in the setting of immunosuppression. The cells are negative for Epstein-Barr virus. A history of autoimmune disease, particularly lupus erythematosus, in the patient or the family is present in almost one-third of patients. Patients may have an HPS in addition to the skin infiltration; fever and hepatosplenomegaly may also be present. Nodes are generally not involved. Patients frequently respond to combination chemotherapy, including CHOP. When the disease is progressive, the HPS can be a component of a fulminant downhill course. Effective therapy can reverse the HPS. Blastic NK Cell Lymphoma  The neoplastic cells express NK cell markers, especially CD56, and are CD3 negative. They are large blasticappearing cells and may produce a leukemia picture, but the dominant site of involvement is the skin. Morphologically, the cells are similar to the neoplastic cells in acute lymphoid and myeloid leukemia. No characteristic chromosomal abnormalities have been described. The clinical course is rapid, and the disease is largely unresponsive to typi­ cal lymphoma treatments. Primary Cutaneous CD30+ T-Cell Lymphoma  This tumor involves the skin and is composed of cells that appear similar to the cells of anaplastic T-cell lymphoma. Among cutaneous T-cell tumors, ~25% are CD30+ anaplastic lymphomas. If dissemination to lymph nodes occurs, it is difficult to distinguish between the cutaneous and systemic forms of the disease. The tumor cells are often CD4+, and the cells contain granules that are positive for granzyme B and perforin in 70% of cases. The typical t(2;5) of anaplastic T-cell lymphoma is absent; indeed, its presence should prompt a closer look for systemic involvement and a switch to a diagnosis of anaplastic T-cell lymphoma. This form of lymphoma has sporadically been noted as a rare com­ plication of silicone or saline breast implants. The natural history of breast implant–associated lymphoma is generally indolent. Cutaneous CD30+ T-cell lymphoma often responds to therapy. The anti-CD30 immunotoxin conjugate brentuximab vedotin is active. Radiation therapy can be effective, and surgery can also produce long-term dis­ ease control. Five-year survival exceeds 90%. Angioimmunoblastic T-Cell Lymphoma  Angioimmunoblastic T-cell lymphoma is a systemic disease that accounts for ~15% of all T-cell lymphomas. Patients frequently have fever, advanced stage, dif­ fuse adenopathy, hepatosplenomegaly, skin rash, polyclonal hypergam­ maglobulinemia, and a wide range of autoantibodies including cold agglutinins, rheumatoid factor, and circulating immune complexes. Patients may have edema, arthritis, pleural effusions, and ascites. The nodes contain a polymorphous infiltrate of neoplastic T cells and non­ neoplastic inflammatory cells together with proliferation of high endo­ thelial venules and follicular dendritic cells (FDCs). The most common chromosomal abnormalities are trisomy 3, trisomy 5, and an extra X chromosome. Aggressive combination chemotherapy can induce regressions. The underlying immune defects make conventional lym­ phoma treatments more likely to produce infectious complications. RARE MYELOID MALIGNANCIES The World Health Organization (WHO) and the International Consensus Classification (ICC) systems use PB counts, PB smear analysis, BM mor­ phology, and cytogenetic and molecular genetic tests in order to classify myeloid malignancies into several major categories (Table 115-4). Among them, acute myeloid leukemia (AML) and AML-related disorders are discussed in Chap. 109, MDS and MDS/AML in Chap. 107, chronic myeloid leukemia (CML) in Chap. 110, and JAK2 mutation–prevalent myeloproliferative neoplasms (MPN), including essential thrombocy­ themia, polycythemia vera, and primary myelofibrosis, in Chap. 108. In this chapter, we focus on some of the remaining myeloid neoplasms listed in Table 115-4, which are less frequent: (1) other MPNs includ­ ing chronic neutrophilic leukemia (CNL), chronic eosinophilic leu­ kemia, not otherwise specified (CEL-NOS), and MPN, unclassifiable (MPN-U); (2) MDS/MPN overlap including chronic myelomonocytic leukemia (CMML), atypical CML (aCML), MDS/MPN with mutated SF3B1 and thrombocytosis, MDS/MPN with ring sideroblasts and thrombocytosis, not otherwise specified (MDS/MPN-RS-T-NOS), and MDS/MPN, not otherwise specified (MDS/MPN-NOS); (3) juvenile myelomonocytic leukemia (JMML); (4) transient myeloproliferative disorder (TMD); (5) hypereosinophilia including those associated with tyrosine kinase gene fusions (TKGFs) and hypereosinophilic syn­ drome (HES); (6) mastocytosis; and (7) histiocytic and dendritic cell neoplasms (hemophagocytic lymphohistiocytosis [HLH] is discussed in Chap. 68). CHAPTER 115 Less Common Lymphoid and Myeloid Malignancies ■ ■CHRONIC NEUTROPHILIC LEUKEMIA CNL is a clonal proliferation of mature neutrophils with few or no circulating immature granulocytes. Other clinical features include hepatosplenomegaly and constitutional symptoms. The disease is molecularly characterized by activating mutations of the gene (CSF3R) encoding for the receptor for granulocyte colony-stimulating factor (G-CSF), also known as colony-stimulating factor 3 (CSF3). Patients with CNL might be asymptomatic at presentation but can also display constitutional symptoms, splenomegaly, anemia, and thrombocytope­ nia. A population-based study suggested an overall incidence of 0.1 cases/million individuals, using combined Surveillance, Epidemiology, and End Results and National Cancer Database data. CNL typically presents in elderly patients with a median age at diagnosis of 66.5 years (range, 15–86 years) and slight male preponderance (56–58% of cases). Median survival is ~2 years, and causes of death include transforma­ tion to acute leukemia, progressive disease associated with severe cyto­ penias, and marked treatment-refractory leukocytosis. CSF3 is the main growth factor for granulocyte proliferation and differentiation. Accordingly, recombinant CSF3 is used for the treat­ ment of severe neutropenia, including severe congenital neutropenia (SCN). Some patients with SCN acquire CSF3R mutations, and the frequency of such mutations is significantly higher (~80%) in patients who experience leukemic transformation. SCN-associated CSF3R mutations occur in the region of the gene coding for the cytoplasmic domain of CSF3R and result in truncation of the C-terminal–negative regulatory domain. In 2013, Maxson et al described a different class of CSF3R mutations in ~90% of patients with CNL; these were mostly membrane proximal, the most frequent being a C-to-T substitution at nucleotide 1853 (T618I). In a subsequent confirmatory study, CSF3R mutations were found to be specific to WHO-defined CNL. About 40% of the T618I-mutated cases also harbored SETBP1 mutations. CSF3R T618I has been shown to induce lethal myeloproliferative disorder in a mouse model and to have in vitro sensitivity to JAK inhibition. Diagnosis of CNL requires exclusion of the more common causes of neutrophilia including infections and inflammatory processes (Table 115-5). In addition, one should be mindful of the association between some forms of metastatic cancer or plasma cell neoplasms with secondary neutrophilia. Neoplastic neutrophilia also occurs in other myeloid malignancies, which should be excluded during the TABLE 115-4  International Consensus Classification of Myeloid Neoplasms 6. Acute myeloid leukemia (AML) a. AML diagnosis requiring ≥10% bone marrow (BM) or peripheral blood (PB) blasts i. Acute promyelocytic leukemia ii. Core binding factor AML iii. AML with KMT2A rearrangement iv. AML with DEK::NUP214 v. AML with MECOM rearrangements vi. AML with NPM1 mutation vii. AML with in-frame bZIP CEBPA mutations viii. AML with other rare recurring translocations ix. Myelodysplastic syndrome (MDS)/AML with TP53 mutations x. MDS/AML with myelodysplasia-related mutations xi. MDS/AML with myelodysplasia-related karyotype xii. MDS/AML not otherwise specified (NOS) b. AML diagnosis requiring ≥20% BM or PB blasts i. AML with t(9;22)-BCR::ABL1 ii. AML with TP53 mutations, other than pure erythroid leukemia iii. AML with myelodysplasia-related gene mutations iv. AML with myelodysplasia-related karyotype v. AML NOS 7. AML-related disorders PART 4 Oncology and Hematology a. Pure erythroid leukemia (PEL; TP53 mutated) b. Myeloid sarcoma c. Blastic plasmacytoid dendritic cell neoplasm d. Acute leukemia of ambiguous lineage e. Acute undifferentiated leukemia f. Mixed phenotype acute leukemia 8. Myelodysplastic syndromes (MDS) a. MDS with mutated TP53 b. MDS with excess blasts (5–9% BM or 2–9% PB) c. MDS without excess blasts (<5% BM and <2% PB) i. MDS with del(5q) [isolated or accompanied by only one other cytogenetic abnormality other than 7/del(7q); no multi-hit TP53] ii. MDS with SF3B1 [variant allele frequency ≥10%/no RUNX1 or multi-hit TP53; no del(5q), –7/del(7q), complex karyotype, or abnormal 3q26.2] iii. MDS, NOS–single-lineage dysplasia iv. MDS, NOS–multilineage dysplasia v. MDS, NOS without dysplasia 9. MDS/AML a. MDS/AML (BM/PB blasts 10–19%) b. MDS/AML with mutated TP53 10. Myeloproliferative neoplasms (MPN) a. Chronic myeloid leukemia b. Polycythemia vera c. Essential thrombocythemia d. Primary myelofibrosis (PMF) i. Early/prefibrotic PMF ii. Overt PMF e. MPN, unclassifiable (MPN-U) f. Chronic neutrophilic leukemia g. Chronic eosinophilic leukemia, NOS 11. MDS/MPN a. Chronic myelomonocytic leukemia (CMML) (≥0.5 × 109/L absolute and ≥10% PB monocytes) i. CMML-1 (<10% BM and <5% PB blasts) ii. CMML-2 (10–19% BM or 5–19% PB blasts) b. Atypical chronic myeloid leukemia c. MDS/MPN with mutated SF3B1 and thrombocytosis d. MDS/MPN with ring sideroblasts and thrombocytosis, NOS e. MDS/MPN, NOS i. MDS/MPN with isolated isochromosome (17q) 12. Eosinophilic disorders 13. Mastocytosis 14. Hematologic neoplasms with germline predisposition 15. Pediatric myeloid malignancies 16. Premalignant clonal hematopoiesis diagnostic workup (Table 115-5). Accordingly, the ICC diagnostic crite­ ria for CNL are designed to exclude the possibilities of both secondary/ reactive neutrophilia and leukocytosis associated with myeloid malig­ nancies other than CNL (Table 115-5). The discovery of CSF3R mutations (see above) and their almost invariable association with ICC-defined CNL has allowed its incorporation in the ICC diagnostic criteria (Table 115-5). In general, the presence of a membrane proxi­ mal CSF3R mutation in a patient with predominantly neutrophilic granulocytosis should be sufficient for the diagnosis of CNL, regard­ less of the degree of leukocytosis. Unfortunately, several exclusionary criteria still need to be met for diagnosing CNL in the absence of CSF3R mutations (Table 115-5). Current treatment in CNL is largely palliative and suboptimal in its efficacy. Several drugs alone or in combination have been tried, and none have shown remarkable efficacy. As such, allogeneic hema­ topoietic stem cell transplant (ASCT) is reasonable to consider in the presence of symptomatic disease, especially in younger patients. Oth­ erwise, cytoreductive therapy with hydroxyurea is probably as good as anything, and a more intensive combination chemotherapy may not have additional value. However, response to hydroxyurea therapy is often transient, and some have successfully used interferon α as an alternative drug. JAK inhibitor therapy has emerged as an additional therapeutic option but is not necessarily superior to hydroxyurea (estimated response rate of 30%). It is thus recommended that CNL patients first and foremost be evaluated for eligibility and disposition for ASCT, with the remaining therapeutic agents being aimed at con­ trolling myeloproliferation (targeting leukocytes <25–30 × 109/L) and alleviating symptoms. ■ ■CHRONIC EOSINOPHILIC LEUKEMIA, NOT OTHERWISE SPECIFIED In a Mayo Clinic survey of 1416 patients with PB eosinophilia evalu­ ated between 2008 and 2019, 17 patients (1.2%) fulfilled the ICC crite­ ria for CEL-NOS (Table 115-5); median age was 63 years, with the vast majority of patients (88%) presenting with systemic symptoms. Organ involvement was a prominent feature including spleen, cardiac, pulmo­ nary, and distal esophagus. Laboratory abnormalities included anemia, leukocytosis, and eosinophilia (median eosinophil count of 6.4 × 109/L; range, 2.0–53.1 × 109/L). The most common bone marrow abnormali­ ties included abnormal eosinophils, abnormal and increased mega­ karyocytes, and fibrosis (18%). Cytogenetic abnormalities occurred in 88% of patients and included trisomy 8, complex karyotype, 13q–, 20q–, and chromosome 1 abnormalities. All seven patients with next-generation sequencing studies harbored one or more mutations including ASXL1 (43%) and IDH1 (29%). Half of patients treated with hydroxyurea-based regimens responded with a persistent decline in eosinophil count for a median duration of 18 months. One-third of patients treated with prednisone responded, with a median duration of response at 13 months. Three patients were treated with imatinib, of whom two had normalization of eosinophil count. At a median follow-up of 13 months, nine patients had died, including three who underwent leukemic transformation. ■ ■MYELOPROLIFERATIVE NEOPLASM, UNCLASSIFIABLE The category of MPN-U includes MPN-like neoplasms that cannot be clearly classified as one of the other subcategories of MPN listed in Table 115-1. Examples include patients presenting with unusual thrombosis or unexplained organomegaly with normal blood counts but found to carry MPN-characteristic mutations such as JAK2 and CALR or display bone marrow morphology that is consistent with MPN. It is possible that some cases of MPN-U represent earlier disease stages in polycythemia vera (PV) or essential thrombocythemia (ET), which, however, fail to meet the threshold hemoglobin levels or platelet counts that are required per WHO diagnostic criteria. Specific treat­ ment interventions might not be necessary in asymptomatic patients with MPN-U, whereas patients with arterial thrombotic complications might require cytoreductive and aspirin therapy and those with venous thrombosis might require systemic anticoagulation. TABLE 115-5  International Consensus Classification (ICC) Diagnostic Criteria for Chronic Neutrophilic Leukemia (CNL), Atypical Chronic Myeloid Leukemia (aCML), and Chronic Myelomonocytic Leukemia (CMML) VARIABLES CNLa aCML CMML PB leukocyte count ≥13 × 109/Ld ≥13 × 109/L   PB segmented neutrophils/bands ≥80%     PB neutrophil precursorsb <10% ≥10%   PB blasts Usually absente <20% <20% PB monocyte count <10% of leukocytes No or minimal monocytosis ≥0.5 × 109/Lg Cytopeniah   Yes Yes Dysgranulopoiesis   Yes   PB basophil/eosinophil percentage   <10%   PB monocyte percentage   <10% ≥10% BM Hypercellular ↑ Neutrophils, number and % <5% blasts Normal neutrophilic maturation   BCR-ABL1 No No No Tyrosine kinase gene fusionsf No No No CSF3R T618I or other activating CSF3R mutation or persistent neutrophilia, splenomegaly, no identifiable cause of reactive neutrophilia,c if plasma cell neoplasm is present, need demonstration of clonality of myeloid cells by cytogenetic or molecular studies Yes     PB and BM blasts/promonocytes   <20% <20% Evidence for other MPN: CML, PV, ET, PMF No No No Evidence for reactive leukocytosis or monocytosis No No No aDiagnosis requires meeting all criteria. bNeutrophil precursors include myeloblasts, promyelocytes, myelocytes, and metamyelocytes. cCauses of reactive neutrophilia include plasma cell neoplasms, solid tumor, infections, and inflammatory processes. d≥25 × 109/L in cases lacking CSF3R T618I or another activating CSF3R mutation. e10–19% blasts constitute accelerated phase and ≥20% blast phase. fTyrosine kinase gene fusions involve PDGFRA, PDGFRB, FGFR1, ABL1, JAK2, and FLT3. gPB monocytes ≥1 × 109/L in cases without evidence of clonality; the latter is signified by abnormal karyotype or a myeloid neoplasm associated mutation with ≥10% variant allele frequency. hHemoglobin <12 g/dL in females and <13 g/dL in males, absolute neutrophil count <1.8 × 109/L, and/or platelets <150 × 109/L, that is not explained by another condition. Abbreviations: AML, acute myeloid leukemia; BM, bone marrow; CML, chronic myeloid leukemia; ET, essential thrombocythemia; MDS, myelodysplastic syndromes; MPN, myeloproliferative neoplasms; PB, peripheral blood; PMF, primary myelofibrosis; PV, polycythemia vera. ■ ■CHRONIC MYELOMONOCYTIC LEUKEMIA CMML is classified under the ICC category of MDS/MPN neoplasms and is defined by sustained (>3 months) PB monocytosis (≥0.5 × 109/L; monocytes ≥10% of leukocyte count), consistent BM morphology, <20% BM or PB blasts (including promonocytes), and cytogenetic or molecular evidence of clonality. The median age at CMML diagno­ sis is ~73–75 years, with a male preponderance (1.5–3:1). The exact incidence of CMML remains unknown but is estimated at 4 cases per 100,000 persons per year. Clinical presentation is variable and depends on whether the disease presents with MDS-like (MDS-CMML) or MPN-like (MP-CMML) phenotype, based on the presence or absence of leukocyte count of ≥13 × 109/L; the former is associated with cyto­ penias and the latter with splenomegaly and features of myeloprolif­ eration such as fatigue, night sweats, weight loss, and cachexia. About 20% of patients with CMML experience unique symptoms including systemic inflammatory syndromes (e.g., arthritis, pericardial effusion, pleural effusion, ascites), autoimmune diseases, leukemia cutis, and lysozyme-induced nephropathy. During the diagnostic workup of CMML, it is important to first exclude reactive causes of monocytosis, including tuberculosis, fungal infections, subacute bacterial endocarditis, viral and protozoal infec­ tions, connective tissue diseases, sarcoidosis, lipid storage disorders, postsplenectomy state, and the recovery phase of an acute infection or BM regeneration after chemotherapy. Other myeloid neoplasms in the differential diagnosis include CML (BCR::ABL1-defined) and other fusion gene-associated entities including those with rearrangements of PDGFRA, PDGFRB, FGFR1, JAK2, FLT3, and ABL1. Similarly, it Persistent and lasting for at least 3 months Hypercellular ↑ Granulocyte proliferation Granulocytic dysplasia ± erythroid/megakaryocyte Dysplasia <20% blasts  Hypercellular due to myeloproliferation and increased monocytes and lacking diagnostic features of AML, MPN, or other conditions associated with monocytosis  CHAPTER 115 Less Common Lymphoid and Myeloid Malignancies should be noted that monocytosis can be associated with MPN such as primary myelofibrosis (PMF) and PV, where its presence adversely impacts survival. BM examination often shows morphologic dysplasia in at least one hematopoietic lineage and granulocytic and monocytic proliferation. On immunophenotyping, the abnormal cells often express myelomonocytic antigens such as CD13 and CD33, with variable expression of CD14, CD64, CD68, and CD163. Monocyticderived cells are almost always positive for the cytochemical non­ specific esterases (e.g., butyrate esterase), while normal granulocytic precursors are positive for lysozyme and chloroacetate esterase. In CMML, it is common to have a hybrid cytochemical staining pattern with cells expressing both chloroacetate and butyrate esterases simul­ taneously (dual esterase staining). Based on flow cytometric expression of CD14/CD16, monocytes can be classified into classical MO1 (CD14+/CD16–), intermediate MO2 (CD14+/CD16+), and nonclassical MO3 (CD14−/CD16+) frac­ tions, with MO1 constituting the major monocyte population (85%) in healthy conditions. CMML patients have a characteristic increase in classical monocytes, distinguishing CMML from other causes of reactive and clonal monocytosis. Almost all patients with CMML har­ bor somatic mutations that are neither specific nor disease-defining, including (1) mutations in epigenetic control of transcription, such as histone modification (EZH2, ASXL1, UTX), and DNA methylation (TET2, DNMT3A, IDH1, IDH2); (2) mutations in the spliceosome machinery (SF3B1, SRSF2, U2AF1, ZRSR2, PRPF8); (3) mutations in genes that regulate cell signaling (JAK2, KRAS, NRAS, CBL, PTPN11, NF1, FLT3); (4) mutations in transcription factors and nucleosome assembly regulators (RUNX1, GATA2, SETBP1); and (5) mutations in DNA damage response genes such as TP53 and PHF6. Of these, those involving TET2 (~60%), SRSF2 (~50%), ASXL1 (~40%), and the oncogenic RAS pathway (~30%) are the most frequent, with only frameshift and nonsense ASXL1 mutations consistently and indepen­ dently adversely impacting survival. Clonal cytogenetic abnormalities are seen in about a third of patients with CMML and include trisomy 8 and abnormalities of chromosome 7. Several risk models serve similar purposes in identifying high-risk patients who are considered for ASCT earlier than later. Risk factors in the Mayo Molecular Model (MMM) include presence of truncating ASXL1 mutations, absolute monocyte count >10 × 109/L, hemoglobin <10 g/dL, platelet count <100 × 109/L, and the presence of circulating immature myeloid cells. The resulting four-tiered risk categorization includes high (three or more risk factors), intermediate-2 (two risk factors), intermediate-1 (one risk factor), and low (no risk factors); the corresponding median survivals are 16, 31, 59, and 97 months, respectively. ASCT is the only treatment modality that secures cure or long-term survival and is appropriate for MMM high/intermediate-2 risk disease. In one of the largest retrospective cohorts involving 513 CMML patients (median age, 53 years), the European Group for Blood and Marrow Transplantation reported a 4-year relapse-free survival rate of 27% and an overall survival rate of 33%. At present, for younger patients with higher risk disease and an acceptable comorbidity index, ASCT is the preferred treatment modality. Drug therapy is currently not disease-modifying and includes hydroxyurea and hypomethylat­ ing agents; a phase 3 study (DAKOTA) comparing hydroxyurea and decitabine in high-risk MP-CMML showed similar overall survival at 23.1 versus 18.4 months, respectively, despite response rates being higher for decitabine (56 vs 31%). PART 4 Oncology and Hematology ■ ■ATYPICAL CHRONIC MYELOID LEUKEMIA aCML is formally classified under the MDS/MPN category of myeloid malignancies and is characterized by left-shifted granulocytosis and dysgranulopoiesis. Diagnostic criteria are listed in Table 115-2 and include leukocyte count of ≥13 × 109/L, dysgranulopoiesis, cytopenia, ≥10% immature granulocytes, <20% PB or BM myeloblasts, <10% PB monocytes, <10% PB eosinophilia, absence of otherwise specific mutations such as BCR::ABL1 or TKGFs (involving PDGFRA, PDG­ FRB, FGFR1, JAK2, ABL1, or FLT3; Table 115-6), and not meeting WHO criteria for CML, PMF, PV, or ET. The BM in aCML is hyper­ cellular with granulocyte proliferation and dysplasia with or without erythroid or megakaryocytic dysplasia. The differential diagnosis of aCML includes CML, which is distinguished by the presence of BCR::ABL1; CNL, which is distinguished by the absence of dysgranu­ lopoiesis and presence of CSF3R mutations; and CMML, which is distinguished by the presence of monocytosis (absolute monocyte count ≥0.5 × 109/L). TABLE 115-6  Primary Eosinophilia Classification EOSINOPHILIA ASSOCIATED WITH TKGF (M/LN-EO-TK) VARIABLES Absolute eosinophil count ≥1500 × 109/L ≥1500 × 109/L ≥1500 × 109/L ≥1500 × 109/L PB eosinophil % ≥10% ≥10% ≥10% ≥10% Documentation of chronicity of eosinophilia Advised Advised Advised Advised Comorbidity associated with secondary eosinophilia Absent Absent Absent Absent PB blast ≥2% or BM blast ≥5% Yes or no Yes or no No No Abnormal karyotype Yes or no Yes or no No No TKGF Yes No No No BCR-ABL1 No No No No Abnormal T lymphocyte phenotype or clonal T-cell clones No No Yes No Eosinophil-mediated tissue/organ damage Yes or no Yes or no Yes or no Yes Abbreviations: ABL1 (e.g., ETV6::ABL1); BM, bone marrow; FGFR1 (e.g., ZMYM2::FGFR1); FLT3 (ETV6::FLT3); JAK2 (PCM1::JAK2); M/LN-eo-TK, myeloid/lymphoid neoplasms with eosinophilia and TKGF; PB, peripheral blood; TKGF, tyrosine kinase gene fusions, often involving PDGFRA (e.g. FIP1L1::PDGFRA) or PDGFRB (e.g., ETV6::PDGFRB). The molecular pathogenesis of aCML is incompletely understood; about one-fourth of patients express SETBP1 mutations, which are, however, also found in several other myeloid malignancies, including CNL and CMML. SETBP1 mutations in aCML were prognostically detrimental and mostly located between codons 858 and 871; similar mutations are seen with Schinzel-Giedion syndrome (a congenital disease with severe developmental delay and various physical stigmata including midface retraction, large forehead, and macroglossia). A somatic missense mutation in ethanolamine kinase 1 (ETNK1 N244S) was described in 9% of patients with aCML but was also seen in 14% of patients with CMML, 6% of patients with mastocytosis (especially in association with eosinophilia), and rarely in other MPNs. In a series of 55 patients with WHO-defined aCML, median age at diagnosis was 62 years, with female preponderance (57%); sple­ nomegaly was reported in 54% of the patients, red cell transfusion requirement in 65%, abnormal karyotype in 20% (20q– and trisomy 8 being the most frequent), and leukemic transformation in 40%. Median survival was 25 months. Outcome was worse in patients with marked leukocytosis, transfusion requirement, and increased imma­ ture cells in the PB. In a more recent Mayo Clinic study of 25 molecu­ larly annotated and strictly WHO-defined aCML patients, median age was 70 years and 84% were male. Cytogenetic abnormalities were seen in 36% and gene mutations in 100%. Mutational frequencies were as follows: ASXL1 28%, TET2 16%, NRAS 16%, SETBP1 12%, RUNX1 12%, ETNK1 8%, and PTPN11 4%. Median survival was 10.8 months, and at last follow-up (median, 11 months), 17 (68%) deaths and 2 (8%) leukemic transformations were documented. In multivariable analysis, advanced age, low hemoglobin, and TET2 mutations were shown to carry independent prognostic significance; other mutations, includ­ ing ASXL1 and SETBP1 lacked prognostic significance. Conventional chemotherapy is largely ineffective in the treatment of aCML. Similarly, treatment response to the JAK1/2 inhibitor ruxolitinib has not been impressive. However, a favorable experience with ASCT was reported in nine patients; after a median follow-up of 55 months, the majority of the patients remained in complete remission. ■ ■MDS/MPN WITH MUTATED SF3B1 OR WITH RING SIDEROBLASTS, BOTH ASSOCIATED WITH THROMBOCYTOSIS OR NOT OTHERWISE SPECIFIED The ICC classifies patients with morphologic and laboratory features that resemble both MDS and MPN as “MDS/MPN overlap.” This cat­ egory is broad and is distinguished from MPN by the presence of “cyto­ penia.” Leukocytosis is also part of the definition for the subcategories of MDS/MPN, including MDS/MPN with mutated SF3B1 (MDS/ MPN-T-SF3B1), MDS/MPN with ring sideroblasts and thrombocyto­ sis, NOS (MDS/MPN-RS-T-NOS), and MDS/MPN-NOS. Diagnostic criteria for MDS/MPN-T-SF3B1 include thrombocytosis (≥450 × 109/L), anemia, blasts <1% in PB and <5% in BM, presence of SF3B1 CHRONIC EOSINOPHILIC LEUKEMIA, NOT OTHERWISE SPECIFIED (CEL-NOS) LYMPHOCYTIC VARIANT HYPEREOSINOPHILIA HYPEREOSINOPHILIC SYNDROME (variant allele frequency [VAF] >10%), and not otherwise classified as another myeloid neoplasm; corresponding criteria for MDS/MPN-RST-NOS also include thrombocytosis and anemia and absence of excess blasts but, in addition, require presence of ≥15% BM ring sideroblasts and absence of SF3B1 mutation. The term MDS/MPN-NOS is reserved for MDS/MPN that does not meet criteria for either of the aforemen­ tioned MDS/MPN entities despite displaying thrombocytosis (≥450 × 109/L) or leukocytosis (≥13 × 109/L). ■ ■JUVENILE MYELOMONOCYTIC LEUKEMIA JMML is primarily a disease of early childhood and is now considered a unique clonal disorder of childhood, separated from MDS/MPN. Both CMML and JMML feature leukocytosis, monocytosis, and hepa­ tosplenomegaly. Additional characteristic features in JMML include thrombocytopenia and elevated fetal hemoglobin. Myeloid progenitors in JMML display granulocyte-macrophage colony-stimulating factor (GM-CSF) hypersensitivity that has been attributed to dysregulated RAS/MAPK signaling. The latter is believed to result from mutually exclusive mutations involving RAS, PTPN11, and NF1. A third of patients with JMML that is not associated with Noonan syndrome carry PTPN11 mutations, while the incidence of NF1 in patients without neurofibromatosis type 1 and RAS mutations is ~15% each. In general, ~85% of JMML cases have one of the classical RAS pathway mutations (PTPN11, NRAS, KRAS, NF1, or CBL); in addition, a myriad of other mutations, such as ASXL1, RUNX1, SETBP1, JAK3, and CUX1, among others, have recently been reported. Taken together, it is cur­ rently believed that almost all patients with JMML harbor mutations in the RAS pathway; clonal disorders that mimic JMML but do not harbor a RAS pathway mutation are classified as JMML-like neoplasms. The 2022 ICC diagnostic criteria for JMML require the presence of PB monocyte count ≥1 × 109/L, <20% blasts in PB or BM, splenomeg­ aly, and absence of BCR::ABL1. Diagnosis also requires the presence of one of the following: (1) somatic mutations of PTPN11, KRAS, NRAS, or RRAS; (2) germline NF1 mutation and loss of heterozygosity of NF1 or clinical diagnosis of neurofibromatosis type 1; and (3) germline mutation and loss of heterozygosity of CBL. Drug therapy is relatively ineffective in JMML, and the treatment of choice is ASCT, which results in a 5-year survival of ~50%. ■ ■TRANSIENT MYELOPROLIFERATIVE DISORDER TMD, also referred to as transient abnormal myelopoiesis (TAM), constitutes an often but not always transient phenomenon of abnor­ mal megakaryoblast proliferation, which occurs in ~10% of infants with Down syndrome. TMD is usually recognized at birth and either undergoes spontaneous regression (75% of cases) or progresses to acute megakaryoblastic leukemia (AMKL; 25% of cases). Almost all patients with TMD and TMD-derived AMKL display somatic GATA1 muta­ tions. TMD-associated GATA1 mutations constitute exon 2 insertions, deletions, or missense mutations, affecting the N-terminal transactiva­ tion domain of GATA-1 and resulting in loss of full-length (50 kD) GATA-1 and its replacement with a shorter isoform (40 kD) that retains friend of GATA-1 (FOG-1) binding. In contrast, inherited forms of exon 2 GATA1 mutations produce a phenotype with anemia, whereas exon 4 mutations that affect the N-terminal, FOG-1-interactive domain produce familial dyserythropoietic anemia with thrombocytopenia or X-linked macrothrombocytopenia. ■ ■HYPEREOSINOPHILIA Eosinophilia refers to a PB absolute eosinophil count (AEC) that is above the upper normal limit of the reference range. The term hype­ reosinophilia (HE) is used when the AEC is ≥1500 × 109/L. The ICC recommends both BM and PB examination for diagnostic evaluation of HE. The former should include cytogenetic and molecular analysis as well as immunohistochemistry for mast cells (CD117, tryptase, CD25), and the latter should include lymphocyte flow cytometry with T-cell panel, TCR gene rearrangement studies, and serum tryptase. The most frequent causes of HE include infections, especially those related to tissue-invasive helminths, allergic/vasculitic diseases, drugs, and meta­ static cancer. Primary HE is the focus of this chapter and is considered when a cause for secondary eosinophilia is not readily apparent. In the presence of normal BM morphology and absence of genetic abnormalities, the two major diagnostic possibilities are lymphocytic variant HE and idiopathic HE (Table 115-3); the former is character­ ized by the presence of an abnormal T-cell phenotype or clone. Both conditions might be associated with tissue/organ dysfunction due to eosinophilic infiltrates, in which case their nomenclature is modified into lymphocytic variant hypereosinophilic syndrome and idiopathic hypereosinophilic syndrome (iHES), respectively. In the presence of a TKGF, a diagnosis of myeloid/lymphoid neoplasm with eosinophilia and TKGF is considered (Table 115-3). The genes involved in TKGFassociated HE are listed in Table 115-6: PDGFRA, PDGFRB, FGFR1, ABL, JAK2, and FLT3. Once the latter possibility is excluded, other ICC-defined myeloid or lymphoid neoplasms (e.g., systemic mastocy­ tosis, acute myeloid or lymphoblastic leukemia, CML, MPN or MDS/ MPN, Hodgkin’s and non-Hodgkin’s lymphoma) must be considered and excluded. CEL-NOS is considered in the presence of cytogenetic abnormalities, excess blasts, or morphologic evidence of dysplasia, including that of megakaryocytes. The diagnostic workup for HE that is not associated with morpho­ logically overt myeloid malignancy should start with PB mutation screening for PDGFRA and PDGFRB mutations using fluorescence in situ hybridization (FISH) or reverse transcriptase polymerase chain reaction. If mutation screening is negative, a BM examination with cytogenetic and molecular studies is indicated. In this regard, one must first pay attention to the presence or absence of TKGF or associ­ ated cytogenetic abnormalities (Table 115-6). CEL-NOS is a subset of clonal eosinophilia that is neither molecularly defined nor classified as an alternative clinicopathologically assigned myeloid malignancy. We prefer to use the term strictly in patients with an HES phenotype who also display either a clonal cytogenetic/molecular abnormality, excess blasts in the BM or PB, or abnormal BM morphology (Table 115-6). CHAPTER 115 Less Common Lymphoid and Myeloid Malignancies ■ ■HYPEREOSINOPHILIA ASSOCIATED WITH TYROSINE KINASE GENE FUSIONS Both platelet-derived growth factor receptors α (PDGFRA; located on chromosome 4q12) and β (PDGFRB; located on chromosome 5q31q32) are involved in MPN-relevant activating mutations. Clinical phe­ notype in both instances includes prominent blood eosinophilia and excellent response to imatinib therapy. In regard to PDGFRA muta­ tions, the most popular is FIP1L1-PDGFRA, a karyotypically occult del(4)(q12), which was described in 2003 as an imatinib-sensitive acti­ vating mutation. Functional studies have demonstrated transforming properties in cell lines and the induction of MPN in mice. Cloning of the FIP1L1-PDGFRA fusion gene identified a novel molecular mecha­ nism for generating this constitutively active fusion tyrosine kinase, wherein an ~800 kb interstitial deletion within 4q12 fuses the 5′ por­ tion of FIP1L1 to the 3′ portion of PDGFRA. FIP1L1-PDGFRA occurs in a very small subset of patients who present with the phenotypic features of either systemic mastocytosis (SM) or HES, but the presence of the mutation reliably predicts complete hematologic and molecular response to imatinib therapy. In a retrospective survey of 151 patients with FIP1L1-PDGFRA– associated eosinophilia (143 males; mean age at diagnosis, 49 years), organopathy involved the spleen (44%), skin (32%), lungs (30%), heart (19%), and CNS (9%); none of 31 patients initially treated with corticosteroids achieved complete hematologic remission, whereas all 148 patients treated with imatinib achieved complete hematologic responses and also molecular responses, when evaluated. Treatment discontinuation was documented in 46 patients followed by a 57% relapse rate; the 1-, 5-, and 10-year overall survival rates in imatinibtreated patients were 99%, 95%, and 84%, respectively. Other studies have confirmed the possibility of treatment-free remissions in some patients after imatinib discontinuation. Infrequent occurrence of FIP1L1-PDGFRA–mutated AML associated with eosinophilia has also been shown to respond to low-dose imatinib therapy (100 mg/d). The association between eosinophilic myeloid malignancies and PDGFRB rearrangement was first characterized and published in 1994 when fusion of the tyrosine kinase encoding region of PDGFRB to the ets-like gene, ETV6 (ETV6-PDGFRB, t(5;12)(q33;p13), was demonstrated. The fusion protein was transforming to cell lines and resulted in constitutive activation of PDGFRB signaling. Since then, several other PDGFRB fusion transcripts with similar disease pheno­ types have been described, cell line transformation and MPD induction in mice have been demonstrated, and imatinib therapy was effective when employed. The 8p11 myeloproliferative syndrome (EMS) (also known as human stem cell leukemic/lymphoma syndrome) constitutes a clini­ cal phenotype with features of both lymphoma and eosinophilic MPN and is characterized by a fusion mutation that involves the gene for fibroblast growth factor receptor 1 (FGFR1), which is located on chro­ mosome 8p11 [e.g., ZMYM2::FGFR1, t(8;13)(p11.1;q12.1)]; disease phenotypes include T-cell acute lymphoblastic leukemia, large B-cell lymphoma, and MPN-like disease with HE. In EMS, both myeloid and lymphoid lineage cells exhibit the 8p11 translocation, thus demon­ strating the stem cell origin of the disease. The disease features several 8p11-linked chromosome translocations, and some of the correspond­ ing fusion FGFR1 mutants have been shown to transform cell lines and induce EMS- or CML-like disease in mice depending on the specific FGFR1 partner gene (ZNF198 or BCR, respectively). Consistent with this laboratory observation, some patients with BCR-FGFR1 mutation manifest a more indolent CML-like disease. The mechanism of FGFR1 activation in EMS is similar to that seen with PDGFRB-associated MPN; the tyrosine kinase domain of FGFR1 is juxtaposed to a dimer­ ization domain from the partner gene. EMS is an aggressive disease often requiring combination chemotherapy followed by ASCT. Pemi­ gatinib, which targets FGFR1/2/3, has been introduced and shown to induce hematologic and cytogenetic response in >70% of patients with FGFR1-rearranged myeloid/lymphoid neoplasms. PART 4 Oncology and Hematology The 2022 ICC includes a number of other subcategories of myeloid/ lymphoid neoplasms with eosinophilia and TKGFs (M/LN-eo-TK): (1) ETV6::ABL1, t(9;12)(q34.1;p13.2), phenotypically similar to CML and treated the same way with imatinib or similar tyrosine kinase inhibitors (TKIs) with good response; (2) PCM1::JAK2 or BCR::JAK2 or other JAK2 partners, t(8;9)(p22;p24.1), phenotypically similar to MPN or MDS/MPN with >90% response rate to ruxolitinib but not durable and requiring bridging to ASCT; and (3) ETV6::FLT3, t(12;13) (p13.2;q12.2), phenotypically similar to lymphoblastic leukemia or lymphoma, CEL, or MDS/MPN, with some responses seen with FLT3 inhibitor therapy. ■ ■HYPEREOSINOPHILIC SYNDROME Blood eosinophilia that is neither secondary nor clonal is operationally labeled as being “idiopathic.” HES is a subcategory of idiopathic eosin­ ophilia with persistent increase of the AEC to ≥1.5 × 109/L and pres­ ence of eosinophil-mediated organ damage, including cardiomyopathy, gastroenteritis, cutaneous lesions, sinusitis, pneumonitis, neuritis, and vasculitis. In addition, some patients manifest thromboembolic com­ plications, hepatosplenomegaly, and either cytopenia or cytosis. BM histologic and cytogenetic/molecular studies should be exam­ ined before a working diagnosis of HES is made. Additional blood studies that are currently recommended during the evaluation of HES include serum tryptase (an increased level suggests mastocytosis and warrants molecular studies to detect FIP1L1-PDGFRA), T-cell immunophenotyping, and T-cell receptor antigen gene rearrangement analysis (a positive test suggests an underlying clonal or phenotypically abnormal T-cell disorder). In addition, initial evaluation in HES should include echocardiogram and measurement of serum troponin levels to screen for myocardial involvement by the disease. Initial evaluation of the patient with eosinophilia should include tests that facilitate assessment of target organ damage, including com­ plete blood count, chest x-ray, echocardiogram, and serum troponin level. Increased level of serum cardiac troponin has been shown to correlate with the presence of cardiomyopathy in HES. Typical echo­ cardiographic findings in HES include ventricular apical thrombus, posterior mitral leaflet or tricuspid valve abnormality, endocardial thickening, dilated left ventricle, and pericardial effusion. In a Mayo Clinic study of 98 consecutive patients with idiopathic eosinophilia, including HES, median age was 53 years (55% male), and overt organ involvement was seen in >80% of the cases, including 54% involving organs other than the skin. The frequencies of cardiac involvement, hepatosplenomegaly, and increased serum tryptase and interleukin (IL) 5 levels were 8%, 4%, 24%, and 31%, respectively. The study also revealed that 11% of the affected patients harbored pathoge­ netic mutations including TET2, ASXL1, and KIT; the presence of such mutations did not appear to influence phenotype, and the number of informative cases was too small to assess prognostic relevance. Instead, the study identified anemia and presence of cardiac involvement or hepatosplenomegaly as risk factors for survival. Glucocorticoids are the cornerstone of therapy in HES. Treatment with oral prednisone is usually started at 1 mg/kg per day and contin­ ued for 1–2 weeks before the dose is tapered slowly over the ensuing 2–3 months. If symptoms recur at a prednisone dose level of >10 mg/d, either hydroxyurea or interferon α is used as steroid-sparing agent. In patients in whom usual therapy fails as outlined above, mepolizumab or alemtuzumab might be considered. Mepolizumab is a monoclonal antibody that targets IL-5, which is a well-recognized growth factor for eosinophils. Alemtuzumab targets the CD52 antigen, which has been shown to be expressed by eosinophils but not by neutrophils. In a recently reported placebo-controlled phase 3 study, HES patients received subcutaneous mepolizumab (300 mg) every 4 weeks, in addi­ tion to their preprotocol therapy, and experienced significantly fewer disease flare-ups or treatment discontinuations (28 vs 56% for pla­ cebo), without excess adverse events. Mepolizumab was U.S. Food and Drug Administration approved for use in HES on September 25, 2020. In a smaller phase 2 study, benralizumab (monoclonal antibody target­ ing the receptor for IL-5; 30 mg given subcutaneously every 4 weeks) was also shown to reduce eosinophil count more efficiently compared to placebo (90 vs 30%). ■ ■MASTOCYTOSIS SM is characterized by proliferation of neoplastic mast cells (MCs) in BM and/or other extracutaneous organs and is distinguished from cutaneous mastocytosis (CM; skin involvement only) and mast cell sarcoma (MCS; high-grade focal MC tumor). According to the ICC and WHO-proposed fifth edition (WHO5) classification systems (Table 115-4), SM is subclassified into indolent (ISM), smoldering (SSM), aggressive (ASM), SM with associated myeloid (SM-AMN, per ICC) or hematologic (SM-AHN, per WHO5) neoplasm, and mast cell leukemia (MCL). WHO5 also includes an additional “low-grade” SM subtype, namely BM mastocytosis (BMM); the latter is described as consisting of (1) absence of skin lesions, (2) absence of B findings, and (3) serum tryptase level <125 ng/mL. The ICC considers BMM as a clinicopathologic variant and not an SM subtype. Both ICC and WHO5 have also refined their diagnostic criteria for SM in general. Diagnosis per ICC requires the presence of a major criterion (multifo­ cal aggregates of ≥15 MCs) or, in its absence, the presence of at least three minor criteria, including (1) BM biopsy or extracutaneous organ section with >25% MCs with atypical morphology; (2) MC expres­ sion of CD25, CD2, and/or CD30; (3) KIT D816V or other activating KIT mutation; and (4) increased serum tryptase >20 ng/mL (needs to be adjusted in the presence of hereditary α-tryptasemia); in addi­ tion, presence of myeloid/lymphoid neoplasm with eosinophilia with TKGRs must be excluded. SM diagnosis per WHO5 requires the pres­ ence of the major criterion as well as one other minor criterion or at least three minor criteria. The term advanced SM (AdvSM) includes ASM, SM-AMN/AHN, and MCL; AdvSM is distinguished from non-AdvSM by the presence of either an associated myeloid/hematologic neoplasm (e.g., AML, CMML, MDS, MPN) or organopathy resulting from MC infiltra­ tion. MC-associated organopathy is defined by the presence of one or more C findings: (1) ≥1 cytopenia (hemoglobin <10 g/dL, absolute neutrophil count <1 × 109/L, or platelet count <100 × 109/L); (2) pal­ pable hepatomegaly with abnormal liver function tests, ascites, or por­ tal hypertension; (3) palpable splenomegaly with thrombocytopenia attributed to hypersplenism; (4) MC infiltration of the gastrointestinal system with resultant malabsorption with weight loss; and (5) large osteolytic lesions with or without pathologic fractures. The ICC system requires the AHN component in SM-AHN to be of myeloid lineage, resulting in a revised nomenclature (i.e., SM-AMN). By contrast, WHO5-defined SM-AHN allows the AHN component to be of either myeloid or lymphoid lineage. Additional divergence between ICC and WHO5 concerns the definition of MCL; both systems require the presence of ≥20% MCs in BM aspirate, but ICC criteria require, in addition, immature cytomorphology (i.e., promastocytes, metachro­ matic blast-like cells, or multinucleated or highly pleomorphic MC) of the excess MCs; furthermore, ICC no longer differentiates between leukemic (≥10% circulating MC) versus aleukemic MCL variants. Both the ICC and WHO5 use similar B findings to distinguish indolent from smoldering SM, with the latter requiring the presence of two or more B findings, including (1) MCs >30% of BM cellularity on BM biopsy and serum tryptase >200 ng/mL; (2) cytopenia not meeting criteria for C findings or cytosis; and (3) palpable hepatomegaly without liver func­ tion impairment or splenomegaly without thrombocytopenia or >1 cm lymphadenopathy on palpation or imaging; in addition, KIT D816V VAF ≥10% qualifies as a B finding, per WHO5. In a study of 329 patients with AdvSM, including WHO5 subcat­ egories of SM-AHN (64%), ASM (30%), and MCL (6%) or ICC subcat­ egories of SM-AMN (64%), ASM (33%), and MCL (3%), multivariable analysis that included the Mayo Alliance risk factors for survival in SM (age >60 years, anemia, thrombocytopenia, increased alkaline phosphatase) revealed more accurate survival prediction with the ICC versus WHO5 classification order: (1) survival was significantly worse with ICC-defined MCL versus WHO5-defined MCL with otherwise mature MC cytomorphology; (2) prognostic distinction was con­ firmed for ICC-defined MCL versus ICC-defined SM-AMN but not for WHO5-defined MCL versus WHO-defined SM-AHN; (3) survival was similar between WHO5-defined MCL with mature cytomorphol­ ogy versus ICC-defined SM-AMN; and (4) ICC-defined SM-AMN but not WHO-defined SM-AHN with lymphoid lineage was prognostically distinct from ASM. Accordingly, our views on the classification of AdvSM are in line with those of the ICC system. We believe that these details are therapeutically relevant considering the emergent nature of ICC-defined MCL and the fact that SM-AMN, as opposed to SMAHN, carries a prognostically worse designation that might require therapeutic intervention with ASCT sooner than later. Currently available drugs for treatment include KIT inhibitors (KITi), which exhibit remarkable activity in reducing MC and mutant KIT burden but have not been shown to extend survival. On the other hand, we are impressed by the remarkable activity of currently available KITi on the MC component of SM, with the caveat that such drugs are expensive, have significant side effects, and need long-term use. The first step in treatment decision-making is to identify whether the AMN component takes priority over the SM component of the disease, for treatment purposes. High-grade AMNs, including AML, high-/veryhigh-risk MDS or CMML, or those with >10% BM blasts, likely take precedence in this regard. Accordingly, in a fit patient with SM-AML or SM-high/very-high-risk MDS, intensive remission induction therapy or hypomethylating agent (HMA) therapy can be considered. If the SM is incidentally diagnosed or is associated with minimal symptoms, we generally limit SM therapy to supportive/symptomatic care, includ­ ing with antihistamine and/or antileukotriene agents or cromolyn, as well as taking precautions for anaphylaxis prevention/treatment. For SM with significantly high MC or symptom burden, concurrent MC cytoreduction can be considered, particularly for those with relapsed/ refractory disease, although there are no clear protocols in this regard. ASCT has an important role in the treatment of SM-high-grade AMN, although there is no consensus regarding optimal timing, deb­ ulking strategy, and so on; overall survival appears to be most favorable for SM-AMN patients compared to other subgroups, and survival was superior in those receiving myeloablative versus reduced-intensity conditioning, thereby indicating the need for effective cytoreduction prior to stem cell transplantation. For SM-AMN patients with a lowgrade AMN, such as PV or ET, or low-risk MDS, conventional therapy for the AMN including therapeutic phlebotomies, low-dose aspirin, hydroxyurea or interferon α, or erythropoiesis-stimulating agents is pursued. If the SM disease component does not warrant cytoreduction (e.g., no C findings), supportive/symptomatic care, as described earlier, is pursued, along with intermittent monitoring of disease status. If MC cytoreduction is warranted, monotherapy with a TKI or cladribine can be pursued, depending on individual risk, benefit considerations, treat­ ment availability, cost considerations, and so on. We find cladribine, midostaurin, and avapritinib to be reasonable drug considerations for AdvSM as well as MCL. While avapritinib has theoretical advantages over midostaurin, including a more potent inhibitory effect on KIT D816V and proven efficacy in patients previ­ ously treated with midostaurin, we are agnostic regarding the choice of TKI given the lack of head-to-head comparison; instead, we recom­ mend an individualized approach to TKI selection that weighs drug accessibility/affordability, comorbid conditions, risk tolerance for anticipated adverse events, and provider/center experience with the particular TKI. We continue to utilize cladribine as a reasonable alter­ native to TKI therapy, based on decades-long experience, long-term safety record, and qualitatively better toxicity profile that is mostly limited to cytopenias, as opposed to cognitive impairment and other side effects with avapritinib and intolerance due to diarrhea with midostaurin. For ASM patients who exhibit disease progression and/ or leukemic transformation despite adequate TKI dosing or cladribine, we recommend ASCT as salvage therapy. We consider “true” MCL an oncologic emergency, and collaboration with an experienced hema­ topathologist to expeditiously confirm the diagnosis is critical, as is expedited molecular testing for KIT D816V and other AMN-relevant mutations. CHAPTER 115 ■ ■DENDRITIC AND HISTIOCYTIC NEOPLASMS Dendritic cell (DC) and histiocyte/macrophage neoplasms are extremely rare. DCs are antigen-presenting cells, whereas histiocyte/ macrophages are antigen-processing cells. BM myeloid stem cells (CD34+) give rise to monocyte (CD14+, CD68+, CD11c+, CD1a–) and DC (CD14–, CD11c+/–, CD1a+/c) precursors. Monocyte precursors, in turn, give rise to macrophages (CD14+, CD68+, CD11c+, CD163+, lysozyme+) and interstitial DCs (CD68+, CD1a–). DC precursors give rise to Langerhans cell DCs (Birbeck granules, CD1a+, S100+, langerin+) and plasmacytoid DCs (CD68+, CD123+). Follicular DCs (CD21+, CD23+, CD35+) originate from mesenchymal stem cells. Dendritic and histiocytic neoplasms are operationally classified into macrophage/histiocyte-related and DC-related. The former includes histiocytic sarcoma/malignant histiocytosis and the latter Langerhans cell histiocytosis, Langerhans cell sarcoma, interdigitating DC sarcoma, and follicular DC sarcoma. Less Common Lymphoid and Myeloid Malignancies Histiocytic Sarcoma/Malignant Histiocytosis  Histiocytic sarcoma represents malignant proliferation of mature tissue histiocytes and is often localized. Median age at diagnosis is estimated at 46 years with slight male predilection. Some patients might have a history of lymphoma, MDS, or germ cell tumors at time of disease presentation. The three typical disease sites are lymph nodes, skin, and the gastro­ intestinal system. Patients may or may not have systemic symptoms including fever and weight loss, and other symptoms include hepato­ splenomegaly, lytic bone lesions, and pancytopenia. Immunopheno­ type includes presence of histiocytic markers (CD68, lysozyme, CD11c, CD14) and absence of myeloid or lymphoid markers. Prognosis is poor, and treatment is often ineffective. The term malignant histiocytosis refers to a disseminated disease and systemic symptoms. Lymphomalike treatment induces complete remissions in some patients, and median survival is estimated at 2 years. In one of the largest series of histiocytic sarcoma, 330 cases were included with median age of 61 years (59% male). In the latter study, the most common sites of pre­ sentation were skin, connective tissue, lymph nodes, gastrointestinal tract, and hematopoietic system; median overall survival was 6 months, and treatment included systemic chemotherapy, radiotherapy, and surgery. Factors associated with poor outcome included older age, high comorbidity index, and disease involving the hematopoietic and reticuloendothelial system. Langerhans Cell Histiocytosis  Langerhans cells (LCs) are spe­ cialized DCs that reside in mucocutaneous tissue and upon activation become specialized for antigen presentation to T cells. LC histiocytosis (LCH; also known as histiocytosis X) represents neoplastic proliferation of LCs (S100+, CD1a+, and Birbeck granules on electron microscopy). LCH incidence is estimated at 5 per million, and the disease typically affects children, with a male predilection. Presentation can be either unifocal (eosinophilic granuloma) or multifocal. The former usually affects bones and less frequently lymph nodes, skin, and lung, while the latter is more disseminated. Unifocal disease often affects older chil­ dren and adults, while multisystem disease affects infants. LCH of the lung in adults is characterized by bilateral nodules. Prognosis depends on organs involved. Only 10% of patients progress from unifocal to multiorgan disease. LCH of the lung might improve upon cessation of smoking. Approximately 55% of patients with LCH harbor BRAF V600E gain-of-function mutations, which indicates high-risk disease and resistance to first-line therapy, while responses to targeted therapy with vemurafenib have been reported. Other forms of treatment for LCH include combination chemotherapy and MEK inhibitors in BRAF wild-type but with other MAPK pathway mutations. Unfortunately, such targeted therapy has not secured long-lasting treatment-free remissions. In one retrospective study, 33 adult patients with LCH were studied including 21 with single-system LCH, 10 with multisystem LCH, and 2 with pulmonary LCH. Patients with single-system unifocal involve­ ment were successfully treated with local therapies such as surgery and radiotherapy. Most of the multisystem LCH patients and patients with single-system multifocal involvement were treated with systemic chemotherapy. Cladribine was the first choice in 10 of 11 patients who received chemotherapy. Among all patients, the overall response rate (ORR) was 97%. Among those who had cladribine in the first line, the ORR was 81%. All these patients achieved a complete remission and were alive at the last visit. The median follow-up was 38 months (range, 2–183 months). The median progression-free survival (PFS) has not yet been reached. Ten-year PFS was 90.9%. Expert consensus recommenda­ tions for treatment include local therapies for unifocal disease, smoking cessation as first-line therapy for pulmonary LCH, and systemic therapy for multifocal and multisystem disease; the latter might include cladrib­ ine, cytarabine, and targeted therapy with BRAF and MEK inhibitors. PART 4 Oncology and Hematology In one study, 26 adult patients with non-LCH, including 17 with Erdheim-Chester disease (ECD), 3 with Rosai-Dorfman disease (RDD), 5 with ECD/RDD, and 1 with ECD/LCH, were treated with the MEK inhibitor trametinib; the most common treatment-related toxicity was rash (27%), whereas the response rate of the 17 evaluable patients was 71%, including 73% without a detectable BRAF V600E; median time-to-treatment failure was 37 months; most patients har­ bored mutations in BRAF (either classic BRAF V600E or other BRAF alterations) or alterations in other genes involved in the MAPK path­ way (e.g., MAP2K, NF1, GNAS, or RAS). Langerhans Cell Sarcoma  Langerhans cell sarcoma (LCS) also represents neoplastic proliferation of LCs with overtly malignant mor­ phology. The disease can present de novo or progress from antecedent LCH. There is a female predilection, and median age at diagnosis is estimated at 41 years. Immunophenotype is similar to that seen in LCH, and liver, spleen, lung, and bone are the usual sites of disease. Prognosis is poor, and treatment is generally ineffective. Interdigitating Dendritic Cell Sarcoma  Interdigitating DC sarcoma (IDCS), also known as reticulum cell sarcoma, represents neoplastic proliferation of interdigitating DCs. The disease is extremely rare and affects elderly adults with no sex predilection. Typical presen­ tation is asymptomatic solitary lymphadenopathy. Immunophenotype includes S100+ and negative for vimentin and CD1a. Prognosis ranges from benign local disease to widespread lethal disease. Follicular Dendritic Cell Sarcoma  Follicular dendritic cells (FDCs) reside in B-cell follicles and present antigen to B cells. FDC neoplasms (FDCNs) are usually localized and often affect adults. FDCN might be associated with Castleman’s disease in 10–20% of cases, and increased incidence in schizophrenia has been reported. Cervical lymph nodes are the most frequent site of involvement in FDCNs, and other sites include maxillary, mediastinal, and retroperitoneal lymph nodes; oral cavity; the gastrointestinal system; skin; and breast. Sites of metastasis include lung and liver. Immunophenotype includes CD21, CD35, and CD23. Clinical course is typically indolent, and treatment includes surgical excision followed by regional radiotherapy and some­ times systemic chemotherapy. Hemophagocytic Lymphohistiocytosis (see Chap. 68)  Hemo­ phagocytic lymphohistiocytosis (HLH) represents nonneoplastic pro­ liferation and activation of macrophages and cytotoxic lymphocytes that induce cytokine-mediated bone marrow suppression, features of intense phagocytosis in bone marrow and liver, and multiorgan dysfunction including cytopenias, coagulopathy, and fever. HLH may result from genetic (primary) or acquired (secondary) disorders of macrophages. The former entail genetically determined inability to regulate macrophage proliferation and activation and might include alterations in familial HLH genes, including those of perforin (PRF1, UNC13D, STXBP2, and STX11), granule/pigment abnormality genes (RAB27A, LYST, and AP3B1), or X-linked lymphoproliferative disease genes (SH2D1A and XIAP). Acquired HLH is often precipitated by viral infections, including Epstein-Barr virus. HLH might also accom­ pany certain malignancies such as T-cell lymphoma and autoimmune diseases, ASCT, and chimeric antigen receptor (CAR) T-cell therapy. In a recent population-based study from Sweden, the annual incidence of malignancy-associated HLH had increased 10-fold and was at least 0.71 per 100,000 adults from 2012 to 2018, and early survival improved significantly, likely due to increased awareness and more HLH-directed therapy. Regardless of the cause, the common tissue/organ-damaging pathway involves excessive inflammatory cytokine release, including IL-6, IL-2, IL-1, interferon γ, and tumor necrosis factor (TNF). Clinical presentation of HLH includes fever, severe constitutional symptoms, enlarged lymph nodes, hepatosplenomegaly, neurologic dysfunction, and abnormalities in multiple organ function tests. Diagnosis is accomplished by either detection of HLH-related muta­ tions or meeting five of the following eight conventional criteria: (1) hemophagocytosis in the bone marrow/spleen/lymph nodes; (2) serum ferritin ≥500 µg/L; (3) hypofibrinogenemia (fibrinogen ≤1.5 g/L) or hypertriglyceridemia (triglycerides ≥3 mmol/L); (4) low NK cell activ­ ity; (5) elevated soluble IL-2 receptor (CD25) ≥2400 U/mL; (6) bi- or tri-cytopenia (platelets <100 × 109/L, hemoglobin <9 g/dL, absolute neutrophil count <1 × 109/L); (7) splenomegaly palpable >3 cm below left costal margin; and (8) fever. Clinical course is often fulminant and fatal with reported 1-year survival rates of <30% in patients with hematologic malignancy. Current therapeutic approaches for primary or secondary HLH include the so-called HLH-94 protocol, which con­ sists of weekly treatments with etoposide and dexamethasone, stem cell transplant, emapalumab (a monoclonal antibody that binds and neu­ tralizes interferon γ and is approved in primary HLH), and the JAK1/2 inhibitor ruxolitinib. The latter has recently been shown to increase survival rate in affected patients to >80%. ■ ■FURTHER READING Alaggio R et al: The 5th edition of the World Health Organization Classification of Haematolymphoid Tumours: Lymphoid neoplasms. Leukemia 36:1720, 2022. Arber DA et al: International Consensus Classification of myeloid neoplasms and acute leukemias: Integrating morphologic, clinical, and genomic data. Blood 140:1200, 2022. de Leval L et al: A practical approach to the modern diagnosis and classification of T- and NK-cell lymphomas. Blood 144:1855, 2024. Khoury JD et al: The 5th edition of the World Health Organization Classification of Haematolymphoid Tumours: Myeloid and histio­ cytic/dendritic neoplasms. Leukemia 36:1703, 2022. Miranda RN et al: The 5th edition of the World Health Organization Classification of Hematopoietic and lymphoid tissues: Mature T-cell, NK-cell, and stroma-derived neoplasms of lymphoid tissues. Mod Pathol 37:100512, 2024. Szuber N et al: Chronic neutrophilic leukemia: 2022 update on diagno­ sis, genomic landscape, prognosis, and management. Am J Hematol 97:491, 2022. # 46 - 116 Plasma Cell Disorders ### 116 Plasma Cell Disorders Nikhil C. Munshi, Dan L. Longo, Kenneth C. Anderson Plasma Cell Disorders The plasma cell disorders are monoclonal neoplasms related to each other by virtue of their development from common progenitors in the late B-lymphocyte lineage. Multiple myeloma (MM), Waldenström’s macroglobulinemia, primary amyloidosis (Chap. 117), and the heavy chain diseases comprise this group and may be designated by a variety of synonyms such as monoclonal gammopathies, paraproteinemias, plasma cell dyscrasias, and dysproteinemias. Mature B lymphocytes des­ tined to produce IgG bear surface immunoglobulin molecules of both μ and γ heavy chain isotypes with both isotypes having identical idio­ types (variable regions). Under normal circumstances, maturation to antibody-secreting plasma cells and their proliferation is stimulated by exposure to the antigen for which the surface immunoglobulin is spe­ cific; however, in the plasma cell disorders, the control over this process is lost. The clinical manifestations of all the plasma cell disorders relate to the expansion of the neoplastic cells, to the secretion of cell products (immunoglobulin molecules or subunits, lymphokines), and to some extent to the host’s response to the tumor. Normal development of B lymphocytes is discussed in Chap. 360 and depicted in Fig. 113-2. Three categories of structural variation are present among immu­ noglobulin molecules that form antigenic determinants, and these are used to classify immunoglobulins. Isotypes are those determinants that distinguish among the main classes of antibodies of a given species and are the same in all normal individuals of that species. Therefore, isotypic determinants are, by definition, recognized by antibodies from a distinct species (heterologous sera) but not by antibodies from the same species (homologous sera). There are five heavy chain isotypes (M, G, A, D, E) and two light chain isotypes (κ, λ). Allotypes are distinct determinants that reflect regular small differences between individuals of the same species in the amino acid sequences of otherwise similar immunoglobulins. These differences are determined by allelic genes; by definition, they are detected by antibodies made in the same spe­ cies. Idiotypes are the third category of antigenic determinants. They are unique to the molecules produced by a given clone of antibodyproducing cells. Idiotypes are formed by the unique structure of the antigen-binding portion of the molecule. Antibody molecules (Fig. 116-1) are composed of two heavy chains (~50,000 molecular weight [mol wt]) and two light chains (~25,000 mol wt). Each chain has a constant portion (limited amino acid sequence variability) and a variable region (extensive sequence variability). The light and heavy chains are linked by disulfide bonds and are aligned so that their variable regions are adjacent to one another. This variable region forms the antigen recognition site of the antibody molecule; its unique structural features form idiotypes that are reliable markers for a particular clone of cells because each antibody is formed and secreted by a single clone. Because of the mechanics of the gene rearrangements necessary to specify the immunoglobulin variable regions (VDJ joining for the heavy chain, VJ joining for the light chain), a particular clone rearranges only one of the two chromosomes to produce an immuno­ globulin molecule of only one light chain isotype and only one allotype (allelic exclusion) (Fig. 116-1). After exposure to antigen, the variable region may become associated with a new heavy chain isotype (class switch). Each clone of cells performs these sequential gene arrange­ ments in a unique way. This results in each clone producing a unique immunoglobulin molecule. In most plasma cells, light chains are syn­ thesized in slight excess, secreted as free light chains, and cleared by the kidney, but <10 mg of such light chains are excreted per day. Electrophoretic analysis permits separation of components of the serum proteins (Fig. 116-2). The immunoglobulins move hetero­ geneously in an electric field and form a broad peak in the gamma region. There is a sharp spike in this region called an M component (M for monoclonal) in the sera of patients with plasma cell tumors. Less commonly, the M component may appear in the β2 or α2 globulin region. The monoclonal antibody must be present at a concentration of at least 5 g/L (0.5 g/dL) to be accurately quantitated by this method. This corresponds to ~109 antibody producing cells. Confirmation of the type of immunoglobulin and that it is truly monoclonal is deter­ mined by immunoelectrophoresis that reveals a single heavy and/or light chain type. Hence, immunoelectrophoresis and electrophoresis provide qualitative and quantitative assessment of the M component, respectively. The amount of M component in the serum is a reli­ able measure of the tumor burden and an excellent tumor marker to manage therapy, yet it is not specific enough to be used to screen asymptomatic patients. In addition to the plasma cell disorders, M components may be detected in other lymphoid neoplasms such as chronic lymphocytic leukemia (CLL) and lymphomas of B- or T-cell origin; nonlymphoid neoplasms such as chronic myeloid leukemia, breast cancer, and colon cancer; a variety of nonneoplastic conditions such as cirrhosis, sarcoidosis, parasitic diseases, Gaucher’s disease, and pyoderma gangrenosum; and a number of autoimmune conditions, including rheumatoid arthritis, myasthenia gravis, and cold agglutinin disease. Monoclonal proteins are also observed in immunosuppressed patients after organ transplant and, rarely, allogeneic transplant. At least two very rare skin diseases—lichen myxedematosus (also known as papular mucinosis) and necrobiotic xanthogranuloma—are associ­ ated with a monoclonal gammopathy. In papular mucinosis, highly cationic IgG is deposited in the dermis of patients. This organ specific­ ity may reflect the specificity of the antibody for some antigenic com­ ponent of the dermis. Necrobiotic xanthogranuloma is a histiocytic infiltration of the skin, usually of the face, that produces red or yellow nodules that can enlarge to plaques. Approximately 10% progress to myeloma. Five percent of patients with sensory motor neuropathy also have a monoclonal paraprotein. CHAPTER 116 Plasma Cell Disorders The nature of the M component is variable in plasma cell disorders. It may be an intact antibody molecule of any heavy chain subclass, or it may be an altered antibody or fragment. Isolated light or heavy chains may be produced. In some plasma cell tumors such as extramedullary or solitary bone plasmacytomas, less than one-third of patients will have an M component. In ~20% of myelomas, only light chains are produced and, in most cases, are secreted in the urine as Bence Jones proteins. The frequency of myelomas of a particular heavy chain class is roughly proportional to the serum concentration, and therefore, IgG myelomas are more common than IgA and IgD myelomas. In ~1% of patients with myeloma, biclonal or triclonal gammopathy is observed. MULTIPLE MYELOMA ■ ■DEFINITION MM represents a malignant proliferation of plasma cells derived from a single clone. The tumor, its products, and the host response to it result in a number of organ dysfunctions and symptoms, including bone pain or fracture, renal failure, susceptibility to infection, anemia, hypercal­ cemia, and occasionally clotting abnormalities, neurologic symptoms, and manifestations of hyperviscosity. ■ ■ETIOLOGY The cause of myeloma is not known. Myeloma occurred with increased frequency in those exposed to the radiation of nuclear warheads in World War II after a 20-year latency. Myeloma has been seen more commonly than expected among farmers, wood workers, leather work­ ers, and those exposed to petroleum products. A variety of recurrent chromosomal alterations have been found in patients with myeloma: hyperdiploidy (trisomies involving one or more of chromosomes 3, 5, 7, 9, 11, 15, 19, or 21) is observed in half of the patients, while the other half have translocations involving the 14q32 chromosome with variable partners including t(11;14)(q13;q32), t(4;14)(p16;q32), and t(14;16). Other frequent abnormalities include 13q14 deletion, 1q amplification or 1p deletion, and 17p13 deletions. Evidence is strong that errors in switch recombination—the genetic mechanism to change antibody heavy chain isotype—participate in the early transformation process. However, no single common molecular pathogenetic pathway has yet λ Light-chain locus L1 Vλ1 L2 Vλ2 Jλ1 Jλ2 Jλ4 L Vλ–30 Cλ1 Cλ2 Cλ4 κ Light-chain locus L1 Vκ1 L2 Vκ2 L3 Vκ3 Jκ1–5 L Vκ–36 Cκ Heavy-chain locus L1 VH1 L2 VH2 L3 VH3 JH 1–6 Cµ LH VH–40 DH1–23 Light chain Heavy chain L V J C L V J D Germline DNA PART 4 Oncology and Hematology Somatic recombination DNA RNA Protein D–J rearranged DNA joined Somatic recombination L V J C V–J or V–DJ joined rearranged DNA Transcription L V J C Primary transcript RNA AAA Splicing L V J C mRNA AAA Translation VL CL Polypeptide chain FIGURE 116-1  Immunoglobulin genetics and the relationship of gene segments to the antibody protein. The top portion of the figure is a schematic of the organization of the immunoglobulin genes, λ on chromosome 22, κ on chromosome 2, and the heavy chain locus on chromosome 14. The heavy chain locus is >2 megabases, and some of the D region gene segments are only a few bases long, so the figure depicts the schematic relationship among the segments, not their actual size. The bottom portion of the figure outlines the steps in going from the noncontiguous germline gene segments to an intact antibody molecule. Two recombination events juxtapose the V-D-J (or V-J for light chains) segments. The rearranged gene is transcribed, and RNA splicing cuts out intervening sequences to produce an mRNA, which is then translated into an antibody light or heavy chain. The sites on the antibody that bind to antigen (the so-called CDR3 regions) are encoded by D and J segments for heavy chains and the J segments for light chains. (Adapted from Janeway’s Immunobiology, 8th ed by Kenneth Murphy. Copyright © 2012 by Garland Science, Taylor & Francis Group, LLC. Used by permission of W. W. Norton & Company, Inc.) emerged. Genome sequencing efforts have allowed for characterization of critical genes, pathways, and clonal heterogeneity in myeloma. The median number of mutations per transcribed genome in myeloma is ~58, and within the whole genome, it is >7000. A very heterogeneous mutational landscape with no unifying mutation has been observed. The most frequently mutated genes are KRAS and NRAS (~20% each), followed by TP53, DIS3, FAM46C, and BRAF, all mutated in 5–10% C C L V DJ C L V DJ C L V DJ AAA C L V DJ AAA CH3 CH2 CH1 VH of patients. All other mutations were observed in <5% of the patients. These results are now being applied to develop new targeted personal­ ized therapies in myeloma. Evidence of complex clusters of subclonal variants is present at diagnosis, and additional mutations are acquired over time, indicative of genomic evolution that may drive disease progression. Interleukin (IL) 6 may play a role in driving myeloma cell proliferation. It remains difficult to distinguish benign from malignant SP G A M Κ λ SP G A M Κ λ SP G A M Κ λ Normal Polyclonal increase Monoclonal IgG lambda FIGURE 116-2  Representative patterns of serum electrophoresis and immunofixation. The upper panels represent agarose gel, middle panels are the densitometric tracing of the gel, and lower panels are immunofixation patterns. The panel on the left illustrates the normal pattern of serum protein on electrophoresis. Because there are many different immunoglobulins in the serum, their differing mobilities in an electric field produce a broad peak. In conditions associated with increases in polyclonal immunoglobulin, the broad peak is more prominent (middle panel). In monoclonal gammopathies, the predominance of a product of a single cell produces a “church spire” sharp peak, usually in the γ globulin region (right panel). The immunofixation (lower panel) identifies the type of immunoglobulin. For example, normal and polyclonal increases in immunoglobulins produce no distinct bands; however, the right panel shows distinct bands in IgG and lambda protein lanes, confirming the presence of IgG lambda monoclonal protein. (Courtesy of Dr. Neal I. Lindeman.) plasma cells based on morphologic criteria in all but a few cases (Fig. 116-3). ■ ■INCIDENCE AND PREVALENCE In 2024 in the United States, 35,780 new cases of myeloma were esti­ mated to be diagnosed, and 12,540 people were estimated to die from the disease. Myeloma increases in incidence with age. The median age at diagnosis is 69 years; it is uncommon under age 40. Males are more commonly affected than females, and blacks have nearly twice the incidence of whites. In 2021, myeloma accounted for 1.8% of all malignancies, with incidence rates per 100,000 of 8.1 and 5.1 in white and 17.1 and 13.0 in black men and women, respectively. ■ ■GLOBAL CONSIDERATIONS The incidence of myeloma is highest in blacks and Pacific Islanders; intermediate in Europeans and North American whites; and lowest in FIGURE 116-3  Multiple myeloma (marrow). The cells bear characteristic morphologic features of plasma cells: round or oval cells with an eccentric nucleus composed of coarsely clumped chromatin, a densely basophilic cytoplasm, and a perinuclear clear zone containing the Golgi apparatus. Binucleate and multinucleate malignant plasma cells can be seen. CHAPTER 116 Plasma Cell Disorders people from developing countries including Asia. The higher incidence in more developed countries may result from the combination of a lon­ ger life expectancy and more frequent medical surveillance. Incidence of MM in other ethnic groups including native Hawaiians, female Hispanics, American Indians from New Mexico, and Alaskan natives is higher relative to U.S. whites in the same geographic area. Chinese and Japanese populations have a lower incidence than whites. Immunopro­ liferative small-intestinal disease (IPSID) with α heavy chain disease is most prevalent in the Mediterranean area. Despite these differences in prevalence, the characteristics, response to therapy, and prognosis of myeloma are similar worldwide. ■ ■PATHOGENESIS AND CLINICAL MANIFESTATIONS MM cells bind via cell-surface adhesion molecules to bone marrow stromal cells (BMSCs) and extracellular matrix (ECM), which trig­ gers MM cell growth, survival, drug resistance, and migration in the bone marrow milieu (Fig. 116-4). These effects are due both to direct MM cell–BMSC binding via adhesion molecules and to induction of various cytokines, including IL-6, insulin-like growth factor type 1 (IGF-1), and vascular endothelial growth factor (VEGF). Growth, drug resistance, and migration are mediated via Ras/Raf/mitogen-activated protein kinase, PI3K/Akt, and protein kinase C signaling cascades, respectively. Other cellular elements in the bone marrow microen­ vironment also significantly impact MM cell growth and survival, especially interactions with endothelial cells and osteoclasts. Immune cells such as plasmacytoid dendritic cells (pDC), myeloid-derived sup­ pressor cells (MDSC), and T helper 17 (TH17) cells are increased in number and support myeloma growth, while antimyeloma immune responses, especially T helper and cytotoxic cells, B cells, and natural killer T cells, are suppressed. Bone pain is the most common symptom in myeloma, affecting nearly 70% of patients. The bone lesions of myeloma are caused by the proliferation of tumor cells, activation of osteoclasts that destroy bone, and suppression of osteoblasts that form new bone. The increased osteoclast activity is mediated by osteoclast activating factors (OAFs) produced by the myeloma cells (mediated by several cytokines, includ­ ing IL-1, lymphotoxin, VEGF, receptor activator of nuclear factor-κB [RANK] ligand, macrophage inhibitory factor [MIP]-1α, and tumor TH17 Osteoclast ↑Proliferation ↑Differentiation ↑Activity IL-17 RANK IL-6 MM cell RANKL IL-6 Cytokine-mediated signaling OPG Adhesion-mediated signaling ↑Differentiation ↑Activity Osteoblast DKK-1 PART 4 Oncology and Hematology Cytokines IL-6 VEGF IGF-1 SDF-1® Endothelial cells ↑Neoangiogenesis NF-κB BMSC FIGURE 116-4  Pathogenesis of multiple myeloma. Multiple myeloma (MM) cells interact with bone marrow stromal cells (BMSCs) and extracellular matrix proteins via adhesion molecules, triggering adhesion-mediated signaling as well as cytokine production. This triggers cytokine-mediated signaling that provides growth, survival, and antiapoptotic effects as well as development of drug resistance. Additional bidirectional interactions lead to inhibition of osteoblast and increase in osteoclast activity, which leads to bone-related issues in myeloma. Similar interactions with immune microenvironment lead to augmentation of tumor-promoting immune responses and suppression of tumor protective immune responses, overall allowing myeloma cell growth. (Adapted from G Bianchi, NC Munshi: Blood 125: 3049, 2015.) necrosis factor [TNF]). The bone lesions are lytic in nature (Fig. 116-5) and are rarely associated with osteoblastic new bone formation due to their suppression by dickkopf-1 (DKK-1) produced by myeloma cells. Therefore, radioisotopic bone scan is less useful in diagnosis than is plain radiography. The bony lysis results in substantial mobilization of calcium from bone, and serious acute and chronic complications of hypercalcemia may dominate the clinical picture (see below). Local­ ized bone lesions may cause pathological fracture or the collapse of vertebrae, leading to spinal cord compression. The next most common clinical problem in patients with myeloma is susceptibility to bacterial infections. The most common infections are pneumonias and pyelone­ phritis, and the most frequent pathogens are Streptococcus pneumoniae, Staphylococcus aureus, and Klebsiella pneumoniae in the lungs and Escherichia coli and other gram-negative organisms in the urinary tract. In ~25% of patients, recurrent infections are the presenting features, and >75% of patients will have a serious infection at some time in their course. The susceptibility to infection has several contributing causes. First, patients with myeloma have diffuse hypogammaglobulinemia if the M component is excluded. The hypogammaglobulinemia is related to both decreased production and increased destruction of normal antibodies. The large M component results in fractional catabolic rates of 8–16% instead of the normal 2%. Moreover, some patients generate a population of circulating regulatory cells in response to their myeloma that can suppress normal antibody synthesis. These patients have very poor antibody responses, especially to polysaccharide antigens such as those on bacterial cell walls. Various abnormalities in T-cell function are also observed including decreased TH1 response, increase in TH17 cells producing proinflammatory cytokines, and aberrant T regulatory MDSC pDC Anergic Exhausted Cytotoxic T cell CTLA4 PD-L1 PD-1 Proliferatic p42/44 MAPK Raf MEK BCI-xL Mcl-1 JAK STAT3 Drug resistance antiapoptosis Bad NF-κB Cyclin D PI3-K FKHR Akt p21 Cell cycle Adhesion molecule interactions Migration PKC cell function. Granulocyte lysozyme content is low, and granulocyte migration is not as rapid as normal in patients with myeloma, probably the result of a tumor product. There are also a variety of abnormalities in complement functions in myeloma patients. All these factors con­ tribute to the immune deficiency in these patients. Some commonly used therapeutic agents may significantly affect immune function; e.g., dexamethasone suppresses immune responses and increases sus­ ceptibility to bacterial and fungal infection, B-cell maturation antigen (BCMA)–targeting chimeric antigen receptor T (CAR-T) cells and bispecific antibodies can eliminate plasma cells inducing hypogamma­ globulinemia, and bortezomib predisposes to herpesvirus reactivation. Renal failure occurs in nearly 25% of myeloma patients, and some renal pathology is noted in >50%. Of many contributing factors, hypercalcemia is the most common cause of renal failure. Glomerular deposits of amyloid, hyperuricemia, recurrent infections, frequent use of nonsteroidal anti-inflammatory agents for pain control, use of iodinated contrast dye for imaging, bisphosphonate use, and occa­ sional infiltration of the kidney by myeloma cells all may contribute to renal dysfunction. However, tubular damage associated with the excretion of light chains is common. Normally, light chains are filtered, reabsorbed in the tubules, and catabolized. With the increase in the amount of light chains presented to the tubule, the tubular cells become overloaded with these proteins, and tubular damage results either directly from light chain toxic effects or indirectly from the release of intracellular lysosomal enzymes. The earliest manifestation of this tubular damage is the adult Fanconi’s syndrome (a type 2 proximal renal tubular acidosis), with loss of glucose and amino acids, as well as defects in the ability of the kidney to acidify and concentrate the urine. A B FIGURE 116-5  Bony lesions in multiple myeloma (MM). A. The skull demonstrates the typical “punched out” lesions characteristic of MM. The lesion represents a purely osteolytic lesion with little or no osteoblastic activity (above). B. Positron emission tomography/computed tomography showing multiple fluorodeoxyglucose (FDG)-avid lesions in skeleton (left panel) with their resolution on achieving complete response (CR) (right panel). (Part A courtesy of Dr. Geraldine Schechter; with permission. Part B courtesy of Dr. Sundar Jagannath; with permission.) The proteinuria is not accompanied by hypertension, and the protein is nearly all light chains. Generally, very little albumin is in the urine because glomerular function is usually normal. When the glomeruli are involved, nonselective proteinuria is also observed. Patients with myeloma also have a decreased anion gap [i.e., Na+ – (Cl− + HCO3 −)] because the M component is cationic, resulting in retention of chloride. This is often accompanied by hyponatremia that is felt to be artificial (pseudohyponatremia) because each volume of serum has less water as a result of the increased protein. Renal dysfunction due to light chain deposition disease, light chain cast nephropathy, and amyloidosis is partially reversible with effective therapy. Myeloma patients are sus­ ceptible to developing acute renal failure if they become dehydrated. Normocytic and normochromic anemia occurs in ~80% of myeloma patients. It is usually related to the replacement of normal marrow by expanding tumor cells, to the inhibition of hematopoiesis by factors produced by the tumor, to reduced production of erythropoietin by the kidney, and to the effects of long-term therapy. In addition, mild hemolysis may contribute to the anemia. A larger than expected frac­ tion of patients may have megaloblastic anemia due to either folate or vitamin B12 deficiency. Granulocytopenia and thrombocytopenia are rare except when therapy-induced. Clotting abnormalities may be seen due to the failure of antibody-coated platelets to function properly; the interaction of the M component with clotting factors I, II, V, VII, or VIII; antibody to clotting factors; or amyloid damage of endothelium. Deep venous thrombosis is also observed with the use of thalidomide, lenalidomide, or pomalidomide. Raynaud’s phenomenon and impaired circulation may result if the M component forms cryoglobulins, and hyperviscosity syndromes may develop depending on the physical properties of the M component (most common with IgM, IgG3, and IgA paraproteins). Hyperviscosity is defined based on the relative viscosity of serum as compared with water. Normal relative serum vis­ cosity is 1.8 (i.e., serum is normally almost twice as viscous as water). Symptoms of hyperviscosity occur at a level greater than 4 centipoises (cP), which is usually reached at paraprotein concentrations of ~40 g/L (4 g/dL) for IgM, 50 g/L (5 g/dL) for IgG3, and 70 g/L (7 g/dL) for IgA; however, chemico-physical properties of the paraproteins may cause it at lower levels. CHAPTER 116 Plasma Cell Disorders Although neurologic symptoms occur in a minority of patients, they may have many causes. Hypercalcemia may produce lethargy, weak­ ness, depression, and confusion. Hyperviscosity may lead to headache, fatigue, shortness of breath, exacerbation or precipitation of heart failure, visual disturbances, ataxia, vertigo, retinopathy, somnolence, and coma. Bony damage and collapse may lead to cord compression, radicular pain, and loss of bowel and bladder control. Infiltration of peripheral nerves by amyloid can be a cause of carpal tunnel syndrome and other sensorimotor mono- and polyneuropathies. Neuropathy associated with monoclonal gammopathy of undetermined signifi­ cance (MGUS) and myeloma is more frequently sensory than motor neuropathy and is associated with IgM more than other isotypes. In >50% of patients with neuropathy, the IgM monoclonal protein is directed against myelin-associated globulin (MAG). Sensory neu­ ropathy is also a side effect of therapy, specifically thalidomide and bortezomib. Many of the clinical features of myeloma, e.g., cord compression, pathologic fractures, hyperviscosity, sepsis, and hypercalcemia, can present as medical emergencies. Despite the widespread distribution of plasma cells in the body, tumor expansion is dominantly within bone and bone marrow and, for reasons unknown, rarely causes enlargement of spleen, lymph nodes, or gut-associated lymphatic tissue. ■ ■DIAGNOSIS AND STAGING The diagnosis of myeloma requires marrow plasmacytosis (>10%), a serum and/or urine M component, and at least one of the myelomadefining events detailed in Table 116-1. Bone marrow plasma cells are CD138+ and either monoclonal kappa or lambda light chain positive. The most important differential diagnosis in patients with myeloma involves their separation from individuals with MGUS or smolder­ ing multiple myeloma (SMM). MGUS is vastly more common than myeloma, occurring in 1% of the population aged >50 years and in up to 10% of individuals aged >75 years. The diagnostic criteria for MGUS, SMM, and myeloma are described in Table 116-1. Although ~1% of patients per year with MGUS go on to develop myeloma, all cases of myeloma are preceded by MGUS. Non-IgG subtype, abnormal kappa/lambda free light chain ratio, and serum M protein >15 g/L (1.5 g/dL) are associated with higher incidence of progression of MGUS to myeloma. Absence of all three features predicts a 5% chance of progres­ sion, whereas higher-risk MGUS with the presence of all three features predicts a 60% chance of progression over 20 years. The features PART 4 Oncology and Hematology TABLE 116-1  Diagnostic Criteria for Multiple Myeloma, Myeloma Variants, and Monoclonal Gammopathy of Undetermined Significance Monoclonal Gammopathy of Undetermined Significance (MGUS) Serum monoclonal protein (non-IgM type) <30 g/L Clonal bone marrow plasma cells <10%a Absence of myeloma-defining events or amyloidosis that can be attributed to the plasma cell proliferative disorder Smoldering Multiple Myeloma (Asymptomatic Myeloma) Both criteria must be met: • Serum monoclonal protein (IgG or IgA) ≥30 g/L or urinary monoclonal protein ≥500 mg per 24 h and/or clonal bone marrow plasma cells 10–60% • Absence of myeloma-defining events or amyloidosis Symptomatic Multiple Myeloma Clonal bone marrow plasma cells or biopsy-proven bony or extramedullary plasmacytomaa and any one or more of the following myeloma-defining events: • Evidence of one or more indicators of end-organ damage that can be attributed to the underlying plasma cell proliferative disorder, specifically: • Hypercalcemia: serum calcium >0.25 mmol/L (>1 mg/dL) higher than the upper limit of normal or >2.75 mmol/L (>11 mg/dL) • Renal insufficiency: creatinine clearance <40 mL/minb or serum creatinine >177 μmol/L (>2 mg/dL) • Anemia: hemoglobin value of >20 g/L below the lower limit of normal, or a hemoglobin value <100 g/L • Bone lesions: one or more osteolytic lesions on skeletal radiography, CT, or PET-CTc • Any one or more of the following biomarkers of malignancy: • Clonal bone marrow plasma cell percentagea ≥60% • Involved: uninvolved serum free light chain ratiod ≥100 • >1 focal lesion on MRI studiese Nonsecretory Myeloma No M protein in serum and/or urine with immunofixationf Bone marrow clonal plasmacytosis ≥10% or plasmacytomaa Myeloma-related organ or tissue impairment (end-organ damage, as described above) Solitary Plasmacytoma Biopsy-proven solitary lesion of bone or soft tissue with evidence of clonal plasma cells Normal bone marrow with no evidence of clonal plasma cellsa Normal skeletal survey and MRI (or CT) of spine and pelvis (except for the primary solitary lesion) Absence of end-organ damage such as hypercalcemia, renal insufficiency, anemia, or bone lesions (CRAB) that can be attributed to a lymphoplasma cell proliferative disorder POEMS Syndrome All of the following four criteria must be met: 1. Polyneuropathy 2. Monoclonal plasma cell proliferative disorder 3. Any one of the following: (a) sclerotic bone lesions; (b) Castleman’s disease; (c) elevated levels of vascular endothelial growth factor (VEGF) 4. Any one of the following: (a) organomegaly (splenomegaly, hepatomegaly, or lymphadenopathy); (b) extravascular volume overload (edema, pleural effusion, or ascites); (c) endocrinopathy (adrenal, thyroid, pituitary, gonadal, parathyroid, and pancreatic); (d) skin changes (hyperpigmentation, hypertrichosis, glomeruloid hemangiomata, plethora, acrocyanosis, flushing, and white nails); (e) papilledema; (f) thrombocytosis/polycythemiag aClonality should be established by showing κ/λ light chain restriction on flow cytometry, immunohistochemistry, or immunofluorescence. Bone marrow plasma cell percentage should preferably be estimated from a core biopsy specimen; in case of a disparity between the aspirate and core biopsy, the highest value should be used. bMeasured or estimated by validated equations. CIf bone marrow has <10% clonal plasma cells, more than one bone lesion is required to distinguish from solitary plasmacytoma with minimal marrow involvement. dThese values are based on the serum Freelite assay (The Binding Site Group, Birmingham, United Kingdom). The involved free light chain must be ≥100 mg/L. eEach focal lesion must be ≥5 mm in size. fA small M component may sometimes be present. gThese features should have no other attributable causes and have temporal relation with each other. Abbreviations: CT, computed tomography; MRI, magnetic resonance imaging; PET-CT, 18F-fluorodeoxyglucose positron emission tomography with computed tomography; POEMS, polyneuropathy, organomegaly, endocrinopathy, M-protein, and skin changes. responsible for higher risk of progression from SMM to MM are bone marrow plasmacytosis >10%, abnormal kappa/lambda free light chain ratio, and serum M protein >30 g/L (3 g/dL). Patients with only one of these three features have a 25% chance of progression to MM in 5 years, whereas patients with high-risk SMM with all three features have a 76% chance of progression. Two important variants of myeloma are solitary bone plasmacytoma and solitary extramedullary plasmacy­ toma. These lesions are associated with an M component in <30% of the cases, they may affect younger individuals, and both are associated with median survivals of ≥10 years. Solitary bone plasmacytoma is a single lytic bone lesion without marrow plasmacytosis. Extramedullary plasmacytomas usually involve the submucosal lymphoid tissue of the nasopharynx or paranasal sinuses without marrow plasmacytosis. Both tumors are highly responsive to local radiation therapy. If an M com­ ponent is present, it should disappear after treatment. Solitary bone plasmacytomas may recur in other bony sites or evolve into myeloma. Extramedullary plasmacytomas rarely recur or progress. ■ ■LABORATORY INVESTIGATION Serum protein electrophoresis and measurement of serum immuno­ globulins and free light chains are useful for detecting and character­ izing M spikes, supplemented by immunoelectrophoresis, which is especially sensitive for identifying low concentrations of M compo­ nents not detectable by protein electrophoresis. A 24-h urine specimen is necessary to quantitate Bence Jones protein (immunoglobulin light chain) excretion. The serum M component is IgG in 53% of patients, IgA in 25%, and IgD in 1%; 20% of patients will have only light chains in serum and urine. Dipsticks for detecting proteinuria are not reli­ able at identifying light chains, and the heat test for detecting Bence Jones protein is falsely negative in ~50% of patients with light chain myeloma. Fewer than 1% of patients have no identifiable M compo­ nent; these patients usually have light chain myeloma in which renal catabolism has made the light chains undetectable in the urine. In most of these patients, light chains can now be detected by serum free light chain assay. Mass spectrometry has been investigated to accurately assess M protein. IgD myeloma may also present with light chain disease. About two-thirds of patients with serum M components also have urinary light chains. The light chain isotype may have an impact on disease behavior. Whether this is due to some genetically important determinant of cell proliferation or because lambda light chains are more likely to cause renal damage and form amyloid than are kappa light chains is unclear. About half of patients with IgM paraproteins develop hyperviscosity compared with only 2–4% of patients with IgA and IgG M components. Among IgG myelomas, it is the IgG3 subclass that has the highest tendency to form both concentration- and temperature-dependent aggregates, leading to hyperviscosity and cold agglutination at lower serum concentrations. A standard workup directed at detecting monoclonal plasma cells and myeloma-defining events as well as prognosis is detailed in Table 116-2. A complete blood count with differential may reveal anemia. Eryth­ rocyte sedimentation rate is elevated. Rare patients (~1%) may have plasma cell leukemia with >2000 plasma cells/μL. This may be seen in disproportionate frequency in IgD (12%) and IgE (25%) myelomas. Serum calcium, urea nitrogen, creatinine, and uric acid levels may be elevated. Serum alkaline phosphatase is usually normal even with extensive bone involvement because of the absence of osteoblastic activity. It is also important to quantitate serum β2-microglobulin and albumin (see below). Chest and bone radiographs may reveal lytic lesions or diffuse osteo­ penia. Magnetic resonance imaging (MRI) offers a sensitive means to document extent of bone marrow infiltration and cord or root com­ pression in patients with pain syndromes. 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)/computed tomogra­ phy (CT) is a valuable tool to assess bone damage and detect extramed­ ullary sites of the disease (Fig. 116-5). The use of 18F-FDG PET/CT is now considered standard to distinguish between smoldering and active TABLE 116-2  Standard Investigative Workup in Multiple Myeloma (MM) Investigations to Evaluate for Clonal Plasma Cells Bone marrow aspirate and biopsy (fine-needle aspiration of plasmacytoma if indicated) • Histology • Clonality by kappa/lambda immunostaining by flow cytometry or immunohistochemistry Investigations to Evaluate Clonal Paraprotein Serum protein electrophoresis and immunofixation Quantitative serum immunoglobulin levels (IgG, IgA, and IgM) 24-h urine protein electrophoresis and immunofixation Serum free light chain and ratio Immunofixation for IgD or IgE in select cases Investigation to Evaluate End-Organ Damage Hemogram to assess for anemia. Chemistry panel for renal function and calcium Skeletal survey or PET/CT scan to evaluate bone lesions PET/CT or MRI if smoldering MM or solitary plasmacytoma Investigation for Risk Stratification β2-Microglobulin and serum albumin for ISS stage DNA-sequencing or if not available Fluorescent in situ hybridization for hyperdipoidy, del17p, t(4;14); t(11;14), t(14;16), t(14;20), amp1q34, and del1p and p53 mutation on bone marrow sample LDH Specialized Investigation in Selected Cases Abdominal fat pad for amyloid Serum viscosity if IgM component or high IgA levels or serum M component >7 g/dL Myd88 and CXCR4 mutation analysis if IgM component Abbreviations: CT, computed tomography; ISS, International Staging System; LDH, lactate dehydrogenase; MRI, magnetic resonance imaging; PET/CT, positron emission tomography/computed tomography. MM and to confirm a suspected diagnosis of solitary plasmacytoma. It is also a valuable tool to evaluate response in patients with oligo- or nonsecretory myeloma. ■ ■PROGNOSIS Serum β2-microglobulin is the single most powerful predictor of sur­ vival and can substitute for staging. β2-Microglobulin is the light chain of the class I major histocompatibility antigens (HLA-A, -B, -C) on the surface of every cell. Combination of serum β2-microglobulin and albumin levels forms the basis for a three-stage International Staging System (ISS) (Table 116-3) that predicts survival. With the use of highdose therapy and the newer agents, the Durie-Salmon staging system is unable to predict outcome and is no longer used. High labeling index, circulating plasma cells, performance status, and high levels of lactate dehydrogenase are also associated with poor prognosis. With low proliferative activity of plasma cells, karyotype is now not recommended in myeloma. Fluorescent in situ hybridization (FISH) has become a standard investigative technique, and the current recom­ mendation suggests switching to DNA sequencing-based methods. Chromosome 17p deletion with 20% clonality or TP53 mutation, and translocations t(4;14), (14;16), or t(14;20) associated with del 1p or amp1q changes along with high β2-microglobulin with normal renal function are considered prognostic for high-risk disease, as described in Table 116-3. Chromosome 13q deletion and t(11;14) are not consid­ ered predictors of high-risk myeloma. CHAPTER 116 TREATMENT Multiple Myeloma Plasma Cell Disorders MGUS, SMM, AND SOLITARY PLASMACYTOMA No specific intervention is indicated for patients with MGUS. Follow-up once a year or less frequently is adequate except in higher-risk MGUS, where serum protein electrophoresis, complete blood count, creatinine, and calcium should be repeated every 6 months. A patient with MGUS and severe polyneuropathy is con­ sidered for therapeutic intervention if a causal relationship can be assumed, especially in the absence of any other potential causes for neuropathy. Therapy can include plasmapheresis and occasionally rituximab in patients with IgM MGUS or myeloma-like therapy TABLE 116-3  Risk Stratification in Myeloma STANDARD RISK (75–80%) (EXPECTED SURVIVAL 8–10+ YEARS) HIGH RISK (20–25%) (EXPECTED SURVIVAL 3–4 YEARS) METHOD DNA sequencing or FISH if sequencing not available t(11;14) del(17p) (20% cutoff) and/ or TP53 mut   del(13) t(4;14)/t(14;16)/t(14;20) with 1q gain and/or 1p del   Hyperdiploidy Del 1p + 1q gain or biallelic del 1p Biochemical assessment   β2M >5.5 with normal creatinine INTERNATIONAL STAGING SYSTEM (ISS) INTERNATIONAL STAGING SYSTEM (ISS) STAGE MEDIAN SURVIVAL, MONTHS β2M <3.5, ALB ≥3.5 I (28%) II (39%) β2M <3.5, ALB <3.5 or β2M <3.5, ALB ≥3.5 or β2M = 3.5–5.5 III (33%) β2M >5.5 or β2M <3.5, ALB <3.5 or β2M = 3.5–5.5 aPercentage of patients presenting at each stage. Abbreviations: β2M, serum β2-microglobulin in mg/L; ALB, serum albumin in g/dL; FISH, fluorescent in situ hybridization; LDH, lactate dehydrogenase. in those with IgG or IgA disease. A subset of patients with MGUS develop renal dysfunction usually based on renal damage from the monoclonal antibody. The damage may affect the glomeruli, tubules, or vessels. No consensus exists on management, but lower­ ing the level of the monoclonal antibody with bortezomib has had some advocates. About 10% of patients have SMM and will have an indolent course demonstrating only slow progression of disease over many years. For patients with SMM, no specific therapeutic intervention is indicated in general. But early intervention with lenalidomide alone or in combination with dexamethasone has been shown to prevent progression from high-risk SMM to active MM. At present, patients with SMM only require antitumor therapy when myelomadefining events are identified. Patients with solitary bone plasmacytomas and extramedullary plasmacytomas may be expected to enjoy prolonged disease-free survival after local radiation therapy at a dose of ~40 Gy. Occult marrow involvement may occur at low incidence in patients with TABLE 116-4  Standard Therapeutic Agents in Myeloma CLASS AGENT STANDARD DOSAGE AND ADMINISTRATION COMBINATION MYELOMA INDICATION Immunomodulatory drugs (IMiD) Thalidomide (T) Oral 50–200 mg qd TD, VTD Newly diagnosed and relapsed PART 4 Oncology and Hematology Lenalidomide (R) Oral 5–25 mg daily × 21 days q 4 weeks RD, RVD, DaRD, ERD, KRD, IRD, DaRVD Pomalidomide (P) Oral 2–4 mg daily × 21 days q 4 weeks PD, KPD, DaPD Relapsed Proteasome inhibitors (PI) Bortezomib (V) IV or SC 1.3 mg/m2 days 1, 4, 8, 11 OR days 1, 8, 15 VD, VTD, VRD, DaVD, VCD DaRVD Carfilzomib (K) IV 20–56 mg/m2 days 1, 2, 8, 9, 15, 16 q 4 weeks KD, KRD, KPD, Da KD, Da KRD, IsaKD Ixazomib (I) Oral 4 mg days 1, 8, 15 IRD Relapsed, maintenance Antibodies Daratumumab (Da) IV or SC 16 mg/kg per week for 8 weeks then every 2 weeks for 16 weeks and then every 4 weeks thereafter Elotuzumab (E) IV 10 mg/kg days 1, 8, 15, and 22 for first two cycles, then on days 1 and 15; along with RD Isatuximab (Isa) IV 10 mg/kg weekly for 4 weeks and then every 2 weeks Belantamab mafodotin IV 2.5 mg/kg once every 3 weeks   Relapsed or refractory—4 prior lines of therapy Selective inhibitor of nuclear export (SINE) Selinexor (S) Oral 80 mg on days 1 and 3 of each week SVD Relapsed Histone deacetylase inhibitor Panobinostat (Pa) Oral 20 mg once every other day for 3 doses/week for 2 weeks every 21 days Alkylating agents Melphalan (M) Oral 0.25 mg/kg per day for 4 days (with P) every 4–6 weeks Cyclophosphamide IV—300–500 mg/m2 weekly × 2 q 4 weeks Oral—50 mg qd × 21 days Bendamustine (B) IV 70–90 mg days 1, 2 OR days 1, 8 q 4 weeks BD or BVD Relapsed Melflufen (Me) IV 40 mg day 1 (with D 40 mg on days 1, 8, 15, and 22) q 28 days Glucocorticoid Dexamethasone (D) Prednisone (P) Oral 10–40 mg q week Oral 1 mg/kg Cellular therapy Idecabtagene vicleucel (Ide-cel) IV 450 × 106 cells None At least two prior lines of therapy that includes an PI, IMiD and anti-CD38 antibody Ciltacabtagene autoleucel (Cilta-cel) IV None At least one prior line of therapy, including PI and IMiD and who are refractory to lenalidomide Bispecific antibodies Teclistamab Anti-BCMA–anti-CD3 Step-up doses of 0.06 mg and 0.3 mg per kilogram SC days 1, 4 and 1.5 mg per kilogram of body weight day 8 and q week None Relapsed or refractory—4 prior lines of therapy with prior exposure to PI, IMiD, and anti-CD38 antibody Elranatamab Anti-BCMA–anti-CD3 Step-up doses of 12 and 32 mg on days 1, 4 and 76 mg SC day 8 and then q week for 25 weeks and then q 2 weeks Talquetamab Anti-GPRC5D–anti-CD3 Two step-up doses during first week and then every week or every other week regimen solitary bone plasmacytoma. Such patients are usually identified because their serum M component falls slowly or disappears ini­ tially after local therapy, only to return after a few months. These patients respond well to systemic therapy. SYMPTOMATIC MM Patients with symptomatic myeloma require therapeutic inter­ vention. In general, such therapy has two purposes: (1) systemic therapy to control myeloma; and (2) supportive care to control symptoms of the disease, its complications, and adverse effects of therapy. Therapy can significantly prolong survival and improve the quality of life for myeloma patients. The therapy of myeloma includes an initial induction regimen followed by consolidation and/or maintenance therapy and, on subsequent progression, management of relapsed disease. All agents available for use at various stages of the therapy and their doses, schedules, and combinations are detailed in Table 116-4. Therapy is partly dictated by the patient’s age and comorbidities, which may Newly diagnosed, maintenance, and relapsed Newly diagnosed and relapsed Newly diagnosed and relapsed Dara, DaRD, DaVD, DaPD, DaKD Newly diagnosed, maintenance, and relapsed ERD, EPD Relapsed IsaPD, IsaKD Relapsed PaVD Relapsed MP, MPT, MPR, MPV, DaMPV, high-dose M Newly diagnosed and relapsed conditioning VCD Newly diagnosed and relapsed MeD Relapsed or refractory—4 prior lines of therapy   All stages None None Newly diagnosed Smoldering myeloma No therapy except on clinical study or high-risk – Regular follow-up Myeloma-defining events Yes Transplant eligible Transplant ineligible* Induction therapy 4-drug regimen with Dara, R, V or K and d; 3-drug regimen without Dara, or VCd until maximum effect No response Alternate regimen Response HDT with ASCT/ consolidation No response Relapse Relapse Maintenance Treatment of relapsed disease 2–4 line of alternate regimen *Due to age or comorbidities. FIGURE 116-6  Treatment algorithm for multiple myeloma. Alternate regimen indicates combinations including daratumumab, elotuzumab, panobinostat, carfilzomib, ixazomib, pomalidomide, or other agents. ASCT, autologous stem cell transplantation; C, cyclophosphamide; D, dexamethasone; HDT, high-dose therapy; M, melphalan; MDE, myeloma-defining events; P, prednisone; R, lenalidomide; RVD-lite, weekly regimen; V, bortezomib. affect a patient’s ability to undergo high-dose therapy and trans­ plantation (Fig. 116-6). Three important classes of agents approved for treatment of newly diagnosed MM are immunomodulatory agents, proteasome inhibitors, and antibodies targeting CD38. The combination of lenalidomide with a proteasome inhibitor (bortezomib or carfil­ zomib) and dexamethasone achieves close to a 100% response rate and a >50% complete response (CR) rate, making this combina­ tion one of the preferred induction regimens in transplant-eligible patients. Other similar three-drug combinations (bortezomib, tha­ lidomide, and dexamethasone or bortezomib, cyclophosphamide, and dexamethasone) also achieve >90% response rate. Addition of a fourth agent, daratumumab or isatuximab, an anti-CD38 antibody, is providing even deeper responses and such four-drug regimens as induction therapy are becoming standard of care. Usually between four and six cycles of these combination regimens are utilized to achieve initial deep cytoreduction before consideration of highdose therapy with autologous stem cell transplantation. In patients who are not transplant candidates due to physiologic age >70 years, significant cardiopulmonary problems, or other comorbid illnesses, the same three-drug combinations described above are considered standard of care as induction therapy with age- and frailty-guided dose and schedule modifications. Com­ bination of daratumumab with lenalidomide and dexamethasone (DRd) and modified lenalidomide-bortezomib-dexamethasone (RVD lite) combination achieve high overall response rates (93 and 86%, respectively) and CR rates (47 and 32%, respectively). The four-drug combinations used in younger patients are also utilized in healthy older patients with excellent response. In the past, the combination of melphalan with prednisone (MP) alone or with thalidomide or bortezomib has been utilized effectively, but with the availability of newer agents and combinations, MP-based com­ binations are now not utilized. No If appearance of MDE Induction therapy 4-drug regimen with Dara, R, V or K and d, Dara Rd, RVd-lite, VCd, Vd, Rd, VMP until maximum effect Response CHAPTER 116 Maintenance Treatment of relapsed disease: 5th line and beyond alternate regimen Plasma Cell Disorders HIGH-DOSE THERAPY WITH AUTOLOGOUS STEM CELL TRANSPLANTATION High-dose therapy (HDT) and consolidation/maintenance are stan­ dard practice in the majority of eligible patients. In patients who are transplant candidates and receiving lenalidomide, stem cells should be collected within 6 months because the continued use of lenalidomide may compromise the ability to collect adequate numbers of stem cells. Randomized studies comparing standarddose therapy to high-dose melphalan therapy with hematopoietic stem cell support have shown that HDT can achieve higher overall response rates, with up to 25–40% additional CRs and prolonged progression-free and overall survival; however, few, if any, patients are cured. Although two successive HDTs (tandem transplanta­ tions) are more effective than single HDT, the benefit is only observed in the subset of patients who do not achieve a complete or very good partial response to the first transplantation, which is a rare subset. Moreover, a randomized study failed to show any sig­ nificant difference in overall survival between early transplantation after induction therapy versus delayed transplantation at relapse. These data allow an option to delay transplantation, especially with the availability of newer agents and combinations. Allogeneic transplantations may also produce high response rates, but with significant toxicities. Nonmyeloablative allogeneic transplantation can reduce toxicity but is recommended only under the auspices of a clinical trial to exploit an immune graft-versus-myeloma effect while avoiding attendant toxicity. Due to effective cellular therapies, allogeneic transplantation is very rarely used. Maintenance therapy prolongs remissions following standarddose regimens as well as HDT. Several phase 3 studies have demonstrated improved progression-free survival, and one study showed prolonged overall survival in patients receiving lenalido­ mide compared to placebo as maintenance therapy after HDT. In nontransplant candidates, two phase 3 studies showed prolonged progression-free survival with lenalidomide maintenance after MP plus lenalidomide or lenalidomide plus dexamethasone induction therapy. Although concern arises regarding an increased incidence of second primary malignancies in patients receiving lenalidomide maintenance, its benefits in reducing the risk of progressive disease and death from myeloma far outweigh the small increased risk of second cancers. In patients with high-risk cytogenetics, lenalido­ mide and bortezomib or an oral proteasome inhibitor, ixazomib, show promise as maintenance combination therapy after trans­ plantation. A phase 3 study has also demonstrated the benefit of maintenance therapy with daratumumab after HDT. RELAPSED DISEASE Relapsed myeloma can be treated with a number of agents includ­ ing lenalidomide and/or bortezomib, if previously not used. The second-generation proteasome inhibitor carfilzomib and immuno­ modulatory agent pomalidomide have shown efficacy in relapsed and refractory MM, even MM refractory to lenalidomide and bortezomib. An oral proteasome inhibitor, ixazomib, has also been approved in combination with lenalidomide and dexamethasone as an all-oral regimen for relapsed MM. Four antibodies are approved for treatment of relapsed MM. Daratumumab targeting CD38 achieves high response rates and improved progression-free sur­ vival as a single agent with further improvement in response and survival when added to bortezomib and dexamethasone or lenalidomide and dexamethasone. A formulation of daratumumab for subcutaneous administration provides decreased toxicity and improved convenience. Isatuximab, another antibody targeting CD38, achieves high response rates and improved progression-free survival in combination with pomalidomide or carfilzomib and dexamethasone. Elotuzumab, which targets SLAMF7, has shown significant activity in combination with lenalidomide and dexa­ methasone in relapsed/refractory myeloma but not as a single agent. Finally, belantamab mafodotin, an antibody-drug conjugate, targets B-cell maturation antigen (BCMA), which is expressed mainly on normal plasma cells and myeloma cells and delivers auristatin, a microtubule inhibitor, to the tumor cells and achieves responses in relapsed/refractory myeloma. The drug has a unique ophthalmo­ logic toxicity that requires close monitoring. Its efficacy increases significantly when combined with pomalidomide or proteasome inhibitor. PART 4 Oncology and Hematology Panobinostat, a histone deacetylase inhibitor, in combination with bortezomib and dexamethasone has been approved for treat­ ment of relapsed/refractory myeloma based on superior response and progression-free survival compared to bortezomib and dexa­ methasone alone. Two additional newer agents have unique mecha­ nisms of action: selinexor is a first-in-class exportin inhibitor that blocks export of proteins from the cell nucleus, and melflufen is an alkylating agent conjugated to a peptide to improve specific delivery to myeloma cells that express aminopeptidase required for cleaving of the peptide to deliver the drug intracellularly in myeloma cells. Both agents have been approved based on their effectiveness in relapsed/refractory myeloma. Immunotherapeutic Approaches  Two cellular therapies, both tar­ geting BCMA, are approved for relapsed myeloma. The anti-BCMA CAR transduced T cell, idecabtagene vicleucel (Ide-cel), is approved after at least two prior lines of therapy that includes an immu­ nomodulatory agent, a proteasome inhibitor, and an anti-CD38 monoclonal antibody, whereas ciltacabtagene autoleucel (Cilta-cel) is approved for patients who have received at least one prior line of therapy, including a proteasome inhibitor and an immunomodula­ tory agent and who are refractory to lenalidomide. In patients with advanced myeloma with a median of six prior lines of treatment, 81% of patients receiving target dose of Ide-cel responded, and a CR rate of 33% was observed. Cilta-cel in a similar patient population achieved 98% overall response with 82% achieving CR. Cytokine release syndrome and neurotoxicity remain primary toxicities requiring close monitoring and aggressive management. Three bispecific antibodies are also approved for treatment of relapsed and refractory myeloma after four prior lines of thera­ pies. Bispecific antibodies can bind to two different cell surface targets through two distinct binding domains. One domain binds to CD3 on human lymphocytes, while the other domain binds to a cell surface target specific for myeloma cells, bringing the T cells closer and leading to myeloma cell death. Two bispecific antibodies, teclistamab and elranatamab, target BCMA, whereas talquetamab targets a novel cell surface target on myeloma cells, G protein– coupled receptor class C group 5 (GPRC5D). In patients with relapsed refractory myeloma, these antibodies result in a 60–70% response rate, with a quarter of the patients achieving CR. Bispecific antibodies are associated with toxicities including cytokine release syndrome, neurotoxicity, and significant susceptibility to infectious complications. Incorporation of the large number of active agents at various stages of treatment, including in newly diagnosed patients, is improving survival as well as quality of life. THERAPY ENDPOINT Improvement in the serum M component may lag behind the symp­ tomatic improvement due to longer serum half-life (~3 weeks) of the immunoglobulin. The fall in M component depends on the rate of tumor kill and the fractional catabolic rate of immunoglobulin. Serum and urine light chains with a functional half-life of ~6 h may fall much quicker within the first week of treatment. Because urine light chain levels may relate to renal tubular function, they are not a reliable measure of tumor cell kill in patients with renal dysfunc­ tion. Achieving CR, defined as disappearance of serum and urine monoclonal protein with normal bone marrow by light microscopy, has been a standard goal of therapy. However, sequencing or multi­ color flow cytometry–based assessment of minimal residual disease (MRD) in bone marrow to measure the presence of one myeloma cell in a million cells is being considered as an important new end­ point, both in newly diagnosed and relapsed patients. Absence of MRD at this sensitivity predicts for both longer progression-free survival and longer overall survival. Although patients may not achieve complete remission, clinical responses may last for long periods of time in small numbers of patients. The median overall survival of patients with myeloma is 8+ years, with subsets of younger patients surviving >10 years. The major causes of death are progressive myeloma, renal failure, sepsis, or therapy-related myelodysplasia. Nearly a quarter of patients die of myocardial infarction, chronic lung disease, diabetes, or stroke, which are all intercurrent illnesses related more to the age of the patient group than to the tumor. SUPPORTIVE THERAPY Herpes zoster prophylaxis is indicated if bortezomib is used, and neuropathy attendant to bortezomib can be decreased both by its subcutaneous administration and by administration on a weekly schedule. Lenalidomide use requires prophylaxis for deep-vein thrombosis (DVT) with either aspirin or, if patients are at a greater risk of DVT, warfarin, low-molecular-weight heparin, or direct-acting anticoagulants DOACs. Patients receiving anti-BCMA CAR-T cell therapy or bi-specific antibodies may need supplemen­ tation with intravenous γ globulin due to induction of prolonged hypogammaglobulinemia. Supportive care directed at the anticipated complications of the disease may be as important as primary antitumor therapy. Hypercalcemia generally responds well to bisphosphonates, glu­ cocorticoid therapy, hydration, and natriuresis and rarely requires calcitonin as well. Bisphosphonates (e.g., pamidronate 90 mg or zoledronate 4 mg initially once a month for 12–24 months and later every 2–3 months) reduce osteoclastic bone resorption and pre­ serve performance status and quality of life, decrease bone-related complications, and may also have antitumor effects. Osteonecrosis of the jaw and renal dysfunction can occur in a minority of patients receiving bisphosphonate therapy. Denosumab is an alternative agent administered intravenously at 120 mg monthly and achieves a similar level of effect as bisphosphonates to prevent bone-related complications in myeloma. Treatments aimed at strengthening the skeleton such as fluorides, calcium, and vitamin D, with or without androgens, have been suggested but are not of proven efficacy. Kyphoplasty or vertebroplasty should be considered in patients with painful collapsed vertebra. Iatrogenic worsening of renal function may be prevented by maintaining a high fluid intake to prevent dehydration and enhance excretion of light chains and calcium. In the event of acute renal failure, plasmapheresis is ~10 times more effective at clearing light chains than peritoneal dialysis; however, its role in reversing renal failure remains controversial. Importantly, reducing the protein load by effective antitumor therapy with agents such as bortezomib may result in improvement in renal function in over half of the patients. Use of lenalidomide in renal failure is pos­ sible but requires dose modification because it is renally excreted. Urinary tract infections should be watched for and treated early. Plasmapheresis may be the treatment of choice for hyperviscosity syndromes. Although the pneumococcus is a dreaded pathogen in myeloma patients, pneumococcal polysaccharide vaccines may not elicit an antibody response. The pneumococcal conjugate vaccines are more protective. Prophylactic administration of intravenous γ globulin preparations is used in the setting of recurrent serious infections and in patients receiving CAR-T therapy or bispecific antibodies. Routine chronic oral antibiotic prophylaxis is not war­ ranted. Patients receiving bortezomib or CD38-directed therapies receive prophylaxis against herpes zoster. Patients with myeloma and even SMM and MGUS may be at a higher risk of developing COVID-19 and thus are encouraged to have vaccination for preven­ tion and, if positive for infection, to receive antiviral therapy for COVID-19. Patients developing neurologic symptoms in the lower extremities, severe localized back pain, or problems with bowel and bladder control may need emergency MRI and local radiation therapy and glucocorticoids if cord compression is identified. In patients in whom neurologic deficit is increasing or substantial, emergent surgical decompression may be necessary. Most bone lesions respond to analgesics and systemic therapy, but certain pain­ ful lesions may respond more promptly to localized radiation. The anemia associated with myeloma may respond to erythropoietin along with hematinics (iron, folate, cobalamin). The pathogenesis of the anemia should be established and specific therapy instituted, whenever possible. WALDENSTRÖM’S MACROGLOBULINEMIA In 1948, Waldenström described a malignancy of lymphoplasmacy­ toid cells that secreted IgM. In contrast to myeloma, the disease was associated with lymphadenopathy and hepatosplenomegaly, but the major clinical manifestation was hyperviscosity syndrome. The dis­ ease resembles the related diseases CLL, myeloma, and lymphocytic lymphoma. It originates from a post–germinal center B cell that has undergone somatic mutations and antigenic selection in the lymphoid follicle and has the characteristics of an IgM-bearing memory B cell. Waldenström’s macroglobulinemia (WM) and IgM myeloma follow a similar clinical course, but therapeutic options are different. The diag­ nosis of IgM myeloma is usually reserved for patients with lytic bone lesions and predominant infiltration with CD138+ plasma cells usually with t(11;14) translocation in the bone marrow. Such patients are at greater risk of pathologic fractures than patients with WM. A familial occurrence is common in WM, but its molecular bases are yet unclear. A distinct MYD88 L265P somatic mutation is present in >90% of patients with WM and the majority of IgM MGUS. Other commonly occurring mutations include CXCR4 (30–40%), ARID1A (17%), and CD79B (8–15%). Presence of MYD88 mutation status is now used as a diagnostic test to discriminate WM from marginal zone lymphomas (MZLs), IgM-secreting myeloma, and CLL with plasma­ cytic differentiation. This mutation also explains the molecular patho­ genesis of the disease with involvement of Toll-like receptor (TLR) and interleukin 1 receptor (IL-1R) signaling leading to activation of IL-1R– associated kinase (IRAK) 4 and IRAK1 followed by nuclear factor-κB (NF-κB) activation. MYD88 mutation also triggers Bruton’s tyrosine kinase (BTK) and hemopoietic cell kinase (HCK)-mediated growth and survival signaling, which are now important therapeutic targets in WM. CXCR4 mutations induce AKT and extracellular regulated kinase 1/2 (ERK1/2) signaling. This pathway can lead to development of drug resistance in the presence of its ligand CXCL12. The disease is similar to myeloma in being slightly more com­ mon in men and occurring with increased incidence with increasing age (median age 64 years). The IgM in some patients with macro­ globulinemia may have specificity for myelin-associated glycoprotein (MAG), a protein that has been associated with demyelinating disease of the peripheral nervous system and may be lost earlier and to a greater extent than the better-known myelin basic protein in patients with multiple sclerosis. Sometimes patients with macroglobulinemia develop a peripheral neuropathy, and half of these patients are positive for anti-MAG antibody. The neuropathy may precede the appearance of the neoplasm. The whole process may begin with a viral infection that may elicit an antibody response that cross-reacts with a normal tissue component. Like myeloma, the disease involves the bone marrow, but unlike myeloma, it does not cause bone lesions or hypercalcemia. Bone mar­ row shows >10% infiltration with lymphoplasmacytic cells (surface IgM+, CD19+, CD20+, and CD22+, rarely CD5+, but CD10− and CD23−) with an increase in number of mast cells. Like myeloma, an M component is present in the serum in excess of 30 g/L (3 g/dL), but unlike myeloma, the size of the IgM paraprotein results in little renal excretion, and only ~20% of patients excrete light chains. Therefore, renal disease is not common. The light chain isotype is kappa in 80% of the cases. Patients present with weakness, fatigue, and recurrent infec­ tions similar to myeloma patients, but epistaxis, visual disturbances, and neurologic symptoms such as peripheral neuropathy, dizziness, headache, and transient paresis are much more common in macro­ globulinemia. Presence of MYD88 and CXCR4 mutations also affects disease presentation. Presence of CXCR4 mutations is associated with higher bone marrow disease burden and higher incidence of hyper­ viscosity. Patients with wild-type MYD88 show lower bone marrow disease burden. CHAPTER 116 Plasma Cell Disorders Physical examination reveals adenopathy and hepatosplenomegaly, and ophthalmoscopic examination may reveal vascular segmentation and dilation of the retinal veins characteristic of hyperviscosity states. Patients may have a normocytic, normochromic anemia, but rouleaux formation and a positive Coombs test are much more common than in myeloma. Malignant lymphocytes are usually present in the peripheral blood. About 10% of macroglobulins are cryoglobulins. These are pure M components and are not the mixed cryoglobulins seen in rheuma­ toid arthritis and other autoimmune diseases. Mixed cryoglobulins are composed of IgM or IgA complexed with IgG, for which they are specific. In both cases, Raynaud’s phenomenon and serious vascular symptoms precipitated by the cold may occur, but mixed cryoglobu­ lins are not commonly associated with malignancy. Patients suspected of having a cryoglobulin based on history and physical examination should have their blood drawn into a warm syringe and delivered to the laboratory in a container of warm water to avoid errors in quantitating the cryoglobulin. TREATMENT Waldenström’s Macroglobulinemia A diagnosis of WM requires lymphoplasmacytic infiltrate of any level in the bone marrow and an IgM monoclonal paraprotein of any size. Treatment is usually not initiated unless the disease is symptomatic or increasing anemia, hyperviscosity, lymphadenopa­ thy, or hepatosplenomegaly is present. Control of serious hypervis­ cosity symptoms such as an altered state of consciousness or paresis can be achieved acutely by plasmapheresis because 80% of the IgM paraprotein is intravascular. The median survival of affected individuals is ~50 months. However, many patients with WM have indolent disease that does not require therapy. Pretreatment parameters including older age, male sex, general symptoms, and cytopenias define a high-risk population. BTK inhibitors (ibruti­ nib), alkylating drugs (bendamustine and cyclophosphamide), and proteasome inhibitors (bortezomib, carfilzomib, and ixazomib), alone or more frequently in combination with rituximab, are con­ sidered as first-line therapy for symptomatic patients with WM. Ibrutinib targets the constitutively activated BTK. In patients with one prior line of therapy, the overall response to ibrutinib was 91%. Best responses to ibrutinib are observed in patients with mutated MYD88 and wild-type CXCR4 status, while delayed and lower response rates to ibrutinib are observed in patients with mutated CXCR4. At first relapse, in patients with an initial durable response, either the previous regimen or another primary therapy regimen can be used. The therapeutic choice is dependent upon the genomic features, drug availability, and the patient’s clinical profile. Rituximab can produce an IgM flare, so either plasmapher­ esis should be used before rituximab or its use should be initially withheld in patients with high IgM levels. Fludarabine (25 mg/m2 per d for 5 days every 4 weeks) is also an effective single agent. With identification of the MYD88 mutation, novel BTK inhibitors (acalabrutinib, zanubrutinib, and tirabrutinib), inhibitors targeting IRAK1/4, and the BCL2 antagonist venetoclax are being explored for the treatment of WM. HDT plus autologous transplantation has been utilized in the past, but it is now not recommended due to the availability of other effective agents. PART 4 Oncology and Hematology POEMS SYNDROME The features of this syndrome are polyneuropathy, organomegaly, endocrinopathy, M-protein, and skin changes (POEMS). Diagnostic criteria are described in Table 116-1. Patients usually have a severe, progressive sensorimotor polyneuropathy associated with sclerotic bone lesions from myeloma. Polyneuropathy occurs in ~1.4% of myelomas, but the POEMS syndrome is only a rare subset of that group. Unlike typical myeloma, hepatomegaly and lymphadenopathy occur in about two-thirds of patients, and splenomegaly is seen in onethird. The lymphadenopathy frequently resembles Castleman’s disease histologically, a condition that has been linked to IL-6 overproduction. The endocrine manifestations include amenorrhea in women and impotence and gynecomastia in men. Hyperprolactinemia due to loss of normal inhibitory control by the hypothalamus may be associated with other central nervous system manifestations such as papilledema and elevated cerebrospinal fluid pressure and protein. Type 2 diabetes mellitus occurs in about one-third of patients. Hypothyroidism and adrenal insufficiency are occasionally noted. Skin changes are diverse: hyperpigmentation, hypertrichosis, skin thickening, and digital club­ bing. Other manifestations include peripheral edema, ascites, pleural effusions, fever, and thrombocytosis. Not all the components of POEMS syndrome may be present initially. The pathogenesis of the disease is unclear, but high circulating levels of the proinflammatory cytokines IL-1, IL-6, VEGF, and TNF have been documented, and levels of the inhibitory cytokine transforming growth factor β are lower than expected. Treatment of the myeloma may result in an improvement in the other disease manifestations. Patients are often treated similarly to those with myeloma. Plas­ mapheresis does not appear to be of benefit in POEMS syndrome. Patients presenting with isolated sclerotic lesions may have resolution of neuropathic symptoms after local therapy for plasmacytoma with radiotherapy. Similar to MM, novel agents and HDT with autologous stem cell transplantation have been pursued in selected patients and have been associated with prolonged progression-free survival. HEAVY CHAIN DISEASES The heavy chain diseases are rare lymphoplasmacytic malignan­ cies. Their clinical manifestations vary with the heavy chain isotype. Patients have absence of light chain and secrete a defective heavy chain that usually has an intact Fc fragment and a deletion in the Fd region. Gamma, alpha, and mu heavy chain diseases have been described, but no reports of delta or epsilon heavy chain diseases have appeared. Molecular biologic analysis of these tumors has revealed structural genetic defects that may account for the aberrant chain secreted. ■ ■GAMMA HEAVY CHAIN DISEASE (FRANKLIN’S DISEASE) This disease affects individuals of widely different age groups and countries of origin. It is characterized by lymphadenopathy, fever, anemia, malaise, hepatosplenomegaly, and weakness. It is frequently associated with autoimmune diseases, especially rheumatoid arthritis. Its most distinctive symptom is palatal edema, resulting from involve­ ment of nodes in Waldeyer’s ring, and this may progress to produce respiratory compromise. The diagnosis depends on the demonstra­ tion of an anomalous serum M component (often <20 g/L [<2 g/dL]) that reacts with anti-IgG but not anti–light chain reagents. The M component is typically present in both serum and urine. Most of the paraproteins have been of the γ1 subclass, but other subclasses have been seen. The patients may have thrombocytopenia, eosinophilia, and nondiagnostic bone marrow that may show increased numbers of lymphocytes or plasma cells that do not stain for light chain. Patients usually have a rapid downhill course and die of infection; however, some patients have survived 5 years with chemotherapy. Therapy is indicated when symptomatic and involves chemotherapeutic combina­ tions used in low-grade lymphoma. Rituximab has also been reported to show efficacy. ■ ■ALPHA HEAVY CHAIN DISEASE (SELIGMANN’S DISEASE) This is the most common of the heavy chain diseases. It is closely related to a malignancy known as Mediterranean lymphoma, a dis­ ease that affects young persons in parts of the world where intestinal parasites are common, such as the Mediterranean, Asia, and South America. The disease is characterized by an infiltration of the lamina propria of the small intestine with lymphoplasmacytoid cells that secrete truncated alpha chains. Demonstrating alpha heavy chains is difficult because the alpha chains tend to polymerize and appear as a smear instead of a sharp peak on electrophoretic profiles. Despite the polymerization, hyperviscosity is not a common problem in alpha heavy chain disease. Without J chain–facilitated dimerization, viscos­ ity does not increase dramatically. Light chains are absent from serum and urine. The patients present with chronic diarrhea, weight loss, and malabsorption and have extensive mesenteric and paraaortic adenopa­ thy. Respiratory tract involvement occurs rarely. Patients may vary widely in their clinical course. Some may develop diffuse aggressive histologies of malignant lymphoma. Chemotherapy may produce longterm remissions. Rare patients appear to have responded to antibiotic therapy, raising the question of the etiologic role of antigenic stimula­ tion, perhaps by some chronic intestinal infection. Chemotherapy plus antibiotics may be more effective than chemotherapy alone. IPSID is recognized as an infectious pathogen–associated human lymphoma associated with Campylobacter jejuni. It involves mainly the proximal small intestine, resulting in malabsorption, diarrhea, and abdominal pain. IPSID is associated with excessive plasma cell differentiation and produces truncated alpha heavy chain proteins lacking the light chains as well as the first constant domain. Early-stage IPSID responds to antibiotics (30–70% complete remission). Most untreated IPSID patients progress to lymphoplasmacytic and immunoblastic lym­ phoma. Patients not responding to antibiotic therapy are considered for treatment with combination chemotherapy used to treat low-grade lymphoma. ■ ■MU HEAVY CHAIN DISEASE The secretion of isolated mu heavy chains into the serum appears to occur in a very rare subset of patients with CLL. The only features that may distinguish patients with mu heavy chain disease are the presence of vacuoles in the malignant lymphocytes and the excretion of kappa light chains in the urine. The diagnosis requires ultracentrifugation or gel filtration to confirm the nonreactivity of the paraprotein with the light chain reagents because some intact macroglobulins fail to interact with these serums. The tumor cells seem to have a defect in # 47 - 117 Amyloidosis ### 117 Amyloidosis the assembly of light and heavy chains because they appear to contain both in their cytoplasm. Such patients are not treated differently from other patients with CLL (Chap. 107). ■ ■FURTHER READING Corre J et al: Risk factors in multiple myeloma: is it time for a revision? Blood 137:16, 2021. Hideshima T, Anderson KC: Signaling pathway mediating myeloma cell growth and survival. Cancers (Basel) 13:216, 2021. Hillengass J et al: International myeloma working group consensus recommendations on imaging in monoclonal plasma cell disorders. Lancet Oncol 20:e302, 2019. Kumar S et al: International Myeloma Working Group consensus crite­ ria for response and minimal residual disease assessment in multiple myeloma. Lancet Oncol 17:e328, 2016. Moreau P et al: Treatment of relapsed and refractory multiple myeloma: Recommendations from the International Myeloma Work­ ing Group. Lancet Oncol 22:e105, 2021. Munshi NC et al: A large meta-analysis establishes the role of MRD negativity in long-term survival outcomes in patients with multiple myeloma. Blood Adv 4:5988, 2020. Raje NS et al: Consensus guidelines and recommendations for infec­ tion prevention in multiple myeloma: A report from the International Myeloma Working Group. Lancet Haematol 9:e143 2022. Rajkumar SV et al: International Myeloma Working Group updated criteria for the diagnosis of multiple myeloma. Lancet Oncol 15:e538, 2014. Richardson PG et al: Triplet therapy, transplantation, and mainte­ nance until progression in myeloma. N Engl J Med 387:132, 2022. Robiou du Pont S et al: Genomics of multiple myeloma. J Clin Oncol 35:963, 2017. Terpos E et al: Treatment of multiple myeloma-related bone disease: Recommendations from the Bone Working Group of the Interna­ tional Myeloma Working Group. Lancet Oncol 22:e119, 2021. Treon SP et al: How I use genomics and BTK inhibitors in the treat­ ment of Waldenstrom macroglobulinemia. Blood 143:1702, 2024. John L. Berk, Vaishali Sanchorawala Amyloidosis ■ ■GENERAL PRINCIPLES Amyloidosis is the term for a group of protein misfolding disorders characterized by the extracellular deposition of insoluble polymeric protein fibrils in tissues and organs. A robust cellular machinery exists to chaperone proteins during the process of synthesis and secretion, to ensure that they achieve correct tertiary conformation and function, and to eliminate proteins that misfold. However, genetic mutation, incorrect processing, and other factors may favor misfolding, with consequent loss of normal protein function and intracellular or extra­ cellular aggregation. Many diseases, ranging from cystic fibrosis to Alzheimer’s disease, are now known to involve protein misfolding. In the amyloidoses, the aggregates are typically extracellular, and the misfolded protein subunits assume a common antiparallel, β-pleated sheet–rich structural conformation that leads to the formation of higher-order oligomers and then fibrils with unique staining proper­ ties. The term amyloid was coined around 1854 by the pathologist Rudolf Virchow, who thought that these deposits resembled starch (Latin amylum) under the microscope. Amyloid diseases, defined by the biochemical nature of the protein composing the fibril deposits, are classified according to whether they are systemic or localized, whether they are acquired or inherited, and their clinical patterns (Table 117-1). The standard nomenclature is AX, where A indicates amyloidosis and X represents the protein pres­ ent in the fibril. This chapter focuses primarily on the systemic forms. AL amyloidosis refers to amyloid composed of immunoglobulin light chains; this disorder, formerly termed primary systemic amyloidosis, arises from a clonal B-cell or plasma cell disorder and can be associated with myeloma or lymphoma. ATTR amyloidosis, the most prevalent of the familial amyloidoses, refers to amyloid derived from wild-type or mutated transthyretin (TTR), the transport protein for thyroid hormone and retinol-binding protein. AA amyloid is composed of the acute-phase reactant protein serum amyloid A (SAA) and occurs in the setting of chronic inflammatory or infectious diseases; for this reason, this type was formerly known as secondary amyloidosis. Aβ2M amyloid results from misfolded β2-microglobulin, occurring in individuals with long-standing renal disease who have undergone dialysis, typically for years. Aβ, the most common form of localized amyloidosis, is found in the brain of patients with Alzheimer’s disease after abnormal pro­ teolytic processing and aggregation of polypeptides derived from the amyloid precursor protein. Diagnosis and treatment of the amyloidoses rest upon the histopath­ ologic identification of amyloid deposits and immunohistochemical, biochemical, or genetic determination of amyloid type (Fig. 117-1). In the systemic amyloidoses, the clinically involved organs can be biopsied, but amyloid deposits may be found in any tissue of the body. Historically, blood vessels of the gingiva or rectal mucosa were often examined, but the most easily accessible tissue—positive in more than 80% of patients with systemic amyloidosis—is abdominal fat. After local anesthesia, fat is aspirated with a 16-gauge needle from the subcu­ taneous layer of the abdominal wall. Fat globules expelled onto a glass slide can be stained for amyloid by Congo red dye, thus avoiding a sur­ gical procedure. If this material is negative, more invasive biopsies of the involved organ like kidney, heart, liver, tongue, or gastrointestinal tract can be considered in patients in whom amyloidosis is suspected. The regular β-sheet structure of amyloid deposits exhibits a unique “green” birefringence by polarized light microscopy when stained with Congo red dye; other regular protein structures (e.g., collagen) appear white under these conditions. The 10-nm-diameter fibrils can also be visualized by electron microscopy of paraformaldehyde-fixed tissue. Once amyloid is found, the precursor protein type must be determined by immunohistochemistry, immunoelectron microscopy, or extraction and biochemical analysis employing mass spectrometry; gene sequenc­ ing is used to identify mutants causing hereditary amyloidosis. How­ ever, a mass spectrometry–based analysis of the amyloid-containing tissues is now considered the best approach, with a reported sensitivity of 88% and specificity of 96%, which are higher than immunochemical techniques, and this technique does not require a large panel of antisera to identify non-AL amyloidosis. The patient’s history, physical find­ ings, and clinical presentation, including age and ethnic origin, organ system involvement, underlying diseases, and family history, may pro­ vide helpful clues as to the type of amyloidosis. However, there can be considerable overlap in clinical presentations, and accurate typing of the amyloidogenic protein is essential to guide appropriate therapy and offer genetic counseling as appropriate. CHAPTER 117 Amyloidosis The mechanisms of fibril formation and tissue toxicity remain con­ troversial. The “amyloid hypothesis,” as it is currently understood, pro­ poses that precursor proteins undergo a process of reversible unfolding or misfolding; misfolded proteins form oligomeric aggregates, higherorder polymers, and then fibrils that deposit in tissues. Accumulating evidence suggests that the oligomeric intermediates may constitute the most toxic species. Oligomers are more capable than fibrils of interact­ ing with cells and inducing formation of reactive oxygen species and stress signaling. Ultimately, the fibrillar tissue deposits are likely to interfere with normal organ function. However, direct proteotoxicity of the soluble oligomers also can lead to organ dysfunction. A more sophisticated understanding of the mechanisms leading to amyloid formation and cell and tissue dysfunction will continue to provide new targets for therapies. The clinical syndromes of the amyloidoses are associated with rela­ tively nonspecific alterations in routine laboratory tests. Blood counts are usually normal, although the erythrocyte sedimentation rate is TABLE 117-1  Amyloid Precursor Proteins and Their Clinical Syndromes DESIGNATION PRECURSOR CLINICAL SYNDROME CLINICAL INVOLVEMENT Systemic Amyloidoses     AL Immunoglobulin light chain Primary or myeloma-associateda Any AH Immunoglobulin heavy chain Rare variant of primary or myeloma-associated Any AA Serum amyloid A protein Secondary; reactiveb Renal, heart, other Aβ2M β2-Microglobulin Hemodialysis-associated Synovial tissue, bone ATTR Transthyretin Familial (mutant) Age-related (wild type) AApoAI Apolipoprotein AI Familial Hepatic, renal AApoAII Apolipoprotein AII Familial Renal Agel Gelsolin Familial Cornea, cranial nerves, skin, renal AFib Fibrinogen Aa Familial Renal, vascular ALys Lysozyme Familial Renal, hepatic ALECT2 Leukocyte chemotactic factor 2 Undefined Renal Localized Amyloidoses     Aβ Amyloid β protein Alzheimer’s disease; Down’s syndrome Central nervous system ACys Cystatin C Cerebral amyloid angiopathy Central nervous system, vascular APrP Prion protein Spongiform encephalopathies Central nervous system AIAPP Islet amyloid polypeptide (amylin) Diabetes-associated Pancreas PART 4 Oncology and Hematology Acal Calcitonin Medullary carcinoma of the thyroid Thyroid AANF Atrial natriuretic factor Atrial fibrillation Cardiac atria APro Prolactin Endocrinopathy Pituitary ASgl Semenogelin I Age-related; incidental autopsy or biopsy finding Seminal vesicles aLocalized AL deposits can occur in skin, conjunctiva, urinary bladder, and the tracheobronchial tree. bSecondary to chronic inflammation or infection or to a hereditary periodic fever syndrome such as familial Mediterranean fever. CLINICAL SUSPICION OF AMYLOIDOSIS Noninvasive Tissue Biopsy (Congo red staining of abdominal fat or other tissue) + – Invasive Tissue Biopsy (Congo red staining of affected major organs) + – No further work-up Identify Diagnosis Mass spectrometry or IHC of amyloid deposits Kappa or lambda light chain AL amyloidosis (Screen for cardiac, renal, hepatic, autonomic involvement, and factor X deficiency) Monoclonal protein in serum or urine Plasma cell dyscrasia in bone marrow Amyloid A protein Underlying chronic inflammatory disease AA amyloidosis (Screen for renal, hepatic involvement) Transthyretin Mutant transthyretin +/– family history ATTRm familial amyloidosis (Screen for neuropathy, cardiomyopathy; screen relatives) Wild-type transthyretin (usually males >65, cardiac) ATTRwt or age-related amyloidosis Negative Mutant ApoAI, ApoAII, fibrinogen, lysozyme, gelsolin Familial amyloidosis of rare type (Screen for renal, hepatic, GI involvement) FIGURE 117-1  Algorithm for the diagnosis of amyloidosis and determination of type. Clinical suspicion: unexplained nephropathy, cardiomyopathy, neuropathy, enteropathy, arthropathy, and macroglossia. ApoAI, apolipoprotein AI; ApoAII, apolipoprotein AII; GI, gastrointestinal; IHC, immunohistochemistry. Cardiac, peripheral and autonomic nerves, soft tissues, spine, bladder frequently elevated. Patients with glomerular kidney involvement generally have proteinuria, often in the nephrotic range, leading to hypo­ albuminemia that may be severe; patients with serum albumin levels <2 g/dL generally have pedal edema or anasarca. Amyloid cardiomy­ opathy is characterized by concentric ventricular hypertrophy and diastolic dysfunction associated with elevation of brain natriuretic peptide (BNP) or N-terminal pro–brain natriuretic peptide (NT-proBNP) as well as troponin. These car­ diac biomarkers can be used for disease staging, prognostication, and disease activity monitoring in patients with AL amyloidosis. Notably, renal insufficiency can falsely elevate levels of these bio­ markers. Biomarkers of cardiac remodeling— that is, matrix metalloproteinases and tissue inhibitors of metalloproteinases—are altered in the serum of patients with amyloid cardiomy­ opathy. Electrocardiographic and echocardio­ graphic features of amyloid cardiomyopathy are described below. Patients with liver involvement, even when advanced, usually develop cholestasis with an elevated alkaline phosphatase concentra­ tion with minimal alteration of the aminotrans­ ferases and preservation of synthetic function. In AL amyloidosis, endocrine organs may be involved, and hypothyroidism, hypoadrenalism, or even hypopituitarism can occur. Although none of these findings is specific for amyloidosis, the presence of abnormalities in multiple organ systems should raise suspicions of the diagnosis. ■ ■AL AMYLOIDOSIS Etiology and Incidence  AL amyloidosis is most frequently caused by a clonal expansion of bone marrow plasma cells that secrete a monoclonal immunoglobulin light chains forming amyloid fibrils and deposits in tissues. Whether the clonal plasma cells produce a light chain that misfolds and leads to AL amyloidosis or a light chain that folds properly, allowing the cells to inexorably expand over time and develop into multiple myeloma (Chap. 116), may depend upon primary sequence of the clonal light chain or other genetic or epigenetic factors. AL amyloidosis can occur with multiple myeloma or other B lymphoproliferative diseases, includ­ ing non-Hodgkin’s lymphoma (Chap. 113) and Waldenström’s macro­ globulinemia (Chap. 116). AL amyloidosis is the most common type of systemic amyloidosis diagnosed in North America. Its incidence has been estimated at 8–12 cases per 100,000 population; however, ascer­ tainment continues to be inadequate, and the true incidence may be much higher. AL amyloidosis, like other plasma cell disorders, usually occurs after age 40 and is often progressive and fatal if untreated. Pathology and Clinical Features  Amyloid deposits are usually widespread in AL amyloidosis and can be present in the interstitium of any organ outside the central nervous system. The amyloid fibril deposits are composed of full-length 23-kDa monoclonal immuno­ globulin light chains as well as fragments. Accessory molecules codeposited with light chain fibrils (as well as with other amyloid fibrils) include serum amyloid P component, apolipoproteins e and A-IV, glycosaminoglycans, and metal ions. Although all kappa and lambda light chain subtypes have been identified in AL amyloid fibrils, lambda subtypes predominate. AL amyloidosis is often a rapidly progressive disease that presents as a pleiotropic set of clinical syndromes, recognition of which is key for initiation of the appropriate workup. Nonspecific symptoms of fatigue and weight loss are common; however, the diagnosis is rarely considered until symptoms referable to a specific organ develop. The kidneys are a frequently involved organ and are affected in 60–70% of patients. Renal amyloidosis usually manifests as proteinuria, often in the nephrotic range and associated with hypoalbuminemia, second­ ary hypercholesterolemia and hypertriglyceridemia, and edema or anasarca. In some patients, interstitial rather than glomerular amyloid deposition can produce azotemia without proteinuria. The heart is the other commonly affected organ (70–80% of patients), and cardiac involvement is the leading cause of death from AL amyloidosis. Early on, the electrocardiogram may show low voltage in the limb leads with a pseudo-infarct pattern. Echocardiographic features of disease include concentrically thickened ventricles and diastolic dysfunction with an abnormal global longitudinal strain pattern; a “sparkly” appearance has been described but is often not seen with modern high-resolution echocardiographic techniques. Poor atrial contractility occurs even in sinus rhythm, and patients with cardiac amyloidosis are at risk for development of atrial thrombi and thromboembolic complications. Cardiac magnetic resonance imaging (MRI) can show increased wall thickness and characteristic delayed gadolinium enhancement of the subendocardium. Nervous system symptoms include peripheral sen­ sorimotor neuropathy and/or autonomic dysfunction manifesting as gastrointestinal motility disturbances (early satiety, diarrhea, constipa­ tion), dry eyes and mouth, impotence, orthostatic hypotension, and/ or neurogenic bladder. Macroglossia (Fig. 117-2A), a pathognomonic sign of AL amyloidosis, is seen in only ~10% of patients. Liver involve­ ment causes cholestasis and hepatomegaly. The spleen is frequently involved, and there may be functional hyposplenism in the absence of significant splenomegaly. Many patients experience “easy bruising” due to amyloid deposits in capillaries or deficiency of clotting factor X due to binding to amyloid fibrils; cutaneous ecchymoses appear, particularly around the eyes, producing another uncommon but pathognomonic finding, the “raccoon-eye” sign (Fig. 117-2B). Other findings include nail dystrophy (Fig. 117-2C), alopecia, and amyloid arthropathy with thickening of synovial membranes in the wrists and shoulders. The presence of a multisystemic illness or general fatigue along with any of these clinical syndromes should prompt a workup for amyloidosis. Diagnosis  Identification of an underlying clonal plasma cell or B lymphoproliferative process and a clonal light chain are key to the A CHAPTER 117 B Amyloidosis C FIGURE 117-2  Clinical signs of AL amyloidosis. A. Macroglossia. B. Periorbital ecchymoses. C. Fingernail dystrophy. diagnosis of AL amyloidosis. Serum protein electrophoresis and urine protein electrophoresis, although of value in multiple myeloma, are not useful screening tests if AL amyloidosis is suspected because the clonal light chain or whole immunoglobulin often is not present in sufficient amounts to produce a monoclonal “M-spike” in the serum or light chain (Bence Jones) protein in the urine. However, more than 90% of patients with AL amyloidosis have serum or urine monoclonal light chain or whole immunoglobulin detectable by immunofixation electrophoresis of serum (SIFE) or urine (UIFE) (Fig. 117-3A) or by nephelometric measurement of serum “free” light chains (i.e., light chains circulating in monomeric form rather than in an immuno­ globulin tetramer with heavy chain). Examining the ratio as well as the absolute amount of serum-free light chains is essential, as renal insuf­ ficiency reduces light chain clearance, nonspecifically elevating both isotypes. In addition, an increased percentage of plasma cells in the bone marrow—typically 5–30% of nucleated cells—is found in ~90% of patients. Kappa or lambda clonality should be demonstrated by flow cytometry, immunohistochemistry, or in situ hybridization for light chain mRNA (Fig. 117-3B). More sensitive mass spectrometry–based assays can have higher levels of detection for low concentration of monoclonal protein. A monoclonal serum protein by itself is not diagnostic of amy­ loidosis, since monoclonal gammopathy of uncertain significance is common in older patients (Chap. 116). However, when monoclonal gammopathy of uncertain significance is found in patients with biopsyproven amyloidosis, the AL type should be ruled out. Similarly, patients thought to have “smoldering myeloma” because of a modest elevation of bone-marrow plasma cells should be screened for AL amyloidosis if A PART 4 Oncology and Hematology B FIGURE 117-3  Laboratory features of AL amyloidosis. A. Serum immunofixation electrophoresis reveals an IgGκ monoclonal protein in this example; serum protein electrophoresis is often normal. B. Bone marrow biopsy sections stained by immunohistochemistry with antibody to CD138 (syndecan, highly expressed on plasma cells) (left) or by in situ hybridization with fluorescein-tagged probes (Ventana Medical Systems) binding to κ mRNA (center) and λ mRNA (right) in plasma cells. (Photomicrograph courtesy of C. O’Hara; with permission.) they have signs or symptoms of renal, cardiac, or neurologic disease. Accurate tissue amyloid typing is essential for appropriate treatment. Immunohistochemical staining of the amyloid deposits is useful if they selectively bind one light chain antibody in preference to the other; some AL deposits bind antibodies nonspecifically. Commercial antibodies used for immunohistochemistry may not be accurate in amyloid typing. Immunoelectron microscopy is more reliable; laser capture microdissection and tandem mass spectrometry–based typing of the amyloid precursor protein have become the diagnostic standard. In ambiguous cases, other forms of amyloidosis should be thoroughly excluded with appropriate genetic and other testing. Staging System and Risk Stratification  The current staging systems for systemic AL amyloidosis are based on the biomarkers of plasma cell dyscrasia and cardiac and renal involvement. The Mayo 2004 staging system is based on the levels of NT-proBNP and cardiac troponins and was modified by European investigators to identify and classify very-high-risk patients. This cardiac staging system is the most widely used to determine patient management. This staging system was modified (Mayo 2012) to include clonal burden, assessed by dFLC (difference between involved and uninvolved circulating free light chain) concentration, which has independent ability to predict survival. Boston University investigators introduced a staging system incorporating BNP and troponin I that also is able to predict survival. Patients with AL amyloidosis with a very low (<50 mg/L) dFLC level have a significantly better outcome irrespective of cardiac stage. A renal staging system based on 24-h urine protein excretion and esti­ mated glomerular filtration rate (eGFR) predicting the progression to dialysis at 2 years has also been developed and validated. Several other biomarkers have been shown to predict outcomes and survival but have not been incorporated in staging systems yet. TREATMENT AL Amyloidosis Extensive multisystemic involvement typifies AL amyloidosis, and historically, the median survival without treatment was usually only ~1–2 years from the time of diagnosis. Marked progress in the outcome and survival has taken place over the past four decades with advent of new therapies, increased awareness, and accurate diagnosis. Current therapies target the clonal bone marrow plasma cells, using approaches employed for multiple myeloma. High-dose intravenous (IV) melphalan followed by autologous stem cell trans­ plantation (HDM/SCT) produces complete hematologic responses in ~40% of treated patients, as determined by loss of clonal plasma cells in the bone marrow and disappearance of the amyloidogenic monoclonal light chain, as determined by SIFE/UIFE and free light chain quantitation. Six to 12 months after achieving a hematologic response, improvements in organ function and quality of life may occur. Hematologic responses appear to be more durable after HDM/SCT than in multiple myeloma, with remissions continuing in some patients beyond 15 years without additional treatment. Unfortunately, only ~20–30% of all AL amyloidosis patients are suitable for aggressive treatment, and even at specialized treat­ ment centers, transplantation-related morbidity and mortality rates are higher than those for other hematologic diseases because of impaired organ function at initial presentation. Amyloid cardiomy­ opathy, poor nutritional and performance status, and multiorgan disease contribute to excess morbidity and mortality. A bleeding diathesis resulting from adsorption of clotting factor X to amy­ loid fibrils also increases mortality rates; however, this syndrome occurs in only 5–10% of patients. A randomized multicenter trial conducted in France compared oral melphalan and dexamethasone with HDM/SCT and failed to show a benefit of dose-intensive treat­ ment, although the transplantation-related mortality rate in this study was very high. It has become clear that careful selection of patients and expert peritransplantation management are essential in reducing transplantation-related complications. The best therapy for those who are not eligible to receive SCT is based on a U.S. Food and Drug Administration–approved therapy of CyBorD (cyclophosphamide, bortezomib [a protea­ some inhibitor], and dexamethasone) with daratumumab. Patient characteristics should be considered when choosing a regimen; for example, treatment with bortezomib plus oral melphalan and dexa­ methasone (MDex) can overcome the effects of both gain of 1q21 (which confers a poorer outcome with oral melphalan) and t(11;14) (which confers a poorer outcome with bortezomib). Transplantineligible patients in whom bortezomib is contraindicated due to preexisting peripheral neuropathy can be treated with MDex or combinations based on immunomodulatory drugs (e.g., lenalido­ mide or pomalidomide). High-risk patients represent ~15–20% of all individuals with AL amyloidosis and are a challenge owing to advanced cardiac stage (IIIb) or severe heart failure (New York Heart Association class III or IV) as they are excluded from most of the clinical trials. Novel antifibril monoclonal antibodies are currently undergoing clinical trials in combination with treatments directed against the plasma cell dyscrasia (CyBorD plus daratumumab [anti-CD38]) in patients with newly diagnosed AL amyloidosis. Clinical trials are essential in improving therapy for this rare disease. Supportive care is important for patients with any type of amy­ loidosis. For nephrotic syndrome, diuretics and support stockings can ameliorate edema; angiotensin-converting enzyme inhibitors should be used with caution and have not been shown to slow renal disease progression. Effective diuresis can be facilitated with albumin infusions to raise intravascular oncotic pressure. Conges­ tive heart failure due to amyloid cardiomyopathy is best treated with diuretics; it is important to note that digitalis, calcium channel blockers, and beta blockers are relatively contraindicated as they can interact with amyloid fibrils and produce heart block and wors­ ening heart failure. Amiodarone has been used for atrial and ven­ tricular arrhythmias. Automatic implantable defibrillators appear to have reduced effectiveness due to the thickened myocardium, but they may benefit some patients. Atrial ablation is an effective approach for atrial fibrillation. For conduction abnormalities, ven­ tricular pacing may be indicated. Atrial contractile dysfunction is common in amyloid cardiomyopathy and associated with increased thromboembolic complications, prompting considerations of anti­ coagulation even in the absence of atrial fibrillation. Autonomic neuropathy can be treated with α agonists such as midodrine to support postural blood pressure; gastrointestinal dysfunction may respond to motility or bulk agents. Nutritional supplementation, either oral or parenteral, is also important. In localized AL amyloidosis, amyloid deposits can be produced by clonal plasma cells infiltrating local sites in the airways, bladder, skin, or lymph nodes (Table 117-1). These deposits may respond to surgical intervention or elimination of the responsible plasma cell clone by low-dose radiation therapy (typically only 20 Gy); systemic treatment generally is not appropriate. Patients should be referred to a center familiar with management of these rare manifestations of amyloidosis. ■ ■AA AMYLOIDOSIS Etiology and Incidence  AA amyloidosis can occur in association with almost any chronic inflammatory state (e.g., rheumatoid arthritis, inflammatory bowel disease, ankylosing spondylitis, familial Medi­ terranean fever [Chap. 381], or other periodic fever syndromes) or chronic infections such as tuberculosis, osteomyelitis, or subacute bac­ terial endocarditis. In the United States and Europe, AA amyloidosis has become less common, occurring in fewer than 2% of patients with these diseases, presumably because of advances in anti-inflammatory and antimicrobial therapies. It has also been described in associa­ tion with Castleman’s disease, lymphomas, and renal cell carcinoma, emphasizing the diagnostic importance of computed tomography (CT) scanning to look for such tumors as well as serologic and microbiologic studies. In up to 20% of patients, AA amyloidosis can also be seen with­ out any identifiable underlying disease. Pathology and Clinical Features  Organ involvement in AA amyloidosis usually begins in the kidneys. Hepatomegaly, splenomeg­ aly, and autonomic neuropathy can also occur as the disease progresses; cardiomyopathy is a late manifestation in ~10–25% of patients. The symptoms and signs of AA disease cannot be reliably distinguished from those of AL amyloidosis. AA amyloid fibrils are usually composed of an 8-kDa, 76-amino-acid N-terminal portion of the 12-kDa precur­ sor protein SAA. This acute-phase protein is synthesized in the liver and transported by high-density lipoprotein (HDL3) in the plasma. Several years of an underlying inflammatory disease causing chronic elevation of SAA levels usually precede fibril formation, although infections can lead to AA amyloid deposition more rapidly. TREATMENT AA Amyloidosis Primary therapy for AA amyloidosis consists of treatment of the underlying inflammatory or infectious disease. Treatment that sup­ presses or eliminates the inflammatory state or infection decreases the circulating levels of SAA, slowing the rate of amyloid fibril formation. For familial Mediterranean fever, colchicine at a dose of 1.2–1.8 mg/d is the standard treatment. However, colchicine has not been helpful for AA amyloidosis of other causes or for other amyloidoses. Tumor necrosis factor and interleukin 1 and inter­ leukin 6 antagonists can effectively interrupt cytokine signaling that drives many inflammatory syndromes, inhibiting hepatic SAA production and limiting AA amyloid deposition. Development of a fibril-specific agent (eprodisate) that interferes with the interaction of serum amyloid A protein and glycosaminoglycans to prevent or disrupt fibril formation failed in phase 3 trials. ■ ■ATTR AND OTHER HEREDITARY AMYLOIDOSES The familial amyloidoses are autosomal dominant diseases in which mutated or variant plasma proteins misfold or aggregate to form betasheet rich amyloid deposits. These diseases are rare, with an estimated case incidence of <1/100,000 population in the United States, although founder effects in remote areas of Portugal, Sweden, and Japan pro­ duce a higher local prevalence of disease. The most prevalent form of hereditary amyloidosis arises from mutation of the abundant liverderived plasma protein transthyretin (TTR, also known as prealbumin) and is termed ATTR variant (ATTRv) amyloid. More than 130 TTR mutations typically conferring one-amino-acid substitutions have been described, with most inducing clinical ATTR amyloid disease. Toxic TTR oligomers and ATTR amyloid deposits target peripheral and auto­ nomic nervous systems and the heart. One TTR variant, V122I, occurs in nearly 4% of the African-American and Afro-Caribbean populations and is associated with late-onset cardiac amyloidosis. The actual inci­ dence and penetrance of disease in the African-American population are the subject of ongoing research, but consideration of V122I ATTR amyloidosis is warranted in African-American patients who present with concentric cardiac hypertrophy and evidence of diastolic heart failure, particularly in the absence of a history of hypertension or valvular disease. Other familial amyloidoses, caused by variant apoli­ poproteins AI or AII, gelsolin, fibrinogen Aα, or lysozyme, are reported with lower prevalence worldwide. New amyloidogenic serum proteins continue to be identified periodically, including leukocyte chemotactic factor LECT2, which is a cause of renal amyloidosis in Hispanic and Pakistani populations. Although the clustering of ALECT2 cases sug­ gests heritability, no LECT2 gene-coding sequence variations have been identified. CHAPTER 117 Amyloidosis Normal (wild-type) transthyretin can also misfold and aggregate to form ATTR amyloid, principally expressed in men beginning in the seventh decade with increasing prevalence with age. Formerly termed senile systemic amyloidosis, ATTRwt amyloid is reported at autopsy in 25% of hearts from male patients who are 80 years and older. Although it is unclear why a wild-type protein becomes amyloidogenic, aging inefficiencies of intracellular quality-assurance mechanisms (termed the unfolded protein response) likely predispose to secretion of pro­ teins prone to misaggregation. Due to the numbers of aging men globally, ATTRwt is the most prevalent and rapidly growing form of amyloidosis in the world today. Data to date characterize ATTRwt amyloidosis as a disease of aging, not inheritance. Clinical Features and Diagnosis  ATTRv amyloidosis has varied presentations predicted by the specific TTR mutation. Consequently, kindreds typically express similar disease timing and clinical course. Apparent sporadic presentations (no recognized family history) often reflect incomplete penetrance of the TTR mutation and not a sponta­ neous event. ATTRv amyloidosis presents as familial amyloidotic poly­ neuropathy (nerve damage) or familial amyloidotic cardiomyopathy (heart damage), although the majority of cases exhibit multiorgan dis­ ease. Peripheral neuropathy begins as a length-dependent small-fiber sensorimotor neuropathy first exhibited in the feet with ascending progression to the upper extremities. Autonomic neuropathy manifests as smooth muscle dysmotility (dysphagia, diarrhea, urinary retention), vascular dysregulation (orthostatic hypotension, erectile dysfunction), and anhidrosis. Soft tissue disease (carpal tunnel syndrome, tendi­ nopathy, and spinal stenosis) commonly precedes nerve or heart mani­ festations of disease by one to two decades, particularly in ATTRwt amyloid patients who frequently report bicipital, patellar, or Achilles tendon rupture. Less common expressions of ATTRv include vitreous opacities and leptomeningeal amyloid deposition from variant protein produced by the retinal epithelium and choroid plexus, respectively. ATTR amyloid involvement of the heart is clinically better tolerated than AL amyloid cardiomyopathy as reflected by both the time from heart failure presentation to death in untreated cases of ATTR (median 42–48 months) versus AL (median 6 months) amyloidosis, and the dramatically greater burden of disease by echocardiographic measures at symptomatic presentation. Typical syndromes associated with non-ATTR forms of hereditary (AF) disease include renal amyloidosis with mutant fibrinogen, lyso­ zyme, or apolipoproteins; hepatic amyloidosis with apolipoprotein AI; and amyloidosis of cranial neuropathy with corneal lattice dystrophy pathognomonic of gelsolin (Finnish) amyloidosis. Patients with AF amyloidosis can present with clinical syndromes that mimic those of patients with AL disease. Rarely, AF carriers can develop AL disease or AF patients may have monoclonal gammopathy without AL. Thus, it is important to screen for plasma cell disorders and for protein muta­ tions in patients with amyloidosis. Although mass spectrometry often detects amino acid sequence variations, it is not designed to definitively identify specific protein variations; DNA sequencing is the diagnostic standard for AF mutations. TREATMENT ATTR Amyloidosis PART 4 Oncology and Hematology Untreated, survival after onset of ATTR disease is 4–15 years depending on whether the disease affects primarily the heart or nervous system, respectively. To date, therapeutic strategies used to control ATTR amyloidosis include: (1) orthotopic liver trans­ plantation (OLT) to replace the factory of the mutated protein (only applicable to ATTRv); (2) stabilization of circulating TTR tetramers, preventing TTR monomer release and amyloid fibril formation; and (3) TTR gene silencing (RNA interference or anti­ sense oligonucleotide agents), suppressing hepatic TTR production and subsequent ATTR fibril formation. After nearly 30 years as the principal treatment, OLT is now rarely employed, limited to patients with ATTRv amyloid, early peripheral neuropathy (V30M ATTR), and minimal systemic amyloid burden. Patients with more extensive amyloid (late V30M and non-V30M TTR mutations) who undergo OLT often suffer posttransplant disease progression due to allograft wild-type ATTR complexing on preexisting amy­ loid deposits. The TTR small-molecule thyroxine mimetic agents, diflunisal and tafamidis, bind to the kinetically stable tetrameric TTR conformation, limiting release and misfolding of monomeric protein, which is the critical step in TTR amyloidogenesis. Inter­ national phase 3 randomized controlled trials demonstrate that TTR stabilizers slow but infrequently stop progression of ATTR polyneuropathy (diflunisal) and cardiomyopathy (tafamidis). TTR gene silencers (patisiran, inotersen, vutrisiran, eplontersen) more reliably halt neurologic disease progression by minimizing produc­ tion of the amyloidogenic protein by the liver. Indeed, 35–60% of treated patients with familial amyloid polyneuropathy exhibit improved sensory nerve deficits, a novel finding. Therapeutic drug trials are underway to examine the safety, tolerability, and effective­ ness of TTR gene silencers for ATTR cardiomyopathy. Preliminary data suggest TTR gene silencers may promote heart remodeling and improve systolic function in patients with wild type and variant ATTR amyloid cardiomyopathy. Future clinical trials are set to examine the applicability of (1) one-time CRISPR/cas9 gene editing or (2) ATTR amyloid-depleting antibodies in patients with either ATTR polyneuropathy or cardio­ myopathy. These antibodies are designed to recognize and bind nonnative (misfolded) TTR epitopes, mobilizing macrophages and monocytes to disrupt existing amyloid deposits. Whether disrupt­ ing amyloid deposits renews heart and nerve function will be deter­ mined by the outcome of these pivotal trials. The extraordinary pace of drug development harnessing cuttingedge science in this orphan disease has extended survival and improved quality of life. Ironically, these advances expose pre­ viously unrecognized leptomeningeal (brain) and vitreous (eye) ATTR disease due to their occurrence late in disease, highlighting the unmet need for effective amyloid treatments that penetrate the blood-brain barrier. ■ ■Aa2M AMYLOIDOSIS Aβ2M amyloid is composed of β2-microglobulin, the invariant chain of class I human leukocyte antigens, and produces rheumatologic manifestations in patients undergoing long-term hemodialysis and, rarely, in patients with a hereditary form of disease. β2-Microglobulin is excreted by the kidney, and levels become elevated in end-stage renal disease. The molecular mass of β2M is 11.8 kDa—above the cutoff of some dialysis membranes. The incidence of this disease appears to be declining with the use of newer membranes in high-flow dialysis tech­ niques. Aβ2M amyloidosis usually presents as carpal tunnel syndrome, persistent joint effusions, spondyloarthropathy, or cystic bone lesions. Carpal tunnel syndrome is often the first symptom. In the past, persis­ tent joint effusions accompanied by mild discomfort were found in up to 50% of patients who had undergone dialysis for >12 years. Involve­ ment is bilateral, and large joints (shoulders, knees, wrists, and hips) are most frequently affected. The synovial fluid is noninflammatory, and β2M amyloid can be found if the sediment is stained with Congo red. Although less common, visceral β2M amyloid deposits do occa­ sionally occur in the gastrointestinal tract, heart, tendons, and subcu­ taneous tissues of the buttocks. There are no proven specific therapies for Aβ2M amyloidosis, but cessation of dialysis after renal allografting may lead to symptomatic improvement. SUMMARY A diagnosis of amyloidosis should be considered in patients with unexplained nephropathy, cardiomyopathy (particularly with diastolic dysfunction), neuropathy (either peripheral or autonomic), enter­ opathy, or the pathognomonic soft tissue findings of macroglossia or periorbital ecchymoses. Pathologic identification of amyloid fibrils can be made with Congo red staining of aspirated abdominal fat or of an involved-organ biopsy specimen. Accurate typing by a combination of immunologic, biochemical, and genetic testing is essential in select­ ing appropriate therapy (Fig. 117-1). Systemic amyloidosis should be considered a treatable condition, as anti–plasma cell chemotherapy is highly effective in AL disease and targeted therapies are being developed for AA and ATTR disease. The combination of precursor and end-organ amyloid therapeutics potentially provides not only dis­ ease control but also functional and quality-of-life improvements for patients with amyloidosis. Tertiary referral centers can provide special­ ized diagnostic techniques and access to clinical trials for patients with these rare diseases. ■ ■FURTHER READING Adams D et al: Efficacy and safety of vutrisiran for patients with hereditary transthyretin-mediated amyloidosis with polyneuropathy: A randomized clinical trial. Amyloid 30:1, 2023. Coelho T et al: Eplontersen for hereditary transthyretin amyloidosis with polyneuropathy. JAMA 330:1448, 2023. Griffin JM et al: ATTR amyloidosis: Current and emerging man­ agement strategies: JACC: CardioOncology state-of-the-art review. JACC CardioOncol 3:488, 2021. Gustine JN et al: Predictors of hematologic response and survival with stem cell transplantation in AL amyloidosis: A 25-year longitudinal study. Am J Hematol 97:1189, 2022. Kastritis E et al: Daratumumab-based treatment for immunoglobulin light-chain amyloidosis. N Engl J Med 385:46, 2021. Maurer MS et al: Patisiran treatment in patients with transthyretin cardiac amyloidosis. N Engl J Med 389:1553, 2023. Merlini G et al: Systemic immunoglobulin light chain amyloidosis. Nat Rev Dis Primers 4:38, 2018. Staron A et al: Marked progress in AL amyloidosis survival: A 40-year longitudinal natural history study. Blood Cancer J 11:139, 2021. # 48 - 118 Transfusion Therapy and Biology ### 118 Transfusion Therapy and Biology Pierre Tiberghien, Olivier Garraud, Jacques Chiaroni Transfusion Therapy and Biology Transfusion encompasses the use of blood components (BCs) to pre­ vent or treat anemia, hemorrhage, and bleeding disorders. Occasion­ ally, BCs may be used to treat infection or relapse of malignant blood diseases after allogeneic hematopoietic transplantation. BCs comprise mainly red blood cell concentrates (RBCCs), platelet concentrates (PCs), and plasma for transfusion use as opposed to plasma fraction­ ated into medicinal products (such as immunoglobulin, albumin, and clotting factors). Alongside transfusion safety, ensuring BC quality, assessing in vivo efficacy, and promoting evidence-based transfusion practices are critical aspects of transfusion medicine. Donor medicine does not fall within the scope of this chapter. While particularly safe, blood donations can cause adverse reactions, among which are fainting reactions and iron deficiency. These reac­ tions require preventive approaches and appropriate treatment when needed. BLOOD COMPONENTS BC collection and manufacturing processes are described in Table 118-1. BCs are collected as whole blood or directly as com­ ponents by apheresis. The vast majority of BCs are homologous. Autologous BCs, collected ahead of planned surgery, are now excep­ tional as they present little to no advantage over homologous BCs. Nevertheless, such donation may still be of benefit in the presence of a rare blood group phenotype. All BCs comply with common quality and performance standards and guidelines. Quality assurance encompasses well-defined process­ ing steps and stringent BC quality controls as defined by health author­ ities. Reporting of adverse reactions and events associated with blood collection, BC processing, and transfusion is highly recommended. With the obvious exception of granulocyte concentrates and mono­ nuclear cells, most BCs are now leukocyte-reduced, and universal prestorage leukocyte reduction has been recommended. These BCs contain <1–5.106 donor leukocytes and are associated with reduced incidence of febrile nonhemolytic transfusion reactions (FNHTRs), infections with intracellular pathogens such as cytomegalovirus (CMV), alloimmunization, and immunomodulation. BCs may undergo additional processing steps. These include irra­ diation to prevent graft-versus-host disease (GVHD) in immunosup­ pressed patients, pathogen reduction to further reduce the risk of transfusion-transmitted infections, plasma reduction in patients with severe allergic reactions to BCs, or the manufacturing of specific units for young children, neonates, or intrauterine transfusion. BC constituents undergo centrifugation and filtration and are placed in contact with needles, plastic tubing, and bags, as well as anticoagu­ lants and various additive solutions. BCs are subjected to gas exchanges that are significantly different from aerobic breathing and are main­ tained at temperatures that are not physiologic, such as 22°C or 4°C. Any of these elements may contribute to so-called “storage lesions” and to the presence of bioactive molecules such extracellular vesicles and cell-free mitochondrial DNA in the BC. The clinical impact of such lesions is still under investigation with currently no consensus on this issue. Furthermore, plasma present in BCs contains donor antibodies (Abs). When directed toward antigens (Ags) present in the recipient, such as blood group or tissue (human leukocyte antigen [HLA]) Ags, such Abs may result in adverse events. RBCCs bring only a limited amount of donor plasma (10–30 mL), unlike PCs and obviously plasma. The use of platelet additive solution can replace two-thirds of plasma in PCs, while still leaving the equivalent of one plasma unit of 200 mL per transfused PC. BLOOD GROUP ANTIGENS AND ANTIBODIES Red blood cells (RBCs), as well as other blood constituents such as platelets and neutrophils, express allogeneic determinants. Transfu­ sion may therefore result in alloimmunization and the production of alloantibodies (alloAbs). These alloAbs comprise anti-RBC Abs, antiHLA, anti-human platelet Ag (HPA) Abs, and anti-human neutrophil Ag (HNA) Abs. Anti-RBC immunization may result in hemolysis, whereas anti-HLA or anti-HPA Abs may result in complications such as fever and platelet transfusion refractoriness. Furthermore, antiHLA and anti-HNA immunization in the donor may result in a severe lung disorder called transfusion-related acute lung injury (TRALI). The Abs against red cell Ags may be IgM or IgG immunoglobulin classes. Some IgG or IgM can activate complement, and some IgG, crossing the placental barrier, may induce hemolytic disease of the fetus and newborn. Erythrocyte blood groups refer to antigenic molecules that are expressed on the surface of RBC and other cells, genetically trans­ mitted, and recognized by specific Abs. The polymorphism of such molecules explains their immunizing potential in situations such as transfusion, pregnancy, and transplantation. Blood groups can also interact with the environment and with infectious pathogens, leading to individual susceptibilities. For example, malaria is less severe in type O than non-O patients. Currently, ~390 different blood group Ags have been described, classified within ~45 different systems. Blood group Ags belong to two broad categories based on their biochemical nature: carbohydrate blood groups and protein blood groups. RBC Ags may be the target of autoantibodies (autoAbs) generating autoimmune hemolytic anemia. Some of them, mostly IgG, are active at 37°C, called “warm autoAbs,” and are most often directed against Rh Ags, whereas others, most often IgM, are active at 4°C, called “cold autoAbs,” and may be directed against ABO, HI, I, i, P, and other Ags. CHAPTER 118 Transfusion Therapy and Biology Carbohydrate blood groups are headed by the ABO system, which comprises two main Ags, A and B, encoded by two alleles, which are the A and B alleles, respectively. In addition to these active alleles, there is an inactive allele: O. Depending on the genotype, four different phenotypes are produced (Table 118-2). Other carbohydrate systems (H, P1PK, Lewis, I, GLOB and SID) share many characteristics with the ABO system. The A allele encodes the A enzyme, which binds the A-type sugar (GalNac) A to the H substrate (expressed by action of the H enzyme encoded by the H allele, which happens to be inactive in the Bombay phenotype); sugars are attached to protein substrates on the surface of the RBC and so forth. Carbohydrate Ags are ubiquitously distributed in the body. The ABO Ags, expressed on endothelial cells, are genuine “tissue” groups and may be involved in graft rejection. These Ags are not specific to humans but are shared by many species including viruses and bacteria. The presence of A and B Ags in the environment and, in particular, on the bacteria of the microbiota explains the synthesis of so-called “natural” or “regular” Abs, aside from any transfusion or pregnancy. Such Abs have a major hemolytic capacity as they bind complement and activate its cascade up to the membrane attack complex. This imposes donor-recipient stringent compatibility rules for RBCCs and whole blood transfusion and, albeit less stringently, for plasma and PC transfusion. Protein blood groups are headed by the Rh system for RBCs (Table 118-3). As these Ags are specific to humans, the occurrence of immunization can only occur upon allogeneic stimulation. Abs directed against Ags of RBC groups other than ABO must be detected before RBCC transfusion or transplantation and during pregnancy. Of the 45 RBC group systems described, five (Rh, Kell, Duffy, Kidd, and MNS) are routinely investigated due to the clinical significance of Abs and their frequency. Testing for all five types ensures routine transfu­ sion compatibility of 95%. The Rh system comprises nearly 56 Ags, the most immunogenic of which is the D Ag (RH1). The Rh system has two RH∗D and RH∗CE genes located on chromosome 1. The RH∗D gene codes for the RhD protein expressing the D Ag (RH1) present in 85%, 93%, and >99% TABLE 118-1  Blood Components: Collection and Manufacturing Processes ADDITIONAL COMPONENT PROCESSING (OPTIONAL TO MANDATORY) RATIONALE BLOOD OR APHERESIS COLLECTION AND INITIAL PROCESSING BLOOD COMPONENT Whole blood collection: Separation into RBCC and platelet-rich plasma (PRP) by slow centrifugation, followed by high-speed centrifugation of the PRP to yield one unit of platelets (most often subsequently pooled) and one unit of plasma. or RBCC from whole blood or from apheresis Leukocyte reduction Deleukocytation to <1–5.106 leukocytes per unit (highly recommended): initial whole blood filtration or RBC elective filtration (highly recommended) Irradiation: X-ray or gamma, ~25–35 Gy; most often units not older than 28 days after collection Separation into a RBCC, a plasma, and a “buffy coat” containing leukocytes and platelets by high-speed centrifugation, followed by pooling and slow-speed centrifugation of the buffy coat to produce a pooled platelet unit. Alternatively, the buffy coat may undergo high-speed centrifugation to produce a granulocyte unit that will be subsequently pooled. Apheresis collection: Various apheresis devices allow for the collection of BCs either as individual BCs such as plasma or PC (possibly double, such as double RBCC) or combined BCs, such as PC and plasma, or RBCC, platelets, and plasma. Plasma reduction Prevention of allergic reactions in patients with prior severe transfusion reactions Pediatric preparation Adjustment to low-weight recipients Cryopreservation (glycerol) PART 4 Oncology and Hematology PC from whole blood (individual units or pools of 4–6 units of ABO identical units) or from apheresis Suspension in a platelet additive solution (PAS). PAS contains ingredients such as acetate, potassium, phosphate, and magnesium to sustain platelet storage Leukocyte reduction (<1–5.106 leukocytes per unit) (highly recommended): initial whole blood filtration or PC elective filtration Pathogen reduction: Most often nucleic acid cross-linker and/or UV illumination Volume reduction Prevention of allergic reactions in patients with prior severe reactions Irradiation: X-ray or gamma, ~25–35 Gy; in general, on bags no older than 3 days after collection Pediatric Volume and content adjustment     Cryopreservation (DMSO) To ensure continuous availability in remote locations To ensure availability of platelets with rare HPA groups Plasma from whole blood or from apheresis Cryopreservation at –18°C (most often) VOLUME AND CONTENT STORAGE CONDITIONS AND DURATION Reduction of fever and chills Reduction of intracellular pathogens (including CMV) Reduction of alloimmunization 250–300 mL (including additive solution, no more than 40–50 mL of plasma) Hemoglobin: 22–40 g/dL Hematocrit: 50–70% Hemolysis ≤0.8% at issuing 4 +/– 2°C Duration depends on the additive solution: 25–42 days After irradiation: 24 h After plasma reduction: 24 h to 10 days depending on reduction methodology GVHD prevention in immunosuppressed patients or intrafamily transfusions     Lesser volume, 10% reduction in RBC content   Adjusted content   Most often to ensure availability of RBCCs with a rare blood group for immunized “public-negative” recipients or recipients with complex alloimmunizationsa Same Hb content Hematocrit: 40–80% Glycerol ≤1 g N2 or –80°C electric freeze drying N2: unlimited; –80°C: 30 years 7 days after thawing in suitable additive solutions, 24 h without additive solution Reduction of fever and chills Plasma orientation toward fractionation From 100 to 700 mL ≥2.1011 platelets pH ≥6.4 At 20–24°C and under permanent motion: 3–7 days or At 4°C without motion: up to 14–21 days If irradiated: <24 h Reduction of fever and chills Reduction of intracellular pathogens (including CMV infections) Reduction of alloimmunization     Reduction of transfusiontransmitted infections Prevention of GVHD         Prevention of GVHD       6 h after thawing (depending on cryopreservation procedure, may be resuspended in plasma) Shelf-life extension 200–300 mL Coagulation factors, including fibrinogen (≥2 g/L), factor VIII (≥0.5 IU/mL), protein C and S, antithrombin 1–2 years if cryopreserved Up to 28 days if kept unfrozen (Continued) TABLE 118-1  Blood Components: Collection and Manufacturing Processes ADDITIONAL COMPONENT PROCESSING (OPTIONAL TO MANDATORY) RATIONALE BLOOD OR APHERESIS COLLECTION AND INITIAL PROCESSING BLOOD COMPONENT Leukocyte reduction (<1–5.106 leukocytes per product): Initial whole blood filtration and/or plasma elective filtration Pathogen reduction: Nucleic acid cross-linker and/or UV illumination or solvent detergent treatment (most often on pooled products) Lyophilization To facilitate transportation and storage, as well as immediate availability, in remote locations Granulocyte concentrates from whole blood (pools of 10–20 ABOidentical units) or from apheresisb Irradiation (mandatory) Prevention of GVHD ≤650 mL ≤2.1010 granulocytes Whole blood Leukocyte reduction with a platelet-sparing device Peripheral blood mononuclear cells (apheresis) May undergo cryopreservation (N2) Cryoprecipitate (collected after thawing and centrifugation of plasma) Resuspension in plasma (10–15 mL) and cryopreservation aAntigen frequency below 1% to 1/1000 of the population and contraindication for using regular blood units, depending on country-specific regulations. bGranulocyte collection by apheresis requires donor preadministration of steroids and/or hematopoietic growth factor and exposure to heparin and hydroxyethyl starch during the apheresis procedure. Abbreviations: BC, blood component; CMV, cytomegalovirus; DMSO, dimethyl sulfoxide; GVHD, graft-versus-host disease; Hb, hemoglobin; HPA, human platelet antigen; N2, nitrogen gas; N/A, not applicable; RBC, red blood cell; RBCC, red blood cell concentrate; PC, platelet concentrate; UV, ultraviolet. of individuals of Caucasian, African, and Asian ancestry, respectively. The RH∗CE gene codes for RhCE proteins expressing C (RH2) and/ or c (RH4), and E (RH3) and/or e (RH4) Ags. The presence of the D Ag confers Rh “positivity,” while its absence confers Rh “negativ­ ity.” The RH∗D and RH∗CE genes determine eight main haplotypes (DCe, DcE, Dce, DCE, dce, dCe, dcE, and dCE) whose frequencies TABLE 118-2  ABO Blood Groups and Antibodies: Transfusion Compatibility GENOTYPE(S) ENZYME(S)/IMMUNODOMINANT SUGAR(S) PHENOTYPE A/A or A/O “A” transferase/N-acetylgalactosamine (GalNac) A Anti-B A or O A, 0b, Bb, or ABb A or A,B B/B or B/O “B” transferase/galactose (Gal) B Anti-A B or O B, O, Ab, or ABb B or A,B A/B “A” transferase and “B” transferase GalNac and Gal A,B None A,B or A or B or O A,B, Ob, or Ab or Bb A,B O/O Inactive Unconverted H antigen O Anti-A and Anti-B O 0, A, B, or A,B A or B or A,B or O aOrder of priority. bWithout high-titer anti-A and/or anti-B antibody. Abbreviations: PC, platelet concentrate; RBCC, red blood cell concentrate. (Continued) VOLUME AND CONTENT STORAGE CONDITIONS AND DURATION Reduction of fever and chills Reduction of intracellular pathogens (including CMV) Reduction of alloimmunization     Reduction of transfusiontransmitted infections         Room temperature ≤24 h after the end of collection CHAPTER 118 Reduction of posttransfusion fever and chills Reduction of intracellular pathogens (including CMV) Reduction of alloimmunization ~520 mL (including additive solution) At 2–4°C 21–35 days Transfusion Therapy and Biology Increased practicability Repeated administration Number of cells adjusted for a predetermined number of T lymphocytes 105–107 CD3+ cells/ recipient kg N2: unlimited Never frozen or thawed: <6 h N/A Cold-insoluble plasma proteins (fibrinogen, factor VIII, von Willebrand factor) 12 months After thawing, may be stored at 20–24°C for up to 6 h differ considerably among different geographical populations. The high diversity of the Rh Ags includes weak and/or partial expression. Identifying individuals (especially young females of childbearing potential and multitransfused patients) with a weak or partial D Ag is important to adequately select D-positive or -negative RBCs. Molecu­ lar biology is now routinely applied to resolve such situations. TRANSFUSION COMPATIBILITY REQUIREMENTS NATURAL ANTIBODIES RBCC PCa PLASMA TABLE 118-3  Red Blood Cell Group Systems and Antibodies: Clinical Significance and Transfusion Recommendations ISBT NO./ SYSTEM SYMBOL/GENE(S) ANTIGENS (NO.) MAIN ANTIBODIES (ANTI-) 1/ABO ABO/ABO A, B None to severe; immediate and/or delayed 2/MNS MNS/GYPA, GYPB, (GYPE) M None (except in extremely rare cases if active at 37°C) N None (may be clinically significant in the case of the rare N–S–s–U– phenotype) S, s None to moderate (rare) None to severe (rare) Ag-negative RBCC U Mild to severe Mild to severe (one reported case requiring an intrauterine transfusion) 3/P1PK P1PK/A4GALT P1 None to moderate; delayed (rare) P1, Pk, P (Tja) None to severe None to severe Ag-negative RBCC 4/Rh RH/RHD, RHCE D, C, E, c, e Mild to severe; immediate or delayed PART 4 Oncology and Hematology 6 /Kell KEL/KEL K Mild to severe; delayed Mild to severe (rare) Ag-negative RBCC 7/Lewis LE/FUT3 Lea, Leb None (rare cases of hemolytic reactions) 8/Duffy FY/ACKR1 Fya, Fyb Mild to severe (rare); immediate/delayed Fy3, Fy5 Mild to moderate; immediate (rare)/delayed 9/Kidd JK/SLC14A1 Jka, Jkb None to severe; immediate or delayed Jk3 None to severe; immediate or delayed 18/H H/FUT1 H (Bombay) None to severe; immediate/ delayed 20/Globoside GLOB/B3GALNT1 P None to severe None to mild Ag-negative RBCC Abbreviations: Ab, antibody; Ag, antigen; HDFN, hemolytic disease of the fetus and newborn; IAT, indirect antiglobulin test (indirect Coombs test); ISBT, International Society of Blood Transfusion; RBCC, red blood cell concentrate. The Kell system comprises 38 Ags, one of which is routinely deter­ mined: the K antigen (KEL1); 9% and 2% of individuals of Caucasian and African ancestry are K positive (KEL:1), respectively, whereas 91% and 98%, respectively, are K negative (KEL:–1). The immunogenicity of Kell is third behind the ABO and Rh systems. The Kell protein is linked to another blood group protein called Kx. The rare absence of this protein (controlled by a gene on X) is associated with a weak KEL Ag, acanthocytosis, shortened RBC survival, and a progressive form of muscular dystrophy that includes cardiac defects. This rare condition is called the McLeod phenotype. The Duffy system (FY) comprises five Ags, two of which are rou­ tinely tested: the Fya Ag (FY1), coded by the Fya allele, and the Fyb Ag (FY2), coded by the Fyb allele. Depending on the combination of alleles, three common phenotypes are expected: Fy (a+b+), which has the two alleles Fya and Fyb; Fy (a+b–), which has only the Fya allele in a double dose; and Fy (a–b+), which has only a double dose of the Fyb allele. A particular phenotype characterized by the absence of the Fya and Fyb Ags, the Fy(a–b–) phenotype, is exclusive (with some excep­ tions) to individuals of African ancestry where it can reach frequencies of 70–100% depending on the population. It is linked to the presence of a double dose of a silent FY*0 allele. This distribution may be related to the fact that the Fy Ags serve as receptors for Plasmodium vivax and therefore the Fy(a–b–) phenotype. However, these individuals may develop Abs against two high-frequency Ags (FY3 and FY5) after transfusion or pregnancy. They may also have low a granulocyte count but are not associated with any disease. The Kidd system (JK) comprises three Ags, two of which are routinely tested: the Jka Ag (JK1), coded by the Jka allele, and the Jkb HEMOLYSIS CHARACTERISTICS RBCC TRANSFUSION RECOMMENDATIONS TRANSFUSION HDFN None to moderate (rarely severe) Ab-negative RBCC None (except in extremely rare cases if active at 37°C) Compatible RBCC (negative IAT at 37°C) Ag-negative red cells in the case of sickle cell disease None Compatible RBCC (negative IAT at 37°C) Ag-negative RBCC in the case of N–S–s–U– phenotype Ag-negative RBCC None Compatible RBCC (negative IAT at 37°C) Mild to severe Ag-negative RBCC None Compatible RBCC (negative IAT at 37°C) Mild to severe (rare) Ag-negative RBCC Mild (rare) (no data for anti-Fy5) Ag-negative RBCC Mild to moderate (rare) Ag-negative RBCC None to mild Ag-negative RBCC Not none Ag-negative RBCC Ag (JK2), coded by the Jkb allele. Depending on the combinations of alleles, three common phenotypes are seen: Jk(a+b+) displaying the two alleles Jka and Jkb, Jk(a+b–) displaying only the Jka allele in a double dose, and Jk(a–b+) displaying only a double dose of the Jkb allele. A particular phenotype is characterized by the absence of the Jka and Jkb Ags: the Jk(a–b–) phenotype found in Polynesian populations. It is linked to the presence of a double dose of a silent JK∗0 allele. These people may develop Abs against the high-frequency anti-JK3 Ag after transfusion or pregnancy. The MNS system comprises 50 Ags, four of which are routinely tested. Two genes (GYPA, GYPB) encode two pairs of so-called “antithetical” Ags. The M (MNS1) and N (MNS2) pair Ags encoded by the M and N alleles, respectively, are branched on the glycophorin A molecule. Their combination will determine whether or not they are present. M+ and N+ subjects have both alleles; an M+, N– subject is homozygous for the M allele; and an M–, N+ subject is homozygous for the N allele. The same holds true for the other pair of Ags, S (MNS3) and s (MNS4) expressed on glycophorin B. Therefore, an M+, N–, S–, s+ subject (in international nomenclature, this is written as MNS:1,–2,–3,5) will be homozygous for the M and s alleles. A rare phenotype, S–s–, found exclusively in individuals of African ancestry, can develop an Ab against the high-frequency U Ag (MNS5) after transfusion or pregnancy. ■ ■RARE RBC PHENOTYPES Some patients present with rare genotype/phenotype assortments, and their RBCs display so-called private Ags or, conversely, lack public Ags (i.e., widely shared Ags) toward which the patient may develop an immune response when exposed to these Ags. Public-negative immunized individuals are virtually impossible to transfuse using conventional blood bank resources and require access to designated blood banks that have access to rare blood programs. Their primary responsibility is to identify and collect blood from donors exhibiting particular Ag displays on their RBCs or platelets that are uncommon in the given jurisdiction. Specific ethnic populations may be targeted, as some may display genotype specificities, such as the Bombay group in southwestern Indians. Several hemoglobinopathies, such as sickle cell disease, are more common in individuals of African ancestry. Such patients may display RBC phenotypes that are uncommon in coun­ tries in the Northern Hemisphere, resulting in difficulties adequately identifying donors to match the need, as a last resort, for highly valued cryopreserved BCs. CLINICAL INDICATIONS AND EFFICACY ASSESSMENT OF BLOOD COMPONENTS BCs are life-saving therapies but also scarce resources. Furthermore, transfusion may result in well-identified adverse reactions as well as more ill-defined adverse reactions, including inflammation and therapeutic inefficacy. As highlighted in patient blood management programs, transfusion should be considered within a multidisciplinary approach that includes optimization of hematopoiesis and minimiza­ tion of blood loss during surgical interventions. Clinical indications of BCs as well as means to assess therapeutic efficacy are detailed in Table 118-4. ADVERSE REACTIONS TO BLOOD COMPONENTS Adverse reactions to transfused BCs are most commonly non-lifethreatening, although serious reactions can present with mild symp­ toms. Transfused patients should be closely monitored for warning signs suggestive of adverse reactions, as described in Table 118-5. When an adverse reaction is suspected, the transfusion must be stopped while the recipient’s clinical status is assessed, and supportive care is initiated as needed. An average of 37 transfusion-associated fatalities with possible to definite imputability were reported yearly to the U.S. Food and Drug Administration (FDA) between 2017 and 2021 among ~15 million transfused BCs. Most frequent causes of death were transfusion-associated circulatory overload (TACO) (32%), followed by TRALI (21%), hemolysis (21%), and microbial contamina­ tion (13%). Adverse reactions to BCs may result in immune and nonimmune mechanisms. Immune-mediated reactions are often due to recipient or donor alloimmunization and the presence of preformed recipient or donor Abs. Nonimmune causes of reactions are from the physical or chemical properties of BCs or from pathogens present in the BC. ■ ■IMMUNE-MEDIATED ADVERSE REACTIONS Hemolytic Transfusion Adverse Reactions  Immune-mediated acute hemolysis occurs when the recipient preformed Abs lyse trans­ fused donor RBCs and may occur during or 24 h after transfusion. The anti-A or anti-B Abs are responsible for most of the most severe reactions, which can be fatal. However, alloAbs directed against other RBC Ags (i.e., Rh, Kell, and Duffy) are also responsible for severe hemolytic reactions. Such dramatic reactions are usually caused by a failure in product or patient identification, erroneous blood grouping, or unidentified anti-RBC alloimmunization in the recipient. Hemoly­ sis, most often of lesser severity, may also occur upon transfusion of BCs containing incompatible plasma with a large amount of alloAbs directed against the recipient’s RBCs. This may typically occur after transfusion of a PC containing ABO-incompatible plasma. Estimated frequencies of acute and chronic hemolytic adverse reactions are 1–10 and 5–40 per 105 transfused BCs, respectively. Mechanisms of transfusion hemolytic reactions are described in Fig. 118-1. Prevention of hemolytic reactions relies on pretransfusion test­ ing of potential recipients. Testing will include determination of the ABO D phenotype (and anti-ABO Abs) as well as additional typing for the other main Rh Ags (CcEe), K Ag of the Kell system, and more rarely, Duffy (Fya and Fyb), Kidd (Jka and Jkb), and MNS (S and s) Ags, depending on the clinical setting. These determinations are most often performed by serology. However, molecular typing is increas­ ingly being used to predict RBC phenotype and facilitate the selection of a compatible component. Special care must be taken to verify the patient’s identity and apply adequate tube labeling. A double ABO determination performed separately may be considered, especially in the absence of a systematic crossmatch. Testing will also include the screening and identification of alloAbs directed against RBC Ags other than ABO. This screen is performed by mixing patient serum with type O RBCs expressing Ags from most blood group systems and whose extended phenotype is known. The specificity of the alloAb is identified by correlating the presence or absence of Ag with the induced—or not—agglutination. Special attention should be paid to patients receiving monoclonal Ab treat­ ment that may bind to erythrocytes in vivo (such as anti-CD38 IgG treatment for multiple myeloma) and therefore interfere with alloAb screening. Such interference may be offset by sample dithiothreitol pretreatment. Crossmatching between the recipient plasma/serum and the selected RBCs may be performed, especially when the recipient is alloimmu­ nized against RBC or is frequently transfused, as well as in specific clinical settings such as sickle cell disease, even if the Ab screening is negative. CHAPTER 118 The selection of a compatible BC should consider pretransfusion testing as well as the recipient’s clinical status. In the case of D-negative patients, every attempt must be made to provide Rh-negative RBCC to prevent anti-D alloimmunization. In an emergency, D-positive RBCC can be safely transfused to a D-negative patient who lacks anti-D. How­ ever, an estimated 20–22% of RBCC recipients will become alloimmu­ nized and produce anti-D Abs after transfusion with D-positive RBCs. Such alloimmunization can occur after PC transfusion, although at a much lower frequency (~1%). Whenever possible, females with child­ bearing potential (to include prepubertal girls) should be transfused with D- and K-compatible RBCCs and D-compatible PCs to prevent alloimmunization and protect a future fetus/newborn from an alloimmunemediated hemolytic disease. D-negative females with childbearing potential who are transfused with BCs containing D-positive RBCs should receive anti-D Ab to prevent allosensitization. Transfusion Therapy and Biology Hemolysis, most often of lesser severity, may also occur after trans­ fer of alloAbs directed against the recipient’s RBC Ags. Such ABO “plasmatic” incompatibility, called “minor ABO incompatibility,” will occur mainly with PC transfusions, where platelets are suspended in ~100–300 mL of plasma (depending on whether part of the plasma is substituted by additive solution). BCs containing plasma with hightiter anti-A/B Ab may induce a hemolytic reaction. When the transfu­ sion of ABO-identical (vs ABO-compatible) PCs is not feasible, PCs provided by donors with low-titer anti-A/B only should be preferred. While there is no universal definition of high-titer Abs, a threshold titer of 1/64 (as assessed by hemagglutination) may be appropriate. The use of an additive solution in PCs substantially mitigates this risk. Lastly, ABO plasmatic incompatibility can lead to the formation of immune complexes with soluble A and/or B Ags and ensuing inflam­ mation and platelet activation. Acute hemolytic reactions may present with hypotension, tachypnea, tachycardia, fever (+1–2°C), chills, chest and back pain, hemoglobin­ uria, and hemoglobinemia. In the most severe cases, disseminated intravascular coagulation (DIC), acute renal failure, shock, and death may occur. Delayed hemolytic reactions, with icterus and persisting or wors­ ening anemia as the main clinical manifestations, result from an anamnestic response. Such reactions may occur in patients previously sensitized to RBC Ags who have a negative alloAb screen at the time of transfusion due to low Ab levels. The alloAb is detectable 1–2 weeks after the transfusion. Diagnosis of transfusion-associated hemolysis relies on persis­ tent and/or worsening anemia, depleted plasma haptoglobin levels, transfusion (not applicable to CCIa >7.5 to 10 within 1 h and Prevention and/or resolution 25–30 mL/kg Sickle cell disease: reduced Increased Hb (+1 g/dL) and related symptoms, clinical > 4.5 to 5 within 24 h after COMPONENT THERAPEUTIC INDICATION GOAL DONOR/RECIPIENT COMPATIBILITY DOSAGE EFFICACY EVALUATION Reduction of anemiapercentage of HbS hematocrit (+3%) improvement of bleeding whole blood–derived PCs) 0.5–0.7 × 1010 platelets/kg 1 unit at a time (250–350 solution), repeated per mL, including additive clinical status and Hb (apheresis or pooled level Additional compatibility may be required compatible (cellular) with low-titer antiHLA compatible (negative lymphocyte depending on the clinical setting and ABO identical preferable; if not, ABO A/B Ab; RhD compatible preferred in RhC/c/E/e; Kell-compatible RBCCs if multitransfused whenever possible. Improve systemic and tissue oxygenation ABO compatible (cellular) and ABO childbearing-age females, and if RhD compatibility in young and identical when achievable. PART 4 Oncology and Hematology premenopausal women screening results. multitransfused improved hemostatic capacity compared with Replace altered RBCs with donor RBCs and Cold stored platelets, despite lower in vivo compensate for hemolysis, prevention of survival, have maintained and possibly Correct impaired primary hemostasis, sickle cell occlusive crisis including vessel healing neonates and patients with severe thrombocytopenia relation with clinical symptoms): <7 g/dL for patients with preexisting cardiovascular disease (<8 g/dL) as undergoing orthopedic surgery, cardiac surgery, or in the absence of fever or infection, ≤10,000/μL to well as for patients with acute coronary disease Hb below a given threshold (to be considered in Platelet level below a given threshold: ≤5000/µL Thrombocytopenia-related bleeding disorders: (<9–10 g/dL). Such thresholds do not apply to Anemia and/or tissue ischemia (treatment or Not recommended: nutritional anemia (iron, hemodynamically stable, except for patients Treatment (cold or room temperature PC) or and chronic transfusion-dependent anemia. RBC exchange: Anemia/sickle cell crisis in hemoglobinopathies (sickle cell disease, prevention (room temperature PC) vitamin B12, or folate deficiency) TABLE 118-4  Blood Components: Clinical Use thalassemia) RBCC Transfusion: prevention) blood–derived platelets or temperature (most often) single donor apheresis), PC (from pooled whole maintained at room (Continued) Reduced antibody levels (e.g., cold/cryopreserved platelets) anti-HLA antibodies prior to ABO compatible (plasma) 45–60 mL/kg Improved disease-specific Not determined Reduced bleeding disorder recovery in case of TTP) organ transplantation) symptomatology (i.e., apyrexia and platelet Infection resolution ABO compatible (plasma) 10–15 mL/kg neonates to HPA immunized mother (fetal refractoriness related to the presence of neonatal alloimmune thrombocytopenia) crossmatch) or HLA identical in case of HPA compatible in thrombocytopenic anti-HLA Ab missing elements of coagulation or fibrinolysis cascade, as well as elements to heal injured Ab in case of TTP, excess cholesterol, etc.); and/or immunomodulatory factors such as Deplete pathogenic elements in the blood Correct impaired hemostasis by providing (autoantibodies such as anti-ADAMTS-13 plasma may also bring anti-inflammatory Provide Abs against relevant pathogens room temperature stored platelets vessel endothelium immunoglobulin Infectious disease (convalescent plasma containing Plasma exchange (plasma or combined plasma and lacking enzyme (e.g., thrombotic thrombocytopenic 20,000/μL if fever or infection; ≤50,000/μL if surgery, DIC, endoscopy, invasive procedures; ≤80,000/μL if Pathogenic Ab removal (e.g., anti-HLA Ab prior to pathogen-specific Abs): Argentina hemorrhagic Pathogenic Ab removal and supplementation of fever, viral respiratory infections (experimental) Coagulation factor–related bleeding disorders Acute hypovolemic coagulopathy (see below) Acute hypovolemic coagulopathy (see below) microangiopathy or Guillain-Barré syndrome) Immune thrombocytopenia, thrombotic microangiopathy, and heparin-induced thrombocytopenia: Not recommended neurosurgery, eye surgery, or ECMO kidney transplantation) Transfusion: albumin): Plasma (thawed frozen, at room temperature, maintained at 4°C or never frozen and freeze-dried) or at 4°C 4–5 units Increased plasma fibrinogen enhancement effect) N/A 105–107 T lymphocytes/kg Disease specific (remission) stabilization until recovery status Normovolemia; bleeding Normovolemia; bleeding clinical status Infection resolution (or from neutropenia) (0.3–1 g/L) resolution resolution ABO compatible 1–2 × 1010, repeated per PC ratio, repeated per compatibility 1 RBCC/1 plasma/0.25 Willebrand factor, and factor XIII ABO compatibility is not required 10–15 mL/unit, pool of anti-A/B Ab Repeated per clinical clinical status ABO-identical or group O with low-titer Standard RBCC, PC, and plasma transfusion Appropriate ratio is under investigation; a ratio of 1 RBCC/1 plasma/0.25 PC (platelet content relation to granulocytopenia or granulocyte maintained at 4°C and without an additive transfusion Balanced provision of blood components Correct impaired granulocyte function in hematopoietic cell transplantation Graft-versus-leukemia effect (and graft Provision of fibrinogen, factor VIII, von of a whole blood) is currently favored solution and related dilution Number of platelets transfused x 10 x Body surface area (m ) ( ) ( ) = dysfunction Whole blood Acute hypovolemic coagulopathy requiring massive PC, and plasma) Acute hypovolemic coagulopathy requiring massive Cryoprecipitate Acute bleeding coagulopathy, type II (dysfunctional disease, hemophilia A in the absence of factor VIII granulocytes (CGD). Neutropenia can be acquired Donor mononuclear cells Relapse of malignant hemopathy after allogeneic factor) or type III (absent factor) von Willebrand Severe refractory bacterial or fungal infection (chemotherapy) or congenital. Formal proof of (mainly soft tissues and lung) in patients with neutropenia (<100/μL) or with dysfunctional CCI Postransfusion count /µL –pretransfusion count /µL efficacy is lacking. concentrates Granulocyte concentrates Multicomponent (RBCC, (apheresis or a pool of whole blood–derived aCCI calculation: granulocytes) Abbreviations: Ab, antibody; CCI, corrected count increment; CGD, chronic granulomatous disease; DIC, disseminated intravascular coagulation; ECMO, extracorporeal membrane oxygenation; Hb, hemoglobin; HLA, human leukocyte CHAPTER 118 antigen; N/A, not applicable; RBC, red blood cell; RBCC, red blood cell concentrate, PC, platelet concentrate; TTP, thrombotic thrombocytopenic purpura. Transfusion Therapy and Biology TABLE 118-5  Transfusion Adverse Reactions: Main Warning Signs Fever (≥38°C) +1–2°C within 4 h FNHTR Anti-HLA immunization and cognate Ag in the blood product TRALI (with dyspnea at the forefront) +1–2°C within 15 min +/–: • Chills • Dyspnea • Hypotension • Digestive disorders • Disseminated intravascular coagulation • Hemoglobinuria >2°C Transfusion-transmitted bacterial infection Hypotension (≥30 mmHg decrease in systolic blood pressure) Hemolytic shock Anaphylactic shock Septic shock TRALI (with dyspnea at the forefront) Dyspnea TRALI (within 6 h of transfusion) TACO (within 12 h of transfusion) Severe allergy (immediate; within 4 h) Hemoglobinuria Intravascular hemolysis • Immunologic • Mechanical • Toxic • Thermic PART 4 Oncology and Hematology Rash <2/3 of the body within 2–3 h Minor allergy >2/3 of the body during or within 2–3 h Severe allergy >2/3 of the body within 5 min Associated with dyspnea and shock Icterus Delayed hemolysis New alloantibody Alloimmunization Rash, diarrhea, and fever occurring 2 days to 6 weeks after transfusion GVHD Gum bleeding, purpura 5–12 days after transfusion Posttransfusion purpura Cardiac, hepatic, and/or renal insufficiency in frequently transfused patients Posttransfusion iron overload Top-down investigation after a blood donor is subsequently found to be infected Transfusion-transmitted infection Bottom-up investigation after another recipient of a same blood donation is found to be infected Infectious symptoms within 6 months Abbreviations: Ag, antigen; FNHTR, febrile nonhemolytic transfusion reaction; GVHD, graft-versus-host disease; HLA, human leukocyte antigen; TACO, transfusion-associated circulatory overload; TRALI, transfusion-related acute lung injury. hemoglobinemia and hemoglobinuria, and elevated plasma lactate dehydrogenase and unconjugated bilirubin. The direct antiglobulin test (DAT, or direct Coombs test) that detects immunoglobulin, and pos­ sibly complement (C3d), on the surface of the recipient’s RBC will most often be positive (Fig. 118-2). Similarly, a positive indirect antiglobulin test (IAT, or indirect Coombs test) that detects anti-RBC alloAb in the serum will also be positive. An elution of the Ab on the surface of the RBC may allow for the identification of the culprit alloAb. The management of an immune-mediated acute hemolytic transfu­ sion reaction is mainly supportive. Prompt interruption of the trans­ fusion, biological workup, and a thorough clerical check to prevent a possible second misidentified transfusion are crucial initial steps. Vigorous hydration with isotonic saline and diuretics to maintain urine output is recommended. Although often self-limiting, acute hemolysis may also require forced alkaline diuresis, correction of elec­ trolyte abnormalities, and pressor support as needed. In patients with DIC and severe bleeding, PC, plasma, and cryoprecipitate or fibrino­ gen may be required. When transfusion of incompatible RBCCs is unavoidable, prophylaxis with steroids (100 mg of hydrocortisone) just before the transfusion and repeated 24 h later and polyvalent immunoglobulin (1.2–2.0 g/kg per day over 2–3 days, initiated just before the transfusion) have been successfully used to prevent or minimize acute and delayed hemolysis. Polyvalent immunoglobulin, Transfusion-transmitted bacterial infection Hemolysis Anaphylaxis anticomplement (C3) Ab, anti-B-cell Ab, or plasma exchange may be considered in case of severe posttransfusion hyperhemolysis in sickle cell patients. Immune-mediated hemolysis may also occur after allogeneic hema­ topoietic transplantation (most often involving a peripheral blood stem cell graft) or, more seldomly, solid organ transplantation. Minor ABO incompatibility, with subsequent red cell destruction in the recipient, is the most common cause of clinically significant hemolysis in such cases. Viable donor B lymphocytes, called “passenger lymphocytes,” transferred passively with the graft, may produce alloAbs (including anti-D or anti-A1 in an A2 donor) that target recipient red cells. Such hemolysis has been reported to develop 5–14 days after transplanta­ tion. Reduced-intensity conditioning regimens and cyclosporine as prophylaxis against GVHD or rejection have been associated with increased risk. Transfusing RBCs compatible with the graft donor and the use of GVHD prophylaxis able to target B cells (e.g., methotrex­ ate) have significantly reduced the incidence of passenger lymphocyte syndrome. Allogeneic hematopoietic transplantation may also result in acute hemolysis due to incompatible donor-derived red cell (and precursor) destruction by the recipient alloAbs (i.e., major ABO incompatibility). Prolonged pure red cell aplasia may occur in such a situation. Graft deserythrocytation will reduce the risk of early acute hemolysis. A Predominantly intravascular acute hemolysis occurring during or within 24 hours following transfusion Mastocyte Cytokines Chemokines TNFa IL1, 6, 8 A C1 C3a/C5a Anti-A Ab C5/C9 A Membrane attack complex formation RBC transmembrane pore Osmotic i.v. hemolysis B Predominantly extravascular acute or delayed (3 to 10 days after transfusion) hemolysis Macrophage C1 C3b RBC lysis Anti-Jka Ab Jka C3b C3d C Predominantly extravascular acute or delayed (3 to 10 days after transfusion) hemolysis Macrophage Anti-D Ab D FIGURE 118-1  Mechanisms of transfusion hemolytic reactions. A. Acute responses will involve preexisting antibodies (Abs), naturally occurring anti-A/anti-B IgM or IgG directed against other RBC antigens (Ags) and resulting from prior sensitization. Upon interaction with cognate antigen on transfused red blood cells (RBCs), recipient allogeneic Ab (alloAb), mostly natural anti-A/anti-B IgM, may fix and activate complement up to C5/C9. Formation of membrane attack complex (MAC) will create pores in transfused RBCs with resulting intravascular hemolysis, release of toxic moieties including free hemoglobin responsible for end-organ damage including renal failure, and tissue factors contributing to occurrence of disseminated intravascular coagulation (DIC). B. Alternatively, complement activation may be incomplete, as typically observed in a delayed hemolytic transfusion reaction involving neoformed allogeneic IgG. In such cases, complement activation up to C3 results in C3b-mediated opsonization of RBCs, extravascular hemolysis, and clearance through immunophagocytosis. Anemia and jaundice will be the primary clinical manifestations. C. Lastly, alloAb may not fix complement while ensuring antibody-dependent cellular cytotoxicity (ADCC)–mediated phagocytosis of targeted RBC. (Adapted from SR Panch et al: Hemolytic transfusion reactions. N Engl J Med 381:150, 2019.) Endothelium alterations Capillar permeability Vasodilation/Hypotension/Shock Fever DIC Hemoglobinemia Hemoglobinuria Albumin Haptoglobin HemopexinA Vasoconstriction Acute renal failure/ tubular necrosis Elimination Nitric oxide scavenging Hemoglobin Dimers Ferric heme CHAPTER 118 Transfusion Therapy and Biology Unconjugated bilirubin + Albumin Low-level hemoglobinemia Conjugated bilirubin Partial degradation of membrane proteins Spherocytes Microspherocytes Urobilinogen Stercobilinogen Unconjugated bilirubin + Albumin Low-level hemoglobinemia Conjugated bilirubin RBC lysis Partial degradation of membrane proteins Spherocytes Microspherocytes Urobilinogen Stercobilinogen Positive test result Indirect Coombs test/indirect antiglobulin test PART 4 Oncology and Hematology Direct Coombs test/direct antiglobulin test Positive test result Antihuman Abs Antigens on the red blood cell surface Human anti-RBC Abs FIGURE 118-2  Direct and indirect Coombs test. The direct Coombs/antiglobulin test detects the presence of Abs (or complement) on the surface of erythrocytes. The indirect Coombs/antiglobulin test detects Abs in the serum that may bind Agglutination of red blood cells occurs, because human Abs are attached to RBC(s). Antihuman Abs are added to the solution. Recipient’s Abs that target the donor’s RBC(s) form antibody-antigen complexes. to donor erythrocytes. Abs, antibodies; RBC, red blood cell. (Adapted from http://upload.wikimedia.org/wikipedia/commons/1/1c/coombs_test_schematic.png.) Donor’s blood is added to the serum. Recipient’s serum is obtained, containing Abs. Agglutination of RBC(s) occurs, because human Abs are attached to RBC(s). The patient’s washed RBC(s) are incubated with antihuman Abs. Blood sample from a patient with immunemediated hemolytic anemia: Abs are shown attached to antigens on the RBC surface. Polyvalent immunoglobulin may contain high titers of anti-A (mostly) and/or anti-B Abs and induce acute hemolysis, most often of limited severity. Such hemolysis is particularly described in group A or AB children receiving high-dose immunoglobulin, notably for Kawasaki’s disease, as well as in adults treated for thrombotic thrombo­ cytopenic purpura. A similar mechanism may lead to hemolysis after anti-D immunoglobulin treatment for immune thrombocytopenia in RhD-positive patients. Nonimmune mechanisms of transfusion-associated hemolysis include thermal (overheated or cold BCs), osmotic (concurrent hypoosmotic perfusion), and mechanical (pressure related to high-flow transfusion filtering during cell saver processing) mechanisms. Autoimmune and drug-induced hemolytic anemias may be exacer­ bated by transfusion and can therefore mimic hemolytic transfusion reactions. Transfusion of RBCs with enzymatic defects may mimic immune-mediated hemolysis as well. Notably, severe hemolytic reac­ tions in patients receiving long-term transfusions for hemoglobinopa­ thies (mainly sickle cell disease) can precipitate bystander hemolysis, in addition to clearing transfused red cells. The mechanisms of this hyper­ hemolytic transfusion reaction may be a mediated RBC hemolysis-related systemic inflammatory response and resulting lysis of red cell precur­ sors by macrophages. This process may be immediate or delayed, with hemoglobin levels falling below the pretransfusion values, often to life-threatening levels. Further RBCC transfusion typically exacerbates ongoing hemolysis, with the exogenous (transfused) allogeneic Ags probably triggering further nonspecific hemolysis. Febrile Nonhemolytic Transfusion Reaction  The most fre­ quent reaction associated with the transfusion of cellular BCs is FNHTR (up to 300 per 105 BCs). This reaction is characterized by chills and rigors and a ≥1°C rise in body temperature and is caused by pro­ inflammatory cytokines in the BC or by recipient Abs directed against donor cell Ags present in the BC. FNHTR is diagnosed when other causes of fever, notably infection and hemolysis, have been excluded. Leukocyte reduction, especially prestorage, can prevent the occurrence of FNHTR. Moreover, the use of additive solutions decreases FNHTR frequency associated with PC transfusion. Premedication with anti­ pyretics has generally proven ineffective at decreasing the rate of such reactions and may mask relevant clinical symptoms. Allergic Reactions  Most allergic transfusion reactions are mild and include rash, pruritus, urticaria, and localized edema. More rarely, allergic reactions may be severe to life-threatening with an anaphylactic reaction that can involve bronchospasm, respiratory distress, hypoten­ sion, nausea, vomiting, and shock. Frequencies of mild and severe allergic reactions are ~100 and ~5 per 105 BCs, respectively. Allergic reactions are related to plasma proteins found in transfused components. Mild reactions may be treated by temporarily stopping the transfusion and administering antihistamine drugs. Patients with a history of aller­ gic transfusion reaction may be premedicated with an antihistamine, although there is no consensus on this issue. Cellular components can be washed to remove residual plasma for extremely sensitized patients. Most of the allergic presentation may not depend on preformed Abs and may be attributable to soluble mediators triggering histamine and serotonin release from platelets and leukocytes. An anaphylactic reac­ tion may occur after the transfusion of only a few milliliters of the BC. Treatment includes stopping the transfusion, maintaining vascular access, and administering adrenaline (0.3–0.5 mg subcutaneously). Additional treatment with steroids, antihistamine drugs, and bronchodi­ lators may also be required. Patients who are IgA deficient (<1% of the population) may be sen­ sitized to this immunoglobulin isotype and may be at risk of anaphy­ lactic reactions associated with plasma transfusion. As a precaution, individuals with severe IgA deficiency should therefore receive, where available, IgA-deficient plasma and washed cellular BCs. Patients who have anaphylactic or repeated allergic reactions to BCs should be tested for IgA deficiency. It should be noted that the importance, or even the reality, of such a transfusion-related allergic risk is currently debated. Graft-Versus-Host Disease  GVHD is an extremely rare adverse reaction caused by transfusion, although it is a frequent complication of allogeneic hematopoietic transplantation. Transfusion-related GVHD is mediated by engrafted donor T lymphocytes in a recipient unable to reject such allogenic lymphocytes (as in severely immunosuppressed patients or patients homozygous for an HLA haplotype shared with the donor). Such donor T lymphocytes interact with host HLA Ags and mount an immune response, which is manifested clinically by the development, 5–10 days after transfusion, of cytopenia, fever, a characteristic skin rash, diarrhea, and liver function abnormalities. Transfusion-associated GVHD is highly resistant to treatment with immunosuppressive therapies as well as ablative therapy followed by allogeneic bone marrow transplantation and is fatal in >90% of cases. Prevention in at-risk patients relies on the irradiation of cellular BCs (minimum of 25 Gy) or treating BCs with pathogen reduction technol­ ogy that will deplete all living cells in the component. At-risk patients include patients with inherited immune deficiency, patients undergo­ ing autologous or allogeneic hematopoietic transplantation, patients treated with immunosuppressive drugs such as purine or pyrimidine analogues, anti-CD52 Ab, or antithymocyte globulin, fetuses receiving intrauterine transfusions, and recipients of BCs provided by a blood relative. Because granulocyte concentrates contain a large number of lymphocytes, they should always be irradiated. CHAPTER 118 Transfusion-Related Acute Lung Injury  TRALI is character­ ized by the occurrence or worsening of hypoxia and noncardiogenic pulmonary edema with bilateral interstitial infiltrates on chest x-ray during or within 6 h after transfusion, although delayed cases may occur up to 72 h later. Frequency of TRALI is BC dependent and ranges, on average, from 0.5 to 10 per 105 BCs. TRALI may be dif­ ficult to distinguish from other causes of hypoxia, such as circulatory overload, and is among the most common causes of transfusion-related fatalities. Treatment is supportive only. TRALI usually results from the transfusion of donor plasma that contains high-titer anti-HLA class II Abs that bind recipient cognate Ag. Anti-HLA class I and anti-HNA Abs may also be involved. TRALI mediated by cytokines and chemo­ kines in the absence of an HLA-mediated interaction may occur also. Leukocytes, especially when primed by either a bacterial moiety such as lipopolysaccharide or a cytokine/chemokine, aggregate in the pul­ monary vasculature and release inflammatory mediators. The transfu­ sion of plasma and PCs from male donors and nulliparous or parous female donors without anti-HLA Abs has significantly reduced the risk of TRALI where implemented. Recipient factors associated with an increased risk of TRALI include smoking, chronic alcohol use, shock, liver surgery (transplantation), cancer surgery, mechanical ventilation, and positive fluid balance. Transfusion Therapy and Biology Posttransfusion Purpura  This rare reaction (~1/105 BCs) is defined as a thrombocytopenia-related bleeding disorder developing 5–12 days after PC (and more rarely RBCC) transfusion, predominantly in women. Platelet-specific alloAbs are found in the recipient, most fre­ quently anti-HPA-1a in HPA-1a-negative alloimmunized individuals. The delayed thrombocytopenia is due to a secondary increased produc­ tion of alloAbs. The mechanisms for the destruction of the patient’s own platelets remain unclear. Management is mostly supportive but may require polyvalent immunoglobulin, glucocorticoids, or plasma exchange. Additional platelet transfusions may worsen the thrombocy­ topenia or be associated with poor increments. Prevention of recurrence includes use of washed BCs or BCs from HPA-compatible donors. Alloimmunization/Platelet Refractoriness  A recipient may become alloimmunized to a number of Ags on cellular blood elements and plasma proteins. AlloAbs to RBC Ags are detected during pre­ transfusion testing, and their presence may delay finding Ag-negative crossmatch-compatible products for transfusion. Women of childbear­ ing age who are sensitized to RBC Ags (i.e., D, c, E, Kell, or Duffy) are at risk of bearing a fetus with hemolytic disease of the fetus or new­ born. Ag matching is the only pretransfusion selection test to prevent RBC alloimmunization, which is found to occur with a frequency of ~100/105 RBCC transfusions. Alloimmunization to Ags on leukocytes and platelets, most often anti-HLA Abs, can result in refractoriness to PC transfusions (as defined by a low increase in platelet count after transfusion). Once alloimmunization has developed, HLA-compatible (crossmatched) PCs should be preferred if available. If not, repeated PCs at shortened intervals may be considered. Use of leukocytereduced cellular BCs will reduce the incidence of immunization. Transfusion refractoriness may also result from an anti-HPA alloim­ munization, although less commonly. Recipient factors associated with platelet refractoriness include fever, splenomegaly, bleeding, DIC, and medications such as amphotericin B. Notably, cold-stored (and cryo­ preserved) PCs have been found to have preserved hemostatic function in acutely bleeding patients despite poor platelet increments. Immunomodulation  Transfusion of allogeneic blood may be associated with immunosuppression, as evidenced early on by the beneficial effect of pretransplant transfusion on kidney graft survival. The intensity of such an effect is debated and, if present, is most prob­ ably attenuated with leukoreduced BCs. Transfusion-related immu­ nomodulation is indeed thought to be mainly mediated by donor leukocytes, whether transfused to the recipient or undergoing apopto­ sis during storage. However, leukoreduced RBCCs or PCs still release immunomodulatory mediators during storage. These mediators, along with the transfused RBCs or platelets, may exert various, possibly opposing, immune effects in vivo, including immunosuppression and inflammation. PART 4 Oncology and Hematology ■ ■NONIMMUNOLOGIC TRANSFUSION ADVERSE REACTIONS Fluid Overload  TACO is a common and underrecognized transfu­ sion adverse reaction. Estimated frequencies vary from ~10 to 100 per 105 BCs. TACO is now the main cause of death from transfusion since the TRALI risk has been mitigated. Risk factors include older age, renal failure, preexisting fluid overload, cardiac dysfunction, administration of a large volume of BCs, and an excessive rate of transfusion in rela­ tion to the patient’s hemodynamic tolerance. TACO results in dyspnea, hypoxia, bilateral and predominantly alveolar infiltrates on chest x-ray, frequent systolic hypertension, and elevated brain natriuretic peptide. Fever may also exist. Prevention involves identifying at-risk patients, close monitoring, a slow transfusion rate (1 RBCC over 3–4 h), and use of diuretics in hemodynamically stable patients with a history of TACO. Treatment requires stopping the transfusion and administrat­ ing oxygen and diuretics. Massive Transfusion-Associated Reactions/Electrolyte and Cold Toxicity Reactions  Reactions related to massive transfu­ sion, i.e., transfusion of 50% of the patient’s total blood volume over 3 h or >5–10 units of RBCCs (plus associated BCs), include citrate toxic­ ity, hypothermia, hyperkalemia, and dilutional coagulopathy. Citrate, which is commonly used to anticoagulate BCs, chelates calcium. Hypo­ calcemia, manifested by circumoral paresthesia, and changes in cardiac function may result from multiple rapid transfusions. Although citrate is quickly metabolized to bicarbonate, calcium infusion (through a separate line) may be required. Rapid transfusion of BCs still at 4°C can result in hypothermia and cardiac dysrhythmias. Use of an inline warmer will prevent this complication. RBC leakage during storage, longer storage, and irradiation increase the concentration of potassium in the unit. Neonates and patients with renal failure or other comor­ bidities (e.g., hyperglycemia or hypocalcemia) are at risk of hyperka­ lemia and resulting acute cardiac toxicity. Treatment includes insulin, glucose, calcium gluconate, and furosemide, and prevention includes the use of washed or plasma-reduced RBCCs or a storage age of <7–10 days and the avoidance of RBCCs stored for >24 h after irradiation. Iron Overload  Each RBCC contains 200–250 mg of iron. In fre­ quently transfused recipients, iron accumulation that is left untreated will affect endocrine, hepatic, and cardiac function. Death may occur from cardiac failure or arrhythmia. Iron overload can be assessed by means of serum ferritin measurements, magnetic resonance imaging, and liver biopsy. Prevention and treatment of this frequently under­ reported transfusion adverse event rely on careful monitoring and iron chelation. Hypotensive Reactions  Acute hypotensive transfusion reactions are defined as an abrupt drop in blood pressure of >30 mmHg early after the start of transfusion and resolving quickly once the transfusion is stopped, without further intervention. Respiratory, gastrointestinal, or mild allergic reactions may also be present. Estimated frequency is 1–10/105 BCs. These reactions may result from the generation of vaso­ active kinins in the BCs and are more likely to occur in hypertensive patients taking angiotensin-converting enzyme (ACE) inhibitors who are therefore less able to metabolize bradykinin. Upon resolution, the same blood product should not be restarted. Switching from an ACE inhibitor to an alternative drug should be considered for patients requiring further transfusions. Adverse Transfusion Reactions of Uncertain Imputability  Necrotizing enterocolitis, which is common in preterm and very-lowbirth-weight neonates, has been infrequently described with close tem­ poral association with RBC transfusion. However, the causality of any association remains to be further ascertained, as does the efficacy of withholding feeds during transfusion to prevent such a complication. Posterior reversible encephalopathy syndrome is a rare syndrome char­ acterized by acute reversible neurologic symptoms related to subcorti­ cal vasogenic brain edema. It has been described within 10 days after RBCC transfusion, mainly in women with severe (and long-standing) anemia. The prognosis is most often favorable, although irreversible neurologic disturbance has been described. Prevention may include avoiding rapid correction of chronic severe anemia. Again, causality remains to be established. ■ ■INFECTIOUS ADVERSE REACTIONS Donor screening involves the selection of healthy donors without highrisk lifestyles, medical conditions, or exposure to transmissible patho­ gens. Tests are performed on donated blood to detect the presence of pathogens by testing for relevant Abs or Ags or by directly detecting infectious agents by nucleic acid amplification. Increasing sensitivity of testing methods has progressively narrowed the “window” period early on after infection during which a low-titer undetectable pathogen may be present in the blood and result in a transfusion-transmitted infection. Transfusion-transmitted bacterial infection remains a significant concern, notably with PCs stored at room temperature, which allows for bacterial proliferation. However, some gram-negative bacteria such as Yersinia can grow at 4°C and therefore may be implicated in infec­ tions related to RBCC transfusion. Recipients of contaminated BCs may develop abrupt (during transfusion and up to several hours after) fever and chills, which can deteriorate to septic shock, DIC, and death. Endotoxin formed within the BC may be implicated. After sampling for bacterial culture, broad-spectrum antibiotics should be promptly initiated. Pathogen reduction of PC and plasma, and perhaps soon of RBCCs as well, offers an additional means of reducing transfusion infection risks. Although effective for a wide range of pathogens, such processes are most often ineffective for bacterial spores and nonenveloped viruses such as hepatitis A virus, parvovirus B19, and hepatitis E virus. Postdonation information (i.e., fever occurring within 24 h after dona­ tion) allows the involved BCs to be quarantined and may provide an additional safety measure. Transfusion-transmitted infections are increasingly rare. However, new or previously unidentified infectious risks may occur, as high­ lighted by the emergence of the transfusion-associated West Nile virus infection and babesiosis in early 2000 in the United States, as well as transfusion-associated hepatitis E in early 2010 in Europe. Such occurrences require active surveillance programs and the appropri­ ate implementation of mitigation measures such as additional test­ ing, pathogen reduction, and travel-related deferral criteria. Along with West Nile virus, a number of other arbovirus-related infections TABLE 118-6  Infectious Transfusion Adverse Events DONATION PREVALENCE (/104 BLOOD DONATIONS) PATHOGEN Bacteria Pyogenic bacteria PC: 10–20 Venipuncture sepsis, diversion of the initial 10–30 mL of blood, bacterial detection, pathogen reduction (for PC) Treponema pallidum (syphilis) ~1a Serologyb,c <0.01 Virus HIV-1/2 ~0.1 Serology, NAT (+/– p24 Ag)b,c 0.1–1d HBV ~0.5 Serology, NATb,c <0.5 (3 without NAT)d HCV 0.2–1.2 Serology, NATb,c <0.1–1d HTLV-1/2 0.05–0.1a Serology, BC leukocyte reduction b,c 0.1–0.3d HEV 0–10 (in endemic regions) NAT Endemic regions: <0.1 with NAT; a transmission rate from infected donors of ~50% has been reported CMV Undetermined Serology, BC leukocyte reductionb,c <0.1 in leukocyte-reduced BCs Parvovirus B19 ~0.5 with viral DNA >106 IU/mL,e up to 100 overall West Nile virus Up to 3 in high season endemic regionsa NATb High season endemic regions: <1 with NAT Parasitef Plasmodium (malaria) ~4 (40–>50 in donors from endemic regions)a Serology (NAT soon available) <0.1 in nonendemic regions Babesia ~90 (in endemic regions)a Serology (NAT implementation underway) Trypanosoma cruzi (Chagas disease) ~0.14 in donors/mothers from endemic regionsa Serology, leukocyte reduction ND aAs assessed based on seropositivity, i.e., including a varying percentage of individuals not harboring the pathogen in their blood. bPrevention measures may also include pathogen reduction (for PC and plasma), cPrevention measures may also include a quarantine of the (cryopreserved) BC pending a negative serology on a subsequent donation (for plasma), dEstimated residual risk. eTransfusion risk deemed as absent below this threshold, fVisceral leishmaniasis is a transfusion risk as well in endemic regions, a risk that may be mitigated by leukocyte reduction. Note. Other pathogens associated with transfusion-transmitted infections at a very low frequency include arboviruses other than West Nile (dengue, Zika virus), hepatitis A, human herpesvirus-8, Japanese encephalitis virus, tick-borne encephalitis virus complex, and the prion responsible for variant Creutzfeldt-Jakob disease (4 cases in the United Kingdom, in the context of the bovine spongiform encephalopathy epidemic, before implementation of systematic leukocyte reduction). Abbreviations: Ag, antigen; BC, blood component; CMV, cytomegalovirus; HBV, hepatitis B virus; HCV, hepatitis C virus; HEV, hepatitis E virus; HTLV, human T-cell leukemia virus; NAT, nucleic acid detection test; ND, not determined; PC platelet concentrate; RBCC, red blood cell concentrate. possibly transmissible by blood transfusion are endemic or involved in epidemic outbreaks. Despite being possibly present in the blood at asymptomatic phases of the disease, documented cases of transfusiontransmitted infections involving these arboviruses have been very rare (Zika), often without a discernible clinical impact (Dengue), or absent (Chikungunya). Route of infection (i.e., intravenous vs mosquito bite), pathogen dose, storage conditions, recipient immune status, and ongo­ ing treatments may all impact the ability of a pathogen in the donor to induce a disease in the recipient. Estimated frequencies of transfusionrelevant infections in donors and of transfusion-transmitted infections are reported in Table 118-6. Such frequencies depend heavily on vari­ ables such as local epidemiology, donor deferral rules, risk reduction measures, and data reporting, and may vary considerably. ALTERNATIVES AND PERSPECTIVES In addition to promoting appropriate transfusion indications, patient blood management programs have highlighted several transfusionsparing strategies, such as the treatment of iron deficiency before surgery and minimization of blood loss. Antifibrinolytic agents such tranexamic acid (TXA) have been shown to be effective in preventing bleeding complications in various forms of hemorrhage. Erythropoi­ etin stimulates erythrocyte production in patients with anemia from chronic renal failure and other conditions. Thrombopoietin recep­ tor agonists may reduce platelet transfusion needs resulting from chemotherapy-induced thrombopenia. Bone marrow transplantation and gene therapy approaches, including CRISPR-Cas9-mediated gene PREVENTION MEASURES (IN ADDITION TO DONOR DEFERRAL) INFECTION PREVALENCE IN RECIPIENTS (/106 BLOOD PRODUCTS TRANSFUSED) Sepsis: PC: 5–30; with bacterial detection: <1 to 10; with pathogen reduction: <1 RBCC: <0.2 NAT Most adults are immune to parvovirus B19; up to 0.12% in seronegative adults has been reported CHAPTER 118 ND (0.04% donors may be within the serology window period) Transfusion Therapy and Biology editing, dramatically reduce the transfusion needs in patients with sickle cell or major thalassemia. Stem cell–derived blood cells such as RBCs or platelets may in the future become a suitable alternative to rare blood donors. Importantly, issues surrounding transfusion safety now fully encom­ pass transfusion efficacy. Linked large-scale databases pertaining to blood donors and transfused patients will also be instrumental in further assessing and understanding the basis of transfusion safety and efficacy. Optimal transfusion care will soon require consideration of new criteria in relation to donor, blood product, and/or recipient characteristics. Acknowledgments The authors are indebted to Jeffery S. Dzieczkowski and Kenneth C. Anderson who co-authored the chapter in a previous edition and expertly paved the way for this chapter. ■ ■FURTHER READING Carson JL et al: Red blood cell transfusion 2023 AABB International guidelines. JAMA 330:1892, 2023. Delaney M et al: Transfusion reactions: Prevention, diagnosis, and treatment. Lancet 388:2825, 2016. Panch SR et al: Hemolytic transfusion reactions. N Engl J Med 381:150, 2019. Stanworth SJ, Shah A: How I use platelet transfusions. Blood 140:1925, 2022. # 49 - 119 Hematopoietic Cell Transplantation ### 119 Hematopoietic Cell Transplantation Frederick R. Appelbaum Hematopoietic Cell Transplantation Bone marrow transplantation was the original term used to describe the collection and transplantation of hematopoietic stem cells, but with the demonstration that peripheral blood and umbilical cord blood are also useful sources of stem cells, hematopoietic cell transplantation has become the preferred generic term for this process. Hematopoietic cell transplantation is used to treat patients with an abnormal but nonmalignant lymphohematopoietic system by replacing it with one from a normal donor. Hematopoietic cell transplantation is also used to treat malignancy by allowing the administration of higher doses of myelosuppressive therapy than would otherwise be possible and, in the setting of allogeneic hematopoietic cell transplantation, by conferring an immunologic graft-versus-tumor effect. The use of hematopoietic cell transplantation is increasing, as it becomes safer and applicable to more diseases and as donor availability expands. The Worldwide Network for Blood and Marrow Transplantation (http://www.wbmt.org) estimates that worldwide more than 100,000 transplants were performed in 2022. The frequency of transplanta­ tion varied widely from country to country, with a close association of transplant rates with gross national income (GNI) per capita. However, even among countries with similar GNIs per capita, there are substan­ tial differences between countries and regions regarding the frequency of transplantation, disease indications, and choice of donor type. PART 4 Oncology and Hematology THE HEMATOPOIETIC STEM CELL Several features of the hematopoietic stem cell (HSC) make trans­ plantation clinically feasible, including its remarkable regenerative capacity, its ability to home to the marrow space following intravenous injection, and the ability of the stem cell to be cryopreserved (Chap. 101). Transplantation of a single stem cell can replace the entire lympho­ hematopoietic system of an adult mouse. In humans, transplantation of a small percentage of a donor’s bone marrow volume regularly results in complete and sustained replacement of the recipient’s entire lymphohematopoietic system, including all red cells, granulocytes, B and T lymphocytes, and platelets, as well as cells comprising the fixed macrophage population, including Kupffer cells of the liver, pulmonary alveolar macrophages, osteoclasts, and Langerhans cells of the skin. Homing of HSCs to their marrow niche initially involves interactions between P- and E-selectins on marrow sinusoidal endothelium with integrins including VLA-4 on HSCs. Once tethered to the vascular endothelium, changes in integrin conformation result in tight adhesion following which stem cells migrate through the endothelium and extra­ cellular matrix eventually reaching the stem cell niche. This last step is facilitated by CXCL12 produced by the niche stroma interacting with the chemokine CXCR4 on HSCs. Human hematopoietic stem cells can survive freezing and thawing with little, if any, damage, making it pos­ sible to remove and store a portion of the patient’s own bone marrow for later reinfusion following treatment of the patient with high dose myelotoxic therapy. CATEGORIES OF HEMATOPOIETIC CELL TRANSPLANTATION Hematopoietic cell transplantation can be described according to the relationship between the patient and the donor and by the anatomic source of stem cells. In ~1% of cases, patients have identical twins who can serve as donors. With the use of syngeneic donors, there is no risk of graft-versus-host disease (GVHD), and unlike the use of autologous mar­ row, there is no risk that the stem cells are contaminated with tumor cells. Allogeneic transplantation involves a donor and a recipient who are not genetically identical. Following allogeneic transplantation, immune cells transplanted with the stem cells or developing from them can react against the patient, causing GVHD. Alternatively, if the immuno­ suppressive preparative regimen used to treat the patient before trans­ plant is inadequate, immunocompetent cells of the patient can cause graft rejection. The risks of these complications are influenced by the degree of matching between donor and recipient for human leukocyte antigen (HLA) molecules encoded by genes of the major histocompat­ ibility complex. HLA molecules are responsible for binding antigenic proteins and presenting them to T cells. The antigens presented by HLA molecules may derive from exogenous sources (e.g., during active infections) or may be endogenous proteins. If individuals are not HLA-matched, T cells from one individual will react strongly to the mismatched HLA, or “major antigens,” of the second. Even if the individuals are HLAmatched, the T cells of the donor may react to differing endogenous or “minor antigens” presented by the HLA of the recipient. Reactions to minor antigens tend to be less vigorous. The genes of major relevance to transplantation include HLA-A, -B, -C, and -D; they are closely linked and therefore tend to be inherited as haplotypes, with only rare crossovers between them. Thus, the odds that any one full sibling will match a patient are one in four, and the probability that the patient has an HLA-identical sibling is 1 − (0.75)n, where n equals the number of siblings. With conventional techniques, the risk of graft rejection is 1–3%, and the risk of severe, life-threatening acute GVHD is ~15% following transplantation between HLA-identical siblings. The incidence of graft rejection and GVHD increases progressively with the use of family member donors mismatched for one, two, or three antigens. Newer approaches to GVHD prophylaxis, including the use of posttransplant high-dose cyclophosphamide, have diminished the impact of HLA mismatching, making transplantation between donor/recipient pairs who share only one HLA haplotype possible. Since the formation of the National Marrow Donor Program and other registries, HLA-matched unrelated donors can be identified for many patients. The genes encoding HLA antigens are highly polymorphic, and thus the odds of any two unrelated individuals being HLA identical are extremely low, somewhat less than 1 in 10,000. However, by recruiting >40 million volunteer donors, HLA-matched donors can be found for ~60% of patients for whom a search is initiated, with higher rates among whites and lower rates among minorities and patients of mixed race. It takes, on average, 3–4 months to complete a search and schedule and initiate an unrelated donor transplant. With improvements in HLA typing and supportive care measures, survival following matched unrelated donor transplantation is essentially the same as that seen with HLA-matched siblings. Allogeneic hematopoietic cell transplantation can be carried out across ABO blood barriers by removing isoagglutinins and/or incom­ patible red blood cells from the donor graft. However, depending on the direction of the mismatch, hemolysis of donor cells by persistent isoagglutinins in the host, or hemolysis of recipient red cells by isoag­ glutinins in the graft or developing from it may occur despite appropri­ ate manipulation of the donor cell product. Autologous transplantation involves the removal and storage of the patient’s own stem cells with subsequent reinfusion after the patient receives high dose myeloablative therapy. Unlike allogeneic transplan­ tation, there is no risk of GVHD or graft rejection with autologous transplantation. On the other hand, autologous transplantation lacks a graft-versus-tumor (GVT) effect, and the autologous stem cell product can be contaminated with tumor cells, which could lead to relapse. A variety of techniques have been developed to “purge” autologous prod­ ucts of tumor cells, but no prospective randomized trials have shown that any approach decreases relapse rates or improves disease-free or overall survival. Bone marrow aspirated from the posterior and anterior iliac crests initially was the source of hematopoietic stem cells for transplantation. Typically, anywhere from 1.5 to 5 × 108 nucleated marrow cells per kilogram are collected for allogeneic transplantation. Several studies have found improved survival following both matched sibling and unrelated transplantation by transplanting higher numbers of bone marrow cells. Hematopoietic stem cells circulate in the peripheral blood but in very low concentrations. Following the administration of a myeloid growth factor such as granulocyte colony-stimulating factor (G-CSF) and during recovery from intensive chemotherapy, the concentration of hematopoietic progenitor cells in blood, as measured either by colony-forming units or expression of the CD34 antigen, increases markedly. This makes it possible to harvest adequate numbers of stem cells from the peripheral blood for transplantation. Donors are typi­ cally treated with 4 or 5 days of hematopoietic growth factor, following which stem cells are collected in one or two 4-h pheresis sessions. In the autologous setting, transplantation of >2.5 × 106 CD34 cells per kilogram, a number that can be collected in most circumstances, leads to rapid and sustained engraftment in virtually all cases. In the 5–10% of patients who fail to mobilize enough CD34+ cells with growth fac­ tor alone, the addition of plerixafor, an antagonist of CXCR4, may be useful. Blocking CXCR4 allows more stem cells to escape the marrow. When compared to the use of autologous marrow, use of periph­ eral blood stem cells results in more rapid hematopoietic recovery. Although this more rapid recovery diminishes the morbidity rate of transplantation, no studies show improved survival. In the setting of allogeneic transplantation, the use of growth factor– mobilized peripheral blood stem cells also results in faster engraftment than seen with marrow but at the cost of more chronic GVHD because of donor T-cell contamination. With matched sibling donors, the increased chronic GVHD is more than balanced by reductions in rates of relapse and nonrelapse mortality, resulting in improved overall sur­ vival. However, in the setting of matched unrelated donor transplanta­ tion, use of peripheral blood results in more chronic GVHD without a compensatory survival advantage. Nonetheless, because of ease of collection, peripheral blood continues to be the more commonly used source of stem cells. Umbilical cord blood contains a high concentration of hematopoietic progenitor cells, allowing for its use as a source of stem cells for trans­ plantation. Cord blood transplantation from family members has been used when the immediate need for transplantation precludes waiting the 9 or so months generally required for the baby to mature to the point of donating marrow. Use of cord blood results in slower peripheral count recovery than seen with marrow but a lower incidence of GVHD, perhaps reflecting the low number of T cells in cord blood. Multiple cord blood banks have been developed to harvest and store cord blood for possible transplantation to unrelated patients from material that would otherwise be discarded. Currently >800,000 units are cryopre­ served and available for use. The advantages of unrelated cord blood are rapid availability and decreased immune reactivity allowing for the use of partially matched units, which is of particular importance for those without matched unrelated donors. The risks of graft failure and trans­ plant-related mortality are related to the dose of cord blood cells per kilogram, which previously limited the application of single cord blood transplantation to pediatric and smaller adult patients. Subsequent trials have found that for patients without suitable single cord units, the use of double cord transplants diminishes the risk of graft failure and early mortality even though only one of the donors ultimately engrafts. Given the similar survival rates seen with cord blood, matched unrelated, and haploidentical family member donors, a source of allogeneic stem cells can now be found for almost every patient in need (Table 119-1). TABLE 119-1  Probability of Identifying a Donor Based on Stem Cell Source and Patient Ethnicity   UNRELATED ADULT % UNRELATED CORD % HAPLOIDENTICAL Ethnicity 8/8a 7/8a ≥4/6b   Caucasian >95 Hispanic Black aMatching for HLA-A, -B, -C, and DRB1. bMatching for HLA-A, -B, and DRB1. THE TRANSPLANT PREPARATIVE REGIMEN The treatment regimen administered to patients immediately preced­ ing transplantation is designed to eradicate the patient’s underlying disease and, in the setting of allogeneic transplantation, immunosup­ press the patient adequately to prevent rejection of the transplanted stem cells. The appropriate regimen therefore depends on the dis­ ease setting and graft source. For example, when transplantation is performed to treat severe combined immunodeficiency and the donor is a histocompatible sibling, no preparative regimen is needed because no host cells require eradication, and the patient is already too immune incompetent to reject the transplanted graft. For aplastic anemia, there is no large population of cells to eradicate, and highdose cyclophosphamide plus antithymocyte globulin are sufficient to immunosuppress the patient adequately to accept the marrow graft. In the setting of thalassemia and sickle cell anemia, high-dose busulfan is frequently added to cyclophosphamide to eradicate hyperplastic host hematopoiesis. A variety of different regimens have been developed to treat malignant diseases. Most regimens include agents with high activity against the tumor in question at conventional doses and with myelosuppression as their predominant dose-limiting toxicity. There­ fore, these regimens commonly include busulfan, cyclophosphamide, melphalan, thiotepa, carmustine, etoposide, and total-body irradiation in various combinations. CHAPTER 119 Although high-dose treatment regimens were the initial approach to transplantation for malignancies, the realization that much of the antitumor effect of transplantation derives from an immunologically mediated GVT response led investigators to ask if reduced-intensity conditioning regimens might be effective and more tolerable. Evidence for a GVT effect comes from studies showing that posttransplant relapse rates are lowest in patients who develop acute and chronic GVHD, higher in those without GVHD, and higher still in recipients of T cell–depleted allogeneic or syngeneic marrow. The demonstration that complete remissions can be obtained in many patients who have relapsed after transplant by simply administering viable lymphocytes from the original donor further strengthens the argument for a potent GVT effect. Accordingly, a variety of alternative regimens have been studied, ranging from nonmyeloablative, which are the very minimum required to achieve engraftment (e.g., fludarabine plus 200 cGy totalbody irradiation) and would cause only transient myelosuppression if no transplant were performed, to so-called reduced-intensity regi­ mens, which would cause significant but not necessarily fatal myelo­ suppression in the absence of transplantation (e.g., fludarabine plus melphalan). With the use of nonmyeloablative and reduced-intensity regimens, engraftment is readily achieved with less toxicity than seen with conventional transplantation. In general, relapse rates are higher following reduced-intensity conditioning, but transplant-related mor­ tality is lower, favoring the use of reduced-intensity conditioning in older patients and those with significant comorbidities. High-dose regimens are favored in those felt able to tolerate the treatment, par­ ticularly if patients have any evidence of measurable disease at the time of transplantation. Hematopoietic Cell Transplantation ■ ■THE TRANSPLANT PROCEDURE Marrow is usually collected from the donor’s posterior and sometimes anterior iliac crests, with the donor under general or spinal anesthesia. Typically, 10–15 mL/kg of marrow is aspirated, placed in heparinized media, and filtered through 0.3- and 0.2-mm screens to remove fat and bony spicules. The collected marrow may undergo further processing depending on the clinical situation, such as the removal of red cells to prevent hemolysis in ABO-incompatible transplants, the removal of donor T cells to prevent GVHD, or attempts to remove possible con­ taminating tumor cells in autologous transplantation. Marrow dona­ tion is safe, with only very rare complications reported. Peripheral blood stem cells are collected by leukapheresis after the donor has been treated with hematopoietic growth factors or, in the setting of autologous transplantation, sometimes after treatment with a combination of chemotherapy and growth factors. Stem cells for transplantation are infused through a large-bore central venous catheter. Such infusions are usually well tolerated, although occasion­ ally patients develop fever, cough, or shortness of breath. These symp­ toms typically resolve with slowing of the infusion. When the stem cell product has been cryopreserved using dimethyl sulfoxide, patients sometimes experience short-lived nausea or vomiting due to the taste (and smell) of the cryoprotectant. ■ ■ENGRAFTMENT AND IMMUNE RECONSTITUTION Peripheral blood counts reach their nadir several days to a week after transplant as a consequence of the preparative regimen; then cells pro­ duced by the transplanted stem cells begin to appear in the peripheral blood. The rate of recovery depends on the source of stem cells and use of posttransplant growth factors. If marrow is the source, recovery to 100 granulocytes/μL occurs on average by day 16 and to 500/μL by day 22. Use of G-CSF–mobilized peripheral blood stem cells speed the rate of recovery by ~1 week compared to marrow, whereas engraftment following cord blood transplantation is typically delayed by ~1 week. Use of a myeloid growth factor after transplant accelerates recovery by 3–5 days. Platelet counts usually recover shortly after granulocytes. While granulocytes and other components of innate immunity recover rapidly after hematopoietic cell transplantation, adaptive immu­ nity, which consists of cellular (T cell) and humoral (B cell) immunity, may take 1–2 years to fully recover. Survival and peripheral expansion of infused donor T cells is the dominant mechanism for T-cell recovery in the first months after hematopoietic cell transplantation and results in mostly CD8+ T cells with a limited repertoire. After several months, de novo generation of donor-derived CD4+ and CD8+ T cells becomes dominant, providing a more diverse T-cell repertoire. B-cell counts recover by 6 months after autologous hematopoietic cell transplantation and 9 months after allogeneic hematopoietic cell transplantation. In gen­ eral, immune recovery occurs more rapidly after autologous than alloge­ neic hematopoietic cell transplantation and after receipt of unmodified grafts compared to the setting of in vivo or ex vivo T-cell depletion. PART 4 Oncology and Hematology Following allogeneic transplantation, engraftment can be docu­ mented using fluorescence in situ hybridization of sex chromosomes if donor and recipient are sex-mismatched or by analysis of short tandem repeat polymorphisms after DNA amplification. ■ ■COMPLICATIONS FOLLOWING HEMATOPOIETIC CELL TRANSPLANTATION Early Direct Chemoradiotoxicities  The transplant preparative regimen may cause a spectrum of acute toxicities that vary according to the intensity of the regimen and the specific agents used but fre­ quently include nausea, vomiting, and mild skin erythema (Fig. 119-1). Pancytopenia Neutropenia Thrombocytopenia Regimen-related toxicities Mucositis SOS Idiopathic pneumonia Graft-vs-host disease Acute GVHD Chronic GVHD Infections Bacterial Fungal Viral Gram positive Gram negative Encapsulated bacteria Candida Aspergillus HSV CMV and adenovirus VZV Day 0 Day 30 Day 60 Day 90 Day 180 Day 360 FIGURE 119-1  Major syndromes complicating marrow transplantation. CMV, cytomegalovirus; GVHD, graft-versus-host disease; HSV, herpes simplex virus; SOS, sinusoidal obstructive syndrome (formerly venoocclusive disease); VZV, varicellazoster virus. The size of the shaded area roughly reflects the period of risk of the complication. High-dose cyclophosphamide can result in hemorrhagic cystitis, which can usually be prevented by bladder irrigation or with the sulfhydryl compound mercaptoethanesulfonate (MESNA). Most high-dose pre­ parative regimens will result in oral mucositis, which typically develops 5–7 days after transplant and often requires narcotic analgesia. Use of a patient-controlled analgesic pump provides the greatest patient satisfac­ tion and results in a lower cumulative dose of narcotic. Keratinocyte growth factor (palifermin) can shorten the duration of mucositis by several days following autologous transplantation. Patients begin losing their hair 5–6 days after transplant and by 1 week are usually profoundly pancytopenic. Depending on the intensity of the conditioning regimen, 3–10% of patients will develop sinusoidal obstruction syndrome (SOS) of the liver (formerly called venoocclusive disease), a syndrome that results from direct cytotoxic injury to hepatic-venular and sinusoidal endo­ thelium, with subsequent deposition of fibrin and the development of a local hypercoagulable state. This chain of events leads to the clinical symptoms of tender hepatomegaly, ascites, jaundice, and fluid reten­ tion. These symptoms can develop any time during the first month after transplant, with the peak incidence at day 16. Predisposing fac­ tors include prior exposure to intensive chemotherapy, pretransplant hepatitis of any cause, and use of more intense conditioning regimens. The mortality rate of sinusoidal obstruction syndrome is ~30%, with progressive hepatic failure culminating in a terminal hepatorenal syndrome. Treatment of severe SOS with defibrotide, a polydeoxyribo­ nucleotide, reduces mortality. Although most pneumonias developing early after transplant are caused by infectious agents, in a small percentage of patients, a diffuse interstitial pneumonia will develop that is a result of direct toxicity of high-dose preparative regimens. Bronchoalveolar lavage usually shows alveolar hemorrhage, and biopsies are typically characterized by diffuse alveolar damage, although some cases may have a more clearly inter­ stitial pattern. High-dose glucocorticoids or anti–tumor necrosis factor therapies are sometimes used as treatment, although randomized trials proving their utility have not been reported. Transplant-associated thrombotic microangiopathy is seen in 5–10% of patients, appearing on average about 1 month after transplant. The syndrome is characterized by presence of schistocytes on peripheral smear, elevated lactate dehydrogenase, thrombocytopenia, and acute kidney injury and is the result of endothelial injury and complement activation. Since calcineurin and mTOR inhibitors are thought to contribute to the pathogenesis of the syndrome, changing immunosup­ pressive regimens is sometimes effective. Patients sometimes respond to eculizumab. Late Direct Chemoradiotoxicities  Two categories of chronic pulmonary disease occur in patients >3 months after hematopoietic cell transplantation. Cryptogenic organizing pneumonia is a restrictive lung disease characterized by dry cough, shortness of breath, and chest imaging showing a diffuse, fluffy infiltrate. Biopsy shows granula­ tion tissue within alveolar spaces and small airways and no infectious agents. The disease responds well to corticosteroids and is entirely reversible. Bronchiolitis obliterans is an obstructive disease presenting with cough, progressive dyspnea, and radiologic evidence of air trap­ ping. Pathology shows collagen and granulation tissue in and around bronchial structures and eventually obliteration of small airways. The disease is usually associated with chronic GVHD, and although it may respond to increasing immunosuppression, complete reversal is uncommon. Other late complications of the preparative regimen include decreased growth velocity in children and delayed development of secondary sex characteristics. These complications can be partly ameliorated with the use of appropriate growth and sex hormone replacement. Most men become azoospermic, and most postpubertal women will develop ovarian failure, which should be treated. However, pregnancy is possible after transplantation, and patients should be counseled accordingly. Thyroid dysfunction, usually well compen­ sated, is sometimes seen. Cataracts develop in 10–20% of patients and are most common in patients treated with total-body irradiation and those who receive glucocorticoid therapy after transplant for treat­ ment of GVHD. Aseptic necrosis of the femoral head is seen in 10% of patients and is particularly frequent following chronic glucocorticoid therapy. Both acute and late chemoradiotoxicities (except those due to glucocorticoids and other agents used to treat GVHD) are less frequent in recipients of reduced-intensity compared to high-dose preparative regimens. Graft Failure  Although complete and sustained engraftment is usually seen after transplant, occasionally marrow function either does not return or, after a brief period of engraftment, is lost. Graft failure after autologous transplantation can be the result of inadequate num­ bers of stem cells being transplanted, damage during ex vivo treatment or storage, or exposure of the patient to myelotoxic agents after trans­ plant. Infections with cytomegalovirus (CMV) or human herpesvirus type 6 have also been associated with loss of marrow function. Graft failure after allogeneic transplantation can also be due to immunologic rejection of the graft by immunocompetent host cells. Such rejection is generally thought to be mostly T-cell–mediated, but the presence before hematopoietic cell transplantation of donor-specific HLA anti­ bodies in the patient is associated with poor engraftment, leading to the recommendation for screening for donor-directed anti-HLA anti­ bodies in recipients prior to transplant. Immunologically based graft rejection is more common following use of less immunosuppressive preparative regimens, in recipients of T-cell–depleted stem cell prod­ ucts, and in patients receiving grafts from HLA-mismatched donors or cord blood. Treatment of graft failure involves removing all potentially myelo­ toxic agents from the patient’s regimen and attempting a short trial of a myeloid growth factor. Persistence of lymphocytes of host origin in allogeneic transplant recipients with graft failure indicates immu­ nologic rejection. Reinfusion of donor stem cells in such patients is usually unsuccessful unless preceded by a second immunosuppressive preparative regimen. Standard high-dose preparative regimens are tolerated poorly if administered within 100 days of a first transplant because of cumulative toxicities. However, reduced-intensity condi­ tioning regimens have been effective in some cases. Graft-Versus-Host Disease  Acute GVHD occurs within the first 3 months after allogeneic transplant with a peak onset around 4 weeks and is characterized by an erythematous maculopapular rash; by persistent anorexia or diarrhea, or both; and by liver disease with increased serum levels of bilirubin, alanine and aspartate aminotrans­ ferase, and alkaline phosphatase. Because many conditions can mimic acute GVHD, the diagnosis usually requires skin, liver, or endoscopic biopsy for confirmation. In all these organs, endothelial damage and lymphocytic infiltrates are seen. In skin, the epidermis and hair follicles are damaged; in liver, the small bile ducts show segmental disruption; and in intestines, destruction of the crypts and mucosal ulceration may be noted. A commonly used rating system for acute GVHD is shown in Table 119-2. Grade I acute GVHD is of little clinical significance, does not affect the likelihood of survival, and does not require treat­ ment. In contrast, grades II to IV GVHD are associated with significant symptoms and a poorer probability of survival and require aggressive TABLE 119-2  Clinical Staging and Grading of Acute Graft-Versus-Host Disease CLINICAL STAGE SKIN LIVER—BILIRUBIN, kmol/L (mg/dL) GUT Rash <25% body surface 34–51 (2–3) Diarrhea 500–1000 mL/d Rash 25–50% body surface 51–103 (3–6) Diarrhea 1000–1500 mL/d Generalized erythroderma 103–257 (6–15) Diarrhea >1500 mL/d Desquamation and bullae >257 (>15) Ileus OVERALL CLINICAL GRADE SKIN STAGE LIVER STAGE GUT STAGE I 1–2 II 1–3 III 1–3 2–3 2–3 IV 2–4 2–4 2–4 therapy. The incidence of acute GVHD is higher in recipients of stem cells from mismatched or unrelated donors, in older patients, and in patients unable to receive full doses of drugs used to prevent the disease. Historically, the standard approach to GVHD prevention was the administration of a calcineurin inhibitor (cyclosporine or tacrolimus) paired with an antimetabolite (most commonly methotrexate) follow­ ing transplantation. Prospective randomized trials have demonstrated the benefit of adding a third drug, either mycophenolate mofetil, abata­ cept, or posttransplant cyclophosphamide, to the two-drug regimen. Other approaches include the addition of anti–T-cell immune globulin (ATG) to the GVHD prophylactic regimen or the removal of subsets or all T cells from the stem cell inoculum. Despite prophylaxis, significant acute GVHD will develop in ~30% of recipients of stem cells from matched siblings. Factors associated with a greater risk of acute GVHD include HLA-mismatching between recipient and donor, patient and donor age, use of more intense pre­ parative regimens, and use of multiparous women as donors. Presum­ ably, multiparous women have more alloreactivity based on carriage of genetically disparate fetuses. Disruption of the intestinal microbiota leading to loss of diversity and overgrowth by a single taxon is associ­ ated with a higher risk of GVHD and transplant-associated mortality. Biomarkers, including ST2, REG32, and TNF R1, have been identified that predict the severity of acute GVHD. The disease is usually treated with prednisone at a daily dose of 1–2 mg/kg. Patients in whom the acute GVHD fails to respond to prednisone sometimes respond to the oral JAK2 inhibitor ruxolitinib. CHAPTER 119 Chronic GVHD occurs most commonly between 3 months and 2 years after allogeneic transplant, developing in 20–50% of recipients. The disease is more common in older patients, with the use of periph­ eral blood rather than marrow as the stem cell source, in recipients of mismatched or unrelated stem cells, and in those with a preceding epi­ sode of acute GVHD. The disease resembles an autoimmune disorder with malar rash, sicca syndrome, arthritis, obliterative bronchiolitis, and bile duct degeneration with cholestasis. Mild chronic GVHD can sometimes be managed using local therapies (topical glucocorticoids to skin and cyclosporine eye drops). More severe disease requires systemic therapy usually with prednisone, which leads to responses in 40–60% of patients. Three drugs have received U.S. Food and Drug Administration approval for the treatment of steroid-resistant chronic GVHD: ibrutinib, ruxolitinib, and belumosudil. All three are kinase inhibitors, a class of compounds that reduces growth signals and activation of key cellular proteins involved with cell activation, migra­ tion, and proliferation. Mortality rates from chronic GVHD average around 15% but range from 5 to 50% depending on severity. In most patients, chronic GVHD resolves, but it may require 1–3 years of immunosuppressive treatment before these agents can be withdrawn without the disease recurring. Because patients with chronic GVHD are susceptible to significant infection, they should receive prophylactic trimethoprim-sulfamethoxazole, and all suspected infections should be investigated and treated aggressively. Hematopoietic Cell Transplantation Although onset before or after 3 months after transplant is often used to discriminate between acute and chronic GVHD, occasional patients will develop signs and symptoms of acute GVHD after 3 months (late-onset acute GVHD), whereas others will exhibit signs and symp­ toms of both acute and chronic GVHD (overlap syndrome). No data suggest that these patients should be treated differently than those with classic acute or chronic GVHD. From 3 to 5% of patients will develop an autoimmune disorder following allogeneic hematopoietic cell transplantation, most com­ monly autoimmune hemolytic anemia or idiopathic thrombocyto­ penic purpura. Unrelated donor source and chronic GVHD are risk factors, but autoimmune disorders have been reported in patients with no obvious GVHD. Treatment is with prednisone, cyclosporine, or rituximab. Infection  Posttransplant patients, particularly recipients of allo­ geneic transplantation, require unique approaches to the problem of infection. Early after transplantation, patients are profoundly neutro­ penic, and because the risk of bacterial infection is so great, most cen­ ters place patients on broad-spectrum antibiotics once the granulocyte count falls to <500/μL. Prophylaxis against fungal infections reduces rates of infection and improves overall survival. Fluconazole is often used for patients with standard risk, while prophylaxis with mold active agents (voriconazole, posaconazole, or isavuconazonium) should be considered for patients at higher risk, such as those with a prior fun­ gal infection. Patients seropositive for herpes simplex should receive acyclovir or valacyclovir prophylaxis. One approach to infection pro­ phylaxis is shown in Table 119-3. Despite these prophylactic measures, most patients will develop fever and signs of infection after transplant. The management of patients who become febrile despite bacterial and fungal prophylaxis is a difficult challenge and is guided by individual aspects of the patient and by the institution’s experience. PART 4 Oncology and Hematology The general problem of infection in the immunocompromised host is discussed in Chap. 148. Once patients engraft, the incidence of bacterial infection dimin­ ishes; however, patients, particularly allogeneic transplant recipients, remain at significant risk of infection. During the period from engraft­ ment until about 3 months after transplant, the most common causes of infection are gram-positive bacteria, fungi (particularly Aspergillus), and viruses including CMV. CMV disease, which in the past was fre­ quently seen and often fatal, can be prevented in seronegative patients transplanted from seronegative donors using either seronegative blood products or products from which the white blood cells have been removed. In seropositive patients or patients transplanted from seropositive donors, either prophylaxis or preemptive therapy is used. Letermovir administered over the first 3 months after transplant is effective as prophylaxis. An alternative approach is to monitor blood of patients after transplant using polymerase chain reaction assays for viral DNA and to treat reactivation preemptively with ganciclovir before clinical disease develops. Foscarnet is effective for some patients who develop CMV antigenemia or infection despite the use of ganci­ clovir or who cannot tolerate the drug, but it can be associated with severe electrolyte wasting. TABLE 119-3  Approach to Infection Prophylaxis in Allogeneic Transplant Recipients ORGANISM AGENT APPROACH Bacterial Levofloxacin 750 mg PO or IV daily Fungal Fluconazole 400 mg PO qd to day 75 posttransplant Pneumocystis jirovecii Trimethoprimsulfamethoxazole 1 double-strength tablet PO bid 2 days/week until day 180 or off immunosuppression Viral     Herpes simplex Acyclovir 800 mg PO bid to day 30 Varicella-zoster Acyclovir 800 mg PO bid to day 365 Cytomegalovirus Ganciclovir 5 mg/kg IV bid for 7 days, then 5 (mg/kg)/d 5 days/week to day 100 Pneumocystis jirovecii pneumonia, once seen in 5–10% of patients, can be prevented by treating patients with oral trimethoprim-sulfa­ methoxazole for 1 week before transplant and resuming the treatment once patients engraft. Respiratory viruses that cause community-acquired infections, including respiratory syncytial virus (RSV), parainfluenza virus, influ­ enza virus, and metapneumovirus, can be life threatening or fatal in the posttransplant patient. Protection of patients from infected visitors and staff by avoiding such contacts is critical. Neuraminidase inhibi­ tors are effective for influenza infections. Oral or inhaled ribavirin is sometimes used for RSV. The risk of infection diminishes considerably beyond 3 months after transplant unless chronic GVHD requiring continuous immu­ nosuppression develops. Most transplant centers recommend continu­ ing trimethoprim-sulfamethoxazole prophylaxis while patients are receiving any immunosuppressive drugs and also recommend careful monitoring for late CMV reactivation. In addition, many centers rec­ ommend prophylaxis against varicella-zoster, using acyclovir for 1 year after transplant. Antibody titers to vaccine-preventable diseases (e.g., tetanus, polio, mumps, rubella, and encapsulated organisms) decline after allogeneic or autologous transplantation if the recipient is not revaccinated. Vaccination begins at 3 months after transplantation for SAR-CoV-2 and 6 months for influenza (or 3–4 months when seasonal prevalence is high). Other nonlive routine childhood vaccinations should be repeated, usually starting at 12 months after transplantation. Live vaccines (measles, mumps, and rubella [MMR] or MMR plus varicella [MMR-V]) are generally not administered before 2 years after hematopoietic cell transplantation. TREATMENT Nonmalignant Diseases Evidence-based indications for hematopoietic cell transplantation have been published by several organizations and are guided not only by disease-related factors but also by patient comorbidities, socioeconomic issues, caregiver and donor availability, and patient preference. IMMUNODEFICIENCY DISORDERS By replacing abnormal stem cells with cells from a normal donor, hematopoietic cell transplantation can cure patients of a variety of immunodeficiency disorders including severe combined immu­ nodeficiency, Wiskott-Aldrich syndrome, and Chédiak-Higashi syndrome. The widest experience is with severe combined immu­ nodeficiency disease, where cure rates of >90% can be expected with allogeneic transplantation from a suitable related or unrelated donor when carried out shortly after birth (Table 119-4). Treatment of severe refractory autoimmune diseases with hematopoietic stem cell transplantation is also beginning to be explored (see below). APLASTIC ANEMIA Transplantation from matched siblings after a preparative regimen of high-dose cyclophosphamide and antithymocyte globulin cures >95% of patients age <40 years with severe aplastic anemia. Histori­ cally, results in older patients and in recipients of mismatched fam­ ily member or unrelated marrow were less favorable, and therefore, a trial of immunosuppressive therapy was recommended for such patients before considering transplantation. However, results with transplantation have improved leading many to recommend trans­ plantation as initial therapy. Transplantation is effective in all forms of aplastic anemia including, for example, the syndromes associated with paroxysmal nocturnal hemoglobinuria and Fanconi’s anemia. Patients with Fanconi’s anemia are abnormally sensitive to the toxic effects of alkylating agents, and so less intensive preparative regi­ mens are used in their treatment (Chap. 107). HEMOGLOBINOPATHIES Marrow transplantation from an HLA-identical sibling following a preparative regimen of busulfan and cyclophosphamide can cure TABLE 119-4  Estimated 3-Year Survival Rates Following Transplantationa DISEASE ALLOGENEIC, % AUTOLOGOUS, % Severe combined immunodeficiency NA Aplastic anemia NA Thalassemia NA Acute myeloid leukemia       First remission ID   Second remission ID Acute lymphocytic leukemia       First remission ID   Second remission ID Chronic myeloid leukemia       Chronic phase NA   Accelerated phase NA   Blast crisis NA Chronic lymphocytic leukemia NA Myelodysplasia NA Multiple myeloma—initial therapy NA Non-Hodgkin’s lymphoma       First relapse/second remission Hodgkin’s disease       First relapse/second remission aThese estimates are mostly based on results of transplants performed between 2010 and 2020 reported by the Center for International Blood and Marrow Transplant Research (CIBMTR). The analysis has not been reviewed by their Advisory Committee. Abbreviations: ID, insufficient data; NA, not applicable. 80–90% of patients with thalassemia major. The best outcomes can be expected if patients are transplanted before they develop hepa­ tomegaly or portal fibrosis and if they have been given adequate iron chelation therapy. Among such patients, the probabilities of 5-year survival and disease-free survival are 95 and 90%, respec­ tively. Although prolonged survival can be achieved with aggressive chelation therapy, transplantation is the only curative treatment for thalassemia. Transplantation is potentially curative for patients with sickle cell anemia. Two-year survival and disease-free survival rates of 95 and 85%, respectively, have been reported following matched sibling or cord blood transplantation. Decisions about patient selec­ tion and the timing of transplantation remain difficult, but trans­ plantation is a reasonable option for children and young adults who have suffered complications of sickle cell anemia including stroke, recurrent vasoocclusive pain, sickle cell lung disease, or sickle nephropathy (Chap. 103). As new gene therapies become available, the indications for allogeneic hematopoietic cell transplantation for thalassemia and sickle cell disease may change. OTHER NONMALIGNANT DISEASES Theoretically, hematopoietic cell transplantation should be able to cure any disease that results from an inborn error of the lymphohe­ matopoietic system. Transplantation has been used successfully to treat congenital disorders of white blood cells such as Kostmann’s syndrome, chronic granulomatous disease, and leukocyte adhesion deficiency. Congenital anemias such as Blackfan-Diamond anemia can also be cured with transplantation. Since the penetrance of some congenital marrow failure states is variable, potential family member donors should be carefully screened before use to assure they are not affected. Infantile malignant osteopetrosis is due to an inability of the osteoclast to resorb bone, and because osteoclasts derive from the marrow, transplantation can cure this rare inherited disorder. Hematopoietic cell transplantation has been used as treatment for several storage diseases caused by enzymatic deficiencies, such as Gaucher’s disease, Hurler’s syndrome, Hunter’s syndrome, and infantile metachromatic leukodystrophy. Transplantation for these diseases has not been uniformly successful, but treatment early in the course of these diseases, before irreversible damage to extra­ medullary organs has occurred, increases the chance for success. Transplantation is being applied as a treatment for severe acquired autoimmune disorders. These approaches are based on studies demonstrating that transplantation can reverse autoimmune disorders in animal models and on the observation that occasional patients with coexisting autoimmune disorders and hematologic malignancies have been cured of both with transplantation. A prospective randomized trial found that patients with severe sclero­ derma have improved event-free and overall survival if treated with hematopoietic cell transplantation. Randomized studies are explor­ ing a similar approach for patients with multiple sclerosis. ACUTE LEUKEMIA Allogeneic hematopoietic cell transplantation cures ~30% of patients who do not achieve a complete response after induction chemotherapy for acute myeloid leukemia (AML) and is the only form of therapy that can cure such patients. Thus, all patients with AML who are possible transplant candidates should have their HLA type determined soon after diagnosis to enable hematopoietic cell transplantation for those who fail to enter remission. Cure rates of 45–50% are seen when patients are transplanted in sec­ ond remission or in first relapse. The best results with allogeneic transplantation are achieved when applied during first remission, with long-term disease-free survival rates averaging 55–60%. Metaanalyses of studies comparing matched related donor transplanta­ tion to chemotherapy for adult AML patients age <60 years show a survival advantage with transplantation. This advantage is greatest for those with adverse and intermediate-risk disease but is not seen in patients with favorable-risk AML. Some centers rely on measure­ ments of minimal residual disease (MRD) as determined by either multidimensional flow cytometry or molecular methods to further define transplant candidacy, proceeding with transplantation in otherwise favorable risk patients if MRD positive and withholding transplantation in MRD-negative intermediate-risk patients. While hematopoietic cell transplantation can be performed in patients up to age 80, prospective trials comparing hematopoietic cell trans­ plantation with chemotherapy are lacking for older patients. Autol­ ogous transplantation has no defined role in the treatment of AML. CHAPTER 119 Hematopoietic Cell Transplantation Similar to patients with AML, adults with acute lymphocytic leukemia who do not achieve a complete response to induction chemotherapy can be cured in ~30% of cases with immediate transplantation. Cure rates improve to 40–50% in second remis­ sion, and therefore, transplantation can be recommended for adults who have persistent disease after induction chemotherapy or who subsequently relapse. Transplant outcomes in second remission are improved if carried out when MRD assessments are negative, and so use of agents such as blinatumomab to achieve an MRD-negative state before transplantation is recommended. Transplantation in first remission results in cure rates of about 65%. Transplanta­ tion appears to offer a survival advantage over chemotherapy for patients with high-risk disease as defined by molecular profiling. Debate continues about whether adults with standard-risk disease should be transplanted in first remission or whether transplanta­ tion should be reserved until relapse. Autologous transplantation is associated with a higher relapse rate but a somewhat lower risk of nonrelapse mortality when compared to allogeneic transplanta­ tion. Autologous transplantation has no obvious role in treatment for acute lymphocytic leukemia in first remission, and for secondremission patients, most experts recommend use of allogeneic stem cells if an appropriate donor is available. CHRONIC LEUKEMIA Allogeneic hematopoietic cell transplantation is indicated for patients with chronic myeloid leukemia (CML) who are in chronic phase but have failed therapy with two or more tyrosine kinase inhibitors. In such patients, cure rates of 70% can be expected. Hematopoietic cell transplantation is also recommended for patients with CML who present or progress to accelerated phase or blast crisis, although lower cure rates are seen in such patients (Chap. 110). Although allogeneic transplantation can cure patients with chronic lymphocytic leukemia (CLL), it has not been extensively studied because of the chronic nature of the disease, the age profile of patients, and more recently, the availability of multiple effective therapies. In those cases where it was studied, complete remissions were achieved in the majority of patients, with disease-free survival rates of ~65% at 3 years, despite the advanced stage of the disease at the time of transplant. MYELODYSPLASIA AND MYELOPROLIFERATIVE DISORDERS Between 40 and 65% of patients with myelodysplasia can be cured with allogeneic transplantation. Results are better among younger patients and those with less advanced disease. However, patients with early-stage myelodysplasia can live for extended periods with­ out intervention, and so transplantation is generally reserved for patients with an International Prognostic Scoring System (IPSS) score of Int-2 or higher, or for selected patients with an IPSS score of Int-1 who have other poor prognostic features (Chap. 107). Allo­ geneic hematopoietic cell transplantation can cure patients with primary myelofibrosis or myelofibrosis secondary to polycythemia vera or essential thrombocythemia, with 5-year progression-free survival rates in excess of 65% being reported. It may require many months for the fibrosis to resolve. LYMPHOMA Patients with disseminated intermediate- or high-grade non-Hodgkin’s lymphoma who have not been cured by first-line chemotherapy and are transplanted in first relapse or second remission can still be cured in 50–60% of cases. This represents a clear advantage over results obtained with conventional-dose salvage chemotherapy. It is unsettled whether patients with high-risk disease benefit from transplantation in first remission. Most experts favor the use of autologous rather than allogeneic transplantation for patients with intermediate- or high-grade non-Hodgkin’s lymphoma, because fewer complications occur with this approach and survival appears equivalent. The use of chimeric antigen receptor T cells targeting CD19 has been reported to yield results similar to those achieved with autologous stem cell transplantation. As yet, no consensus has been reached about how to sequence these two therapies. Although autologous transplantation results in high response rates in patients with recurrent disseminated indolent non-Hodgkin’s lymphoma, the availability of newer agents for this category of patient leaves the role of transplantation unsettled. Reduced-intensity condition­ ing regimens followed by allogeneic transplantation result in high rates of complete and enduring complete responses in patients with recurrent indolent lymphomas. PART 4 Oncology and Hematology The role of transplantation in Hodgkin’s lymphoma is similar to that in intermediate- and high-grade non-Hodgkin’s lymphoma. With transplantation, 3-year disease-free survival is 40–50% in patients who never achieved a first remission with standard chemo­ therapy and up to 80% for those transplanted in second remission. Transplantation has no defined role in first remission in Hodgkin’s lymphoma. MYELOMA Patients with myeloma whose disease progresses after first-line therapy can sometimes benefit from allogeneic or autologous trans­ plantation. Prospective randomized studies demonstrate that the inclusion of autologous transplantation as part of initial ther­ apy results in improved disease-free survival and overall survival. Further benefit is seen with the use of lenalidomide mainte­ nance therapy following transplantation. The use of autologous transplantation followed by nonmyeloablative allogeneic transplan­ tation has yielded mixed results. SOLID TUMORS Patients with testicular cancer in whom first-line platinum-containing chemotherapy has failed can still be cured in ~50% of cases if treated with high-dose chemotherapy with autologous stem cell support, an outcome better than that seen with low-dose salvage chemotherapy. The use of high-dose chemotherapy with autologous stem cell support is being studied for several other solid tumors, including neuroblastoma and pediatric sarcomas. As in most other settings, the best results were obtained in patients with limited amounts of disease and in whom the remaining tumor remains sen­ sitive to conventional-dose chemotherapy. Few randomized trials of transplantation in these diseases have been completed. POSTTRANSPLANT RELAPSE Patients who relapse following autologous transplantation some­ times respond to further chemotherapy and may be candidates for possible allogeneic transplantation, particularly if the remis­ sion following the initial autologous transplant was long. Several options are available for patients who relapse following allogeneic transplantation. Treatment with infusions of unirradiated donor lymphocytes results in complete responses in as many as 75% of patients with chronic myeloid leukemia, 40% with myelodysplasia, 25% with AML, and 15% with myeloma. Major complications of donor lymphocyte infusions include transient myelosuppression and the development of GVHD. These complications depend on the number of donor lymphocytes given and the schedule of infusions, with less GVHD seen with lower dose, fractionated schedules. ■ ■FURTHER READING Dadwal SS et al: How I prevent viral reactivation in high-risk patients. Blood 141:2062, 2023. DeFilipp Z et al: Hematopoietic cell transplantation in the treatment of adult acute lymphoblastic leukemia: Updated 2019 evidence-based review from the American Society for Transplantation and Cellular Therapy. Biol Blood Marrow Transplant 25:2113, 2019. Duarte RF et al: Indications for haematopoietic stem cell transplanta­ tion for haematological diseases, solid tumours and immune disor­ ders: current practice in Europe, 2019. Bone Marrow Transplantation 54:1525, 2019. Jamy O et al: Novel developments in the prophylaxis and treatment of acute GVHD. Blood 142:1037, 2023. McDonald GB et al: Survival, nonrelapse mortality, and relapserelated mortality after allogeneic hematopoietic cell transplantation: Comparing 2003-2007 versus 2013-2017 cohorts. Ann Intern Med 172:229, 2020. Miller PDE et al: Joint consensus statement on the vaccination of adult and paediatric haematopoietic stem cell transplant recipients: Prepared on behalf of the British Society of Blood and Marrow Trans­ plantation and Cellular Therapy (BSBMTCT), the Children’s Cancer and Leukaemia Group (CCLG), and British Infection Association (BIA). J Infect 86:1, 2023. Niederwieser D et al: One and a half million hematopoietc stem cell transplants: Continuous and differential improvement in worldwide access with the use of non-identical family donors. Haematologica 107:1045, 2022. Scott BL et al: Myeloablative versus reduced-intensity conditioning for hematopoietic cell transplantation in acute myelogenous leuke­ mia and myelodysplastic syndromes: Long-term follow-up of the BMT CTN 0901 clinical trial. Transplant Cell Ther 27:483, 2021. Westin J, Sehn LH: CAR T cells as a second-line therapy for large B-cell lymphoma: A paradigm shift? Blood 139:2737, 2022. Zeiser R, Lee SJ: Three Food and Drug Administration-approved therapies for chronic GVHD. Blood 139:1642, 2022. # 50 - SECTION 3 Disorders of Hemostasis ## SECTION 3 Disorders of Hemostasis Section 3 Disorders of Hemostasis Barbara A. Konkle Disorders of Platelets and Vessel Wall Hemostasis is a dynamic process in which the platelet and the blood vessel wall play key roles. Platelets are activated upon adhesion to von Willebrand factor (VWF) and collagen in the exposed subendothelium after injury. Platelet activation is also mediated through shear forces imposed by blood flow itself, particularly in areas where the vessel wall is diseased, and is also affected by the inflammatory state of the endo­ thelium. The activated platelet surface provides the major physiologic site for coagulation factor activation, which results in further platelet activation and fibrin formation. Genetic and acquired influences on the platelet and vessel wall, as well as on the coagulation and fibrino­ lytic systems, determine whether normal hemostasis or bleeding or clotting symptoms will result. THE PLATELET Platelets are released from the megakaryocyte, likely under the influ­ ence of flow in the capillary sinuses. The normal blood platelet count is 150,000–450,000/μL. The major regulator of platelet production is the hormone thrombopoietin (TPO), which is synthesized in the liver and other organs. Synthesis is increased with inflammation and specifically by interleukin 6. TPO binds to its receptor on platelets and megakaryo­ cytes, by which it is removed from the circulation. Thus, a reduction in platelet and megakaryocyte mass increases the level of TPO, which then stimulates platelet production. Platelets circulate with an average life span of 7–10 days. Approximately one-third of the platelets reside in the spleen, and this number increases in proportion to splenic size, although the platelet count rarely decreases to <40,000/μL as the spleen enlarges. Platelets are physiologically very active, but are anucleate, and thus have limited capacity to synthesize new proteins. Normal vascular endothelium contributes to preventing thrombosis by inhibiting platelet function (Chap. 69). When vascular endothelium is injured, these inhibitory effects are overcome, and platelets adhere to the exposed intimal surface primarily through VWF, a large multi­ meric protein present in both plasma and in the extracellular matrix of the subendothelial vessel wall. Platelet adhesion results in the genera­ tion of intracellular signals that lead to activation of the platelet glyco­ protein (Gp) IIb/IIIa (αIIbβ3) receptor and resultant platelet aggregation. Activated platelets undergo release of their granule contents, which include nucleotides, adhesive proteins, growth factors, and procoagu­ lants that serve to promote platelet aggregation and blood clot forma­ tion and influence the environment of the forming clot. During platelet aggregation, additional platelets are recruited to the site of injury, leading to the formation of an occlusive platelet thrombus. The platelet plug is stabilized by the fibrin mesh that develops simultaneously as the product of the coagulation cascade. THE VESSEL WALL Endothelial cells line the surface of the entire circulatory tree, totaling 1–6 × 1013 cells, enough to cover a surface area equivalent to about six tennis courts. The endothelium is physiologically active, control­ ling vascular permeability, flow of biologically active molecules and nutrients, blood cell interactions with the vessel wall, the inflammatory response, and angiogenesis. The endothelium normally presents an antithrombotic surface (Chap. 69) but rapidly becomes prothrombotic when stimulated, which promotes coagulation, inhibits fibrinolysis, and activates plate­ lets. In many cases, endothelium-derived vasodilators are also platelet inhibitors (e.g., nitric oxide), and conversely, endothelium-derived vasoconstrictors (e.g., endothelin) can also be platelet activators. The net effect of vasodilation and inhibition of platelet function is to promote blood fluidity, whereas the net effect of vasoconstriction and platelet activation is to promote thrombosis. Thus, blood fluidity and hemostasis are regulated by the balance of antithrombotic/prothrom­ botic and vasodilatory/vasoconstrictor properties of endothelial cells. DISORDERS OF PLATELETS ■ ■THROMBOCYTOPENIA Thrombocytopenia results from one or more of three processes: (1) decreased bone marrow production; (2) sequestration, usually in an enlarged spleen; and/or (3) increased platelet destruction. Disorders of production may be either inherited or acquired. In evaluating a patient with thrombocytopenia, a key step is to review the peripheral blood smear and to first rule out “pseudothrombocytopenia,” particularly in a patient without an apparent cause for the thrombocytopenia. Pseu­ dothrombocytopenia (Fig. 120-1B) is an in vitro artifact resulting from platelet agglutination via antibodies (usually IgG, but also IgM and IgA) when the calcium content is decreased by blood collection in eth­ ylenediamine tetraacetic (EDTA) (the anticoagulant present in tubes [purple top] used to collect blood for complete blood counts [CBCs]). If a low platelet count is obtained in EDTA-anticoagulated blood, a blood smear should be evaluated and a platelet count determined in blood collected into sodium citrate (blue top tube) or heparin (green top tube), or a smear of freshly obtained unanticoagulated blood, such as from a finger stick, can be examined. CHAPTER 120 Disorders of Platelets and Vessel Wall APPROACH TO THE PATIENT Thrombocytopenia The history and physical examination, results of the CBC, and review of the peripheral blood smear are all critical components in the initial evaluation of thrombocytopenic patients (Fig. 120-2). The overall health of the patient and whether they are receiving drug treatment will influence the differential diagnosis. A healthy young adult with thrombocytopenia will have a much more lim­ ited differential diagnosis than an ill hospitalized patient who is receiving multiple medications. Except in less common inherited disorders, decreased platelet production usually results from bone marrow disorders that also affect red blood cell (RBC) and/or white blood cell (WBC) production. Because myelodysplasia can present with isolated thrombocytopenia, the bone marrow should be exam­ ined in patients presenting with isolated thrombocytopenia who are older than 60 years of age or who do not respond to initial therapy. While inherited thrombocytopenia is uncommon, any prior platelet counts should be retrieved and a family history regarding thrombo­ cytopenia obtained. A careful history of drug ingestion should be obtained, including nonprescription and herbal remedies, because drugs are the most common cause of thrombocytopenia. The physical examination can document an enlarged spleen, evidence of chronic liver disease, and other underlying disorders. Mild to moderate splenomegaly may be difficult to appreciate in many individuals due to body habitus and/or obesity but can be eas­ ily assessed by abdominal ultrasound. A platelet count of approxi­ mately 5000–10,000 is required to maintain vascular integrity in the microcirculation. When the count is markedly decreased, petechiae first appear in areas of increased venous pressure, the ankles and feet in an ambulatory patient. Petechiae are pinpoint, nonblanching hemorrhages and are usually a sign of a decreased platelet num­ ber and not platelet dysfunction. Wet purpura, blood blisters that form on the oral mucosa, are thought to denote an increased risk of life-threatening hemorrhage in the thrombocytopenic patient. Excessive bruising is seen in disorders of both platelet number and function. Infection-Induced Thrombocytopenia  Many viral and bacte­ rial infections result in thrombocytopenia and are the most common # 51 - 120 Disorders of Platelets and Vessel Wall ### 120 Disorders of Platelets and Vessel Wall Section 3 Disorders of Hemostasis Barbara A. Konkle Disorders of Platelets and Vessel Wall Hemostasis is a dynamic process in which the platelet and the blood vessel wall play key roles. Platelets are activated upon adhesion to von Willebrand factor (VWF) and collagen in the exposed subendothelium after injury. Platelet activation is also mediated through shear forces imposed by blood flow itself, particularly in areas where the vessel wall is diseased, and is also affected by the inflammatory state of the endo­ thelium. The activated platelet surface provides the major physiologic site for coagulation factor activation, which results in further platelet activation and fibrin formation. Genetic and acquired influences on the platelet and vessel wall, as well as on the coagulation and fibrino­ lytic systems, determine whether normal hemostasis or bleeding or clotting symptoms will result. THE PLATELET Platelets are released from the megakaryocyte, likely under the influ­ ence of flow in the capillary sinuses. The normal blood platelet count is 150,000–450,000/μL. The major regulator of platelet production is the hormone thrombopoietin (TPO), which is synthesized in the liver and other organs. Synthesis is increased with inflammation and specifically by interleukin 6. TPO binds to its receptor on platelets and megakaryo­ cytes, by which it is removed from the circulation. Thus, a reduction in platelet and megakaryocyte mass increases the level of TPO, which then stimulates platelet production. Platelets circulate with an average life span of 7–10 days. Approximately one-third of the platelets reside in the spleen, and this number increases in proportion to splenic size, although the platelet count rarely decreases to <40,000/μL as the spleen enlarges. Platelets are physiologically very active, but are anucleate, and thus have limited capacity to synthesize new proteins. Normal vascular endothelium contributes to preventing thrombosis by inhibiting platelet function (Chap. 69). When vascular endothelium is injured, these inhibitory effects are overcome, and platelets adhere to the exposed intimal surface primarily through VWF, a large multi­ meric protein present in both plasma and in the extracellular matrix of the subendothelial vessel wall. Platelet adhesion results in the genera­ tion of intracellular signals that lead to activation of the platelet glyco­ protein (Gp) IIb/IIIa (αIIbβ3) receptor and resultant platelet aggregation. Activated platelets undergo release of their granule contents, which include nucleotides, adhesive proteins, growth factors, and procoagu­ lants that serve to promote platelet aggregation and blood clot forma­ tion and influence the environment of the forming clot. During platelet aggregation, additional platelets are recruited to the site of injury, leading to the formation of an occlusive platelet thrombus. The platelet plug is stabilized by the fibrin mesh that develops simultaneously as the product of the coagulation cascade. THE VESSEL WALL Endothelial cells line the surface of the entire circulatory tree, totaling 1–6 × 1013 cells, enough to cover a surface area equivalent to about six tennis courts. The endothelium is physiologically active, control­ ling vascular permeability, flow of biologically active molecules and nutrients, blood cell interactions with the vessel wall, the inflammatory response, and angiogenesis. The endothelium normally presents an antithrombotic surface (Chap. 69) but rapidly becomes prothrombotic when stimulated, which promotes coagulation, inhibits fibrinolysis, and activates plate­ lets. In many cases, endothelium-derived vasodilators are also platelet inhibitors (e.g., nitric oxide), and conversely, endothelium-derived vasoconstrictors (e.g., endothelin) can also be platelet activators. The net effect of vasodilation and inhibition of platelet function is to promote blood fluidity, whereas the net effect of vasoconstriction and platelet activation is to promote thrombosis. Thus, blood fluidity and hemostasis are regulated by the balance of antithrombotic/prothrom­ botic and vasodilatory/vasoconstrictor properties of endothelial cells. DISORDERS OF PLATELETS ■ ■THROMBOCYTOPENIA Thrombocytopenia results from one or more of three processes: (1) decreased bone marrow production; (2) sequestration, usually in an enlarged spleen; and/or (3) increased platelet destruction. Disorders of production may be either inherited or acquired. In evaluating a patient with thrombocytopenia, a key step is to review the peripheral blood smear and to first rule out “pseudothrombocytopenia,” particularly in a patient without an apparent cause for the thrombocytopenia. Pseu­ dothrombocytopenia (Fig. 120-1B) is an in vitro artifact resulting from platelet agglutination via antibodies (usually IgG, but also IgM and IgA) when the calcium content is decreased by blood collection in eth­ ylenediamine tetraacetic (EDTA) (the anticoagulant present in tubes [purple top] used to collect blood for complete blood counts [CBCs]). If a low platelet count is obtained in EDTA-anticoagulated blood, a blood smear should be evaluated and a platelet count determined in blood collected into sodium citrate (blue top tube) or heparin (green top tube), or a smear of freshly obtained unanticoagulated blood, such as from a finger stick, can be examined. CHAPTER 120 Disorders of Platelets and Vessel Wall APPROACH TO THE PATIENT Thrombocytopenia The history and physical examination, results of the CBC, and review of the peripheral blood smear are all critical components in the initial evaluation of thrombocytopenic patients (Fig. 120-2). The overall health of the patient and whether they are receiving drug treatment will influence the differential diagnosis. A healthy young adult with thrombocytopenia will have a much more lim­ ited differential diagnosis than an ill hospitalized patient who is receiving multiple medications. Except in less common inherited disorders, decreased platelet production usually results from bone marrow disorders that also affect red blood cell (RBC) and/or white blood cell (WBC) production. Because myelodysplasia can present with isolated thrombocytopenia, the bone marrow should be exam­ ined in patients presenting with isolated thrombocytopenia who are older than 60 years of age or who do not respond to initial therapy. While inherited thrombocytopenia is uncommon, any prior platelet counts should be retrieved and a family history regarding thrombo­ cytopenia obtained. A careful history of drug ingestion should be obtained, including nonprescription and herbal remedies, because drugs are the most common cause of thrombocytopenia. The physical examination can document an enlarged spleen, evidence of chronic liver disease, and other underlying disorders. Mild to moderate splenomegaly may be difficult to appreciate in many individuals due to body habitus and/or obesity but can be eas­ ily assessed by abdominal ultrasound. A platelet count of approxi­ mately 5000–10,000 is required to maintain vascular integrity in the microcirculation. When the count is markedly decreased, petechiae first appear in areas of increased venous pressure, the ankles and feet in an ambulatory patient. Petechiae are pinpoint, nonblanching hemorrhages and are usually a sign of a decreased platelet num­ ber and not platelet dysfunction. Wet purpura, blood blisters that form on the oral mucosa, are thought to denote an increased risk of life-threatening hemorrhage in the thrombocytopenic patient. Excessive bruising is seen in disorders of both platelet number and function. Infection-Induced Thrombocytopenia  Many viral and bacte­ rial infections result in thrombocytopenia and are the most common A PART 4 Oncology and Hematology B FIGURE 120-1  Photomicrographs of peripheral blood smears. A. Normal peripheral blood. B. Platelet clumping in pseudothrombocytopenia. C. Abnormal large platelet in autosomal dominant macrothrombocytopenia. D. Schistocytes and decreased platelets in microangiopathic hemolytic anemia. Platelet count <150,000/µL Hemoglobin and white blood count Normal Abnormal Bone marrow examination Peripheral blood smear Platelets clumped: redraw in sodium citrate or heparin Fragmented red blood cells Normal RBC morphology; platelets normal or increased in size Microangiopathic hemolytic anemias (e.g., DIC, TTP) Consider: Drug-induced thrombocytopenia Infection-induced thrombocytopenia Idiopathic immune thrombocytopenia Congenital thrombocytopenia FIGURE 120-2  Algorithm for evaluating the thrombocytopenic patient. DIC, disseminated intravascular coagulation; RBC, red blood cell; TTP, thrombotic thrombocytopenic purpura. C D noniatrogenic cause of thrombocytopenia. This may or may not be associated with laboratory evidence of disseminated intravascular coagulation (DIC), which is most commonly seen in patients with systemic infections with gram-negative bacteria and is seen in patients ill with COVID-19. Infections can affect both platelet production and platelet survival. In addition, immune mechanisms can be at work, as in infectious mononucleosis and early HIV infection. Late in HIV infection, pancytopenia and decreased and dysplastic platelet produc­ tion are more common. Immune-mediated thrombocytopenia in children usually follows a viral infection and almost always resolves spontaneously. This association of infection with immune thrombocy­ topenic purpura is less clear in adults. Drug-Induced Thrombocytopenia  Many drugs have been asso­ ciated with thrombocytopenia. A predictable decrease in platelet count occurs after treatment with many chemotherapeutic drugs due to bone marrow suppression (Chap. 78). Drugs that cause isolated thrombocy­ topenia and have been confirmed with positive laboratory testing are listed in Table 120-1, but all drugs should be suspect in a patient with thrombocytopenia without an apparent cause and should be stopped, or substituted, if possible. Although not as well studied, herbal and over-the-counter preparations may also result in thrombocytopenia and should be discontinued in patients who are thrombocytopenic. Classic drug-dependent antibodies are antibodies that react with specific platelet surface antigens and result in thrombocytopenia only when the drug is present. Many drugs are capable of inducing these antibodies, but for some reason, they are more common with quinine and sulfonamides. Drug-dependent antibody binding can be demon­ strated by laboratory assays, showing antibody binding in the presence TABLE 120-1  Drugs Reported as Definitely or Probably Causing Isolated Thrombocytopeniaa Abciximab Acetaminophen Amiodarone Amlodipine Ampicillin Carbamazepine Ceftriaxone Cephamandole Ciprofloxacin Diazepam Eptifibatide Furosemide Gold Haloperidol Heparin Ibuprofen Lorazepam Mirtazapine Naproxen Oxaliplatin Penicillin Phenytoin Piperacillin Quinidine Quinine Ranitidine Rosiglitazone Roxifiban Sulfisoxazole Suramin Tirofiban Tranilast Trimethoprim/sulfamethoxazole Vancomycin aBased on scoring requiring a compatible clinical picture and positive laboratory testing. Note, this is not inclusive of newer medications. Source: Adapted from DM Arnold et al: J Thromb Hemost 11:169, 2013. of, but not without, the drug present in the assay. The thrombocytope­ nia typically occurs after a period of initial exposure (median length 21 days), or upon reexposure, and usually resolves in 7–10 days after drug withdrawal. The thrombocytopenia caused by the platelet Gp IIb/ IIIa inhibitory drugs, such as abciximab, differs in that it may occur within 24 h of initial exposure. This appears to be due to the presence of naturally occurring antibodies that cross-react with the drug bound to the platelet. Heparin-Induced Thrombocytopenia  Drug-induced throm­ bocytopenia due to heparin differs from that seen with other drugs in two major ways. (1) The thrombocytopenia is not usually severe, with nadir counts rarely <20,000/μL. (2) Heparin-induced thrombo­ cytopenia (HIT) is not associated with bleeding and, in fact, markedly increases the risk of thrombosis. The pathogenesis of HIT is complex. It results from antibody formation to a complex of the platelet-specific protein platelet factor 4 (PF4) and heparin or other glycosaminogly­ cans. The anti-heparin/PF4 antibody can activate platelets through the FcγRIIa receptor and also activate monocytes, endothelial cells, and coagulation proteins. Many patients exposed to heparin develop anti­ bodies to heparin/PF4 but do not appear to have adverse consequences. A fraction of those who develop antibodies will develop HIT, and a portion of those (up to 50%) will develop thrombosis (HITT). HIT can occur after exposure to low-molecular-weight heparin (LMWH) as well as unfractionated heparin (UFH), although it is more common with the latter. Most patients develop HIT after expo­ sure to heparin for 5–14 days (Fig. 120-3). It occurs before 5 days in those who were exposed to heparin in the prior few weeks or months HIT only if heparin in last ~100 days Risk of HIT Delayed-onset HIT occurs rarely Days of heparin (UFH or LMWH) exposure FIGURE 120-3  Time course of heparin-induced thrombocytopenia (HIT) development after heparin exposure. The timing of development after heparin exposure is a critical factor in determining the likelihood of HIT in a patient. HIT occurs early after heparin exposure in the presence of preexisting heparin/platelet factor 4 (PF4) antibodies, which disappear from circulation by ~100 days following a prior exposure. Rarely, HIT may occur later after heparin exposure (termed delayedonset HIT). In this setting, heparin/PF4 antibody testing is usually markedly positive. HIT can occur after exposure to either unfractionated (UFH) or low-molecularweight heparin (LMWH). (<~100 days) and have circulating anti-heparin/PF4 antibodies. Rarely, thrombocytopenia and thrombosis begin several days after all heparin has been stopped (termed delayed-onset HIT), and more rarely, spon­ taneous HIT, or autoimmune HIT syndrome, occurs where there is no history of heparin exposure. A syndrome similar to spontaneous HIT has been described rarely after COVID-19 vaccination with the adenovirus-based ChAdOx1-S/nCoV-19 vaccine and termed vaccineinduced immune thrombocytopenia and thrombosis (VITT). Even more rarely, a similar thrombotic syndrome can follow an adenovirus infec­ tion. then go to the 4Ts. The “4Ts” are recommended to be used in a diagnostic algorithm for HIT: thrombocytopenia, timing of platelet count drop, thrombosis and other sequelae such as localized skin reac­ tions, and other causes of thrombocytopenia not evident. Application of the 4T scoring system is very useful in excluding a diagnosis of HIT but will result in overdiagnosis of HIT in situations where thrombocy­ topenia and thrombosis due to other etiologies are common, such as in the intensive care unit. LABORATORY TESTING FOR HIT  Because of the prevalence of anti­ heparin antibodies without clinical disease, testing should be done in individuals who are at intermediate or high risk based on clinical pretest assessment. HIT (anti-heparin/PF4) antibodies can be detected using two types of assays. The most widely available are immunoassays usually with PF4/polyanion complex as the antigen. Because many patients develop antibodies but do not develop clinical HIT, the test has a low specificity for the diagnosis of HIT. This is especially true in patients who have undergone surgery requiring cardiopulmonary bypass, where approximately 50% of patients develop these antibod­ ies postoperatively. The other assay is a platelet activation assay, most commonly the serotonin release assay, which measures the ability of the patient’s serum to activate platelets in the presence of heparin in a concentration-dependent manner. This test has lower sensitivity but higher specificity than the enzyme-linked immunosorbent assay (ELISA). However, HIT remains a clinical diagnosis. CHAPTER 120 Disorders of Platelets and Vessel Wall TREATMENT Heparin-Induced Thrombocytopenia Early recognition is key in treatment of HIT, with prompt discon­ tinuation of heparin and use of alternative anticoagulants if bleeding risk does not outweigh thrombotic risk. Thrombosis is a common complication of HIT, even after heparin discontinuation, and can occur in both the venous and arterial systems. In patients diagnosed with HIT, imaging studies to evaluate the patient for thrombosis (at least lower extremity duplex Doppler imaging) are recommended. Patients requiring anticoagulation should be switched from heparin to an alternative anticoagulant. The direct thrombin inhibi­ tor (DTI) argatroban is effective in HITT. The DTI bivalirudin, the antithrombin-binding pentasaccharide fondaparinux, and direct oral anticoagulants (DOACs) appear to have efficacy, although none of these are approved by the U.S. Food and Drug Administra­ tion (FDA) for this indication. Of the DOACs, the most experience reported is with rivaroxaban. In general, an intravenous DTI should be used in acutely ill patients with transition to fondaparinux or a DOAC when they are more stable, which then allows outpatient treatment. HIT antibodies cross-react with LMWH, and these drugs should not be used in the treatment of HIT. Because of the high rate of thrombosis in patients with HIT, anti­ coagulation should be considered, even in the absence of thrombo­ sis. In patients with thrombosis, anticoagulation is continued for 3–6 months, but in patients without thrombosis, the duration of anticoagulation is less well defined, but should be continued at least until platelet recovery. An increased risk of thrombosis is present for at least 1 month after diagnosis; however, most thromboses occur early, and whether thrombosis occurs later if the patient is initially anticoagulated is unknown. Introduction of warfarin alone in the setting of HIT or HITT may precipitate thrombosis, particularly venous gangrene, presumably due to clotting activation and severely reduced levels of proteins C and S. Warfarin therapy, if started, should be overlapped with a DTI, fondaparinux, or a DOAC and started after resolution of the thrombocytopenia and lessening of the prothrombotic state. The rare VITT syndrome is characterized by high D-dimer levels and thrombosis in unusual sites like the cerebral venous sinuses. Fatal in about 20%, treatment is usually intravenous gamma globu­ lin (IVIgG) to block platelet activation through Fc receptors, the pathogenic effect of the anti–PF4-polyanion antibody, and a non­ heparin anticoagulant. Immune Thrombocytopenic Purpura  Immune thrombocyto­ penic purpura (ITP; also termed idiopathic thrombocytopenic purpura) is an acquired disorder in which there is immune-mediated destruction of platelets and possibly inhibition of platelet release from the mega­ karyocyte. In children, it is usually an acute disease, most commonly following an infection, and with a self-limited course. In adults, it is a more chronic disease, although in some adults, spontaneous remission occurs, usually within months of diagnosis. ITP is termed secondary if it is associated with an underlying disorder; autoimmune disorders, particularly systemic lupus erythematosus (SLE), and infections, such as HIV and hepatitis C, are common causes. The association of ITP with Helicobacter pylori infection is unclear but appears to have a geo­ graphic distribution. PART 4 Oncology and Hematology ITP is characterized by mucocutaneous bleeding and a low, often very low, platelet count, with an otherwise normal peripheral blood cells and smear. Patients usually present either with ecchymoses and petechiae or with thrombocytopenia incidentally found on a routine CBC. Mucocutaneous bleeding, such as oral mucosa, gastrointestinal, or heavy menstrual bleeding, may be present. Rarely, life-threatening, including central nervous system, bleeding can occur. Wet purpura (blood blisters in the mouth) and retinal hemorrhages may herald lifethreatening bleeding. LABORATORY TESTING IN ITP  Laboratory testing for antibodies (sero­ logic testing) is usually not helpful due to the low sensitivity and specificity of the current tests. Bone marrow examination can be reserved for those who have other signs or laboratory abnormalities not explained by ITP or in patients who do not respond to initial therapy. The peripheral blood smear may show large platelets, with otherwise normal morphology. Depending on the bleeding history, iron-deficiency anemia may be present. Laboratory testing is performed to evaluate for secondary causes of ITP and should include testing for HIV infection and hepatitis C (and other infections if indicated). Serologic testing for SLE, serum protein electrophoresis, immunoglobulin levels to potentially detect hypogam­ maglobulinemia, selective testing for IgA deficiency or monoclonal gammopathies, and testing for H. pylori infection should be consid­ ered, depending on the clinical circumstance. If anemia is present, direct antiglobulin testing (Coombs’ test) should be performed to rule out combined autoimmune hemolytic anemia with ITP (Evans’ syndrome). TREATMENT Immune Thrombocytopenic Purpura The treatment of ITP uses drugs that decrease reticuloendothelial uptake of the antibody-bound platelet, decrease antibody produc­ tion, and/or increase platelet production. The diagnosis of ITP does not necessarily mean that treatment must be instituted. Patients with platelet counts >30,000/μL appear not to have increased mor­ tality related to the thrombocytopenia. Initial treatment in patients without significant bleeding symp­ toms, severe thrombocytopenia (<5000/μL), or signs of impending bleeding (e.g., retinal hemorrhage or large oral mucosal hemor­ rhages) can be instituted as an outpatient using single agents. Tra­ ditionally, this has been prednisone at 1 mg/kg or a 4-day course of dexamethasone, 40 mg/d, although Rh0(D) immune globulin therapy, at 50–75 μg/kg, is also being used in this setting. Rh0(D) immune globulin must be used only in Rh-positive patients because the mechanism of action is production of limited hemolysis, with antibody-coated cells “saturating” the Fc receptors, inhibiting Fc receptor function. Monitoring patients for 8 h after infusion is now advised by the FDA because of the rare complication of severe intravascular hemolysis. IVIgG, which is pooled, primarily IgG antibodies, also blocks the Fc receptor system, but appears to work primarily through different mechanism(s). IVIgG has more efficacy than anti-Rh0(D) in postsplenectomized patients. IVIgG is dosed at 1–2 g/kg total, given over 1–5 days. Side effects are usually related to the volume of infusion and infrequently include aseptic meningitis and renal failure. All immunoglobulin preparations are derived from human plasma and undergo treatment for viral inactivation. Rituximab, an anti-CD20 (B-cell) antibody, has shown efficacy in the treatment of refractory ITP, although long-lasting remission only occurs in approximately 30% of patients. TPO receptor ago­ nists (TPO-RA), administered subcutaneously (romiplostim) or orally (eltrombopag, avatrombopag), are effective in raising platelet counts in patients with chronic ITP. For patients with severe ITP and/or symptoms of bleeding, hospital admission is required, and combined-modality therapy is given using high-dose glucocorticoids with IVIgG or anti-Rh0(D) therapy and, as needed, additional immunosuppressive agents. For chronic ITP, broad immune therapy and splenectomy are now generally used less frequently compared to TPO-RAs due to unfavorable side effects and a negative impact on quality of life. Newer drugs are under study. In individuals who achieve a complete response to a TPO-RA, many will maintain a sustained response off therapy. In patients who are to undergo splenectomy, vaccination against encapsulated organisms (especially pneumococcus, but also menin­ gococcus and Haemophilus influenzae, depending on patient age and potential exposure) is recommended. Accessory spleens are a very rare cause of relapse. Inherited Thrombocytopenia  Thrombocytopenia is rarely inherited, either as an isolated finding or as part of a syndrome, and may be inherited in an autosomal dominant, autosomal recessive, or X-linked pattern. Multiple genetic variants have now been identified in individuals with isolated thrombocytopenia and cytopenic syndromes, some of which carry an increased risk of hematologic malignancy. Many forms of autosomal dominant macrothrombocytopenia are now known to be associated with variants in the nonmuscle myosin heavy chain MYH9 gene. These include the May-Hegglin anomaly, and Sebastian, Epstein’s, and Fechtner syndromes, all of which have distinct distinguishing features. A common feature of these disorders is large platelets (Fig. 120-1C). It is important that family history be explored in any individual with unexplained thrombocytopenia. ■ ■THROMBOTIC THROMBOCYTOPENIC PURPURA AND HEMOLYTIC-UREMIC SYNDROME Thrombotic thrombocytopenic microangiopathies are a group of dis­ orders characterized by microangiopathic hemolytic anemia (MAHA) defined by thrombocytopenia and fragmented RBCs (Fig. 120-1D) on peripheral blood smear, laboratory evidence of hemolysis (elevated lac­ tate dehydrogenase [LDH] and unconjugated bilirubin and decreased haptoglobin), and microvascular thrombosis. They include thrombotic thrombocytopenic purpura (TTP) and hemolytic-uremic syndrome (HUS), as well as syndromes complicating bone marrow transplanta­ tion, certain medications and infections, pregnancy, and vasculitis. In DIC, although thrombocytopenia and microangiopathy are seen, a coagulopathy predominates, with consumption of clotting factors and fibrinogen resulting in an elevated prothrombin time (PT) and often activated partial thromboplastin time (aPTT). The PT and aPTT are characteristically normal in TTP or HUS. Thrombotic Thrombocytopenic Purpura  TTP was first described in 1924 by Eli Moschcowitz and characterized by a pentad of findings that include microangiopathic hemolytic anemia, thrombo­ cytopenia, renal failure, neurologic findings, and fever. The full-blown VWF and Platelet Adhesion Blood flow Protease No protease “Ultralarge” multimers Normal multimers TTP? FIGURE 120-4  Pathogenesis of thrombotic thrombocytopenic purpura (TTP). Normally the ultra-high-molecular-weight multimers of von Willebrand factor (VWF) produced by the endothelial cells are processed into smaller multimers by a plasma metalloproteinase called ADAMTS13. In TTP, the activity of the protease is inhibited, and the ultra-high-molecular-weight multimers of VWF initiate platelet aggregation and thrombosis. syndrome is less commonly seen now, probably due to earlier diag­ nosis. The introduction of treatment with plasma exchange markedly improved the prognosis in patients, with a decrease in mortality from 85–100% to 10–30%. The pathogenesis of inherited (Upshaw-Schulman syndrome) and idiopathic TTP (ITTP) is related to a deficiency of, or antibodies to, the metalloprotease ADAMTS13, which cleaves VWF. VWF is normally secreted as ultra-large multimers, which are then cleaved by ADAMTS13. The persistence of ultra-large VWF molecules is thought to contribute to pathogenic platelet adhesion and aggregation (Fig. 120-4). This defect alone, however, is not sufficient to result in TTP because individuals with a congenital absence of ADAMTS13 develop TTP only episodically, including during first pregnancy. The level of ADAMTS13 activity, as well as antibodies to ADAMTS13, can be detected by laboratory assays, which play a critical role in the dif­ ferential diagnosis of MAHA. ADAMTS13 activity levels of <10% are diagnostic of TTP. Idiopathic TTP appears to be more common in women than in men. No geographic or racial distribution has been defined. TTP is more common in patients with HIV infection and in pregnant women. Medication-related MAHA may be secondary to antibody formation (ticlopidine and possibly clopidogrel) or direct endothelial toxicity (cyclosporine, gemcitabine, mitomycin C, tacrolimus), although this is not always so clear, and fear of withholding treatment, as well as lack of other treatment alternatives, may result in initial application of plasma exchange. However, withdrawal, or reduction in dose, of endothelial toxic agents usually decreases the microangiopathy. TREATMENT Thrombotic Thrombocytopenic Purpura TTP is a devastating disease if not diagnosed and treated promptly. In patients presenting with new thrombocytopenia, with or without evidence of renal insufficiency and other elements of classic TTP, laboratory data (PT, aPTT, CBC with platelet count and peripheral smear, ADAMTS13 activity, LDH, bilirubin, haptoglobin, direct antiglobulin assay) should be obtained to rule out DIC and to evalu­ ate for evidence of MAHA. Therapeutic plasma exchange (TPE) remains the mainstay of treatment of TTP. TPE is continued until the platelet count is normal and signs of hemolysis are resolved for at least 2 days. Although never evaluated in clinical trials, the use of glucocorti­ coids seems a reasonable approach but should only be used as an adjunct to plasma exchange. The addition of rituximab to initial therapy decreases the risk of relapse. Caplacizumab, an anti-VWF nanobody, decreases mortality and burden of care when used in patients with ADAMTS13 <10% or with high clinical probability of disease. Guidelines from the International Society of Thrombosis and Hemostasis recommend starting caplacizumab and rituximab only in individuals with diagnostic ADAMTS13 levels (usually <10%) and, additionally for rituximab, in patients with evidence of an inhibitor, given potential side effects and costs. Patients with persistently low ADAMTS13 have a greater risk of ongoing sequelae including stroke. There is a significant relapse rate; in patients treated with TPE, 25–45% of patients relapse within 30 days of initial “remission,” and 12–40% of patients have late relapses. Relapses are more frequent in patients with severe ADAMTS13 deficiency at presentation. Treatment of patients with TTP relapses should be initiated before confirmatory laboratory assays are available. CHAPTER 120 Hemolytic-Uremic Syndrome  HUS is a syndrome character­ ized by acute renal failure, microangiopathic hemolytic anemia, and thrombocytopenia. It is seen preceded by an episode of diarrhea, often hemorrhagic in nature, predominantly in children. Escherichia coli O157:H7 is the most frequent, although not only, etiologic serotype. HUS not associated with diarrhea is more heterogeneous in presenta­ tion and course. Atypical HUS (aHUS) is usually due to genetic defects in complement genes or antibodies directed against complementary regulatory proteins that result in chronic complement activation. Laboratory testing for DNA variants in complement regulatory genes is available, although assigning pathogenicity to variants remains chal­ lenging. Currently, a commercially available functional assay is not available that is diagnostic of the disease. Disorders of Platelets and Vessel Wall TREATMENT Hemolytic-Uremic Syndrome Treatment of HUS is primarily supportive. In HUS associated with diarrhea, many (~40%) children require at least some period of support with dialysis; however, the overall mortality is <5%. In HUS not associated with diarrhea, the mortality is higher, approximately 26%. Plasma infusion or plasma exchange has not been shown to alter the overall course in HUS or aHUS, except in patients with antibodies to factor H. ADAMTS13 levels are generally reported to be normal in HUS, although occasionally they have been reported to be decreased. In patients with aHUS, anticomplement therapy has efficacy in resolution of aHUS and improving or preserving renal function. Patients with aHUS may initially be treated with plasma exchange, until the ADAMTS13 level is returned and the diagnosis is more clear, since aHUS remains a diagnosis of exclu­ sion. However, plasma exchange has not been shown to affect clini­ cal outcomes in aHUS. ■ ■THROMBOCYTOSIS Thrombocytosis is almost always due to (1) iron deficiency; (2) inflammation, cancer, or infection (reactive thrombocytosis); or (3) an underlying myeloproliferative process (essential thrombocythemia or polycythemia vera) (Chap. 108) or, rarely, the 5q– myelodysplastic process (Chap. 107). Patients presenting with an elevated platelet count should be evaluated for underlying inflammation and malignancy, and iron deficiency should be ruled out. Thrombocytosis in response to acute or chronic inflammation has not been clearly associated with an increased thrombotic risk. In fact, patients with markedly elevated platelet counts (>1.5 million), usually seen in the setting of a myelopro­ liferative disorder, have an increased risk of bleeding. This appears to be due, at least in part, to acquired von Willebrand disease (VWD) due to platelet-VWF binding and removal from the circulation. ■ ■QUALITATIVE DISORDERS OF PLATELET FUNCTION Inherited Disorders of Platelet Function  Inherited platelet function disorders are thought to be relatively rare, although the preva­ lence of mild disorders of platelet function is unclear, in part because our testing for such disorders is suboptimal. Rare qualitative disorders include the autosomal recessive disorders Glanzmann’s thrombasthe­ nia (absence of the platelet Gp IIb/IIIa receptor) and Bernard-Soulier syndrome (absence of the platelet Gp Ib-IX-V receptor). Both are inherited in an autosomal recessive fashion and present with bleeding symptoms in childhood. Platelet storage pool disorder (SPD) is the classic autosomal domi­ nant qualitative platelet disorder. This results from abnormalities of platelet granule formation. It is also seen as a part of inherited disorders of granule formation, such as Hermansky-Pudlak syndrome. Bleeding symptoms in SPD are variable but often are mild. The most common inherited disorders of platelet function prevent normal secretion of granule content and are termed secretion defects. An increasing number of genetic variants are being found in patients with these disorders, although assigning pathogenicity remains challenging. PART 4 Oncology and Hematology TREATMENT Inherited Disorders of Platelet Dysfunction Bleeding symptoms or prevention of bleeding in patients with severe platelet dysfunction frequently requires platelet transfusion. Care must be taken to limit the risk of alloimmunization by limit­ ing exposure and using human leukocyte antigen–matched single donor platelets for transfusion when needed. Recombinant factor VIIa (rFVIIa) is FDA approved in Glanzmann’s thrombasthenia and Bernard Soulier syndrome where use can avoid platelet alloim­ munization and antireceptor antibody formation. Platelet disorders associated with milder bleeding symptoms frequently respond to desmopressin (1-deamino-8-d-arginine vasopressin [DDAVP]). DDAVP increases plasma VWF and factor VIII levels; it may also have a direct effect on platelet function. Particularly for mucosal bleeding symptoms, antifibrinolytic therapy (tranexamic acid or ε-aminocaproic acid) is used alone or in conjunction with DDAVP or platelet therapy. Acquired Disorders of Platelet Function  Acquired platelet dysfunction is common, usually due to medications, either intention­ ally as with antiplatelet therapy or unintentionally as with high-dose penicillins. Acquired platelet dysfunction occurs in uremia. This is likely multifactorial, but the resultant effect is defective adhesion and activation. The platelet defect is improved most by dialysis but may also be improved by increasing the hematocrit to 27–32%, giving DDAVP (0.3 μg/kg), or use of conjugated estrogens. Platelet dysfunction also occurs with cardiopulmonary bypass due to the effect of the artificial circuit on platelets, and bleeding symptoms respond to platelet transfu­ sion. Platelet dysfunction seen with underlying hematologic disorders can result from nonspecific interference by circulating paraproteins or intrinsic platelet defects in myeloproliferative and myelodysplastic syndromes. ■ ■VON WILLEBRAND DISEASE VWD is the most common inherited bleeding disorder, with preva­ lence of symptomatic disease of 1 in 1000 to 1 in 10,000 individuals. VWF serves two roles: (1) as the major adhesion molecule that tethers the platelet to the exposed subendothelium; and (2) as the binding TABLE 120-2  Laboratory Diagnosis of von Willebrand Disease (VWD) VWF ANTIGEN VWF ACTIVITY FVIII ACTIVITY MULTIMER TYPE aPTT Nl or ↑ ↓ ↓ ↓ Normal distribution, decreased in quantity 2A Nl or ↑ ↓ ↓ ↓ ↓ Loss of high- and intermediate-MW multimers 2Ba Nl or ↑ ↓ ↓ ↓ ↓ Loss of high-MW multimers 2M Nl or ↑ ↓ ↓ ↓ ↓ Normal distribution, decreased in quantity 2N ↑↑ Nl or ↓b Nl or ↓b ↓↓ Normal distribution ↑↑ ↓↓ ↓↓ ↓↓ Absent aUsually also decreased platelet count. bFor type 2N, in the homozygous state, factor VIII is very low; in the heterozygous state, it is only seen in conjunction with type 1 VWD. Abbreviations: aPTT, activated partial thromboplastin time; F, factor; MW, molecular weight; Nl, normal; VWF, von Willebrand factor. protein for factor VIII (FVIII), resulting in significant prolongation of the FVIII half-life in circulation. The platelet-adhesive function of VWF is critically dependent on the presence of large VWF multim­ ers, whereas FVIII binding is not. Most of the symptoms of VWD are “platelet-like” except in more severe VWD when the FVIII is low enough to produce symptoms similar to those found in FVIII defi­ ciency (hemophilia A). VWD has been classified into three major types, with four subtypes of type 2 (Table 120-2). By far, the most common type of VWD is type 1 disease, with a parallel decrease in VWF protein, VWF function, and FVIII levels, accounting for at least 80% of cases. Type 1C is a subtype associated with increased VWF clearance. In type 1 VWD, patients have predominantly mucosal bleeding symptoms, although procedurerelated and other bleeding is also seen. Bleeding symptoms are uncom­ mon in infancy and usually manifest later in childhood with excessive bruising and epistaxis. Because these symptoms occur commonly in childhood, the clinician should particularly note bruising at sites unlikely to be traumatized and/or prolonged epistaxis requiring medi­ cal attention. Heavy menstrual bleeding is a common manifestation of VWD. Menstrual bleeding resulting in anemia should warrant an evaluation for VWD and, if negative, functional platelet disorders and other bleeding disorders. Type 1 VWD may first manifest with dental extractions, particularly wisdom tooth extraction, or tonsillectomy. Not all patients with low VWF levels have bleeding symptoms. Whether patients bleed or not will depend on the overall hemostatic balance they have inherited, along with environmental influences and the type of hemostatic challenges they experience. Although the inheritance of VWD is autosomal, many factors modulate both VWF levels and bleeding symptoms. These have not all been defined, but include blood type, thyroid hormone status, race, stress, exercise, hor­ monal (both endogenous and exogenous) influences, and modulators of VWF clearance. Patients with type O blood have VWF protein levels of approximately one-half those of patients with AB blood type, and in fact, the normal range for patients with type O blood overlaps that which has been considered diagnostic for VWD. Patients with mildly decreased VWF levels should be diagnosed with VWD only in the set­ ting of bleeding symptoms and/or a family history of VWD. Patients with type 2 VWD have functional defects; thus, the VWF antigen measurement is significantly higher than the test of function. For types 2A, 2B, and 2M VWD, platelet-binding and/or collagen-binding VWF activity is decreased. In type 2A VWD, the impaired function is due either to increased susceptibility to cleavage by ADAMTS13, result­ ing in loss of intermediate- and high-molecular-weight multimers, or to decreased production of these multimers by the cell. Type 2B VWD results from gain-of-function DNA variants that result in increased binding of VWF to platelets in circulation with subsequent increased ADAMTS13 cleavage and clearance. The resulting VWF in the patients’ plasma lacks the highest molecular-weight multimers, and the platelet count is usually modestly reduced, but not uniformly. Type 2M occurs as a consequence of DNA variants that result in a dysfunctional protein not affecting multimer structure. Type 2N VWD is due to variants in the VWF gene that affect bind­ ing of FVIII. As FVIII is stabilized by binding to VWF, the FVIII in patients with type 2N VWD has a very short half-life, and the FVIII level is markedly decreased. This is sometimes termed autosomal hemophilia. Type 3 VWD, or severe VWD, describes patients with virtually no VWF protein and usually FVIII levels <10%. Patients experience mucosal and joint bleeding, surgery-related bleeding, and other bleeding symptoms. Some patients with type 3 VWD, particu­ larly those with large VWF gene deletions, are at risk of developing antibodies to infused VWF. Acquired VWD or von Willebrand syndrome can be seen in patients with underlying lymphoproliferative disorders, including monoclonal gammopathies of underdetermined significance (MGUS), multiple myeloma, and Waldenström’s macroglobulinemia. It is seen most com­ monly in the setting of MGUS and should be suspected in patients, particularly elderly patients, with a new onset of severe mucosal bleeding symptoms. Laboratory evidence of acquired VWD is found in patients with cardiac valvular disease. Heyde’s syndrome (aortic stenosis with gastrointestinal bleeding) is attributed to the presence of angiodysplasia of the gastrointestinal tract in patients with aortic stenosis. The shear stress on blood passing through the stenotic aortic valve appears to unfold VWF, making it susceptible to proteolysis. Consequently, large multimer forms are lost, leading to an acquired type 2 VWD, but return when the stenotic valve is replaced. TREATMENT Von Willebrand Disease The mainstay of treatment for type 1 VWD is DDAVP (desmopres­ sin), which results in release of VWF and FVIII from endothelial stores. DDAVP can be given intravenously, by high-concentration intranasal spray (1.5 mg/mL), or when a concentrated form is available, by subcutaneous injection. The peak activity when given intravenously is approximately 30 min, whereas it is 2 h when given intranasally. The usual dose is 0.3 μg/kg intravenously or two squirts (one in each nostril) for patients >50 kg (one squirt for those <50 kg). It is recommended that patients with VWD be tested with DDAVP to assess their response before using it. In patients who respond well (increase in laboratory values greater than twofold with levels >50% for at least 4 h), it can be used for procedures with minor to moderate risk of bleeding. Depending on the procedure, additional doses may be needed; it is usually given every 12–24 h. Less frequent dosing may result in less tachyphylaxis, which occurs when synthesis cannot compensate for the released stores. The major side effect of DDAVP is hyponatremia due to decreased free water clearance. This occurs most commonly in the very young and the very old, but fluid restriction should be advised for all patients for the 24 h following each dose. Some patients with type 2A VWD respond to DDAVP such that it can be used for minor procedures. For the other subtypes, for type 3 disease, and for major procedures requiring longer periods of normal hemostasis, VWF replacement can be given. Virally inac­ tivated VWF-plasma-derived and recombinant factor concentrates are safer than cryoprecipitate as the replacement product. Antifibrinolytic therapy using either tranexamic acid (TXA) or ε-aminocaproic acid is an important therapy, either alone or in an adjunctive capacity, particularly for the prevention or treatment of mucosal bleeding. These agents are particularly useful in treat­ ment of heavy menstrual bleeding (TXA 1300 mg every 8 h) and postpartum hemorrhage, as prophylaxis for dental procedures, and with DDAVP or factor concentrate for dental extractions, tonsillec­ tomies, and prostate procedures. Antifibrinolytic agents are contra­ indicated in the setting of upper urinary tract bleeding due to the risk of ureteral obstruction. ■ ■DISORDERS OF THE VESSEL WALL The vessel wall is an integral part of hemostasis, and separation of a fluid phase is artificial, particularly in disorders such as TTP or HIT that clearly involve the endothelium as well. Inflammation localized to the vessel wall, such as vasculitis, and inherited connective tissue disorders are abnormalities inherent to the vessel wall. Metabolic and Inflammatory Disorders  Acute febrile illnesses may result in vascular damage. This can result from immune com­ plexes containing viral antigens or the viruses themselves. Certain pathogens, such as the rickettsiae causing Rocky Mountain spotted fever, replicate in endothelial cells and damage them. SARS-CoV-2 also infects endothelial cells, resulting in activation and damage con­ tributing to COVID-19 pathogenicity. Vascular purpura may occur in patients with polyclonal gammopathies but more commonly occurs in those with monoclonal gammopathies, including Waldenström’s mac­ roglobulinemia, multiple myeloma, and cryoglobulinemia. Patients with mixed cryoglobulinemia develop a more extensive maculopapular rash due to immune complex–mediated damage to the vessel wall. Patients with scurvy (vitamin C deficiency) develop painful epi­ sodes of perifollicular skin bleeding as well as more systemic bleed­ ing symptoms. Vitamin C is needed to synthesize hydroxyproline, an essential constituent of collagen. Patients with Cushing’s syndrome or on chronic glucocorticoid therapy develop skin bleeding and easy bruising due to atrophy of supporting connective tissue. A similar phenomenon is seen with aging, where following minor trauma, blood spreads superficially under the epidermis. This has been termed senile purpura. It is most common on skin that has been previously damaged by sun exposure. CHAPTER 120 Disorders of Platelets and Vessel Wall Immunoglobulin A vasculitis, formerly called Henoch-Schönlein purpura, is a distinct, self-limited type of vasculitis that occurs in chil­ dren and young adults. Patients have an acute inflammatory reaction with IgA and complement components in capillaries, mesangial tissues, and small arterioles leading to increased vascular permeability and localized hemorrhage. The syndrome is often preceded by an upper respiratory infection, commonly with streptococcal pharyngitis, or is triggered by drug or food allergies. Patients develop a purpuric rash on the extensor surfaces of the arms and legs, usually accompanied by polyarthralgias or arthritis, abdominal pain, and hematuria from focal glomerulonephritis. All coagulation tests are normal, but renal impair­ ment may occur. Glucocorticoids can provide symptomatic relief but do not alter the course of the illness. Inherited Disorders of the Vessel Wall  Patients with inherited disorders of the connective tissue matrix, such as Marfan’s syndrome, Ehlers-Danlos syndrome, and pseudoxanthoma elasticum, frequently report easy bruising. Inherited vascular abnormalities can result in increased bleeding. This is notably seen in hereditary hemorrhagic telangiectasia (HHT, or Osler-Weber-Rendu disease), a disorder where abnormal telangiectatic capillaries result in frequent bleeding episodes, primarily from the nose and gastrointestinal tract. Arteriovenous malformation (AVM) in the lung, brain, and liver may also occur in HHT. The telangiectasia can often be visualized on the oral and nasal mucosa. Signs and symptoms develop over time. Epistaxis begins, on average, at the age of 12 and occurs in >95% of affected individuals by middle age. Approximately 25% have gastrointestinal bleeding usu­ ally beginning after the age of 50. HHT is caused by pathogenic DNA variants in a number of genes involved in the TGFβ/BMP signaling cascade. ■ ■FURTHER READING Boender J et al: A diagnostic approach to mild bleeding disorders. J Thromb Haemost 14:1507, 2016. Cines DB, Greinacher A: Vaccine-induced immune thrombotic thrombocytopenia. Blood 141:1659, 2023. Connell NT: ASH ISTH NHF WFH 2021 guidelines on the manage­ ment of von Willebrand disease. Blood Adv 5:301, 2021. Cuker A et al: American Society of Hematology 2018 guidelines for management of venous thromboembolism: Heparin-induced throm­ bocytopenia. Blood Adv 2:23360, 2018. # 52 - 121 Coagulation Disorders ### 121 Coagulation Disorders Gomez K: Advances in the diagnosis of heritable platelet disorders. Blood Rev 56:100972, 2022. James PD et al: ASH ISTH NHF WFH 2021 guidelines on the diagno­ sis of von Willebrand disease. Blood Adv 5:280, 2021. Jiang D et al: Changing paradigms in ITP management: Newer tools for an old disease. Transfus Med Rev 36:188, 2022. Jokiranta TS: HUS and atypical HUS. Blood 129:2847, 2017. May J et al: Heparin-induced thrombocytopenia: An illustrated review. Res Pract Thromb Haemost 7:100283, 2023. Skeith L et al: A practical approach to evaluating postoperative throm­ bocytopenia. Blood Adv 4:776, 2020. Vayne C et al: Pathophysiology and diagnosis of drug-induced immune thrombocytopenia. J Clin Med 9:2212, 2020. Zheng XL et al: ISTH guidelines for the diagnosis of thrombotic thrombocytopenic purpura. J Thromb Hemost 18:2486, 2020. Jean M. Connors Coagulation Disorders PART 4 Oncology and Hematology Deficiencies of coagulation factors have been recognized for centuries. Patients with genetic deficiencies of plasma coagulation factors exhibit lifelong recurrent bleeding episodes into joints, muscles, and closed spaces, either spontaneously or following an injury. The most common inherited factor deficiencies are the hemophilias, X-linked diseases caused by deficiency of factor (F) VIII (hemophilia A) or FIX (hemo­ philia B). Rare congenital bleeding disorders due to deficiencies of other factors, including FII (prothrombin), FV, FVII, FX, FXI, FXIII, and fibrinogen, are commonly inherited in an autosomal recessive manner (Table 121-1). Disease phenotype often correlates with the level of factor activity. While patients can have a congenital deficiency of FXII accompanied by a significant prolongation in the activated par­ tial thromboplastin time (aPTT), FXII deficiency is not accompanied by a bleeding phenotype, likely due to redundant paths to activation of the intrinsic pathway of the coagulation cascade, including direct activation of FXI by thrombin generated through the extrinsic pathway (Fig. 121-1). Advances in characterization of the molecular basis of clotting factor deficiencies have contributed to better understanding of the disease phenotypes allowing the development of more targeted TABLE 121-1  Genetic and Laboratory Characteristics of Inherited Coagulation Disorders CLOTTING FACTOR DEFICIENCY INHERITANCE PREVALENCE IN GENERAL POPULATION LABORATORY ABNORMALITYa MINIMUM HEMOSTATIC LEVELS TREATMENT PLASMA HALF-LIFE aPTT PT TT Fibrinogen AR 1 in 1,000,000 + + + 100 mg/dL Cryoprecipitate 2–4 d Prothrombin AR 1 in 2,000,000 + + − 20–30% FFP/PCC 3–4 d Factor V AR 1 in 1,000,000 +/− +/− − 15–20% FFPc 36 h Factor VII AR 1 in 500,000 − + − 15–20% FFP/PCC 4–6 h Factor VIII X-linked 1 in 5000 + − − 30% FVIII concentrates 8–12 h Factor IX X-linked 1 in 30,000 + − − 30% FIX concentrates 18–24 h Factor X AR 1 in 1,000,000 +/− +/− − 15–20% FFP/PCC 40–60 h Factor XI AR 1 in 1,000,000 + − − 15–20% FFP 40–70 h Factor XII AR ND + − − b b 60 h HK AR ND + − − b b 150 h Prekallikrein AR ND + − − b b 35 h Factor XIII AR 1 in 2,000,000 − − +/− 2%–5% Cryoprecipitate/FXIII concentrates aValues within normal range (−) or prolonged (+). bNo risk for bleeding; treatment is not indicated. cSince platelets contain FV, platelet transfusion can be used as therapy. Abbreviations: aPTT, activated partial thromboplastin time; AR, autosomal recessive; FFP, fresh-frozen plasma; HK, high-molecular-weight kininogen; ND, not determined; PCC, prothrombin complex concentrates; PT, prothrombin time; TT, thrombin time. therapeutic approaches, including the use of small molecules, recom­ binant proteins, or cell- and gene-based therapies. The two most commonly used tests of hemostasis, the prothrombin time (PT) and the aPTT, were designed to perform the first screen for clotting factor deficiency (Fig. 121-1). An isolated prolonged PT sug­ gests FVII deficiency, whereas a prolonged aPTT indicates an intrinsic pathway factor deficiency, most commonly hemophilia A or B (FVIII or FIX, respectively) or FXI deficiency (Fig. 121-1). The prolongation of both PT and aPTT suggests a deficiency of FV, FX, FII, or fibrinogen abnormalities. A mixing study, in which the addition of normal pooled plasma to the patient’s plasma, will correct a prolonged aPTT or PT due to a factor deficiency, and is the next step in determining if there is a coagulation factor deficiency. If the clotting time does not correct, it suggests the presence of an inhibitor, an antibody to a specific factor; however, a mixing study will also detect the presence of anticoagulants. Many labs have testing methods for detecting inhibitors that neutral­ ize anticoagulants. If the mixing study corrects with normal plasma, individual factor activity assays are performed to determine which factor is deficient. Acquired deficiencies of plasma coagulation factors are more fre­ quent than congenital disorders; the most common disorders include hemorrhagic diathesis of liver disease, disseminated intravascular coagulation (DIC), and vitamin K deficiency. In these disorders, blood coagulation is hampered by the deficiency of more than one clotting factor, and the bleeding episodes are the result of perturbation of both primary (e.g., platelet and vessel wall interactions) and secondary (coagulation) hemostasis. The development of alloantibodies to coagulation plasma proteins, clinically termed inhibitors, is a relatively rare disease that often affects hemophilia A or B and FXI-deficient patients on repetitive exposure to the missing protein to control bleeding episodes. Inhibitory autoanti­ bodies also occur among subjects without genetic deficiency of clotting factors and, although rare, can be seen in the postpartum setting, as a manifestation of underlying autoimmune or neoplastic disease, or idiopathically. Rare cases of acquired inhibitors to thrombin or FV have been reported in patients receiving topical bovine thrombin prepara­ tion as a local hemostatic agent in complex surgeries. A mixing study that does not correct with the addition of normal plasma indicates the presence of an inhibitor, requiring additional tests to identify the specificity of the inhibitor and measure its titer. Inhibitor detection in patients with hemophilia is of particular importance, with yearly screening performed at most hemophilia treatment centers. The treatment of coagulation factor deficiencies in the setting of bleeding requires replacement of the deficient protein(s) using recom­ binant or purified plasma-derived products or fresh-frozen plasma 11–14 d Intrinsic Pathway Extrinsic Pathway Ca2+ aPTT PT XIa XI IX IXa Ca2+ Contact phase FXIIa PK HMWH VIII VIIIa Xa X Ca2+ Cross-linked fibrin clot FIGURE 121-1  Coagulation cascade and laboratory assessment of clotting factor deficiency by activated partial thromboplastin time (aPTT), prothrombin time (PT), thrombin time (TT), and phospholipid (PL). (FFP). Prothrombin complex concentrates (PCCs) are intermediatepurity plasma-derived factor concentrates initially used as sources of FVIII or FIX for hemophilia patients, but because they contain the vitamin K–dependent factors, they are also used for warfarin reversal. Three-factor PCC (3F-PCC) is less frequently used now for warfarin reversal because these preparations contain low levels of FVII, requir­ ing FFP as a source of FVII. Four-factor PCC (4F-PCC), especially the one used in the United States, contains FII, FIX, FX, higher levels of FVII than 3F-PCC, and protein S and protein C. HEMOPHILIA A AND B ■ ■PATHOGENESIS AND CLINICAL MANIFESTATIONS Hemophilia is an X-linked recessive hemorrhagic disease due to muta­ tions in the F8 gene (hemophilia A or classic hemophilia) or F9 gene (hemophilia B). The disease affects 1 in 10,000 males worldwide, in all ethnic groups; hemophilia A represents 80% of all cases. The large size of the F8 gene makes it more susceptible to mutation events than the smaller F9 gene. Male subjects are clinically affected; women, who carry a single mutated gene, are generally asymptomatic. However, increased bleeding tendencies with procedures are now more commonly appre­ ciated based on F8 or F9 level. Family history of the disease is absent in ~30% of cases, and in these cases, 80% of the mothers are carriers of the de novo mutated allele. More than 500 different mutations have been identified in the F8 or F9 gene. One of the most common hemo­ philia A mutations results from an inversion of the intron 22 sequence, and it is present in 40% of cases of severe hemophilia A. Advances in molecular diagnosis now permit precise identification of mutations, allowing accurate diagnosis of women carriers of the hemophilia gene in affected families. Clinically, hemophilia A and hemophilia B are indistinguishable. The disease phenotype correlates with the activity of FVIII or FIX and can be classified as severe (<1%), moderate (1–5%), or mild (6–30%). In the severe and moderate forms, the disease is characterized by bleed­ ing into the joints (hemarthrosis), soft tissues, and muscles after minor trauma or even spontaneously. Patients with mild disease experience infrequent bleeding, usually secondary to trauma. Among those with baseline FVIII or FIX activity >25%, the disease is discovered only with bleeding after major trauma or during routine laboratory tests, usu­ ally an isolated prolongation of the aPTT that requires mixing study VII VIIa/tissue factor Ca2+ PL Common Pathway X V Va PL Prothrombin Thrombin aPTT/PT Fibrinogen TT Fibrin polymer Fibrin monomer CHAPTER 121 XIIIa Coagulation Disorders evaluation. FVIII has a short circulating half-life of 25–30 min that is extended to roughly 12 h when complexed with its carrier protein von Willebrand factor (VWF). In patients without a known history of hemophilia, a diagnosis of von Willebrand disease (VWD) needs to be excluded in patients with a prolonged aPTT and low FVIII activity. Early in life, bleeding may present after circumcision or rarely as intra­ cranial hemorrhages. The disease is more evident when children begin to walk or crawl. In the severe form, the most common bleeding mani­ festations are recurrent hemarthroses, affecting primarily the knees, elbows, ankles, shoulders, and hips. Acute hemarthroses are painful, and clinical signs are local swelling and erythema. To avoid pain, the patient may adopt a fixed position, which leads eventually to muscle contractures. Very young children unable to communicate verbally show irritability and a lack of movement of the affected joint. Chronic hemarthroses are debilitating with synovial thickening and synovitis in response to the intraarticular blood. After a joint has been damaged, recurrent bleeding episodes result in the clinically recognized “target joint,” which then establishes a vicious cycle of bleeding, resulting in progressive joint deformity that in critical cases requires surgery as the only therapeutic option. Hematomas into the muscle of distal parts of the limbs may lead to external compression of arteries, veins, or nerves that can result in compartment syndrome. Bleeding into the oropharyngeal spaces, central nervous system (CNS), or retroperitoneum is life-threatening and requires immediate therapy. Retroperitoneal hemorrhages can accumulate large quantities of blood with formation of masses with calcification and inflammatory tissue reaction (pseudotumor syndrome) and also result in damage to the femoral nerve. Pseudotumors can also form in bones, especially long bones of the lower limbs. Hematuria is frequent among hemo­ philia patients, even in the absence of genitourinary pathology. It is often self-limited and may not require specific therapy. TREATMENT Hemophilia Without treatment, severe hemophilia may limit life expectancy. Advances in the blood fractionation industry during World War II resulted in the realization that plasma could be used to treat hemo­ philia, but the volumes required to achieve even modest elevation of circulating factor levels limit the utility of plasma infusion as an approach to disease management. The discovery in the 1960s that the cryoprecipitate fraction of plasma was enriched for FVIII, and the eventual purification of FVIII and FIX from plasma, led to the introduction of home infusion therapy with factor concentrates in the 1970s. The availability of factor concentrates resulted in a dra­ matic improvement in life expectancy and quality of life for people with severe hemophilia. However, the contamination of the blood supply with hepatitis viruses and HIV resulted in transmission of these bloodborne infections within the hemophilia population. The introduction of viral inactivation steps in the preparation of plasmaderived products in the mid-1980s greatly reduced the risk of HIV and hepatitis; the risks were further reduced by the production of recombinant FVIII and FIX proteins in the 1990s. It is uncommon for hemophilic patients born after 1985 to have contracted either hepatitis or HIV, and for these individuals, life expectancy is now ∼65 years. In fact, since 1998, new infections with viral hepatitis or HIV have not been reported in hemophilia patients. Factor replacement for hemophilia has been the mainstay of therapy for half a century; however, advances including uniquely functioning molecules and gene therapy have expanded treatment approaches. Factor replacement has been provided either in response to a bleeding episode or as prophylactic treatment. Primary prophy­ laxis is defined as maintaining the missing clotting factor at levels ~1% or higher on a regular basis to prevent bleeds, especially the onset of hemarthroses. Hemophilic boys receiving regular infusions of FVIII (3 days/week) or FIX (2 days/week) can reach puberty with­ out detectable joint abnormalities. Therefore, prophylactic treatment has become more common. The Centers for Disease Control and Prevention reported that >51% of children with severe hemophilia who are aged <6 years receive prophylaxis, increasing considerably from 33% in 1995. Although prophylaxis with factor concentrates is the standard care for children and adults with severe hemophilia, teenagers and young adults do not always maintain treatment due to high cost and lifestyle factors including difficulties accessing peripheral veins for infusions that occur two to three times a week or potential infectious and thrombotic risks of long-term central vein catheters. PART 4 Oncology and Hematology Treatment of hemophilia bleeds requires the following: (1) prompt initiation of factor replacement as symptoms often precede objective evidence of bleeding, especially for classic symp­ toms of bleeding into the joint in a reliable patient, headaches, or major trauma; and (2) avoidance of antiplatelet drugs. FVIII and FIX are dosed in units. One unit is defined as the amount of FVIII (100 ng/mL) or FIX (5 μg/mL) in 1 mL of normal plasma. One unit of FVIII per kilogram of body weight increases the plasma FVIII level by 2%. One can calculate the dose needed to increase FVIII levels to 100% in a 70-kg severe hemophilia patient (<1%) using the simple formula below. Thus, 3500 units of FVIII will raise the circulating level to 100%. FVIII dose (IU) = Target FVIII levels – FVIII baseline levels   × body weight (kg) × 0.5 unit/kg The doses for FIX replacement are different from those for FVIII, because FIX recovery after infusion is usually only 50% of the predicted value. Therefore, the formula for FIX replacement is as follows: FIX dose (IU) = Target FIX levels – FIX baseline levels   × body weight (kg) × 1 unit/kg The FVIII half-life of 8–12 h requires injections twice a day to maintain therapeutic levels, whereas the FIX half-life is longer, ~24 h, so that once-a-day injection is sufficient. In specific situa­ tions such as after surgery, continuous infusion of factor may be desirable because of its safety in achieving sustained factor levels at a lower total cost. Cryoprecipitate is enriched with FVIII protein bound to VWF (each bag contains ~80 IU of FVIII). This product should be used only in emergencies when factor concentrates are not available, although cryoprecipitate may be the only source of FVIII in devel­ oping countries. Mild bleeds such as uncomplicated hemarthroses or superficial hematomas require achieving an initial factor level of 30–50%. Additional doses to maintain levels of 15–25% for 2 or 3 days are indicated for severe hemarthroses, especially when these episodes affect the “target joint.” Large hematomas, or bleeds into deep muscles, require factor levels of 50% or even higher if the clinical symptoms do not improve, and factor replacement may be required for a period of 1 week or longer. The control of serious bleeds, including those that affect the oropharyngeal spaces, CNS, and the retroperitoneum, requires sustained protein levels of 50–100% for 7–10 days. Prophylactic replacement for surgery is aimed at achiev­ ing normal factor levels (100%) for a period of 7–10 days; replace­ ment can then be tapered depending on the extent of the surgical wounds. Oral surgery is associated with extensive tissue damage that usually requires factor replacement for 1–3 days coupled with oral antifibrinolytic drugs. NONTRANSFUSION THERAPY IN HEMOPHILIA DDAVP (1-Amino-8-d-Arginine Vasopressin)  DDAVP is a syn­ thetic vasopressin analogue that causes a transient rise in FVIII and VWF, but not FIX, by release from stores in vascular endothelial cells. Patients with moderate or mild hemophilia A should be tested to determine if they respond to DDAVP before use. DDAVP at doses of 0.3 μg/kg body weight, over a 20-min period, is expected to raise FVIII levels by two- to threefold over baseline, peaking between 30 and 60 min after infusion. DDAVP does not improve FVIII levels in severe hemophilia A patients because no stores are available to release. Repeated dosing of DDAVP results in tachyphy­ laxis as storage pools are depleted. After three consecutive doses, if further therapy is indicated, exogenous FVIII is required. Antifibrinolytic Drugs  Bleeding in the gums, the gastrointestinal tract, and during oral surgery can be treated with oral antifibri­ nolytic drugs such as ε-aminocaproic acid (EACA) or tranexamic acid to prevent fibrin degradation by plasmin. The duration of the treatment depending on the clinical indication is 1 week or longer. Tranexamic acid is given at doses of 25 mg/kg three to four times a day. EACA treatment requires a loading dose of 200 mg/kg (maxi­ mum of 10 g) followed by 100 mg/kg per dose (maximum 30 g/d) every 6 h. These drugs are not indicated to control hematuria because of concern for forming an occlusive clot in the lumen of genitourinary tract structures. COMPLICATIONS Inhibitor Formation  The formation of alloantibodies to FVIII or FIX is the major complication of hemophilia treatment. The prevalence of inhibitors to FVIII is estimated to be ~30% in severe hemophilia A patients and 10% among patients with nonsevere hemophilia A. Inhibitors to FIX are detected in only 3–5% of all hemophilia B patients. The high-risk group for inhibitor formation includes severe deficiency (>80% of all cases of inhibi­ tors), familial history of inhibitor, African descent, mutations in the FVIII or FIX gene resulting in deletion of large coding regions, or gross gene rearrangements. Inhibitors usually appear early in life, at a median of 2 years of age, and after 10 cumulative days of exposure. However, intensive replacement therapy such as for major surgery, intracranial bleeding, or trauma increases the risk of inhibitor formation for patients of all ages and severity; all patients require close laboratory monitoring following these events. The clinical diagnosis of an inhibitor is suspected when patients do not respond to factor replacement at therapeutic doses. Inhibi­ tors increase both morbidity and mortality in hemophilia. Because early detection of an inhibitor is critical to a successful correction of the bleeding or to eradication of the antibody, most hemophilia centers perform annual screening with aPTT and mixing studies. The Bethesda assay uses a similar principle as a mixing study and defines the specificity of the inhibitor and its titer. The results are expressed in Bethesda units (BU), in which 1 BU is the amount of antibody that neutralizes 50% of the FVIII or FIX present in normal plasma after 2 h of incubation at 37°C. Clinically, inhibitor patients are classified as low responders or high responders, with response defined as increase in antibody titer; knowledge of responder type guides therapy. Therapy for inhibitor patients has two goals: the control of acute bleeding episodes and the eradication of the inhibitor. For the control of bleeding episodes, low responders, those with titer <5 BU, respond well to high doses of human FVIII (50–100 U/kg), with minimal or no increase in the inhibitor titers. However, high-responder patients, those with initial inhibitor titer >5 BU or an anamnestic response with increase in the antibody titer to >5 BU, even if low titer initially, do not respond to FVIII. The control of bleeding episodes in high-responder patients can be achieved by using concentrates enriched for prothrombin, FVII, FIX, FX (PCCs but usually activated PCCs [aPCCs]), and recom­ binant activated FVII (FVIIa), known as “bypass agents” because they activate coagulation downstream of the inhibited/absent fac­ tor or through a different pathway (Fig. 121-1). For FIX inhibitor patients, high doses of FIX can be used (<5 BU); however, allergic or anaphylactic reactions are common in FIX inhibitor patients; thus, bypass products should be used to treat or prevent bleeding as well as for those cases of high titer inhibitors. For eradication of the inhibitory antibody, immunosuppression alone is not effective. The most effective strategy is immune tolerance induction (ITI) based on daily infusion of the missing protein until the inhibitor disappears, typically requiring periods >1 year, with success rates of ∼60%. The management of patients with severe hemophilia and inhibitors resistant to ITI is challenging. The use of anti-CD20 monoclonal antibody (rituximab) combined with ITI was thought to be effective, but although it reduces the inhibitor titers in some cases, sustained eradication is uncommon. Other Therapeutic Approaches for Hemophilia A and B  Engi­ neered clotting factors, using fusion to polyethylene glycol (FVIII, FIX), IgG1-Fc (FVIII, FIX), or albumin (FIX) or other strategies, extend the plasma half-life of the coagulation factor. A number of products have been approved for use. These extended half-life prod­ ucts (for FVIII and FIX) facilitate prophylaxis with fewer weekly injections to maintain circulating levels >1%, decreasing injections from 3 to 2 days a week in hemophilia A and to once a week for hemophilia B. Novel approaches to manipulating the coagulation cascade components, including targeting the natural anticoagulants and inhibitors of activation of coagulation, have shown promising clinical trial results but do not yet have regulatory approval. Emicizumab is an asymmetric bispecific antibody with one immunoglobulin variable chain region that binds FIXa and another that binds FX bringing them in close contact and resulting in acti­ vation of FX by FIXa. FXa subsequently cleaves prothrombin to thrombin—without the need for FVIII (Fig. 121-2). It is effective in patients with severe hemophilia A with or without inhibitors. Similar molecules are in development. After initial once-a-week subcutaneous injections (an improvement over intravenous admin­ istration of factors) for 4 weeks, patients can usually be maintained with once-a-month dosing to prevent spontaneous bleeds, an over­ whelmingly dramatic improvement in quality of life when com­ pared to even the twice-weekly infusion schedule of “long-acting” FVIII compounds. Breakthrough bleeds can occur, however, and need to be carefully managed, as a small number of patients with inhibitors treated with aPCC or recombinant FVIIa developed thrombotic events or fatal thrombotic microangiopathy. Routine aPTT and FVIII activity measurements are inaccurate when emi­ cizumab is present; to detect endogenous or infused FVIII activity, a chromogenic FVIII activity assay using bovine factor substrates is required. These X-linked disorders are ideally suited for gene therapy as small increases in plasma factor level will result in significant clinical improvement. FIX has been the most studied as the gene is smaller Bispecific antibody Factor X Factor IXa EGF2 EGF2 EGF1 EGF1 Gla Gla Factor Xa CHAPTER 121 PS-exposed PL membrane Coagulation Disorders FIGURE 121-2  Mechanism of action of emicizumab. Emicizumab is a bifunctional antibody; the two binding sites recognize different protein sequences, unlike normal antibodies where both variable regions recognize the same antigen. One arm of emicizumab recognizes factor IXa and the other factor X. It functions to bring these two factors in proximity so that factor IXa can activate factor X to factor Xa, which then cleaves prothrombin to thrombin and activates the clotting cascade. (From T Kitazawa, M Shima: Emicizumab, a humanized bispecific antibody to coagulation factors IXa and X with a factor VIIIa-cofactor activity. Int J Hematol 111:20, 2020.) and easier to package in the viral vectors used. In one approach, the sequence of a known spontaneous FIX gain-of-function mutation that has marked increase in specific activity, FIX Padua, is used so that small increments in plasma level of FIX are also accompanied by even greater increase in functional activity. The larger FVIII gene has also been successfully transferred through an adeno-associated viral vector to a few patients with hemophilia A. The early results appear promising. Complications include transaminitis and loss of gene expression for a variety of reasons. Gene therapy using adenoviral vector approaches have now been approved for patients with hemophilia A or B. Details on how to implement gene therapy, selection of appropriate patients, and follow-up monitoring are still being developed (Chap. 483). INFECTIOUS DISEASES Hemophilia patients treated with clotting factor concentrates before the development of recombinant factors in the 1990s were almost universally infected with hepatitis C virus (HCV) and HIV, which became the second leading cause of death. Co-infection of HCV and HIV, present in almost 50% of hemophilia patients, is an aggra­ vating factor for the evolution of liver disease as correction of both genetic and acquired (secondary to liver disease) factor deficiencies may be needed. Effective treatments for both HIV and HCV have altered the devastating prognosis. In some select cases with cir­ rhosis, liver transplant has been performed, which also is curative for hemophilia. EMERGING CLINICAL PROBLEMS IN AGING HEMOPHILIA PATIENTS Patients with hemophilia now live well into adulthood, with life expectancy of patients with severe hemophilia now only ~10 years shorter than the general male population and near normal in patients with mild or moderate hemophilia. The older hemophilia population has distinct needs relating to more severe arthropathy, chronic pain, and high rates of HCV and/or HIV infections. Although mortality from coronary artery disease is lower in hemophilia patients with hypocoagulability decreasing thrombus formation, atherogenesis is not prevented. Typical cardiovascular risk factors such as age, obesity, and smoking, along with physical inactivity, hypertension, and chronic renal disease, are seen in these patients as in the general population. Management of an acute ischemic event and coronary revas­ cularization should include collaboration among hematologists, cardiologists, and internists. Cancer due to HIV- and HCV-related malignancies is also a concern in this population, with hepato­ cellular carcinoma (HCC) the most common cause of death in HIV-negative patients. The recommendations for cancer screening for the general population should be the same for age-matched hemophilia patients, including routine screening for HCC. Hemophilia patients benefit from the same preventive and thera­ peutic approaches to minimize the risk of cardiovascular disease and malignancy as the general population. MANAGEMENT OF CARRIERS OF HEMOPHILIA Women carriers of hemophilia with factor levels ~50% of normal may not have an increased risk for bleeding. However, a wide range of factor activity (22–116%) due to random inactivation of the X chromosome (lyonization) can occur and lead to unexpected bleeding in women with low levels. The factor level of carriers should be measured to optimize perioperative management. Dur­ ing pregnancy, FVIII levels increase approximately two- to three­ fold in most carriers compared to nonpregnant women, whereas the FIX increase is less pronounced. After delivery, a rapid fall in the pregnancy-induced rise of maternal clotting factor levels occurs, resulting in increased risk for postpartum hemorrhage that can be prevented by infusion of factor concentrate to levels of 50–70% for 3 days for vaginal delivery and up to 5 days for cesarean delivery. In mild cases, the use of DDAVP and/or antifibrinolytic drugs is recommended. PART 4 Oncology and Hematology ■ ■FACTOR XI DEFICIENCY FXI deficiency, also known as hemophilia C, is a rare autosomal bleed­ ing disorder that occurs at a frequency of one in a million. However, it is highly prevalent among Ashkenazi and Iraqi Jewish populations, reaching a frequency of 6% heterozygotes and 0.1–0.3% homozygotes. More than 65 mutations in the FXI gene have been reported, whereas fewer mutations (two to three) are found among affected Jewish populations. Normal FXI clotting activity levels range from 70–150 U/dL. Levels vary depending on the presence of heterozygous, homozygous, or dou­ ble heterozygous mutations with levels <1 U/dL seen in the latter two. Patients with FXI levels <10% of normal have a high risk of bleeding, but the phenotype does not always correlate with FXI clotting activity. The family history is informative, with the bleeding risk based on bleed­ ing in kindreds. Clinically, spontaneous bleeding is rare, but mucocu­ taneous bleeding such as bruises, gum bleeding, epistaxis, hematuria, and menorrhagia are common, especially following trauma. This hem­ orrhagic phenotype suggests that tissues rich in fibrinolytic activity are more susceptible to FXI deficiency. Postoperative bleeding is common but not always present, even among patients with very low FXI levels. FXI replacement is indicated in patients with severe disease for major surgical procedures. A negative history of bleeding complica­ tions following invasive procedures does not exclude the possibility of an increased risk for hemorrhage. TREATMENT Factor XI Deficiency Sources of FXI are limited to FFP in the United States, whereas a plasma-derived FXI concentrate is available in other countries. FFP at doses of 15–20 mL/kg to increase levels by 10–20% can be given every other day in the setting of bleeding or major surgery as FXI has a half-life of 40–70 h. Antifibrinolytic drugs can be used for minor bleeds and as adjunctive treatment with FXI replace­ ment with the exception of genitourinary tract bleeding. The development of an FXI inhibitor can be seen in 10% of severely FXI-deficient patients. Although inhibitors are not associated with spontaneous bleeding, bleeding with surgery or trauma can be severe; treatment with PCC/aPCC or recombinant activated FVII is effective. Data for use of a single very low dose of recombinant activated FVII (10–15 μg/kg) and an antifibrinolytic agent before surgery in patients with severe FXI deficiency are good, avoiding the need for plasma products. RARE BLEEDING DISORDERS Inherited disorders resulting from deficiencies of clotting factors other than FVIII, FIX, and FXI (Table 121-1) occur infrequently. Bleeding manifestations vary from generally asymptomatic as with dysfibrino­ genemia or FVII deficiency to life-threatening as with FX or FXIII deficiency. In contrast to hemophilia, hemarthroses are rare, but bleed­ ing in the mucosal tract or after umbilical cord clamping is common. Individuals heterozygous for plasma coagulation deficiencies are often asymptomatic. The laboratory assessment for the specific deficient factor following screening with general coagulation tests (Table 121-1) identifies the diagnosis. Replacement therapy using FFP or PCCs for deficiencies provides adequate hemostasis for bleeds or prophylactic treatment, although specific concentrates for FX and fibrinogen are available. Cryopre­ cipitate or FXIII concentrate is needed for FXIII deficiency. FVII defi­ ciency, like FXI, has an increased prevalence in the Ashkenazi Jewish population and is best treated with recombinant FVIIa rather than FFP or PCCs depending on the severity of bleeding or type of surgery. It should be noted that deficiency of FXII is associated with significant prolongation of the aPTT but no bleeding phenotype. ■ ■FAMILIAL MULTIPLE COAGULATION DEFICIENCIES Several bleeding disorders are characterized by the inherited deficiency of more than one plasma coagulation factor. To date, the genetic defects in two of these diseases have been characterized, and they provide new insights into the regulation of hemostasis by gene-encoding proteins outside blood coagulation. Combined Deficiency of FV and FVIII  Patients with com­ bined FV and FVIII deficiency exhibit ~5% of residual clotting activ­ ity of each factor, yet have a mild bleeding tendency, often following trauma. A mutation in the lectin mannose binding 1 (LMAN1) gene, a mannose-binding protein localized in the Golgi apparatus that func­ tions as a chaperone for both FV and FVIII, is responsible. In other families, mutations in the multiple coagulation factor deficiency 2 (MCFD2) gene have been defined; this gene product forms a Ca2+- dependent complex with LMAN1, providing cofactor activity for intracellular mobilization of both FV and FVIII. Replacement therapy to control or prevent bleeding consists of FFP to maintain FV levels and DDAVP or FVIII concentrate to achieve FVIII levels of 20–40%. Alternatively, platelets, which contain FV, can also be used. Multiple Deficiencies of Vitamin K–Dependent Coagulation Factors  Two enzymes involved in vitamin K metabolism have been associated with combined deficiency of all vitamin K–dependent proteins, including the procoagulant proteins prothrombin (II), VII, IX, and X and the anticoagulant proteins C and S. Vitamin K, a fatsoluble vitamin, is a cofactor for carboxylation of the gamma carbon of the glutamic acid residues in the vitamin K–dependent factors, a critical step for calcium and phospholipid binding (Fig. 121-3). The enzymes γ-glutamylcarboxylase and epoxide reductase are critical for the metabolism and regeneration of vitamin K. Mutations in the genes encoding the γ-carboxylase (GGCX) or vitamin K epoxide reductase complex 1 (VKORC1) result in defective enzymes and thus in vita­ min K–dependent factors with reduced activity, varying from 1–30% Warfarin Epoxide reductase Vitamin K epoxide Vitamin K reduced Carboxylase γ-Carboxyglutamic acid Glutamic acid FIGURE 121-3  The vitamin K cycle. Vitamin K is a cofactor for the formation of γ-carboxyglutamic acid residues on coagulation proteins. Vitamin K–dependent γ-glutamylcarboxylase, the enzyme that catalyzes the vitamin K epoxide reductase, regenerates reduced vitamin K. Warfarin blocks the action of the reductase and competitively inhibits the effects of vitamin K. of normal. Patients can have mild to severe bleeding episodes present from birth. Some patients respond to oral vitamin K1 (5–20 mg/d) or parenteral vitamin K1 at doses of 5–20 mg/week. For severe bleeding, replacement therapy with PCC may be necessary. ■ ■DISSEMINATED INTRAVASCULAR COAGULATION In 2001, the International Society on Thrombosis and Haemostasis (ISTH) defined DIC as “an acquired syndrome characterized by the intravascular activation of coagulation with loss of localization aris­ ing from different causes that can originate from and cause damage to the microvasculature, which if sufficiently severe, can produce organ dysfunction.” Many disparate processes are associated with DIC (Table 121-2). The most common causes are bacterial sepsis, although viral and fungal sepsis can also cause DIC; trauma; obstetric causes such as abruptio placentae or amniotic fluid embolism; and malignant disor­ ders, especially mucin-producing adenocarcinomas and acute promy­ elocytic leukemia. Activation of inflammatory pathways in response to infectious pathogens results in increased expression of tissue factor, activation of neutrophils and monocytes with release of cytokines and development of neutrophil extracellular traps, and release of poly­ phosphates that engage in cross-talk with the coagulation system to cause thrombin generation; this process is known as thrombo-inflammation. Damage to vascular endothe­ lial cells results in the loss of their native antithrom­ botic properties; such damage especially occurs with sepsis and trauma. Systemic inflammatory response syndrome (SIRS) and cytokine storm are cytokinemediated exuberant inflammatory responses often in the setting of infection that are associated with increased mortality and DIC. Purpura fulminans is a severe form of DIC resulting in thrombosis of exten­ sive areas of the skin; it affects predominantly young children following viral or bacterial infection, partic­ ularly those with inherited or acquired hypercoagu­ lability due to deficiencies of the components of the protein C pathway. Neonates homozygous for protein C deficiency can develop neonatal purpura fulminans with or without thrombosis of large vessels. Red blood cell damage and hemolysis Ischemic tissue damage Failure of multiple organs The central mechanism of DIC is the uncontrolled generation of thrombin by multiple mechanisms (Fig. 121-4). Simultaneous disruption of the physi­ ologic anticoagulant mechanisms and abnormal fibrinolysis further accelerate the process. These abnormalities contribute to systemic fibrin deposi­ tion in small and midsize vessels. The duration and intensity of the fibrin deposition can compromise Vessel patency FDP D-dimer FIGURE 121-4  The pathophysiology of disseminated intravascular coagulation (DIC). Interactions between coagulation and fibrinolytic pathways result in bleeding and thrombosis in the microcirculation in patients with DIC. FDP, fibrin degradation product. TABLE 121-2  Common Clinical Causes of Disseminated Intravascular Coagulation SEPSIS IMMUNOLOGIC DISORDERS • Bacterial: Staphylococci, streptococci, • Acute hemolytic transfusion reaction • Organ or tissue transplant rejection • Immunotherapy • Graft-versus-host disease pneumococci, meningococci, gram-negative bacilli • Viral • Mycotic • Parasitic • Rickettsial TRAUMA AND TISSUE INJURY DRUGS • Brain injury (gunshot) • Extensive burns • Fat embolism • Rhabdomyolysis • Fibrinolytic agents • Aprotinin • Warfarin (especially in neonates with protein C deficiency) • Prothrombin complex concentrates • Recreational drugs (amphetamines) VASCULAR DISORDERS ENVENOMATION • Giant hemangiomas (Kasabach- • Snake • Insects CHAPTER 121 Merritt syndrome) • Large vessel aneurysms (e.g., aorta) OBSTETRICAL COMPLICATIONS LIVER DISEASE • Abruptio placentae • Amniotic fluid embolism • Dead fetus syndrome • Septic abortion • Fulminant hepatic failure • Cirrhosis • Fatty liver of pregnancy Coagulation Disorders CANCER MISCELLANEOUS • Adenocarcinoma (prostate, • Shock • Respiratory distress syndrome • Massive transfusion pancreas, etc.) • Hematologic malignancies (acute promyelocytic leukemia) the blood supply of many organs, especially the lung, kidney, liver, and brain, with consequent organ failure; for example, pulmonary microvascular thrombosis is a component of adult respiratory distress syndrome (ARDS). The sustained activation of coagulation and forma­ tion of fibrin can result in consumption of clotting factors and platelets, which in turn leads to systemic bleeding that can be aggravated by secondary hyperfibrinolysis that occurs in late stages of DIC. DIC Uncontrolled thrombin generation Fibrin deposits in the microcirculation Consumption of platelets and coagulation factors Secondary fibrinolysis Diffuse bleeding TABLE 121-3  International Society on Thrombosis and Haemostasis Criteria for Overt Disseminated Intravascular Congestion (DIC) PARAMETER VALUE POINTS Platelets >100,000 × 109/L >50–<100 × 109/L <50 × 109/L d-Dimera Normal Moderate increase Severe increase Prothrombin time (PT) prolonged <3 s 3–<6 s >6 s Fibrinogen >1 g/L <1 g/L Total Score   <5 Low-grade DIC >5 Overt DIC ad-Dimer assays are not standardized and have different ranges of normal. Check your institution range of normal to assess degree of increase. Note: A score of <5 suggests nonovert DIC/low-grade DIC and should be repeated every 1–2 days. A score of >5 suggests overt DIC; lab values should be repeated daily to assess critical changes. Not to be used in pregnant patients. PART 4 Oncology and Hematology Clinical manifestations of DIC are related to the magnitude of the imbalance of hemostasis, to the underlying disease, or to both. The most common clinical findings include petechiae, ecchymoses, and bleeding ranging from oozing from venipuncture sites to severe hemorrhage from the gastrointestinal tract, lung, or into the CNS. In chronic DIC, the bleeding symptoms are discrete and restricted to skin or mucosal surfaces. The hypercoagulability of DIC manifests as the occlusion of vessels in the microcirculation resulting in organ failure. Thrombosis of large vessels and cerebral embolism can also occur. Hemodynamic complications and shock are common among patients with acute DIC, due to the underlying disease, with mortality ranging from 30 to >80%. Making the diagnosis of DIC can be difficult. The ISTH has devel­ oped a validated scoring tool to aid in the diagnosis of overt DIC with a separate tool for pregnant women. It incorporates platelet count, d-dimer level, PT, and fibrinogen level, and assigns points for different levels of each with the aggregate score helping to make the diagnosis of DIC (Table 121-3). The peripheral smear should be assessed for schis­ tocytes. The laboratory diagnosis of DIC should prompt a search for the underlying disease if not already apparent. In critically ill patients, these tests should be repeated over a period of 6–8 h as patients can rapidly deteriorate. Chronic DIC  Low-grade, compensated DIC can occur in clinical situations including giant hemangioma, metastatic carcinoma, or late gestation fetal demise. Plasma levels of fibrin degradation product or d-dimers are elevated. aPTT, PT, and fibrinogen values are within the normal range or high. Mild thrombocytopenia or normal platelet counts are also common findings. Red cell fragmentation is often detected but at a lower degree than in acute DIC. Differential Diagnosis  Distinguishing between DIC and severe liver disease is challenging and requires serial measurements of the lab­ oratory parameters of DIC. Patients with severe liver disease manifest laboratory features including thrombocytopenia due to platelet seques­ tration, portal hypertension, or hypersplenism; decreased synthesis of coagulation factors and natural anticoagulants; and elevated levels of d-dimer. However, in contrast to DIC, these laboratory parameters in liver disease do not change rapidly. Although microangiopathic disorders such as immune thrombotic thrombocytopenic purpura present with acute onset accompanied by thrombocytopenia, red cell fragmentation, and multiorgan failure, the clinical presentation and laboratory findings including presence of an inhibitor to ADAMTS13 assist in diagnosis (Chap. 120). TREATMENT Disseminated Intravascular Coagulation The morbidity and mortality associated with DIC are primarily related to the underlying disease. Management of the underlying disease is required to control and eliminate DIC; however, support with platelets and coagulation factors may be needed until the incit­ ing cause is under control. Many patients with overt DIC are criti­ cally ill, usually requiring management in the intensive care unit to treat shock physiology and other manifestations of the underlying illness. MANAGEMENT OF HEMORRHAGIC SYMPTOMS Patients with active bleeding or at high risk of bleeding during inva­ sive procedures or after chemotherapy require transfusion support; however, transfusion solely to correct mildly to moderately abnor­ mal coagulation parameters is not indicated. Platelet transfusion for platelet counts <10,000–20,000/μL and replacement of fibrinogen and coagulation factors with FFP, cryoprecipitate, or fibrinogen concentrate as a source of fibrinogen are indicated with amounts determined by the degree of abnormal PT, aPTT, and fibrinogen levels, as well as severity of bleeding or bleeding risk with invasive procedures. For these situations, fibrinogen level should be main­ tained at >150 mg/dL and PT prolonged no more than 3 s above the upper limit of normal. Vitamin K should be given. Patients should be frequently monitored, and transfusion support adjusted as the patient’s condition changes and dictates. REPLACEMENT OF COAGULATION OR FIBRINOLYSIS INHIBITORS Anticoagulants such as heparin, concentrates of antithrombin and thrombomodulin, and antifibrinolytic drugs have all been tried in the treatment of DIC. Low doses of continuous-infusion heparin (5–10 U/kg per h) may be effective in patients with low-grade DIC associated with solid tumors, acute promyelocytic leukemia, or in a setting with recognized thrombosis. Heparin is also indicated for the treatment of purpura fulminans. In acute hemorrhagic DIC, the use of heparin is likely to aggravate bleeding. The use of heparin in patients with severe DIC, although demonstrating improved coagu­ lation parameters, is not associated with a survival benefit; profes­ sional society recommendations for use vary widely. Although the use of concentrates of the serine protease inhibitors, antithrombin and thrombomodulin, for sepsis demonstrated little efficacy in all treated patients, post hoc analyses of those with sepsis and con­ firmed DIC suggest a survival advantage and require further study. Activated protein C treatment for septic shock was withdrawn from the market years ago as findings in clinical practice did not replicate the mortality advantage seen in the clinical trial; impact on DIC was not evaluated. In patients who have DIC characterized by a primary hyperfi­ brinolytic state with concomitant severe bleeding, the administra­ tion of antifibrinolytics may be considered. However, concern for increasing the risk of thrombosis has led to consideration of con­ comitant use of heparin. Patients with acute promyelocytic leuke­ mia or those with chronic DIC associated with giant hemangiomas are among the few patients who may benefit from this therapy. ■ ■VITAMIN K DEFICIENCY Vitamin K–dependent proteins are a heterogeneous group, including clotting factor proteins and proteins found in bone, lung, kidney, and placenta. Vitamin K mediates posttranslational modification of gluta­ mate residues to γ-carboxylglutamate, which is necessary for calcium binding and proper assembly on phospholipid membranes (Fig. 121-3). Inherited mutations with decreased functional activity of the enzymes GGCX or VKORC1 (see above) result in bleeding disorders. Vitamin K in the diet is often limiting for the carboxylation reaction; thus, recycling of the vitamin K by these enzymes is essential to maintain normal levels of vitamin K–dependent proteins. In adults, severe vitamin K deficiency due to low dietary intake is rare but is common in association with the use of broad-spectrum antibiotics or with disease or surgical interventions that affect the ability of the intestinal tract to absorb vitamin K, through anatomic alterations or by changing the fat content of bile salts and pancreatic enzymes in the proximal small bowel. Chronic liver diseases such as primary biliary cirrhosis also deplete vitamin K stores. Neonatal vitamin K deficiency and the result­ ing hemorrhagic disease of the newborn have been almost entirely eliminated by routine administration of vitamin K to all neonates. Prolongation of PT values is the most common and earliest finding in vitamin K–deficient patients due to the short half-life of FVII and occurs before prolongation of the aPTT. Parenteral administration of 10 mg of vitamin K is sufficient to restore normal levels of clotting fac­ tor within 8–10 h. More rapid correction of the coagulopathy requires replacement with FFP or PCC, with the choice depending on patient intravascular volume status and need for rapidity of correction. The reversal of excessive anticoagulant therapy with vitamin K antagonists, such as warfarin, can be achieved by minimal doses of vitamin K (1 mg orally or by intravenous injection) for asymptomatic patients. This strategy can diminish the risk of bleeding while maintaining thera­ peutic anticoagulation for an underlying prothrombotic state. For emer­ gent reversal of warfarin in the setting of life-threatening bleeding or need for emergency surgery, use of 4F-PPC is the standard of care. In patients with underlying vascular disease, vascular trauma, atrial fibrillation, and other comorbidities, re-initiation of anticoagulation needs to be carefully considered to prevent subsequent thromboem­ bolic complications. ■ ■COAGULATION DISORDERS ASSOCIATED WITH LIVER FAILURE The liver is the site of synthesis and clearance of most procoagulant and natural anticoagulant proteins and of essential components of the fibrinolytic system. Acute liver failure is associated with a high risk of bleeding due to deficient synthesis of procoagulant factors and enhanced fibrinolysis; hepatologists refer to this as accelerated intra­ vascular coagulation and fibrinolysis (AICF). Thrombocytopenia is common in patients with liver disease and may be due to decreased thrombopoietin that is synthesized in the liver, congestive spleno­ megaly (hypersplenism), or immune-mediated shortened platelet life span (primary biliary cirrhosis). In addition, several anatomic abnor­ malities secondary to underlying liver disease further increase the risk of bleeding (Table 121-4). Dysfibrinogenemia is a relatively common finding in patients with liver disease due to impaired fibrin polymer­ ization. The development of DIC in patients with chronic liver disease is not uncommon and may enhance the risk for bleeding. Laboratory TABLE 121-4  Coagulation Disorders and Hemostasis in Liver Disease Bleeding Portal hypertension   Esophageal varices Thrombocytopenia   Splenomegaly   Chronic or acute DIC Decreased synthesis of clotting factors   Hepatocyte failure   Vitamin K deficiency Systemic fibrinolysis DIC Dysfibrinogenemia Thrombosis Decreased synthesis of coagulation inhibitors: protein C, protein S, antithrombin   Hepatocyte failure   Vitamin K deficiency (protein C, protein S) Failure to clear activated coagulation proteins (DIC) Dysfibrinogenemia Abbreviation: DIC, disseminated intravascular coagulation. evaluation is mandatory for an optimal therapeutic strategy, either to control ongoing bleeding or before invasive procedures. Typically, these patients present with prolonged PT, aPTT, and thrombin time (TT) depending on the degree of liver damage, thrombocytopenia, and normal or slight increase in d-dimer. Fibrinogen levels are low only in fulminant hepatitis, decompensated cirrhosis, advanced liver disease, or in the presence of DIC. The presence of prolonged TT and normal fibrinogen and d-dimer levels suggests dysfibrinogenemia. FVIII levels are often normal or elevated in patients with liver failure, and decreased levels suggest superimposed DIC. FV is only synthesized in the hepatocyte and is not a vitamin K–dependent protein; therefore, reduced levels of FV may be an indicator of liver failure. Normal levels of FV and low levels of FVII suggest vitamin K deficiency. Vitamin K levels may be reduced in patients with liver failure due to compromised storage in hepatocellular disease, changes in bile acids, or cholestasis that can diminish the absorption of vitamin K. Replacement with intra­ venous vitamin K may improve hemostasis. Patients with chronic stable liver disease are now recognized to have rebalanced hemostasis with simultaneous changes in both pro­ coagulant and anticoagulant proteins. Although traditional clinical laboratory tests may suggest increased bleeding risk, these patients in fact do not have spontaneous bleeding and often do not need treat­ ment for minor to moderate bleeding risk procedures. If the patient is bleeding, treatment with FFP was the standard approach to correct­ ing hemostasis in patients with acute liver failure; however, the use of 4F-PCC is now favored due to lower volume, less increase in portal pressure, reduced risk of circulatory overload, and other complications associated with FFP transfusion. As in any clinical situation, treatment should not be given simply to correct laboratory abnormalities in a patient who is not bleeding or with no need for invasive procedures. Platelet concentrates are indicated when platelet counts are <10,000– 20,000/μL to control bleeding or immediately before an invasive pro­ cedure if counts are <50,000/μL. Cryoprecipitate is indicated only when fibrinogen levels are <100–150 mg/mL unless the patient is bleeding, in which case a higher target is used. The use of antifibrinolytic drugs as adjuncts to control bleeding in patients with liver failure is not thought to result in an increased risk of thrombosis; however, their impact on acute thrombosis propagation is not well studied. CHAPTER 121 Coagulation Disorders Liver Disease and Thromboembolism  Bleeding in patients with stable liver disease is often mild or even asymptomatic. However, as the disease progresses, the hemostatic balance is precarious and easily disturbed; comorbid complications such as infections and renal failure can rapidly upset this balance (Fig. 121-5). Past assumptions based on abnormal coagulation tests have been that patients with liver disease have a decreased risk of thrombosis; however, multiple factors contribute to hypercoagulability, including decreased levels of the natural anticoagulant proteins S and C, as well as endothelial cell changes and hemodynamic changes that result in stasis such that portal vein thrombosis is common. Patients with liver disease can also develop deep-vein thrombosis and pulmonary embolism; those with cirrhosis appear to have a 1.5- to 2-fold increase in the rate of venous thromboembolism (VTE). Patients with compensated cirrhosis do not appear to have increased bleeding with the use of VTE prophylaxis or even therapeutic dose heparin to treat acute portal vein thrombosis when carefully managed. In the outpatient setting, warfarin is avoided, but low-molecular-weight heparin and direct oral anticoagulants have been safely used to treat thrombosis. Acquired Inhibitors of Coagulation Factors  An acquired inhibitor is an immune-mediated disease characterized by the pres­ ence of an autoantibody against a specific clotting factor. Almost half of patients with an acquired factor inhibitor will have an underlying autoimmune or immunoproliferative disorder, have a malignancy, or be peripartum. FVIII is the most common target of antibody forma­ tion and is often referred to as acquired hemophilia A, but inhibitors to prothrombin (FII), FV, FIX, FX, and FXI are also reported. Acquired inhibitor to FVIII occurs predominantly in older adults (median age of 60 years) but occasionally in pregnant or postpartum women with BLEEDING THROMBOSIS Thrombocytopenia Increased levels of VWF Abnormal platelet function Primary hemostasis Low production of thrombopoietin Decreased levels of ADAMTS-13 Increased production nitric oxide and prostacyclin EQUILIBRIUM Reduced levels of factors II, V, VII, IX, X, XI Elevated levels of FVIII Coagulation Decreased levels of protein C, protein S, antithrombin and heparin cofactor II Vitamin K deficiency Disfibrinogenemia Inherited thrombophilia Low levels of α2-antiplasmin, FXIII and TAFI Fibrinolysis Low levels of plasminogen Elevated level of t-PA Hemodynamic changes (reduced portal blood flow) Comorbidity PART 4 Oncology and Hematology Vascular damage (esophageal varices) Portal hypertension; bacterial infection and renal diseases FIGURE 121-5  Balance of hemostasis in liver disease. TAFI, thrombin-activated fibrinolytic inhibitor; t-PA, tissue plasminogen activator; VWF, von Willebrand factor. no previous history of bleeding. Bleeding episodes occur commonly in soft tissues, the gastrointestinal or urinary tracts, and skin. In con­ trast to congenital hemophilia, hemarthrosis is rare in these patients. Retroperitoneal hemorrhages and other life-threatening bleeding may appear suddenly. The overall mortality in untreated patients ranges from 8–22%, and most deaths occur within the first few weeks after presentation. The diagnosis is based on the prolonged aPTT with normal PT and TT and a mixing study that does not correct with normal pooled plasma. The Bethesda assay using factor-specific defi­ cient plasma as performed for inhibitor detection in hemophilia will confirm the diagnosis. Treatment of acquired inhibitors of coagulation factors requires control of bleeding and eradication of the inhibitor. Many patients can have life-threatening bleeding. The use of activated “bypass products” such as aPCC or recombinant FVIIa is required. The use of recombinant porcine FVIII can be effective for acquired inhibitors of FVIII. The use of emicizumab to treat acquired FVIII inhibitors has been reported, and trials in this population are underway in Europe. In contrast to inhibitors in patients with congenital factor defi­ ciencies, acquired inhibitors are typically responsive to immune suppression, and treatment should be initiated early for most cases. High-dose intravenous γ-globulin and anti-CD20 monoclonal anti­ body are reported to be effective in patients with autoantibodies to FVIII; however, no firm evidence confirms that these alternatives are superior to the first line of immunosuppressive drugs (glucocorticoids and cyclophosphamide), effective in 70% of patients. Relapse of an inhibitor to FVIII is relatively common (up to 20%) within the first 6 months following withdrawal of immunosuppression; patients should be followed up regularly for relapse. Topical plasma-derived bovine and human thrombin are commonly used during major cardiovascular, thoracic, neurologic, and pelvic surgeries as well as in trauma patients with extensive burns. Antibody formation to the xenoantigen or its contaminant (bovine clotting protein) has the potential to cross-react with human clotting factors, particularly FV and thrombin, and can result in bleeding that can be life-threatening. The development of antibodies to FV with the use of topical preparations of recombinant human thrombin has also been reported. The clinical diagnosis of these acquired coagulopathies is rare but is often complicated by the fact that the bleeding episodes may be detectable during or imme­ diately following major surgery and could be assumed to be due to the procedure itself. Primary hemostasis The risk of developing a cross-reacting antibody is increased by repeated exposure to topical thrombin preparations. Thus, a careful medical history of previous surgical interventions that may have occurred even decades earlier is critical to assessing risk. Coagulation The laboratory abnormalities include a combined prolongation of the aPTT and PT that often fails to improve by transfu­ sion of FFP and vitamin K, and a mixing study that does not correct with normal pooled plasma. The specificity of the anti­ body is determined by the measurement of the residual activity of human FV or other suspected human clotting factor. No assays specific for bovine thrombin coagulopathy are commercially available. Fibrinolysis No treatment guidelines have been estab­ lished. Platelet transfusions have been used as a source of FV replacement for patients with FV inhibitors. FFP and vitamin K sup­ plementation may function as co-adjuvants rather than as effective treatments for the coagulopathy itself. Experience with recom­ binant FVIIa as a bypass agent is limited, and outcomes have been generally poor. Specific treatments to eradicate the antibodies based on immunosup­ pression with glucocorticoids, intravenous immunoglobulin, or serial plasmapheresis have been sporadically reported. Patients should be advised to avoid any topical thrombin sealant in the future. The presence of lupus anticoagulant can be associated with venous or arterial thrombotic disease. However, bleeding has also been reported rarely with lupus anticoagulants due to antibodies to prothrombin, resulting in hypoprothrombinemia. Both disorders show a prolonged aPTT that does not correct on mixing. To distinguish acquired inhibi­ tors from lupus anticoagulant, note that the dilute Russell viper venom time (dRVVT) and the hexagonal-phase phospholipids test will be negative in patients with an acquired inhibitor and positive in patients with lupus anticoagulants. Moreover, lupus anticoagulant interferes with the clotting activity of many factors (FVIII, FIX, FXI, FXII), which can be assessed in the clinical laboratory; acquired inhibitors are spe­ cific to a single factor. Acknowledgment Valder Arruda and Katherine High wrote this chapter in prior editions and some material from their chapter is included here. ■ ■FURTHER READING Kitazawa T, Shima M: Emicizumab, a humanized bispecific antibody to coagulation factors IXa and X with a factor VIIIa-cofactor activity. Int J Hematol 111:20, 2020. Levi M, Scully M: How I treat disseminated intravascular coagula­ tion. Blood 131:845, 2018. Menegatti M et al: Management of rare acquired bleeding disorders. Hematology Am Soc Hematol Educ Program 2019:80, 2019. Pipe S et al: Delivery of gene therapy in haemophilia treatment centres in the United States: Practical aspects of preparedness and implemen­ tation. Haemophilia 29:1430, 2023. Roberts LN: How to manage hemostasis in patients with liver disease during interventions. Hematology Am Soc Hematol Educ Program 2023:274, 2023. Srivastava A et al: WFH guidelines for the management of hemo­ philia, 3rd edition. Haemophilia 26:1, 2020. # 53 - 122 Arterial and Venous Thrombosis ### 122 Arterial and Venous Thrombosis Jane E. Freedman, Joseph Loscalzo Arterial and Venous Thrombosis OVERVIEW OF THROMBOSIS ■ ■GENERAL OVERVIEW Thrombosis is hemostasis “at the wrong place and at the wrong time” (MacFarlane). The obstruction of blood flow due to the formation of thrombus may result in tissue anoxia and damage, and it is a major cause of morbidity and mortality in a wide range of arterial and venous diseases and patient populations. As reported in 2020, 655,000 Americans die from heart disease each year or about 1 in 4 deaths. In 2020, coronary disease killed 382,820 people and stroke killed 160,747 in the United States with approximately 805,000 suffering from heart attacks and 795,000 having strokes. It is estimated that as many as 600,000 people each year have a pulmonary embolism or deep-venous thrombotic event, and 60,000– 80,000 Americans die of these conditions annually. In the nondiseased state, physiologic hemostasis reflects a delicate interplay between fac­ tors that promote and inhibit blood clotting, favoring the former. This response is crucial as it prevents uncontrolled hemorrhage and exsan­ guination following injury. In specific settings, the same processes that regulate normal hemostasis can cause pathologic thrombosis, leading to arterial or venous occlusion. Importantly, many commonly used therapeutic interventions may also alter the thrombotic–hemostatic balance adversely. Hemostasis and thrombosis primarily involve the interplay among three factors: the vessel wall, coagulation and fibrinolytic proteins, and platelets. Many prevalent acute vascular diseases are due to thrombus formation within a vessel, including myocardial infarction, throm­ botic cerebrovascular events, and venous thrombosis. Although the end result is vessel occlusion and tissue ischemia, the pathophysiologic processes governing these pathologies have similarities as well as distinct differences. While many of the pathways regulating thrombus formation are similar to those that regulate hemo­ stasis, the processes triggering or per­ petuating thrombosis may be distinct and can vary in different clinical and genetic settings. In venous thrombosis, primary hypercoagulable states reflecting defects in the proteins governing coagulation and/or fibrinolysis or secondary hypercoagulable states involving abnormalities of blood vessels and blood flow or stasis lead to thrombosis. By contrast, arterial thrombo­ sis is highly dependent on the state of the vessel wall, the platelet, and factors related to blood flow. Endothelial cells Inactive platelets ARTERIAL THROMBOSIS ■ ■OVERVIEW OF ARTERIAL THROMBOSIS In arterial thrombosis, platelets and abnormalities of the vessel wall typically play a key role in vessel occlusion. Arterial thrombus forms via a series of sequential steps in which platelets adhere to the vessel wall, additional platelets are recruited, and thrombin is activated (Fig. 122-1). The regulation of platelet adhesion, activation, FIGURE 122-1  Platelet activation and thrombosis. Platelets circulate in an inactive form in the vasculature. Damage to the endothelium and/or external stimuli activate platelets that adhere to the exposed subendothelial von Willebrand factor and collagen. This adhesion leads to activation of the platelet, shape change, and the synthesis and release of thromboxane (TxA2), serotonin (5-HT), and adenosine diphosphate (ADP). Platelet stimuli cause conformational change in the platelet integrin glycoprotein (GP) IIb/IIIa receptor, leading to the high-affinity binding of fibrinogen and the formation of a stable platelet thrombus. aggregation, and recruitment will be described in detail below. In addi­ tion, while the primary function of platelets is regulation of hemostasis, our understanding of their role in other processes, such as immunity, metastasis, wound healing, and inflammation, continues to evolve. ■ ■ARTERIAL THROMBOSIS AND VASCULAR DISEASE Arterial thrombosis is a major cause of morbidity and mortality both in the United States and, increasingly, worldwide. Although the rates have declined in the United States, the overall burden remains high. Overall, in 2020, heart disease was estimated to cause about 1 of every 4 deaths in the United States. In addition to the 605,000 Americans who will have a new coronary event annually, an additional 200,000 myocardial infarctions occur in those with previous heart attacks. Although the rate of strokes has fallen, each year about 795,000 people experience a new or recurrent ischemic stroke. In 2018, about 1 in 6 deaths from cardiovascular disease were due to stroke in the United States. ■ ■THE PLATELET Many processes in platelets have parallels with other cell types, such as the presence of specific receptors and signaling pathways; however, unlike most cells, platelets lack a nucleus and are unable to adapt to changing biologic settings by altered gene transcription. Plate­ lets sustain limited protein synthetic capacity from megakaryocytederived and intracellularly transported messenger RNA (mRNA) and microRNA (miRNA). Most of the molecules needed to respond to various stimuli, however, are maintained in storage granules and mem­ brane compartments. CHAPTER 122 Platelets are disc-shaped, very small, anucleate cells (1–5 μm in diam­ eter) that circulate in the blood at concentrations of 200–400,000/μL, with an average life span of 7–10 days. Platelets are derived from megakaryocytes, polyploidal hematopoietic cells found in the bone marrow. The primary regulator of platelet formation is thrombopoietin (TPO). The precise mechanism by which megakaryocytes produce and release fully formed platelets is unclear, but the process likely involves formation of proplatelets, pseudopod-like structures generated by the Arterial and Venous Thrombosis Active platelets Fibrinogen GPIIb-IIIa TxA2 ADP 5-HT Active GPIIb-IIIa Collagen von Willebrand factor evagination of the cytoplasm from which platelets bud. After release into the circulation, (young, large) platelets may continue to divide. Platelet granules are synthesized in megakaryocytes before thrombo­ poiesis and contain an array of prothrombotic, proinflammatory, and antimicrobial mediators. The two major types of platelet granules, alpha and dense, are distinguished by their size, abundance, and con­ tent. Alpha-granules contain soluble coagulation proteins, adhesion molecules, growth factors, integrins, cytokines, and inflammatory modulators. Platelet dense-granules are smaller than alpha-granules and less abundant. Whereas alpha-granules contain proteins that may be more important in the inflammatory response, dense-granules contain high concentrations of small molecules, including adenosine diphosphate (ADP) and serotonin, that influence platelet aggregation and other related vascular processes, such as vasomotor tone. Platelet Adhesion  (See Fig. 122-1) The formation of a thrombus is initiated by the adherence of platelets to the damaged vessel wall. Damage exposes subendothelial components responsible for triggering platelet reactivity, including collagen, von Willebrand factor, fibronec­ tin, and other adhesive proteins, such as vitronectin and thrombos­ pondin. The hemostatic response may vary, depending on the extent of damage, the specific proteins exposed, and flow conditions. Certain proteins are expressed on the platelet surface that subsequently regulate collagen-induced platelet adhesion, particularly under flow conditions, and include glycoprotein (GP) IV, GPVI, and the integrin α2β1. The platelet GPIb-IX-V complex adhesive receptor is central both to platelet adhesion and to the initiation of platelet activation. Damage to the blood vessel wall exposes subendothelial von Willebrand factor and collagen to the circulating blood. The GPIb-IX-V complex binds to the exposed von Willebrand factor, causing platelets to adhere (Fig. 122-1). In addi­ tion, the engagement of the GPIb-IX-V complex with ligand induces signaling pathways that lead to platelet activation. von Willebrand fac­ tor–bound GPIb-IX-V promotes a calcium-dependent conformational change in the GPIIb/IIIa receptor, transforming it from an inactive lowaffinity state to an active high-affinity receptor for fibrinogen. PART 4 Oncology and Hematology Platelet Activation  The activation of platelets is controlled by a variety of surface receptors that regulate various functions in the acti­ vation process. Platelet receptors control many distinct processes and are stimulated by a wide variety of agonists and adhesive proteins that result in variable degrees of activation. In general terms, the stimula­ tion of platelet receptors triggers two specific processes: (1) activation of internal signaling pathways that lead to further platelet activation and granule release, and (2) the capacity of the platelet to bind to other adhesive proteins/platelets. Both of these processes contribute to the formation of a thrombus. Stimulation of nonthrombotic receptors results in platelet adhesion or interaction with other vascular cells, including endothelial cells, neutrophils, and mononuclear cells. Many families and subfamilies of receptors are found on platelets that regulate a variety of platelet functions. These include the seven transmembrane receptor family, which is the main agonist-stimulated receptor family. Several seven transmembrane receptors are found on platelets, including the ADP receptors, prostaglandin receptors, lipid receptors, and chemokine receptors. Receptors for thrombin comprise the major seven transmembrane receptors found on platelets. Among this last group, the first identified was the protease activation receptor 1 (PAR1). The PAR class of receptors has a distinct mechanism of acti­ vation that involves specific cleavage of the N-terminus by thrombin, which, in turn, acts as a ligand for the receptor. Other PAR receptors are present on platelets, including PAR2 (not activated by thrombin) and PAR4. Adenosine receptors are responsible for transduction of ADPinduced signaling events, which are initiated by the binding of ADP to purinergic receptors on the platelet surface. There are several distinct ADP receptors, classified as P2X1, P2Y1, and P2Y12. The activation of both the P2Y12 and P2Y1 receptors is essential for ADP-induced platelet aggregation. The thienopyridine derivatives, clopidogrel and prasugrel, are clinically used inhibitors of ADP-induced platelet aggregation. Platelet Aggregation  Activation of platelets results in a rapid series of signal transduction events, including tyrosine kinase, serine/ threonine kinase, and lipid kinase activation. In unstimulated platelets, the major platelet integrin GPIIb/IIIa is maintained in an inactive con­ formation and functions as a low-affinity adhesion receptor for fibrino­ gen. This integrin is unique as it is only expressed on platelets. After stimulation, the interaction between fibrinogen and GPIIb/IIIa forms intercellular connections between platelets, leading to the formation of a platelet aggregate (Fig. 122-1). A calcium-sensitive conformational change in the extracellular domain of GPIIb/IIIa enables the highaffinity binding of soluble plasma fibrinogen as a result of a complex network of inside-out signaling events. The GPIIb/IIIa receptor serves as a bidirectional conduit with GPIIb/IIIa-mediated signaling (outsidein signaling) occurring immediately after the binding of fibrinogen. This binding interaction leads to additional intracellular signaling that further stabilizes the platelet aggregate and transforms platelet aggrega­ tion from a reversible to an irreversible process (inside-out signaling). ■ ■THE ROLE OF PLATELETS AND THROMBOSIS IN INFLAMMATION Inflammation plays an important role during the acute thrombotic phase of acute coronary and other vascular occlusive syndromes. In the setting of acute upper respiratory infections, people are at higher risk of myocardial infarction and thrombotic stroke. Patients with acute coro­ nary syndromes have not only increased interactions between platelets (homotypic aggregates) but also increased interactions between plate­ lets and leukocytes (heterotypic aggregates) detectable in circulating blood. These latter aggregates form when platelets are activated, often directly by pathogens, and adhere to circulating leukocytes as part of their contribution to the immune process. Platelets bind via P-selectin (CD62P) expressed on the surface of activated platelets to the leukocyte receptor, P-selectin glycoprotein ligand 1 (PSGL-1). This association leads to increased expression of CD11b/CD18 (Mac-1) on leukocytes, which amplifies immunity but may also support further interactions with platelets partially via bivalent fibrinogen linking this integrin with its platelet surface counterpart, GPIIb/IIIa. Platelet surface P-selectin also induces the expression of tissue factor on monocytes, which pro­ motes fibrin formation. In addition to platelet–monocyte aggregates, the immunomodu­ lator, soluble CD40 ligand (CD40L or CD154), also reflects a link between thrombosis and inflammation. The CD40 ligand is a trimeric transmembrane protein of the tumor necrosis factor family and, with its receptor CD40, is an important contributor to the inflammatory process, leading both to thrombosis and atherosclerosis. While many immunologic and vascular cells have been found to express CD40 and/ or CD40 ligand, in platelets, CD40 ligand is rapidly translocated to the surface after stimulation and is upregulated in the newly formed thrombus. The surface-expressed CD40 ligand is cleaved from the platelet to generate a soluble fragment (soluble CD40 ligand). Links have also been established among platelets, infection, immu­ nity, and inflammation. Bacterial and viral infections are associated with a transient increase in the risk of acute thrombotic events, such as acute myocardial infarction and stroke. In addition, platelets con­ tribute significantly to the pathophysiology and high mortality rates of sepsis. The expression, functionality, and signaling pathways of Toll-like receptors (TLRs) have been established in platelets. Stimula­ tion of platelet TLR2, TLR3, and TLR4 directly and indirectly activates the platelet’s thrombotic and inflammatory responses, and live bacteria induce a proinflammatory response in platelets in a TLR2-dependent manner, suggesting a mechanism by which specific bacteria and bacte­ rial components can directly activate platelet-dependent thrombosis. Additionally, viruses, such as SARS-CoV-2, HIV, hepatitis C virus, and Dengue, are also known to elevate thrombosis; recently, platelets have been shown to regulate immune responses to viruses via receptors TLR7 and TLR8. Risk Factors for Arterial Thrombosis  In addition to immune burden, various factors increase the risk of developing arterial thrombo­ sis. Classically, the cardiovascular-dependent risk factors implicated in thrombosis have been hypertension, high levels of low-density lipopro­ tein cholesterol, and smoking. However, diabetes, pregnancy, age, and chemotherapeutic agents may also contribute to arterial thrombosis. Stillbirth and loss of multiple pregnancies may increase the risk of isch­ emic stroke and myocardial infarction, as does hormonal replacement therapy. Systemic lupus erythematosus and rheumatoid arthritis are now well-recognized risks for thrombosis, and the former, in particu­ lar, may contribute in the pediatric population. The antiphospholipid syndrome is also another widely recognized autoimmune prothrom­ botic risk for arterial (and venous) thrombosis. ■ ■GENETICS OF ARTERIAL THROMBOSIS Some studies have associated arterial thrombosis with genetic variants (Table 122-1A); however, the associations have been weak and not consistently confirmed in larger series. Platelet count and mean platelet volume have been studied by genome-wide association studies (GWAS), and this approach identified signals located to noncoding regions. Of 15 quantitative trait loci associated with mean platelet volume and platelet count, one located at 12q24 is also a risk locus for coronary artery disease. In the area of genetic variability and platelet function, studies have primarily dealt with pharmacogenetics, the field of pharmacology dealing with the interindividual variability in drug response based on genetic determinants (Table 122-2). This focus has been driven by the wide variability among individuals in terms of response to anti­ thrombotic drugs and the lack of a common explanation for this vari­ ance. The best described is the issue of “aspirin resistance,” although heterogeneity for other antithrombotics (e.g., clopidogrel) has also TABLE 122-1  Heritable Causes of Arterial and Venous Thrombosis A. Arterial Thrombosis Platelet Receptors   β3 and α2 integrins   Pl A2 polymorphism   Fc(gamma)RIIA   GPIV T13254C polymorphism   GPIb   Thrombin receptor PAR1-5061 → D Redox Enzymes   Plasma glutathione peroxidase, GPx3, promoter haplotype H2   H2 promoter haplotype   Endothelial nitric oxide synthase   –786T/C, –922A/G, –1468T/A   Paraoxonase   –107T allele, 192R allele Homocysteine   Cystathionine β-synthase 833T → C   5,10-Methylene tetrahydrofolate reductase (MTHFR) 677C → T B. Venous Thrombosis Procoagulant Proteins   Fibrinogen   –455G/A, –854G/A   Prothrombin (20210G → A) Protein C Anticoagulant Pathway   Factor V Leiden: 1691G → A (Arg506Gln)   Thrombomodulin 1481C →T (Ala455Val) Fibrinolytic Proteins with Known Polymorphisms   Tissue plasminogen activator (tPA)   7351C/T, 20 099T/C in exon 6, 27 445T/A in intron 10   Plasminogen activator inhibitor (PAI-1)   4G/5G insertion/deletion polymorphism at position –675 Homocysteine   Cystathionine β-synthase 833T → C   5,10-MTHFR 677C → T TABLE 122-2  Genetic Variation and Pharmacogenetic Responses to Platelet Inhibitors POTENTIAL GENE ALTERED TARGET THERAPEUTIC CLASS SPECIFIC DRUG P2Y1 and P2Y12 CYP2C19, CYP3A4, CYP3A5 ADP receptor inhibitors Clopidogrel, prasugrel COX1, COX2 Cyclooxygenase inhibitors Aspirin PlA1/A2 Receptor inhibitors Abciximab, eptifibatide, tirofiban INTB3, GPIbA Glycoprotein IIb-IIIa receptor inhibitors   been extensively examined. Primarily, platelet-dependent genetic determinants have been defined at the level of (1) drug effect, (2) drug compliance, and (3) drug metabolism. Many candidate platelet genes have been studied for their interaction with antiplatelet and antithrom­ botic agents. Many patients have an inadequate response to the inhibitory effects of aspirin. Heritable factors contribute to the variability; however, ex vivo tests of residual platelet responsiveness after aspirin administra­ tion have not provided firm evidence for a pharmacogenetic interac­ tion between aspirin and COX1 or other relevant platelet receptors. As such, currently there is no clinical indication for genotyping to opti­ mize aspirin’s antiplatelet efficiency. For the platelet P2Y12 receptor inhibitor clopidogrel, additional data suggest that genetics may affect the drug’s responsiveness and utility. The responsible genetic variant appears not to be the expected P2Y12 receptor but an enzyme respon­ sible for drug metabolism. Clopidogrel is a prodrug, and liver metabo­ lism by specific cytochrome P450 enzymes is required for activation. The genes encoding the CYP-dependent oxidative steps are polymor­ phic, and carriers of specific alleles of the CYP2C19 and CYP3A4 loci have increased platelet aggregability. Increased platelet activity has also been specifically associated with the CYP2C19*2 allele, which causes loss of platelet function in select patients. Because these are common genetic variants, this observation has been shown to be clinically relevant in large studies. In summary, although the loss-of-function polymorphisms in CYP2C19 is the strongest individual variable affect­ ing pharmacokinetics and antiplatelet response to clopidogrel, it only accounts for 5–12% of the variability in ADP-induced platelet aggre­ gation by clopidogrel. In addition, genetic variables do not appear to contribute significantly to the clinical outcomes of patients treated with the P2Y12 receptor antagonists prasugrel or ticagrelor. CHAPTER 122 Arterial and Venous Thrombosis VENOUS THROMBOSIS ■ ■OVERVIEW OF VENOUS THROMBOSIS Coagulation is the process by which thrombin is activated and soluble plasma fibrinogen is converted into insoluble fibrin. These steps account for both normal hemostasis and the pathophysiologic processes influencing the development of venous thrombosis. The primary forms of venous thrombosis are deep-vein thrombosis (DVT) in the extremities and the subsequent embolization to the lungs (pul­ monary embolism), referred to together as venous thromboembolic disease (VTE). Although the majority of venous thromboembolic events occur as pulmonary embolism or DVT of the lower extremities, up to 10% of events may occur in other vascular locations. Venous thrombosis has both heritable causes (Table 122-1B) and acquired causes (Table 122-3). ■ ■DEEP-VENOUS THROMBOSIS AND PULMONARY EMBOLISM It is estimated that DVT or pulmonary embolism (PE) occurs in ∼1–2 individuals per 1000 each year, resulting in 300,000–600,000 new cases of venous thromboembolism each year in the United States. Approxi­ mately, 60,000–80,000 deaths are attributed to DVT or PE annually. Of new cases, up to 30% of patients die within 30 days and one-fifth suffer TABLE 122-3  Acquired Causes of Venous Thrombosis Surgery Neurosurgery Major abdominal surgery Other Trauma Antiphospholipid syndrome Pregnancy Long-distance travel Obesity Oral contraceptives/hormone replacement Myeloproliferative disorders Polycythemia vera sudden death due to PE; 30% go on to develop recurrent VTE within 10 years. Data from the Atherosclerosis Risk in Communities (ARIC) study reported a 9% 28-day fatality rate from DVT and a 15% fatality rate from PE. PE in the setting of cancer has a 25% fatality rate. The mean incidence of first DVT in the general population is 5 per 10,000 person-years; the incidence is similar in males and females when adjusting for factors related to reproduction and birth control and increases dramatically with age from 2–3 per 10,000 person-years at 30–49 years of age to 20 per 10,000 person-years at 70–79 years of age. PART 4 Oncology and Hematology ■ ■OVERVIEW OF THE COAGULATION CASCADE AND ITS ROLE IN VENOUS THROMBOSIS Coagulation is defined as the formation of fibrin by a series of linked enzymatic reactions in which each reaction product converts the sub­ sequent inactive zymogen into an active serine protease (Fig. 122-2). This coordinated sequence is called the coagulation cascade and is a key mechanism for regulating hemostasis. Central to the function of the coagulation cascade is the principle of amplification: owing to a series of linked enzymatic reactions, a small stimulus can lead to much greater quantities of fibrin, the end product that prevents hemorrhage at the site of vascular injury. In addition to the known risk factors rel­ evant to hypercoagulopathy, stasis, and vascular dysfunction, newer areas of research have identi­ fied contributions from procoagulant micropar­ ticles, inflammatory cells, microvesicles, and fibrin structure. VII VIIa The coagulation cascade is primarily initiated by vascular injury exposing tissue factor to blood components (Fig. 122-2). Tissue factor may also be found in bloodborne cell-derived microparticles and, under pathophysiologic conditions, in leuko­ cytes or platelets. Plasma factor VII (FVII) is the ligand for and is activated (FVIIa) by binding to tis­ sue factor exposed at the site of vessel damage. The binding of FVII/VIIa to tissue factor activates the downstream conversion of factor X (FX) to active FX (FXa). In an alternative reaction, the FVII/ FVIIa–tissue factor complex initially converts FIX to FIXa, which then activates FX in conjunction with its cofactor factor VIII (FVIIIa). Thrombin can also activate factor XI (FXI) to active FXI (FXIa), which, in turn, can also activate FIX. FXa with its cofactor FVa converts prothrombin to thrombin, which then converts soluble plasma fibrinogen to insoluble fibrin, leading to clot or thrombus formation. Thrombin also activates FXIII to FXIIIa, a transglutaminase that covalently cross-links and stabilizes the fibrin clot. Formation of thrombi is affected by mechanisms governing fibrin structure and stability, including specific X Xa Thrombin Prothrombin FIGURE 122-2  Summary of the coagulation pathways. Specific coagulation factors (“a” indicates activated form) are responsible for the conversion of soluble plasma fibrinogen into insoluble fibrin. This process occurs via a series of linked reactions in which the enzymatically active product subsequently converts the downstream inactive protein into an active serine protease. In addition, the activation of thrombin leads to stimulation of platelets. HK, high-molecular-weight kininogen; PK, prekallikrein; TF, tissue factor. fibrinogen variants and how they alter fibrin formation, strength, and structure. Several antithrombotic factors also regulate coagulation; these include antithrombin, tissue factor pathway inhibitor (TFPI), heparin cofactor II, and protein C/protein S. Under normal conditions, these factors limit the production of thrombin to prevent the perpetuation of coagulation and thrombus formation. Typically, after the clot has caused occlusion at the damage site and begins to expand toward adja­ cent uninjured vessel segments, the anticoagulant reactions governed by the normal endothelium become pivotal in limiting the extent of this hemostatically protective clot. ■ ■RISK FACTORS FOR VENOUS THROMBOSIS An array of different factors contributes to the risk of VTE; it is notable that women and men of all ages, races, and ethnicities are at risk for VTE. The risk factors for venous thrombosis are primarily related to hypercoagulability, which can be genetic (Table 122-1) or acquired, or due to immobilization and venous stasis. Independent predictors for recurrence include increasing age, obesity, malignant neoplasm, and acute extremity paresis. It is estimated that 5–8% of the U.S. population has a genetic risk factor known to predispose to venous thrombosis. Often, multiple risk factors are present in a single individual. Sig­ nificant risk is incurred by major orthopedic, abdominal, or neurologic surgeries. Cancer patients have an approximately fourfold increased risk of VTE as compared with the general population, and cancer patients with VTE have reduced survival. Hospitalized patients have a greatly increased risk of venous thrombosis with risk factors (increased age, male, ethnicity) and comorbid conditions, including infection, renal disease, and weight loss. Community- or hospital-acquired infec­ tion is also associated with increased risk of VTE. Supportive of this risk, nearly 20% of hospitalized COVID-19 patients were noted to have coagulation abnormalities as well as increased PE, DVT, and peripheral thrombotic risk. Moderate risk is promoted by prolonged bedrest; certain types of cancer; pregnancy; hormone replacement therapy or oral contraceptive use; and other sedentary conditions, such as longdistance plane travel. It has been reported that the risk of developing a VTE event doubles after air travel lasting 4 h, although the absolute XII PK XI HK TF XIa IX Ca2+ XIa VIIa/TF IXa PL/Ca2+ Activated platelets VIII VIIIa PL/Ca2+ Va V Fibrinogen Fibrin # 54 - 123 Antiplatelet, Anticoagulant, and Fibrinolytic Drugs ### 123 Antiplatelet, Anticoagulant, and Fibrinolytic Drugs risk remains low (1 in 6000). The relative risk of VTE among pregnant or postpartum women is 4.3, and the overall incidence (absolute risk) is 199.7 per 100,000 woman-years. ■ ■GENETICS OF VENOUS THROMBOSIS (See Table 122-2) Less common causes of venous thrombosis are those due to genetic variants. These abnormalities include loss-of-function mutations of endogenous anticoagulants as well as gain-of-function mutations of procoagulant proteins. Heterozygous antithrombin defi­ ciency and homozygosity of the factor V Leiden mutation significantly increase the risk of venous thrombosis. While homozygous protein C or protein S deficiencies are rare and may lead to fatal purpura fulmi­ nans, heterozygous deficiencies are associated with a moderate risk of thrombosis. Activated protein C impairs coagulation by proteolytic degradation of FVa. Patients resistant to the activity of activated protein C may have a point mutation in the FV gene, a mutant denoted factor V Leiden. Mildly increased risk has been attributed to elevated levels of procoagulant factors, as well as low levels of tissue factor pathway inhibitor. Polymorphisms of methylene tetrahydrofolate reductase as well as hyperhomocysteinemia have been shown to be independent risk factors for venous thrombosis, as well as arterial vascular disease; however, many of the initial descriptions of genetic variants and their associations with thromboembolism are being questioned in larger, more contemporary studies. ■ ■FIBRINOLYSIS AND THROMBOSIS Specific abnormalities in the fibrinolytic system have been associated with enhanced thrombosis. Factors such as elevated levels of tissue plasminogen activator (tPA) and plasminogen activator inhibitor type 1 (PAI-1) have been associated with decreased fibrinolytic activity and an increased risk of arterial thrombotic disease. Specific genetic vari­ ants have been associated with decreased fibrinolytic activity, including the 4G/5G insertion/deletion polymorphism in the (plasminogen acti­ vator type 1) PAI-1 gene. Additionally, the 311-bp Alu insertion/dele­ tion in tPA’s intron 8 has been associated with enhanced thrombosis; however, genetic abnormalities have not been associated consistently with altered function or tPA levels, raising questions about the relevant pathophysiologic mechanism. Thrombin-activatable fibrinolysis inhib­ itor (TAFI) is a carboxypeptidase that regulates fibrinolysis; elevated plasma TAFI levels have been associated with an increased risk of both DVT and cardiovascular disease. The metabolic syndrome also is accompanied by altered fibrinolytic activity. This syndrome, which comprises abdominal fat (central obe­ sity), altered glucose and insulin metabolism, dyslipidemia, and hyper­ tension, has been associated with atherothrombosis. The mechanism for enhanced thrombosis appears to be due both to altered platelet function and to a procoagulant and hypofibrinolytic state. One of the most frequently documented prothrombotic abnormalities reported in this syndrome is an increase in plasma levels of PAI-1. In addition to contributing to platelet function, inflammation plays a role in both coagulation-dependent thrombus formation and throm­ bus resolution. Both polymorphonuclear neutrophils and monocytes/ macrophages contribute to multiple overlapping thrombotic func­ tions, including fibrinolysis, chemokine and cytokine production, and phagocytosis. THE DISTINCTION BETWEEN ARTERIAL AND VENOUS THROMBOSIS Although there is overlap, venous thrombosis and arterial thrombosis are initiated differently, and clot formation progresses by somewhat distinct pathways. In the setting of stasis or states of hypercoagulability, venous thrombosis is activated with the initiation of the coagulation cascade primarily due to exposure of tissue factor; this leads to the formation of thrombin and the subsequent conversion of fibrinogen to fibrin. In the artery, thrombin formation also occurs, but thrombosis is primarily promoted by the adhesion of platelets to an injured vessel and stimulated by exposed extracellular matrix (Figs. 122-1 and 122-2). There is wide variation in individual responses to vascular injury, an important determinant of which is the predisposition an individual has to arterial or venous thrombosis. This concept has been supported indirectly in prothrombotic animal models in which there is poor correlation between the propensity to develop venous versus arterial thrombosis. Despite considerable progress in elucidating the role of hyperco­ agulable states in VTE, the contribution of hypercoagulability to arte­ rial vascular disease is much less well understood. Although specific thrombophilic conditions, such as factor V Leiden and the prothrom­ bin G20210A mutation, are risk factors for DVT, PE, and other VTE events, their contribution to arterial thrombosis is less well defined. In fact, to the contrary, many of these thrombophilic factors have not been found to be clinically important risk factors for arterial thrombotic events, such as acute coronary syndromes. Clinically, although the pathophysiology is distinct, arterial and venous thrombosis do share common risk factors, including age, obesity, cigarette smoking, diabetes mellitus, arterial hypertension, hyperlipidemia, and metabolic syndrome. Select genetic variants, including those of the glutathione peroxidase-3 (GPx3) gene, have also been associated with arterial and venous thrombo-occlusive disease. Importantly, arterial and venous thrombosis may both be triggered by pathophysiologic stimuli responsible for activating inflammatory and oxidative pathways. CHAPTER 123 The diagnosis and treatment of ischemic heart disease are dis­ cussed in Chap. 284. Stroke diagnosis and management are dis­ cussed in Chap. 318. The diagnosis and management of DVT and PE are discussed in Chap. 290. ■ ■FURTHER READING Ackermann M et al: Pulmonary vascular endothelialitis, thrombosis, Antiplatelet, Anticoagulant, and Fibrinolytic Drugs and angiogenesis in Covid-19. N Engl J Med 383:120, 2020. Asmis L, Hellstern P: Thrombophilia testing: A systematic review. Clin Lab 69, 2023. Becattini C, Aegnelli G: Acute treatment of venous thromboembo­ lism. Blood 135:305, 2020. Engelmann B, Massberg S: Thrombosis as an intravascular effector of innate immunity. Nat Rev Immunol 13:34, 2013. Furie B, Furie BC: Mechanisms of thrombus formation. N Engl J Med 359:938, 2008. Kaiser R et al: Hemostasis without clot formation: How platelets guard the vasculature in inflammation, infection, and malignancy. Blood 142;1413, 2023. Koupenova M et al: Thrombosis and platelets: An update. Eur Heart J 38:785, 2017. Jeffrey I. Weitz Antiplatelet, Anticoagulant, and Fibrinolytic Drugs Thromboembolic disorders are major causes of morbidity and mortal­ ity. Thrombosis can occur in arteries or veins. Arterial thrombosis is the most common cause of acute myocardial infarction (MI), ischemic stroke, and limb gangrene. VTE encompasses DVT, which can lead to postthrombotic syndrome, and PE, which can be fatal or can result in chronic thromboembolic pulmonary hypertension. Most arterial thrombi are superimposed on disrupted atheroscle­ rotic plaque because plaque rupture exposes thrombogenic material in the core to the blood. This material then triggers platelet aggregation and fibrin formation, which results in the generation of a platelet-rich thrombus that can temporarily or permanently occlude blood flow. In contrast, venous thrombi rarely form at sites of obvious vascular Antithrombotic Drugs Anticoagulants Fibrinolytic agents Antiplatelet drugs FIGURE 123-1  Classification of antithrombotic drugs. disruption. Although they can develop after surgical trauma to veins or secondary to indwelling venous catheters, venous thrombi usually originate in the valve cusps of the deep veins of the calf or in the mus­ cular sinuses. Sluggish blood flow reduces the oxygen supply to the avascular valve cusps. Endothelial cells lining these valve cusps become activated and express adhesion molecules on their surface. Tissue factor– bearing leukocytes and microvesicles adhere to these activated cells and induce coagulation. DNA extruded from neutrophils forms neutrophil extracellular traps (NETs) that provide a scaffold that binds platelets, promotes their activation and aggregation, and activates factor XII. Local thrombus formation is exacerbated by reduced clearance of acti­ vated clotting factors because of impaired blood flow. If the thrombi extend from the calf veins into the popliteal and more proximal veins of the leg, thrombus fragments can dislodge, travel to the lungs, and produce PE. PART 4 Oncology and Hematology Arterial and venous thrombi are composed of platelets, fibrin, and trapped red blood cells, but the proportions differ. Arterial thrombi are rich in platelets because of the high shear in the injured arteries. In contrast, venous thrombi, which form under low shear conditions, contain relatively few platelets and are predominantly composed of fibrin and trapped red cells. Because of the predominance of platelets, arterial thrombi appear white, whereas venous thrombi are red in color, reflecting the trapped red cells. Antithrombotic drugs are used for the prevention and treatment of thrombosis. Targeting the components of thrombi, these agents include (1) antiplatelet drugs, (2) anticoagulants, and (3) fibrinolytic agents (Fig. 123-1). With the predominance of platelets in arterial thrombi, strategies to attenuate arterial thrombosis focus mainly on antiplatelet agents, although, in the acute setting, they may include anticoagulants and fibrinolytic agents. The addition of low-dose rivaroxaban, an oral factor Xa inhibitor, to dual-antiplatelet therapy reduces recurrent ischemic events and stent thrombosis in patients with acute coronary syndrome, whereas its addition to aspirin reduces the risk of major adverse coronary and limb events in patients with stable coronary or peripheral artery disease. These findings highlight the utility of combining low-dose anticoagulants with antiplatelet agents for secondary prevention in patients at high risk for recurrent atherothrombotic events. Anticoagulants are the mainstay of prevention and treatment of VTE because fibrin is the predominant component of venous thrombi. Antiplatelet drugs are less effective than anticoagulants in this setting because of the limited platelet content of venous thrombi. Fibrinolytic therapy is used in selected patients with VTE. For example, patients with massive PE can benefit from systemic or catheter-directed fibri­ nolytic therapy. Pharmaco-mechanical therapy is also used to restore blood flow in patients with extensive DVT involving the iliac and/or femoral veins. ANTIPLATELET DRUGS ■ ■ROLE OF PLATELETS IN ARTERIAL THROMBOSIS In healthy vasculature, circulating platelets are maintained in an inac­ tive state by nitric oxide (NO) and prostacyclin released by endothelial cells lining the blood vessels. In addition, endothelial cells also express CD39 on their surface, a membrane-associated ecto-adenosine diphos­ phatase (ADPase) that degrades ADP released from activated platelets. When the vessel wall is damaged, the release of these substances is impaired and the subendothelial matrix is exposed. Platelets adhere to exposed collagen via α2β1 and glycoprotein (Gp) V1 and to von Vascular Injury Exposure of collagen and VWF Tissue factor exposure Platelet adhesion and release Activation of coagulation Platelet recruitment and activation Thrombin generation Platelet aggregation Fibrin formation Platelet-fibrin thrombus FIGURE 123-2  Coordinated role of platelets and the coagulation system in thrombogenesis. Vascular injury simultaneously triggers platelet activation and aggregation and activation of the coagulation system. Platelet activation is initiated by exposure of subendothelial collagen and von Willebrand factor (VWF), onto which platelets adhere. Adherent platelets become activated and release ADP and thromboxane A2, platelet agonists that activate ambient platelets and recruit them to the site of injury. When platelets are activated, glycoprotein IIb/IIIa on their surface undergoes a conformational change that enables it to ligate fibrinogen and/or VWF and mediate platelet aggregation. Coagulation is triggered by tissue factor exposed at the site of injury. Tissue factor triggers thrombin generation. As a potent platelet agonist, thrombin amplifies platelet recruitment to the site of injury. Thrombin also converts fibrinogen to fibrin, and the fibrin strands then weave the platelet aggregates together to form a platelet/fibrin thrombus. Willebrand factor (VWF) via Gp Ibα—receptors that are constitutively expressed on the platelet surface. Adherent platelets undergo a change in shape, secrete ADP from their dense granules, and synthesize and release thromboxane A2. Released ADP and thromboxane A2, which are platelet agonists, activate ambient platelets and recruit them to the site of vascular injury (Fig. 123-2). Disruption of the vessel wall also exposes tissue factor–expressing cells to the blood. Tissue factor binds to factor VII and induces its activation, and the tissue factor–factor VIIa complex then initiates coagulation. Activated platelets potentiate coagulation by providing a negatively charged surface that binds clotting factors and supports the assembly of activation complexes that enhance thrombin generation. In addition to converting fibrinogen to fibrin, thrombin serves as a potent platelet agonist and recruits more platelets to the site of vascular injury. Thrombin also amplifies its generation by feedback activation of factors V, VIII, and XI and solidifies the fibrin network by activating factor XIII, which then cross-links the fibrin strands and renders them more resistant to degradation. When platelets are activated, Gp IIb/IIIa, the most abundant recep­ tor on the platelet surface, undergoes a conformational change that enables it to bind fibrinogen and, under high shear conditions, VWF. Divalent fibrinogen or multivalent VWF molecules bridge adjacent platelets together to form platelet aggregates. Fibrin strands, generated through the action of thrombin, then weave these aggregates together to form a platelet-rich fibrin clot. Antiplatelet drugs target various steps in this process. The com­ monly used antiplatelet drugs include aspirin, ADP receptor inhibitors, which include thienopyridines (clopidogrel and prasugrel) as well as ticagrelor and cangrelor, dipyridamole, Gp IIb/IIIa antagonists, and vorapaxar. ■ ■ASPIRIN The most widely used antiplatelet agent worldwide is aspirin. As a cheap and effective antiplatelet drug, aspirin serves as the foundation of most antiplatelet strategies. Mechanism of Action  Aspirin produces its antithrombotic effect by irreversibly acetylating and inhibiting platelet cyclooxygenase Plaque Disruption Tissue factor Collagen VWF Platelet adhesion and secretion Aspirin COX-1 Clopidogrel Prasugrel Ticagrelor Cangrelor TXA2 ADP Platelet recruitment and activation Thrombin Vorapaxar GpIIb/IIIa activation Abciximab Eptifibatide Tirofiban Platelet aggregation FIGURE 123-3  Site of action of antiplatelet drugs. Aspirin inhibits thromboxane A2 (TXA2) synthesis by irreversibly acetylating cyclooxygenase-1 (COX-1). Reduced TXA2 release attenuates platelet activation and recruitment to the site of vascular injury. Clopidogrel and prasugrel irreversibly block P2Y12, a key ADP receptor on the platelet surface; cangrelor and ticagrelor are reversible inhibitors of P2Y12. Abciximab, eptifibatide, and tirofiban inhibit the final common pathway of platelet aggregation by blocking fibrinogen and von Willebrand factor (VWF) binding to activated glycoprotein (Gp) IIb/IIIa. Vorapaxar inhibits thrombin-mediated platelet activation by targeting protease-activated receptor-1 (PAR-1), the major thrombin receptor on human platelets. (COX)-1 (Fig. 123-3), a critical enzyme in the biosynthesis of throm­ boxane A2. At high doses (~1 g/d), aspirin also inhibits COX-2, an inducible COX isoform found in endothelial cells and inflammatory cells. In endothelial cells, COX-2 initiates the synthesis of prostacyclin, a potent vasodilator and inhibitor of platelet aggregation. Indications  Aspirin is widely used for secondary prevention of car­ diovascular events in patients with established coronary artery, cerebral artery, or peripheral artery disease. Compared with placebo in this setting, aspirin produces a 25% reduction in the risk of cardiovascular death, MI, or stroke. Aspirin is no longer used routinely for primary prevention because recent studies suggest that the risk of gastrointesti­ nal and intracerebral hemorrhage outweigh the benefits. Consequently, aspirin is only recommended for primary cardiac prevention if the baseline cardiovascular risk is at least 1% per year over 10 years and patients are at low risk for bleeding. Dosages  Aspirin is usually administered at doses of 75–325 mg once daily. Higher doses of aspirin are not more effective than lower aspirin doses, and some analyses suggest reduced efficacy with higher doses. Because the side effects of aspirin are dose-related, daily aspirin doses of 75–100 mg are recommended for most indications. When rapid platelet inhibition is required, an initial aspirin dose of at least 160 mg should be given. Side Effects  The most common side effects are gastrointestinal and range from dyspepsia to erosive gastritis or peptic ulcers with bleeding and perforation. These side effects are dose related. Use of entericcoated or buffered aspirin in place of plain aspirin does not eliminate gastrointestinal side effects. The overall risk of major bleeding with aspirin is 1–3% per year. The risk of bleeding is increased two- to threefold when aspirin is given in conjunction with other antiplatelet drugs, such as clopidogrel or ticagrelor, or with anticoagulants, such as warfarin. When dual or triple therapy is prescribed, low-dose aspirin should be given (75–100 mg daily). Eradication of Helicobacter pylori infection and administration of proton pump inhibitors may reduce the risk of aspirin-induced upper gastrointestinal bleeding in patients with peptic ulcer disease. Aspirin should not be administered to patients with a history of aspirin allergy characterized by bronchospasm. This problem occurs in ~0.3% of the general population but is more common in those with chronic urticaria or asthma, particularly in individuals with nasal pol­ yps or chronic rhinitis. Hepatic and renal toxicity are observed with aspirin overdose. Aspirin Resistance  Clinical aspirin resistance is defined as the failure of aspirin to protect patients from ischemic vascular events. This is not a helpful definition because it is made after the event occurs. Fur­ thermore, it is not realistic to expect aspirin, which only blocks throm­ boxane A2–induced platelet activation, to prevent all vascular events. Aspirin resistance has also been described biochemically as a fail­ ure of the drug to produce its expected inhibitory effects on tests of platelet function, such as thromboxane A2 synthesis or arachidonic acid–induced platelet aggregation. Potential causes of aspirin resistance include poor compliance, reduced absorption, drug-drug interaction with ibuprofen, and overexpression of COX-2. Unfortunately, the tests for aspirin resistance have not been well standardized, and there is little evidence that they identify patients at increased risk of recurrent vascu­ lar events, or that resistance can be reversed by giving higher doses of aspirin or by adding other antiplatelet drugs. Until such information is available, testing for aspirin resistance remains a research tool. CHAPTER 123 ■ ■ADP RECEPTOR ANTAGONISTS The ADP receptor antagonists include the thienopyridines (clopidogrel and prasugrel) as well as ticagrelor and cangrelor. All these drugs target P2Y12, the key ADP receptor on platelets. Antiplatelet, Anticoagulant, and Fibrinolytic Drugs Thienopyridines  •  MECHANISM OF ACTION  The thienopyridines are structurally related drugs that selectively inhibit ADP-induced platelet aggregation by irreversibly blocking P2Y12 (Fig. 123-3). Clopi­ dogrel and prasugrel are prodrugs that require metabolic activation by the hepatic cytochrome P450 (CYP) enzyme system. Prasugrel is about 10-fold more potent than clopidogrel and has a more rapid onset of action because of better absorption and more streamlined metabolic activation. INDICATIONS  When compared with aspirin in patients with recent ischemic stroke, recent MI, or a history of peripheral arterial disease, clopidogrel reduced the risk of cardiovascular death, MI, and stroke by 8.7%. Therefore, clopidogrel is more effective than aspirin but is also more expensive. Clopidogrel and aspirin are often combined to capi­ talize on their capacity to block complementary pathways of platelet activation. For example, the combination of aspirin plus clopidogrel is recommended for at least 4 weeks after implantation of a bare metal stent in a coronary artery and at least a year in those with a drug-eluting stent. Concerns about late in-stent thrombosis with drug-eluting stents have led some experts to recommend long-term use of clopidogrel plus aspirin for the latter indication. The course of dual-antiplatelet therapy is often shortened in patients at high risk of bleeding with the dropping of aspirin and continuation of the P2Y12 inhibitor. The combination of clopidogrel and aspirin is effective in patients with non-ST-segment elevation MI. Thus, in 12,562 such patients, the risk of cardiovascular death, MI, or stroke was 9.3% in those random­ ized to the combination of clopidogrel and aspirin and 11.4% in those given aspirin alone. This 20% relative risk reduction with combination therapy was highly statistically significant. However, combining clopi­ dogrel with aspirin increases the risk of major bleeding to about 2% per year. This bleeding risk persists even if the daily dose of aspirin is ≤100 mg. Therefore, the combination of clopidogrel and aspirin should only be used when there is a clear benefit. For example, this combina­ tion was not proven to be superior to clopidogrel alone in patients with acute ischemic stroke or to aspirin alone for primary prevention in those at risk for cardiovascular events. Prasugrel was compared with clopidogrel in 13,608 patients with acute coronary syndrome who were scheduled to undergo percutaneous coronary intervention. The incidence of the primary efficacy endpoint, a composite of cardiovascular death, MI, or stroke, was significantly lower with prasugrel than with clopidogrel (9.9% and 12.1%, respectively), mainly reflecting a reduction in nonfatal MI. The incidence of stent thrombosis also was significantly lower with prasugrel than with clopidogrel (1.1% and 2.4%, respectively). However, these advantages were at the expense of significantly higher rates of fatal bleeding (0.4% and 0.1%, respectively) and life-threatening bleeding (1.4% and 0.9%, respectively) with prasugrel. Because patients older than 75 years of age and those with a history of prior stroke or transient ischemic attack are at high risk of bleeding, prasugrel should generally be avoided in older patients, and the drug is contraindicated in those with a history of cere­ brovascular disease. Caution is required if prasugrel is used in patients weighing <60 kg or in those with renal impairment. When prasugrel was compared with clopidogrel in 7243 patients with unstable angina or MI without ST-segment elevation, prasugrel failed to reduce the rate of the primary efficacy endpoint, which was a composite of cardiovascular death, MI, and stroke. Because of the neg­ ative results of this study, prasugrel is reserved for patients undergoing percutaneous coronary intervention. In this setting, prasugrel is usually given in conjunction with aspirin. To reduce the risk of bleeding, the daily aspirin dose should be ≤100 mg. For patients with noncardioembolic stroke or high-risk transient ischemic attack, the combination of clopidogrel or ticagrelor plus aspi­ rin for 21–30 days followed by aspirin alone thereafter reduces the risk of stroke, MI, and vascular death by up to 30% compared with aspirin alone. Therefore, dual antiplatelet therapy is often administered for the first 3–4 weeks in such patients. PART 4 Oncology and Hematology DOSING  Clopidogrel is given once daily at a dose of 75 mg. Loading doses of clopidogrel are given when rapid ADP receptor blockade is desired. For example, patients undergoing coronary stenting are often given a loading dose of 300–600 mg, which produces inhibition of ADP-induced platelet aggregation in about 4–6 h. After a loading dose of 60 mg, prasugrel is given once daily at a dose of 10 mg. Patients older than age 75 years or weighing <60 kg should receive a lower daily prasugrel dose of 5 mg. SIDE EFFECTS  The most common side effect of clopidogrel and prasugrel is bleeding. Because of its greater potency, bleeding is more common with prasugrel than with clopidogrel. To reduce the risk of bleeding, clopidogrel and prasugrel should be stopped 5–7 days before major surgery. In patients taking clopidogrel or prasugrel who present with serious bleeding, platelet transfusion may be helpful. Hematologic side effects, including neutropenia, thrombocytopenia, and thrombotic thrombocytopenic purpura, are rare. THIENOPYRIDINE RESISTANCE  The capacity of clopidogrel to inhibit ADP-induced platelet aggregation varies among subjects. This vari­ ability reflects, at least in part, genetic polymorphisms in the CYP iso­ enzymes involved in the metabolic activation of clopidogrel. The most important of these is CYP2C19. Clopidogrel-treated patients who are homozygous for the loss-of-function CYP2C192 allele exhibit reduced platelet inhibition compared with those with the wild-type CYP2C19 allele and experience a higher rate of cardiovascular events. This is important because estimates suggest that up to 25% of whites, 30% of African Americans, and 50% of Asians carry the loss-of-function allele, which would render them resistant to clopidogrel. Even patients with the reduced-function CYP2C19 alleles may derive less benefit from clopidogrel than those with the full-function CYP2C19 allele. Con­ comitant administration of clopidogrel with proton pump inhibitors, which are inhibitors of CYP2C19, produces a small reduction in the inhibitory effects of clopidogrel on ADP-induced platelet aggregation. The extent to which this interaction increases the risk of cardiovascular events remains controversial. In contrast to their effect on the metabolic activation of clopidogrel, CYP2C19 polymorphisms appear to be less important determinants of the activation of prasugrel. Thus, no association was detected between the loss-of-function allele and decreased platelet inhibition or increased rate of cardiovascular events with prasugrel. The observation that genetic polymorphisms affecting clopidogrel absorption or metab­ olism influence clinical outcomes raised the possibility that pharmaco­ genetic profiling might be useful for identifying clopidogrel-resistant patients and that point-of-care assessment of the extent of clopidogrelinduced platelet inhibition may help detect patients at higher risk for subsequent cardiovascular events. Clinical trials designed to evaluate these possibilities have thus far been negative. Although administra­ tion of higher doses of clopidogrel can overcome a reduced response to clopidogrel, the clinical benefit of this approach is uncertain. Instead, prasugrel or ticagrelor may be better choices for these patients. Ticagrelor  As an orally active inhibitor of P2Y12, ticagrelor differs from the thienopyridines in that ticagrelor does not require metabolic activation and it produces reversible inhibition of the ADP receptor. MECHANISM OF ACTION  Like the thienopyridines, ticagrelor inhibits P2Y12. Because it does not require metabolic activation, ticagrelor has a more rapid onset and offset of action than clopidogrel, and it produces greater and more predictable inhibition of ADP-induced platelet aggre­ gation than clopidogrel. INDICATIONS  Ticagrelor is indicated for the secondary prevention of atherothrombotic events in patients with an acute coronary syndrome treated medically or with percutaneous coronary intervention (PCI) with or without stent implantation or with coronary artery bypass graft (CABG) surgery. Ticagrelor is also indicated for up to 3 years for sec­ ondary prevention in patients with a prior history of MI at least 1 year ago who are at high risk for atherothrombotic events. For patients with acute coronary syndrome undergoing PCI, guidelines give preference to ticagrelor over clopidogrel, particularly in higher risk patients. DOSING  Ticagrelor is initiated with an oral loading dose of 180 mg followed by 90 mg twice daily. The dose does not require adjustment in patients with renal impairment, but the drug should be used with caution in patients with hepatic disease and in those receiving potent inhibitors or inducers of CYP3A4 because ticagrelor is metabolized in the liver via CYP3A4. Ticagrelor is usually administered in conjunction with aspirin; the daily aspirin dose should not exceed 100 mg. SIDE EFFECTS  In addition to bleeding, the most common side effects of ticagrelor are dyspnea, which can occur in up to 15% of patients, and asymptomatic ventricular pauses. The dyspnea, which tends to occur soon after initiating ticagrelor, is usually self-limiting and mild in intensity. The mechanism responsible for this side effect is unknown. To reduce the risk of bleeding, ticagrelor should be stopped at least 5 days before major surgery. Platelet transfusion is unlikely to be of benefit in patients with ticagrelor-related bleeding or those requiring urgent surgery because the drug will bind to P2Y12 on the transfused platelets. Bentracimab, an antibody fragment that binds ticagrelor and its metabolite with high affinity and rapidly reverses their platelet inhibitory effects, is under development for ticagrelor reversal before urgent surgery or intervention or for patients with serious bleeding. Cangrelor  Cangrelor is a rapidly acting reversible inhibitor of P2Y12 that is administered intravenously. It has an immediate onset of action, a half-life of 3–5 min, and an offset of action within an hour. Cangrelor is licensed for use in patients undergoing PCI and produces rapid ADP receptor blockade in those who have not received pretreatment with clopidogrel, prasugrel, or ticagrelor. Cangrelor is administered as a 30 μg/kg IV bolus before PCI fol­ lowed by an infusion of 4 μg/kg per minute for at least 2 h or for the duration of the procedure, whichever is longer. When transitioning to oral P2Y12 inhibitor therapy, ticagrelor can be given at a loading dose of 180 mg at any time during the cangrelor infusion or immediately after discontinuation. In contrast, loading doses of prasugrel or clopidogrel (60 and 600 mg, respectively) should only be given after cangrelor is stopped because cangrelor blocks the interaction of their active metabolites with P2Y12. ■ ■DIPYRIDAMOLE Dipyridamole is a relatively weak antiplatelet agent on its own, but an extended-release formulation of dipyridamole combined with lowdose aspirin, a preparation known as Aggrenox, is sometimes used for secondary prevention in patients with transient ischemic attacks or ischemic stroke. MECHANISM OF ACTION  By inhibit­ ing phosphodiesterase, dipyridamole blocks the breakdown of cyclic adenos­ ine monophosphate (AMP). Increased levels of cyclic AMP reduce intracellular calcium and inhibit platelet activation. Dipyridamole also blocks the uptake of adenosine by platelets and other cells. This produces a further increase in local cyclic AMP levels because the platelet adenosine A2 receptor is coupled to adenylate cyclase (Fig. 123-4). Platelet INDICATIONS  Dipyridamole plus aspirin was compared with aspirin or dipyridamole alone, or with placebo, in patients with an ischemic stroke or transient ischemic attack. The combina­ tion reduced the risk of stroke by 22.1% compared with aspirin and by 24.4% compared with dipyridamole. A sec­ ond trial compared dipyridamole plus aspirin with aspirin alone for secondary prevention in patients with ischemic stroke. Vascular death, stroke, or MI occurred in 13% of patients given com­ bination therapy and in 16% of those treated with aspirin alone. Another trial randomized 20,332 patients with noncardioembolic ischemic stroke to either Aggrenox or clopi­ dogrel. The primary efficacy endpoint of recurrent stroke occurred in 9.0% of those given Aggrenox and in 8.8% of patients treated with clopidogrel. Although this difference was not statistically significant, the study failed to meet the prespecified margin to claim noninferior­ ity of Aggrenox relative to clopidogrel. These results have dampened enthusiasm for the use of Aggrenox. FIGURE 123-4  Mechanism of action of dipyridamole. Dipyridamole increases levels of cyclic AMP (cAMP) in platelets by (1) blocking the reuptake of adenosine and (2) inhibiting phosphodiesterase-mediated cyclic AMP degradation. By promoting calcium uptake, cyclic AMP reduces intracellular levels of calcium. This, in turn, inhibits platelet activation and aggregation. Because of its vasodilatory effects and the paucity of data supporting the use of dipyridamole in patients with symptomatic coronary artery disease, Aggrenox should not be used for stroke prevention in such patients. Clopidogrel is a better choice in this setting. DOSING  Aggrenox is given twice daily. Each capsule contains 200 mg of extended-release dipyridamole and 25 mg of aspirin. SIDE EFFECTS  Because dipyridamole has vasodilatory effects, it must be used with caution in patients with coronary artery disease. Gastroin­ testinal complaints, headache, facial flushing, dizziness, and hypoten­ sion can also occur. These symptoms often subside with continued use of the drug. ■ ■GP IIB/IIIA RECEPTOR ANTAGONISTS As a class, parenteral Gp IIb/IIIa receptor antagonists have a niche in patients with acute coronary syndrome. The three agents in this class are abciximab, eptifibatide, and tirofiban. However, abciximab is no longer available. Mechanism of Action  A member of the integrin family of adhe­ sion receptors, Gp IIb/IIIa is found on the surface of platelets and megakaryocytes. With about 80,000 copies per platelet, Gp IIb/IIIa is the most abundant receptor. Consisting of a noncovalently linked heterodimer, Gp IIb/IIIa is inactive on resting platelets. When platelets are activated, inside-outside signal transduction pathways trigger a conformational activation of the receptor. Once activated, Gp IIb/IIIa binds adhesive molecules, such as fibrinogen and, under high shear conditions, VWF. Binding is mediated by the Arg-Gly-Asp (RGD) sequence found on the α chains of fibrinogen and on VWF, and by the Lys-Gly-Asp (KGD) sequence located within a unique dodecapeptide domain on the γ chains of fibrinogen. Once bound, fibrinogen and/ or VWF bridge adjacent platelets together to induce platelet aggrega­ tion. Although abciximab, eptifibatide, and tirofiban all target the Gp IIb/IIIa receptor, they are structurally and pharmacologically distinct (Table 123-1). Abciximab is a Fab fragment of a humanized murine Reuptake Adenosine X Dipyridamole A2 Receptor Adenylate cyclase ATP Phosphodiesterase X AMP cAMP Ca2+ Activation and aggregation inhibited CHAPTER 123 monoclonal antibody directed against the activated form of Gp IIb/IIIa. Abciximab binds to the activated receptor with high affinity and blocks the binding of adhesive molecules. In contrast, eptifibatide and tirofiban are synthetic small molecules. Eptifibatide is a cyclic heptapeptide that binds Gp IIb/IIIa because it incorporates the KGD motif, whereas tiro­ fiban is a nonpeptidic tyrosine derivative that acts as an RGD mimetic. Abciximab has a long half-life and can be detected on the surface of platelets for up to 2 weeks; eptifibatide and tirofiban have short half-lives. Antiplatelet, Anticoagulant, and Fibrinolytic Drugs Indications  Abciximab and eptifibatide are used in patients under­ going PCIs, particularly those who have not been pretreated with an ADP receptor antagonist. Tirofiban and eptifibatide are used in highrisk patients with non-ST-segment elevation MI. Dosing  All the Gp IIb/IIIa antagonists are given as an IV bolus fol­ lowed by an infusion. The recommended dose of abciximab is a bolus of 0.25 mg/kg followed by an infusion of 0.125 μg/kg per minute to a maximum of 10 μg/kg for 12 h. In patients undergoing PCI, eptifiba­ tide is given as two 180 μg/kg boluses given 10 min apart, followed by an infusion of 2.0 μg/kg per minute for 18–24 h. For patients with acute coronary syndrome, the second eptifibatide bolus is withheld. Tirofi­ ban is started at a rate of 0.4 μg/kg per minute for 30 min; the drug is then continued at a rate of 0.1 μg/kg per minute for up to 18 h. Because eptifibatide and tirofiban are cleared by the kidneys, the doses must be reduced in patients with renal insufficiency. Thus, the eptifibatide infusion is reduced to 1 μg/kg per minute in patients with a creatinine clearance below 50 mL/min, whereas the dose of tirofiban is cut in half for patients with a creatinine clearance below 30 mL/min. TABLE 123-1  Features of Gp IIb/IIIa Antagonists FEATURE ABCIXIMAB EPTIFIBATIDE TIROFIBAN Description Fab fragment of humanized mouse monoclonal antibody Cyclical KGDcontaining heptapeptide Nonpeptidic RGD mimetic Specific for Gp IIb/IIIa No Yes Yes Plasma half-life Short (min) Long (2.5 h) Long (2.0 h) Platelet-bound half-life Long (days) Short (s) Short (s) Renal clearance No Yes Yes Abbreviation: Gp, glycoprotein. Side Effects  In addition to bleeding, thrombocytopenia is the most serious complication. Thrombocytopenia is immune-mediated and is caused by antibodies directed against neoantigens on Gp IIb/IIIa that are exposed upon antagonist binding. With abciximab, thrombocyto­ penia occurs in up to 5% of patients. Thrombocytopenia is severe in ~1% of these individuals. Thrombocytopenia is less common with the other two agents, occurring in ~1% of patients. ■ ■VORAPAXAR An orally active PAR-1 antagonist, vorapaxar blocks thrombin-induced platelet activation. Vorapaxar has a half-life of about 200 h. Indications  When compared with a placebo in 12,944 patients with acute coronary syndrome without ST-segment elevation, vorapaxar failed to significantly reduce the primary efficacy endpoint, a compos­ ite of cardiovascular death, MI, stroke, recurrent ischemia requiring rehospitalization, and urgent coronary revascularization. Moreover, vorapaxar was associated with increased rates of bleeding, including intracranial bleeding. In a second trial, vorapaxar was compared with placebo for secondary prevention in 26,449 patients with prior MI, ischemic stroke, or peripheral arterial disease. Overall, vorapaxar reduced the risk of cardiovascular death, MI, or stroke by 13%, but doubled the risk of intracranial bleeding. In the prespecified subgroup of 17,779 patients with prior MI, however, vorapaxar reduced the risk for cardiovascular death, MI, or stroke by 20% compared with placebo (from 9.7% to 8.1%, respectively). The rate of intracranial hemorrhage was higher with vorapaxar than with placebo (0.6% and 0.4%, respectively; p = .076) as was the rate of moderate or severe bleeding (3.4% and 2.1%, respectively; p <.0001). Based on these data, vorapaxar is licensed for patients younger than 75 years of age with MI or peripheral artery disease who have no history of stroke, transient ischemic attack, or intracranial bleeding and weigh >60 kg. PART 4 Oncology and Hematology Factor Xa A Unfractionated heparin Antithrombin Dosing  Vorapaxar is given at a dose of 2.08 mg once daily. Side Effects  The major side effect is bleeding. Platelet transfusion may be of ben­ efit for vorapaxar reversal. Low-molecularweight heparin B ANTICOAGULANTS There are both parenteral and oral anticoag­ ulants. The parenteral anticoagulants include heparin, low-molecular-weight heparin (LMWH), fondaparinux (a synthetic penta­ saccharide), lepirudin, desirudin, bivaliru­ din, and argatroban. Currently available oral anticoagulants include warfarin; dabigatran etexilate, an oral thrombin inhibitor; and rivaroxaban, apixaban, and edoxaban, which are oral factor Xa inhibitors. Pentasaccharide C ■ ■PARENTERAL ANTICOAGULANTS Heparin  A sulfated polysaccharide, heparin is isolated from mammalian tis­ sues rich in mast cells. Most commercial heparin is derived from porcine intestinal mucosa and is a polymer of alternating d-glucuronic acid and N-acetyl-d-glucos­ amine residues. FIGURE 123-5  Mechanism of action of heparin, low-molecular-weight heparin (LMWH), and fondaparinux, a synthetic pentasaccharide. A. Heparin binds to antithrombin via its pentasaccharide sequence. This induces a conformational change in the reactive center loop of antithrombin that accelerates its interaction with factor Xa. To potentiate thrombin inhibition, heparin must simultaneously bind to antithrombin and thrombin. Only heparin chains composed of at least 18 saccharide units, which corresponds to a molecular weight of 5400, are of sufficient length to perform this bridging function. With a mean molecular weight of 15,000, all the heparin chains are long enough to do this. B. LMWH has greater capacity to potentiate factor Xa inhibition by antithrombin than thrombin because, with a mean molecular weight of 4500–5000, at least half of the LMWH chains are too short to bridge antithrombin to thrombin. C. Fondaparinux, a synthetic pentasaccharide, only accelerates factor Xa inhibition by antithrombin because it is too short to bridge antithrombin to thrombin. MECHANISM OF ACTION  Heparin acts as an anticoagulant by activating antithrombin (previously known as antithrombin III) and accelerating the rate at which antithrombin inhibits clotting enzymes, particularly thrombin and factor Xa. Antithrombin, the obligatory plasma cofactor for hepa­ rin, is a member of the serine protease inhibitor (serpin) superfamily. Synthesized in the liver and circulating in plasma at a concentration of 2.6 ± 0.4 μM, antithrombin acts as a suicide substrate for its target enzymes. To activate antithrombin, heparin binds to the serpin via a unique pentasaccharide sequence that is found on one-third of the chains of commercial heparin (Fig. 123-5). Heparin chains without this pen­ tasaccharide sequence have little or no anticoagulant activity. Once bound to antithrombin, heparin induces a conformational change in the reactive center loop of antithrombin that renders it more readily accessible to its target proteases. This conformational change enhances the rate at which antithrombin inhibits factor Xa by at least two orders of magnitude but has little effect on the rate of thrombin inhibition. To catalyze thrombin inhibition, heparin serves as a template that binds antithrombin and thrombin simultaneously. Formation of this ternary complex brings the enzyme in close apposition to the inhibitor, thereby promoting the formation of a stable covalent thrombin-antithrombin complex. Only pentasaccharide-containing heparin chains composed of at least 18 saccharide units (which correspond to a molecular weight of 5400) are of sufficient length to bridge thrombin and antithrombin Pentasaccharide sequence Thrombin together. With a mean molecular weight of 15,000, and a range of 5000–30,000, almost all the chains of unfractionated heparin are long enough to do so. Consequently, by definition, heparin has equal capac­ ity to promote the inhibition of thrombin and factor Xa by antithrom­ bin and is assigned an anti–factor Xa to anti–factor IIa (thrombin) ratio of 1:1. Heparin causes the release of tissue factor pathway inhibitor (TFPI) from the endothelium. A factor Xa–dependent inhibitor of tissue factor– bound factor VIIa, TFPI may contribute to the antithrombotic activity of heparin. Longer heparin chains induce the release of more TFPI than shorter ones. PHARMACOLOGY  Heparin must be given parenterally. It is usu­ ally administered SC or by continuous IV infusion. When used for therapeutic purposes, the IV route is most often employed. If heparin is given SC for treatment of thrombosis, the dose of heparin must be high enough to overcome the limited bioavailability associated with this method of delivery. In the circulation, heparin binds to the endothelium and to plasma proteins other than antithrombin. Heparin binding to endothelial cells explains its dose-dependent clearance. At low doses, the halflife of heparin is short because it binds rapidly to the endothelium. With higher doses of heparin, the half-life is longer because heparin is cleared more slowly once the endothelium is saturated. Clearance is mainly extrarenal; heparin binds to macrophages, which internalize and depolymerize the long heparin chains and secrete shorter chains back into the circulation. Because of its dose-dependent clearance mechanism, the plasma half-life of heparin ranges from 30 to 60 min with bolus IV doses of 25 and 100 units/kg, respectively. Once heparin enters the circulation, it binds to plasma proteins other than antithrombin, a phenomenon that reduces its anticoagulant activity. Some of the heparin-binding proteins found in plasma are acute-phase reactants whose levels are elevated in ill patients. Others, such as high-molecular-weight multimers of VWF, are released from activated platelets or endothelial cells. Activated platelets also release platelet factor 4 (PF4), a highly cationic protein that binds heparin with high affinity. The large amounts of PF4 found in the vicinity of platelet-rich arterial thrombi can neutralize the anticoagulant activity of heparin. This phenomenon may attenuate heparin’s capacity to sup­ press thrombus growth. Because the levels of heparin-binding proteins in plasma vary from person to person, the anticoagulant response to fixed or weightadjusted doses of heparin is unpredictable. Consequently, coagula­ tion monitoring is essential to ensure that a therapeutic response is obtained. This is particularly important when heparin is administered for treatment of established thrombosis because a subtherapeutic anti­ coagulant response may render patients at risk for recurrent thrombo­ sis, whereas excessive anticoagulation increases the risk of bleeding. MONITORING THE ANTICOAGULANT EFFECT  Heparin therapy can be monitored using the activated partial thromboplastin time (aPTT) or anti–factor Xa level. Although the aPTT is the test most often used for this purpose, there are problems with this assay. aPTT reagents vary in their sensitivity to heparin, and the type of coagulometer used for testing can influence the results. Consequently, laboratories must establish a therapeutic aPTT range with each reagent-coagulometer combination by measuring the aPTT and anti–factor Xa level in plasma samples collected from heparin-treated patients. For most of the aPTT reagents and coagulometers in current use, therapeutic heparin levels are achieved with a two- to threefold prolongation of the aPTT. Anti– factor Xa levels also can be used to monitor heparin therapy. With this test, therapeutic heparin levels range from 0.3 to 0.7 units/mL. Up to 25% of heparin-treated patients with VTE require >35,000 units/d to achieve a therapeutic aPTT. These patients are considered heparin resistant. It is useful to measure anti–factor Xa lev­ els in heparin-resistant patients because many will have a therapeutic anti–factor Xa level despite a subtherapeutic aPTT. This dissociation in test results occurs because elevated plasma levels of fibrinogen and factor VIII, both of which are acute-phase proteins, shorten the aPTT but have no effect on anti–factor Xa levels. Heparin therapy in patients who exhibit this phenomenon is best monitored using anti–factor Xa levels instead of the aPTT. Patients with congenital or acquired anti­ thrombin deficiency and those with elevated levels of heparin-binding proteins may also need high doses of heparin to achieve a therapeutic aPTT or anti–factor Xa level. If there is good correlation between the aPTT and the anti–factor Xa level, either test can be used to monitor heparin therapy. DOSING  For prophylaxis, heparin is usually given in fixed doses of 5000 units SC two or three times daily. With these low doses, coagula­ tion monitoring is unnecessary. In contrast, monitoring is essential when the drug is given in therapeutic doses. Fixed-dose or weightbased heparin nomograms are used to standardize heparin dosing and to shorten the time required to achieve a therapeutic anticoagulant response. At least two heparin nomograms have been validated in patients with VTE and reduce the time required to achieve a thera­ peutic aPTT. Weight-adjusted heparin nomograms have also been evaluated in patients with acute coronary syndromes. After an IV heparin bolus of 5000 units or 70 units/kg, a heparin infusion rate of 12–15 units/kg per hour is usually administered. In contrast, weightadjusted heparin nomograms for patients with VTE use an initial bolus of 5000 units or 80 units/kg, followed by an infusion of 18 units/ kg per hour. Thus, patients with VTE appear to require higher doses of heparin to achieve a therapeutic aPTT than do patients with acute coronary syndromes. This may reflect differences in the thrombus bur­ den. Heparin binds to fibrin, and the amount of fibrin in patients with extensive DVT is greater than that in those with coronary thrombosis. CHAPTER 123 LIMITATIONS  Heparin has pharmacokinetic and biophysical limitations (Table 123-2). The pharmacokinetic limitations reflect heparin’s propen­ sity to bind in a pentasaccharide-independent fashion to cells and plasma proteins. Heparin binding to endothelial cells explains its dose-dependent clearance, whereas binding to plasma proteins results in a variable antico­ agulant response and can lead to heparin resistance. Antiplatelet, Anticoagulant, and Fibrinolytic Drugs The biophysical limitations of heparin reflect the inability of the heparin-antithrombin complex to inhibit factor Xa when it is incor­ porated into the prothrombinase complex, the complex that converts prothrombin to thrombin, and to inhibit thrombin bound to fibrin. Consequently, factor Xa bound to activated platelets within plateletrich thrombi has the potential to generate thrombin, even in the face of heparin. Once this thrombin binds to fibrin, it too is protected from inhibition by the heparin-antithrombin complex. Clot-associated thrombin can then trigger thrombus growth by locally activating platelets and amplifying its own generation through feedback activa­ tion of factors V, VIII, and XI. Further compounding the problem is the potential for heparin neutralization by the high concentrations of PF4 released from activated platelets within the platelet-rich thrombus. SIDE EFFECTS  The most common side effect of heparin is bleeding. Other complications include thrombocytopenia, osteoporosis, and elevated levels of transaminases. Bleeding  The risk of bleeding rises as the dose of heparin is increased. Concomitant administration of drugs that affect hemostasis, such as antiplatelet or fibrinolytic agents, increases the risk of bleeding, as does TABLE 123-2  Pharmacokinetic and Biophysical Limitations of Heparin LIMITATIONS MECHANISM Poor bioavailability at low doses Binds to endothelial cells and macrophages Dose-dependent clearance Binds to macrophages Variable anticoagulant response Binds to plasma proteins whose levels vary from patient to patient Reduced activity in the vicinity of platelet-rich thrombi Neutralized by platelet factor 4 released from activated platelets Limited activity against factor Xa incorporated in the prothrombinase complex and thrombin bound to fibrin Reduced capacity of heparinantithrombin complex to inhibit factor Xa bound to activated platelets and thrombin bound to fibrin TABLE 123-3  Features of Heparin-Induced Thrombocytopenia FEATURES DETAILS Thrombocytopenia Platelet count of ≤100,000/μL or a decrease in platelet count of ≥50% Timing Platelet count falls 5–14 days after starting heparin Type of heparin More common with unfractionated heparin than lowmolecular-weight heparin Type of patient More common in surgical patients and patients with cancer than general medical patients; more common in women than in men Thrombosis Venous thrombosis more common than arterial thrombosis recent surgery or trauma. Heparin-treated patients with serious bleed­ ing can be given protamine sulfate to neutralize the heparin. Protamine sulfate, a mixture of basic polypeptides isolated from salmon sperm, binds heparin with high affinity, and the resultant protamine-heparin complexes are then cleared. Typically, 1 mg of protamine sulfate neu­ tralizes 100 units of heparin. Protamine sulfate is given IV at a maxi­ mum amount of 50 mg per dose. Anaphylactoid reactions to protamine sulfate can occur, and drug administration by slow IV infusion is rec­ ommended to reduce the risk. Thrombocytopenia  Heparin can cause thrombocytopenia. Heparininduced thrombocytopenia (HIT) is an antibody-mediated process that is triggered by antibodies directed against neoantigens on PF4 that are exposed when heparin binds to this protein. These antibod­ ies, which are usually of the IgG isotype, bind simultaneously to the heparin-PF4 complex and to platelet Fc receptors. Such binding acti­ vates the platelets and generates platelet microparticles. Circulating microparticles are procoagulant because they express anionic phos­ pholipids on their surface and can bind clotting factors and promote thrombin generation. The clinical features of HIT are illustrated in Table 123-3. Typically, HIT occurs 5–14 days after initiation of heparin therapy, but it can manifest earlier if the patient has received heparin within the past 3 months. A platelet count <100,000/μL or a 50% decrease in the platelet count from the pretreatment value should raise the suspicion of HIT. HIT is more common in surgical patients than in medical patients and, like many autoimmune disorders, occurs more frequently in females than in males. PART 4 Oncology and Hematology HIT can be associated with thrombosis, either arterial or venous. Venous thrombosis, which manifests as DVT and/or PE, is more com­ mon than arterial thrombosis. Arterial thrombosis can manifest as ischemic stroke or acute MI. Rarely, platelet-rich thrombi in the distal aorta or iliac arteries can cause critical limb ischemia. The diagnosis of HIT is established using enzyme-linked assays to detect antibodies against heparin-PF4 complexes or with platelet activation assays. Enzyme-linked assays are sensitive but can be posi­ tive in the absence of any clinical evidence of HIT. The most specific diagnostic test for HIT is the serotonin release assay. This test is per­ formed by quantifying serotonin release when washed platelets loaded with labeled serotonin are exposed to patient serum in the absence or presence of varying concentrations of heparin. If the patient serum contains the HIT antibody, heparin addition induces platelet activa­ tion and serotonin release. Management of HIT is outlined in Table 123-4. Heparin should be stopped in patients with suspected or docu­ mented HIT, and an alternative anticoagulant should be administered TABLE 123-4  Management of Heparin-Induced Thrombocytopenia Stop all heparins. Give an alternative anticoagulant, such as argatroban, bivalirudin, fondaparinux, or rivaroxaban. Do not give platelet transfusions. Do not give warfarin until the platelet count returns to its baseline level. If warfarin was administered, give vitamin K to restore the INR to normal. Evaluate for thrombosis, particularly deep vein thrombosis. Abbreviation: INR, international normalized ratio. to prevent or treat thrombosis. The agents most often used for this indication are parenteral direct thrombin inhibitors, such as argatroban or bivalirudin, or factor Xa inhibitors, such as fondaparinux or rivar­ oxaban. A HIT-like syndrome known as vaccine-induced thrombotic thrombocytopenia was reported as a rare complication after vaccina­ tion with adenovirus COVID-19 vaccines. Characterized by thrombo­ sis and thrombocytopenia that occurred 4–28 days after vaccination, patients presented with cerebral or splanchnic vein thrombosis as well as DVT or PE. The diagnosis is established by the detection of antibod­ ies against PF4 and a positive serotonin release assay with added PF4. Treatment can include intravenous immunoglobulin, steroids, and plasma exchange to offset the effects of the antibodies against PF4, as well as anticoagulants such as argatroban, fondaparinux, or rivaroxa­ ban to treat the thrombosis. Patients with HIT, particularly those with associated thrombosis, often have evidence of increased thrombin generation that can lead to consumption of protein C. If these patients are given warfarin without a concomitant anticoagulant that inhibits thrombin or thrombin genera­ tion, the further decrease in protein C levels induced by the warfarin can trigger skin necrosis. To avoid this problem, patients with HIT should be treated with a direct thrombin inhibitor or with fondaparinux until the platelet count returns to normal levels. At this point, low-dose warfarin therapy can be introduced, and the parenteral anticoagulant can be discontinued when the international normalized ratio (INR) has been therapeutic for at least 2 days. Alternatively, a direct oral antico­ agulant, such as apixaban or rivaroxaban, can be given. Osteoporosis  Treatment with therapeutic doses of heparin for >1 month can cause a reduction in bone density. This complication has been reported in up to 30% of patients given long-term heparin therapy, and symptomatic vertebral fractures occur in 2–3% of these individuals. Heparin affects the activity of osteoblasts and osteoclasts and causes bone loss both by decreasing bone formation and by enhancing bone resorption. Elevated Levels of Transaminases  Therapeutic doses of heparin are fre­ quently associated with modest elevations in the serum levels of hepatic transaminases without a concomitant increase in the level of bilirubin. The levels of transaminases rapidly return to normal when heparin is stopped. The mechanism responsible for this phenomenon is unknown. Low-Molecular-Weight Heparin  Consisting of smaller frag­ ments of heparin, LMWH is prepared from unfractionated heparin by controlled enzymatic or chemical depolymerization. The mean molec­ ular weight of LMWH is about 5000, one-third the mean molecular weight of unfractionated heparin. LMWH has advantages over heparin (Table 123-5) and has replaced heparin for most indications. MECHANISM OF ACTION  Like heparin, LMWH exerts its anticoagu­ lant activity by activating antithrombin. With a mean molecular weight of 5000, which corresponds to about 17 saccharide units, at least half of the pentasaccharide-containing chains of LMWH are too short to bridge thrombin to antithrombin (Fig. 123-5). However, these chains retain the capacity to accelerate factor Xa inhibition by antithrombin TABLE 123-5  Advantages of LMWH Over Heparin ADVANTAGE CONSEQUENCE Better bioavailability and longer halflife after subcutaneous injection Can be given subcutaneously once or twice daily for both prophylaxis and treatment Dose-independent clearance Simplified dosing Predictable anticoagulant response Coagulation monitoring is unnecessary in most patients Lower risk of heparin-induced thrombocytopenia Safer than heparin for short- or longterm administration Lower risk of osteoporosis Safer than heparin for extended administration Abbreviation: LMWH, low-molecular-weight heparin. because this activity is largely the result of the conformational changes in antithrombin evoked by pentasaccharide binding. Consequently, LMWH catalyzes factor Xa inhibition by antithrombin more than thrombin inhibition. Depending on their unique molecular weight distributions, LMWH preparations have anti–factor Xa to anti–factor IIa ratios ranging from 2:1 to 4:1. PHARMACOLOGY  Although usually given SC, LMWH also can be administered IV if a rapid anticoagulant response is needed. LMWH has pharmacokinetic advantages over heparin. These advantages reflect the fact that shorter heparin chains bind less avidly to endothe­ lial cells, macrophages, and heparin-binding plasma proteins. Reduced binding to endothelial cells and macrophages eliminates the rapid, dose-dependent, and saturable mechanism of clearance that is a char­ acteristic of unfractionated heparin. Instead, the clearance of LMWH is dose-independent and its plasma half-life is longer. Based on measure­ ment of anti–factor Xa levels, LMWH has a plasma half-life of ~4–6 h. LMWH is cleared almost exclusively by the kidneys, and the drug can accumulate in patients with renal insufficiency. LMWH exhibits about 90% bioavailability after SC injection. Because LMWH binds less avidly to heparin-binding proteins in plasma than heparin, LMWH produces a more predictable dose response, and resistance to LMWH is rare. With a longer half-life and more predictable anticoagulant response, LMWH can be given SC once or twice daily without coagulation monitoring, even when the drug is given in treatment doses. These properties render LMWH more convenient to administer than unfractionated heparin. Capitalizing on this feature, studies in patients with VTE have shown that home treatment with LMWH is as effective and safe as in-hospital treat­ ment with continuous IV infusions of heparin. Outpatient treatment with LMWH streamlines care, reduces health care costs, and increases patient satisfaction. MONITORING  In most patients, LMWH does not require coagulation monitoring. If monitoring is necessary, anti–factor Xa levels must be measured because LMWH preparations have little effect on the aPTT. Therapeutic anti–factor Xa levels for once-daily and twice-daily dos­ ing of LMWH range from 0.5 to 1.2 units/mL and 1.0 to 2.0 units/mL, respectively, when measured 3–4 h after drug administration. When LMWH is given in prophylactic doses, peak anti–factor Xa levels of 0.2–0.5 units/mL are desirable. Indications for LMWH monitoring include renal impairment and obesity. LMWH monitoring in patients with a creatinine clearance ≤30 mL/min is advisable to ensure that there is no drug accumula­ tion. Although weight-adjusted LMWH dosing appears to produce therapeutic anti–factor Xa levels in patients who are overweight, this approach has not been extensively evaluated in those with morbid obe­ sity. It may also be advisable to monitor the anticoagulant activity of LMWH during pregnancy because dose requirements can change, par­ ticularly in the third trimester. Monitoring should also be considered in high-risk settings, such as in pregnant women with mechanical heart valves who are given LMWH to prevent valve thrombosis, and when LMWH is used in treatment doses in infants or children. DOSING  The doses of LMWH recommended for prophylaxis or treat­ ment vary depending on the LMWH preparation. For prophylaxis, once-daily SC doses of 4000–5000 units are often used, whereas doses of 2500–3000 units are given when the drug is administered twice daily. For treatment of VTE, a dose of 150–200 units/kg is given if the drug is administered once daily. If a twice-daily regimen is used, a dose of 100 units/kg is given. In patients with unstable angina, LMWH is given SC on a twice-daily basis at a dose of 100–120 units/kg. SIDE EFFECTS  The major complication of LMWH is bleeding. Metaanalyses suggest that the risk of major bleeding is lower with LMWH than with unfractionated heparin. HIT and osteoporosis are less com­ mon with LMWH than with unfractionated heparin. Bleeding  Like the situation with heparin, bleeding with LMWH is more common in patients receiving concomitant therapy with anti­ platelet or fibrinolytic drugs. Recent surgery, trauma, or underlying hemostatic defects also increase the risk of bleeding with LMWH. Although protamine sulfate can be used as an antidote for LMWH, protamine sulfate incompletely neutralizes the anticoagulant activity of LMWH because it only binds the longer chains of LMWH. Because longer chains are responsible for catalysis of thrombin inhibition by antithrombin, protamine sulfate completely reverses the anti–factor IIa activity of LMWH. In contrast, protamine sulfate only partially reverses the anti–factor Xa activity of LMWH because the shorter pen­ tasaccharide-containing chains of LMWH do not bind to protamine sulfate. Consequently, patients at high risk for bleeding may be more safely treated with continuous IV unfractionated heparin than with SC LMWH. Andexanet alfa, a recombinant factor Xa variant licensed for reversal of oral factor Xa inhibitors, reverses that anti–factor Xa activity of LMWH but not its anti–factor IIa activity. The utility of andexanet for LMWH reversal is uncertain, and it is not licensed for this indication. Thrombocytopenia  The risk of HIT is about fivefold lower with LMWH than with heparin. LMWH binds less avidly to platelets and causes less PF4 release. Furthermore, with lower affinity for PF4 than heparin, LMWH is less likely to induce the conformational changes in PF4 that trigger the formation of HIT antibodies. LMWH should not be used to treat HIT patients because most HIT antibodies exhibit cross-reactivity with LMWH. This in vitro cross-reactivity is more than a laboratory phenomenon because there are case reports of thrombosis when HIT patients were switched from heparin to LMWH. CHAPTER 123 Osteoporosis  Because the risk of osteoporosis is lower with LMWH than with heparin, LMWH is a better choice than heparin for extended treatment. Antiplatelet, Anticoagulant, and Fibrinolytic Drugs Fondaparinux  A synthetic analogue of the antithrombin-binding pentasaccharide sequence, fondaparinux differs from LMWH in sev­ eral ways (Table 123-6). Fondaparinux is licensed for thromboprophy­ laxis in general medical or surgical patients and in high-risk orthopedic patients and as an alternative to heparin or LMWH for initial treatment of patients with established VTE. Although fondaparinux is used in Europe as an alternative to heparin or LMWH in patients with acute coronary syndrome, the drug is not licensed for this indication in the United States. MECHANISM OF ACTION  Fondaparinux has a molecular weight of 1728. Fondaparinux binds only to antithrombin (Fig. 123-5) and is too short to bridge thrombin to antithrombin. Consequently, fondaparinux catalyzes factor Xa inhibition by antithrombin and does not enhance the rate of thrombin inhibition. PHARMACOLOGY  Fondaparinux exhibits complete bioavailability after SC injection. With no binding to endothelial cells or plasma proteins, the clearance of fondaparinux is dose independent, and its plasma half-life is 17 h. The drug is given SC once daily. Because fondaparinux is cleared unchanged via the kidneys, it is contraindi­ cated in patients with a creatinine clearance <30 mL/min and should be used with caution in those with a creatinine clearance <50 mL/min. DOSING  Fondaparinux produces a predictable anticoagulant response after administration in fixed doses because it does not bind to plasma proteins. The drug is given at a dose of 2.5 mg once daily for preven­ tion of VTE. For initial treatment of established VTE, fondaparinux is TABLE 123-6  Comparison of LMWH and Fondaparinux FEATURES LMWH FONDAPARINUX Number of saccharide units 15–17 Catalysis of factor Xa inhibition Yes Yes Catalysis of thrombin inhibition Yes No Bioavailability after subcutaneous administration (%) Plasma half-life (h) Renal excretion Yes Yes Induces release of tissue factor pathway inhibitor Yes No Neutralized by protamine sulfate Partially No given at a dose of 7.5 mg once daily. The dose can be reduced to 5 mg once daily for those weighing <50 kg and increased to 10 mg for those >100 kg. When given in these doses, fondaparinux is as effective as heparin or LMWH for initial treatment of patients with DVT or PE and is associated with similar rates of bleeding. Fondaparinux is used at a dose of 2.5 mg once daily in patients with acute coronary syndrome. When this prophylactic dose of fondaparinux was compared with treatment doses of enoxaparin in patients with non-ST-segment elevation MI, there was no difference in the rate of cardiovascular death, MI, or stroke at 9 days. However, the rate of major bleeding was 50% lower with fondaparinux than with enoxaparin, a difference that likely reflects the fact that the dose of fondaparinux was lower than that of enoxaparin. In acute coronary syndrome patients who require PCI, there is a risk of catheter throm­ bosis with fondaparinux unless adjunctive heparin is given at the time of the procedure. SIDE EFFECTS  Fondaparinux does not cause HIT because it does not bind to PF4. In contrast to LMWH, there is no cross-reactivity of fondaparinux with HIT antibodies. Consequently, fondaparinux appears to be effective for treatment of HIT patients, although large clinical trials supporting its use are lacking. The major side effect of fondaparinux is bleeding. Fondaparinux has no antidote. Protamine sulfate has no effect on the anticoagulant activity of fondaparinux because it fails to bind to the drug. Andexanet alfa has been reported to reverse fondaparinux in vitro, but studies in patients are lacking. Recombinant activated factor VII reverses the anticoagulant effects of fondaparinux in volunteers, but it is unknown whether this agent controls fondaparinux-induced bleeding. PART 4 Oncology and Hematology Parenteral Direct Thrombin Inhibitors  Direct thrombin inhibi­ tors bind directly to thrombin and block its interaction with its substrates. Approved parenteral direct thrombin inhibitors include recombinant hirudins (lepirudin and desirudin), argatroban, and bivalirudin (Table 123-7). Lepirudin and desirudin are no longer available. ARGATROBAN  A univalent inhibitor that targets the active site of thrombin, argatroban is metabolized in the liver. Consequently, this drug must be used with caution in patients with hepatic insufficiency. Argatroban is administered by continuous IV infusion and has a plasma half-life of ~45 min. The aPTT is used to monitor its anticoagu­ lant effect, and the dose is adjusted to achieve an aPTT 1.5–3 times the baseline value, but not to exceed 100 s. Argatroban also prolongs the INR, a feature that can complicate the transitioning of patients from argatroban to warfarin. This problem can be circumvented by using the levels of factor X to monitor warfarin instead of the INR. Alternatively, argatroban can be stopped for 2–3 h before INR determination. Argatroban is licensed for treatment of patients with HIT or a his­ tory of HIT, including those requiring PCI. In such patients, argatroban is most useful for those with severe kidney disease because unlike fondaparinux and bivalirudin, it is not cleared through the kidneys. BIVALIRUDIN  A synthetic 20-amino-acid analogue of hirudin, bivali­ rudin is a divalent thrombin inhibitor. Thus, the N-terminus of bivali­ rudin interacts with the active site of thrombin, whereas its C-terminus binds to exosite 1. Bivalirudin has a plasma half-life of 25 min, the shortest half-life of all the parenteral direct thrombin inhibitors. Bivalirudin is degraded by peptidases and is partially excreted via the TABLE 123-7  Comparison of the Properties of Desirudin, Bivalirudin, and Argatroban   DESIRUDIN BIVALIRUDIN ARGATROBAN Molecular mass Site(s) of interaction with thrombin Active site and exosite 1 Active site and exosite 1 Active site Renal clearance Yes No No Hepatic metabolism No No Yes Plasma half-life (min) 60 (IV) 120–180 (SC) kidneys. When given in high doses in the cardiac catheterization labo­ ratory, the anticoagulant activity of bivalirudin is monitored using the activated clotting time. With lower doses, its activity can be assessed using the aPTT. Bivalirudin is licensed as an alternative to heparin in patients under­ going PCI. Bivalirudin also has been used successfully in HIT patients who require PCI or cardiac bypass surgery. ■ ■ORAL ANTICOAGULANTS For many years, vitamin K antagonists such as warfarin were the only available oral anticoagulants. This situation changed with the intro­ duction of the direct oral anticoagulants, which include dabigatran, rivaroxaban, apixaban, and edoxaban. Warfarin  A water-soluble vitamin K antagonist initially developed as a rodenticide; warfarin is the coumarin derivative most often pre­ scribed in North America. Like other vitamin K antagonists, warfarin interferes with the synthesis of the vitamin K–dependent clotting pro­ teins, which include prothrombin (factor II) and factors VII, IX, and X. The synthesis of the vitamin K–dependent anticoagulant proteins, proteins C and S, is also reduced by vitamin K antagonists. MECHANISM OF ACTION  All of the vitamin K–dependent clotting factors possess glutamic acid residues at their N termini. A posttransla­ tional modification adds a carboxyl group to the γ-carbon of these resi­ dues to generate γ-carboxyglutamic acid. This modification is essential for expression of the activity of these clotting factors because it permits their calcium-dependent binding to negatively charged phospholipid surfaces. The γ-carboxylation process is catalyzed by a vitamin K– dependent carboxylase. Thus, vitamin K from the diet is reduced to vitamin K hydroquinone by vitamin K reductase (Fig. 123-6). Vita­ min K hydroquinone serves as a cofactor for the carboxylase enzyme, which in the presence of carbon dioxide replaces the hydrogen on the γ-carbon of glutamic acid residues with a carboxyl group. During this process, vitamin K hydroquinone is oxidized to vitamin K epoxide, which is then reduced to vitamin K by vitamin K epoxide reductase. Nonfunctional Prozymogens Functional Zymogens γ-glutamyl carboxylase O2 CO2 Reduced vitamin K Vitamin K cycle Oxidized vitamin K Vitamin K reductase x CYP1A1 CYP1A2 CYP3A4 CYP2C9 R-warfarin S-warfarin Warfarin metabolism Warfarin FIGURE 123-6  Mechanism of action of warfarin. A racemic mixture of S- and R-enantiomers, S-warfarin is most active. By blocking vitamin K epoxide reductase, warfarin inhibits the conversion of oxidized vitamin K into its reduced form. This inhibits vitamin K–dependent γ-carboxylation of factors II, VII, IX, and X because reduced vitamin K serves as a cofactor for a γ-glutamyl carboxylase that catalyzes the γ-carboxylation process, thereby converting pro-zymogens to zymogens capable of binding calcium and interacting with anionic phospholipid surfaces. S-warfarin is metabolized by CYP2C9. Common genetic polymorphisms in this enzyme can influence warfarin metabolism. Polymorphisms in the C1 subunit of vitamin K reductase (VKORC1) also can affect the susceptibility of the enzyme to warfarin-induced inhibition, thereby influencing warfarin dosage requirements. Warfarin inhibits vitamin K epoxide reductase (VKOR), thereby blocking the γ-carboxylation process. This results in the synthesis of vitamin K–dependent clotting proteins that are only partially γ-carboxylated. Warfarin acts as an anticoagulant because these par­ tially γ-carboxylated proteins have little or no biological activity. The onset of action of warfarin is delayed until the newly synthesized clot­ ting factors with reduced activity gradually replace their fully active counterparts. The antithrombotic effect of warfarin depends on a reduction in the functional levels of factor X and prothrombin, clotting factors that have half-lives of 24 and 72 h, respectively. Because the antithrombotic effect of warfarin is delayed, patients with established thrombosis or at high risk for thrombosis require concomitant treatment with a rapidly acting parenteral anticoagulant, such as heparin, LMWH, or fondaparinux, for at least 5 days. PHARMACOLOGY  Warfarin is a racemic mixture of R and S isomers. Warfarin is rapidly and almost completely absorbed from the gastroin­ testinal tract. Levels of warfarin in the blood peak about 90 min after drug administration. Racemic warfarin has a plasma half-life of 36–42 h, and >97% of circulating warfarin is bound to albumin. Only the small fraction of unbound warfarin is biologically active. Warfarin accumulates in the liver where the two isomers are metab­ olized via distinct pathways. CYP2C9 mediates oxidative metabolism of the more active S isomer (Fig. 123-6). Two relatively common variants, CYP2C9*2 and CYP2C9*3, encode an enzyme with reduced activity. Patients with these variants require lower maintenance doses of war­ farin. Approximately 25% of Caucasians have at least one variant allele of CYP2C9*2 or CYP2C9*3, whereas those variant alleles are less com­ mon in African Americans and Asians (Table 123-8). Heterozygosity for CYP2C9*2 or CYP2C9*3 decreases the warfarin dose requirement by 20–30% relative to that required in subjects with the wild-type CYP2C9*1/*1 alleles, whereas homozygosity for the CYP2C9*2 or CYP2C9*3 alleles reduces the warfarin dose requirement by 50–70%. Consistent with their decreased warfarin dose requirement, subjects with at least one CYP2C9 variant allele are at increased risk for bleed­ ing. Compared with individuals with no variant alleles, the risk of warfarin-associated bleeding is almost twofold higher in CYP2C9*2 or CYP2C9*3 carriers. Polymorphisms in VKORC1 also can influence the anticoagulant response to warfarin. Several genetic variations of VKORC1 are in strong linkage disequilibrium and have been designated as non-A haplotypes. VKORC1 variants are more prevalent than variants of CYP2C9. Asians have the highest prevalence of VKORC1 variants, followed by Caucasians and African Americans (Table 123-8). Poly­ morphisms in VKORC1 likely explain 30% of the variability in war­ farin dose requirements. Compared with VKORC1 non-A/non-A TABLE 123-8  Frequencies of CYP2C9 Genotypes and VKORC1 Haplotypes in Different Populations and their Effect on Warfarin Dose Requirements FREQUENCY, % PERCENTAGE DOSE REDUCTION COMPARED WITH WILD-TYPE CAUCASIANS AFRICAN AMERICANS (A/A) ASIANS (A) GENOTYPE/ HAPLOTYPE CYP2C9 *1/*1 — *1/*2 *1/*3 *2/*2 *2/*3 *3/*3 VKORC1 Non-A/non-A — Non-A/A A/A homozygotes, the warfarin dose requirement decreases by 25 and 50% in A haplotype heterozygotes and homozygotes, respectively. These findings prompted the U.S. Food and Drug Administration (FDA) to amend the prescribing information for warfarin to indicate that lower initiation doses should be considered for patients with CYP2C9 and VKORC1 genetic variants. In addition to genotype data, other perti­ nent patient information has been incorporated into warfarin dosing algorithms. Although such algorithms help predict suitable warfarin doses, it remains unclear whether better dose identification improves patient outcome in terms of reducing hemorrhagic complications or recurrent thrombotic events. In addition to genetic factors, the anticoagulant effect of warfarin is influenced by diet, drugs, and various disease states. Fluctuations in dietary vitamin K intake affect the activity of warfarin. A wide variety of drugs can alter absorption, clearance, or metabolism of warfarin. Because of the variability in the anticoagulant response to warfa­ rin, coagulation monitoring is essential to ensure that a therapeutic response is obtained. MONITORING  Warfarin therapy is most often monitored using the prothrombin time, a test that is sensitive to reductions in the levels of prothrombin, factor VII, and factor X. The test is performed by adding thromboplastin, a reagent that contains tissue factor, phospholipid, and calcium, to citrated plasma and determining the time to clot formation. Thromboplastins vary in their sensitivity to reductions in the levels of the vitamin K–dependent clotting factors. Thus, less sensitive throm­ boplastins will trigger the administration of higher doses of warfarin to achieve a target prothrombin time. This is problematic because higher doses of warfarin increase the risk of bleeding. CHAPTER 123 Antiplatelet, Anticoagulant, and Fibrinolytic Drugs The INR was developed to circumvent many of the problems asso­ ciated with the prothrombin time. To calculate the INR, the patient’s prothrombin time is divided by the mean normal prothrombin time, and this ratio is then multiplied by the international sensitivity index (ISI), which is an index of the sensitivity of the thromboplastin used for prothrombin time determination to reductions in the levels of the vitamin K–dependent clotting factors. Sensitive thromboplastins have an ISI near 1.0. Most current thromboplastins have ISI values that range from 0.9 to 1.4. Although the INR has helped to standardize anticoagulant practice, problems persist. The precision of INR determination varies depend­ ing on reagent-coagulometer combinations. This leads to variability in the INR results. Also complicating INR determination is unreliable reporting of the ISI by thromboplastin manufacturers. Furthermore, every laboratory must establish the mean normal prothrombin time with each new batch of thromboplastin reagent. To accomplish this, the prothrombin time must be measured in fresh plasma samples from at least 20 healthy volunteers using the same coagulometer that is used for patient samples. For most indications, warfarin is administered in doses that produce a target INR of 2.0–3.0. An exception is patients with mechanical heart valves, particularly those in the mitral position or older ball and cage valves in the aortic position, and valves in any position associated with atrial fibrillation, where a target INR of 2.5–3.5 is recommended. Stud­ ies in atrial fibrillation demonstrate an increased risk of cardioembolic stroke when the INR falls below 1.7 and an increase in bleeding with INR values >4.5. These findings highlight the fact that vitamin K antag­ onists have a narrow therapeutic window. In support of this concept, a study in patients receiving long-term warfarin therapy for unprovoked VTE demonstrated a higher rate of recurrent VTE with a target INR of 1.5–1.9 compared with a target INR of 2.0–3.0. DOSING  Warfarin is usually started at a dose of 5–10 mg. Lower doses are used for patients with CYP2C9 or VKORC1 polymorphisms, which affect the pharmacodynamics or pharmacokinetics of warfarin and render patients more sensitive to the drug. The dose is then titrated to achieve the desired target INR. Because of its delayed onset of action, patients with established thrombosis or those at high risk for throm­ bosis are given concomitant initial treatment with a rapidly acting parenteral anticoagulant, such as heparin, LMWH, or fondaparinux. Early prolongation of the INR reflects reduction in the functional levels of factor VII. Consequently, concomitant treatment with the parenteral anticoagulant should be continued until the INR has been therapeutic for at least 2 consecutive days. A minimum 5-day course of parenteral anticoagulation is recommended to ensure that the levels of factor Xa and prothrombin have been reduced into the therapeutic range with warfarin. Because warfarin has a narrow therapeutic window, frequent coagulation monitoring is essential to ensure that a therapeutic anti­ coagulant response is maintained. Even patients with stable warfarin dose requirements should have their INR determined every 3–4 weeks although there are studies suggesting that less frequent monitoring is feasible. More frequent monitoring is necessary when new medica­ tions are introduced because so many drugs enhance or reduce the anticoagulant effects of warfarin and when the dosing regimen has been changed. SIDE EFFECTS  Like all anticoagulants, the major side effect of warfa­ rin is bleeding. A rare complication is skin necrosis. Warfarin crosses the placenta and can cause fetal abnormalities. Consequently, warfarin should not be used during pregnancy. Bleeding  At least half of the bleeding complications with warfarin occur when the INR exceeds the therapeutic range. Bleeding compli­ cations may be mild, such as epistaxis or hematuria, or more severe, such as retroperitoneal or gastrointestinal bleeding. Life-threatening intracranial bleeding can also occur. PART 4 Oncology and Hematology To minimize the risk of bleeding, the INR should be maintained in the therapeutic range. In asymptomatic patients whose INR is between 3.5 and 10, warfarin should be withheld until the INR returns to the therapeutic range. If the INR is over 10, oral vitamin K can be admin­ istered at a dose of 2.5–5 mg, although there is no evidence that doing so reduces the bleeding risk. Higher doses of oral vitamin K (5–10 mg) produce more rapid reversal of the INR but may render patients tem­ porarily resistant to warfarin when the drug is restarted. Patients with an increased INR associated with serious bleeding should be given 5–10 mg of vitamin K by slow IV infusion. Addi­ tional vitamin K should be given until the INR is in the normal range. Treatment with vitamin K should be supplemented with four-factor prothrombin complex concentrate, which contains all four vitamin K– dependent clotting proteins. Prothrombin complex concentrate nor­ malizes the INR more rapidly than transfusion of fresh-frozen plasma. Warfarin-treated patients who experience bleeding when their INR is in the therapeutic range require investigation into the cause of the bleeding. Those with gastrointestinal or genitourinary bleeding often have underlying disorders. Skin Necrosis  A rare complication of warfarin, skin necrosis usually is seen 2–5 days after initiation of therapy. Well-demarcated erythema­ tous lesions form on the thighs, buttocks, breasts, or toes. Typically, the center of the lesion becomes progressively necrotic. Examination of skin biopsies taken from the border of these lesions reveals thrombi in the microvasculature. Warfarin-induced skin necrosis is seen in patients with congenital or acquired deficiencies of protein C or protein S. Initiation of warfarin therapy in these patients produces a precipitous fall in plasma levels of proteins C or S, thereby eliminating this important anticoagulant path­ way before warfarin exerts an antithrombotic effect through lowering of the functional levels of factor X and prothrombin. The resultant pro­ coagulant state triggers thrombosis. Why the thrombosis is localized to the microvasculature of fatty tissues is unclear. Treatment involves discontinuation of warfarin and reversal with vitamin K, if needed. An alternative anticoagulant, such as heparin or LMWH, should be given in patients with thrombosis. Protein C con­ centrate can be given to protein C–deficient patients to accelerate heal­ ing of the skin lesions; fresh-frozen plasma may be of value if protein C concentrate is unavailable and for those with protein S deficiency. Occasionally, skin grafting is necessary when there is extensive skin loss. Because of the potential for skin necrosis, patients with known protein C or protein S deficiency require overlapping treatment with a parenteral anticoagulant when initiating warfarin therapy. Warfarin should be started in low doses in these patients, and the parenteral anticoagulant should be continued until the INR is therapeutic for at least 2–3 consecutive days. Alternatively, treatment with rivaroxaban or apixaban could be given, although there is limited information about their efficacy and safety in patients with severe protein C or S deficiency. Pregnancy  Warfarin crosses the placenta and can cause fetal abnor­ malities or bleeding. The fetal abnormalities include a characteristic embryopathy, which consists of nasal hypoplasia and stippled epiphy­ ses. The risk of embryopathy is highest if warfarin is given in the first trimester of pregnancy. Central nervous system abnormalities can also occur with exposure to warfarin at any time during pregnancy. Finally, maternal administration of warfarin produces an anticoagulant effect in the fetus that can cause bleeding. This is of particular concern at delivery when trauma to the head during passage through the birth canal can lead to intracranial bleeding. Because of these potential prob­ lems, warfarin is contraindicated in pregnancy, particularly in the first and third trimesters. Instead, heparin, LMWH, or fondaparinux can be given during pregnancy for prevention or treatment of thrombosis. Warfarin does not pass into the breast milk. Consequently, warfarin can safely be given to nursing mothers. Special Problems  Patients with antiphospholipid syndrome and those who need urgent or elective surgery present special challenges. Although observational studies suggested that patients with thrombo­ sis complicating antiphospholipid syndrome required higher intensity warfarin regimens to prevent recurrent thromboembolic events, two randomized trials showed that targeting an INR of 2.0–3.0 is as effec­ tive as higher intensity treatment and produces less bleeding. Moni­ toring warfarin therapy can be problematic in patients with the lupus anticoagulant because it prolongs the baseline INR; factor X levels can be used instead of the INR in such patients. There is no need to stop warfarin before procedures associated with a low risk of bleeding; these include dental cleaning, simple dental extraction, cataract surgery, or skin biopsy. For procedures associated with a moderate or high risk of bleeding, warfarin should be stopped 5 days before the procedure to allow the INR to return to normal lev­ els. Patients at high risk for thrombosis, such as those with mechanical heart valves, can be bridged with once- or twice-daily SC injections of LMWH when the INR falls to <2.0. The last dose of LMWH should be given 12–24 h before the procedure, depending on whether LMWH is administered twice or once daily. After the procedure, treatment with warfarin can be restarted. Direct Oral Anticoagulants  The direct oral anticoagulants (DOACs) include dabigatran, which inhibits thrombin, and rivar­ oxaban, apixaban, and edoxaban, which inhibit factor Xa. These drugs have a rapid onset and offset of action and have half-lives that permit once- or twice-daily administration. Designed to produce a predictable level of anticoagulation, the DOACs are more convenient to administer than warfarin because they are given in fixed doses without routine coagulation monitoring. MECHANISM OF ACTION  The DOACs are small molecules that bind reversibly to the active site of their target enzyme. Table 123-9 sum­ marizes the distinct pharmacologic properties of these agents. INDICATIONS  All four DOACs are licensed for stroke prevention in patients with atrial fibrillation except those with mechanical heart valves or severe rheumatic mitral valve disease, and for treatment of VTE. Dabigatran, rivaroxaban, and apixaban are licensed for throm­ boprophylaxis after elective hip or knee arthroplasty; edoxaban is only licensed for this indication in Japan. Finally, low-dose rivaroxaban is licensed for use with aspirin for secondary prevention in patients with coronary or peripheral artery disease. DOSING  For prevention of stroke in patients with atrial fibrillation, rivaroxaban is given at a dosage of 20 mg once daily, with a reduction to 15 mg once daily in patients with a creatinine clearance of 15–49 mL/ min; dabigatran is given at a dosage of 150 mg twice daily, with a reduction to 75 mg twice daily in those with a creatinine clearance of 15–30 mL/min; apixaban is given at a dosage of 5 mg twice daily, with a reduction to 2.5 mg twice daily for patients with at least two of the TABLE 123-9  Comparison of the Pharmacologic Properties of the Direct Oral Anticoagulants CHARACTERISTIC RIVAROXABAN APIXABAN EDOXABAN DABIGATRAN Target Factor Xa Factor Xa Factor Xa Thrombin Prodrug No No No Yes Bioavailability 80% 60% 50% 6% Dosing qd (bid) bid qd bid (qd) Half-life 7–11 h 12 h 9–11 h 12–17 h Renal excretion 33% (66%) 25% 35% 80% Interactions 3A4/P-gp 3A4/P-gp P-gp P-gp Abbreviations: bid, twice a day; P-gp, P-glycoprotein; qd, once a day. “ABC” criteria (i.e., age >80 years, body weight <60 kg, and creatinine >1.5 g/dL); and edoxaban is given at a dosage of 60 mg once daily for patients with a creatinine clearance of 50–95 mL/min and with a reduction to 30 mg once daily for patients with any one of the follow­ ing criteria: creatinine clearance of 15–50 mL/min, body weight of 60 kg or less, or use of potent P-glycoprotein inhibitors, such as vera­ pamil or quinidine. At doses of 15 or 20 mg once daily, rivaroxaban must be administered with food to enhance absorption. Apixaban and edoxaban can be given with or without food. Administration of dabi­ gatran with food may reduce dyspepsia. For treatment of VTE, dabigatran and edoxaban are started after patients have received at least a 5-day course of treatment with a par­ enteral anticoagulant such as LMWH. Dabigatran is given at a dose of 150 mg twice daily provided the creatinine clearance is >30 mL/min. The dosage regimen for edoxaban is identical to that used in patients with atrial fibrillation. Rivaroxaban and apixaban can be given in alloral regimens; rivaroxaban is started at a dose of 15 mg twice daily for 21 days and is then reduced to 20 mg once daily thereafter, whereas apixaban is started at a dose of 10 mg twice daily for 7 days and is then reduced to 5 mg twice daily thereafter. For secondary VTE prevention after 6 months of full-dose treatment, the dosage of apixaban can be lowered to 2.5 mg twice daily while the dose of rivaroxaban can be lowered to 10 mg once daily, doses that have safety profiles like those of placebo and aspirin, respectively. Thromboprophylaxis after elective hip or knee replacement surgery is started after surgery and is often continued for 30 days in patients undergoing hip replacement and for 10–14 days in patients undergo­ ing knee replacement. Dabigatran is given at a dose of 220 mg once daily, whereas rivaroxaban and apixaban are given at doses of 10 mg once daily and 2.5 mg twice daily, respectively. In lower risk patients undergoing hip or knee replacement surgery, a 5-day course of rivar­ oxaban followed by a 30-day course of aspirin at a dose of 81 mg daily appears to be as effective and safe as extended thromboprophylaxis with rivaroxaban. For secondary prevention of adverse cardiac or limb events in patients with coronary or peripheral artery disease, rivaroxaban is given at a dose of 2.5 mg twice daily on top of aspirin (81 or 100 mg once daily). MONITORING  Although designed to be administered without routine monitoring, there are situations where determination of the anticoagu­ lant activity of the DOACs can be helpful. These include assessment of adherence, detection of accumulation or overdose, identification of bleeding mechanisms, and determination of activity before surgery, intervention, or reversal. For qualitative assessment of anticoagulant activity, the prothrombin time can be used for factor Xa inhibitors and the aPTT for dabigatran. Rivaroxaban and edoxaban prolong the prothrombin time more than apixaban. In fact, because apixaban has such a limited effect on the prothrombin time, anti–factor Xa assays are needed to assess its activity. The effect of the drugs on tests of coagula­ tion varies depending on the time that the blood is drawn relative to the timing of the last dose of the drug and the reagents used to perform the tests. Chromogenic anti–factor Xa assays and the diluted thrombin clotting time or ecarin clot time with appropriate calibrators provide quantitative assays to measure the plasma levels of the factor Xa inhibi­ tors and dabigatran, respectively. SIDE EFFECTS  Like all anticoagulants, bleeding is the most com­ mon side effect of the DOACs. The DOACS are associated with less intracranial bleeding than warfarin, but the higher dose regimens of dabigatran, rivaroxaban, and edoxaban are associated with more gas­ trointestinal bleeding. Dyspepsia occurs in up to 10% of patients treated with dabigatran; this problem improves with time and can be minimized by administer­ ing the drug with food. Dyspepsia is rare with rivaroxaban, apixaban, and edoxaban. CHAPTER 123 PERIPROCEDURAL MANAGEMENT  Like warfarin, the DOACs must be stopped before procedures associated with a moderate or high risk of bleeding. The drugs should be held for 1–2 days, or longer if renal function is impaired. Assessment of residual anticoagulant activity before procedures associated with a high bleeding risk is prudent. Antiplatelet, Anticoagulant, and Fibrinolytic Drugs MANAGEMENT OF BLEEDING  With minor bleeding, withholding one or two doses of drug is usually sufficient. With more serious bleeding, the approach is like that with warfarin, except that vitamin K adminis­ tration is of no benefit; the anticoagulant and any long-acting antiplate­ let drugs should be withheld, the patient should be resuscitated with fluids and blood products as necessary, and the bleeding site should be identified and managed. Coagulation testing or measurement of the DOAC level will determine the extent of anticoagulation, and renal function should be assessed so that the half-life of the drug can be calculated. Timing of the last dose of anticoagulant is important; in cases of overdose, oral activated charcoal may help prevent absorption of drug administered in the past 4 h. If >24 h have elapsed since the last intake, the DOAC is unlikely to be responsible for the bleeding unless there is marked impairment of renal function. Anticoagulant reversal should be considered if bleeding continues despite supportive measures or if the bleeding is life-threatening or occurs in a critical organ (e.g., intracranial) or in a closed space (e.g., the pericardium or retroperitoneum). Idarucizumab is licensed for dabigatran reversal in such patients or in those requiring urgent sur­ gery or intervention. A humanized antibody fragment, idarucizumab, binds dabigatran with high affinity to form an essentially irreversible complex that is cleared by the kidneys. Idarucizumab is given intrave­ nously as a 5-g bolus and is supplied in a box containing two 50-mL vials, each containing 2.5 g of idarucizumab. Idarucizumab rapidly reverses the anticoagulant effects of dabigatran and normalizes the aPTT, diluted thrombin time, or ecarin clot time. Andexanet alfa is available for reversal of rivaroxaban and apixaban. A recombinant variant of factor Xa without catalytic activity, andexanet serves as a decoy to sequester oral factor Xa inhibitors until they are cleared from the circulation. Low- or high-dose IV andexanet regimens are used. The low-dose regimen starts with a bolus of 400 mg followed by an infusion of 4 mg/min for up to 120 min, whereas the high-dose regi­ men starts with a bolus of 800 mg followed by an infusion of 8 mg/min for up to 120 min. The low-dose regimen is used for reversal of doses of rivaroxaban or apixaban of 10 mg or 5 mg or less, respectively, or for any dose of rivaroxaban or apixaban if the last dose was taken >8 h before presentation. The high-dose regimen is used to reverse rivaroxa­ ban or apixaban doses over 10 and 5 mg, respectively, if the last dose was taken <8 h since presentation, or if the timing of the last dose of rivaroxaban or apixaban is unknown. Andexanet alfa is expensive and is not available in all hospitals. Because of its cost, andexanet alfa is often reserved for reversal in patients with life-threatening bleeds such intracranial hemorrhage or bleeds into a closed space such as retroperitoneal or pericardial bleeds. If andexanet is unavailable, the results of prospective cohort studies suggest that four-factor prothrombin complex concentrate (25–50 units/kg) also is effective at restoring hemostasis. If there is continued bleeding, acti­ vated prothrombin complex concentrate (50 units/kg) or recombinant factor VIIa (90 μg/kg) can be considered. Neither andexanet alfa nor four-factor prothrombin complex con­ centrate has been evaluated for reversal in patients requiring urgent surgery or intervention. Furthermore, andexanet alfa not only reverses oral factor Xa inhibitors but also reverses heparin and LMWH. This could be problematic in patients who require cardiac surgery or vas­ cular surgery, procedures where heparin is used routinely. To circum­ vent this problem, most surgical procedures and interventions can be undertaken without reversal, and four-factor prothrombin complex concentrate can be given if necessary. For patients requiring surgery to stop bleeding such as those with a ruptured aortic aneurysm or with bleeding secondary to polytrauma, upfront four-factor prothrombin concentrate administration can be considered. PREGNANCY  As small molecules, the DOACs pass through the pla­ centa. Consequently, these agents are contraindicated in pregnancy, and when used by women of childbearing potential, appropriate con­ traception is important. DOACs should be avoided in nursing mothers because small amounts have been found in breast milk. PART 4 Oncology and Hematology FIBRINOLYTIC DRUGS ■ ■ROLE OF FIBRINOLYTIC THERAPY Fibrinolytic drugs are used to degrade thrombi and are administered systemically or can be delivered via catheters directly into the substance of the thrombus. Systemic delivery is used for treatment of acute MI, acute ischemic stroke, and most cases of massive PE. The goal of ther­ apy is to produce rapid thrombus dissolution, thereby restoring blood flow. In the coronary circulation, restoration of blood flow reduces morbidity and mortality rates by limiting myocardial damage, whereas in the cerebral circulation, rapid thrombus dissolution decreases the neuronal death and brain infarction that produce irreversible brain injury. For patients with massive PE, the goal of thrombolytic therapy is to restore pulmonary artery perfusion. Peripheral arterial thrombi and thrombi in the proximal deep veins of the leg are most often treated using catheter-directed thrombolytic therapy. Catheters with multiple side holes can be used to enhance drug delivery. In some cases, intravascular devices that fragment and extract the thrombus are used to hasten treatment. These devices can be used alone or in conjunction with fibrinolytic drugs. ■ ■MECHANISM OF ACTION Currently approved fibrinolytic agents include streptokinase; acylated plasminogen streptokinase activator complex (anistreplase); urokinase; recombinant tissue-type plasminogen activator (rtPA), which is also known as alteplase or activase; and two recombinant derivatives of rtPA, tenecteplase and reteplase. Of these, streptokinase, anistreplase, and urokinase are no longer available in the United States. All these agents act by converting plasminogen, the zymogen, to plasmin, the active enzyme (Fig. 123-7). Plasmin then degrades the fibrin matrix of thrombi and produces soluble fibrin degradation products. Endogenous fibrinolysis is regulated at two levels. Plasminogen activator inhibitors, particularly the type 1 form (PAI-1), prevent excessive plasminogen activation by regulating the activity of tPA and urokinase-type plasminogen activator (uPA). Once plasmin is gener­ ated, it is regulated by plasmin inhibitors, the most important of which is α2-antiplasmin. The plasma concentration of plasminogen is twofold higher than that of α2-antiplasmin. Consequently, with pharmacologic doses of plasminogen activators, the concentration of plasmin that is generated can exceed that of α2-antiplasmin. In addition to degrading fibrin, unregulated plasmin can also degrade fibrinogen and other clot­ ting factors. This process, which is known as the systemic lytic state, Plasminogen activators PAI-1 Plasmin Plasminogen α2-antiplasmin Fibrin degradation products Fibrin FIGURE 123-7  The fibrinolytic system and its regulation. Plasminogen activators convert plasminogen to plasmin. Plasmin then degrades fibrin into soluble fibrin degradation products. The system is regulated at two levels. Type 1 plasminogen activator inhibitor (PAI-1) inhibits the plasminogen activators, whereas α2antiplasmin serves as the major inhibitor of plasmin. reduces the hemostatic potential of the blood and increases the risk of bleeding. The endogenous fibrinolytic system is geared to localize plasmin generation to the fibrin surface. Both plasminogen and tPA bind to fibrin to form a ternary complex that promotes efficient plasminogen activation. In contrast to free plasmin, plasmin generated on the fibrin surface is relatively protected from inactivation by α2-antiplasmin, a feature that promotes fibrin dissolution. Furthermore, C-terminal lysine residues, exposed as plasmin degrades fibrin, provide bind­ ing sites for additional plasminogen and tPA molecules. This creates positive feedback that enhances plasmin generation. When used phar­ macologically, the various plasminogen activators capitalize on these mechanisms to a lesser or greater extent. Plasminogen activators that preferentially activate fibrin-bound plasminogen are considered fibrin-specific. In contrast, nonspecific plasminogen activators do not discriminate between fibrin-bound and circulating plasminogen. Activation of circulating plasminogen results in the generation of unopposed plasmin that can trigger the systemic lytic state. Alteplase and its derivatives are fibrin-specific plasminogen activators, whereas streptokinase, anistreplase, and urokinase are non­ specific agents. ■ ■STREPTOKINASE Unlike other plasminogen activators, streptokinase is not an enzyme and does not directly convert plasminogen to plasmin. Instead, strep­ tokinase forms a 1:1 stoichiometric complex with plasminogen. Forma­ tion of this complex induces a conformational change in plasminogen that exposes its active site (Fig. 123-8). The streptokinase-plasminogen complex then converts additional plasminogen to plasmin. S Plasminogen Streptokinase S Plasminogen Streptokinase FIGURE 123-8  Mechanism of action of streptokinase. Streptokinase binds to plasminogen and induces a conformational change in plasminogen that exposes its active site. The streptokinase/plasmin(ogen) complex then serves as the activator of additional plasminogen. Streptokinase has no affinity for fibrin, and the streptokinaseplasminogen complex activates both free and fibrin-bound plasmino­ gen. Activation of circulating plasminogen generates enough plasmin to overwhelm α2-antiplasmin. Unopposed plasmin not only degrades fibrin in the occlusive thrombus but also induces a systemic lytic state. When given systemically to patients with acute MI, streptokinase reduces mortality. For this indication, the drug is usually given as an IV infusion of 1.5 million units over 30–60 min. Patients who receive streptokinase can develop antibodies against the drug, as can patients with prior streptococcal infection. These antibodies can reduce the effectiveness of streptokinase. Allergic reactions occur in ~5% of patients treated with streptoki­ nase. These may manifest as a rash, fever, chills, and rigors. Although anaphylactic reactions can occur, these are rare. Transient hypotension is common with streptokinase and has been attributed to plasmin- mediated release of bradykinin from kininogen. The hypotension usu­ ally responds to leg elevation and administration of IV fluids and low doses of vasopressors, such as dopamine or norepinephrine. ■ ■ANISTREPLASE To generate this drug, streptokinase is combined with equimolar amounts of Lys-plasminogen, a plasmin-cleaved form of plasminogen with a Lys residue at its N terminal. The active site of Lys-plasminogen that is exposed upon combination with streptokinase is then masked with an anisoyl group. After IV infusion, the anisoyl group is slowly removed by deacylation, giving the complex a half-life of ~100 min. This allows drug administration via a single bolus infusion. Although it is more convenient to administer, anistreplase offers few mechanistic advantages over streptokinase. Like streptokinase, anistreplase does not distinguish between fibrin-bound and circulat­ ing plasminogen. Consequently, it too produces a systemic lytic state. Likewise, allergic reactions and hypotension are just as frequent with anistreplase as they are with streptokinase. When anistreplase was compared with alteplase in patients with acute MI, reperfusion was obtained more rapidly with alteplase than with anis­ treplase. Improved reperfusion was associated with a trend toward better clinical outcomes and reduced mortality rate with alteplase. These results and the high cost of anistreplase dampened the enthusiasm for its use. ■ ■UROKINASE Urokinase is a two-chain serine protease derived from cultured fetal kidney cells with a molecular weight of 34,000. Urokinase converts plasminogen to plasmin directly by cleaving the Arg560-Val561 bond. Unlike streptokinase, urokinase is not immunogenic, and allergic reac­ tions are rare. Urokinase produces a systemic lytic state because it does not discriminate between fibrin-bound and circulating plasminogen. Despite many years of use, urokinase has never been systemically evaluated for coronary thrombolysis. Instead, urokinase is often employed for catheter-directed lysis of thrombi in the deep veins or the peripheral arteries. Because of production problems, urokinase is no longer available. ■ ■ALTEPLASE A recombinant form of single-chain tPA, alteplase has a molecular weight of 68,000. Alteplase is rapidly converted into its two-chain form by plasmin. Although single- and two-chain forms of tPA have equiva­ lent activity in the presence of fibrin, in its absence, single-chain tPA has 10-fold lower activity. Alteplase consists of five discrete domains (Fig. 123-9); the N-terminal A chain of two-chain alteplase contains four of these domains. Residues 4 through 50 make up the finger domain, a region that resembles the finger domain of fibronectin; residues 50 through 87 are homologous with epidermal growth factor, whereas residues 92 through 173 and 180 through 261, which have homology to the kringle domains of plasminogen, are designated as the first and second kringle, respectively. The fifth alteplase domain is the protease domain; it is located on the C-terminal B chain of two-chain alteplase. The interaction of alteplase with fibrin is mediated by the finger domain and, to a lesser extent, by the second kringle domain. The tPA F EGF K1 K2 P KHRR AAAA F EGF K1 K2 P TNK-tPA K2 P r-PA FIGURE 123-9  Domain structures of alteplase (tPA), tenecteplase (TNK-tPA), and reteplase (r-PA). The finger (F), epidermal growth factor (EGF), first and second kringles (K1 and K2, respectively), and protease (P) domains are illustrated. The glycosylation site (Y) on K1 has been repositioned in tenecteplase to endow it with a longer half-life. In addition, a tetra-alanine substitution in the protease domain renders tenecteplase resistant to type 1 plasminogen activator inhibitor (PAI-1) inhibition. Reteplase is a truncated variant that lacks the F, EGF, and K1 domains. CHAPTER 123 affinity of alteplase for fibrin is considerably higher than that for fibrin­ ogen. Consequently, the catalytic efficiency of plasminogen activation by alteplase is two to three orders of magnitude higher in the presence of fibrin than in the presence of fibrinogen. This phenomenon helps to localize plasmin generation to the fibrin surface. Antiplatelet, Anticoagulant, and Fibrinolytic Drugs Although alteplase preferentially activates plasminogen in the pres­ ence of fibrin, alteplase is not as fibrin selective as was first predicted. Its fibrin specificity is limited because, like fibrin, (DD)E, the major soluble degradation product of cross-linked fibrin, binds alteplase and plasminogen with high affinity. Consequently, (DD)E is as potent as fibrin as a stimulator of plasminogen activation by alteplase. Whereas plasmin generated on the fibrin surface results in thromboly­ sis, plasmin generated on the surface of circulating (DD)E degrades fibrinogen. Fibrinogen degradation results in the accumulation of fragment X, a high-molecular-weight clottable fibrinogen degradation product. Incorporation of fragment X into hemostatic plugs formed at sites of vascular injury renders them susceptible to lysis. This phenom­ enon may contribute to alteplase-induced bleeding. A trial comparing alteplase with streptokinase for treatment of patients with acute MI demonstrated significantly lower mortality with alteplase than with streptokinase, although the absolute difference was small. The greatest benefit was seen in patients age <75 years with anterior MI who presented <6 h after symptom onset. For treatment of acute MI or acute ischemic stroke, alteplase is given as an IV infusion over 60–90 min. The total dose of alteplase usually ranges from 90 to 100 mg. Allergic reactions and hypotension are rare, and alteplase is not immunogenic. ■ ■TENECTEPLASE Tenecteplase is a genetically engineered variant of tPA and was designed to have a longer half-life than tPA and to be resistant to inac­ tivation by PAI-1. To prolong its half-life, a new glycosylation site was added to the first kringle domain (Fig. 123-9). Because addition of this extra carbohydrate side chain reduced fibrin affinity, the existing gly­ cosylation site on the first kringle domain was removed. To render the molecule resistant to inhibition by PAI-1, a tetra-alanine substitution was introduced at residues 296–299 in the protease domain, the region responsible for the interaction of tPA with PAI-1. Tenecteplase is more fibrin-specific than tPA. Although both agents bind to fibrin with similar affinity, the affinity of tenecteplase for (DD) E is significantly lower than that of tPA. Consequently, (DD)E does not stimulate systemic plasminogen activation by tenecteplase to the same extent as tPA. As a result, tenecteplase produces less fibrinogen degradation than tPA. For coronary thrombolysis, tenecteplase is given as a single IV bolus. In a large phase III trial that enrolled >16,000 patients, the 30-day mor­ tality rate with single-bolus tenecteplase was like that with accelerateddose tPA. Although rates of intracranial hemorrhage were similar with both treatments, patients given tenecteplase had fewer noncerebral bleeds and a reduced need for blood transfusions than those treated with tPA. The improved safety profile of Tenecteplase likely reflects its enhanced fibrin specificity. ■ ■RETEPLASE Reteplase is a single-chain, recombinant tPA derivative that lacks the finger, epidermal growth factor, and first kringle domains (Fig. 123-9). This truncated derivative has a molecular weight of 39,000. The affinity of reteplase for fibrin is lower than that of tPA likely because reteplase lacks the finger domain. Because it is produced in Escherichia coli, reteplase is not glycosylated. This endows it with a plasma half-life lon­ ger than that of tPA. Consequently, reteplase is given as two IV boluses, which are separated by 30 min. Clinical trials have demonstrated that reteplase is at least as effective as streptokinase for treatment of acute MI, but the agent is not superior to tPA. CONCLUSIONS AND FUTURE DIRECTIONS Thrombosis involves a complex interplay among the vessel wall, platelets, the coagulation system, and the fibrinolytic pathways. Acti­ vation of coagulation also triggers inflammatory pathways that may exacerbate thrombosis. A better understanding of the biochemistry of blood coagulation and advances in structure-based drug design have identified new targets and resulted in the development of novel anti­ thrombotic drugs. Well-designed clinical trials have provided detailed information on which drugs to use and when to use them. Despite these advances, however, thromboembolic disorders remain a major cause of morbidity and mortality. Therefore, the search for better and safer targets continues. PART 4 Oncology and Hematology ■ ■FURTHER READING Arepally GM, Padmanabhan A: Heparin-induced thrombocytope­ nia: A focus on thrombosis. Arterioscler Thromb Vasc Biol 41:141, 2021. Berger JS: Aspirin for primary prevention—time to rethink our approach. JAMA Netw Open 5:e2210144, 2022. Fei Y et al: Efficacy and safety of newer P2Y12 inhibitors for acute coro­ nary syndrome: A network meta-analysis. Sci Rep 10:16794, 2020. Greinacher A et al: Thrombotic thrombocytopenia after ChAdOx1 nCov-19 vaccination. N Engl J Med 384:2092, 2021. Hao C et al: Low molecular weight heparins and their clinical applica­ tions. Prog Mol Biol Transl Sci 163:21, 2019. Phipps MS, Cronin CA: Management of acute ischemic stroke. BMJ 368:l6983, 2020. Prince M, Wenham T: Heparin-induced thrombocytopenia. Postgrad Med J 94:453, 2018. Rivera-Caravaca JM et al: Treatment strategies for patients with atrial fibrillation and anticoagulant-associated intracranial hemor­ rhage: An overview of the pharmacotherapy. Expert Opin Pharma­ cother 21:1867, 2020. Satoh K et al: Recent advances in the understanding of thrombosis. Arterioscler Thromb Vasc Biol 39:e159, 2019. Scully M et al: Pathologic antibodies to platelet factor 4 after ChAdOx1 nCoV-19 vaccination. N Engl J Med 384:2202, 2021. Steffel J et al: The COMPASS Trial: Net clinical benefit of low-dose rivaroxaban plus aspirin as compared with aspirin in patients with chronic vascular disease. Circulation 142:40, 2020. White K et al: New agents for DOAC reversal: a practical management review. Br J Cardiol 29:1, 2022.