Late Effects of Treatment for Childhood Cancer (PDQ®): Treatment - Health Professional Information [NCI]

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Late Effects of Treatment for Childhood Cancer (PDQ®): Treatment - Health Professional Information [NCI]

This information is produced and provided by the National Cancer Institute (NCI). The information in this topic may have changed since it was written. For the most current information, contact the National Cancer Institute via the Internet web site at http://cancer.gov or call 1-800-4-CANCER.

Late Effects of Treatment for Childhood Cancer

General Information

During the past five decades, dramatic progress has been made in the development of curative therapy for pediatric malignancies. Long-term survival into adulthood is the expectation for 80% of children with access to contemporary therapies for pediatric malignancies.[1] The therapy responsible for this survival can also produce adverse long-term health-related outcomes, referred to as "late effects," that manifest months to years after completion of cancer treatment. A variety of approaches have been used to advance knowledge about the very long-term morbidity associated with childhood cancer and its contribution to early mortality. These initiatives have utilized a spectrum of resources including investigation of data from population-based registries, self-reported outcomes provided through large-scale cohort studies, and information collected from medical assessments. Studies reporting outcomes in survivors who have been well characterized in regards to clinical status and treatment exposures, and comprehensively ascertained for specific effects through medical assessments, typically provide the highest quality of data to establish the occurrence and risk profiles for late cancer treatment-related toxicity. Regardless of study methodology, it is important to consider selection and participation bias of the cohort studies in the context of the findings reported.


Late Effects – Cumulative incidence of chronic health conditions; drawing shows graphs of cumulative incidence and severity of chronic disease among survivors of childhood cancer at 1 to 30 years after original cancer diagnosis, for leukemia, CNS tumor, Hodgkin's disease, non-Hodgkin's lymphoma, Wilms' tumor, neuroblastoma, soft-tissue sarcoma, bone tumor, and the total surviving.
Figure 1. Investigators from the Childhood Cancer Survivor Study (CCSS), a retrospective multi-institutional cohort investigation that has been monitoring health outcomes of more than 20,000 long-term childhood cancer survivors for more than 15 years, estimated a cumulative incidence of 73.4% for at least one chronic health problem (grades 1–5) by age 40 years among the 10,397 adult participants (mean age, 26.6 years); more than 40% will experience a chronic condition that is severe, life-threatening, or fatal (grades 3–5). The risk of specific late effects in an individual is dependent upon the type and location of the cancer and therapeutic interventions undertaken to control the cancer. Oeffinger KC, Mertens AC, Sklar CA, et al.: Chronic health conditions in adult survivors of childhood cancer. N Engl J Med 355 (15): 1572-82, 2006. Copyright © 2006 Massachusetts Medical Society.

Late effects are commonly experienced by adults who have survived childhood cancer and demonstrate an increasing prevalence associated with longer time elapsed from cancer diagnosis. Population-based studies support excess hospital-related morbidity among childhood cancer survivors compared with age- and gender-matched controls.[3,4,5,6,7] Research has clearly demonstrated that late effects contribute to a high burden of morbidity among adults treated for cancer during childhood, with 60% to almost 90% developing one or more chronic health conditions and 20% to 40% experiencing severe or life-threatening complications during adulthood.[2,8,9,10,11] Recognition of late effects, concurrent with advances in cancer biology, radiological sciences, and supportive care, has resulted in a change in the prevalence and spectrum of treatment effects. In an effort to reduce and prevent late effects, contemporary therapy for the majority of pediatric malignancies has evolved to a risk-adapted approach that is assigned based on a variety of clinical, biological, and sometimes genetic factors. With the exception of survivors requiring intensive multimodality therapy for aggressive or refractory/relapsed malignancies, life-threatening treatment effects are relatively uncommon after contemporary therapy in early follow-up (up to 10 years after diagnosis). However, survivors still frequently experience life-altering morbidity related to effects of cancer treatment on endocrine, reproductive, musculoskeletal, and neurologic function.

Mortality

Late effects also contribute to an excess risk of premature death among long-term survivors of childhood cancer. Several studies of very large cohorts of survivors have reported early mortality among individuals treated for childhood cancer compared with age- and gender-matched general population controls. Relapsed/refractory primary cancer remains the most frequent cause of death, followed by excess cause-specific mortality from subsequent primary cancers and cardiac and pulmonary toxicity.[12,13,14,15,16,17,18]; [19][Level of evidence: 3iA] Despite high premature morbidity rates, overall mortality has decreased over time.[20,21] This reduction is related to a decrease in deaths from the primary cancer without an associated increase in mortality from subsequent cancers or treatment-related toxicities. The former reflects improvements in therapeutic efficacy, and the latter reflects changes in therapy made subsequent to studying the causes of late effects. The expectation that mortality rates in survivors will continue to exceed those in the general population is based on the long-term sequelae that are likely to increase with attained age. If patients treated on therapeutic protocols are followed for long periods into adulthood, it will be possible to evaluate the excess lifetime mortality in relation to specific therapeutic interventions.

Previous studies have shown excess late mortality in childhood cancer survivors. In a population-based study in Finland, the long-term mortality risks from major nonmalignant diseases in 5-year survivors of childhood and adolescent and young adult (AYA) cancer diagnosed before age 35 years were evaluated and included more than 6,000 AYA cancer survivors. In this study, standardized mortality rates (SMRs) were 90% higher for nonmalignant diseases (SMR, 1.9; 95% CI, 1.7–2.2) than expected for the entire cohort, with SMRs similarly elevated for patient subgroups with circulatory disease and respiratory disease. These risks remained elevated for Hodgkin and non-Hodgkin lymphoma survivors diagnosed between the ages of 15 and 34 years. The risk of death from respiratory disease was significantly elevated by 140% (SMR, 2.4; 95% CI, 1.3–4.1) in young adult patients diagnosed with cancer between the ages of 20 and 34 years.[22]

Monitoring for Late Effects

Recognition of both acute and late modality–specific toxicity has motivated investigations evaluating the pathophysiology and prognostic factors for cancer treatment–related effects. The results of these studies have played an important role in changing pediatric cancer therapeutic approaches and reducing treatment-related mortality among survivors treated in more recent eras.[20,21] These investigations have also informed the development of risk counseling and health screening recommendations of long-term survivors by identifying the clinical and treatment characteristics of those at highest risk for treatment complications. The common late effects of pediatric cancer encompass several broad domains including growth and development, organ function, reproductive capacity and health of offspring, and secondary carcinogenesis. In addition, survivors of childhood cancer may experience a variety of adverse psychosocial sequelae related to the primary cancer, its treatment, or maladjustment associated with the cancer experience.

Late sequelae of therapy for childhood cancer can be anticipated based on therapeutic exposures, but the magnitude of risk and the manifestations in an individual patient are influenced by numerous factors. Factors that should be considered in the risk assessment for a given late effect include the following:

Tumor-related factors

  • Tumor location.
  • Direct tissue effects.
  • Tumor-induced organ dysfunction.
  • Mechanical effects.

Treatment-related factors

  • Radiation therapy: total dose, fraction size, organ or tissue volume, type of machine energy.
  • Chemotherapy: agent type, dose-intensity, cumulative dose, schedule.
  • Surgery: technique, site.
  • Use of combined modality therapy.
  • Blood product transfusion.
  • Hematopoietic cell transplantation.

Host-related factors

  • Gender.
  • Age at diagnosis.
  • Time from diagnosis/therapy.
  • Developmental status.
  • Genetic predisposition.
  • Inherent tissue sensitivities and capacity for normal tissue repair.
  • Function of organs not affected by cancer treatment.
  • Premorbid health state.
  • Socioeconomic status.
  • Health habits.

Resources to Support Survivor Care

The need for long-term follow-up for childhood cancer survivors is supported by the American Society of Pediatric Hematology/Oncology, the International Society of Pediatric Oncology, the American Academy of Pediatrics, the Children's Oncology Group (COG), and the Institute of Medicine. Specifically, a risk-based medical follow-up is recommended, which includes a systematic plan for lifelong screening, surveillance, and prevention that incorporates risk estimates based on the previous cancer, cancer therapy, genetic predisposition, lifestyle behaviors, and comorbid conditions.[23,24] Part of long-term follow-up should also be focused on appropriate screening of educational and vocational progress. Specific treatments for childhood cancer, especially those that directly impact nervous system structures, may result in sensory, motor, and neurocognitive deficits that may have adverse consequences on functional status, educational attainment, and future vocational opportunities.[25] A Childhood Cancer Survivor Study (CCSS) investigation observed that treatment with cranial radiation doses of 25 Gy or higher was associated with higher odds of unemployment (health related: odds ratio [OR] = 3.47; 95% confidence interval [CI], 2.54–4.74; seeking work: OR = 1.77; 95% CI, 1.15–2.71).[26] Unemployed survivors reported higher levels of poor physical functioning than employed survivors, had lower education and income, and were more likely to be publicly insured than unemployed siblings.[26] These data emphasize the importance of facilitating survivor access to remedial services, which has been demonstrated to have a positive impact on education achievement,[27] which may in turn enhance vocational opportunities.

In addition to risk-based screening for medical late effects, the impact of health behaviors on cancer-related health risks should also be emphasized. Health-promoting behaviors should be stressed for survivors of childhood cancer, as targeted educational efforts appear to be worthwhile.[28,29,30,31] Smoking, excess alcohol use, and illicit drug use increase risk of organ toxicity and, potentially, subsequent neoplasms. Unhealthy dietary practices and sedentary lifestyle may exacerbate treatment-related metabolic and cardiovascular complications. Proactively addressing unhealthy and risky behaviors is pertinent, as several research investigations confirm that long-term survivors use tobacco and alcohol and have inactive lifestyles at higher rates than is ideal given their increased risk of cardiac, pulmonary, and metabolic late effects.[32,33,34]

Unfortunately, the majority of childhood cancer survivors do not receive recommended risk-based care. The CCSS reported that 88.8% of survivors were receiving some form of medical care; however, only 31.5% reported receiving care that focused on their prior cancer (survivor-focused care), and 17.8% reported receiving survivor-focused care that included advice about risk reduction and discussion or ordering of screening tests.[32] Among the same cohort, surveillance for new cases of cancer was very low in survivors at the highest risk for colon, breast, or skin cancer, suggesting that survivors and their physicians need education about their risks and recommended surveillance.[35] Health insurance access appears to play an important role in access to risk-based survivor care. In a related CCSS study, uninsured survivors were less likely than those privately insured to report a cancer-related visit (adjusted relative risk [RR] = 0.83; 95% CI, 0.75–0.91) or a cancer center visit (adjusted RR = 0.83; 95% CI, 0.71–0.98). Uninsured survivors had lower levels of utilization in all measures of care compared with privately insured survivors. In contrast, publicly insured survivors were more likely to report a cancer-related visit (adjusted RR = 1.22; 95% CI, 1.11–1.35) or a cancer center visit (adjusted RR = 1.41; 95% CI, 1.18–1.70) than were privately insured survivors.[36] In a study comparing health care outcomes for long-term survivors of AYA cancer with young adults who have a cancer history, the proportion of uninsured survivors did not differ between the two groups. Subgroups of AYA survivors may be at additional risk for facing health care barriers. Younger survivors (aged 20–29 years), females, nonwhites, and survivors reporting poorer health faced more cost barriers, which may inhibit the early detection of late effects.[37] Overall, lack of health insurance remains a significant concern for survivors of childhood cancer because of health issues, unemployment, and other societal factors. Legislation, like the Health Insurance Portability and Accountability Act legislation, has improved access and retention of health insurance among survivors, although the quality and limitations associated with these policies have not been well studied.[38,39]

Transition of Survivor Care

Transition of care from the pediatric to the adult health care setting is necessary for most childhood cancer survivors in the United States. When available, multidisciplinary long-term follow-up (LTFU) programs in the pediatric cancer center work collaboratively with community physicians to provide care for childhood cancer survivors. This type of shared-care has been proposed as the optimal model to facilitate coordination between the cancer center oncology team and community physician groups providing survivor care.[40] An essential service of LTFU programs is the organization of an individualized survivorship care plan that includes details about therapeutic interventions undertaken for childhood cancer and their potential health risks, personalized health screening recommendations, and information about lifestyle factors that modify risks. For survivors who have not been provided with this information, the COG offers a template that can be used by survivors to organize a personal treatment summary (see the COG Survivorship Guidelines Appendix 1).

To facilitate survivor and provider access to succinct information to guide risk-based care, COG investigators have organized a compendium of exposure- and risk-based health surveillance recommendations with the goal of standardizing the care of childhood cancer survivors.[23] The COG Long-Term Follow-Up Guidelines for Survivors of Childhood, Adolescent and Young Adult Cancers are appropriate for asymptomatic survivors presenting for routine exposure-based medical follow-up 2 or more years after completion of therapy. Patient education materials called ‘‘Health Links'' provide detailed information on guideline-specific topics to enhance health maintenance and promotion among this population of cancer survivors.[41] Multidisciplinary system-based (e.g., cardiovascular, neurocognitive, and reproductive) task forces who are responsible for monitoring the literature, evaluating guideline content, and providing recommendations for guideline revisions as new information becomes available have also published several comprehensive reviews that address specific late effects of childhood cancer.[42,43,44,45,46,47,48,49,50] Information concerning late effects is summarized in tables throughout this summary.

References:

1. Jemal A, Siegel R, Xu J, et al.: Cancer statistics, 2010. CA Cancer J Clin 60 (5): 277-300, 2010 Sep-Oct.
2. Oeffinger KC, Mertens AC, Sklar CA, et al.: Chronic health conditions in adult survivors of childhood cancer. N Engl J Med 355 (15): 1572-82, 2006.
3. Lorenzi MF, Xie L, Rogers PC, et al.: Hospital-related morbidity among childhood cancer survivors in British Columbia, Canada: report of the childhood, adolescent, young adult cancer survivors (CAYACS) program. Int J Cancer 128 (7): 1624-31, 2011.
4. Mols F, Helfenrath KA, Vingerhoets AJ, et al.: Increased health care utilization among long-term cancer survivors compared to the average Dutch population: a population-based study. Int J Cancer 121 (4): 871-7, 2007.
5. Sun CL, Francisco L, Kawashima T, et al.: Prevalence and predictors of chronic health conditions after hematopoietic cell transplantation: a report from the Bone Marrow Transplant Survivor Study. Blood 116 (17): 3129-39; quiz 3377, 2010.
6. Rebholz CE, Reulen RC, Toogood AA, et al.: Health care use of long-term survivors of childhood cancer: the British Childhood Cancer Survivor Study. J Clin Oncol 29 (31): 4181-8, 2011.
7. Kurt BA, Nolan VG, Ness KK, et al.: Hospitalization rates among survivors of childhood cancer in the Childhood Cancer Survivor Study cohort. Pediatr Blood Cancer 59 (1): 126-32, 2012.
8. Geenen MM, Cardous-Ubbink MC, Kremer LC, et al.: Medical assessment of adverse health outcomes in long-term survivors of childhood cancer. JAMA 297 (24): 2705-15, 2007.
9. Wasilewski-Masker K, Mertens AC, Patterson B, et al.: Severity of health conditions identified in a pediatric cancer survivor program. Pediatr Blood Cancer 54 (7): 976-82, 2010.
10. Stevens MC, Mahler H, Parkes S: The health status of adult survivors of cancer in childhood. Eur J Cancer 34 (5): 694-8, 1998.
11. Garrè ML, Gandus S, Cesana B, et al.: Health status of long-term survivors after cancer in childhood. Results of an uniinstitutional study in Italy. Am J Pediatr Hematol Oncol 16 (2): 143-52, 1994.
12. Armstrong GT, Liu Q, Yasui Y, et al.: Late mortality among 5-year survivors of childhood cancer: a summary from the Childhood Cancer Survivor Study. J Clin Oncol 27 (14): 2328-38, 2009.
13. Bhatia S, Robison LL, Francisco L, et al.: Late mortality in survivors of autologous hematopoietic-cell transplantation: report from the Bone Marrow Transplant Survivor Study. Blood 105 (11): 4215-22, 2005.
14. Dama E, Pastore G, Mosso ML, et al.: Late deaths among five-year survivors of childhood cancer. A population-based study in Piedmont Region, Italy. Haematologica 91 (8): 1084-91, 2006.
15. Lawless SC, Verma P, Green DM, et al.: Mortality experiences among 15+ year survivors of childhood and adolescent cancers. Pediatr Blood Cancer 48 (3): 333-8, 2007.
16. MacArthur AC, Spinelli JJ, Rogers PC, et al.: Mortality among 5-year survivors of cancer diagnosed during childhood or adolescence in British Columbia, Canada. Pediatr Blood Cancer 48 (4): 460-7, 2007.
17. Möller TR, Garwicz S, Perfekt R, et al.: Late mortality among five-year survivors of cancer in childhood and adolescence. Acta Oncol 43 (8): 711-8, 2004.
18. Tukenova M, Guibout C, Hawkins M, et al.: Radiation therapy and late mortality from second sarcoma, carcinoma, and hematological malignancies after a solid cancer in childhood. Int J Radiat Oncol Biol Phys 80 (2): 339-46, 2011.
19. Reulen RC, Winter DL, Frobisher C, et al.: Long-term cause-specific mortality among survivors of childhood cancer. JAMA 304 (2): 172-9, 2010.
20. Armstrong GT, Pan Z, Ness KK, et al.: Temporal trends in cause-specific late mortality among 5-year survivors of childhood cancer. J Clin Oncol 28 (7): 1224-31, 2010.
21. Yeh JM, Nekhlyudov L, Goldie SJ, et al.: A model-based estimate of cumulative excess mortality in survivors of childhood cancer. Ann Intern Med 152 (7): 409-17, W131-8, 2010.
22. Prasad PK, Signorello LB, Friedman DL, et al.: Long-term non-cancer mortality in pediatric and young adult cancer survivors in Finland. Pediatr Blood Cancer 58 (3): 421-7, 2012.
23. Landier W, Bhatia S, Eshelman DA, et al.: Development of risk-based guidelines for pediatric cancer survivors: the Children's Oncology Group Long-Term Follow-Up Guidelines from the Children's Oncology Group Late Effects Committee and Nursing Discipline. J Clin Oncol 22 (24): 4979-90, 2004.
24. Oeffinger KC, Hudson MM: Long-term complications following childhood and adolescent cancer: foundations for providing risk-based health care for survivors. CA Cancer J Clin 54 (4): 208-36, 2004 Jul-Aug.
25. Hudson MM, Mulrooney DA, Bowers DC, et al.: High-risk populations identified in Childhood Cancer Survivor Study investigations: implications for risk-based surveillance. J Clin Oncol 27 (14): 2405-14, 2009.
26. Kirchhoff AC, Leisenring W, Krull KR, et al.: Unemployment among adult survivors of childhood cancer: a report from the childhood cancer survivor study. Med Care 48 (11): 1015-25, 2010.
27. Mitby PA, Robison LL, Whitton JA, et al.: Utilization of special education services and educational attainment among long-term survivors of childhood cancer: a report from the Childhood Cancer Survivor Study. Cancer 97 (4): 1115-26, 2003.
28. Cox CL, McLaughlin RA, Rai SN, et al.: Adolescent survivors: a secondary analysis of a clinical trial targeting behavior change. Pediatr Blood Cancer 45 (2): 144-54, 2005.
29. Cox CL, McLaughlin RA, Steen BD, et al.: Predicting and modifying substance use in childhood cancer survivors: application of a conceptual model. Oncol Nurs Forum 33 (1): 51-60, 2006.
30. Cox CL, Montgomery M, Oeffinger KC, et al.: Promoting physical activity in childhood cancer survivors: results from the Childhood Cancer Survivor Study. Cancer 115 (3): 642-54, 2009.
31. Cox CL, Montgomery M, Rai SN, et al.: Supporting breast self-examination in female childhood cancer survivors: a secondary analysis of a behavioral intervention. Oncol Nurs Forum 35 (3): 423-30, 2008.
32. Nathan PC, Ford JS, Henderson TO, et al.: Health behaviors, medical care, and interventions to promote healthy living in the Childhood Cancer Survivor Study cohort. J Clin Oncol 27 (14): 2363-73, 2009.
33. Schultz KA, Chen L, Chen Z, et al.: Health and risk behaviors in survivors of childhood acute myeloid leukemia: a report from the Children's Oncology Group. Pediatr Blood Cancer 55 (1): 157-64, 2010.
34. Tercyak KP, Donze JR, Prahlad S, et al.: Multiple behavioral risk factors among adolescent survivors of childhood cancer in the Survivor Health and Resilience Education (SHARE) program. Pediatr Blood Cancer 47 (6): 825-30, 2006.
35. Nathan PC, Ness KK, Mahoney MC, et al.: Screening and surveillance for second malignant neoplasms in adult survivors of childhood cancer: a report from the childhood cancer survivor study. Ann Intern Med 153 (7): 442-51, 2010.
36. Casillas J, Castellino SM, Hudson MM, et al.: Impact of insurance type on survivor-focused and general preventive health care utilization in adult survivors of childhood cancer: the Childhood Cancer Survivor Study (CCSS). Cancer 117 (9): 1966-75, 2011.
37. Kirchhoff AC, Lyles CR, Fluchel M, et al.: Limitations in health care access and utilization among long-term survivors of adolescent and young adult cancer. Cancer 118 (23): 5964-72, 2012.
38. Crom DB, Lensing SY, Rai SN, et al.: Marriage, employment, and health insurance in adult survivors of childhood cancer. J Cancer Surviv 1 (3): 237-45, 2007.
39. Pui CH, Cheng C, Leung W, et al.: Extended follow-up of long-term survivors of childhood acute lymphoblastic leukemia. N Engl J Med 349 (7): 640-9, 2003.
40. Oeffinger KC, McCabe MS: Models for delivering survivorship care. J Clin Oncol 24 (32): 5117-24, 2006.
41. Eshelman D, Landier W, Sweeney T, et al.: Facilitating care for childhood cancer survivors: integrating children's oncology group long-term follow-up guidelines and health links in clinical practice. J Pediatr Oncol Nurs 21 (5): 271-80, 2004 Sep-Oct.
42. Castellino S, Muir A, Shah A, et al.: Hepato-biliary late effects in survivors of childhood and adolescent cancer: a report from the Children's Oncology Group. Pediatr Blood Cancer 54 (5): 663-9, 2010.
43. Henderson TO, Amsterdam A, Bhatia S, et al.: Systematic review: surveillance for breast cancer in women treated with chest radiation for childhood, adolescent, or young adult cancer. Ann Intern Med 152 (7): 444-55; W144-54, 2010.
44. Jones DP, Spunt SL, Green D, et al.: Renal late effects in patients treated for cancer in childhood: a report from the Children's Oncology Group. Pediatr Blood Cancer 51 (6): 724-31, 2008.
45. Liles A, Blatt J, Morris D, et al.: Monitoring pulmonary complications in long-term childhood cancer survivors: guidelines for the primary care physician. Cleve Clin J Med 75 (7): 531-9, 2008.
46. Nandagopal R, Laverdière C, Mulrooney D, et al.: Endocrine late effects of childhood cancer therapy: a report from the Children's Oncology Group. Horm Res 69 (2): 65-74, 2008.
47. Nathan PC, Patel SK, Dilley K, et al.: Guidelines for identification of, advocacy for, and intervention in neurocognitive problems in survivors of childhood cancer: a report from the Children's Oncology Group. Arch Pediatr Adolesc Med 161 (8): 798-806, 2007.
48. Ritchey M, Ferrer F, Shearer P, et al.: Late effects on the urinary bladder in patients treated for cancer in childhood: a report from the Children's Oncology Group. Pediatr Blood Cancer 52 (4): 439-46, 2009.
49. Shankar SM, Marina N, Hudson MM, et al.: Monitoring for cardiovascular disease in survivors of childhood cancer: report from the Cardiovascular Disease Task Force of the Children's Oncology Group. Pediatrics 121 (2): e387-96, 2008.
50. Wasilewski-Masker K, Kaste SC, Hudson MM, et al.: Bone mineral density deficits in survivors of childhood cancer: long-term follow-up guidelines and review of the literature. Pediatrics 121 (3): e705-13, 2008.

Subsequent Neoplasms

Subsequent neoplasms (SNs), which may be benign or malignant, are defined as histologically distinct neoplasms developing at least 2 months after completion of treatment for the primary malignancy. Childhood cancer survivors have an increased risk of developing SNs that varies by host factors (e.g., genetics, immune function, hormone status), primary cancer therapy, environmental exposures, and lifestyle factors. The Childhood Cancer Survivor Study (CCSS) reported a 30-year cumulative incidence of 20.5% (95% confidence interval [CI], 19.1%–21.8%) for all SNs, 7.9% (95% CI, 7.2%–8.5%) for SNs with malignant histologies (excluding nonmelanoma skin cancer [NMSC]), 9.1% (95% CI, 8.1%–10.1%) for NMSC, and 3.1% (95% CI, 2.5%–3.8%) for meningioma.[1] This represents a sixfold increased risk of SNs among cancer survivors, compared with the general population.[1] SNs are the leading cause of nonrelapse late mortality (standardized mortality ratio = 15.2; 95% CI, 13.9–16.6).[2] The risk of SNs remains elevated for more than 30 years from diagnosis of the primary cancer. Moreover, prolonged follow-up has established that multiple SNs are common among aging childhood cancer survivors.[3]

The development of an SN is likely multi-factorial in etiology and results from combinations of influences including gene-environment and gene-gene interactions. Outcome following the diagnosis of an SN is variable as treatment for some histological subtypes may be compromised if childhood cancer therapy included cumulative doses of agents and modalities at the threshold of tissue tolerance.[4] The incidence and type of SNs differ with the primary cancer diagnosis, type of therapy received, and presence of genetic conditions. Unique associations with specific therapeutic exposures have resulted in the classification of SNs into the following two distinct groups:

  • Chemotherapy-related myelodysplastic syndrome and acute myeloid leukemia (t-MDS/AML).
  • Radiation-related solid SNs.

Characteristics of t-MDS/AML include a short latency (<10 years from primary cancer diagnosis) and association with alkylating agents and/or topoisomerase II inhibitors.[5,6] Although the long-term risk of subsequent leukemia more than 15 years from primary diagnosis remains significantly elevated (standardized incidence ratio [SIR] = 3.5; 95% CI, 1.9–6.0), these events are relatively rare with an absolute excess risk of 0.02 cases per 1000 person-years.[7] Solid SNs have a strong and well-defined association with radiation and are characterized by a latency that exceeds 10 years.[5] Furthermore, the risk of solid SNs continues to climb with increasing follow-up, whereas the risk of t-MDS/AML plateaus after 10 to 15 years.[8]

Therapy-Related Leukemia

Therapy-related myelodysplastic syndrome and acute myeloid leukemia (t-MDS/AML) has been reported after treatment of Hodgkin lymphoma (HL), acute lymphoblastic leukemia (ALL), and sarcomas, with the cumulative incidence approaching 2% at 15 years after therapy.[8,9,10,11] Some cases of late recurrence among childhood acute lymphoblastic leukemia have been shown to represent cases of new primary leukemia based on TCR gene rearrangement.[12,13] t-MDS/AML is a clonal disorder characterized by distinct chromosomal changes. The following two types are recognized by the World Health Organization classification:[10]

  • Alkylating agent-related type: Alkylating agents associated with t-MDS/AML include cyclophosphamide, ifosfamide, mechlorethamine, melphalan, busulfan, nitrosoureas, chlorambucil, and dacarbazine.[14] The risk of alkylating agent–related t-MDS/AML is dose dependent, with a latency of 3 to 5 years after exposure; it is associated with abnormalities involving chromosomes 5 (-5/del[5q]) and 7 (-7/del[7q]).[14]
  • Topoisomerase II inhibitor-related type: Most of the translocations observed in patients exposed to topoisomerase II inhibitors disrupt a breakpoint cluster region between exons 5 and 11 of the band 11q23 and fuse mixed lineage leukemia with a partner gene.[14] Topoisomerase II inhibitor-related t-AML presents as overt leukemia after a latency of 6 months to 3 years and is associated with balanced translocations involving chromosome bands 11q23 or 21q22.[15]

Therapy-Related Solid Neoplasms

Therapy-related solid SNs represent 80% of all SNs and demonstrate a strong relationship with ionizing radiation. The histological subtypes of solid SNs encompass a neoplastic spectrum ranging from benign and low-grade malignant lesions (e.g., NMSC, meningiomas) to high-grade malignancies (e.g., breast cancers, glioblastomas).[1,11,16,17,18] SN solid tumors in childhood cancer survivors most commonly involve the breast, thyroid, central nervous system (CNS), bones, and soft tissues.[1,8,11,17,19] With more prolonged follow-up of cohorts of adults surviving childhood cancer, epithelial neoplasms involving the gastrointestinal tract and lung have emerged.[1,8,16] Benign and low-grade SNs, including NMSCs and meningiomas, have also been observed with increasing prevalence in survivors treated with radiation for childhood cancer.[1,17,18]

The risk of solid SNs is highest when the exposure occurs at a younger age, increases with the total dose of radiation, and with increasing follow-up after radiation.[1] In recipients of a hematopoietic cell transplant conditioned with high-dose busulfan and cyclophosphamide (Bu-Cy), the cumulative incidence of new solid cancers appears to be similar regardless of exposure to radiation. In a registry-based, retrospective, cohort study, Bu-Cy conditioning without total-body irradiation (TBI) was associated with higher risks of solid SNs compared with the general population. Chronic graft-versus-host disease increased the risk of SN, especially those involving the oral cavity.[20] Some of the well-established radiation-related solid SNs include the following:[5]

  • Skin cancer: NMSCs represent one of the most common SNs among childhood cancer survivors and exhibit a strong association with radiation. Compared to participants who did not receive radiation, CCSS participants treated with radiation had a 6.3-fold increase in risk (95% CI, 3.5–11.3) of reporting a NMSC. Ninety percent of tumors occurred within the radiation field. A CCSS case-control study of the same cohort reported on subsequent basal cell carcinoma. Children who received 35 Gy or more to the skin site had an almost 40-fold excess risk of developing basal cell cancer (odds ratio [OR], 39.8; 95% CI, 8.6–185), compared with those who did not receive radiation; results were consistent with a linear dose-response relationship, with an excess OR per Gy of 1.09 (95% CI, 0.49–2.64).[21] These data underscore the importance of counseling survivors about sun protection behaviors to reduce ultraviolet radiation exposure that may exacerbate this risk.[18] The occurrence of a NMSC as the first SN has been reported to identify a population at high risk for a future invasive malignant SN.[3] CCSS investigators observed a cumulative incidence of a malignant neoplasm of 20.3% (95% CI, 13.0%–27.6%) at 15 years among radiation-exposed survivors who developed NMSC as a first SN compared to 10.7% (95% CI, 7.2%–14.2%) whose first SN was an invasive malignancy.

    Malignant melanoma has also been reported as a SN in childhood cancer survivor cohorts, although at a much lower incidence than NMSCs. A systematic review including data from 19 original studies (total N = 151,575 survivors; median follow-up of 13 years) observed an incidence of 10.8 cases of malignant melanoma per 100,000 childhood cancer survivors per year. Risk factors for malignant melanoma identified among these studies included radiation therapy or the combination of alkylating agents and antimitotic drugs. Melanomas most frequently developed in survivors of Hodgkin lymphoma, hereditary retinoblastoma, soft tissue sarcoma, and gonadal tumors, but the relatively small number of survivors represented in the relevant studies preclude assessment of melanoma risk among other types of childhood cancer.[22]

  • Breast cancer: Breast cancer is the most common therapy-related solid SN after HL, largely because of the high-dose chest radiation used to treat HL (SIR of subsequent breast cancer = 25 to 55).[8,23] Excess risk has been reported in female survivors treated with high-dose, extended-volume radiation at age 30 years or younger.[24] Treatment with higher cumulative doses of alkylating agents and ovarian radiation greater than or equal to 5 Gy (exposures predisposing to premature menopause) have been correlated with reductions in breast cancer risk, underscoring the potential contribution of hormonal stimulation on breast carcinogenesis.[25,26] Emerging data indicate that females treated with low-dose, involved-field radiation also exhibit excess breast cancer risk.[27] For female HL patients treated with chest radiation before age 16 years, the cumulative incidence of breast cancer approaches 20% by age 45 years.[8] The latency period after chest radiation ranges from 8 to 10 years, and the risk of subsequent breast cancer increases in a linear fashion with radiation dose (P for trend < .001).[28] Radiation-induced breast cancer has been reported to have more adverse clinicopathological features compared with breast cancer in age-matched population controls.[29] Although currently available evidence is insufficient to demonstrate a survival benefit from the initiation of breast cancer surveillance in women treated with chest radiation for childhood cancer, interventions to promote detection of small and early-stage tumors may improve prognosis, particularly for those who may have more limited treatment options because of prior exposure to radiation or anthracyclines.
  • Thyroid cancer: Thyroid cancer is observed after neck radiation for HL, ALL, brain tumors, and after TBI for hematopoietic stem cell transplantation.[1,8] The risk of thyroid cancer has been reported to be 18-fold that of the general population.[30] Radiation therapy at a young age is the major risk factor for the development of subsequent thyroid cancers. A linear dose-response relationship between thyroid cancer and radiation is observed up to 29 Gy, with a decline in the OR at higher doses, especially in children younger than 10 years at treatment, demonstrating evidence for a cell kill effect.[31,32] Female gender, younger age at exposure, and longer time since exposure are significant modifiers of the radiation-related risk of thyroid cancer.[32]
  • Brain tumors: Brain tumors develop after cranial radiation for histologically distinct brain tumors [17] or for management of disease among ALL or non-Hodgkin lymphoma patients.[5,33,34] The risk for subsequent brain tumors also demonstrates a linear relationship with radiation dose.[1,17,34] The risk of meningioma after radiation not only increases with radiation dose but also with increased dose of intrathecal methotrexate.[35] Cavernomas have also been reported with considerable frequency after CNS radiation, but have been speculated to result from angiogenic processes as opposed to true tumorigenesis.[36,37]
  • Bone tumors: The risk of subsequent bone tumors has been reported to be 133-fold that of the general population, with an estimated 20-year cumulative risk of 2.8%.[38] Survivors of hereditary retinoblastoma, Ewing sarcoma, and other malignant bone tumors are at a particularly increased risk.[39] Radiation therapy is associated with a linear dose-response relationship.[39,40] After adjustment for radiation therapy, treatment with alkylating agents has also been linked to bone cancer, with the risk increasing with cumulative drug exposure.[39] These data from earlier studies concur with those observed by the CCSS. In this cohort, an increased risk of subsequent sarcoma was associated with radiation therapy (relative risk [RR] = 3.1; 95% CI, 1.5–6.2), a primary diagnosis of sarcoma (RR = 10.1; 95% CI, 4.7–21.8), a history of other SNs (RR = 2.2; 95% CI, 1.1–4.5), and treatment with higher doses of anthracyclines (RR = 2.3; 95% CI, 1.2–4.3) or alkylating agents (RR = 2.2; 95% CI, 1.1–4.6).[41] The 30-year cumulative incidence of subsequent sarcoma in CCSS participants was 1.08% for survivors who received radiation and 0.5% for survivors who did not receive radiation.
  • Sarcomas: Subsequent sarcomas are uncommon SNs and can be of various histologic subtypes, including nonrhabdomyosarcoma soft tissue sarcomas, rhabdomyosarcoma, malignant peripheral nerve sheath tumors, Ewing/primitive neuroectodemal tumors, and other rare types. The CCSS reported on 105 cases and 422 matched controls in a nested case-control study of 14,372 childhood cancer survivors. Sarcomas occurred at a median of 11.8 years (range, 5.3–31.3 years) from original diagnoses. Any exposure to radiation was associated with increased risk (OR, 4.1; 95% CI, 1.8–9.5). A dose-response relationship was observed, with elevated risks at doses between 10 Gy and 29.9 Gy (OR, 15.6; 95% CI, 5.4–53.9), between 30 and 49.9 Gy (OR, 16.0; 95% CI, 3.8–67.8), and higher than 50 Gy (OR, 114.1; 95% CI, 13.5–964.8). Anthracycline exposure was associated with sarcoma risk (OR, 3.5; 95% CI, 1.6–7.7), independent of radiation dose.[42]
  • Lung cancer: Among pediatric childhood cancer survivor cohorts, lung cancer represents a relatively uncommon SN; the 30-year cumulative incidence of lung cancer among CCSS participants was 0.1% (95% CI, 0.0%–0.2%).[1] Lung cancer has been reported after chest irradiation for HL. The risk increases in association with longer elapsed time from diagnosis. Smoking has been linked with the occurrence of lung cancer developing after radiation for HL. The increase in risk of lung cancer with increasing radiation dose is greater among patients who smoke after exposure to radiation than among those who refrain from smoking (P = .04).[43]
  • Gastrointestinal (GI) cancer: There is emerging evidence that childhood cancer survivors develop GI malignancies more frequently and at a younger age than the general population. The Late Effects Study Group reported a 63.9-fold increased risk of gastric cancers and 36.4-fold increased risk of colorectal cancers in adult survivors of childhood HL.[8] In addition to previous radiation therapy, younger age (0–5 years) at the time of the primary cancer therapy significantly increased risk.

    In a French and British cohort-nested, case-control study of childhood solid cancer survivors diagnosed before age 17 years, the risk of developing a SN in the digestive organs varied with therapy. The SNs most often involved the colon/rectum (42%), liver (24%), and stomach (19%). The risk was 9.7-fold higher compared with population controls and exhibited a strong radiation dose-response relationship with an OR of 5.2 (95% CI, 1.7–16.0) for local radiation doses between 10 Gy and 29 Gy and 9.6 (95% CI, 2.6–35.2) for doses of 30 Gy and above, compared with survivors who had not received radiation. Chemotherapy alone and combined-modality therapy were associated with a significantly increased risk of developing a GI SN (SIR = 9.1; 95% CI, 2.3–23.6; SIR = 29.0; 95% CI, 20.5–39.8).[44]

    CCSS investigators reported a 4.6-fold higher risk for GI SNs among their study participants compared with the general population (95% CI, 3.4–6.1). The most prevalent GI SN histology was adenocarcinoma (56%). The SNs most often involved the colon (39%), rectum/anus (16%), liver (18%), and stomach (13%). The highest risk for GI SNs was associated with abdominal radiation (SIR = 11.2; CI, 7.6–16.4), but survivors not exposed to radiation also had a significantly increased risk (SIR = 2.4; CI, 1.4–3.9). High-dose procarbazine (RR = 3.2; CI 1.1–9.4) and platinum drugs (RR = 7.6; CI, 2.3–25.5) independently increased the risk for GI SNs. The SIR for colorectal cancer was 4.2 (CI, 2.8–6.3).[45]

    St. Jude Children's Research Hospital investigators observed that the incidence of a subsequent colorectal carcinoma increased steeply with advancing age, with a 40-year cumulative incidence of 1.4% ± 0.53% among the entire cohort (N = 13,048) and 2.3% ± 0.83% for 5-year survivors. The SIR for subsequent colorectal carcinoma was 10.9 (95% CI, 6.6–17.0) compared with U.S. population controls. Colorectal carcinoma risk increased by 70% with each 10 Gy increase in radiation dose and increasing radiation volume also increased risk. Treatment with alkylating agent chemotherapy was also associated with an 8.8-fold excess risk of subsequent colorectal carcinoma. Collectively, these studies support the need for initiation of colorectal carcinoma surveillance at a young age among survivors receiving high-risk exposures.[46]

Subsequent Neoplasms and Genetic Susceptibility

Literature clearly supports the role of chemotherapy and radiation in the development of SNs. However, interindividual variability exists, suggesting that genetic variation has a role in susceptibility to genotoxic exposures, or that genetic susceptibility syndrome confers an increased risk of cancer, such as Li-Fraumeni syndrome. Previous studies have demonstrated that childhood cancer survivors with either a family history of cancer, but more so, presence of Li-Fraumeni syndrome, carry an increased risk of developing an SN.[47,48] The risk of SNs could potentially be modified by mutations in high-penetrance genes that lead to these serious genetic diseases (e.g., Li-Fraumeni syndrome).[48] However, the attributable risk is expected to be very small because of the extremely low prevalence of mutations in high-penetrance genes. Table 1 below summarizes the spectrum of neoplasms, affected genes, and Mendelian mode of inheritance of selected syndromes of inherited cancer predisposition.

Table 1. Selected Syndromes of Inherited Cancer Predispositiona

SyndromeMajor Tumor TypesAffected GeneMode of Inheritance
WAGR = Wilms tumor, aniridia, genitourinary anomalies, mental retardation.
a Adapted from Strahm et al.[49]
Adenomatous polyposis of the colonColon, hepatoblastoma, intestinal cancers, stomach, thyroid cancerAPCDominant
Ataxia-telangiectasiaLeukemia, lymphomaATMRecessive
Beckwith-Wiedemann syndromeAdrenal carcinoma, hepatoblastoma, rhabdomyosarcoma, Wilms tumorCDKN1C/NSD1Dominant
Bloom syndromeLeukemia, lymphoma, skin cancerBLMRecessive
Fanconi anemiaGynecological tumors, leukemia, squamous cell carcinomaFANCA, FANCB, FANCC, FANCD2, FANCE, FANCF, FANCGRecessive
Juvenile polyposis syndromeGastrointestinal tumorsSMAD4/DPC4Dominant
Li-Fraumeni syndromeAdrenocortical carcinoma, brain tumor, breast carcinoma, leukemia, osteosarcoma, soft tissue sarcomaTP53Dominant
Multiple endocrine neoplasia 1Pancreatic islet cell tumor, parathyroid adenoma, pituitary adenomaMEN1Dominant
Multiple endocrine neoplasia 2Medullary thyroid carcinoma, pheochromocytomaRETDominant
Neurofibromatosis type 1Neurofibroma, optic pathway glioma, peripheral nerve sheath tumorNF1Dominant
Neurofibromatosis type 2Vestibular schwannomaNF2Dominant
Nevoid basal cell carcinoma syndromeBasal cell carcinoma, medulloblastomaPTCHDominant
Peutz-Jeghers syndromeIntestinal cancers, ovarian carcinoma, pancreatic carcinomaSTK11Dominant
RetinoblastomaOsteosarcoma, retinoblastomaRB1Dominant
Tuberous sclerosisHamartoma, renal angiomyolipoma, renal cell carcinomaTSC1/TSC2Dominant
von Hippel-Lindau syndromeHemangioblastoma, pheochromocytoma, renal cell carcinoma, retinal and central nervous tumorsVHLDominant
WAGR syndromeGonadoblastoma, Wilms tumorWT1Dominant
Wilms tumor syndromeWilms tumorWT1Dominant
Xeroderma pigmentosumLeukemia, melanomaXPA, XPB, XPC, XPD, XPE, XPF, XPG, POLHRecessive

Drug-metabolizing enzymes and DNA repair polymorphisms

The interindividual variability in risk of SNs is more likely related to common polymorphisms in low-penetrance genes that regulate the availability of active drug metabolites or are responsible for DNA repair. Gene-environment interactions may magnify subtle functional differences resulting from genetic variations.

Drug-metabolizing enzymes

Metabolism of genotoxic agents occurs in two phases. Phase I involves activation of substrates into highly reactive electrophilic intermediates that can damage DNA, a reaction principally performed by the cytochrome p450 (CYP) family of enzymes. Phase II enzymes (conjugation) function to inactivate genotoxic substrates. The phase II proteins comprise the glutathione S-transferase (GST), NAD(P)H:quinone oxidoreductase-1 (NQO1), and others. The balance between the two sets of enzymes is critical to the cellular response to xenobiotics; for example, high activity of a phase I enzyme and low activity of a phase II enzyme can result in DNA damage.

DNA repair polymorphisms

DNA repair mechanisms protect somatic cells from mutations in tumor suppressor genes and oncogenes that can lead to cancer initiation and progression. An individual's DNA repair capacity appears to be genetically determined.[50] A number of DNA repair genes contain polymorphic variants, resulting in large interindividual variations in DNA repair capacity.[50] Evaluation of the contribution of polymorphisms influencing DNA repair to the risk of SN represents an active area of research.

Screening and Follow-up for Subsequent Neoplasms

Vigilant screening is important for those at risk.[51] Because of the relatively small size of the pediatric cancer survivor population and the prevalence and time to onset of therapy-related complications, undertaking clinical studies to assess the impact of screening recommendations on the morbidity and mortality associated with the late effect is not feasible. However, well-conducted studies on large populations of childhood cancer survivors have provided compelling evidence linking specific therapeutic exposures and late effects. This evidence has been used by several national and international cooperative groups (Scottish Collegiate Guidelines Network, Children's Cancer and Leukaemia Group, Children's Oncology Group [COG]) to develop consensus-based clinical practice guidelines to increase awareness and standardize the immediate care needs of medically vulnerable childhood cancer survivors. The COG Guidelines employ a hybrid approach that is both evidence-based (utilizing established associations between therapeutic exposures and late effects to identify high-risk categories) and grounded in the collective clinical experience of experts (matching the magnitude of the risk with the intensity of the screening recommendations). The screening recommendations in these guidelines represent a statement of consensus from a panel of experts in the late effects of pediatric cancer treatment.[51]

In regard to screening for malignant SNs recommended by the COG Guidelines, certain high-risk populations of childhood cancer survivors merit heightened surveillance due to predisposing host, behavioral, or therapeutic factors.

  • Screening for leukemia: t-MDS/AML usually manifests within 10 years following exposure. Recommendations include monitoring with annual complete blood count for 10 years after exposure to alkylating agents or topoisomerase II inhibitors.
  • Screening after radiation exposure: Most other SNs are associated with radiation exposure. Screening recommendations include careful annual physical examination of the skin and underlying tissues in the radiation field. Specific comments about screening for more common radiation-associated SNs follow:
    • Screening for early-onset skin cancer: Annual dermatological exam should focus on skin lesions and pigmented nevi in the radiation field. Survivors should be counseled about their increased risk of skin cancer, the potential exacerbation of risk through tanning, and the benefits of adhering to behaviors to protect the skin from excessive ultraviolet radiation exposure.
    • Screening for early-onset breast cancer: Since outcome after breast cancer is directly linked to stage at diagnosis, close surveillance resulting in early diagnosis should confer survival advantage.[52] Mammography, the most widely accepted screening tool for breast cancer in the general population, may not be the ideal screening tool by itself for radiation-related breast cancers occurring in relatively young women with dense breasts; hence, the American Cancer Society recommends including adjunct screening with magnetic resonance imaging (MRI).[53] Many clinicians are concerned about potential harms related to radiation exposure associated with annual mammography in these young women. In this regard, it is important to consider that the estimated mean breast dose with contemporary standard two-view screening mammograms is about 3.85 mGy to 4.5 mGy.[54,55,56] Thus, 15 additional surveillance mammograms from age 25 to 39 years would increase the total radiation exposure in a woman treated with 20 Gy of chest radiation to 20.05775 Gy. The benefits of detection of early breast cancer lesions in high-risk women must be balanced by the risk predisposed by a 0.3% additional radiation exposure. To keep young women engaged in breast health surveillance, the COG Guideline recommendations for females who received radiation with potential impact to the breast (i.e., radiation doses of 20 Gy or higher to the mantle, mediastinal, whole lung, and axillary fields) include monthly breast self-examination beginning at puberty; annual clinical breast examinations beginning at puberty until age 25 years; and a clinical breast examination every 6 months, with annual mammograms and MRIs beginning 8 years after radiation or at age 25 years (whichever occurs later).
    • Screening for early-onset colorectal cancer: Screening of those at risk for early-onset colorectal cancer (i.e., radiation doses of 30 Gy or higher to the abdomen, pelvis, or spine) should include colonoscopy every 5 years beginning at age 35 years or 10 years following radiation (whichever occurs later).

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Late Effects of the Cardiovascular System

Radiation, chemotherapy, and biologic agents, both independently and in combination, increase the risk of cardiovascular disease in survivors of childhood cancer; in fact, cardiovascular death has been reported to account for 26% of the excess absolute risk of death by 45 or more years from diagnosis in adults who survived childhood cancers, and is the leading cause of noncancer mortality in select cancers such as Hodgkin lymphoma (HL).[1,2] During the 30 years after cancer treatment, survivors are eight times more likely to die from cardiac causes and 15 times more likely to be diagnosed with congestive heart failure (CHF) than the general population.[3,4] Therapeutic exposures conferring the highest risk are the anthracyclines (doxorubicin, daunorubicin, idarubicin, epirubicin, and mitoxantrone) and thoracic radiation. The risks to the heart are related to cumulative anthracycline dose, method of administration, amount of radiation delivered to different depths of the heart, volume and specific areas of the heart irradiated, total and fractional irradiation dose, age at exposure, latency period, and gender.

Radiation Therapy

The effects of thoracic radiation therapy are difficult to separate from those of anthracyclines because few children undergo thoracic radiation therapy without the use of anthracyclines. However, several reports do allow some segregation of the effects of radiation from those of chemotherapy. Of note, the pathogenesis of injury differs, with radiation primarily affecting the fine vasculature of the heart and anthracyclines directly damaging myocytes.[5,6] Late effects of radiation to the heart include the following:[7,8,9]

  • Delayed pericarditis, which can present abruptly or as a chronic pericardial effusion.
  • Pancarditis, which includes pericardial and myocardial fibrosis, with or without endocardial fibroelastosis.
  • Myopathy (in the absence of significant pericardial disease).
  • Coronary artery disease (CAD), usually involving the left anterior descending artery.
  • Functional valve injury, often aortic.
  • Conduction defects.

These cardiac toxic effects are related to total radiation dose, individual radiation fraction size, and the volume of the heart that is exposed. Modern radiation techniques allow a reduction in the volume of cardiac tissue incidentally exposed to the higher radiation doses. This may translate into a reduced risk for adverse cardiac events.

Anthracycline Therapy

Increased risk of anthracycline-related cardiomyopathy is associated with the following:[10,11,12,13,14,15,16,17,18,19,20,21]

  • Female gender.
  • Cumulative doses greater than 200 mg/m2 to 300 mg/m2.
  • Younger age at time of exposure.
  • Increased time from exposure.

Among these factors, cumulative dose appears to be the most significant in regard to risk of CHF, which develops in less than 5% of survivors after anthracycline exposure of less than 300 mg/m2, approaches 15% at doses between 300 and 500 mg/m2, and exceeds 30% for doses greater than 600 mg/m2.[5,12,22,23]

Schedule of administration of doxorubicin may influence risk of cardiomyopathy. One study looked at the effect of continuous (48 hour) versus bolus (1 hour) infusions of doxorubicin in 121 children who received a cumulative dose of 360 mg/m2 for treatment of acute lymphoblastic leukemia (ALL) and found no difference in the degree or spectrum of cardiotoxicity in the two groups. Because the follow-up time in this study was relatively short, it is not yet clear whether the frequency of progressive cardiomyopathy will differ between the two groups over time.[15] Another study compared cardiac dysfunction in 113 children who received doxorubicin either by single-dose infusion or by a consecutive divided daily-dose schedule. The divided-dose patients received one-third of the total cycle dose over 20 minutes for 3 consecutive days. Patients treated according to a single-dose schedule received the cycle dose as a 20-minute infusion. There was no significant difference in the incidence of cardiac dysfunction between the divided-dose and single-dose infusion groups.[11] Earlier studies in adults have shown decreased cardiotoxicity with prolonged infusion; thus, further evaluation of this question is warranted.[24]

Prevention or amelioration of doxorubicin-induced cardiomyopathy is clearly important because the continued use of doxorubicin is required in cancer therapy. Dexrazoxane is a bisdioxopiperazine compound that readily enters cells and is subsequently hydrolyzed to form a chelating agent. Evidence supports its capacity to mitigate cardiac toxicity in patients treated with doxorubicin.[25,26,27,28,29] Studies suggest that dexrazoxane is safe and does not interfere with chemotherapeutic efficacy.[29] There is a single-study experience suggesting that there could be an increase in malignancies when multiple topoisomerase inhibitors are administered in close proximity; other studies, however, do not show increased risk of malignancies.[29,30,31,32] However, at this time, this should not preclude treatment with dexrazoxane.[33,34]

Two closed Pediatric Oncology Group therapeutic phase III studies for Hodgkin lymphoma (HL) [34,35] measured myocardial toxicity clinically and sequentially over time by echocardiography and electrocardiography, and by determination of levels of cardiac troponin T (cTnT), a protein that is elevated after myocardial damage.[28,36,37,38,39,40] Long-term outcomes for these patients are not yet available.

The angiotensin-converting enzyme inhibitor enalapril has been used in the attempt to ameliorate doxorubicin-induced left ventricular dysfunction. Although a transient improvement in left ventricular function and structure was noted in 18 children, left ventricular wall thinning continued to deteriorate; thus, the intervention with enalapril was not considered successful.[27] For this reason, studies to date in doxorubicin-treated cancer survivors have not demonstrated a benefit of enalapril in preventing progressive cardiac toxicity.[26,27]

A number of studies have examined cardiac function after radiation therapy and doxorubicin exposure using cardiopulmonary exercise stress tests and have found abnormalities in exercise endurance, cardiac output, aerobic capacity, echocardiography during exercise testing, and ectopic rhythms.[41,42,43,44,45] In addition to subclinical abnormalities of systolic function observed by conventional echocardiography, diastolic dysfunction (impaired ventricular relaxation) has also been observed, which may precede impairment of systolic function.[46] Specific abnormalities of cardiac function may progress over time after therapy, as suggested by a report targeting parameters of left ventricular contractility.[47] An increased prevalence of diastolic dysfunction has also been reported in childhood cancer survivors, consistent with the hypothesis of increased vascular and ventricular stiffness associated with precocious cardiovascular aging.[48] It remains unclear whether these abnormalities will have clinical impact. Asymptomatic cardiac toxic effects can be demonstrated in patients who have normal clinical assessments, and abnormalities can be linked to lower self-reported health and New York Heart Association cardiac function scores.[49,50] Clearly, additional studies with long-term follow-up will be necessary to determine optimal screening modalities and frequencies.

Prevalence, Clinical Manifestations, and Risk Factors for Cardiac Toxicity

Children's Cancer Survivors Study (CCSS) investigators detailed dose-response evaluations for both radiation therapy and anthracycline administration to analyze risks (self-reported) of CHF, myocardial infarction (MI), pericardial disease, and valvular abnormalities (see Figure 2).[51]


Four charts showing cumulative incidence of cardiac disorders among childhood cancer survivors by average cardiac radiation dose. First chart shows cumulative incidence (%) of congestive heart failure over time since diagnosis (years) for five levels of radiation: no cardiac radiation, less than 500 cGy cardiac radiation, 500 to less than 1500 cGy cardiac radiation, 1500 to less than 3500 cGy cardiac radiation, and ≥3500 cGy cardiac radiation. The second, third, and fourth charts show incidence over time for myocardial infarction, pericardial disease, and valvular disease, with the same radiation dosage levels.
Figure 2. Cumulative incidence of cardiac disorders among childhood cancer survivors by average cardiac radiation dose. BMJ 2009; 339:b4606. © 2009 by British Medical Journal Publishing Group.

Compared with siblings, survivors of childhood cancer were significantly more likely to report CHF (hazard ratio [HR] = 5.9; 95% confidence interval [CI], 3.4–9.6), MI (HR = 5.0; 95% CI, 2.3–10.4), pericardial disease (HR = 6.3; 95 % CI, 3.3–11.9), or valvular abnormalities (HR = 4.8; 95 % CI, 3.0–7.6). Cardiac radiation exposure of 15 Gy or more increased the risk of CHF, MI, pericardial disease, and valvular abnormalities by twofold to sixfold compared with nonirradiated survivors.[51] There was no evidence for increased risk following doses less than 5 Gy, and slight elevations in risk were not statistically significant following doses between 5 to 15 Gy. Exposure to 250 mg/m2 or more of anthracyclines also increased the risk of CHF, pericardial disease, and valvular abnormalities by two to five times compared with survivors who had not been exposed to anthracyclines. The cumulative incidence of adverse cardiac outcomes in childhood cancer survivors continued to increase up to 30 years after diagnosis and ranged from about 2% to slightly over 4% overall, but to much higher cumulative percentages for those receiving the highest cardiac radiation doses and the highest cumulative dose of anthracyclines.[51]

A study of 4,122 5-year survivors of childhood cancer diagnosed before 1986 in France and the United Kingdom also provides evidence for an association between radiation dose and risk of cardiovascular disease.[52] After 86,453 person-years of follow-up (average, 27 years), 603 deaths had occurred. The overall standardized mortality ratio was 8.3-fold (95% CI, 7.6–9.0) higher in relation to the general populations in France and the United Kingdom. Thirty-two patients had died of cardiovascular diseases, which is fivefold (95% CI, 3.3–6.7) more than expected. The risk of dying of cardiac diseases (n = 21) was significantly higher in individuals who had received a cumulative dose of anthracyclines greater than 360 mg/m2 (relative risk [RR] = 4.4; 95% CI, 1.3–15.3) and following an average radiation dose exceeding 5 Gy (RR = 12.5 for 5–14.9 Gy and RR = 25.1 for >15 Gy) to the heart. A linear relationship was found between the average dose of radiation to the heart and the risk of cardiac mortality (excess RR at 1 Gy, 60%).

Subclinical cardiac function was evaluated by a group from the Netherlands. Of 601 eligible adult 5-year childhood cancer survivors, 525 (87%) had an echocardiogram performed, of which 514 were evaluable for assessment of the left ventricular shortening fraction (LVSF).[20] The median overall LVSF in the whole group of childhood cancer survivors was 33.1% (range, 13.0%–56.0%). Subclinical cardiac dysfunction (LVSF <30%) was identified in 139 patients (27%). In a multivariate linear regression model, LVSF was reduced with younger age at diagnosis, higher cumulative anthracycline dose, and radiation to the thorax. High-dose cyclophosphamide and ifosfamide were not associated with a reduction of LVSF.

Cardiovascular Disease in Select Cancer Subgroups

Hodgkin lymphoma

Hodgkin lymphoma (HL) continues to be the pediatric malignancy associated with the greatest risk of cardiovascular disease, with a 13.1 excess absolute risk per 10,000 person years for cardiovascular death.[53] Newer treatment approaches are specifically designed to reduce exposure to cardiotoxic agents (e.g., total anthracycline dose) and radiation dose and volume. Moreover, newer trials explore the safe elimination of radiation from primary therapy.

Data from the German-Austrian DAL-HD studies show a dose response for cardiac diseases in children treated for HL with combined radiation and anthracycline-based chemotherapy (cumulative doxorubicin dose was uniformly 160 mg/m2). The 25-year cumulative incidence of cardiac diseases was 3% with no radiation therapy, 5% after 20 Gy, 6% after 25 Gy, 10% after 30 Gy, and 21% after 36 Gy.[54] An older study of 635 patients treated for childhood HL confirms the risks that occur after higher-dose radiation therapy. The actuarial risk of pericarditis requiring pericardiectomy was 4% at 17 years posttreatment (occurring only in children treated with higher radiation doses). Only 12 patients died of cardiac disease, including seven deaths from acute MI; however, these deaths occurred only in children treated with 42 Gy to 45 Gy.[55] In an analysis of 48 asymptomatic patients treated for HL from 1970 to 1991 with mediastinal therapy (median dose 40 Gy) and screened for the presence of subclinical cardiac abnormalities, 43% had unsuspected valvular abnormalities, 75% had a conduction abnormality or arrhythmia, and 30% had reduced VO2 during exercise tests. These abnormalities were noted at a mean of 15.5 years posttherapy suggesting that survivors of HL treated with high doses of mediastinal radiation therapy require long-term cardiology follow-up.[25] Among children treated with 15 Gy to 26 Gy, none developed radiation-associated cardiac problems.[55]

The risk of delayed valvular and CAD after lower radiation doses requires additional study of patients followed for longer periods of time to definitively ascertain lifetime risk. Nontherapeutic risk factors for CAD—such as family history, obesity, hypertension, smoking, diabetes, and hypercholesterolemia—are likely to impact the frequency of disease.[7,8,56]

Other malignancies

Brain tumor: A study of self-reported late effects among 1,607 survivors of childhood brain tumors [57] showed that 18% of survivors reported a heart or circulatory late effect. Risk was highest among those treated with surgery, radiation therapy, and chemotherapy compared with surgery and radiation therapy alone, suggesting a potential additive vascular injury from chemotherapy. Children who receive spinal radiation for treatment of central nervous system tumors have been demonstrated to show low maximal cardiac index on exercise testing and pathologic Q-waves in inferior leads on ECG testing, and higher posterior-wall stress.[58]

Acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML): In a study of ALL survivors reporting a chronic medical condition in the CCSS cohort, the risk of a cardiac condition was nearly sevenfold higher compared with the siblings. No significant association was identified based on radiation exposure. A similar analysis among AML survivors in the cohort found the 20-year cumulative incidence of cardiac disease to be 4.7%. It is noteworthy that adult survivors of childhood ALL have an increased prevalence of obesity and insulin resistance and may be at risk for developing diabetes, dyslipidemia, and metabolic syndrome, all known to be potent risk factors for premature cardiovascular disease.[59]

Wilms tumor: A long-term follow-up study of Wilms tumor survivors reported a cumulative risk of CHF of 4.4% at 20 years for those who received doxorubicin as part of their initial therapy and 17.4% at 20 years when doxorubicin was received as part of therapy for relapsed disease. Risk factors for CHF in this cohort included female gender, lung irradiation with doses 20 Gy or higher, left-sided abdominal irradiation, and doxorubicin dosage of 300 mg/m2 or more.[10]

Hematopoietic cell transplantation (HCT): Cardiac complications after bone marrow transplantation may occur, with arrhythmia, pericarditis, and cardiomyopathy predominating, although many are either acute or subacute effects. High-dose cyclophosphamide clearly is a causative agent; total-body irradiation is a secondary contributing factor.[41,56,60] In a report from the Bone Marrow Transplant Survivors Study that compared 145 HCT survivors, 7,207 conventionally treated survivors, and 4,020 siblings from the CCSS cohort,[61] median time from HCT to study participation was 11.0 years (range, 2.3–25.9 years). The prevalence of cardiovascular conditions (grades 3–5) was 4.8% in HCT survivors, versus 3.2% in conventionally treated CCSS survivors, and it was 0.5% (for grades 3–4) in the sibling control CCSS cohort. The RR was 0.5 (95% CI, 0.1–2.5) for the conventionally treated survivors versus HCT survivors, and 12.7 (95% CI, 5.4–30.0) for the HCT survivors versus siblings.

Vascular Disease/Cerebrovascular Accident

A spectrum of vascular morbidities may occur after radiation therapy used to treat malignancies such as lymphomas, head and neck cancers, and brain tumors. Specifically, carotid artery and cerebrovascular injury occur after cervical and central nervous system irradiation. French investigators observed a significant association with radiation dose to the brain and long-term cerebrovascular mortality among 4,227 five-year childhood cancer survivors (median follow-up, 29 years). Survivors who received more than 50 Gy to the prepontine cistern had an HR of 17.8 (95% CI, 4.4–73) of death from cerebrovascular disease compared with those who had not received radiation therapy or who had received less than 0.1 Gy in the prepontine cistern region.[62] The RR for cerebrovascular accident (CVA [stroke]) in the CCSS cohort was almost tenfold higher compared with the sibling control group;[4] notably, risks were highest among the adult survivors of childhood ALL, brain tumors, and HL.[63,64] Leukemia survivors were six times more likely to suffer a CVA compared with their siblings, whereas brain tumor survivors were 29 times more likely to suffer a CVA. Of the brain tumor cohort, 69 of 1,411 patients who had a history of radiation therapy reported a CVA (4.9%), with a cumulative incidence of 6.9% (95% CI, 4.47–9.33) at 25 years. Survivors exposed to cranial radiation therapy greater than 30 Gy had an increased risk for CVA, with the highest risk among those treated with greater than 50 Gy.[64] Adult survivors of childhood HL who were treated with thoracic radiation therapy, including mediastinal and neck, had a 5.6-fold increased risk for CVA than their siblings (median dose 40 Gy).[63] In another study from the Netherlands of 2,201 5-year survivors of HL (of whom 547 were younger than 21 years), and with median follow-up of 17.5 years, 96 patients developed cerebrovascular disease (55 CVA, 31 transient ischemic attacks [TIA], and 10 both CVA and TIA), with a median age at diagnosis of 52 years.[65] Most ischemic events were from large-artery atherosclerosis (36%) or cardioembolism (24%). The standardized incidence ratio (SIR) for CVA was 2.2, and for TIA it was 3.1. The cumulative incidence of ischemic CVA or TIA 30 years after HL treatment was 7%. For patients younger than 21 years, the SIR for CVA was 3.8, and for TIA it was 7.6. Radiation to the neck and mediastinum was an independent risk factor for ischemic cerebrovascular disease (HR = 2.5; 95% CI, 1.1–5.6) versus without radiation therapy. Treatment with chemotherapy was not associated with increased risk. It is noteworthy that hypertension, diabetes mellitus, and hypercholesterolemia were associated with the occurrence of ischemic cerebrovascular disease, whereas smoking and overweight were not. [65]

Table 2. Cardiovascular Late Effects

Predisposing TherapyPotential Cardiovascular EffectsHealth Screening
DOE = dyspnea on exertion; SOB = shortness of breath.
Anthracyclines (daunorubicin, doxorubicin, idarubicin, epirubicin); mitoxantroneCardiomyopathy; arrhythmias; subclinical left ventricular dysfunctionHistory: SOB, DOE, orthopnea, chest pain, palpitations
Cardiovascular exam
Echocardiogram or other modality to evaluate left ventricular systolic function
Electrocardiogram
Laboratory: lipid profile, consider troponin or brain natriuretic peptide (BNP) level
Radiation impacting the heartCongestive heart failure; cardiomyopathy; pericarditis/pericardial fibrosis; valvular disease; atherosclerotic heart disease/myocardial infarction; arrhythmiaHistory: SOB, DOE, orthopnea, chest pain, palpitations
Cardiovascular exam: signs of heart failure, arrhythmia, valve dysfunction
Echocardiogram or other modality to evaluate left ventricular systolic function
Electrocardiogram
Laboratory: lipid profile
Radiation impacting vascular structuresCarotid or subclavian artery diseaseHistory: transient/permanent neurological events
Blood pressure
Cardiovascular exam: peripheral pulses, presence of bruits
Neurological exam
Carotid ultrasound
Laboratory: lipid profile
Plant alkaloids (vinblastine, vincristine)Vasospastic attacks (Raynaud's phenomena); autonomic dysfunction (e.g., monotonous pulse)History: vasospasms of hands, feet, nose, lips, cheeks, or earlobes related to stress or cold temperatures
Exam of affected area
Electrocardiogram
Platinum agents (cisplatin, carboplatin)DyslipidemiaFasting lipid profile

In general, survivors should be counseled regarding the cardiovascular benefits of maintaining healthy weight, adhering to a heart-healthy diet, participating in regular physical activity, and abstaining from smoking. Survivors should obtain medical clearance before engaging in extreme exercise programs. Clinicians should consider baseline and follow-up screening as needed for comorbid conditions that impact cardiovascular health.

Refer to the Children's Oncology Group Long-Term Follow-Up Guidelines for Survivors of Childhood, Adolescent, and Young Adult Cancers for cardiovascular late effects information including risk factors, evaluation, and health counseling.

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Late Effects of the Central Nervous System

Neurocognitive

Neurocognitive late effects most commonly follow treatment of malignancies that require central nervous system (CNS)-directed therapies, such as cranial radiation, systemic therapy with high-dose methotrexate or cytarabine, or with intrathecal chemotherapy. Children with brain tumors or acute lymphoblastic leukemia are most likely to be affected. Risk factors for the development of neurocognitive side effects are female gender, young age at the time of treatment, higher radiation dose, and treatment with both cranial radiation and chemotherapy (systemic or intrathecal).[1,2,3,4]

Brain tumors

Survival rates have increased over recent decades for children with brain tumors; however, long-term cognitive effects due to their illness and associated treatments are emerging. In childhood and adolescent brain tumor survivors, tumor site, treatment of hydrocephalus with a shunt, paralysis, auditory difficulties, or history of a stroke have emerged as risk factors for adverse neurocognitive effects.[5,6]

Cranial radiation therapy has been associated with the highest risk of long-term cognitive morbidity particularly in younger children.[7] There is an established dose-response relationship with those getting higher-dose cranial radiation therapy consistently performing more poorly on intellectual measures. The negative impact of radiation treatment has been characterized by changes in intelligence quotient (IQ) scores, which have been noted to drop about 2 to 5 years after diagnosis and an attenuation of the decline 5 to 10 years afterward, followed by stabilization of the IQ scores 20 to 40 years after diagnosis.[8,9,10] The decline over time is typically reflective of the child's failure to acquire new abilities or information at a rate similar to peers, rather than a progressive loss of skills and knowledge.[5] Affected children may experience information-processing deficits resulting in academic difficulties, and are prone to problems with receptive and expressive language, attention span, and visual and perceptual motor skills.[9,11,12] These changes in intellectual functioning may be partially explained by radiation-induced or chemotherapy-induced reduction of normal white matter volume as evaluated through magnetic resonance imaging (MRI).[13] Using lower doses of radiation and more targeted volumes have demonstrated improved results in neurocognitive effects of therapy.[14] In this regard, a report from St. Jude Children's Research Hospital showed cognitive decline after conformal radiation therapy in 78 children younger than 20 years (mean, 9.7 years) with low-grade glioma treated with 54 Gy (see Figure 3). In fact, age at time of irradiation was more important than radiation dose in predicting cognitive decline. Children younger than 5 years showed the most cognitive decline.[15]


Graph shows modeled IQ scores after conformal radiation therapy, by age measured in years, and time measured in months, after the start of CRT for pediatric low-grade glioma.
Figure 3. Modeled intelligence quotient (IQ) scores after conformal radiation therapy (CRT) by age for pediatric low-grade glioma. Age is measured in years, and time is measured in months after the start of CRT. Thomas E. Merchant, Heather M. Conklin, Shengjie Wu, Robert H. Lustig, and Xiaoping Xiong, Late Effects of Conformal Radiation Therapy for Pediatric Patients With Low-Grade Glioma: Prospective Evaluation of Cognitive, Endocrine, and Hearing Deficits, Journal of Clinical Oncology, volume 27, issue 22, pages 3691-3697. Reprinted with permission. © (2009) American Society of Clinical Oncology. All rights reserved.

Glutathione S-transferase M1 and T1 gene polymorphisms may predict patients with medulloblastoma who are more likely to experience neurocognitive toxicity secondary to radiation.[16]

Acute lymphoblastic leukemia (ALL)

One of the great medical success stories of the past generation is how advances in the treatment of ALL have dramatically improved survival. With the recognition that CNS relapse was common among children in bone marrow remission, presymptomatic CNS radiation and intrathecal chemotherapy were introduced into the treatment of children with ALL in the 1960s and 1970s. The increase in cure rates for children with ALL over the past decades has resulted in greater attention to the neurocognitive morbidity and quality of life of survivors. The goal of current ALL treatment is to minimize adverse late effects while maintaining high survival rates. Patients are stratified for treatment according to their risk of relapse. Cranial radiation is reserved for children (less than 20%) considered at high risk for CNS relapse.[17]

Although low-, standard- and most high-risk patients currently are treated with chemotherapy-only protocols, the described neurocognitive effects for ALL patients are based on a heterogeneous treatment group of survivors in the past who were treated with combinations (simultaneously or sequentially) of intrathecal chemotherapy, radiation, and high-dose chemotherapy making it difficult to differentiate the impact of the individual components. In the future, more accurate data will be available as to the neurocognitive effects on survivors of childhood ALL treated with chemotherapy only.

In a large prospective study (N = 555) of neurocognitive outcomes in children with newly diagnosed ALL randomly assigned to CNS-directed therapy according to risk group (low: intrathecal methotrexate vs. high-dose methotrexate; high: high-dose methotrexate vs. cranial radiation therapy), a significant reduction in IQ scores (4 to 7 points) was observed between all patient groups when compared with controls (P < .002), regardless of the CNS treatment delivered. Children younger than 5 years were more likely to have IQs below 80 at 3 years compared with children older than 5 years at diagnosis, irrespective of treatment allocation, suggesting that younger children are more vulnerable to treatment-related neurologic toxic effects.[18]

ALL and cranial radiation

In survivors of ALL, cranial radiation therapy does lead to identifiable neurodevelopment late sequelae. Although these abnormalities are mild in some patients (overall IQ fall of approximately 10 points), those who have received higher doses at a young age may have significant learning difficulties.[19,20] Deficits in neuropsychological functions, such as visual-motor integration, processing speed, attention, and short-term memory are reported in children treated with 1800 cGy to 2400 cGy.[21,22] Girls and younger children are more vulnerable to cranial irradiation.[23,24,25] The decline in intellectual functioning appears to be progressive, showing more impairment of cognitive function with increasing time since radiation therapy.[26] When the neurocognitive outcome of radiation therapy and chemotherapy-only CNS regimens are directly compared, the evidence suggests a better outcome for those treated with chemotherapy alone although some studies show no significant difference.[27,28,29]

It should be noted that the phenotype of attention problems in ALL survivors appears to differ from developmental attention-deficit disorder, as few survivors demonstrate significant hyperactivity/impulsivity. By contrast, impairments in cognitive efficiency (information processing and short-term memory) and executive functioning (organization and planning) have been more often observed among ALL survivors treated with cranial radiation therapy, and have been observed in children at lower frequency among those treated with chemotherapy alone.[30]

ALL and chemotherapy–only CNS therapy

Most studies of chemotherapy-only CNS-directed treatment display good neurocognitive long-term outcomes. However, one review suggests modest effects on processes of attention, speed of information processing, memory, verbal comprehension, visual-spatial skills, and visual-motor functioning; global intellectual function was found to be preserved.[21,27,31,32,33] Few longitudinal studies evaluating long-term neurocognitive outcome report adequate data for a decline in global IQ after treatment with chemotherapy alone.[32,34] The academic achievement of ALL survivors in the long term seems to be generally average for reading and spelling with deficits mainly affecting arithmetic performance.[27,35,36] Further risk factors for poor neurocognitive outcome after chemotherapy-only CNS-directed treatment are younger age and female gender.[34,37] Time since diagnosis or treatment does not appear to have a similar influence on neurocognitive functioning as observed following cranial irradiation.

Because of its penetrance into the CNS, systemic methotrexate has been used in a variety of low-dose and high-dose regimens for leukemia CNS prophylaxis. Systemic methotrexate in high doses and combined with radiation therapy can lead to an infrequent but well-described leukoencephalopathy, in which severe neurocognitive deficits are obvious.[38]

Other factors

The type of steroid used for ALL systemic treatment does not affect cognitive functioning. This is based on long-term neurocognitive testing in 92 children with a history of standard-risk ALL who had received either dexamethasone or prednisone during treatment that observed no meaningful differences in cognitive functioning based on corticosteroid randomization.[39]

Treatment intensity and duration can also adversely affect cognitive performance, because of absences from school and interruption of studies. In the Childhood Cancer Survivor Study (CCSS), treatment-related neurocognitive impairment resulted in decreased educational attainment and greater utilization of special education services. Those ALL survivors who were provided with special educational services had comparable educational attainment to siblings, whereas those not reporting use of special education had lower educational attainment.[40]

Infants with ALL

Infants with ALL are considered to be at high risk for CNS disease. In the past, infants diagnosed before age 2 years were treated with cranial irradiation. As a result, significant deficits in overall intellectual function were noted as compared with cancer controls.[41] Currently, most ALL treatment protocols do not specify cranial irradiation for infants or very young children. When cranial radiation is avoided, neurodevelopmental outcome improves. One long-term study of infants who received high-dose systemic methotrexate combined with intrathecal cytarabine and methotrexate for CNS leukemia prophylaxis and were tested 3 to 9 years posttreatment showed cognitive function was in the average range.[42]

Other cancers

Neurocognitive abnormalities have been reported in other groups of cancer survivors besides patients with CNS tumors and ALL. In a study of adult survivors of childhood non-CNS cancers (including ALL, n = 5,937), 13% to 21% of survivors had impairment in task efficiency, organization, memory, or emotional regulation. This rate of impairment was approximately 50% higher than that in the sibling comparison. Factors such as diagnosis before age 6 years, female gender, cranial radiation therapy, and hearing impediment were associated with impairment.[22]

Stem cell transplantation

Cognitive and academic consequences of stem cell transplantation in children have also been evaluated. In a report from the St. Jude Children's Research Hospital in which 268 patients were treated with stem cell transplant, minimal risk of late cognitive and academic sequelae was seen. Subgroups of patients were at relatively higher risk, including those undergoing unrelated donor transplantation, receiving total-body irradiation, and developing graft-versus-host disease (GVHD). However, these differences were small relative to differences in premorbid functioning, particularly those associated with socioeconomic status.[43]

Neurocognitive function of pediatric patients with hematologic malignancies who had undergone hematopoietic stem cell transplantation (HSCT) was evaluated prior to HSCT and then at 1, 3, and 5 years post-HSCT. In this series of 38 patients who had all received intrathecal chemotherapy as part of their treatment, significant declines in visual motor skills and memory test scores were noted within the first year posttransplant. By 3 years posttransplant, there was an improvement in the visual motor development scores and memory scores, but there were new deficits seen in long-term memory scores. By 5 years posttransplant, there were progressive declines in verbal skills, performance skills, and new deficits seen in long-term verbal memory scores. The greatest decline in neurocognitive function occurred in patients who received cranial irradiation either as part of their initial therapy or as part of their HSCT conditioning.[44]

Most neurocognitive late effects are thought to be related to white matter damage in the brain. This was investigated in children with leukemia who were treated with HSCT. In a series of 36 patients, performance on neurocognitive measures associated with white matter was compared with performance on measures associated with gray matter. Composite white matter scores were significantly lower than composite gray matter scores.[45]

Neurologic Sequelae

Neurologic complications may be predisposed by tumor location, neurosurgery, radiation therapy, or specific neurotoxic chemotherapeutic agents. In children with CNS tumors, mass effect, tumor infiltration, and increased intracranial pressure may result in motor or sensory deficits, cerebellar dysfunction, and such secondary effects as seizures and cerebrovascular complications.

Clinical or radiographic leukoencephalopathy has been reported after cranial irradiation and high-dose systemic methotrexate administration. Younger patients and those given radiation doses greater than 24 Gy are more vulnerable to this complication. White matter changes may be accompanied by such neuroimaging abnormalities as dystrophic calcifications, cerebral lacunae, and cerebral atrophy.

Vinca alkaloid agents (vincristine and vinblastine) and cisplatin may cause peripheral neuropathy. This condition presents during treatment and appears to clinically resolve after completion of therapy. However, higher cumulative doses of vincristine and/or intrathecal methotrexate have been linked to neuromuscular impairments in long-term survivors of childhood ALL, which suggests that persistent effects of these agents may impact functional status in aging survivors.[46]

In a report from the CCSS that compared 4,151 adult survivors of childhood ALL with their siblings, survivors were at an elevated risk for late-onset coordination problems, motor problems, seizures, and headaches. The overall cumulative incidence was 44% at 20 years. Serious headaches were most common, with a cumulative incidence of 25.8% at 20 years followed by focal neurologic dysfunction (21.2%) and seizures (7%). Children who were treated with regimens that included cranial radiation for ALL and those who suffer relapse were at increased risk for late-onset neurologic sequelae.[47]

Table 3. Central Nervous System Late Effects

Predisposing TherapyNeurologic EffectsHealth