Susan A. Smith

Background: Long-term survivors of pediatric Hodgkin lymphoma are at risk of late treatment-related mortality, cancer, and heart disease. Although modified treatments have reduced radiation exposure, long-term risks in late adulthood are unknown. Methods: Using a simulation model based on data from the Childhood Cancer Survivor Study and national databases, we projected overall survival and cumulative incidence of breast cancer and heart failure for 5-year survivors treated with extended-field radiation therapy (RT), chest RT at doses of 35 Gy or higher, chest RT at doses below 35 Gy, or chemotherapy only. Estimates were compared with general-population individuals who faced only age-related risks. We report the mean and 95% uncertainty intervals (UIs) among 1000 iterations. Results: At 65 years of age, projected overall survival ranged from 24.7% (95% UI = 17.7-32.5) after extended-field RT to 71.8% (95% UI = 44.9-81.8) after chemotherapy only compared with 86.4% (95% UI = 83.8-88.8) in the general population. Cumulative breast cancer incidence among female survivors was 61.1% for extended-field RT, 59.7% for chest RT at doses of 35 Gy or higher, 49.8% for chest RT at doses below 35 Gy, and 17.9% for chemotherapy only vs 6.1% in the general population. Heart failure risks among all survivors were 34.8%, 33.4%, 28.4%, and 16.0, respectively, vs 4.3% for the general population. Across all subgroups, breast cancer and heart failure were projected to occur 16.1 to 31.7 and 21.0 to 25.9 years earlier, respectively, relative to general-population risks at 65 years of age. Conclusions: Although historical reductions in RT dose and field have substantially improved long-term survival, survivors treated with lower-dose RT or chemotherapy alone remain at markedly elevated risk for early-onset breast cancer and heart failure.

Background: Radiotherapy increases contralateral breast cancer risk, while hormone therapy reduces it; their combined effects are unclear. Methods: Data from two US retrospective cohort studies of 5-year breast cancer survivors (stage I-III, ages 20–84), Kaiser Permanente (KP, 1990–2012) and SEER (1990–2013), were analysed. Contralateral breast radiation doses were estimated for the KP cohort. Multivariable Poisson regression estimated relative risks (RRs) and excess relative risks per Gray (ERR/Gy), stratified by hormone therapy use. Results: KP cohort ( n = 9053) included 353 contralateral breast cancer cases (73% ER+); SEER cohort ( n = 244,834) included 10,470 cases (72% ER+). Among women with ER+ first breast cancer, radiotherapy increased the risk of ER+ contralateral breast cancer in non-users of hormone therapy (KP RR = 2.2, 95%CI:1.20–4.14; SEER RR = 1.12, 1.04–1.21), but not in users (KP RR = 0.88, 0.61–1.26; SEER RR = 1.03, 0.94–1.12). In KP, higher radiation dose increased risk of ER+ contralateral breast cancer among non-users (ERR/Gy=1.39, 95%CI:0.33,3.66), but not among users (ERR/Gy= –0.13, –0.36,0.23). Radiotherapy also increased risk of ER– contralateral breast cancer (KP RR = 1.85, 95%CI: 0.95–3.59; SEER RR = 1.12, 1.01–1.23), especially in younger exposed women (SEER RR = 1.31, 1.02-1.69 for age <40 vs 40+ years). Additionally, the risk increased linearly with radiation dose to the contralateral breast (ERR/Gy=0.87, 0.04,2.72). Conclusions: Radiotherapy increased contralateral breast cancer risk, but hormone therapy appeared to mitigate this risk for ER+ cases. These findings have important implications for individuals exposed to chest radiation.

PURPOSE: Among childhood cancer survivors, we evaluated not previously explored relationships between colorectal subsequent malignant neoplasm (SMN) incidence and colorectum-specific radiation dose metrics currently used in radiation therapy (RT) planning and expanded upon previously reported chemotherapy associations. METHODS: The Childhood Cancer Survivor Study (CCSS) includes 5-year survivors of childhood cancer diagnosed between 1970 and 1999. RT was assessed as mean colorectal dose (MCD) and the percent volume (V _{X Gy} ) receiving ≥5, 10, 20, 30, and 40 Gy. Chemotherapy was assessed as cumulative doses for procarbazine and platinum agents, cyclophosphamide-equivalent doses for alkylating agents, and doxorubicin-equivalent doses for anthracyclines. Piecewise-exponential models and excess rate ratio (ERR) models evaluated dose-response relationships for the incidence of colorectal SMNs. Reference groups were those not receiving the assessed treatment(s). RESULTS: Among 25,723 survivors (median follow-up = 28.5 years; range = 5.0-48.9), 104 colorectal SMNs were identified. A dose-response relationship was observed between MCD and colorectal SMN rates; incidence rate ratios (IRRs) for 10 to 20 Gy IRRs were 3.8 (95% CI, 1.9 to 7.6), 4.9 (95% CI, 2.0 to 12.0), and 8.7 (95% CI, 3.5 to 21.6) for irradiated volumes of 20% to 2 , 3.7 (95% CI, 2.2 to 6.4) for cyclophosphamide-equivalent dose ≥6,000 mg/m ² , and 4.5 (95% CI, 2.0 to 10.1) for platinum dose ≥450 mg/m ² . For procarbazine dose, the IRR was 6.3 (95% CI, 3.0 to 13.2) for 4,200 to 2 and 9.0 (95% CI, 4.3 to 18.9) for ≥7,036 mg/m ² . In the absence of RT, colorectal SMN rates increased with exposure to any platinum-based agent (IRR, 3.8 [95% CI, 1.1 to 12.7]), alkylator (IRR, 4.8 [95% CI, 1.6 to 14.4]), or procarbazine (IRR, 16.9 [95% CI, 5.9 to 48.8]). Colorectal SMN rates increased linearly with procarbazine dose (ERR per 1,000 mg/m ² = 73.0 [95% CI, 26.4% to 119.6%]) and MCD (ERR per 1 Gy = 20.8 [95% CI, 9.0% to 32.5%]). Quadratic ERR models did not improve data fit compared with linear ERR models. CONCLUSION: These RT and chemotherapy dose-response relationships can better inform contemporary RT planning for pediatric patients and surveillance guidelines for high-risk survivors.

PURPOSE: Melanoma as a subsequent malignant neoplasm has been described among childhood cancer survivors; however, the risk factors and long-term survival are not well understood. METHODS: We assessed incidence, risk factors, and outcomes for melanoma among participants in the Childhood Cancer Survivor Study cohort. Cumulative incidence and standardized incidence ratios (SIRs) were calculated, and multivariable Cox models were used to determine hazard ratios (HRs) and associated 95% CI for melanoma risk factors. Radiation exposure to seven body regions and melanoma status for each of eight regions per survivor were integrated into the Cox model. RESULTS: Among 25,716 participants, 177 melanomas developed in 160 survivors (110 invasive, 62 in situ cutaneous, five ocular). The 40-year melanoma cumulative incidence was 1.1% (95% CI, 0.9 to 1.4) for all participants and 1.5% (95% CI, 1.0 to 2.1) among those receiving a cumulative radiation dose of ≥40 Gy. Compared with the general population, the SIR for invasive skin or ocular melanoma was 2.0 (95% CI, 1.6 to 2.4). A cumulative radiation dose of ≥40 Gy to the corresponding body region(s) of the melanoma (HR, 2.0 [95% CI, 1.1 to 3.7]), a cumulative cyclophosphamide equivalent dose of ≥20,000 mg/m ² (HR, 1.9 [95% CI, 1.1 to 3.6]), and bleomycin exposure (HR, 2.2 [95% CI, 1.2 to 4.1]) were associated with increased cutaneous melanoma. Invasive melanoma at any site was associated with an increased risk of death (HR, 2.4 [95% CI, 1.7 to 3.3]). CONCLUSION: Childhood cancer survivors have more than a two-fold increased risk of melanoma compared with the general population, and those with an invasive melanoma have more than a two-fold risk of death. High-dose radiation and alkylating agent exposure, and bleomycin are important risk factors for melanoma and should be considered in future patient guidance and screening.

Background: It is not known whether temporal changes in childhood cancer therapy have reduced risk of subsequent malignant neoplasms of the central nervous system (CNS), a frequently fatal late effect of cancer therapy. Methods: Five-year survivors of primary childhood cancers diagnosed between 1970 and 1999 in the Childhood Cancer Survivor Study with CNS subsequent malignant neoplasms were identified. Cumulative incidence rates and standardized incidence ratios were compared among survivors diagnosed between 1970-1979 (n = 6223), 1980-1989 (n = 9680), and 1990-1999 (n = 8999). Multivariable models assessed risk factors for CNS subsequent malignant neoplasms. Results: A total of 157 CNS subsequent malignant neoplasms (1970s, 52; 1980s, 63; 1990s, 42) were identified, excluding meningiomas, which were most often malignant gliomas. The proportion of survivors receiving any cranial radiotherapy exposure was reduced over time (1970s, 77.0%; 1980s, 54.3%; 1990s, 33.9%), while the proportion receiving more than 35 Gy cranial radiotherapy showed a smaller reduction (11.4%, 10.8%, and 8.5%, respectively). Twenty-year cumulative incidence and standardized incidence ratios for CNS subsequent malignant neoplasms by treatment decade were 0.32% (95% confidence interval = 0.18% to 0.46%) and 6.6 (95% CI = 5.0 to 8.7); 0.55% (95% CI = 0.41% to 0.70%) and 8.3 (95% CI = 6.6 to 10.4); and 0.43% (95% CI = 0.31% to 0.55%) and 9.2 (95% CI = 7.0 to 12.0), respectively, with no statistically significant decreases between eras. Multivariable analyses showed increased risk for cranial radiotherapy dose levels more than 10 Gy and for primary diagnoses of medulloblastoma and/or primitive neuro-ectodermal tumor (hazard ratio [HR] = 18.7, 95% CI = 9.2 to 37.9) and astrocytoma (HR = 10.1, 95% CI = 5.3 to 19.5). Three-year cumulative incidence of death after CNS subsequent malignant neoplasms, by treatment decade, were 76%, 74%, and 73%, respectively. Conclusion: CNS subsequent malignant neoplasm incidence has not decreased despite fewer survivors exposed to CNS-directed radiotherapy. CNS subsequent malignant neoplasm remains a substantial source of mortality for affected patients.

PURPOSE: Radiation-associated cardiac disease is a major cause of morbidity/mortality among childhood cancer survivors. Radiation dose-response relationships for cardiac substructures and cardiac diseases remain unestablished. METHODS: Using the 25,481 5-year survivors of childhood cancer treated from 1970 to 1999 in the Childhood Cancer Survivor Study, we evaluated coronary artery disease (CAD), heart failure (HF), valvular disease (VD), and arrhythmia. We reconstructed radiation doses for each survivor to the coronary arteries, chambers, valves, and whole heart. Excess relative rate (ERR) models and piecewise exponential models evaluated dose-response relationships. RESULTS: The cumulative incidence 35 years from diagnosis was 3.9% (95% CI, 3.4 to 4.3) for CAD, 3.8% (95% CI, 3.4 to 4.2) for HF, 1.2% (95% CI, 1.0 to 1.5) for VD, and 1.4% (95% CI, 1.1 to 1.6) for arrhythmia. A total of 12,288 survivors (48.2%) were exposed to radiotherapy. Quadratic ERR models improved fit compared with linear ERR models for the dose-response relationship between mean whole heart and CAD, HF, and arrhythmia, suggesting a potential threshold dose; however, such departure from linearity was not observed for most cardiac substructure end point dose-response relationships. Mean doses of 5-9.9 Gy to the whole heart did not increase the risk of any cardiac diseases. Mean doses of 5-9.9 Gy to the right coronary artery (rate ratio [RR], 2.6 [95% CI, 1.6 to 4.1]) and left ventricle (RR, 2.2 [95% CI, 1.3 to 3.7]) increased risk of CAD, and to the tricuspid valve (RR, 5.5 [95% CI, 2.0 to 15.1]) and right ventricle (RR, 8.4 [95% CI, 3.7 to 19.0]) increased risk of VD. CONCLUSION: Among children with cancer, there may be no threshold dose below which radiation to the cardiac substructures does not increase the risk of cardiac diseases. This emphasizes their importance in modern treatment planning.

PURPOSE: To evaluate long-term morbidity and mortality among unilateral, nonsyndromic Wilms tumor (WT) survivors according to conventional treatment regimens. METHODS: Cumulative incidence of late mortality (≥ 5 years from diagnosis) and chronic health conditions (CHCs) were evaluated in WT survivors from the Childhood Cancer Survivor Study. Outcomes were evaluated by treatment, including nephrectomy combined with vincristine and actinomycin D (VA), VA + doxorubicin + abdominal radiotherapy (VAD + ART), VAD + ART + whole lung radiotherapy, or receipt of ≥ 4 chemotherapy agents. RESULTS: Among 2,008 unilateral WT survivors, 142 deaths occurred (standardized mortality ratio, 2.9, 95% CI, 2.5 to 3.5; 35-year cumulative incidence of death, 7.8%, 95% CI, 6.3 to 9.2). The 35-year cumulative incidence of any grade 3-5 CHC was 34.1% (95% CI, 30.7 to 37.5; rate ratio [RR] compared with siblings 3.0, 95% CI, 2.6 to 3.5). Survivors treated with VA alone had comparable risk for all-cause late mortality relative to the general population (standardized mortality ratio, 1.0; 95% CI, 0.5 to 1.7) and modestly increased risk for grade 3-5 CHCs compared with siblings (RR, 1.5; 95% CI, 1.1 to 2.0), but remained at increased risk for intestinal obstruction (RR, 9.4; 95% CI, 3.9 to 22.2) and kidney failure (RR, 11.9; 95% CI, 4.2 to 33.6). Magnitudes of risk for grade 3-5 CHCs, including intestinal obstruction, kidney failure, premature ovarian insufficiency, and heart failure, increased by treatment group intensity. CONCLUSION: With approximately 40% of patients with newly diagnosed WT currently treated with VA alone, the burden of late mortality/morbidity in future decades is projected to be lower than that for survivors from earlier eras. Nevertheless, the risk of late effects such as intestinal obstruction and kidney failure was elevated across all treatment groups, and there was a dose-dependent increase in risk for all grade 3-5 CHCs by treatment group intensity.

PURPOSE: To describe the risk of late mortality, subsequent malignant neoplasms (SMNs), and chronic health conditions (CHCs) in survivors of neuroblastoma diagnosed in infancy by treatment era and exposures. METHODS: Among 5-year survivors of neuroblastoma in the Childhood Cancer Survivor Study diagnosed age < 1 year between 1970 and 1999, we examined the cumulative incidence of late (> 5 years from diagnosis) mortality, SMN, and CHCs (grades 2-5 and 3-5). Multivariable Cox regression models estimated hazard ratios (HRs) and 95% CIs by decade and treatment (surgery-alone v chemotherapy with or without surgery [C ± S] v radiation with or without chemotherapy ± surgery [R ± C ± S]) among survivors and between survivors and 5,051 siblings. RESULTS: Among 1,397 eligible survivors, the 25-year cumulative incidence of late mortality was 2.1% (95% CI, 1.3 to 3.9) with no difference by treatment era. Among 990 participants who completed a baseline survey, fewer survivors received radiation in more recent eras (51.2% 1970s, 20.4% 1980s, and 10.1% 1990s; P < .001). Risk of SMN was elevated only among individuals treated with radiation-containing regimens compared with surgery alone (HR_{[C ± S]}, 3.2 [95% CI, 0.9 to 11.6]; HR_{[R ± C ± S]}, 5.7 [95% CI, 1.2 to 28.1]). In adjusted models, there was a 50% reduction in risk of grade 3-5 CHCs in the 1990s versus 1970s (HR, 0.5 [95% CI, 0.3 to 0.9]; P = .01); individuals treated with radiation had a 3.6-fold risk for grade 3-5 CHCs (95% CI, 2.1 to 6.2) versus those treated with surgery alone. When compared with siblings, risk of grade 3-5 CHCs for survivors was lowest in the most recent era (HR_[1970s], 4.7 [95% CI, 3.4 to 6.5]; HR_[1980s], 4.6 [95% CI, 3.3 to 6.4]; HR_[1990s], 2.5 [95% CI, 1.7 to 3.9]). CONCLUSION: Neuroblastoma survivors treated during infancy have a relatively low absolute burden of late mortality and SMN. Encouragingly, risk of CHCs has declined in more recent eras with reduced exposure to radiation therapy.

PURPOSE: To evaluate the outcomes and cost-effectiveness of the Children's Oncology Group Guideline recommendation for breast cancer (BC) screening using mammography (MAM) and breast magnetic resonance imaging (MRI) in female chest-irradiated childhood Hodgkin lymphoma (HL) survivors. Digital breast tomosynthesis (DBT), increasingly replacing MAM in practice, was also examined. METHODS: Life years (LYs), quality-adjusted LYs (QALYs), BC mortality, health care costs, and false-positive screen frequencies of undergoing annual MAM, DBT, MRI, MAM + MRI, and DBT + MRI from age 25 to 74 years were estimated by microsimulation. BC risks and non-BC mortality were estimated from female 5-year survivors of HL in the Childhood Cancer Survivor Study and the US population. Test performance of MAM and MRI was synthesized from HL studies, and that of DBT from the general population. Costs (2017 US dollars [USD]) and utility weights were obtained from the medical literature. Incremental cost-effectiveness ratios (ICERs) were calculated. RESULTS: With 100% screening adherence, annual BC screening extended LYs by 0.34-0.46 years over no screening. If the willingness-to-pay threshold to gain a quality-adjusted LY was ICER < $100,000 USD, annual MAM at age 25-74 years was the only cost-effective strategy. When nonadherence was taken into consideration, only annual MAM at age 30-74 years (ICER = $56,972 USD) was cost-effective. Supplementing annual MAM with MRI costing $545 USD was not cost-effective under either adherence condition. If MRI costs were reduced to $300 USD, adding MRI to annual MAM at age 30-74 years could become more cost-effective, particularly in the reduced adherence condition (ICER = $133,682 USD). CONCLUSION: Annual BC screening using MAM at age 30-74 years is effective and cost-effective in female chest-irradiated HL survivors. Although annual adjunct MRI is not cost-effective at $545 USD cost, it could become cost-effective as MRI cost is reduced, a plausible scenario with the emergent use of abbreviated MRI.