Subsequent Neoplasm Risk Associated With Rare Variants in DNA Damage Response and Clinical Radiation Sensitivity Syndrome Genes in the Childhood Cancer Survivor Study.

PURPOSE: Radiotherapy for childhood cancer is associated with elevated subsequent neoplasm (SN) risk, but the contribution of rare variants in DNA damage response and radiation sensitivity genes to SN risk is unknown. PATIENTS AND METHODS: We conducted whole-exome sequencing in a cohort of childhood cancer survivors originally diagnosed during 1970 to 1986 (mean follow-up, 32.7 years), with reconstruction of doses to body regions from radiotherapy records. We identified patients who developed SN types previously reported to be related to radiotherapy (RT-SNs; eg, basal cell carcinoma [BCC], breast cancer, meningioma, thyroid cancer, sarcoma) and matched controls (sex, childhood cancer type/diagnosis, age, SN location, radiation dose, survival). Conditional logistic regression assessed SN risk associated with potentially protein-damaging rare variants (SnpEff, ClinVar) in 476 DNA damage response or radiation sensitivity genes with exact permutation-based P values using a Bonferroni-corrected significance threshold of P < 8.06 × 10-5. RESULTS: Among 5,105 childhood cancer survivors of European descent, 1,108 (21.7%) developed at least 1 RT-SN. Out-of-field RT-SN risk, excluding BCC, was associated with homologous recombination repair (HRR) gene variants (patient cases, 23.2%; controls, 10.8%; odds ratio [OR], 2.6; 95% CI, 1.7 to 3.9; P = 4.79 × 10-5), most notably but nonsignificantly for FANCM (patient cases, 4.0%; matched controls, 0.6%; P = 9.64 × 10-5). HRR variants were not associated with likely in/near-field RT-SNs, excluding BCC (patient cases, 12.7%; matched controls, 12.9%; P = .92). Irrespective of radiation dose, risk for RT-SNs was also associated with EXO1 variants (patient cases, 1.8%; controls, 0.4%; P = 3.31 × 10-5), another gene implicated in DNA double-strand break repair. CONCLUSION: In this large-scale discovery study, we identified novel associations between RT-SN risk after childhood cancer and potentially protein-damaging rare variants in genes involved in DNA double-strand break repair, particularly HRR. With replication, these results could affect screening recommendations for childhood cancer survivors and risk-benefit assessments of treatment approaches.

Bone and Soft-Tissue Sarcoma Risk in Long-Term Survivors of Hereditary Retinoblastoma Treated With Radiation.

PURPOSE: Survivors of hereditary retinoblastoma have excellent survival but substantially increased risks of subsequent bone and soft-tissue sarcomas, particularly after radiotherapy. Comprehensive investigation of sarcoma risk patterns would inform clinical surveillance for survivors. PATIENTS AND METHODS: In a cohort of 952 irradiated survivors of hereditary retinoblastoma who were originally diagnosed during 1914 to 2006, we quantified sarcoma risk with standardized incidence ratios (SIRs) and cumulative incidence analyses. We conducted analyses separately for bone and soft-tissue sarcomas occurring in the head and neck (in/near the radiotherapy field) versus body and extremities (out of field). RESULTS: Of 105 bone and 124 soft-tissue sarcomas, more than one half occurred in the head and neck (bone, 53.3%; soft tissue, 51.6%), one quarter in the body and extremities (bone, 29.5%; soft tissue, 25.0%), and approximately one fifth in unknown/unspecified locations (bone, 17.1%; soft tissue, 23.4%). We noted substantially higher risks compared with the general population for head and neck versus body and extremity tumors for both bone (SIR, 2,213; 95% CI, 1,671 to 2,873 v SIR, 169; 95% CI, 115 to 239) and soft-tissue sarcomas (SIR, 542; 95% CI, 418 to 692 v SIR, 45.7; 95% CI, 31.1 to 64.9). Head and neck bone and soft-tissue sarcomas were diagnosed beginning in early childhood and continued well into adulthood, reaching a 60-year cumulative incidence of 6.8% (95% CI, 5.0% to 8.7%) and 9.3% (95% CI, 7.0% to 11.7%), respectively. In contrast, body and extremity bone sarcoma incidence flattened after adolescence (3.5%; 95% CI, 2.3% to 4.8%), whereas body and extremity soft-tissue sarcoma incidence was rare until age 30, when incidence rose steeply (60-year cumulative incidence, 6.6%; 95% CI, 4.1% to 9.2%), particularly for females (9.4%; 95% CI, 5.1% to 13.8%). CONCLUSION: Strikingly elevated bone and soft-tissue sarcoma risks differ by age, location, and sex, highlighting important contributions of both radiotherapy and genetic susceptibility. These data provide guidance for the development of a risk-based screening protocol that focuses on the highest sarcoma risks by age, location, and sex.

Patterns of Cause-Specific Mortality Among 2053 Survivors of Retinoblastoma, 1914-2016.

BACKGROUND: Previous studies of hereditary retinoblastoma survivors have reported elevated mortality, particularly for sarcomas, compared with the general population. However, cause-specific mortality patterns for long-term hereditary and nonhereditary retinoblastoma survivors are poorly understood. METHODS: Among 2053 retinoblastoma patients diagnosed during 1914-2006 at two major US treatment centers and followed to 2016, we estimated cumulative mortality, standardized mortality ratios (SMRs), and absolute excess risks (AERs) compared with the US general population. RESULTS: Most deaths occurred in 1129 hereditary retinoblastoma patients (n = 518 deaths, cumulative mortality 70 years after retinoblastoma = 75.8%, 95% CI = 69.0% to 82.6%; SMR = 8.5, 95% CI = 7.7 to 9.2). Of these, 267 were due to subsequent cancers (SMR = 27.4, 95% CI = 24.2 to 30.9; AER = 72.3 deaths/10 000 person-years), for which SMRs were highest 15-29 years after diagnosis (n = 69, SMR = 89.9, 95% CI = 70.0 to 113.8) but remained statistically significantly elevated at 60 and more years (n = 14, SMR = 6.7, 95% CI = 3.6 to 11.2), whereas AERs increased with time (AER<15years = 38.0; AER60+years = 327.5). Increased risk of death due to cancers of pancreas, large intestines, and kidney were noted for the first time. Overall risk of subsequent cancers was greater for those treated with radiotherapy and chemotherapy compared to radiotherapy alone, although patterns varied by organ site. For 924 patients with nonhereditary retinoblastoma, we noted a modestly increased risk of death for subsequent cancers (n = 27, SMR = 1.8, 95% CI = 1.2 to 2.6) possibly due to treatment or misclassification of hereditary status. Risks of noncancer causes of death were not elevated for hereditary or nonhereditary patients. CONCLUSION: Hereditary retinoblastoma survivors died mainly from an excess risk of subsequent cancers up to six decades later, highlighting the need to develop long-term clinical management guidelines for hereditary retinoblastoma survivors treated in the past.

Association of Chemotherapy for Solid Tumors With Development of Therapy-Related Myelodysplastic Syndrome or Acute Myeloid Leukemia in the Modern Era.

Importance: Therapy-related myelodysplastic syndrome or acute myeloid leukemia (tMDS/AML) is a rare, usually fatal complication of chemotherapy, including certain alkylating agents, topoisomerase II inhibitors, and platinum compounds. With the introduction of new chemotherapeutic agents, expanded indications for established agents, and increased neoadjuvant and adjuvant chemotherapy, tMDS/AML risks in the modern age are poorly understood. Objectives: To quantify tMDS/AML risk after chemotherapy for solid cancer among United States adults since 2000 and correlate tMDS/AML risk patterns with chemotherapy treatment practices. Design, Setting, and Participants: A population-based cohort study was conducted using cancer registries from the Surveillance, Epidemiology, and End Results (SEER) Program and Medicare claims. Risk analyses included 1619 tMDS/AML cases among 700 612 adults (age, 20-84 years) who were diagnosed with first primary solid cancer during 2000 to 2013 (followed up through 2014), received initial chemotherapy, and survived 1 year or longer, as reported to SEER. Descriptive analyses were conducted of SEER records linked with Medicare claims for chemotherapy in 165 820 older adults (age, 66-84 years) receiving initial chemotherapy for a first primary solid cancer in 2000-2013. Data analysis was conducted from October 2017 to April 2018. Exposures: Receipt of initial chemotherapy for solid cancer. Main Outcomes and Measures: Second primary tMDS/AML. Results: Based on 1619 tMDS/AML cases in the SEER database (mean [SD] age, 64.3 [12.2] years; 1148 [70.9%] female), tMDS/AML risks were statistically significantly elevated after chemotherapy for 22 of 23 solid cancers (all except colon). Relative risks ranged from 1.5 to greater than 10 and excess absolute risks from 1.4 to greater than 15 cases per 10 000 person-years compared with the general population. Overall survival following tMDS/AML diagnosis was poor (1270 of 1619 patients [78.4%] died; median overall survival, 7 months). For patients treated with chemotherapy at the present time, approximately three-quarters of tMDS/AML cases expected to occur within the next 5 years will be attributable to chemotherapy. In the SEER-Medicare database, use of known leukemogenic agents, particularly platinum compounds, in initial chemotherapy increased substantially since 2000, most notably for gastrointestinal tract cancers (esophagus, stomach, colon, and rectum; 10% in 2000-2001 to 81% during 2012-2013). Conclusions and Relevance: Large-scale, United States population-based data demonstrate excess tMDS/AML risks following chemotherapy for nearly all solid tumor types, consistent with expanded use of known leukemogenic agents in the 21st century. Continued efforts to reduce treatment-related adverse events, particularly for solid cancer patients with favorable prognosis, are needed.