Solid and Hematologic Neoplasms After Testicular Cancer: A US Population-Based Study of 24 900 Survivors

Background No large US population-based study focusing on recent decades, to our knowledge, has comprehensively examined risks of second malignant solid and hematological neoplasms (solid-SMN and heme-SMN) after testicular cancer (TC), taking into account initial therapy and histological type. Methods Standardized incidence ratios (SIR) vs the general population and 95% confidence intervals (CI) for solid-SMN and heme-SMN were calculated for 24 900 TC survivors (TCS) reported to the National Cancer Institute’s Surveillance, Epidemiology, and End Results registries (1973–2014). All statistical tests were two-sided. Results The median age at TC diagnosis was 33 years. Initial management comprised chemotherapy (n = 6340), radiotherapy (n = 9058), or surgery alone (n = 8995). During 372 709 person-years of follow-up (mean = 15 years), 1625 TCS developed solid-SMN and 228 (107 lymphomas, 92 leukemias, 29 plasma cell dyscrasias) developed heme-SMN. Solid-SMN risk was increased 1.06-fold (95% CI = 1.01 to 1.12), with elevated risks following radiotherapy (SIR = 1.13, 95% CI = 1.06 to 1.21) and chemotherapy (SIR = 1.36, 95% CI = 1.12 to 1.41) but not surgery alone (SIR = 0.83, 95% CI = 0.75 to 0.92). Corresponding risks for seminoma were 1.13 (95% CI = 1.06 to 1.21), 1.28 (95% CI = 1.02 to 1.58), and 0.87 (95% CI = 0.74 to 1.01) and for nonseminoma were 1.05 (95% CI = 0.67 to 1.56), 1.25 (95% CI = 1.08 to 1.43), and 0.80 (95% CI = 0.70 to 0.92), respectively. Thirty-year cumulative incidences of solid-SMN after radiotherapy, chemotherapy, and surgery alone were 16.9% (95% CI = 15.7% to 18.1%), 10.1% (95% CI = 8.8% to 11.5%), and 8.8% (95% CI = 7.8% to 9.9%), respectively (P < .0001). Increased leukemia risks after chemotherapy (SIR = 2.68, 95% CI = 1.70 to 4.01) were driven by statistically significant sevenfold excesses of acute myeloid leukemia 1 to 10 years after TC diagnosis. Risks for lymphoma and plasma cell dyscrasias were not elevated. Conclusions We report statistically significant excesses of solid-SMN affecting 1 in 6 TCS 30 years after radiotherapy, and 2.7-fold risks of leukemias after chemotherapy, mostly acute myeloid leukemia. Efforts to minimize chemotherapy and radiotherapy exposures for TC should continue. TCS should be counseled about cancer prevention and screening.