Excess risk of subsequent malignant neoplasms in adolescent and young adult cancer survivors: Results from the first Italian population-based cohort

Background: Evidence about late effects in adolescent and young adult (AYA) cancer survivors is scarce. This study assessed the risk of subsequent malignant neoplasms (SMNs) to identify the most common SMNs to be considered in follow-up care. Methods: Population-based cancer registries retrospectively identified first primary tumors (between 1976 and 2013) and SMNs in AYAs (15-39 years old at their cancer diagnosis). AYA cancer survivors were those alive at least 5 years after their first cancer diagnosis. The excess risk of SMNs was measured as standardized incidence ratios (SIRs) and absolute excess risk together with the cumulative incidence of SMNs. Results: The cohort included 67,692 AYA cancer survivors. The excess risk of developing any SMN (SIR, 1.6; 95% confidence interval, 1.5-1.7) was 60%. The excess risk of SMNs was significantly high for survivors of lymphomas; cancers of the breast, thyroid, female genital tract, digestive organs, gonads, and urinary tract; and melanomas. The cumulative incidence of all SMNs in AYA cancer survivors within 25 years of their first cancer diagnosis was approximately 10%. Subsequent tumors contributing to approximately 60% of all SMNs were breast cancer, colorectal cancer, corpus uteri cancer, and ovarian cancer in females and colorectal cancer, bladder cancer, prostate cancer, lung cancer, and lymphomas in males. Conclusions: These results highlight the need to personalize follow-up strategies for AYA cancer survivors.