PURPOSE: External-beam radiation therapy (EBRT) may predispose to secondary malignancies that include bladder cancer (BCa), rectal cancer (RCa), and lung cancer (LCa). We tested this hypothesis in a large French Canadian population-based cohort of prostate cancer patients. METHODS AND MATERIALS: Overall, 8,455 radical prostatectomy (RP) and 9,390 EBRT patients treated between 1983 and 2003 were assessed with Kaplan-Meier and Cox regression analyses. Three endpoints were examined: (1) diagnosis of secondary BCa, (2) LCa, or (3) RCa. Covariates included age, Charlson comorbidity index, and year of treatment. RESULTS: In multivariable analyses that relied on incident cases diagnosed 60 months or later after RP or EBRT, the rates of BCa (hazard ratio [HR], 1.4; p = 0.02), LCa (HR, 2.0; p = 0.004), and RCa (HR 2.1; p
