Incidence of second primary malignancies in metastatic castration-resistant prostate cancer: results from observational studies in three countries.

Aim: This reports some of the first incidence rate (IR) estimates of second primary malignancies (SPMs) in men with metastatic castration-resistant prostate cancer (mCRPC) in three countries. Patients & methods: Claims data from the German Pharmacoepidemiological Research Database; registry data from the Prostate Cancer Data Base Sweden; and combined registry-claims data from the US Surveillance, Epidemiology and End Results-Medicare database were analyzed to obtain overall survival and incidence of SPMs in men with mCRPC. Results: SPMs occurred in 308 German (n = 2360), 273 Swedish (n = 2849) and 172 US (n = 2234) men with mCRPC. IRs of SPMs were 79.0 (95% CI: 70.4-88.4), 101.7 (95% CI: 90.3-114.5) and 59 (95% CI: 50-68) per 1000 person-years in German, Swedish and US cohorts, respectively. Conclusion: These studies report some of the first IR estimates of SPMs in men with mCRPC, providing a historical risk estimate of SPM in this patient population.