Introduction: Bladder cancer (BCa) is three-to-four times more common in men than in women. To explain this gender gap, several theories have been proposed, including the impact of androgen hormones. The aim of this study was to investigate the differential impact of androgen deprivation therapy (ADT) on subsequent risk of developing BCa in men with prostate cancer (PCa).
Methods: A total of 196,914 patients diagnosed with histologically confirmed localized PCa between 2000 and 2009 were identified in the SEER-Medicare insurance program-linked database. Competing-risk regression analyses were performed to assess the risk of developing BCa adjusting for the risk of all-cause mortality. Univariable and multivariable competing-risk regression analyses were performed to test the effect of ADT on BCa incidence for each PCa treatment modality.
Results: Of the 196,914 individuals included in the study, 68,421 (34.7%) received ADT. Median (IQR) follow-up was 59 (29-95) months. Overall, a total of 2495 (1.3%) individuals developed BCa during follow-up. After stratification according to ADT, the 10-year cumulative incidence rate was 1.75% (95% CI 1.65-1.85). In the untreated group, the 10-year cumulative incidence rate was 1.99% (95% CI 1.83-2.15). In multivariable competing-risk regression, the use of ADT was not associated with BCa, after accounting for the risk of dying from any cause (p = 0.1).
Conclusion: We failed to identify any impact of ADT on the risk of developing a subsequent BCa even after stratifying according to the type of treatment. Further studies are required to explain the gender gap in BCa incidence and outcomes.
Keywords: ADT; Androgen deprivation treatment; Bladder cancer; Metastases; Prostate cancer; Survival.