Key points are not available for this paper at this time.
Abstract Purpose: Long-term survival can be achieved in patients with localized prostate cancer (PCa) treated with radical prostatectomy (RP) or radiotherapy (RT). However, secondary bladder cancer (BCa) development remains poorly understood. We investigated the effect of primary PCa treatment on the subsequent risk of developing a second primary BCa. Methods: We compared men who underwent RT for PCa with those who underwent RP. In total, 60195 patients with PCa were registered in the Kanagawa Cancer Registry between 1959 and 2017. Our primary objective was to investigate the effects of RT and RP on the incidence of secondary BCa. Cumulative incidence plots and multivariable Cox regression models were tested for second BCa rate differences according to the treatment type (RT vs. RP). Cumulative incidence was calculated as the competing risk of mortality. Hazard ratios were calculated using the fine-gray proportional hazards regression model. Results: Of the 60195 individuals included in the study, 8090 were treated with RT, and 12387 were treated with RP. Median follow-up was 69.3 months (1.0-486.4 months). The cumulative incidence of secondary BCa did not differ between patients treated with RT (3.78%) and those treated with RP (1.39%, p < 0.05). There was an increased risk of BCa (hazard ratio 1.70, 95% confidence interval 1.24 to 2.31) after RT compared with the risk in individuals after RP. Conclusions: Patients treated with RT are at an increased risk of developing a second primary BCa compared with those treated with RP.
Terao et al. (Wed,) studied this question.