Purpose: We evaluated a large disease registry to determine the incidence of bladder cancer in patients with prostate cancer and investigate whether the type of treatment for prostate cancer increased the risk of bladder cancer.
Materials and methods: We analyzed the CaPSURE disease registry for men diagnosed with prostate cancer plus bladder cancer between 1989 and 2003. Demographics, comorbidities and prostate cancer treatment modalities were compared in patients with and without bladder cancer. A backward stepwise Cox proportional hazards regression model was used to predict bladder cancer onset after treatment for prostate cancer in patients who had bladder cancer 30 days or greater after prostate cancer treatment.
Results: Of 9,780 patients from CaPSURE 143 (1.46%) also had bladder cancer. Patients with bladder cancer and prostate cancer were older (p<0.01) and more likely to be white (p=0.03), and they had lower levels of income (p<0.01) and education (p=0.04) than patients with prostate cancer only. Comorbidities did not differ between patients with and without bladder cancer. Patients treated with radical prostatectomy were approximately half as likely to have posttreatment bladder cancer as patients who underwent radiation therapy (HR 0.51, 95% CI 0.29-0.89). Patients who smoked had an independent increase in the risk of bladder cancer (HR 2.08, 95% CI 1.09-3.97), while smokers treated with radiation therapy were at almost 4-fold risk for bladder cancer (HR 3.65, 95% CI 1.45-9.16).
Conclusions: The incidence of bladder cancer in patients with prostate cancer was 1.5%. Radiation therapy and smoking increased the risk of bladder cancer.