Introduction:

The comparative rates of bladder cancer among patients treated for prostate cancer with prostatectomy (RP), external beam radiation therapy (EBRT), and brachytherapy (BT) in long-term follow up is not well known. Current studies comparing RP and EBRT are plagued by limitations. We aim to characterize the risk of bladder cancer after prostate cancer treatment as well as characterize the stage and histology of these bladder cancers.

Methods:

Using the 2000 to 2019 SEER database, we identified 418,053 patients treated for prostate cancer with RP, BT, or EBRT as well as those treated with RP followed by EBRT. We excluded all patients with a diagnosis of bladder cancer before or at the time of prostate cancer treatment and those without at least 12 months of follow up. Our primary analysis was a Cox proportional hazards model using time to bladder cancer diagnosis as the event of interest while adjusting for patient age.   

Results:

The adjusted hazard ratio of bladder cancer diagnosis after prostate cancer treatment, compared to RP, was 2.39 (95%CI 2.22 - 2.58) for BT, 2.49 (95%CI 2.34-2.64) for EBRT, and 1.45 (95%CI 1.22 -1.73) for RP followed by EBRT. Bladder cancers diagnosed after radiation (all groups), compared to those diagnosed after RP, were not significantly more likely to be muscle invasive (16.6% vs 14.6%, p=0.054) nor high grade (36.5% vs 36.7%, p=0.87) although variant histology (micropapillary or sarcomatoid) was more common in bladder cancers after radiation (0.7% vs 0.3%, p<0.01)

Conclusion:

Increased rates of bladder cancer are observed after prostate cancer treatment with EBRT and BT compared to patients treated with RP. The rate is less pronounced for patients whom underwent initial RP then EBRT. 

Funding: N/A