Secondary Bladder Cancers Following Prostate Cancer Treatment Modalities - Expert Commentary
The investigators collected data for 261609 age-matched patients from the Surveillance, Epidemiology, and End Results (SEER) database. The overall median age was 64 years, and the median follow-up time was 11.6 years. The cohort consisted of the following treatment subgroups: radical prostatectomy (RP, n=135024), EBRT (n=67512), BT (n=33756), EBRT + BT (n=16878), and RP to EBRT (n=8439). In the final matched cohort, 4876 patients had bladder cancer, and 6891 patients had lung cancer. The incidences of bladder cancer per 100 person-years were 0.12, 0.22, 0.24, 0.23, and 0.15 for RP, EBRT, BT, EBRT + BT, and RP-to-EBRT, respectively. Cox analyses generated the probability of bladder or lung cancer diagnosis. The hazard ratios for bladder cancer among EBRT, BT, EBRT + BT, and RPtoEBRT subgroups were 1.72, 1.85, 1.80, and 1.53, respectively (RP as a reference; p < 0.001). For bladder cancer death, HRs were 2.39, 2.57, 3.02, and 1.43 for EBRT, BT, EBRT + BT, and RPtoEBRT, respectively (p < 0.001, except RPtoEBRT, p = 0.28). For lung cancer, HRs were 1.63, 1.32, 1.42, and 1.30 for diagnosis and 1.73, 1.36, 1.38, and 1.08 for death for EBRT, BT, EBRT + BT, and RPtoEBRT, respectively (p < 0.001, except for RPtoEBRT in lung cancer death where p = 0.47). Older age was significantly associated with all measured outcomes (p < 0.001), while Caucasian race was significantly associated with bladder cancer diagnosis and death (p < 0.001). In terms of grades, there was a significantly greater proportion of muscle-invasive T2 bladder cancer (16.4% versus 13.2%, p = 0.0024) and T3 bladder cancer (6.4% versus 4.4%, p = 0.0033) in the radiation group. There was a significantly higher proportion of sarcomatoid cases in bladder cancers after radiation (p = 0.0076).
These findings indicate a higher risk of bladder cancer diagnosis after all forms of radiation. One of the key features of this study is the long follow-up interval that exceeds the median latency to bladder cancer diagnosis of 7.4 years. One of the study's limitations is the limited availability of other relevant clinical data in the SEER database. Characterizing the biological features that distinguish radiation-induced bladder cancer is critical for understanding the pathways that lead to radiation-induced carcinogenesis in the urinary bladder.
Written by: Bishoy M. Faltas, MD, Director of Bladder Cancer Research, Englander Institute for Precision Medicine, Weill Cornell Medicine
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