Both androgen deprivation therapy (ADT) and radiation therapy (RT) are associated with a reduced risk of secondary bladder cancer in prostate cancer (PCa) patients, according to a new study presented at the 2016 Genitourinary Cancers Symposium in San Francisco.
The results corroborate previous research demonstrating reduced rates of primary and recurrent urothelial bladder cancer (UBC) in PCa patients treated with ADT. The investigators noted that men are more likely than women to develop UBC, indicating a possible role of androgens in cancer development.
“The finding of decreased UBC incidence in patients receiving RT was surprising, and in direct contradiction to previous studies of similar patient populations,” according to Daniel P. Petrylak, MD, professor at Yale School of Medicine, and colleagues. “Possible explanations include differences in cohort selection, changes in RT delivery, and differences in control group.”
The researchers used the Surveillance, Epidemiology, and End Results (SEER)-Medicare database to identify seniors (aged 66–99 years) diagnosed with PCa during 1999–2011. Of 121,927 primary PCa patients, 1,466 (1.2%) subsequently developed UBC over a median follow-up of 5 years.
The odds of UBC were reduced by 24% for patients who received ADT only, 27% for patients who received RT only, and 31% for patients who underwent both ADT and RT, compared with patients who never received these treatments. The investigators performed two-sided analyses with more than 14,000 patients in each group.
Additional research is warranted to understand the impact of pelvic radiation on the development of bladder cancer.