Background: We assessed the risk of prostate cancer-specific mortality (PCSM) in men with unfavorable and favorable intermediate-risk prostate cancer (PC) who received dose-escalated radiotherapy (RT) with or without short-course androgen deprivation therapy (ADT). Methods: The cohort consisted of 2,668 men with intermediate-risk PC (71.3% favorable, 28.7% unfavorable) who were treated with dose-escalated RT with or without ADT (median 4 mos.) from 1997 - 2013. Fine and Gray's competing risks regression was used to assess whether ADT decreased PCSM-risk in an adjusted multivariable model (Table). An interaction term was included to assess for potential differences in the impact of ADT on PCSM risk in men with favorable versus unfavorable intermediate-risk PC. Results: After a median follow-up of 7.84 years, there were 393 deaths (14.73%), of which 33 were from PC (8.40%). There was significant reduction in PCSM-risk in men with unfavorable intermediate-risk PC who received ADT (AHR 0.39, 95% CI 0.16 to 0.92, P=0.033), but no significant difference in PCSM-risk in men with favorable intermediate-risk PC who received ADT (AHR 0.68, 95% CI 0.19 to 2.49, P=0.561). Conclusions: While ADT reduced PCSM-risk in men with unfavorable intermediate-risk PC, there was no significant improvement in men with favorable intermediate-risk PC, suggesting that for these patients ADT in addition to dose-escalated RT may not be required to minimize PCSM-risk.

^ Within interaction model, AHR for high-dose RT with versus without ADT within favorable intermediate-risk PC is 0.68 [95% CI, 0.19 to 2.49, P=0.561].