Impact of androgen deprivation therapy in patients with unfavorable intermediate-risk prostate cancer receiving brachytherapy-based dose-escalated radiation therapy

Purpose: While the benefit of short-term androgen deprivation therapy (ADT) has been established for patients with intermediate-risk (IR) prostate cancer (PCa) receiving dose-escalated external beam radiation therapy (EBRT), the role of ADT for patients treated with brachytherapy (BT) with or without supplemental EBRT (sEBRT) is less clear.

Material and methods: We conducted a single-institution retrospective analysis of men with National Comprehensive Cancer Network (NCCN) unfavorable IR (UIR) PCa. All patients received BT with or without sEBRT, and were stratified by the receipt of 4-6 months of ADT. Kaplan-Meier method was used to measure biochemical progression- free survival (bPFS) between men who did vs. did not receive ADT. Multivariable Cox proportional hazards with backward selection was utilized to determine association of concomitant ADT with bPFS accounting for confounding variables.

Results: We identified 201 eligible patients treated between 2002 and 2019, 78 (38.8%) of whom received ADT. Median follow-up was 15 years. On univariable analysis, there was no significant association of ADT use with bPFS (HR = 0.95, 95% CI: 0.34-2.63, p = 0.92). Only PSA ≥ 10 was significant for association with worse bPFS (HR = 3.51, 95% CI: 1.29-9.52, p = 0.014). On multivariable analysis, there was no association of ADT use with bPFS (HR = 0.97, 95% CI: 0.34-2.78, p = 0.96).

Conclusions: Short-course ADT was not associated with improved bPFS in our study among men with UIR PCa treated with BT with or without sEBRT. These findings suggest that dose intensification achieved with BT may alone be sufficient in treating selected patients with UIR disease, but prospective studies are warranted.