The impact of timing of salvage hormonal therapy on survival after brachytherapy for prostate cancer

Purpose We aimed to evaluate the impact of timing of androgen deprivation therapy (ADT) on survival in a cohort of patients with biochemical recurrence (BCR) after brachytherapy treatment for prostate cancer. Methods and Materials We retrospectively identified 2366 men receiving permanent prostate brachytherapy with or without external beam radiation therapy. Patients experiencing BCR were stratified by receipt of immediate or delayed (≥3 months) ADT and prostate-specific antigen (PSA) failure threshold of 10 ng/mL. Prostate cancer–specific mortality (PCSM) and all-cause mortality (ACM) were evaluated using Fine–Gray's competing risks regression and Cox proportional hazard model, respectively. Results We identified 109 patients in the study cohort treated with ADT for BCR, followed for a median of 11.4 years. Competing risk regression revealed that there was no difference in PCSM for patients receiving delayed vs. immediate ADT (hazard ratio [HR], 0.94; 95% confidence interval [CI]: 0.44–2.00: p = 0.871) or for those initiating hormonal therapy at PSA threshold of 10 vs. <10 ng/mL (HR, 0.85; 95% CI: 0.41–1.75; p = 0.649); similarly, there was no difference in ACM. PSA doubling time <6 months (HR, 2.52; 95% CI: 1.22–5.23; p = 0.013), time to BCR <3 years (HR, 3.27; 95% CI: 1.67–6.42; p = 0.003), and permanent prostate brachytherapy with external beam radiation therapy (HR, 5.21; 95% CI: 2.05–13.26; p = 0.001) were significantly associated with PCSM, as well as ACM. Conclusions Among a cohort of brachytherapy patients, we identified no significant difference in survival for delayed salvage hormonal therapy. Shorter PSA doubling time and time to BCR are significantly associated with adverse outcomes, and these patients should be considered for immediate salvage therapy.