Salvage brachytherapy for local recurrence of prostate cancer. Evaluation of technique and dose fractionation, impact of early diagnosis, and its effect on survival. A multicenter retrospective observational study: RESPRO.

[PURPOSE] To evaluate oncologic outcomes, prognostic factors, and toxicity associated with salvage brachytherapy in locally recurrent prostate cancer after radiotherapy and assess the role of next-generation imaging in early detection.

[METHODS] A retrospective, multicenter cohort study was conducted including 188 patients treated with salvage HDR or LDR brachytherapy, with or without androgen deprivation therapy (ADT), across 10 Spanish centers. Primary endpoints were biochemical relapse-free survival (bRFS), clinical relapse-free survival (CRFS), and overall survival (OS). Survival probabilities were estimated using the Kaplan-Meier method, and predictive factors assessed using Cox proportional hazards models.

[RESULTS] With a median follow-up of 64.6 months, 5- and 10-year bRFS were 64.9% and 61.7%, and CRFS were 72.3% and 68.1%, respectively. OS at 5 and 10 years was 97.9% and 93.6%. Time to PSA nadir and lower nadir values were associated with improved bRFS and CRFS. Gleason score >7 and higher PSA at recurrence predicted worse outcomes. Next-generation imaging enhanced early detection. BED >216 Gy improved control but raised urinary toxicity. Grade 3 acute and late urinary toxicity rates were 2.8% and 3.1%, respectively.

[CONCLUSIONS] Salvage brachytherapy is an effective option for locally recurrent prostate cancer. PSA dynamics and advanced imaging improve patient selection. BED optimization remains critical.