Carlos Rabaça, Domingos Sanchez Roda, Guy Antoine Vieira, Bruno J. Pereira, Ricardo Godinho, Mário Lourenço, José Alberto Pereira, Margarida Regencio, Sofia Macedo, Amílcar Sismeiro
Background/Objectives: Prostate cancer is one of the most common malignancies diagnosed in men worldwide. Brachytherapy (BT), particularly low-dose rate (LDR)-BT, has been shown to be a successful treatment. The aim of this study was to evaluate the effectiveness of BT treatment in localized prostate cancer patients from a single-center Portuguese cohort. Methods: This was a retrospective study that evaluated prostate cancer patients followed up at the Center for the Treatment of Urological Diseases, Coimbra, Portugal, who underwent LDR-BT between November 2007 and March 2024. Overall survival (OS), biochemical recurrence-free survival (BRFS) and complications post-LDR BT treatment were evaluated during patients’ follow-up time. Results: A total of 1343 patients treated with LDR-BT were recruited. Global OS and BRFS rates were 98.4% and 87.7%, respectively. A reduced frequency of complications such as lower urinary tract symptoms, erectile dysfunction, acute urinary retention, radiation proctitis and stress urinary incontinence were described. High OS (>98%) and BRFS rates were observed particularly in low and intermediate disease risk. Prostate-specific antigen (PSA) serum levels > 20 ng/mL, Gleason score (GS) ≥ 8 and clinical tumor stage (cT) ≥ T2c were identified as the strongest predictors of death and/or biochemical recurrence. Conclusions: BT is an effective treatment in localized prostate cancer patients, with comparable outcomes and consistent with the OS and BRFS rates reported in the current literature for radical prostatectomy and external beam radiotherapy approaches, and with a reduced frequency of complications. PSA serum levels > 20 ng/mL, GS ≥ 8 and cT stage ≥ T2c can be used as strong predictors of death and/or biochemical recurrence during patients’ follow-up.