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.

Background: Prostate cancer patients with intermediate disease risk [Gleason score (GS)7] can be divided into two groups: GS = 7(3 + 4) (ISUP 2) (favorable disease risk) and GS = 7(4 + 3) (ISUP 3) (unfavorable disease risk). Low-dose-rate brachytherapy (LDR-BT) is an effective treatment for low- and intermediate-disease-risk patients. Objectives: The main goal of this study was to evaluate the effectiveness of LDR-BT monotherapy in prostate cancer patients classified as ISUP 3 when compared with ISUP 2 patients. Methods: This was a retrospective study that evaluated prostate cancer patients classified as ISUP 2 and ISUP 3 followed up at the Center for the Treatment of Urological Diseases, Portugal, who underwent LDR-BT. Overall survival (OS), biochemical recurrence-free survival (BRFS), bone metastasis and complications post-LDR-BT treatment were evaluated. Results: A total of 602 patients classified with GS = 7 (481/602 ISUP 2 and 121/602 ISUP 3) treated with LDR-BT were recruited. High OS rates and a reduced frequency of complications were described in both groups of patients. ISUP 3 patients had a lower BRFS rate, a higher risk of biochemical recurrence, and developed more bone metastasis in a shorter period when compared with ISUP 2 patients. No significant differences were detected in prostate-cancer-specific mortality between groups. Conclusions: LDR-BT monotherapy is a safe and effective treatment for prostate cancer patients with favorable and unfavorable intermediate disease risk, with similar OS rates and reduced complications.