Long-term outcomes of high-dose-rate brachytherapy combined with moderately hypofractionated external beam radiotherapy for high-risk localized prostate cancer

BACKGROUND: High-dose-rate brachytherapy (HDR-BT) combined with external beam radiotherapy (EBRT) is an established dose-escalation strategy for high-risk localized prostate cancer; however, long-term outcomes using a streamlined schedule with moderately hypofractionated EBRT and single-day HDR-BT remain insufficiently reported. METHODS: We retrospectively reviewed 110 patients with high-risk localized prostate cancer treated between 2008 and 2012 with EBRT (45 Gy in 15 fractions; 3 fractions/week) followed by single-day HDR-BT (9 Gy × 2 fractions). Most patients received 12 months of combined androgen blockade. Toxicity was graded using Radiation Therapy Oncology Group criteria. Biochemical relapse-free survival (bRFS) and overall survival (OS) were estimated using the Kaplan-Meier method. Cox regression was performed to identify predictors of biochemical recurrence. RESULTS: After a median follow-up of 127 months, the 10-year OS and bRFS rates were 92.7% and 74.0%, respectively. Late grade ≥ 3 genitourinary toxicity occurred in 1.8% of patients, and no grade ≥ 3 gastrointestinal toxicity was observed. Most adverse events were managed conservatively. In multivariate analysis, pretreatment PSA was significantly associated with biochemical recurrence (P = 0.012). CONCLUSIONS: Moderately hypofractionated EBRT combined with single-day HDR-BT produced durable long-term biochemical control with a favorable late-toxicity profile in high-risk localized prostate cancer. This streamlined schedule may be a practical combined-modality option and merits confirmation in broader, multi-institutional cohorts.