Seven-Year PSA ≤ 0.2 ng/mL After High-Dose-Rate Brachytherapy Indicates Eligibility for Discontinuing PSA Surveillance in Prostate Cancer.

BACKGROUND: We evaluated the long-term treatment outcomes of patients with clinically localized and locally advanced prostate cancer (PC) who underwent high-dose-rate brachytherapy (HDR-BT) combined with external beam radiotherapy (EBRT). The primary objective was to identify the optimal timing for discontinuing prostate-specific antigen (PSA) monitoring after HDR-BT. METHODS: This analysis included 338 patients with PC who received HDR-BT combined with EBRT between 2006 and 2022 and had a minimum follow-up of 5 years. The patients were stratified based on their PSA levels, and factors associated with recurrence were identified. RESULTS: The median observation period was 8.9 years (range, 5.0-19.0 years). The 10-year recurrence-free survival rate was 92.0%, with 26 recurrences. PSA levels at 5 and 7 years were significantly correlated with oncological outcomes after HDR-BT. Multivariate analysis revealed that a PSA level of >0.2 ng/mL at 5 years was an independent poor prognostic factor for recurrence (hazard ratio, 117.57; 95% confidence interval, 6.22-2223.37; p = 0.001). No patient with a PSA level of ≤0.2 ng/mL at 7 years developed recurrences. CONCLUSIONS: Based on our long-term data, we propose that PSA monitoring may be safely discontinued in patients with a PSA level of ≤0.2 ng/mL 7 years after HDR-BT because the risk of recurrence beyond this point is exceedingly low.