Active Surveillance for Localized Prostate Cancer: A Retrospective Single‐Center Study

BACKGROUND: Active surveillance (AS) offers a strategy to limit unnecessary treatment of prostate cancer while maintaining oncologic safety, yet its adoption in Japan remains limited. To provide Japan-specific evidence, we evaluated the clinical outcomes of patients undergoing AS at our institution. METHODS: We retrospectively reviewed 86 patients who selected AS between 2012 and 2024. Eligibility criteria included ≤ cT2a disease, prostate-specific antigen (PSA) level of ≤ 10 ng/mL, Gleason score (GS) of 3 + 3, and 2 or fewer positive cores, with selected inclusion of GS 3 + 4 or 4 + 3 based on patient preference. AS discontinuation was based on clinical or pathological progression or patient preference. This study was approved by the institutional review board of Gunma University (approval no. IRB2025-033, 2310). RESULTS: The mean observation period was 48 months. No prostate cancer-specific deaths occurred. AS persistence rates were 89% at 1 year, 55% at 5 years, and 27% at 10 years. Older age (≥ 75 years) was associated with longer AS persistence (p = 0.021). Overall, 69% of patients underwent repeat biopsy, most commonly at 1 year. Pathological upgrading occurred in 35% at the first and second repeat biopsies and in 20% at the third. Acceptance of the 1-year repeat biopsy increased from 46% in the early period (2012-2016) to 64% in the later period (2017-2024). CONCLUSIONS: AS demonstrated favorable long-term safety and durability. Improving adherence to repeat biopsy protocols may further enhance AS management in Japan. REGISTRY AND REGISTRATION NO. OF THE STUDY/TRIAL: N/A.