Impact of Clinicopathological and Institutional Factors on the Clinical Courses of Patients With Localized Prostate Cancer Initially Managed by Active Surveillance: An Analysis of Nationwide Real-World Data From Japan.

OBJECTIVES: To investigate active surveillance (AS) continuation rates and associated clinical and institutional factors in Japanese patients with localized prostate cancer. METHODS: We retrospectively analyzed 989 patients with localized prostate cancer from 92 institutions who initiated AS between 2016 and 2018. Institutions were categorized into three groups based on AS uptake for low-risk disease. Discontinuation triggers and subsequent treatments were examined. RESULTS: Median age was 70 years; 66.2%, 26.0%, and 7.8% of patients had low-, intermediate-, and high-risk disease, respectively. Over a median follow-up of 3.4 years, 47.0% discontinued AS (median AS continuation time: 3.0 years; 5-year AS continuation rate: 33.7%). Multivariable analysis showed that ≥ 2 comorbidities, ≥ 3 positive biopsy cores, and T2b-c stage were associated with restricted mean continuation time differences (RMCTDs) of -0.6, -0.6, and -0.8 years, respectively (all p < 0.05). Conversely, intermediate- and high-AS uptake institutions had significantly longer adjusted RMCTD (1.0 and 1.1 years, respectively; both p < 0.001). Triggers for discontinuation were more often multifaceted in high-AS uptake institutions (39.1%) compared with low- or intermediate-AS uptake institutions (16.2% and 15.1%, respectively). After discontinuation, 36.5%, 39.2%, and 24.3% of patients received prostatectomy, radiotherapy, and hormonal therapy, respectively. With advancing age, the proportion of patients whose AS was discontinued due to PSA elevation increased, as did the rate of subsequent hormonal therapy. CONCLUSIONS: In Japanese real-world practice, AS continuation was limited. Beyond clinicopathological factors, institutional strategies for localized prostate cancer played a significant role in treatment choices following AS.