Impact of PI-RADS During Active Surveillance for Prostate Cancer on Pathological Findings at Repeat Biopsy.

BACKGROUND/AIM: This study aimed to determine whether lesion visibility on magnetic resonance imaging (MRI) predicts rebiopsy outcomes during active surveillance for prostate cancer. PATIENTS AND METHODS: We retrospectively analyzed data from 111 patients enrolled in the Prostate Cancer Research International Active Surveillance study (Japan) at Kagawa University (January 2010-February 2025). After excluding 19 patients who discontinued active surveillance within one year, 92 patients were included in the analysis. MRI findings were classified as visible [Prostate Imaging Reporting and Data System (PI-RADS) score ≥3] or invisible (score ≤2). We assessed the association between visibility and rebiopsy outcomes, defined as reclassification progression beyond active surveillance criteria or no cancer. RESULTS: MRI was performed at diagnosis in 32.6% (n=32) of patients, at one year in 37.0% (n=34), and at four years in 47.7% (n=21). Lesion visibility at diagnosis was not associated with continuation of active surveillance compared with invisibility [median 43 months, 95% confidence interval (12-not available) vs. not available (17-not available), p=0.404]. However, at the 1-year rebiopsy, reclassification occurred significantly more frequently in patients with visible lesions than in those with invisible lesions (42.1% vs. 7.1%, p=0.047). Conversely, no cancer was more common in patients with invisible lesions (50.0% vs. 10.5%, p=0.019). CONCLUSION: At one year, a PI-RADS score ≥3 was associated with a higher risk of reclassification, whereas a score ≤2 was associated with a greater likelihood of no cancer on rebiopsy. These findings highlight the prognostic value of MRI in guiding active surveillance.