Real-world monitoring strategies and predictors guiding the transition from active surveillance to treatment in ISUP 1 prostate cancer

PURPOSE: Active surveillance (AS) is the standard approach for managing ISUP 1 prostate cancer (PCa), ensuring oncological safety while minimizing overtreatment. However, AS protocols vary significantly. This study assessed a structured AS protocol incorporating PSA kinetics, multiparametric MRI (mpMRI), and targeted biopsies to identify predictors of treatment transition. METHODS: We retrospectively reviewed 89 patients with ISUP 1 PCa managed with AS between 2010 and 2024. Inclusion criteria were PSA < 10 ng/mL and ≤ 2 positive biopsy cores with ≤ 50% tumor involvement per core. Patients underwent regular PSA testing, mpMRI, and risk-adapted biopsies. Outcomes included treatment conversion, progression predictors, and the role of mpMRI. RESULTS: Median follow-up was 52.8 months. PSA was monitored at a median interval of 4.8 months, and mpMRI every 15.7 months (median). At diagnosis, 68.5% underwent mpMRI, with PIRADS 4 as the most frequent. During AS, 66.3% underwent at least one re-biopsy, most commonly triggered by PSA progression (73%). Treatment was initiated in 37.1% after a median of 37.9 months due to PSA progression (54.5%), mpMRI changes (21.2%), combined PSA/mpMRI findings (6.1%), histological upgrading (9.1%), or patient preference (3%). Treatments included radical prostatectomy, EBRT or LDR brachytherapy. Among these patients, no PSA persistence was observed; biochemical recurrence occurred in 6.1%, metastases in 4.0%, and overall mortality in 4.5%, with no PCa-specific deaths. CONCLUSION: A structured, risk-adapted AS protocol using PSA kinetics and mpMRI enabled personalized management and timely detection of progression. These findings support the standardization of AS protocols, which should be validated in larger cohorts.