Performance of MRI-Based vs Clinical T Staging in Localized Prostate Cancer.

Importance: Magnetic resonance imaging (MRI) is increasingly used for local staging in prostate cancer, yet its value relative to digital rectal examination (DRE) staging remains uncertain. Objectives: To compare the performance of MRI-based vs DRE-based clinical T staging in men undergoing radical prostatectomy (RP) and to assess the outcome of substituting MRI staging in established prognostic classification systems. Design, Setting, and Participants: This multicenter, retrospective case-control study (iTNM Consortium) was conducted from January 1, 2015, to December 31, 2021, among consecutive men 18 years or older with clinically localized or locally advanced prostate cancer who underwent RP and preoperative multiparametric MRI and systematic biopsies with or without targeted biopsies at 31 referral centers across 6 European countries. Patients receiving prior prostate cancer treatment or missing key variables were excluded. Data analysis was performed from August to October 2025. Exposures: MRI-derived T stage (iT) vs DRE-derived T stage (cT) incorporated into D'Amico, European Association of Urology, National Comprehensive Cancer Network, and International Staging Collaboration for Prostate Cancer risk groups to generate MRI-adapted classification systems. Main Outcomes and Measures: Primary outcome was distant metastasis-free survival. Secondary outcomes were biochemical recurrence-free survival and overall survival. Discrimination was assessed using a C index and time-dependent area under the receiver operating characteristic curves. Results: A total of 4425 men were included (median [IQR] age, 66 [61-70] years; median [IQR] prostate-specific antigen, 7.4 [5.5-10.5] ng/mL). Median (95% CI) follow-up was 52 (51-53) months. MRI-based staging showed slightly higher discriminatory ability than DRE staging for biochemical recurrence-free survival (C index, 0.62 [95% CI, 0.61-0.64] vs 0.59 [95% CI, 0.57-0.61]) and distant metastasis-free survival (0.67 [95% CI, 0.64-0.70] vs 0.65 [95% CI, 0.62-0.68]). However, across all 4 risk classification systems, MRI-based and DRE-based versions demonstrated comparable discrimination with overlapping 95% CIs. Time-dependent area under the receiver operating characteristic curves showed no significant difference during follow-up. Subgroup analyses of patients with cT1 disease and those with PSA levels less than 10 ng/mL yielded similar results. Conclusions and Relevance: In this case-control study of patients undergoing radical prostatectomy, MRI-based staging demonstrated discrimination similar to traditional DRE-based staging for biochemical recurrence, distant metastasis, and overall survival. These findings suggested that MRI-derived staging could be safely integrated into contemporary risk systems without compromising accuracy.