Should MRI-invisible low-risk prostate cancer be managed differently? A retrospective study of upgrading risk and future intervention.

[PURPOSE] Active surveillance is the standard of care for men with low-risk prostate cancer (CaP). However, ideal, risk-adapted frequencies of protocol-driven biopsies is undetermined. Magnetic resonance imaging (MRI) visible CaP with high MRI Prostate Imaging Reporting and Data System (PI-RADS) score is prognostic for progression during surveillance. Here we explore the implications of MRI invisibility on outcomes of low-risk CaP.

[METHODS] We retrospectively identified men undergoing prostate MRI since 2018 who were diagnosed with unilateral Gleason Grade Group 1 disease on initial biopsy. Inclusion was limited to patients receiving a subsequent repeat/confirmatory biopsy. MRI visibility was defined as PI-RADS ≥3 lesion(s) ipsilateral to Grade Group 1 disease. We analyzed differences in baseline and outcome variables between MRI-visible and MRI-invisible groups. Predictors of ipsilateral upgrading and future CaP intervention were identified via Cox regression, and Kaplan-Meier curves were plotted for upgrading and treatment-free survival.

[RESULTS] We identified 233 patients where 150 had MRI-visible and 83 had MRI-invisible unilateral GG1 disease. Groups were similar except for maximum PI-RADS score on MRI. The 2-year ipsilateral upgrading-free survival was 77% and 36% for MRI-invisible and MRI-visible groups, respectively. On multivariable analysis, MRI visibility (hazard ratio = 2.89, 95% confidence interval: 1.54-5.42, P < 0.001), PSA density, and presence of inflammation were independently predictive of ipsilateral upgrading. Predictors of future intervention were similar, with MRI visibility remaining significant (hazard ratio = 2.07, 95% confidence interval: 1.20-3.56; P = 0.008) on multivariable models.

[CONCLUSIONS] MRI visibility on initial imaging predicts pathologic upgrading and future intervention among men with low-risk CaP. MRI findings may help refine risk stratification in men considered for active surveillance.