Multiparametric Magnetic Resonance Imaging Alone is Insufficient to Detect Grade Reclassification in Active Surveillance for Prostate Cancer.

Multiparametric magnetic resonance imaging (mpMRI) has improved the detection of clinically significant prostate cancer. It remains unclear, however, whether mpMRI can safely replace confirmatory or surveillance biopsies in men with low-risk disease managed with active surveillance (AS). Overall, 166 men were upgraded at a median of 29 mo (interquartile range 13-54). The overall negative predictive value (NPV) of mpMRI was 79.5% and ranged from 74.4% to 84.6% for all AS biopsies up to the fourth surveillance biopsy. In men with prostate-specific antigen density ≥0.15 ng/ml/cm, the overall NPV of mpMRI was 65.5% and ranged from 57.1% to 73.3% across serial mpMRI scans. These findings support the hypothesis that mpMRI is helpful but insufficient to rule out pathological reclassification, especially at confirmatory biopsy or in the presence of other risk factors. PATIENT SUMMARY: Multiparametric magnetic resonance imaging (mpMRI) alone misses a considerable percentage of clinically significant prostate cancers (Gleason grade group ≥2) in men on active surveillance for low-risk prostate cancer. We conclude that mpMRI alone cannot safely replace surveillance prostate biopsies, particularly at confirmatory biopsy or in the presence of other risk factors.