The purpose of this research was to evaluate the oncological outcomes of an active surveillance program in the intermediate term, wherein serial multiparametric magnetic resonance imaging would replace confirmatory biopsy. 

This was a single-arm, prospective experiment, and it had 172 male participants. The study comprised men with Gleason-eligible prostate cancer (Gleason 3+3=6 or Gleason 3+4=7 with ≤10% Gleason pattern 4 overall and <2 cores Gleason pattern 4). Initial multiparametric magnetic resonance imaging MRI and template targeted biopsy was performed on males, followed by additional MRIs after 1 and 2 years, and finally an end-of-protocol biopsy was performed at 3 years. Abnormalities on multiparametric magnetic resonance imaging and/or elevations in prostate specific antigen density (>0.2 ng/ml/cc) prompted biopsies throughout the protocol period of 3 years. 

Multiparametric MRI had a sensitivity of 57% (95% CI 39%-74%), specificity of 82% (95% CI 74%-89%), positive predictive value of 50% (95% CI 38%-62%) and negative predictive value of 86% (95% CI 81%-90%) for detecting progression to clinically serious prostate cancer. Multiparametric MRI had an odds ratio (OR) of 6.20 (95% CI 2.72-14.16, P<.001) for predicting progression, while prostate specific antigen density had an OR (OR) of 6.19 (95% CI 2.14-17.92, P=.001) for doing the same. Multiparametric MRIs with high-risk pathological characteristics (pT3 or high-volume International Society of Urological Pathology >2) were false-negative in just 2.3% (4/172) of patients. All patients in the group were followed for a median of 69 months (Q1-Q3 56-79), during which time 99.3% were free of biochemical recurrence, 100% were free of metastasis, and 100% were free of prostate cancer-related death. 

Based on the results of the Magnetic Resonance Imaging in an Active Surveillance trial, skipping the 1-year confirmatory biopsy during active surveillance poses minimal risk if a magnetic resonance-targeted + saturation template biopsy was performed at baseline. However, a standardized 3-year systematic biopsy should be performed due to the occasional magnetic resonance imaging-invisible tumors.