Introduction: The Precise study, a prospective randomized trial, demonstrated that MRI with only targeted biopsy was non-inferior to systematic TRUS guided biopsies in the detection of GG =2 PCa. An unanswered question is the outcome in those patients who avoided a biopsy due to a negative MRI. We addressed the outcome of patients on this trial who were unbiopsied, or had a negative or GG1 targeted biopsy, compared to those whose systematic biopsy was negative or GG1, with respect to the rate of subsequent prostate cancer diagnosis based on a 2 year MRI performed in all patients. In addition, we used administrative provincial data to compare the net costs of systematic biopsy vs MRI and targeted biopsy. Methods: The study was carried out at 5 Canadian centres. The Precise trial accrued 453 biopsy-naïve men with a clinical suspicion of PCa advised to have a prostate biopsy. All those not initially diagnosed with GG=2 PCa (unbiopsied due to a negative MRI, or a negative biopsy, or GG1 disease if biopsied) were entered in the follow up study. All Ontario patients were entered in the economic analysis. The intervention was an MRI at year 2 in all men in both MRI and systematic biopsy groups. Biopsy was performed for PiRads = 3 or clinical suspicion. Results: 73 patients in the MRI arm and 69 patients in the systematic biopsy arm had a 2 year evaluable MRI. In the MRI and syst bx arm, 70% and 72% had a negative 2 year MRI. Of the 16 patients in the systematic biopsy arm who had a 2 year biopsy, 8 were negative, 2 were GG1, and 6 were GG =2. In the MRI arm, 8 were biopsied; 4 were negative, and 4 were GG =2. At 2 years, in the Syst Bx and MRI groups, 27% and 30% either were diagnosed with GG=2. disease; treated, died, or progressed. 15% from the TRUS biopsy group had a hospital visit after biopsy compared to less 6% from the MRI+ group. The mean per person per year (PPPY) costs for the TRUS and All MRI groups (MRI- and MRI+) were $7,828 and $8,525, respectively. Conclusions: After 2 years of follow up including an MRI in all patients, there was no difference in the rate of CS Pca diagnosis between the MRI with only targeted biopsy and systematic biopsy groups, despite 40% of men in the MRI group avoiding biopsy. These patients will be followed for an additional 6 years to confirm this finding. Economic analysis using a linked provincial databased demonstrated no significant difference in net cost between the 2 strategies. This data reinforces that an imaging first diagnostic strategy is safe and cost-effective. ClinicalTrials.gov Identifier: NCT02936258 SOURCE OF Funding: This study was co-funded by the OICR, and Prostate Cancer Canada.
