The role of MRI-targeted and confirmatory biopsies for cancer upstaging at selection in patients considered for active surveillance for clinically low-risk prostate cancer.

PURPOSE: The purpose of this study was to assess the roles of MRI-targeted biopsies (TB) and confirmatory biopsies for cancer upstaging at selection in patients considered for active surveillance (AS) for low-risk prostate cancer (PCa) based on the first systematic biopsy (SB) series in another centre. METHODS: From 2009 to 2012, 41 patients with PCa diagnosed within the last 4 months and eligible for AS [clinical stage ≤T2a, prostate-specific antigen (PSA) <10 ng/ml, ≤2 positive biopsy cores with no Gleason pattern 4 or 5 and ≤5 mm involvement of any biopsy core] underwent pre-biopsy MRI, confirmatory transrectal ultrasound 12-core SB and MRI-TB of suspicious lesions. A contingency table assessed the accuracy of MRI to predict cancer upstaging. RESULTS: Median age and PSA were 63.5 years and 5.3 ng/ml, respectively. Overall, 24 patients (59 %) were upstaged. This upstaging was obtained at a confirmatory SB in 16 patients (39 %) based on the Gleason score (9), on cancer length (8) or both (7) and at MRI-TB in 17 patients (41 %) based on the Gleason score (14), cancer length (9) or both (6). Nine patients were upstaged at both SB and TB (22 %). The added value of MRI-TB was 20 % (8/41). The positive and negative predictive values of MRI for predicting cancer upstaging were 79 and 70.5 %, respectively. CONCLUSION: MRI-TB and confirmatory SB upstaged 59 % of cases, improving the selection of patients considered for AS at the first series of SB. Variation in histologic grade assignation between centres and better cancer sampling may explain this high upstaging rate.