Gleason Grade Group Concordance between Preoperative Targeted Biopsy and Radical Prostatectomy Histopathologic Analysis: A Comparison Between In-Bore MRI-guided and MRI-Transrectal US Fusion Prostate Biopsies

PURPOSE: To determine and compare rates of grade group (GG) discrepancies between different targeted biopsy techniques (in-bore vs fusion) after propensity score weighting using whole-mount radical prostatectomy (RP) histopathologic analysis as the reference standard. MATERIALS AND METHODS: This retrospective study evaluated men who underwent targeted (fusion or in-bore) biopsy between April 2017 and January 2019 followed by prostatectomy. The primary endpoint of the study was a change in GG from biopsy to RP at a patient level. For downgrade and upgrade analysis, men with biopsy GG1 (downgrade not possible) and GG5 (upgrade not possible) were excluded, respectively. GG upgrade, downgrade, and concordance rates of each targeting approach were compared using propensity score weighting and logistic regression with inverse probability of treatment weighting. Significance level was set at .05. Index lesion GG on RP specimen served as the reference standard. RESULTS: A total of 191 men (90 in the in-bore [mean age, 63 years ± 7 (standard deviation)] and 101 in the fusion biopsy group [mean age, 65 years ± 7]) were eligible and included. Fewer GG upgrades were noted in the in-bore biopsy group (14%; 12 of 85) compared with the fusion plus systematic biopsy group (30%; 28 of 93) (P = .012). The incidence of GG downgrade in the in-bore group (25%; 21 of 84) was higher than in the fusion group (17%; 16 of 93); however, the difference was not statistically significant (P = .2). Of the 77 men misclassified by both biopsy techniques, the majority (56%, n = 43) had a change in GG of 2 to 3 or 3 to 2. CONCLUSION: Superior sampling accuracy with MRI-guided in-bore biopsies offers a lower incidence of GG upgrades compared with MRI–transrectal US fusion biopsies upon RP. Keywords: Biopsy/Needle Aspiration, MR-Imaging, Oncology, Pathology, Prostate Supplemental material is available for this article. © RSNA, 2021