Accuracy of Sampling PI-RADS 4-5 Index Lesions Alone by MRI-guided In-bore Biopsy in Biopsy-naive Patients Undergoing Radical Prostatectomy

Background: Targeting multiparametric magnetic resonance imaging (MP-MRI)-suspicious regions alone in biopsy-naive patients is not common practice, since it may miss clinically significant prostate cancer (PCa). Objective: To investigate the accuracy of in-bore MRI-guided biopsy of Prostate Imaging Reporting and Data System (PI-RADS) 4 and 5 index lesions alone in biopsy-naive patients undergoing radical prostatectomy (RP). Design, setting and participants: A total of 170 patients underwent MRI-guided in-bore biopsy for PI-RADS 4 and 5 index lesions alone between 2013 and 2018, of whom 136 patients were diagnosed with PCa. Fifty-two patients without prior biopsy who underwent RP were included in this study. MP-MRI findings, biopsy results, and whole-mount step-section specimen evaluation were retrospectively analyzed. Outcome measurements and statistical analysis: Continuous variables were reported as mean (standard deviation) or median (range). Differences in parametric variables were calculated by Student t test. Results and limitations: Overall International Society of Urological Pathology grade group (GG) up- and downgrading rates were 23.0% and 7.6% per patient and 24.5% and 6.5% per focus, respectively. Ten of 12 biopsy-detected GG 1 foci were upgraded in the final pathology. In 30 patients, a total of 43 different tumor foci were identified outside the sampled index lesion. Average biopsied and nonbiopsied tumor volumes were found to be 2.02 and 0.45 cm(3), respectively (p < 0.001). The index lesion was the largest focus of tumor in all patients' final histopathological examination; upgrading was identified in only one nonbiopsied focus in a single patient. Limitations include retrospective design and nonstandard indications of in-bore MRI biopsy. Conclusions: In-bore MRI-guided biopsy of PI-RADS 4-5 index lesions alone in biopsy-naive patients is a safe and accurate diagnostic modality allowing appropriate patient selection for individualized treatment. Patient summary: In-bore magnetic resonance imaging-guided prostate biopsy of suspicious lesions alone allows accurate risk stratification of patients and reduces the detection of insignificant prostate cancer. (C) 2019 European Association of Urology. Published by Elsevier B.V. All rights reserved.