MP16-18 OPTIMAL COMBINATION OF MRI-TARGETED BIOPSY AND SYSTEMATIC BIOPSY FOR MEN WITH SUSPICION OF PROSTATE CANCER

Abstract

INTRODUCTION AND OBJECTIVES: Magnetic resonance imaging (MRI)-targeted prostate biopsy (MRBX) is an effective biopsy procedure for with suspicion of prostate cancer on MRI. However, some significant cancer (SC) is missed using MRBX. Use of systematic prostate biopsy (SBX) for negative areas on MRI to detect SC missed by MRBX is not established for this indication. In this study, we aimed to explore the optimal combination of SBX and MRBX in these patients. METHODS: Between 2014 and 2015 at our institution, 271 men underwent MRBX with or without SBX based on prebiopsy multiparametric 1.5T MRI. Of these, 52 were excluded from the analysis because of PSA levels>40 ng/ml, obvious clinical T3-4 disease or biopsy with an insufficient number of cores for severe comorbidity. The remaining 219 men who underwentMRBXandSBXinonesessionaccording toourbiopsyprotocolwere enrolled in this study. MRBX was performed under cognitive or MRI/transrectal ultrasound fusion. Using MRBX, four-core samples for one suspicious lesiononMRIwereperformed.TheSBXprotocolwasa transperineal18-core biopsy.SCwasdefinedasclinical stageT2borgreater,biopsyGleasonscore of 4+3orgreater, ormaximumcancer lengthof 5mmorgreater.Cancerother thanSCwasdefinedas indolent cancer (IC). SC thatwasnot detected or that wasdetectedas ICusingMRBX,but thatwasdetectedasSCusingSBXwas defined as MRBX-missed SC. The frequency of MRBX-missed SC was investigated. A SBX protocol that could sufficiently detect MRBX-missed SC with a minimum number of sampling cores was determined. RESULTS: The median PSA was 7.5 ng/ml, and one/two suspicious lesions were observed in 204/15 patients, respectively, using MRI. The detection rate of any cancer or SC using both MRBX and SBX was 76%or 61%, respectively. Frequency ofMRBX-missed SC to overall SC was 13% (21/135). MRBX results in MRBX-missed SC patients was no cancer in 8 and IC in 13. Of 21 MRBX-missed cancer, a maximum of 10, 13, 15, 17, 19, 20 and 21MRBX-missed SCwere detected using 2, 4, 6, 8, 10, 12and14SBXsamplingcores, respectively.Whenweset theSC detection rate using both MRBX and the transperineal 18-core SBX at 100%, aminimum of 6 sampling cores in SBX (in addition to MRBX) were required to detect 95% of overall SC as SC. The six SBX sampling locationswere bilateral transperineal anterior, posterior and far lateral sites. CONCLUSIONS: The combination of transperineal 6-core SBX and MRBX could be an optimal biopsy strategy that strikes a balance between SC detectability and sampling number for men with suspicion of prostate cancer on MRI.