Role of core location in targeted MRI-ultrasound fusion biopsy of prostate lesions.

Abstract

136 Background: Targeted mpMRI fusion biopsy has gained adoption with superior clinically significant cancer detection rates and accuracy over template biopsy. We sought to establish the role of biopsy location within a prostate lesion to detect clinically significant prostate cancer. Methods: From Nov 2016-Aug 2017, 110 patients with positive multiparametric-MRI (mpMRI) underwent targeted and systematic MRI-US fusion biopsy at our institution for clinical suspicion or known history of prostate cancer. Lesions were scored by Prostate imaging reporting and data system (PI-RADS) classification schema by experienced genitourinary radiologists. Biopsy was performed by an oncology-trained urologist (PS) performing a high volume of fusion biopsies. 5 cores were taken from each lesion, each corresponding to a predetermined location (central, medial, lateral, apex, and base of the lesion). Cancer detection rates (CDR) were calculated on a per lesion basis from biopsy histology. Results: 154 prostate lesions were identified and biopsied with an average volume of 1.31 mL. Detection of clinically significant cancer (G>3+4) did not differ significantly among the 5 locations (Table 1). The central core detected slightly more G≥3+4 cancers than the apex core. No concordance of pathology grade was found between the central core and location of the peripheral core (medial, lateral, apex, or base). In 32% (50/154) of lesions, the peripheral cores had a higher Gleason score than the central core. Biopsy of only the central core missed 40% (21/52) of G≥3+4 cancers and 17% (4/24) of G>3+4 cancers. Lesions with higher PIRADs score were more likely to detect cancer in both the central and peripheral cores, but lesion volume was not a significant predictor. Conclusions: Location of biopsy cores within mpMRI-identified prostate lesions has little correlation with detection of clinically significant cancer. However, targeted biopsy of only the center of a lesion can miss 17% of Gleason >3+4 cancers. [Table: see text]