MP56-17 SYSTEMATIC BIOPSY IS UNNECESSARY FOR MEN WITH PIRADS 5 AND PSA DENSITY GREATER THAN 15%

Abstract

INTRODUCTION AND OBJECTIVE: To evaluate the detection of clinically significant prostate cancer (CSPCa) by systematic (SB) and target biopsy (TB) in men with Prostate Imaging Reporting and Data System - PIRADS 5; and the need for SB in this population. METHODS: We identified consecutive patients with PIRADS 5 lesion on multiparametric MRI (mpMRI; 3T, T2W, DWI, ADC, DCE) undergoing prostate biopsy (PBx) for suspicion of PCa, from our PBx database (IRB# HS-13–00663). Patients underwent mpMRI followed by 12-core SB and at least two TB cores per PIRADS 5 lesion. All MRIs were re-reviewed by an experienced radiologist. PBx were performed by an expert urologist using an MRI-transrectal ultrasound fusion system (Koelis). Each core-biopsy was labeled individually and interpreted according to ISUP Grade Group (GG) standards. Men with prior treatment for PCa or poor-quality MRI were excluded. The positive predictive value (PPV) of PIRADS 5 on MRI for CSPCa (GG ≥2) detection on PBx was analyzed. PSA density (PSAD) was calculated by dividing PSA by prostate volume on MRI. RESULTS: A total of 124 patients met inclusion criteria. The median (IQR) age, PSAD, number of positive cores, cancer core length and percent were: 69Y (64-75), 0.23ng/ml/cc (0.13-0.36), 7 (5-9), 12mm (9-15) and 90% (70-95), respectively. The CSPCa detection rate for SB+TB, TB and SB was: 88%, 82% and 65%, respectively. SB added 6% CSPCa detection to TB. The PPV for SB + TB of PIRADS 5 for any GG PCa and for CSPCa was 95% and 88%. Only 6 (6/124 = 5%) patients were not diagnosed with PCa on PBx: 2 with granuloma, 2 HGPIN, 1 focal inflammation, 1 benign prostatic tissue, but with metastatic PCa on pelvic lymph node biopsy. Considering only patients with PSAD>0.15ng/ml/cc (N = 86; 68% of the entire cohort), the CSPCa detection rate for SB+TB, TB and SB was: 95%, 92% and 72%. SB added 3% CSPCa detection to TB. Three (3/86=3.5%) patients with PSAD>0.15ng/ml/cc were diagnosed with CSPCa only on SB, and GG 1 PCa on TB. Had they been diagnosed with GG 1 on TB alone; these patients would not meet criteria for active surveillance because of high PSA or large cancer volume. The PPV for SB + TB of PIRADS 5 for any GG PCa and for CSPCa in men with PSAD>0.15ng/ml/cc was 98% and 95%, respectively. CONCLUSIONS: PIRADS 5 on mpMRI showed high positive predictive value for CSPCa on prostate biopsy. In those with PSAD>0.15ng/ml/cc, systematic biopsy marginally increased CSPCa, but not overall PCa detection in comparison to target biopsy alone. Systematic biopsy didn’t affect patients’ management and could be omitted on this population. Source of Funding: This study was funded in part by the R01 grant CA205058-01 from the National Institutes of Health/ National Cancer Institute (M.C.S, I.S.G. and A.L.A.).