Grade Group 1 Core Volume at Time of Biopsy Is Not Associated With Rate of Adverse Pathology at Radical Prostatectomy

Purpose: To determine the association of grade group (GG) 1 core positivity with rates of adverse pathology in intermediate-risk prostate cancer, hypothesizing that inclusion of GG1 core positivity in National Comprehensive Cancer Network (NCCN)–based stratification is not associated with rates of adverse pathology at the time of surgery. We additionally explored use of targeted biopsy results from MRI-detected lesions in improving risk stratification. Methods: We included 307 fusion biopsy patients with intermediate risk disease who underwent radical prostatectomy. Modified intermediate-risk disease, as determined by biopsy, was defined using the same criteria as NCCN stratification, with the exception that GG1 positive cores were not counted as part of the core-positivity equation. We additionally evaluated a novel classification scheme based on MRI-visible presence of GG3 disease using data from targeted fusion biopsy. Results: Using current criteria, 144 patients (46.9%) had favorable risk disease, while 175 (57%) did with modified criteria, representing a change in 31 patients (19%). AUC for prediction of adverse pathology using traditional criteria was 0.552 and 0.551 using modified criteria ( P = .97). AUC for predicting adverse pathology when stratifying those men with GG3 disease and/or a total MRI-visible GG2 or GG3 tumor volume of 11.5 mm or higher as unfavorable had an AUC of 0.611 ( P = .048). Conclusions: Inclusion of GG1 core positivity in the determination of unfavorable disease stratification is not associated with rate of adverse pathology. Inclusion of MRI-visible tumor grade and volume data may improve risk stratification.