MP37-06 MULTIPARAMETRIC MAGNETIC RESONANCE IMAGING AND MRI/ULTRASOUND FUSION-GUIDED BIOPSY STRATIFY PATIENTS AT RISK FOR EXTRACAPSULAR EXTENSION AT RADICAL PROSTATECTOMY

Abstract

INTRODUCTION AND OBJECTIVES: In patients with prostate cancer (CaP), preoperative identification of extracapsular extension (ECE) can provide vital information for the surgical planning of robotassisted radical prostatectomy (RARP). Historically, MRI has had limited sensitivity for ECE. We aim to evaluate which parameters on multiparametric MRI (MP-MRI) and MRI/ultrasound (MRI/US) fusionguided biopsy aid in the pre-operative assessment of ECE. METHODS: Between May 2007 and August 2013, 299 patients at our institution underwent 3T MP-MRI, MRI/US fusion-guided biopsy with standard 12-core biopsy, and RARP. Visualized lesions were identified as low, moderate, or high suspicion for CaP according to the previously validated NIH scoring system. Findings were characterized as “presence of ECE,” “extracapsular bulge,” or neither. MP-MRI findings were correlated with biopsy results, final RARP pathology and margin status. Univariate analysis was performed to evaluate preoperative predictors of ECE on final pathology. RESULTS: MRI was positive for ECE in 27 patients and negative in 272, with a sensitivity of 17.2% and a specificity of 93.2% when compared to final pathology. In all patients, the rate of positive surgical margins was 15.1%. This rate increased to 22.2% in the subset of patients with MRIs that were positive for ECE, but increased to 31.1% in those patients whose MRIs were false negatives. In the group of patients with negative MRIs, PSA, MRI suspicion score, presence of bulge, and highest Gleason score on MRI/US fusion-guided biopsy were all associated with ECE on final pathology (p<0.001, Table). This was not the case for standard 12-core biopsy. CONCLUSIONS: When ECE is correctly identified on MRI, margin involvement increases slightly as compared to that seen with low risk CaP. However, margin involvement increases much more substantially when the final pathology report of ECE was unexpected due to a false negative MRI. In the absence of visible ECE on MP-MRI, the lesion suspicion score, presence of extracapsular bulge, and Gleason score on MRI/US fusion-guided biopsy can help identify those patients who are most likely to harbor ECE. This may guide pre-operative surgical planning and reduce the occurrence of positive surgical margins after RARP.