Positive Posterior Margin of Needle Biopsy Cores Is an Independent Predictor for Extracapsular Extension in Retropubic Radical Prostatectomy

Objective To introduce the new preoperative parameter as a predictor for extracapsular extension (ECE), we defined the presence of tumor at the stump of the rectum side on prostate needle biopsy as a positive posterior margin (PPM), and speculated that PPM is related to ECE. Methods This retrospective study was conducted in 230 patients who underwent prostate needle biopsy and retropubic radical prostatectomy between 2001 and 2011. We analyzed the association between their clinicopathological parameters and ECE. Results Multivariate analysis showed that the Gleason score ( P  = .023, odds ratio [OR] 1.433), serum prostate-specific antigen (PSA, P  = .013, OR 1.040), clinical stage ( P  = .018, OR 2.162), and PPM ( P  = .013, OR 2.253) were significant independent predictors for ECE. Next, using these 4 preoperative risk factors, we were able to accurately predict their ECE. Patients with 0 or 1 risk factor had a low probability of ECE (13.0% and 18.5%, respectively). In contrast, the majority of patients who had 3 or 4 risk factors were found to have ECE (80.1% and 71.4%, respectively). Conclusion The data suggest that the Gleason score, serum PSA, clinical stage, and PPM may be independent predictors for the existence of ECE. This suggests that the posterior margin in biopsy specimens is a more reliable and clinically useful parameter when making decisions concerning the choice of treatments.