Positive surgical margins and early oncological outcomes of robotic versus open radical prostatectomy at a medium case-load institution

Background: The aim of this study was to analyze the rates of positive surgical margins (PSM) after radical prostatectomy in patients undergoing robotic surgery (robot assisted laparoscopic prostatectomy [RALP]) compared with those undergoing open surgery (radical retropubic prostatectomy [RRP]), at an institution with medium case load. Methods: Retrospective consultation of a perspectively-maintained database that stores the data of all the patients submitted to radical prostatectomy at our institution since 1/2008. The indication to RRP vs. RALP was based almost exclusively on the period of the study: RRP was the sole available option between 1/2008 and 3/2010 and afterwards RALP become the standard of treatment, once a learning curve of 50 cases was concluded. A PSM was defined as the presence of cancer at the inked surface of prostate. Aunivariate and multivariate binary logistic regression estimated which factors were related to PSMs. Results: The data of 576 patients (285 RRP, 291 RALP) were evaluated. The overall PSM rate was 28.1% (162/414 patients; 20.6% for pT2 stage, 51.8% for pT>2); overall PSM rate for RRP vs. RALP was 31.9% vs. 24.4 % (P=0.044). At multivariable analysis the factors related to the risk of PSM were stage pT>2 (RR2.979, P=0.001), Gleason Score >6 (RR1.662, P=0.026), the volume of tumor (RR1.019, P=0.008) and the surgical technique (RALP vs. RRP, RR0.647, P=0.039). Conclusions: In a series from a medium case-load institution, once data are adjusted for local staging, tumor volume and Gleason score, the risk of PSM is lower for RALP than RRP. This evidence could be of support for health-care practitioners to introduce robotic systems.