Comparison of the rate, location and size of positive surgical margins after laparoscopic and robot-assisted laparoscopic radical prostatectomy.

OBJECTIVE To review and compare the rate, location and size of positive surgical margins (PSMs) after pure laparoscopic radical prostatectomy (LRP) and robot-assisted laparoscopic radical prostatectomy (RALP). PATIENTS AND METHODS The study comprised 200 patients who underwent RALP and 200 patients who underwent LRP up to January 2008. We compared patient age, body mass index, preoperative prostate-specific antigen (PSA), preoperative stage and grade, prostate size, pathological stage and grade and neurovascular bundle preservation, as well as PSM rate, size and location. Continuous and categorical data were compared using Student's t-test and Pearson's chi-squared test. Multivariate regression analyses were used to identify preoperative and intraoperative predictors of PSMs. RESULTS Although the PSM rate was similar between the two groups (LRP: 12% vs RALP: 13.5%; P = 0.76), location and size were not. PSMs after LRP were mostly at the apex (58.3%; P = 0.038), while most PSMs after RALP were posterolateral ([PL] 48%; P = 0.046). In addition, the median margin size after RALP was significantly smaller than after LRP (RALP: 2 mm vs LRP: 3.5 mm; P = 0.041). In univariate and multivariate analyses, tumour-node-metastasis (TNM) stage and preoperative PSA were the only independent preoperative predictors of PSMs (P = 0.044 and P = 0.01, respectively). CONCLUSION The PSM risk is dependent on TNM stage and preoperative PSA and not the surgical technique, when comparing LRP with RALP.