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.