Apical Surgical Margins Status in Robot-Assisted Laparoscopic Radical Prostatectomy Does Not Depend on Disease Characteristics

Background and Purpose: Positive surgical margins (PSM) during robot-assisted laparoscopic radical prostatectomy (RALP) are generally considered an adverse event. We attempted to identify the factors associated with PSM and their location. Patients and Methods: Records of patients undergoing RALP between 2003 and 2009 were retrospectively reviewed. We collected demographic (age, race, body mass index [BMI]), cumulative surgical experience (years from RALP introduction at our center), clinical (prostate-specific antigen [PSA] levels, and biopsy Gleason sums), nerve-sparing technique (yes/no), and pathological variables, including stage (organ-confined vs. non), Gleason sums, prostate weight, status, and location of the surgical margins. Multivariate regression models were constructed to identify the factors associated with PSM at prostate apex, periphery, proximal, and all locations. Results: A total of 560 patients were analyzed. Median age was 60.1 (interquartile range [IQR] 55.1-64.7), 19% were African-Americans, median BMI was 28.1 (25.8-30.8 kg/m(2)), PSA levels were 5.3 (3.9-7.1 ng/mL), and prostate weight was 45.2 (36.8-57.0 g). Gleason sums were as follows: <= 6 in 42.5%, 7 in 53.4%, and >7 in 3.1%. Overall, PSM were reported in 130 (23.2%), including 58 (44.6%) apical, 81 (62.3%) peripheral, and 20 (15.4%) proximal. The overall rate of PSM was associated with surgical experience, PSA, prostate weight, and Gleason sums. Apical PSM were independently associated only with surgical experience. Peripheral PSM were associated with PSA, stage, Gleason sums, and prostate weight. Finally, proximal margin status showed an association with PSA levels only. Conclusions: While peripheral, proximal, and overall PSM are largely associated with inherent disease biology (grade, PSA levels, etc.), apical margin status is independently associated only with cumulative surgical experience. These results suggest that a lower rates of positive apical margins may be obtained as the cumulative center experience grows, suggesting a potential role of a "teaching learning curve," independently from disease characteristics.