Predictors of positive surgical margins after laparoscopic robot assisted radical prostatectomy.

PURPOSE: We identified the predictors of positive surgical margins in a series of patients undergoing robot assisted laparoscopic radical prostatectomy.MATERIALS AND METHODS: We prospectively collected data from 322 patients who underwent robot assisted laparoscopic radical prostatectomy for clinically localized prostate cancer between April 2005 and October 2008, and who had not received any prior hormonal therapy.RESULTS: Positive surgical margins were observed in 95 cases (29.5%). Specifically positive surgical margins were at the apex in 22 cases (6.8%), anterior in 5 (1.6%) and posterolateral in 68 (21%). Among the preoperative variables prostate volume on transrectal ultrasound (HR 0.420, p = 0.002) and cT stage (HR 2.217, p = 0.008) were independent predictors of the presence of any positive surgical margin in the cohort while cT stage (HR 2.070, p = 0.025) and biopsy Gleason score (p = 0.019) were predictors of posterolateral positive surgical margins. Considering pathological variables only extraprostatic extension of the primary tumor was an independent predictor of any positive surgical margin (HR 11.852, p <0.001) and posterolateral positive surgical margins (HR 7.484, p <0.001) in the series. Of those patients with organ confined disease positive surgical margins were present in 21 (10.6%). Only perineural invasion was an independent predictor of any positive surgical margin (HR 4.096, p = 0.028) while a not statistically significant trend was identified with regard to posterolateral positive surgical margins (HR 6.938, p = 0.067).CONCLUSIONS: Pathological extension of the primary tumor was the most relevant predictor of positive surgical margins. In patients with organ confined disease the presence of perineural invasion was significantly associated with positive surgical margins.