The correlation analysis of positive surgical margin and biochemical recurrence after robot assisted laparoscopic radical prostatectomy

Objective To explore the influencing factors and correlation of positive surgical margin (PSM) and biochemical recurrence (BCR) in men after robot-assisted radical prostatectomy (RALP). Methods The clinical data of 190 patients with local or locally advanced prostate cancer who underwent RALP by single surgeon in the Department of Urology of Changhai Hospital from January 2016 to September 2017 were collected. Age was (67.5±6.9) years old; median body mass index (BMI), preoperative PSA, prostate weight were 24.2 kg/m2 (16.6-34.2 kg/m2), 15.0 ng/ml (1.41-393.94 ng/ml) and 36.9 g (8.65-207.58 g) respectively. The group of surgical margin was divided into negative surgical margin, apex-only PSM, base-only PSM as well as apex and base PSM. Characteristics between patients stratified by surgical margin or BCR were compared using χ2 test. The influencing factors of PSM were analyzed by logistic regression. Cox regression was used for the analysis of predictive factors of BCR. Log-rank test and Kaplan-Meier curves were used for comparing the BCR rate between the groups of surgical margin. Results Of all the 190 enrolled patients, total PSM rate was 24.7% (47/190), apex-only PSM rate was 13.2 % (25/190), base-only PSM rate was 5.8% (11/190), apex and base PSM rate was 5.8 % (11/190). Multivariate analysis showed the independent predictive factors influencing PSM were preoperative PSA (P=0.048) and pathological stage (P=0.004 ). The median follow-up period was 7.3 months (0.9-26.6 months) and BCR happened in 19.5% (37/190) patients. The rates of BCR were 15.4% (22/143), 16.0% (4/25), 27.3% (3/11) and 72.7% (8/11) in the patients with negative surgical margin, apex-only PSM, base-only PSM and both apex and base PSM respectively. Log-rank test revealed that the rate of BCR in patients with apex and base PSM was higher than that in patients with negative surgical margin (P<0.001) or patients with apex-only PSM(P=0.002). Cox analysis indicated that higher preoperative PSA (P=0.040), higher pathological stage (P=0.041) and higher pathological Gleason score (P=0.004) were the independent predictors of BCR. PSM was not a predictive factor of BCR (P=0.257). Conclusions Preoperative PSA and pathological stage are the influencing factors of PSM. Higher preoperative PSA, higher pathological stage and higher pathological Gleason Score are the predictive factors of BCR. PSM may not be a predictive factor of BCR. The relationship between PSM and BCR needs further study. Key words: Prostatic neoplasms; Radical prostatectomy; Robot; Positive surgical margin; Biochemical recurrence