Exploring positive surgical margins after minimally invasive radical prostatectomy: Does body habitus really make a...

Positive surgical margins (PSMs) at radical prostatectomy (RP) are generally recognized as a surrogate of poor or difficult dissection of the prostatic gland. In open RP cohorts, obesity seems to be associated to an increased risk of PSMs, probably due to the technical challenge that obese men pose to surgical access. Minimally invasive RP has been claimed to possibly reduce PSM rate. Aim of the study was to explore the impact of obesity and body habitus on PSM risk and their localisation during laparoscopic and robotic-assisted RP.

We reviewed 539 prospectively enrolled patients undergoing laparoscopic and robotic-assisted RP with pT2 prostate cancer. The outcome measured was rate of PSM according to the BMI and surgical approach (laparoscopic vs robotic-assisted). Patients were categorized in BMI<25kg/m², BMI 25-29.9kg/m² and BMI >30kg/m² groups respectively and compared using Kruskall-Wallis or χ² test, as appropriate. Uni- and multivariate logistic regression models were constructed to assess the impact of BMI and surgical technique on PSM risk.

Overall, 127 (24%) of men had PSMs detected at final specimen evaluation. Mean PSM length was 3.9±3.4mm, and 30 (6%) men presented significant margins ≥4mm. Analysing the rate of PSMs across BMI categories, no significant association between increased BMI and PSM was detected (all P>0.48). On uni- and multivariate logistic regression BMI was not a statistically significant risk factor for PSM (P=0.14), nor was the minimally invasive technique (laparoscopic vs robotic-assisted) (P=0.54).

In this study obese men do not appear to have a significant increase in risk of PSMs at RP compared to lean and overweight men when operated by a minimally invasive approach. The magnified vision and increased access to the pelvis allowed by a laparoscopic and robotic-assisted approach may be accountable for our findings. Larger studies are needed to validate our results.

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