Nerve-Sparing During Robot-Assisted Radical Prostatectomy Increases the Risk of Ipsilateral Positive Surgical Margins.
Available published studies evaluating the association between nerve-sparing robot-assisted radical prostatectomy (RARP) and risk of ipsilateral positive surgical margins were subject to selection bias. The aim of this study is to overcome these limitations by using multivariable regression analysis.Patients undergoing RARP for prostate cancer at four institutions from 2013 to 2018 were included. A multilevel logistic random intercept model, including covariates on patient level and side-specific factors on prostate lobe level, was used to evaluate the association between nerve-sparing and risk of ipsilateral positive margins.A total of 5,148 prostate lobes derived from 2,574 patients that underwent RARP were analyzed. Multivariable analysis showed nerve-sparing to be an independent predictor for ipsilateral positive margins (OR: 1.42, 95% CI: 1.14-1.82). Other significant predictors for positive margins were respectively PSAD (OR: 3.64, 95% CI 2.36-5.90) and side specific covariates including highest preoperative ISUP biopsy grade (ORs of 1.58 [95% CI 1.13-2.53], 1.62 [95% CI 1.13-2.69], 2.11 [95% CI 1.39- 3.59] and 4.43 [95% CI 3.17-10.12] for respectively ISUP grade 2, 3, 4 and 5), presence of extraprostatic extension on MRI (OR: 1.42, 95% CI 1.03-1.91) and percentage of positive cores on systematic biopsy (OR 3.82, 95% CI 2.50-5.86).Nerve-sparing was associated with an increased risk of ipsilateral positive surgical margins. The increased risk of positive margins should be taken into account when counselling patients that opt for nerve-sparing RARP.