Purpose: Available published studies evaluating the association between nerve sparing robot-assisted radical prostatectomy and risk of ipsilateral positive surgical margins were subject to selection bias. In this study we overcome these limitations by using multivariable regression analysis.
Materials and methods: Patients undergoing robot-assisted radical prostatectomy for prostate cancer at 4 institutions from 2013 to 2018 were included in the study. 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.
Results: A total of 5,148 prostate lobes derived from 2,574 patients who underwent robot-assisted radical prostatectomy were analyzed. Multivariable analysis showed nerve sparing was an independent predictor for ipsilateral positive margins (OR 1.42, 95% CI 1.14-1.82). Other significant predictors for positive margins were prostate specific antigen density (OR 3.64, 95% CI 2.36-5.90) and side specific covariates including highest preoperative ISUP (International Society of Urological Pathology) biopsy grade (OR 1.58, 95% CI 1.13-2.53; OR 1.62, 95% CI 1.13-2.69; OR 2.11, 95% CI 1.39-3.59 and OR 4.43, 95% CI 3.17-10.12 for ISUP grade 2, 3, 4 and 5, respectively), presence of extraprostatic extension on magnetic resonance imaging (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).
Conclusions: Nerve sparing was associated with an increased risk of ipsilateral positive surgical margins. The increased risk of positive margins should be considered when counseling patients who opt for nerve sparing robot-assisted radical prostatectomy.
Keywords: margins of excision; outcomes; prostatectomy; prostatic neoplasms.