title: Risk factors associated with positive surgical margins following radical prostatectomy for clinically localized prostate cancer: can nerve-sparing surgery increase the risk?
abstract: OBJECTIVE
  The aim of this study was to evaluate the impact of preoperative and surgical parameters, including nerve-sparing technique, on the risk of positive surgical margins (PSM) following radical prostatectomy for clinically localized prostate cancer.
  
  
  METHODS
  A prospective consecutive single-institution Danish cohort of 1148 patients undergoing RP between 1995 and 2011 was investigated. To analyse the impact of covariates on risk of PSM, a multivariate logistic regression model was used, including cT category, biopsy Gleason score, prostate-specific antigen (PSA), percentage positive biopsies for cancer (PPB), surgeon and surgical technique.
  
  
  RESULTS
  The overall rate of PSM was 31.4%. The risk of PSM depended (p value for Wald χ(2)) on PSA (p < 0.0001), PPB (p = 0.003), nerve-sparing surgery (p = 0.03) and the surgeon (p < 0.0001). For every doubling of PSA, the risk of PSM increased by 56%, beginning at 0.5 ng/ml [odds ratio (OR) = 1.56, 95% confidence interval (CI) 1.3-1.9, p < 0.01], and every 10% increase in PPB resulted in an 11% increased risk of PSM (OR = 1.11, 95% CI 1.0-1.2, p = 0.002). Two out of the six surgeons had a 50% reduction of risk of PSM compared to the referent surgeon. Nerve-sparing surgery increased the risk of PSM by 50% compared to wide resection (OR = 1.5, 95% CI 1.0-2.1, p = 0.03).
  
  
  CONCLUSIONS
  Both preoperative and surgical parameters affect the risk of PSM after radical prostatectomy. Surgeon and high preoperative PSA, PPB and cT category were confirmed as predictors of PSM. Surprisingly, nerve-sparing surgery was independently associated with increased risk of PSM. The correct selection of candidates for nerve-sparing surgery remains unresolved.
authors.affiliation: Urology Research Unit, Department of Urology.
authors.forename: Martin Andreas
authors.initials: MA
authors.lastname: Røder
authors.forename: Frederik Birkebæk
authors.initials: FB
authors.lastname: Thomsen
authors.forename: Ib Jarle
authors.initials: IJ
authors.lastname: Christensen
authors.forename: Birgitte Grønkær
authors.initials: BG
authors.lastname: Toft
authors.forename: Klaus
authors.initials: K
authors.lastname: Brasso
authors.forename: Ben
authors.initials: B
authors.lastname: Vainer
authors.forename: Peter
authors.initials: P
authors.lastname: Iversen
mesh_terms: D006801:Humans; D008297:Male; D059351:Organ Sparing Treatments; D011446:Prospective Studies; D011467:Prostate / Q000294:innervation* / Q000601:surgery*; D011468:Prostatectomy / Q000379:methods; D011471:Prostatic Neoplasms / Q000473:pathology* / Q000601:surgery*; D018570:Risk Assessment; D012307:Risk Factors