Site specific predictors of positive margins at radical prostatectomy: An argument for risk based modification of technique

Purpose: We identify patients at high risk for positive bladder neck, apical or posterior margins who may benefit from technical modifications, such as excision of the bladder neck or wide excision of the neurovascular bundles. Materials and Methods: We studied 242 patients with clinically localized prostate cancer undergoing radical prostatectomy with or without neoadjuvant androgen deprivation therapy between June 1992 and August 1997 who had a sextant biopsy available for review. Multivariate logistic regression analysis was used to develop models for prediction of positive bladder neck, apical, and right and left posterior margins based on clinical parameters. From these models patients at low and high risk for positive margins were identified. Results: The incidence of positive margins was 36% with 69% solitary sites. Patients with a prostate specific antigen of greater than 10 ng./ml. had a higher incidence (16%) of positive bladder neck margins. Patients with 3 or more positive cores who did not receive neoadjuvant androgen deprivation therapy had a higher incidence (24%) of positive apical margins. A nomogram incorporating pretreatment serum prostate specific antigen, number of ipsilateral positive cores and whether androgen deprivation therapy was used identified patients at high risk for positive posterior margins. Conclusions: The nomograms presented identify patients at high risk for positive margins at various sites who may benefit from modification of surgical technique based on risk.