Role of preoperative positive apical biopsies in the prediction of specimen-confined prostate cancer after radical retropubic prostatectomy: A multi-institutional study

Objectives: A multi-institutional study of 280 radical prostatectomy specim ens obtained from three independent academic hospitals was undertaken to va lidate a nomogram developed for the prediction of specimenconfined prostate cancer after prostatectomy. Methods: Three preoperative factors - the Gleason score, prostatespecific a ntigen (PSA) and apical location of positive biopsies - that were identifie d with a previous logistic regression formula were collected. Links between margin status and preoperative criteria were confirmed by univariate metho ds. Subsequently, the predictive indexes of positive margins were calculate d and compared to the actual margin status in terms of predictive character istics. Results: This control series, independent of the initial series that was us ed to identify the relevant preoperative factors, confirmed that positive a pical biopsies(p<0.001), PSA (p<0.005) and the Gleason score (p<0.005) were strongly linked to the occurrence of positive margins. Different cutoff va lues for the predictive index were compared in a receiver operating charact eristic curve. A value of 0.5, similar to the one described in the original series, gave an adequate compromise between sensitivity and specificity wi th respective values of 68 and 73% and a test accuracy of 72%. In practical terms, it was possible to predict 85% of negative margins, and to delineat e two groups with different rates of positive margins (14.5 vs. 50%). Conclusions: We demonstrated that PSA, the Gleason score and apical biopsy status are cumulative risk factors for positive margins. Risk of positive m argins increases when it is not possible to obtain a wide excision of perip rostatic fascia, as at the apex. This study substantiates the independent p rognostic value of positive preoperative apical biopsies for predicting pos itive surgical margins. Copyright (C) 2000 S. Karger AG, Basel.