Prognostic significance of location of positive margins in radical prostatectomy specimens

OBJECTIVES Cancer at the resection margin is associated with an increased risk of biochemical recurrence after radical prostatectomy (RP) even after adjusting for other known clinical and pathologic risk factors. In this study, we assessed the prognostic significance of sites of positive surgical margins (+SMs) in RP specimens. METHODS We reviewed the data from 2442 patients with clinical Stage T1-T3 prostate cancer treated with RP from 1983 to 2004 who had had tumor maps generated from whole mount sections. The site of +SMs was assigned to six different areas (apex, bladder neck, seminal vesicle, anterior, posterolateral, and posterior). RESULTS Of the 2442 patients, 201 (8.2%) had a +SM at a single site and 74 (3.0%) had a +SM at multiple sites in the RP specimen. The posterolaterat and apex sections were the most commonly involved sites for a +SM. Those with a +SM had a greater risk of biochemical recurrence than those with negative surgical margins (hazard ratio 1.39, 95% confidence interval 1.004 to 1.92; P = 0.047). We found that a +SM at the posterolateral site was significantly associated with an increased risk of biochemical recurrence (hazard ratio 2.80 for +SMs versus negative SMs at the posterolateral region; 95% confidence interval 1.76 to 4.44). CONCLUSIONS The effect on biochemical recurrence was influenced by the site of the +SM, with a posterolateral location having the most significant effect on prognosis. This heterogeneity of margin status has implications for predictive modeling, as well as the recommendation for adjuvant radiotherapy.