Tumor grade at margins of resection in radical prostatectomy specimens is an independent predictor of prognosis

Objectives: To assess whether reporting the grade of cancer at the site of positive margins in a radical prostatectomy (RP) specimen was independently prognostic of the outcome. Methods: We restricted our study to 108 patients with Gleason score (GS) 7, nonfocal extraprostatic extension (EPE) (Stage pT3a), and positive surgical margins. Patients with a tertiary pattern 5, those who had received neoadjuvant therapy, and those with positive margins because of an intraprostatic incision were excluded. Results: The overall GS was 3 + 4 in 73 patients (67%) and 4 + 3 in 35 (33%). The median length of the positive margin was 3.0 mm (range 0.5-10). The GS at the margin was 3 + 3, 3 + 4, 4 + 3, and 4 + 4 in 40 (37%), 41 (38%), 16 (14.8%), and 11 (10.2%) cases, respectively. Of the 108 patients, 45 (42%) remained free of disease after RP (median follow-up 6 years, range 3-13). Univariate and multivariate analyses showed no correlation between biochemical recurrence and either the preoperative serum prostate-specific antigen level (P = .7) or overall GS (P = .5). A strong association was noted between biochemical recurrence and the GS at the positive surgical margin (P = .007), with length of cancer at the margin also predictive (P = .015) on multivariate analysis. Using the median length of the positive margin (3 mm) as the cutoff, the association with biochemical recurrence was significantly different between the 2 groups (P = .004) using Kaplan-Meier analysis. Conclusions: This is the first study to show that the grade of cancer at the site of a positive margin influences the outcome. We were able to stratify the grade into 3 categories: 3 + 3, 3 + 4, and 4 + 3 or greater (4 + 3 and 4 + 4 at the positive margin provided equal prognostic information).