Tumor Grade at Margins of Resection in Radical Prostatectomy Specimens Is an Independent Predictor of Prognosis

ObjectivesTo 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.MethodsWe 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.ResultsThe 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.ConclusionsThis 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).