Number of positive systematic sextant biopsies predicts surgical margin status at radical prostatectomy

To determine whether the number of positive sextant biopsies contributes to the prediction of positive surgical margins, as the value of systematic prostate biopsies in predicting margin status at radical prostatectomy is unclear.

Consecutive patients (n = 108) who underwent radical retropubic prostatectomy and systematic sextant biopsies were retrospectively evaluated. Serum prostate-specific antigen, digital rectal examination, primary Gleason grade, Gleason score, and the number and location of positive sextant biopsies were recorded for each patient. Radical prostatectomy specimens were evaluated by step-section techniques at 3 to 5-mm intervals. Univariate comparisons for each of these variables was performed between the positive and negative margin groups using the Mann-Whitney U test or chi-square analysis. Logistic regression analysis was performed for these variables.

Twenty-two (20.4%) of 108 patients had a positive surgical margin because of extension of the tumor through the capsule. Patients with three or more positive biopsies were at higher risk of having a positive surgical margin (P = 0.009). Patients with bilaterally positive biopsies at either the base or midprostate were more likely to have a positive surgical margin. The risk of a positive surgical margin was not significantly determined by the primary Gleason grade, Gleason score, or prostate-specific antigen. Multivariate logistic regression models were created that consistently demonstrate that the number of positive biopsies was the best predictor of margin status.

This study demonstrated that the number of positive sextant biopsies contributes to the prediction of margin status at radical prostatectomy.