Importance of margin extent as a predictor of outcome after adjuvant radiotherapy for Gleason score 7 pT3N0 prostate cancer

Abstract

Purpose To evaluate, in Gleason score 7, pT3N0 prostate cancer patients with positive surgical margins, the predictors of progression-free survival and to identify a patient subgroup that would benefit from immediate adjuvant postoperative radiotherapy (ART). Methods and materials Between November 1989 and August 1998, 76 men underwent radical prostatectomy and were found to have capsular penetration (pT3N0), surgical Gleason score 7, tumor present at the resection margin, and an undetectable postoperative prostate-specific antigen (PSA) level. All surgical specimens underwent whole-mount serial sectioning to determine the degree of margin positivity (focal vs. extensive). Of the 76 men, 45 underwent early ART (within 6 months with a median dose of 64.8 Gy), and 31 had no immediate treatment. We defined freedom from PSA failure (bNED) as the absence of two consecutive PSA rises >0.2 ng/mL. Results The median follow-up time was 5.1 years (range, 2–10 years). The ART and non-ART patients were similar with respect to preoperative PSA level, Gleason score (4 + 3 vs. 3 + 4), presence of seminal vesicle invasion, and margin extent. On univariate analysis, margin extent was predictive for improved bNED (5-year bNED rate of 92% vs. 58%, p = 0.010, for men with focal and extensive margins, respectively). Gleason score (4 + 3 vs. 3 + 4), seminal vesicle invasion, and ART were not statistically significant predictors. On multivariate analysis, the preoperative PSA level, margin extent, and ART were independent significant factors. In the group with extensive surgical margins, men receiving ART had a significantly greater 5-year bNED survival rate compared with the non-ART patients (73% vs. 31%, p = 0.004). Conclusion These data suggest that the amount of microscopic residual tumor significantly affects bNED after radical prostatectomy for Gleason score 7, pT3N0 prostate cancer. In addition, men with pathologic evidence of microscopic local disease appear to benefit from early ART compared with untreated controls.