Should Gleason score 7 prostate cancer be considered a unique grade category?

Abstract

Objectives. To evaluate pathologic characteristics and biochemical survival rate differences between patients with Gleason score 6 or less, 7, and 8 or more prostate cancer. Methods. A total of 652 patients who underwent a radical prostatectomy for clinically localized prostate cancer between March 1991 and December 1995 were selected for this study. Patients who underwent neoadjuvant or adjuvant hormonal therapy or radiotherapy were excluded. Clinical and pathologic data were obtained from our prostate cancer data base. Serum prostate-specific antigen (PSA) level, pathologic stage, and disease-free survival (DFS) were analyzed between the three Gleason score groups. Results. The overall mean pretreatment serum PSA level was 12.9 ng/mL, being 8.4, 13.4, and 23 ng/mL for Gleason score 6 or less, 7, and 8 or more prostate cancers, respectively ( P = 0.0001). Of patients with specimen Gleason score 6 or less, 7, and 8 or more, pathologic organ-confined disease was present in 69.4%, 43.1%, and 9.2%, respectively ( P = 0.001). Extraprostatic extension was present in 30.6%, 56.9%, and 90.8% ( P = 0.0001); positive surgical margins, considered independently from the other pathologic findings, were present in 31%, 47.6%, and 67.8% of patients with Gleason score 6 or less, 7, and 8 or more, respectively ( P = 0.0001). DFS was 34.5% for patients with Gleason score 8 or more, 75% for Gleason score 7, and 91.2% for Gleason score 6 or less prostate cancers, at a median follow-up of 34.2 months ( P = 0.0001). On multivariable analysis, after adjusting for serum PSA level (10 or less or more than 10 ng/mL) and pathologic stage, Gleason score (6 or less, 7, 8 or more) remained a statistically significant predictor of DFS ( P = 0.0001). Conclusions. Patients with Gleason score 7 prostate cancer should be considered a specific prognostic category. We believe that this distinction is critical to obtain more reliable results from prostate cancer analyses about prognosis of patients treated with curative intent.