Objectives: To examine whether the percentage of core biopsies positive can further stratify Gleason score 7 patients with primary Gleason grade into precise prognostic groups.
Methods: Between 1991 and 1999, 379 radical prostatectomy patients were found to have pathologic Gleason 7 tumors. The patients were divided into primary grade 3 or 4. Percentage positive was calculated by dividing the number of positive core biopsies by the total number of cores.
Results: In the cohort, 290 tumors were primary grade 3, and 89 were primary grade 4. On univariate analysis patients with primary grade 3 tumors had a significant prostate-specific antigen (PSA) progression-free survival advantage over grade 4 patients. When separated according to percentage of core biopsies positive, statistical analysis revealed significantly better 60-month actuarial PSA progression-free survival for patients with grade 3 and grade 4 and less than 50% core biopsies positive as compared with grade 3 and grade 4 and 50% or more core biopsies positive (85%, 85%, 61%, and 33%, respectively). Furthermore, multivariate analysis demonstrated that primary grade did not have an independent impact on biochemical progression-free survival. However, on subset analysis, among patients with 50% or more biopsy cores positive, primary Gleason grade was indeed found to have a significant, independent impact.
Conclusions: In the present study Gleason 7 patients with primary grade 4 tumors and less than 50% of biopsy cores positive had an excellent prognosis after radical prostatectomy. Our data suggest that among Gleason 7 patients, the percentage of positive biopsies is a stronger predictor of biochemical progression-free survival than primary Gleason grade.