Trends in distribution and prognostic significance of Gleason grades on radical retropubic prostatectomy specimens between 1989 and 2001

BACKGROUND. The objectives of the current study were to examine time trends in the prevalence of Gleason grades of prostate cancer on radical retropubic prostatectomy (RRP) specimens and to assess the resultant impact on prognosis. METHODS. The authors examined the prevalence over time of each grade and Gleason score (GS) on RRP specimens from 8750 patients who were treated between 1989 and 2001. Biochemical recurrence-free survival (BRFS), which was estimated by using Kaplan-Meier methodology, was examined in subgroups of patients defined by tumor grade and era of surgery. RESULTS. The prevalence of Grade 3 prostate cancers increased (86% vs. 49% for primary Gleason grade and 71% vs. 47% for secondary Gleason grade; 1999-2001 vs. 1989-1990, respectively), whereas the prevalence of Grade 2 tumors decreased (0.4% vs. 38% for primary Gleason grade and 1.3% vs. 28% for secondary Gleason grade, respectively) over the study period, leading to fewer GS 4 and 5 tumors and more GS 6 and 7 tumors. BRFS improved over time for patients who had GS 5 tumors (hazards ratio [HR], 0.92 per year; P = .003) and GS 6 tumors (HR, 0.93; P<.001) but remained unchanged for GS 7 tumors (HR 0.99; P = .462) and GS 8-10 tumors (HR 1.02; P = .360). Patients who were treated in the recent era (1997-2001) had greater differentiation of BRFS based on GS or Gleason grade compared with patients who were treated earlier (1989-1991). CONCLUSIONS. The current results confirmed that there were changes in the prevalence of Gleason grades on RRP specimens between 1989 and 2001. A chronological change in pathologic grading classification is suggested by evolving prognostic implications, which must be accounted for when comparing outcomes from different eras.