The impact of the 2005 International Society of Urological Pathology consensus conference on standard Gleason grading of prostatic carcinoma in needle biopsies

Purpose: At an International Society of Urological Pathology consensus conference in 2005 the Gleason grading system for prostatic carcinoma underwent its first major revision. We compared the concordance of pattern and change of prognostic groups for the conventional and the modified Gleason grading, and checked the discriminative power of the modified Gleason grading. Materials and Methods: The grading was based on 172 prostatic needle biopsies of patients subsequently undergoing radical prostatectomy. Four prognostic Gleason grading groups were considered, divided into scores of 2-4, 5-6, 7 and 8-10. To check the discriminative power of the modified Gleason grading we compared the time of biochemical (prostate specific antigen) progression-free outcome according to prognostic groups between standard and revised grading. Results: The greatest impact of the International Society of Urological Pathology consensus recommendations for Gleason grading was seen on the secondary pattern which had the lowest percentage of concordance and was reflected in a change toward higher Gleason prognostic groups. Of 172 patients in whom the Gleason prognostic group was changed (to higher grades) based solely on the consensus criteria, 46 (26.7%) had higher preoperative prostate specific antigen, more extensive tumors and positive surgical margins, and higher pathological stage. The revised Gleason grading identified in this series a higher number of patients in the aggressive prognostic group Gleason score 8-10 who had a significantly shorter time to biochemical progression-free outcome after radical prostatectomy (log rank p = 0.011). Conclusions: The findings of this study indicate that the recommendations of the International Society of Urological Pathology are a valuable refinement of the standard Gleason grading system.