Gleason grading of prostate cancer: level of concordance between pathologists at the University Hospital of the West Indies.

Our aim was to study the level of interobserver concordance in the Gleason scores of prostate needle biopsy specimens reported at 1 institution. A retrospective review of all prostate needle biopsy specimens in which a diagnosis of adenocarcinoma was made during the year 2000 was conducted. Parameters evaluated included the Gleason score, Gleason grades identified, the percentage of Gleason grades 4 and 5, and the percentage of tumor in the biopsy specimen. Our results demonstrated a 60% overall concordance in consensus Gleason scores, which increased to 80% when considered in groups of a Gleason score of less than 7 vs 7 or more. The greatest discordance seemed to be in distinguishing Gleason score 6 from 7 and was more frequent among biopsy specimens with lower tumor volumes, particularly among those with less than 30% involvement. A small percentage of Gleason grade 4 pattern might predict disagreement as well. Strategies for improving accuracy of Gleason score 7 should be devised, and consensus diagnosis for biopsy specimens that demonstrate a low percentage of tumor volume is recommended.