Modified Gleason grading. An updated review

Abstract

At an ISUP (International Society of Urological Pathology) consensus conference in 2005 in San Antonio, Texas, the old Gleason grading system for prostatic carcinoma from 1966 underwent its first major revision. With this modified Grading system a shift of the most frequent Gleason scores from 6 to 7a (3+4) in biopsy specimens and an increased degree of agreement between specimens of biopsies and radical prostatectomies with carcinoma of the prostate could be demonstrated. After modified grading of GS 3+4=7a tumours 95% were stage pT2, while 79% of GS 4+3=7b tumours were stage pT3-4. In cases with PSA <10 ng/ml and tumour extent <20% the most frequent Gleason scores were 6 and 7a. Cases with serum PSA >10 ng/ml or tumour extent >20% had higher scores (7b or higher). Cancers with tumour infiltration of <1mm in one of 12 cores and PSA <10 ng/ml were mainly low grade (Gleason scores 6 and 7a) and may correspond to so called insignificant carcinoma of the prostate.

Conclusion: With the modified Gleason system, grade, stage, tumour extent and serum PSA show good correlations and characterize the difference between low and high grade malignancy of prostate carcinoma.