The Gleason grading system for prostate cancer (PCA) was developed in the 1960s by DF Gleason. Due to changes in PCA detection and treatment, the application of the Gleason grading system has changed considerably in pathology routine practice. Two consensus conferences were held in 2005 and in 2014 to update PCA Gleason grading. This review provides a summary of the changes in the grading of PCA from the original Gleason grading system to the prognostic grade grouping, as well as a discussion of the clinical significance of the percentage of Gleason patterns 4 and 5.
