Definition: A tumor grading procedure used to judge how aggressive a tumor will be. During the Gleason scoring process, the pathologist takes the numbers for the two most representative types of cells seen in the sample and adds them together. Two representative cell types seen in the tumor are rated with a number from 1=normal to 5=very abnormal. Then each of the numbers are added together to give a Gleason score.
Gleason scores will range from two to 10, with two being completely normal, and 10 very aggressive cancer. Generally Gleason scores of seven or above indicate a more serious prognosis with the chance that your tumors will be quite aggressive and spread quickly unless brought under control.