The Gleason score describes the grade of prostate cancer. Areas of cells in prostate cancer biopsies are graded on a scale from 1 to 5. 1 is the lowest grade, and the cells look most like normal cells. 5 is the highest grade and the cells look more abnormal. The scores from two areas with the highest grade cells are added together to give the Gleason score. So the score can be as low as 2 or as high as 10.