The Gleason score is one of the pieces of information doctors use in staging a patient's prostate cancer. It helps them to determine how far the cancer has spread and the aggressiveness of treatment it requires, according to WebMD. Regardless of the treatment, the initial score serves as a baseline.
In order to assign a Gleason score, a pathologist studies the cells from the biopsy under a microscope, explains WebMD. He ranks them on a scale of 2 to 10. Cells most like normal cells receive a rating of 2, and the cells with the most deformity receive a score of 10. The scores of the two most common types of cells in the sample add together to provide the total score. Scores of 8 or higher indicate aggressive cancers.
Prostate cancer includes a wide spectrum of diseases, indicates WebMD. Because there are so many variables that define the disease, doctors use staging to describe the amount of cancer and its spread. Stage I cancers affect less than 5 percent of the tissue. Stage IV cancer spreads beyond the prostate and affects other organs.
No matter what treatment plan the patient and doctor choose, the patient undergoes further testing in the future. The tests include more biopsies for Gleason scores, prostate-specific antigen tests, and exams. The doctor compares the results of these tests with the initial tests to determine if the cancer returns, spreads or progresses, explains WebMD.