Prostate Cancer Grading and Gleason Scores
What Is Cancer “Grading”?
After a biopsy is taken and prostate cancer is diagnosed, the “grade” of your cancer will be determined. This is done by examining cells from the cancer under a microscope to decide how abnormal the cancer cells are.
The more abnormal the cancer cells are, the more likely the cancer is to be aggressive or to spread quickly outside of the prostate. The grade of your cancer is an important piece of information for your physicians to have when deciding upon the proper treatment.
The most common scale for prostate cancer grading is the Gleason score.
What Is the Gleason Score?
When cells from the prostate are examined under a microscope, the pathologist will identify many types of cells that range from very normal, non-aggressive cells to very abnormal, aggressive cells. The pathologist determines which type of cell is the most common and which type is the second most common.
Each of these two cell types is then given a score from 1 to 5. Higher numbers in this system mean more abnormal, aggressive cancer cells.
Because the two most common types of cancer cells are identified in the prostate, the Gleason score is a combination of these two cells types.
For example, if the most common cell type is a 3 (on the 1 to 5 scale) and the second most common type is a 4, then the Gleason score is reported as a 7 or sometimes as a “3+4”.
Similarly, if the most common cell type found is a 3 and the second most common type is a 2, then your Gleason score is a 5 or “3+2”.
For the most part, the lower your overall Gleason score is, the less aggressive the cancer and the better your prognosis.
Allsbrook Jr WC, Mangold KA, Yang X, et al. The Gleason grading system: an overview. J Urologic Path 10:141-157, 1999.
Gleason DF. Histology grading of prostate cancer: a perspective. Hum Path 23:273-279, 1992.