Prostate Cancer Grading and Gleason Scores

If you or a family member is diagnosed with prostate cancer it is important to understand prostate cancer grading and Gleason scores. First, though, let's take a look at prostate cancer itself.

Hand removing tube in laboratory
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What Is Prostate Cancer?

Prostate cancer develops in the prostate — a small gland that makes seminal fluid. It is one of the most common types of cancer in men. Prostate cancer usually grows over time and in the beginning usually stays within the prostate gland, where it may not cause serious harm. While some types of prostate cancer grow slowly and may need minimal or no treatment, other types are aggressive and can spread quickly.

Prostate cancer that is caught early has a better chance of successful treatment.


Prostate cancer that is more advanced may cause signs and symptoms such as:

  • Trouble urinating
  • Decreased force in the stream of urine
  • Blood in the semen
  • Discomfort in the pelvic area
  • Bone pain
  • Erectile dysfunction

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 the cancer cells under a microscope to decide how abnormal the cancer cells are. The more abnormal they 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 cell 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 cancer and the better your prognosis.​

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  • 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.
  • Mayo Clinic, Prostate Cancer.

By Matthew Schmitz, MD
Matthew Schmitz, MD, is a professional radiologist who has worked extensively with prostate cancer patients and their families.