The Gleason score
The Gleason score is used to help determine how quickly a tumor may grow or spread. It may seem confusing because with the Gleason system (the most common system used), there’s both a “grade” and a “score.”
The Gleason grade uses numbers 1 to 5. A number is assigned to two of the areas of the prostate that have the most cancer (based on biopsy core samples that are taken). This is because the cancer may look different in each of those two areas. Once those two numbers are determined, they are added together to come up with the Gleason score, which ranges from 2 to 10.
If the highest grade takes up 95% or more of a man's biopsy, however, that grade is counted twice as the Gleason score. If 3 grades of cancer are found in one biopsy core sample, the highest grade is always used, even if the majority of the core sample involves low-grade cancer.
The American Cancer Society reports that most biopsies are grade 3 or higher. Grades 1 and 2 are rarely used.
What the grades mean
- Grade 1: The cells look almost like normal cells (called well differentiated) and are uniformly spaced in a tight mass.
- Grade 2: The cancer cells are still well differentiated, but are arranged more loosely, are more irregular in shape, and some cells have spread to other prostatic tissue.
- Grade 3: The cancer is moderately differentiated; cells vary in size from small to large; and more cells have invaded other prostatic tissue.
- Grade 4: The cancer cells are irregular, distorted, and look less like normal cells (called poorly differentiated), and there is considerable spread (called invasion) to other prostatic tissue.
- Grade 5: The cancer cells do not look anything like normal cells and have spread in haphazard “clumps” of all different shapes and sizes through the prostate.
What the scores mean
- If your loved one’s score is less than 6, his cancer may be considered to be well-differentiated or low-grade
- A score of 7 may be considered to be moderately differentiated or intermediate-grade cancer
- A score of 8 to 10 may be considered to be poorly differentiated or high-grade cancer
According to the American Urological Association, the lowest Gleason score that is usually found after a biopsy is 5. The cancer is considered to be more aggressive as the score rises. Scores of 8 to 10 are considered to be the most aggressive, which means that the cancer is more likely to grow and spread more quickly.
Your loved one's biopsy results (called the pathology report) will contain other important information to help the doctor assess how aggressive his cancer may be. This includes:
- How many biopsy core samples were positive for cancer
- How much cancer was in each core sample (this is given as a percentage)
- Whether cancer was found in just one side of the prostate gland or in both sides (which is referred to as bilateral)
When the score may change
The initial score is based on a man’s biopsy results, which only includes several small samples taken from the prostate.
If your loved one decides to undergo
to have his prostate removed (called
the entire prostate gland can then be examined. So his score may change after surgery.
Always discuss everything you read on this web site with a qualified medical professional.
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American Urological Association. The Management of Localized Prostate Cancer. http://www.auanet.org. Accessed March 20, 2012.
The American Cancer Society. Prostate Cancer. http://www.cancer.org. Accessed March 20, 2012.
Walsh PC. Guide to Surviving Prostate Cancer. New York, NY: Time Warner Book Group; 2001.