The Gleason score describes how aggressive a prostate cancer is.
If cancer cells are found during your biopsy, the pathologist will use a method known as the Gleason system to describe (or grade) the two types of tissue that make up most of the tumor based on how similar or different it looks compared to normal, healthy prostate tissue.
A number ranging from 3 (looks similar to normal tissue) to 5 (looks very abnormal) is assigned to each of the two patterns the pathologist sees. The two numbers are then added together to produce a total Gleason score between 6 and 10. The higher the number, the more aggressive the cancer is likely to be.
The Gleason scores are organized into Grade groups which help make it easier to understand.
Gleason patterns | Gleason score | Grade Group | Risk | Prognosis |
---|---|---|---|---|
3+3 | 6 | 1 | Low risk | Low-grade cancer is less aggressive and likely to grow and spread very slowly. If the cancer is small, many years may pass before it becomes a problem. Low-grade cancer may never need treatment. |
3+4 | 7 | 2 | Low to intermediate risk | Intermediate-grade cancer is moderately aggressive and likely to grow and spread at a modest pace. If the cancer is small, several years may pass before it becomes a problem. To prevent problems, treatment may be needed. |
4+3 | 7 | 3 | Intermediate risk | |
4+4, 3+5, 5+3 | 8 | 4 | High risk | High-grade cancer is very aggressive and likely to grow and spread quickly. If the cancer is small, a few years may pass before the cancer becomes a life-threatening problem. To prevent problems, treatment is needed now. |
4+5, 5+4, 5+5 | 9 or 10 | 5 | Very high risk |