The lowest score is (3+3), and the highest is (5+5). For example, a score of (3+5) means that there were two different grades of cancer in that specimen on that spot on the prostate. The first number on the score, i.e. (3+5), means that Gleason 3 was found, and Gleason 5 cancer was also found. But there were fewer Gleason 5 cells than Gleason 3 (thus it is placed second in the parentheses). Because a biopsy samples tissue from several locations on your prostate, you can have a (3+4) and a (4+3) on different specimens from the same biopsy.
These numbers add up to a total score. Gleason 3+5=8 means your Gleason score (combined Gleason grades) is 8. Your score will help to determine if you need further imaging studies, such as a bone scan. A bone scan will show if the cancer has spread beyond your pelvis. Dr. Rich Bevan-Thomas also uses the prostate MRI routinely as this is the most helpful imaging study to evaluate whether the cancer has spread outside of the prostate or potentially into the local lymph nodes.
Your Gleason score also determines your risk category according to National Comprehensive Cancer Network (NCCN) guidelines.
- A score of 6 is low-risk.
- A score of 7 means intermediate-risk.
- A score of 8, 9, or 10 is considered high-risk.
From here, Gleason scores have grade groups which differentiate the risk between the different numbers. So a Gleason score 7 (4+3) is in a higher-grade group than a Gleason 7 (3+4) because there are more higher-grade cells in the (4+3) sample, and those cells have a higher risk of growing faster and beyond the prostate.