Understanding Prostate Cancer: Gleason Score, Grade Groups, and Risk Stratification
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Gleason Scoring System
When you have a prostate biopsy, a pathologist (a doctor who studies tissue samples) looks at your cells under a microscope. They use the Gleason scoring system to measure how aggressive your cancer may be.
How Does Scoring Work?
The pathologist gives two scores based on what they see in your sample. Think of it this way — your pathologist is looking at your cells and sorting what they see:
- The first score reflects what they see the most.
- The second score reflects what they see the second most.
Each score ranges from 3 to 5. A score of 3 means the cells still look similar to normal prostate cells. A score of 5 means the cells look very different. The two scores are added together to give your combined Gleason score. For example, a first score of 3 added to a second score of 4 gives a combined Gleason score of 7 (3+4=7). Combined scores range from 6 to 10.
Grade Group System
| Grade Group | Gleason Score | What It Means |
|---|---|---|
| Grade Group 1 | 3+3=6 | Low risk, less aggressive |
| Grade Group 2 | 3+4=7 | Intermediate risk, more favorable |
| Grade Group 3 | 4+3=7 | Intermediate risk, more favorable |
| Grade Group 4 | 4+4=8 | High risk, more aggressive |
| Grade Group 5 | 9-10 | Very high risk, more aggressive |
How Will My Score Guide My Treatment?
Your doctor will use your Gleason score and Grade Group — along with other factors — to determine your level of risk. This process is called risk stratification. It is a way of grouping cancers by how likely they are to grow or spread, so your doctor can recommend the best treatment for you.
The factors used in risk stratification include your PSA (Prostate-Specific Antigen) levels, the size and extent of your tumor (called the T-stage), and how many biopsy samples tested positive. Together, these factors place your cancer into one of the following risk categories:
- Low Risk — Gleason score 6 or below (Grade Group 1), PSA under 10 ng/mL, T-stage T1–T2a. For some people in this group, your doctor may suggest active surveillance. This means watching the cancer closely over time rather than treating it right away.
- Intermediate Risk — Gleason score 7 (Grade Groups 2 and 3), PSA 10–20 ng/mL, T-stage T2b. This category includes “favorable” and “unfavorable” subcategories that help fine-tune your treatment approach.
- High Risk — Gleason score 8–10 (Grade Groups 4 and 5), PSA above 20 ng/mL, T-stage T2c–T3a. At this level, your doctor will likely recommend more immediate treatment, such as surgery or radiation.
- Very High Risk and Metastatic — Advanced stages (T3b–T4) or cancer that has spread to other parts of the body. Your care team will work with you to develop a comprehensive plan suited to where things stand.
You and your doctor will use this information together — along with your personal preferences and goals — to find the treatment plan that is right for you.