Understanding Grade Groups
What Are Grade Groups?
Grade Groups are a newer, simplified way of describing prostate cancer aggressiveness. They were introduced in 2014 by Dr. Jonathan Epstein and adopted by the World Health Organization in 2016.
Grade Groups run from 1 to 5 and directly correspond to Gleason scores. They were created to address a key problem with the Gleason system: because Gleason scores in practice range from 6 to 10, patients with a score of 6 often assumed they were 'in the middle' — when in fact Gleason 6 is the lowest-risk category.
Why Were Grade Groups Created?
The Grade Group system was designed to:
- Start at 1 (not 6), making it immediately clear that Grade Group 1 is the lowest risk.
- Separate the two types of Gleason 7 (3+4 vs. 4+3), which have meaningfully different prognoses.
- Provide a cleaner, more intuitive scale for patients and clinicians alike.
- Better predict outcomes based on large datasets of patient follow-up.
Grade Group to Gleason Score Conversion
| Grade Group | Gleason Score | Description |
|---|---|---|
| Grade Group 1 | Gleason 3+3=6 | Lowest risk — cells look relatively normal |
| Grade Group 2 | Gleason 3+4=7 | Favorable intermediate — mostly grade 3 with some grade 4 |
| Grade Group 3 | Gleason 4+3=7 | Unfavorable intermediate — mostly grade 4 with some grade 3 |
| Grade Group 4 | Gleason 4+4=8 (or 3+5 / 5+3) | High risk — predominantly grade 4 or higher |
| Grade Group 5 | Gleason 9–10 | Highest risk — most aggressive appearance |
If your report says Grade Group 1 (Gleason 3+3=6), your cancer is considered low-grade. Many men with Grade Group 1 cancer are candidates for active surveillance rather than immediate treatment.
What Each Grade Group Means
Grade Group 1 (Gleason 3+3=6)
Cells look relatively similar to normal prostate tissue. Very low risk of spread. Active surveillance is often appropriate.
Grade Group 2 (Gleason 3+4=7)
Mostly grade 3 cells with some grade 4. Favorable intermediate risk. Treatment is often recommended, though active surveillance may be considered in select cases.
Grade Group 3 (Gleason 4+3=7)
Mostly grade 4 cells with some grade 3. Unfavorable intermediate risk. Treatment is generally recommended.
Grade Group 4 (Gleason 4+4=8 or 3+5=8 or 5+3=8)
High-grade cancer. Cells look quite different from normal. Treatment is strongly recommended.
Grade Group 5 (Gleason 9–10)
The most aggressive pattern. Cells look very abnormal. Prompt treatment is typically recommended.
Grade Group is one important piece of your risk assessment, but it is considered alongside your PSA level, clinical stage, number of positive cores, and other findings. Your overall risk category (low, intermediate, high) is determined by combining all of these factors.
Many patients see Grade Group 3, 4, or 5 and immediately assume the worst. Remember that these numbers describe how the cancer cells look under the microscope—they do not predict your future by themselves.
Your doctor considers many pieces of information together, including your PSA, MRI findings, biopsy results, Stage, Grade Group, genomic testing (if performed), age, overall health, and your personal goals before recommending treatment.
Rather than focusing on the number alone, ask your healthcare team:
"How does my Grade Group fit into my overall diagnosis and treatment plan?"
That conversation is far more valuable than trying to interpret a single number on your own.