The short answer
The Gleason score grades prostate cancer by how abnormal the cells look under a microscope. It adds two pattern numbers into a total from 6 to 10 — lower scores tend to grow slowly, higher scores more aggressively. It is one part of the full picture.
The Gleason score describes how prostate cancer cells look and how likely they are to grow.
It combines two pattern grades into a total, usually from 6 to 10.
Lower scores (like 6) tend to grow slowly; higher scores are more aggressive.
Reports may also list a Grade Group from 1 to 5, a newer way of expressing the same idea.
Choose how you want to understand this
The full explanation.
The short version
If you are reading a prostate biopsy report, the Gleason score is often the number that draws the eye. The Gleason score describes how prostate cancer cells look under a microscope and how likely they are to grow and spread. It is a measure of grade, not of how far the cancer has spread.
How the number is built
A pathologist looks at the sample and identifies the two most common cell patterns. Each pattern is graded from 3 to 5, based on how abnormal it looks. The two grades are added together, which is why a report might read "3 + 4 = 7." The order matters: the first number is the most common pattern in the sample, so a 3 + 4 tends to be viewed a little more favorably than a 4 + 3, even though both total 7.
Because each pattern grade starts at 3, the lowest total you will usually see is 6.
What the totals suggest
In general:
- 6 tends to be the least aggressive.
- 7 is intermediate.
- 8 to 10 tends to be more aggressive.
Many reports now also list a Grade Group from 1 to 5, a newer way of expressing the same idea. Grade Group 1 corresponds to Gleason 6; Grade Group 5 corresponds to Gleason 9 to 10.
It is one part of the picture
The Gleason score is important, but it is not the whole story. Care teams combine it with your PSA level, the stage of the cancer, your age, and your overall health to understand risk and plan next steps. For some lower-risk cancers, that plan may involve active surveillance rather than immediate treatment.
What to ask
Ask your care team what your Gleason score and Grade Group are, how they fit with your PSA and stage, and what options those results point toward. Their interpretation of the full report is what applies to you.
Words to know
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Common questions
▸What is a good Gleason score?
Lower is generally more favorable. Scores start at 6 because the two pattern grades that make up the total each start at 3. A score of 6 tends to be the least aggressive, while 8 to 10 tends to be more aggressive. Your care team interprets it alongside other results.
▸How is the Gleason score calculated?
A pathologist looks at the two most common cell patterns in the sample, grades each from 3 to 5, and adds them. So a report might read '3 + 4 = 7.' The order matters, because the first number is the most common pattern.
▸What is a Grade Group?
Grade Group is a newer scale from 1 to 5 that maps to Gleason scores. Grade Group 1 is the least aggressive (Gleason 6), and Grade Group 5 is the most aggressive (Gleason 9 to 10). Many reports now list both.
▸Does a higher Gleason score mean I need treatment right away?
Not automatically. The score is one factor. Care teams weigh it with PSA level, stage, your age, and overall health to plan next steps, which for some lower-risk cancers may include active surveillance.
Questions to ask your doctor
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Your next step
Plain-language definitions for the words on your report.
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