What does your Gleason score measure?
Gleason score describes what prostate cells from a biopsy look like under a microscope.
The Gleason score is not a measure of how big the cancer is or how far it has spread. It is a way pathologists describe how prostate cells look under a microscope compared with normal prostate tissue. That’s it. The more the cancer cells resemble normal cells, the lower the score. The more distorted and disorganized they appear, the higher the score. 1 to 10.
The Gleason score is made up of two numbers. The first number represents the most common pattern seen in the biopsy. The second number represents the next most common pattern. These two numbers are added together to create the Gleason score.
This is why you’ll hear numbers like 3+3, 3+4, or 4+3. Even though the total may be the same, the order matters. A 3+4 behaves differently than a 4+3, because in one example the dominant pattern is 3 and in the other, the dominant patter is 4.
It may surprise you to know that a Gleason score of 6 (written as 3+3) is considered low-grade cancer (this is out of 10). Under the microscope, these cells still look fairly similar to normal prostate tissue and tend to grow very slowly. Many men with Gleason 6 disease never need immediate treatment and can be safely monitored through active surveillance.
Gleason 7 falls into a middle category. A 3+4 generally behaves less aggressively than a 4+3, even though both add up to 7. Gleason scores of 8, 9, or 10 indicate higher-grade disease that looks much less like normal prostate tissue and typically requires more active treatment.
You may also hear your doctor refer to Grade Groups and this makes things a bit more confusing. This is a newer, simplified system that ranges from Grade Group 1 (Gleason 6) to Grade Group 5 (Gleason 9–10). The goal is to make risk easier to understand.
The Gleason score is one piece of the puzzle, not the whole picture. PSA trends, imaging, tumor volume and overall health all contribute. And don’t discount the effect of genetics in this equation. Two men with the same Gleason score may make very different and equally reasonable, treatment decisions.
When you understand what these numbers mean, you can shift the conversation from “How bad is this?” to “What are my options, and what makes sense for me?” I hope this helps.
The Monday Brief highlights existing information that I feel is important enough to share with you, as well as explanations and discussions about topics I receive the most questions about.
Recently a dear friend called me to ask about Gleason score for his brother. Another asked about her father’s Gleason score. Then, just this week I met with a dentist who wanted to understand Gleason score better.
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