If you’re having tests for prostate cancer or recently received biopsy results, you may have heard your doctor mention a Gleason score. But what is a Gleason score, and what do those numbers mean?
A Gleason score describes how prostate cancer cells look under a microscope. It gives doctors an idea of how likely the cancer may be to grow and spread. The score usually comes from prostate tissue collected during a biopsy. It may also be reported after prostate surgery.
How Is a Gleason Score Calculated?
Prostate cancer can contain more than one pattern of cancer cells. A pathologist looks at the tissue under a microscope and grades these patterns based on how different they look from normal prostate tissue.
The patterns usually range from 3 to 5:
- Pattern 3: The cancer still forms recognizable glands.
- Pattern 4: The glands look more irregular and disrupted.
- Pattern 5: Normal gland formation has mostly disappeared.
The two main patterns are reported together. For example:
Gleason 3 + 4 = 7
The first number is usually the pattern that makes up most of the cancer. The second is the next most common pattern. The two numbers are added together to get the Gleason score.
Most prostate cancers today receive a Gleason score between 6 and 10. That can be confusing because a 6 may sound like it falls in the middle. But Gleason 6 is actually the lowest score typically given to prostate cancer.
In general:
- Gleason 6: Lower-grade cancer
- Gleason 7: Intermediate-grade cancer
- Gleason 8 to 10: Higher-grade cancer
Higher-grade cancers are more likely to grow and spread than lower-grade cancers.
Why Does the Order of the Gleason Numbers Matter?
Two prostate cancers can both have a Gleason score of 7 but still be different.
In Gleason 3 + 4 = 7, pattern 3 makes up most of the cancer, with a smaller amount of pattern 4.
In Gleason 4 + 3 = 7, pattern 4 makes up most of the cancer.
Pattern 4 is more abnormal than pattern 3. That means a 4 + 3 cancer generally has a higher risk of growing and spreading than a 3 + 4 cancer, even though both add up to 7.
This is also why they fall into different Grade Groups.
What Are Prostate Cancer Grade Groups?
Grade Groups are another way doctors describe prostate cancer. They range from 1 to 5:
- Grade Group 1: Gleason 3 + 3 = 6
- Grade Group 2: Gleason 3 + 4 = 7
- Grade Group 3: Gleason 4 + 3 = 7
- Grade Group 4: Gleason 8, including 4 + 4, 3 + 5 or 5 + 3
- Grade Group 5: Gleason 9 or 10
Grade Group 1 is the lowest grade, while Grade Group 5 is the highest.
Does the Gleason Score Tell You the Stage of Prostate Cancer?
Not by itself. Grade and stage tell you different things about prostate cancer.
Your Gleason score and Grade Group describe what the cancer looks like under a microscope and give doctors an idea of how it may behave.
A PSA level is also different from a Gleason score. PSA comes from a blood test, while a Gleason score comes from prostate tissue examined after a biopsy or surgery.
Cancer staging considers how far the cancer has grown or spread, along with other information about the cancer.
When planning your care, your doctor may also consider:
- Your PSA level
- Biopsy findings
- Imaging results
- Whether the cancer has spread
What Does Your Gleason Score Mean for Treatment?
Your Gleason score is an important part of treatment planning, but doctors don’t use it by itself.
Some men with Grade Group 1 prostate cancer may be able to choose active surveillance instead of starting treatment right away. Active surveillance may also be an option for some men with Grade Group 2 cancer.
Higher Grade Groups generally carry a greater risk of the cancer growing or spreading and may be more likely to require treatment. Your PSA level, cancer stage, age, overall health, and personal preferences can also affect your options.
Understand What Your Gleason Score Means
Knowing what a Gleason score is can make your prostate cancer results easier to understand. But the score is only one part of the picture.
Your urologist can explain your Gleason score, Grade Group, PSA level, and other results and what they mean for you.
If you have questions about prostate cancer testing, a recent diagnosis, or your treatment options, schedule an appointment with Atlantic Urology Clinics. Call 843.347.2450 to make an appointment in Myrtle Beach, Murrells Inlet, or Conway.