Prostate Cancer Biopsy and Gleason Score

Differentiating the risk for growth in low-grade and intermediate-grade prostate cancers. For instance, studies have shown that people with Gleason score 3+4=7 do better than people with Gleason score 4+3=7, even though they have the same Gleason score and both have intermediate-grade cancers.

Researchers are currently working to develop artificial intelligence tools to help pathologists get more accurate, reliable, and consistent results when grading cancer cells. But none of these tools are available or used widely yet.

Because of some of these challenges, the International Society of Urological Pathology (ISUP) recommended some adjustments to the Gleason Scoring System in 2014. These adjustments allow your doctor to put your cancer into one of five Grade Groups based partly on your Gleason score. They also consider your PSA levels, PSA density, number of positive cores, and tumor stage. Grade Group 1 is the least likely to grow and spread, and Grade Group 5 is the most likely to grow and may spread quickly.

Based on Gleason score:

• Grade Group 1 includes Gleason scores of less than or equal to 6.
• Grade Group 2 includes Gleason score 3+4=7.
• Grade Group 3 includes Gleason score 4+3=7.
• Grade Group 4 includes Gleason score 8.
• Grade Group 5 includes Gleason scores 9-10.

Gleason Grading Scores

To determine your Gleason score, a pathologist will look at your prostate biopsy tissue under a microscope. They are looking to see what shape the cells are, how big they are, and what the internal structures look like. They do this because cancer cells change over time as they continue to grow and divide. They start out looking pretty much like healthy prostate cells, but as they continue dividing, they look less and less like healthy cells.

Your pathologist will look all around your biopsy tissue samples and grade each cell. They will assign a grade using a number from 1 to 5 to describe how much like healthy prostate cells your cells look to them.

The lower the Gleason number, the more like healthy cells they look; the higher the Gleason number, the less like healthy cells they look.

• Grade 1 includes cells that look very much like healthy prostate cells.
• Grades 2-4 include cells that look less and less like healthy cells as the number goes up. 
• Grade 5 includes cells that don't look anything like healthy prostate cells.

Almost all prostate cancer cells will have a grade of 3, 4, or 5.

After they have graded the cells, they divide the cells into two groups based on the patterns they see: the most common (primary) and the second most common (secondary) pattern. On your pathology report, you will see this written as an equation, like this: 3+4=7. From this, you can see that most of the cells were a grade 3 and most other cells were a grade 4, for an overall Gleason score of 7. If all the cells in the sample look the same, your number will be doubled, like this: 3+3=6.

Based on your Gleason score, your doctor may describe it as:

• For a Gleason score of 6 or less, well-differentiated or low-grade. In general, these tend to grow really slowly and are less likely to spread.
• For a Gleason score of 7, moderately differentiated or intermediate-grade. These tend to grow a little more quickly and may be more likely to spread.
• For a Gleason score of 8, 9, or 10, poorly differentiated or high-grade. These tend to grow more quickly and are more likely to spread.

Transrectal Ultrasound-Guided Biopsy

This is the standard way for your doctor to do a prostate biopsy. You will usually have it done in your urologist's office without sedation.

A transrectal ultrasound scan (TRUS) uses sound waves to make a picture of your prostate. Your doctor will place the ultrasound probe, which is about the width of your finger, in your rectum (butthole). With the picture of your prostate as a guide, your doctor will insert a thin, spring-loaded, hollow needle through the wall of your rectum and into your prostate gland. When your doctor removes the needle, they will remove a tiny cylinder of prostate tissue called a core.

Because prostate cancer is rarely only in one area of your prostate, your doctor will usually take an average of 12-15 cores of tissue from the different parts of your prostate. But they may take more samples if they think they need to. Your doctor will send all the core samples to a lab for your pathologist to look at.

It's possible to have different types of cancer in your prostate. Your lab report will tell your doctor where the pathologist found cancer cells, how much of each tissue sample contains cancer cells, and your Gleason score.

Why Is the Gleason Score Important?

Your Gleason score is an important part of how your doctor will assess how likely your cancer is to grow and spread. They'll consider your Gleason score along with other factors, like your PSA levels, your PSA levels over time, physical exam findings, and tumor imaging if you need it. They need to know how likely your cancer is to grow so that they can help you figure out what treatment path to choose.

For instance, some people who have low-grade cancer cells may not even need treatment. Your doctor may just be able to keep an eye on your PSA level. (This is called active surveillance.) As long as it stays around the same, your cancer cells likely aren't growing or spreading. This means you don't need surgery or radiation therapy that can cause side effects and impact your quality of life. On the other hand, if you have high-grade cancer cells, you may need surgery, radiation therapy, chemotherapy, and hormone therapy right away.

Takeaways

If you've had a prostate biopsy because your doctor suspects you have prostate cancer, a pathologist will use the Gleason Grading System to grade the cancer cells based on how much like healthy cells they look. They will then assign you a Gleason score. Your Gleason score is an important part of how your doctor will try to predict how likely your prostate cancer is to grow and spread. This helps them advise you on what treatment path to choose.

Gleason Score FAQs

What is a prostate cancer biopsy?

A biopsy is when your doctor removes a sample of tissue, cells, or fluid for a medical pathologist to look at under a microscope. By looking at your tissue under the microscope, they can see signs of disease, like an infection or cancer. There are a few ways to do a prostate cancer biopsy: transrectal, transperineal, and transurethral. The most common way is transrectal, which is when your doctor takes the biopsy samples through your rectum (butthole). Doctors usually use this way because they can take the biopsy without the need for a medicine to make you sleepy.

Transperineal is when your doctor takes the samples through the patch of skin between your rectum and scrotum. The least common way is transurethral, which is when your doctor takes the samples through your urethra (pee hole). You will usually need a medicine to make you sleepy if you have a transperineal or transurethral biopsy.

What are the treatment options for prostate cancer based on the Gleason score?

Deciding on a cancer treatment path can be complicated. Your doctor will advise you on your treatment options based on the stage of your cancer. Part of how they determine this is with your Gleason score, but that's only a part of how they determine your options. Check out Prostate Cancer Treatment Optionsto learn more about the different options.