Understanding the Prostate Biopsy Gleason Score

Categories: Prostate Cancer

June 21, 2020

If you’ve received a prostate cancer diagnosis, the first thing your doctor may discuss with you is the Gleason Score. This is used to describe your stage of prostate cancer. Here we will review prostate cancer, the purpose of the Gleason Score, how it is calculated, and why it is so important.  

What is Prostate Cancer?

Prostate cancer is when cancer is found in the prostate, which is a gland in the male reproductive system. The prostate has two main duties in the body. The first is to secrete prostate fluid (which includes semen), and the second is to use muscles to move the seminal fluid into the urethra during ejaculation. The prostate gland is about the size of a walnut in younger males, but it can become much larger as they age. 

Prostate cancer occurs when the cells in the prostate gland begin to grow quickly and out of control. Normal prostate cells grow slowly and stay within the prostate.

There are five types of prostate cancers:

  • Adenocarcinomas
  • Small cell carcinomas 
  • Sarcomas 
  • Neuroendocrine tumors
  • Transitional cell carcinomas

Out of these five types, the most common is adenocarcinoma, which starts in the gland cells. 

For all types of cancer, a stage rating is given during diagnosis. This means oncologists will assign a grade that explains how aggressive the cancer is. When an oncologist stages prostate cancer, the Gleason Score is the method used to give that grade. 

What is the Gleason Score?

The Gleason Score is the grading method that is used to determine how aggressive a patient’s prostate cancer is. It was first developed by Donald Gleason in the 1960s. Prostate cancer is comprised of cancerous cells with different grades in most cases. Because of this, each patient is assigned two different grades: the first, referring to the most dominant grade of cancer cells and the second, referring to the second most common dominant grade of cancer cells found during the biopsy. 

How Does Gleason Scoring Work?

To confirm a suspicion of prostate cancer, your doctor will likely perform a prostate biopsy to confirm the diagnosis and gain insight into its characteristics. The Gleason Score ranges from 1-5 and describes how much the cancer from your biopsy looks like healthy tissue (lower score) or abnormal tissue (higher score). The two most dominant grades of cancer cells are each given a score that falls within that range. 

For example, a patient may be assigned a 3 and a 4. These two numbers are added together to determine the Gleason Score, which ranges from 2-10. Rarely do oncologists assign a Gleason Score below 6. Therefore, if we go back to our example, 3 and 4 would be added together for a sum of 7. This means 7 would be the patient’s Gleason Score. 

What Do the Different Gleason Scores Mean?

The Gleason Score is based on how aggressive the patient’s prostate cancer is. The lower the number, the closer to normal the cell tissue is. Lower scores mean the cancer is more likely to be slow-growing. Anything less than 6 is considered not to be cancer. 

On the other hand, a higher number means the cancer is more aggressive and more likely to spread. Here’s a breakdown of what the different scores mean:

  • Low Grade: Gleason Score = 6: This indicates that more than likely the cancer will be slow-growing and not very aggressive. Patients with these scores have the best prognosis.
  • Intermediate Grade: Gleason Score = 7: A score of 7 means that the patient has a 50/50 chance of having aggressive prostate cancer. If the patient received a primary grade of 3 and a secondary grade of 4, more than likely the cancer will grow slowly. However, if those numbers are reversed and the primary grade was 4 and the secondary 3, the cancer may be aggressive. 
  • High Grade: Gleason Score = 8-10: A score of 8-10 means the cancer is aggressive and likely to grow and spread at a fast pace.  

Why is the Gleason Score Important?

A study conducted by the University of Geneva states that the Gleason score relates very closely with the clinical behavior of the prostate cancer cells. For this reason, it is a very important indicator of how the cancer will act — slow-growing versus aggressive. 

While the Gleason Score isn’t the only tool used to determine whether you need to move ahead with treatment, it is one that can tell oncologists a great deal about the characteristics of prostate cancer. Other factors that are used and evaluated as a whole can include: 

  • Physical examination findings
  • Imaging test results 
  • PSA blood test score 
  • If cancer was found on both sides of the prostate
  • If cancer has spread outside the prostate

Virginia’s Leader in Prostate Cancer Treatment & Research

At Virginia Oncology Associates, we understand that those facing a prostate cancer diagnosis are fighters — and that’s why our staff consists of compassionate caregivers to help you through every step of the way. Rest assured, choosing VOA means that you are receiving the highest quality prostate cancer care available from our experienced clinicians. Contact us today for more information

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