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Understanding Your Gleason Score: Prostate Cancer Grade

One important element of determining the stage of prostate cancer is understanding the grade. For prostate cancer patients, the grade is defined using the Gleason score. The score itself can give your doctor an idea of whether or not the cancer will be slow-growing or more aggressive. The lower the grade, the earlier the stage of prostate cancer. To do that, cells from various parts of the prostate need to be examined under a microscope. After completing this evaluation the pathologist will assign a Gleason score. That score is used to determine the Grade Group which impacts the treatment plan that will be recommended.

What is a Gleason Score?

Prostate cancer doesn't always have the same grade throughout the entire impacted area. That’s why cells are examined from more than one area. Based on what is seen under the microscope you can be given two grades, known as primary and secondary grades, each one representing a different area of the prostate. Each area is assigned a number 1 through 5. For example, if most of your cancer is grade 3 and a smaller amount is grade 4, your Gleason score is listed as 3+4=7. The first number (the primary grade) in the Gleason score means that most of the cancer cells are that grade.

The Gleason score is based on the aggressiveness of prostate cancer. Essentially, the lower the number of your Score, the closer to normal the cell tissue is. A lower score also indicates that the cancer is likely to be slow-growing. Keep in mind, if you score less than a six, then it is not considered cancer.

Based on the Gleason score you’ll be assigned a grade group.


  • Grade group 1: Gleason score of 6 or less.


  • Grade group 2: Gleason score of 3+4=7.

  • Grade group 3: Gleason score of 4+3=7.


  • Grade group 4: Gleason score of 8.

  • Grade group 5: Gleason score of 9 to 10

What is the Meaning of Different Gleason Scores?

The higher the Gleason score, the more aggressive the cancer and the more likely it is to spread. Here's a more thorough breakdown of what your score means:

  • Low Grade: Gleason Score = 6 or less: This number indicates that most likely, the cancer will be slow-growing and not very aggressive. Typically, patients with this level of Score have the best treatment outcomes. In some cases treatment is not recommended for low grade prostate cancer patients and watchful waiting is implemented.

  • 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 would 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 is more likely to grow quickly and spread. Prognosis for an 8 is definitely better than a 10, but treatment will be recommended right away.

The Importance of the Gleason Score

It's important to understand the Gleason score because studies indicate that it correlates closely with the behavior of the cancer cells in your body. The score itself can give your doctor an idea of whether or not the cancer will be slow-growing or more aggressive.

While the Gleason score can tell your oncologist a lot about the behavior of your cancer and what type of treatment plans may be best, it is not the only method used to understand your cancer. Other factors about your cancer can also help paint the entire picture. Other points to consider include:

  • PSA blood test score

  • Physical exam outcomes

  • Imaging results

  • Whether cancer was found on both sides of the prostate

  • Whether cancer has spread outside the prostate

Your oncologist can provide more information about what these particular points mean for your cancer diagnosis and treatment plan.

Chicagoland’s Experts in Prostate Cancer Treatment and Research

The prostate cancer specialists at Affiliated Oncology understand that those facing a prostate cancer diagnosis are likely to have many questions about what’s right for them. We are here to ensure that you completely understand your diagnosis and what you can expect from treatment when the timing is right for prostate cancer treatment. Schedule a consultation with one of our oncologists in Chicago Ridge, Mokena, Hazel Crest, Palos Heights, or Oak Lawn, IL to discuss your next steps.