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Understanding the Gleason Scoring System for Prostate Cancer

Doctor with a clipboard reviewing a gleason score

If you’ve done any research regarding prostate cancer diagnosis and staging, you’ve likely come across what’s known as a “Gleason score.” Exactly what are Gleason scores, and what role do they play in the prostate cancer treatment process? Below, Moffitt Cancer Center explains what Gleason scores are, how they’re calculated, how to interpret them and how they differ from grade groups.

What is a Gleason score?

The Gleason scoring system was developed by Dr. Donald Gleason in the 1960s as a way to describe how prostate cancer cells behave on a microscopic level and how likely a malignancy is to grow and spread (metastasize). Today, a patient’s Gleason score is one of many factors that physicians consider when determining the most appropriate course of treatment. Other factors to be taken into account include how far a malignancy has already progressed as well as the patient’s:

  • Prostate-specific antigen (PSA) blood test results
  • Overall health
  • Treatment preferences

How is a Gleason score determined?

Dr. Gleason graded prostate cancer cells based on how closely they resembled normal cells. This ranged from Grade 1 (cancer cells that closely resembled healthy cells) to Grade 5 (cancer cells that had mutated so much that they barely resembled healthy cells anymore). After a patient had been diagnosed with prostate cancer, Dr. Gleason would analyze the two most common cell patterns in the patient’s tissue sample, assign each of them a grade and then combine those grades to come up with a total Gleason score.

In other words, to calculate a prostate cancer patient’s Gleason score, a pathologist must:

  1. Assign a grade to the most common cell pattern in the patient’s tissue sample (the primary pattern)
  2. Assign a grade to the second most common cell pattern in the patient’s tissue sample (the secondary pattern)
  3. Add the two grades together

For example, if a pathologist grades a prostate cancer patient’s primary cell pattern as a 3 and their secondary cell pattern as a 4, then the patient’s Gleason score would be a 7.

How to interpret a Gleason score

A high Gleason score suggests that prostate cancer is more likely to progress and spread to other areas of the body. A low Gleason score, on the other hand, suggests that a malignancy is growing more slowly.

Technically, Gleason scores can range from 2 to 10 (the lowest Gleason score of 2 would occur when a pathologist grades each cell pattern as a 1, and the highest Gleason score of 10 would occur when a pathologist grades each cell pattern as a 5). However, Gleason scores usually range from 6 to 10:

  • Gleason scores of 6 and lower indicate low-grade prostate cancer.
  • A Gleason score of 7 indicates intermediate- or medium-grade prostate cancer.
  • Gleason scores of 8 to 10 indicate high-grade prostate cancer.

Gleason scores vs. grade groups

In 2014, the International Society of Urological Pathology published an updated system for grading prostate cancer, commonly known as the “grade groups.” The system divides Gleason scores into five different groupings, ranging from Grade Group 1 (the least risky) to Grade Group 5 (the most risky):

  • Grade Group 1 – This group consists of Gleason scores of 6 and under, and indicates a low risk.
  • Grade Group 2 – This refers to Gleason scores of 7 where the primary cell pattern was graded as a 3 and the secondary cell pattern was graded as a 4. Grade Group 2 indicates an intermediate risk.
  • Grade Group 3 – This group includes Gleason scores of 7 where the primary cell pattern was graded as a 4 and the secondary cell pattern was graded as a 3. Grade Group 3 indicates an intermediate risk.
  • Grade Group 4 – This refers to Gleason scores of 8 and indicates a high risk.
  • Grade Group 5 – This includes Gleason scores of 9 and 10, and indicates the highest risk.

Prostate cancer cases that fall into the lower grade groups are more likely to respond well to treatment.

The team to choose for prostate cancer diagnosis and treatment

If you’re experiencing the symptoms of prostate cancer and you’re concerned that you might have this condition, it’s important that you promptly consult with an experienced medical provider. Although prostate cancer tends to be a relatively slow-growing malignancy, certain cases can be significantly more aggressive. And even when prostate cancer is progressing slowly, speaking to an expert as early as possible can lead to better outcomes and quality of life.

Fortunately, you can turn to Moffitt Cancer Center for prostate cancer diagnosis and treatment. We’re proud to be a National Cancer Institute-designated Comprehensive Cancer Center—the only one based in Florida—and the specialists in our Urologic Oncology Program excel at developing highly individualized treatment plans for each and every patient. What’s more, our robust clinical trials program provides prostate cancer patients with access to promising new treatment options that are currently unavailable elsewhere.

To learn more about Moffitt Cancer Center’s approach to prostate cancer diagnosis and treatment, call us today at 1-888-663-3488 or fill out a new patient registration form online—a referral is not required. We know that waiting to get your questions answered can be extremely stressful, so we’ll make sure to connect you to a cancer expert within just one day.

References

Understanding Your Pathology Report: Prostate Cancer
Gleason grading system: MedlinePlus Medical Encyclopedia
Gleason Score and Grade Group 
How Prostate Cancer Grows