What Is a Gleason Score? A Surgeon Explains the Numbers

When my own biopsy came back, the first thing I looked for was the Gleason score. I had spent more than 40 years as a general and trauma surgeon reading pathology reports for other people. Reading my own was different. That number felt like a verdict. It is not a verdict, but it is one of the most important pieces of information you will get, so let me explain it in plain language.

This is education, not medical advice. Review your own report with your urologist and oncology team.

Where the Score Comes From

After a prostate biopsy, a pathologist looks at the tissue under a microscope. Normal prostate tissue has neat, orderly glands. Cancer cells lose that order. The more disorganized they look, the more aggressive the cancer tends to be. Dr. Donald Gleason created a grading system for this in the 1960s, and it is still the foundation of how prostate cancer is graded today.

Two Numbers Added Together

The pathologist identifies the most common pattern in your tissue and the second most common, and grades each on a scale. In practice, only patterns 3, 4, and 5 are used for cancer. The two numbers are added together. That is why you see scores written as 3+4=7 or 4+4=8. The lowest score used for cancer today is 6, and the highest is 10.

Why 3+4 Is Not the Same as 4+3

Both add up to 7, but they are not equal. In 3+4, most of the cancer is the less aggressive pattern 3. In 4+3, most of it is the more aggressive pattern 4. That difference matters for treatment decisions, so always look at the two numbers, not just the total.

The Grade Group System

Because the old scale confused people, doctors now also use Grade Groups:

• Grade Group 1: Gleason 6 (3+3). Low grade, slow growing.
• Grade Group 2: Gleason 3+4=7. Favorable intermediate.
• Grade Group 3: Gleason 4+3=7. Unfavorable intermediate.
• Grade Group 4: Gleason 8. High grade.
• Grade Group 5: Gleason 9 or 10. Highest grade.

What Your Score Means for Decisions

Many men with Grade Group 1 can safely choose active surveillance, which means careful monitoring instead of immediate surgery or radiation. Higher groups usually call for treatment. But the Gleason score is never the whole picture. Your PSA, the number of biopsy cores involved, imaging, and your overall health all count. I walk through PSA in understanding your Gleason score and PSA.

My Advice

Ask for a copy of your pathology report. Ask what your Grade Group is. And if your treatment decision depends on the score, it is reasonable to request a second pathology review, which I discuss in should you get a second opinion. Knowledge turns a frightening number into a useful one.

References

• Epstein JI, et al. The 2014 ISUP consensus conference on Gleason grading of prostatic carcinoma. Am J Surg Pathol. 2016;40(2):244-252.
• American Cancer Society. Understanding your pathology report: prostate cancer. cancer.org.
• National Comprehensive Cancer Network. NCCN Guidelines for Patients: Prostate Cancer.

Sunrise Institute is based in Florida and serves clients nationally through physician-led education sessions.