Understanding Your Gleason Score, With Michael Leapman, M.D., M.H.S.

If you’ve been diagnosed with prostate cancer, you’ve probably heard about the Gleason score — but what exactly is it, and why does it matter? Michael Leapman, M.D., M.H.S., a urologist and associate professor at Yale School of Medicine, explains that the Gleason score is one of the most important tools doctors use to understand how aggressive a prostate cancer is and decide how (or whether) it should be treated.

The Gleason score comes from looking at prostate tissue under a microscope — either from a biopsy or after surgery. A specialized doctor called a pathologist examines the pattern of cancer cells and assigns two numbers based on how abnormal the cells look. These numbers are added together, creating a score that ranges from 6 to 10 (e.g., 3+3=6 or 4+5=9). To make things simpler, doctors also use “grade groups,” which range from 1 to 5. A score of 3+3=6 is grade group 1, meaning it’s the least aggressive form of cancer, while a 5+5=10 is grade group 5, the most aggressive.

Why does this matter? Because not all prostate cancers need immediate treatment. Leapman says that low-grade cancers (like Gleason 6 or grade group 1) often grow slowly and may never cause harm. In many of these cases, men can safely choose “active surveillance,” where doctors closely monitor the cancer with regular tests and biopsies, only stepping in if it shows signs of getting worse.

For more aggressive cancers — Gleason scores of 7 or higher — treatment is often necessary. These treatments may include surgery, radiation or newer methods like ablation. The intensity of treatment can vary. For example, a man with an intermediate Gleason 7 (3+4) might get radiation alone, while someone with a higher score (like Gleason 9) may need radiation combined with hormone therapy.

Sometimes, a Gleason score can change over time. That’s why follow-up biopsies during active surveillance are important. If a higher-grade cancer is found later, it may be time to move from monitoring to active treatment.

In short, understanding your Gleason score can help you and your doctor make more informed decisions about the best path forward for your care.