What Does the Gleason Score Mean?
The Gleason score provides insight into the aggressiveness of the prostate cancer, or how quickly it grows or spreads. Lower scores suggest less aggressive tumors, while higher scores indicate more aggressive tumors.
Specifically, the Gleason score divides prostate cancer into three groups:
- Gleason 6: The cancer is low-grade, sometimes called “well differentiated.”
- Gleason 7: The cancer is intermediate-grade or “moderately differentiated.”
- Gleason 8–10: The cancer is high-grade or “poorly differentiated.”
Gleason scores below 6 are rarely used and indicate very slow-growing cancers that are less likely to be considered significant.
Although this ultimate score, also known as the Gleason sum, is an important figure for understanding a prostate cancer prognosis, it doesn’t tell the whole story. Pathologists also consider the individual grades that make up the sum when determining the overall aggressiveness of the disease. For example, a Gleason score of 4+3=7 (where the primary pattern is grade 4) indicates a higher-risk cancer than 3+4=7 (where the primary pattern is grade 3) because more of the cancer cells are grade 4 than grade 3.
Though uncommon, it’s also possible that the biopsy missed a higher grade or more aggressive cancerous area somewhere else in the prostate.
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