The Gleason Score is a measure of the aggression of prostate cancer, acquired by grading the two most common cancer cells in the prostate gland and adding them together. The higher the Gleason Score, the worse the prognosis. The scale is from 2 to 10, but most people fall into the 6 to 8 range.

The urologist takes a sample of the prostate gland through the rectum, and then grades the most common cancer cells found in the sample. Grades are from 1 to 5, ranging from cancer cells that are very similar to surrounding cells, to the entire gland being mostly cancer cells. After assigning a grade, he then looks for the second most common cancer cells found in the gland and grades it as well, also on a 1 to 5 scale.

This process is largely subjective, and so different urologists will come up with different Gleason grades and hence different Gleason scores; there is no way around this, but there are tests in the works that will provide a more objective assessment.

After grading the first and second most common types of cells seen, the urologist will add them together to get the Gleason score, from 2 to 10, with 10 being the poorest prognosis. However, there is more to the story than just this. The order that the grading is in can make a difference to prognosis. For example, a Gleason score of 7 could be consist of a grade of 4 for the first most common cell type, and a grade of 3 for the second most common cell type, or 4 + 3. Or, the 7 score could be because of 3 + 4. Obviously, a score of 7 consisting of 4 + 3 is worse than a 7 consisting of 3 + 4.

So each score will have it’s own fine-grained sub-scores, and some suggest that a third grade should be added for even more finely-tuned scoring, such as Gleason score 7 + Grade 3.

Once the Gleason score is known, then treatment options can be better evaluated, whether those be watchful waiting, radiation therapy, or radical prostatectomy.