March 16, 2009 -- Question: What is the Gleason Scale?
Answer: The Gleason Scale or the Gleason Score was developed by a physician at the Mayo Clinic about 50 years ago. It gives us a hint of the aggressiveness of a prostate cancer. When a man has a biopsy of the prostate or the prostate is surgically removed, the pathologist will look at the biopsy under the microscope or look at the prostate under the microscope.
What the pathologist will do is give a number to what is seen; it's a general pattern. A Gleason score of one means that the tissue looks like normal prostate tissue, but it fulfills some of the criteria for malignancy. A Gleason score of five means that the tissue is so disorganized, it doesn't even look like normal prostate tissue: it looks like very aggressive, very angry cancer and two, three and four are incrementally toward more aggressive cancer.
Now an individual who gets their biopsy report or their pathology report will see that their pathology is ranked as Gleason three plus four or four plus five.
What that means is under the microscope, the pathologist sees a pattern that is generally, say, pattern three but there are elements of pattern four. That's a Gleason three plus four.
If a person has a Gleason four plus three, the pattern is generally pattern four with some elements of pattern three.
Where this becomes very important is people who have a Gleason score that has any elements of four in it really has a more aggressive tumor than a Gleason three plus three for example. We actually have data to show that people who have Gleason three plus three localized tumors who don't get treatment have a much better prognosis than people who have Gleason four plus four or even three plus four tumors.