More on the Gleason Index

The following article is excerpted from PSA Rising - Prostate Cancer Survivor (News, Info & Support) in the hope readers may become more informed. I would encourage all our readers to visit the author's website.

This is used to grade how far prostate tissue is from normal, healthy tissue. After the doctor has taken biopsy samples of your prostate tissue, he or she sends them to a pathology lab. The pathologist looks at the samples under a microscope and grades the tissue on a scale of 1 to 5. The low number, 1, is for cells that look almost normal (very slow growing cancer). The high number, 5, is for cells that are least like normal prostate cells. Grades 2 to 4 fall in between.

Prostate cancer tumors often have areas of various grades. The pathologist identifies the two most prevalent grades. These are then added together to make the Gleason score (also called Gleason sum).

A result may look like one of these (not all possible combinations are displayed here):

3 + 2 = 5 or
2 + 3 = 5

3 + 3 = 6

3 + 4 = 7 or
4 + 3 = 7

4 + 4 = 8 or
3 + 5 = 8

4 + 5 = 9 or
5 + 4 = 9


(The order of the numbers matters and can affect treatment outcomes)

The Gleason grading system is named after Dr Donald F Gleason, the doctor who formulated it along with members of the Veterans Administration Cooperative Urological Research Group.

Normal body tissue cells are well-formed and differentiated to fit the functions of the specific body part. As you see in this image above, cells at the far right end (5) are quite shapeless and random compared to the moderately differentiated cells in the middle and the quite regular-looking cells at the left (1).

A small tumor with nearly normal structure (well differentiated) will behave in a more normal biological way. It may grow very slowly, with a doubling time of many years, and might never become a serious threat to health. A tumor that is moderately differentiated or undifferentiated is faster growing and more likely to spread.

High-grade tumor cells, having lost the special structure, or "architecture," that made them work as part of the prostate gland, may not even put out much PSA. This is one reason the Gleason grade and score are such key pieces of information for making treatment decisions.