Prostate Cancer Grading and Scoring

If cancer is found in your biopsy sample, it is assigned a "grade" based on how abnormal the cancer cells appear compared with normal prostate cells when viewed under the microscope.

The system most widely used to "grade" prostate cancer cells is the Gleason system, devised by Dr. Donald F. Gleason.

The Gleason system is based exclusively on the architectural pattern of the glands of the prostate tumor. It evaluates how effectively the cells of a cancer are able to structure themselves into glands resembling those of the normal prostate.

Normal prostate cells are perfectly differentiated. Once they become malignant, however, prostate cells become less differentiated. Cancer cells that are very different in appearance and function than healthy cells are associated with more aggressive forms of cancer.

The Gleason system assigns cells a grade from 1 to 5. Lower Gleason scores describe a tumor whose structure is nearly normal (well differentiated) that will probably not be very aggressive. Higher scores describe poorly-differentiated, more aggressive tumors.

The 5 Gleason Grades

Gleason Grade 1 A compact mass of pale, well-formed cells, with evenly placed, uniform "glands"
Gleason Grade 2 Cells are similar to those in Grade 1 but they do not form a circumscribed mass. There may be slight variation in size, shape, and spacing of the glands.
Gleason Grade 3 Most common grade by far and also considered well differentiated. Malignant glands show slight variation in size and shape. Glandular contours are round and somewhat uniform.
Gleason Grade 4 A big jump in loss of architecture. Disruption and loss of the normal individual gland unit. Fusion of glands forming a network punctuated by glandular lumens.
Gleason Grade 5 Shows a variety of patterns, all of which demonstrate no evidence of any attempt to form gland units. The cancer cells form solid sheets and clusters or may infiltrate the prostate as individual cells.

A Gleason "grade" for cancer cells should not be confused with your "Gleason score," which can range from 2 to 10.

The Gleason score is written as the sum of the two Gleason "grades" given to the two most predominant or prevalent cell patterns found when your biopsy sample was examined under the microscope.

If your Gleason score is an even number, ie. 2, 4, 6, 8 or 10, that indicates that 95 percent or more of the tumor was composed of a single predominant cell pattern, so the dominant pattern was counted twice.

But if your Gleason score is an odd number, the component numbers are an important part of the score -- because not all scores of 5, or 7, are in fact equal.

A Gleason score of 3+4=7, for example, would mean that the most prevalent cell pattern was 3 (moderately differentiated) and the second most prevalent pattern was 4 (poorly-differentiated). This would be better than a Gleason score of 4+3=7, where the most prevalent cell pattern was 4 (poorly-differentiated) and the second-most prevalent pattern 3 (moderately differentiated).

Gleason Scores

1+1=2 Lowest possible Gleason score, where both the primary and secondary patterns have a Gleason grade of 1
1+2=3
2+1=3
2+2=4
2+3=5 Very typical Gleason score.
3+2=5
3+3=6 Most commonly observed Gleason score.
3+4=7
4+3=7 Very typical Gleason score.
4+4=8
4+5=9
5+4=9
5+5=10 Highest possible Gleason score, when the primary and secondary patterns both have the most disordered Gleason grades of 5.


In general, the survival time for a patient following a diagnosis of prostate cancer is related to the Gleason score. The lower the score, the better the patient is likely to do. In one study, a Gleason score of 2 to 4 indicated about a 95 percent chance of survival at 15 years without aggressive treatment.

However, general principles do not always apply to individual patients. Statistics tell us only what happens to men as a large group. Men with low Gleason scores have been known to do poorly, and men with high Gleason scores have been known to do well.

It also should be obvious that that assigning Gleason grades is not an exact science. Seeking a second opinion of the same biopsy samples from a different pathologist is highly recommended.
All information provided in this site is offered for educational purposes only, and it is not intended nor implied to be a substitute for professional medical advice. Always consult your own physician or healthcare provider with any questions you may have regarding a medical condition.