What is the Gleason score and what does it tell me?

A doctor, called a pathologist, will be sent the biopsy samples taken from your prostate. The samples are examined under a microscope to look at the cells. Normal healthy prostate cells are roughly the same size and shape. As cancer grows, the cells change and become unusual in shape and size. The more unusual or abnormal the cancer cells are, the more likely the cancer is to be aggressive or spread outside the prostate.

The doctor looking at the cells decides which type of cell is most common and which is second most common. Each of these two cell types is then given a grade from 1 to 5. A grade of 1 means these cells are the most normal looking or least aggressive, whilst cells given a grade of 5 are the most abnormal looking or most aggressive. These numbers are added together to give a final score out of 10. This is your Gleason score and it describes the grade of your cancer.

Because of modern biopsy techniques, grades of 1 and 2 are rarely used, so the lowest Gleason score likely to be reported is Gleason 6.

The Gleason Score reporting system will be phased out over the next few years as a newer prognostic grade group system is introduced.

What is the Prognostic Grade Group and what does it tell me?

The pathologist will still be sent the samples taken from your prostate and these will be examined under a microscope to look at the cell pattern.  Using the new grading system guidelines, the pathologist will grade the prostate cancer by simply numbering the prostate cancer from Grade 1 to Grade 5 with each of the grades having a likely outcome. Grade 1 will be the least aggressive and least likely to spread out-with the prostate while Grade 5 will be the most aggressive grade of prostate cancer. This system has been designed to be a simpler, more accurate and understandable way of reporting, making it easier for men and their families to understand the likely aggressiveness of their cancer.

However, until this becomes widely accepted it is likely that Gleason score and prognostic grade group will be reported together.

In practical terms this means:

Prognostic grade group Compares with a Gleason Score  of
Grade 1 Gleason score 6
Grade 2 Gleason score (3+4) =7
Grade 3 Gleason score (4+3) =7
Grade 4 Gleason score 4+4, 5+3 or 3+5 =8
Grade 5 Gleason score 9 and 10

What do these mean in terms of prostate cancer risk?

Result Low Risk Medium risk High Risk
Gleason score

 

Prognostic Grade Group

 

6

 

1

The cancer is likely to remain in the prostate and grow slowly (be less aggressive)

 

7

 

2-3

There is an increased chance of the cancer breaking out of the prostate

 

 

 

 

8-10

 

4-5

There is a greater risk that the cancer will grow quickly (more aggressive) and may possibly have already spread outside to prostate

 

PSA level ng/ml 10 or lower 10 – 20 More than 20