Gleason grading
If cancer cells are found in the biopsy samples, the pathologist will ‘grade’ them. The most common way of grading prostate cancer cells is ‘Gleason grading’. This is named after the doctor who developed it, and describes how abnormal the cancer cells look under the microscope. The Gleason grade gives the doctor an idea about how aggressive the cancer is likely to be and how quickly it is likely to spread outside of the prostate.
The cancer cells within the prostate may be at different stages of development, with some behaving more aggressively than others. The doctor takes this into account by looking at the most common types of cancer cell patterns in the biopsy sample.
Each of these patterns is then given a Gleason grade between 1 to 5, with 1 being the least aggressive and 5 being the most aggressive. The grades for each of the two most common types of cell are then added together to give the Gleason score. For example, if most of the cancer cells in the sample are grade 3, and the second most common pattern is grade 4, the Gleason will be 3 + 4, and the Gleason will be 7.
A Gleason of 4 + 3 also gives a Gleason score of 7, but shows that the cancer is slightly more aggressive. This is because the most common pattern made by the cancer cells is graded first, so a Gleason of 3 + 4 has more cells that are graded as 3, whereas a Gleason of 4 + 3 has more cells that have the higher grade of 4.
The Gleason system uses a scale running from 2 to 10. However very few patients have Gleason scores of less than 6, because the lower scores are now thought not to be cancerous2. Because of this a Gleason score of 6 is the lowest that you will normally see on a biopsy.
- If your Gleason score is 6 (or less) any cancer cells are less likely to spread. The cells may be described as being ‘well differentiated’, which means they look similar to normal prostate cells.
- Cancer that has a Gleason score of 7 is ‘moderately differentiated’, which means the cells look less like normal prostate cells and are more likely to spread.
- Cancer that has a Gleason score of between 8 and 10 is the most aggressive and most likely to spread. The cells are ‘poorly differentiated’, which means they look abnormal under the microscope.
References used in the production of this page.
1 National Institute for Health and Clinical Excellence. Prostate Cancer: Diagnosis and Treatment; Full Guideline. 2008
2 Berney DM. The case for modifying the Gleason grading system. BJU Int. 2007; 100 (4):725-726