Grading and staging of prostate cancer
The stage of a cancer is a term used to describe its size and whether it has spread. The grade gives doctors an idea of how quickly the cancer might grow.
Knowing the stage of your cancer helps doctors decide the best treatment for you.
There are a few different staging systems for prostate cancer. Two of the most commonly used systems are a number staging system and the TNM staging system.
The simplified number system is described below:
The cancer is very small and confined to the prostate. It can’t be felt during a rectal examination.
The cancer can be felt as a hard lump during a rectal examination, but it’s still within the prostate gland.
The cancer has started to break through the outer capsule of the prostate gland and may be in the nearby tubes that transport semen (seminal vesicles).
The cancer has spread beyond the prostate gland to nearby structures such as the bladder or back passage (rectum), or to more distant organs such as the bones or liver.
If the cancer has spread to other parts of the body this is known as metastatic, secondary, or advanced prostate cancer.
If your doctors did a biopsy of your prostate, they will look at a sample of the cancer cells under a microscope to find out the grade of your cancer. Prostate cancer is graded according to the appearance of the cancer cells.
There are several grading systems, but the Gleason system is the most commonly used. This system can help doctors decide which treatment might be best, as it gives them more information about the cancer.
The Gleason system looks at the pattern of cancer cells within the prostate. There are five patterns, which are graded from 1-5. 1 appears very similar to normal prostate tissue whereas 5 appears very different to normal tissue.
The biopsy samples are each graded and then the two most commonly occurring patterns are added together to get a Gleason score of between 2-10. The lower the Gleason score, the lower the grade of the cancer. Low-grade cancers (6 or under) are usually slow-growing and less likely to spread.
A score of 7 is a moderate grade. High-grade tumours (8-10) are likely to grow more quickly and are more likely to spread. High-grade tumours are sometimes called aggressive tumours.
Prostate biopsies with a Gleason score of 2 are rare. It’s more common to get scores from 6-10.