Grading refers to the appearance of the cancer cells when the biopsy sample is looked at under the microscope. The grade gives an idea of how quickly the cancer may develop.

There are several grading systems, but the Gleason system is the most commonly used. This system looks at the pattern of cancer cells within the prostate. There are five patterns, graded one to five (one being the least aggressive and five being the most aggressive). The biopsy samples are each graded and then the two most commonly occurring patterns are added together to get a Gleason score of between two and ten.

The lower the Gleason score, the lower the grade of the cancer. With prostate biopsies, the samples are usually too small to show grades 1 and 2, so it is most common to get scores from 6 to 10.

Low-grade cancers (6 or less) 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.

The stage of a cancer is a term used to describe its size and whether it has spread beyond its original area of the body.

Knowing the stage of the cancer and the grade helps the doctors decide on the most appropriate treatment. There are a few different staging systems for prostate cancer, and one is described below:

• T1 – the tumour is within the prostate gland and is too small to be detected during a rectal examination, but may be detected through tests such as a PSA test, a biopsy or a transurethral resection of the prostate gland – an operation to make passing urine easier, by removing part of the prostate gland, often referred to as a TURP. There are generally no symptoms.

• T2 – the tumour is still within the prostate gland but is large enough to be felt during a digital rectal examination or show up on ultrasound. Often there are no symptoms.

• T3/T4 – the cancer has spread beyond the prostate gland into the surrounding tissues.

T1 and T2 tumours are known as localised prostate cancer (also called early prostate cancer).

T3 and T4 are known as locally-advanced prostate cancer.

If the cancer has spread to other parts of the body this is known as metastatic, secondary, or advanced prostate cancer.