Staging and prognosis for prostate cancer

Staging is the process of working out how large the cancer is and whether it has spread to other parts of the body. Prostate cancer is staged using the TNM system. The specialist assigns numbers for the size of the tumour (T), whether the cancer has spread to nearby lymph nodes (N), and whether the cancer has spread to the bones or other organs, i.e. whether it has metastasised (M). The lower the number, the less advanced the cancer.

The TNM scores are combined to work out the overall stage of the cancer, from stage 1 to stage 4 (see table below). Stages 3 and 4 are both considered advanced prostate cancer.

Stages 1–2

• The cancer is contained inside the prostate
• Localised/early

Stage 3

• The cancer is larger and has spread outside the prostate to nearby tissues or nearby organs such as the bladder, rectum or pelvic wall
• Locally advanced

Stage 4

• The cancer has spread to distant parts of the body such as the lymph glands or bone. This is called prostate cancer even if the tumour is in a different sort of tissue
• Metastatic

Grading describes how likely the cancer is to spread. A doctor called a pathologist works this out using a microscope to look at cells from a biopsy. Low-grade cancer cells tend to grow slowly, while high-grade cancer cells look abnormal and grow faster.

For many years, the Gleason scoring system has been used for grading the tissue taken during a biopsy. All men with prostate cancer will have a Gleason score between 6 and 10. A new system has been introduced to replace the Gleason system. Known as the Grade Group system, this grades prostate cancer from 1 (least aggressive) to 5 (most aggressive).

Grade group 1

• Gleason: 6 or less
• The cancer is slow-growing and less aggressive

Grade group 2-3

• Gleason: 7
• The cancer is faster-growing and moderately aggressive

Grade group 4-5

• Gleason: 8-10
• The cancer is fast-growing and aggressive

For men diagnosed with localised prostate cancer, the specialist will assign a level of low, intermediate or high risk to indicate how likely the cancer is to grow and spread. This is known as the risk of progression. Your doctor will work out this risk by considering the stage and grade, as well as your PSA level before the biopsy and your overall health, age and wishes. The risk category helps guide management and treatment.

Prognosis means the expected outcome of a disease. In general, the prognosis is better when prostate cancer is diagnosed while it is localised and at a lower grade.

You may wish to discuss your prognosis with your specialist. However, it is not possible for anyone to predict the exact course of the cancer. Test results, whether the cancer has spread (its stage), how quickly it might grow (its grade), and factors such as your age, level of fitness, and medical and family history are all important in assessing your prognosis.

Prostate cancer often grows slowly and even the more aggressive cases of prostate cancer tend to grow more slowly than other types of cancer. Compared with other cancers, prostate cancer has one of the highest five-year survival rates. For many men, prostate cancer grows so slowly that it never needs treatment. They live with prostate cancer for many years without any symptoms and without it spreading.