Once you have had tests that show you have bowel cancer and whether it has spread, your doctor will tell you the stage of the cancer. This staging helps the doctor decide on the best treatment for you. The expected outcome of your disease is called the prognosis, but it is only a prediction and some people do not find it helpful or even prefer not to know.
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Staging bowel cancer
There are different systems for staging bowel cancer. The Australian Clinico-Pathological Staging (ACPS) and Dukes staging system have been widely used in Australia, but TNM staging (see below) is becoming more common.
Clinical stage – This is when staging is done before surgery. Clinical stage represents your doctor’s estimate of the extent of the disease and is based on the tests used to diagnose the cancer.
Pathologic stage – This is when staging is done after treatment, such as surgery. Pathologic stage uses the findings of the early tests, as well as the tests on the cancer tissue and lymph nodes removed during surgery. These results are usually available about a week after the surgery.
The pathologic stage is more precise in determining the extent of the cancer.
Used for many forms of cancer, the TNM system gives information about the tumour, nodes and metastasis. Each letter is assigned a number that shows how advanced the cancer is. If the letter X is used instead of a number, it means that it can’t be determined.
- T (Tumour) 1 to 4 – Indicates how far the tumour has grown into the bowel wall and nearby areas. T1 is a smaller tumour; T4 is a larger tumour that has grown into another organ.
- N (Nodes) 0 to 2 – Shows if the cancer has spread to nearby lymph nodes. N0 means that the cancer has not spread to the lymph nodes; N1 means there is cancer in 1–3 lymph nodes; N2 means cancer is in 4 or more lymph nodes.
- M (Metastasis) 0 to 1 – Shows if the cancer has spread to other, distant parts of the body. M0 means the cancer has not spread; M1 means the cancer has spread.
Prognosis means the expected outcome of a disease. You may wish to discuss your prognosis with your doctor, but it is not possible for any doctor to predict the exact course of the disease. In most cases, the earlier bowel cancer is diagnosed and treated, the better the outcome.
To come up with a prognosis, your doctor will consider:
- test results
- the type of cancer you have
- the rate and depth of tumour growth
- other factors such as age, fitness and medical history.
If bowel cancer is diagnosed and treated when it is still confined to the colon and/or local lymph nodes, it is known as early bowel cancer and has a good prognosis. If the bowel cancer has spread beyond the colon and local lymph nodes, it is known as advanced bowel cancer. The cancer may respond well to treatment, but a cure is less likely.