Staging is used to describe how much cancer there is in the body, and where it is when first diagnosed. Information from diagnostic tests is used to find out the size of the tumour, which parts of the colon or rectum have cancer, whether the cancer has spread from where it first started, and where the cancer has spread. Staging information is also used by your healthcare team to plan treatment and estimate your prognosis.
For colorectal cancer there are 5 stages – stage 0 followed by stages 1 to 4. Generally, the higher the stage number, the more the cancer has spread. Talk to your doctor if you have questions about staging. The colon and rectum are made up of different layers of tissues, and the stage often depends on which layer the tumour has grown into.
When describing the stage, doctors may use the words local, regional or distant. Local means that the cancer is only in the colon or rectum and has not spread to other parts of the body. Regional means close to or around the colon or rectum. Distant means in a part of the body farther from the colon or rectum. These same terms are used to describe cancer recurrence, if the cancer comes back after treatment.
Stage 0 (carcinoma in situ)
The cancer cells are only in the inner lining of the colon or rectum (mucosa).
The tumour has grown into the layer of connective tissue that surrounds the mucosa (submucosa) or into the thick outer muscle layer of the colon or rectum.
Stage 2 can be divided into stages 2A, 2B, and 2C.
- 2A: The tumour has grown into tissues beyond the muscle layer of the colon or rectum.
- 2B: The tumour has grown through the membrane that covers and supports the colon and rectum.
- 2C: The tumour has grown through the wall of the colon or rectum and into other organs, such as the bladder, prostate, or uterus.
There are cancer cells in lymph nodes near the colon or rectum. Stage 3 can be divided into stages 3A, 3B, and 3C, depending on where the tumour has grown and how many lymph nodes have cancer.
The cancer has spread to other parts of the body (called distant metastasis), such as the liver or lungs. This is also called metastatic colorectal cancer.
- 4A: The cancer is in only 1 organ or distant lymph nodes.
- 4B: The cancer is in more than 1 organ.
- 4C: The cancer is in the peritoneum.
Information taken from Canadian Cancer Society.