Colon Cancer Stages

Colon cancer stages have been established to ascertain the extent to which colon cancer has spread in the body of an individual. Colorectal cancer staging is very important because it helps in devising an appropriate treatment plan and also provides a fair idea about the survival outlook. The different stages of this type of cancer, which doctors have described, are listed below:

  • Stage 0: Stage 0 is the first stage of colon cancer staging. At this stage, cancer is only limited to the inner lining (often known as the mucosa) of the colon. The stage 0 of colorectal cancer is also referred to as carcinoma in situ.
  • Stage I: This stage of bowel cancer is characterized by the spread of cancer to the second and third layers of the colon. By this stage, the cancerous cells spread to the submucosa and the muscle layers of the colon. It is important to note that at this stage, the cancerous cells do not spread beyond the outer wall of the colon. This implies that cancer is still limited to the colon/rectum area of the body.
  • Stage II: This stage is divided into three sub-stages namely, stage IIA, IIB, and IIC.
  1. In the stage IIA of the cancer, the cancerous cells spread from the muscle layer to the outermost layer (known as serosa) of the colon or the rectum wall.
  2. Stage IIB is characterized by the proliferation of the cancerous cells beyond the serosa but these cells have not impregnated the nearby organs of the individual.
  3. Stage IIC marks the proliferation of cancerous cells to the nearby organs of an individual as they move beyond the serosa.
  • Stage III: The stage III of colorectal cancer is further classified into stages IIIA, IIIB, and IIIC.
  1. Stage IIIA marks the spread of cancerous cells to at least one but less than four lymph nodes that are in the periphery of the colon or rectum serosa. This stage also marks the formation of cancer cells in the tissues surrounding the lymph nodes. The stage IIIA of colorectal cancer can also signify the proliferation of cancerous cells beyond the inner most layer (instead of the outermost layer) of the colon or the rectum. The cancerous cells can then spread to 4-6 lymph nodes in close vicinity of the colon.
  2. Stage IIIB is characterized by the proliferation of cancerous cells in 7 or more lymph nodes near the colon.
  3. Stage III C of bowel cancer represents the spread of cancerous cells to the nearby organs, or the formation of cancerous cells near the lymph nodes.
  • Stage IV: Stage IV of colorectal cancer signifies the spread of cancer cells to nearby lymph nodes or organs. With an advancement of this stage, cancerous cells might start forming in one or more organs that are not near the colon, for instance, the lungs, liver, or the ovary.

Determining colon cancer stages in an individual is critical for establishing the best treatment plan.

colorectal cancer stages

Image courtesy of Johns Hopkins Digestive Disorders Library

Identification of Colon Cancer Stages: Tests and Procedures

Colorectal cancer staging is primarily done to assess the extent of spread of cancerous cells. Colon cancer staging involves the use of specific tests and procedures. Some of these are listed below:

  • CT scan: Computed Tomography or the CAT scanning process involves injecting a dye in the body, taking pictures of various parts of the body through x-ray machines and then developing them through a computer linked to the x-ray machines.
  • MRI scan: MRI scan involves the use of magnetic and radio waves for taking pictures of the colon. At times, gadolinium is also injected in the veins so that cancerous cells can be observed clearly in the images.
  • PET scan: PET scans are also used for observing malignant tumor cells. This process involves injecting radioactive sugar in the body. Cancerous cells take up more sugar than the normal cells and appear brighter in the images.

Other procedures used for colon cancer stages include lymph node biopsy, chest x-ray, surgery, and carcinoembryonic antigen assay (CEA). Colon cancer stages, if identified correctly, can help the doctor in devising an appropriate action plan for targeting the cancerous cells.

Colon Cancer Stages: Image courtesy of Johns Hopkins