Key Points for This Section

After colon cancer has been diagnosed, tests are done to find out if cancer cells have spread within the colon or to other parts of the body. There are three ways that cancer spreads in the body. The following stages are used for colon cancer: Stage 0 (Carcinoma in Situ) Stage I Stage II Stage III Stage IV

After colon cancer has been diagnosed, tests are done to find out if cancer cells have spread within the colon or to other parts of the body.

The process used to find out if cancer has spread within the colon or to other parts of the body is called staging. The information gathered from the staging process determines the stage of the disease. It is important to know the stage in order to plan treatment. The following tests and procedures may be used in the staging process:

• CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography.
• Lymph node biopsy: The removal of all or part of a lymph node. A pathologist views the tissue under a microscope to look for cancer cells.
• Complete blood count (CBC): A procedure in which a sample of blood is drawn and checked for the following:
  • The number of red blood cells, white blood cells, and platelets.
  • The amount of hemoglobin (the protein that carries oxygen) in the red blood cells.
  • The portion of the blood sample made up of red blood cells.
• Carcinoembryonic antigen (CEA) assay: A test that measures the level of CEA in the blood. CEA is released into the bloodstream from both cancer cells and normal cells. When found in higher than normal amounts, it can be a sign of colon cancer or other conditions.
• MRI (magnetic resonance imaging): A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the colon. A substance called gadolinium is injected into the patient through a vein. The gadolinium collects around the cancer cells so they show up brighter in the picture. This procedure is also called nuclear magnetic resonance imaging (NMRI).
• Chest x-ray: An x-ray of the organs and bones inside the chest. An x-ray is a type of energy beam that can go through the body and onto film, making a picture of areas inside the body.
• Surgery: A procedure to remove the tumor and see how far it has spread through the colon.

There are three ways that cancer spreads in the body.

The three ways that cancer spreads in the body are:

• Through tissue. Cancer invades the surrounding normal tissue.
• Through the lymph system. Cancer invades the lymph system and travels through the lymph vessels to other places in the body.
• Through the blood. Cancer invades the veins and capillaries and travels through the blood to other places in the body.

When cancer cells break away from the primary (original) tumor and travel through the lymph or blood to other places in the body, another (secondary) tumor may form. This process is called metastasis. The secondary (metastatic) tumor is the same type of cancer as the primary tumor. For example, if breast cancer spreads to the bones, the cancer cells in the bones are actually breast cancer cells. The disease is metastatic breast cancer, not bone cancer.

The following stages are used for colon cancer:

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As colon cancer progresses from Stage 0 to Stage IV, the cancer cells grow through the layers of the colon wall and spread to lymph nodes and other organs.

Stage 0 (Carcinoma in Situ)

In stage 0, abnormal cells are found in the innermost lining of the colon. These abnormal cells may become cancer and spread into nearby normal tissue. Stage 0 is also called carcinoma in situ.

Stage I

In stage I, cancer has formed and spread beyond the innermost tissue layer of the colon wall to the middle layers. Stage I colon cancer is sometimes called Dukes A colon cancer.

Stage II

Stage II colon cancer is divided into stage IIA and stage IIB.

• Stage IIA: Cancer has spread beyond the middle tissue layers of the colon wall or has spread to nearby tissues around the colon or rectum.
• Stage IIB: Cancer has spread beyond the colon wall into nearby organs and/or through the peritoneum.

Stage II colon cancer is sometimes called Dukes B colon cancer.

Stage III

Stage III colon cancer is divided into stage IIIA, stage IIIB, and stage IIIC.

• Stage IIIA: Cancer has spread from the innermost tissue layer of the colon wall to the middle layers and has spread to as many as 3 lymph nodes.
• Stage IIIB: Cancer has spread to as many as 3 nearby lymph nodes and has spread:
  • beyond the middle tissue layers of the colon wall; or
  • to nearby tissues around the colon or rectum; or
  • beyond the colon wall into nearby organs and/or through the peritoneum.
• Stage IIIC: Cancer has spread to 4 or more nearby lymph nodes and has spread:
  • to or beyond the middle tissue layers of the colon wall; or
  • to nearby tissues around the colon or rectum; or
  • to nearby organs and/or through the peritoneum.

Stage III colon cancer is sometimes called Dukes C colon cancer.

Stage IV

In stage IV, cancer may have spread to nearby lymph nodes and has spread to other parts of the body, such as the liver or lungs. Stage IV colon cancer is sometimes called Dukes D colon cancer.

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