Diagnosis

Screening for colon cancer

Doctors recommend certain screening tests for healthy people with no signs or symptoms in order to look for early signs of colon cancer. Finding colon cancer at its earliest stage provides the greatest chance for a cure. Screening has been shown to reduce your risk of dying of colon cancer.

People with an average risk of colon cancer can consider screening beginning at age 50. But people with an increased risk, such as those with a family history of colon cancer, should consider screening sooner. African-Americans and American Indians may consider beginning colon cancer screening at age 45.

Several screening options exist — each with its own benefits and drawbacks. Talk about your options with your doctor, and together you can decide which tests are appropriate for you.

Diagnosing colon cancer

If your signs and symptoms indicate that you could have colon cancer, your doctor may recommend one or more tests and procedures, including:

  • Using a scope to examine the inside of your colon. Colonoscopy uses a long, flexible and slender tube attached to a video camera and monitor to view your entire colon and rectum. If any suspicious areas are found, your doctor can pass surgical tools through the tube to take tissue samples (biopsies) for analysis.
  • Blood tests. No blood test can tell you if you have colon cancer. But your doctor may test your blood for clues about your overall health, such as kidney and liver function tests.

    Your doctor may also test your blood for a chemical sometimes produced by colon cancers (carcinoembryonic antigen or CEA). Tracked over time, the level of CEA in your blood may help your doctor understand your prognosis and whether your cancer is responding to treatment.

Staging colon cancer

Once you've been diagnosed with colon cancer, your doctor will order tests to determine the extent (stage) of your cancer. Staging helps determine what treatments are most appropriate for you.

Staging tests may include imaging procedures such as abdominal and chest CT scans. In many cases, the stage of your cancer may not be determined until after colon cancer surgery.

The stages of colon cancer are:

  • Stage I. Your cancer has grown through the superficial lining (mucosa) of the colon or rectum but hasn't spread beyond the colon wall or rectum.
  • Stage II. Your cancer has grown into or through the wall of the colon or rectum but hasn't spread to nearby lymph nodes.
  • Stage III. Your cancer has invaded nearby lymph nodes but isn't affecting other parts of your body yet.
  • Stage IV. Your cancer has spread to distant sites, such as other organs — for instance, to your liver or lung.