What tests are used to detect colorectal cancer?

We may detect colorectal cancer by one of the following tests, as recommended by the American Cancer Society, for men and women age 50 and over.

Tests that detect adenomatous polyps and cancer:

• Colonoscopy every 10 years (this is the preferred test, and it views the entire colon). This is the only test that examines the entire colon and allows removal of precancerous polyps. It is the screening method of choice and the gold standard of colorectal cancer screening.

• Flexible sigmoidoscopy every five years (this test views the lower one-third of the colon; if abnormal results are found a colonoscopy may be recommended)

• Double-contrast barium enema every five years (if one or more larger polyps are observed colonoscopy will be recommended)

• Virtual colonoscopy (CT colonography) every five years (if one or more larger polyps are observed colonoscopy will be recommended)

Tests that primarily detect cancer:

• Fecal occult blood test (FOBT) yearly

• Guaiac fecal occult blood test

• Fecal immunochemical test (FIT)

• Stool DNA test, frequency uncertain (this test detects abnormal DNA from cells passed in the stool)

If any of these tests are positive, a colonoscopy may be recommended.