Screening for colon cancer; Colonoscopy - screening; Sigmoidoscopy - screening; Virtual colonoscopy - screening

Colon cancer screening can detect polyps and early cancers. Such screening can detect changes that can be treated before symptoms develop. Regular screenings may decrease deaths and prevent pain caused by colorectal cancer.

Several tools may be used, either alone or in combination, to screen for colon cancer:

1. The first method is stool tests that examine your bowel movements to check for blood. Polyps in the colon and smaller cancers often cause small amounts of bleeding that cannot be seen with the naked eye. The most common one used is the fecal occult blood test (FOBT). Newer stool tests are called the fecal immunochemical test (FIT) and stool DNA test (sDNA).
2. The second method is a sigmoidoscopy exam. This test uses a flexible small scope to look at the lower part of your colon. Because it only looks at the last one-third of the large intestine (colon), it may miss some cancers. Most health care providers recommend that the stool test and sigmoidoscopy be used together.
3. The third method is a colonoscopy exam. A colonoscopy is similar to a sigmoidoscopy, but it allows the entire colon to be viewed. You will usually be mildly sedated during a colonoscopy.

SCREENING RECOMMENDATIONS FOR AVERAGE-RISK PEOPLE

There is not enough evidence to determine which screening method is best. Discuss with your doctor which test is most appropriate for you.

Beginning at age 50, both men and women should have a screening test. Some health care providers recommend that African Americans begin screening at age 45.

Screening options for patients with an average risk for colon cancer:

• Colonoscopy every 10 years
• Double-contrast barium enema every 5 years
• Fecal occult blood test (FOBT) every year - if results are positive, a colonoscopy is needed
• Flexible sigmoidoscopy every 5 - 10 years, usually with stool testing FOBT done every 1 - 3 years
• Virtual colonoscopy every 5 years

A test called capsule endoscopy (swallowing a small, pill-sized camera) is also being studied, but it is not yet recommended for standard screening at this time.

SCREENING RECOMMENDATIONS FOR HIGHER-RISK PEOPLE

People with certain risk factors for colon cancer may need earlier (before age 50) or more frequent testing.

More common risk factors are:

• A family history of inherited colorectal cancer syndromes, such as familial adenomatous polyposis (FAP) or hereditary nonpolyposis colorectal cancer (HNPCC)
• A strong family history of colorectal cancer or polyps. This usually means first-degree relatives (parent, sibling, or child) who developed these conditions younger than age 60.
• A personal history of colorectal cancer or polyps
• A personal history of chronic inflammatory bowel disease (for example, ulcerative colitis or Crohn's disease)

Screening for these groups of people is more likely to be done using colonoscopy.

Recently there has been interest in several new screening tests for colon cancer, including checking DNA in stool samples and the fecal immunochemical test (FIT).

See also: Colon cancer

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