How do you screen for colon cancer?

Answer:

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. Colon cancer screening is as effective as breast cancer screening when it comes to saving lives.

There are three ways to screen for colon cancer:

1. The first is a stool test that examines your bowel movements to check for blood.
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 large intestine, it may miss some cancers. Most health care providers recommend that the stool test and the 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.

The American Cancer Society makes the following recommendations:

Beginning at age 50, both men and women should have a screening test. Some recommend that African Americans begin screening at age 45. People with certain digestive diseases (such as ulcerative colitis) or a family history of colon cancer may need earlier and more frequent testing.

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 years
• Virtual colonoscopy every 5 years
• Yearly FOBT plus sigmoidoscopy every 5 years - this combination is preferred over the two tests alone

There is not enough evidence to determine which screening method is best. Colonoscopy is the most thorough method, but it takes longer, requires sedation, is slightly riskier (rarely, the bowel can be perforated), and is much more expensive than a sigmoidoscopy.

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). Capsule endoscopy is also being studied but it is not yet recommended by the American Cancer Society for standard screening at this time.

See also: Stool guaiac test

Smith RA, Cokkinides V, Eyre HJ. American Cancer Society guidelines for the early detection of cancer, 2006. CA Cancer J Clin. 2006;56:11-25.

Institute for Clinical Systems Improvement. Health Care Guideline: Preventive Services for Adults. 13th ed. October 2007.

Levin B, Lieberman DA, McFarland B, Smith RA, Brooks D, Andrews KS, et al. Screening and surveillance for the early detection of colorectal cancer and adenomatous polyps, 2008: a joint guideline from the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology. CA Cancer J Clin. 2008;58:130-160.

Mandel JS. Screening for colorectal cancer. Gastroenterol Clin North Am. 2008;37:97-115.