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 moments 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. The patient usually is 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. There are five screening options:

• Fecal occult blood test (FOBT) every year - if results are positive, a colonoscopy is needed
• Flexible sigmoidoscopy every 5 years
• Yearly FOBT plus sigmoidoscopy every 5 years - this combination is preferred over the two tests alone
• Double-contrast barium enema every 5 years
• Colonoscopy every 10 years

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

Recently there has been interest in several new screening tests for colon cancer: Checking DNA in stool samples, virtual colonoscopy, and capsule endoscopy. However, the tests are not recommended 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.