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Colon Cancer Tests: The Best and the Rest

Tuesday, March 29, 2005; Page HE04

People should view colon-screening tests as they would any screening test, "just like women get Pap smears or mammograms," said Radhika Srinivasan, a University of Pennsylvania School of Medicine professor who helped develop new guidelines for colorectal screening. Her group's report suggests that African Americans start getting colonoscopies at age 45, five years earlier than other people.

Options for colon cancer screening include:

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Colonoscopy. Doctors examine the entire length of the colon using a camera-tipped instrument attached to a flexible tube. The test, during which patients are sedated, is widely recommended because it allows for the detection and removal of polyps, growths on the colon wall that can become cancerous. The test is generally recommended once every 10 years; more often for those with a family history of colorectal cancer or existing bowel disease.

Sigmoidoscopy. A physician uses a camera-tipped scope to examine the lower third of the colon. A less effective test than colonoscopy, this procedure does not require sedation, and doctors often recommend it in conjunction with a fecal occult blood test (see below) every five years.

Fecal occult blood testing. This noninvasive test is used to detect the presence of blood in the stool -- often the first warning sign of colorectal disease. A positive test is ordinarily followed by a colonoscopy. The blood test should be done once a year and can be combined with sigmoidoscopy.

Double contrast barium enema. An X-ray technician takes pictures of the large intestine before and after the patient is given a barium enema (a chemical that flows into the colon and shows up on the X-ray). The test, suggested every five years, is rarely recommended because it is "substantially less sensitive than colonoscopy [at detecting] large polyps and cancers" and does not allow doctors to remove polyps, says the report on the revised guidelines.

Virtual colonoscopy. This noninvasive screening test uses computers and X-rays to create images of the colon. Some physicians say it may become more widely used after it is studied more thoroughly.

Fecal DNA stool test. This noninvasive test detects genetic abnormalities in fecal samples. More research is needed before this test can be recommended for widespread use, according to the report.

-- January W. Payne


© 2005 The Washington Post Company


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