1. Other than stool tests, are there other ways of screening for colon cancer?
Yes. There are imaging tests that may be used to prevent and/or screen for colon cancer. One of these procedures may be chosen instead of screening annually with a fecal occult blood test:
Sigmoidoscopy is an examination of the rectum and lower colon with a lighted instrument. If polyps are found, they may be removed during the procedure and examined by a pathologist to see if cancer is present. If this is the chosen method of screening, once every 5 years is recommended.
Colonoscopy is a more thorough examination of the rectum and entire colon using a flexible tube. It also allows for the removal of any polyps. This procedure is recommended for screening every 10 years.
CT colonoscopy (virtual colonoscopy) is a less invasive procedure that uses computed tomography to visualize the entire colon. The recommended screening interval is 5 years.
2. Is the over-the-counter (OTC) at-home test just as good as other stool tests?
While the OTC tests that are dropped into the toilet are fairly sensitive, your health practitioner may prefer the gFOBT or FIT. The color change that is observed in OTC tests is subject to interpretation by the patient. Laboratory professionals are more experienced than most people in interpreting the sometimes subtle color change and are more familiar with sources of false-negative and false-positive results.
3. What kind of procedures might follow a positive FOBT or FIT?
An FOBT or FIT may be preceded or followed by a digital rectal exam to detect any growths that may be present in the rectum. A positive FOBT or FIT may be followed by sigmoidoscopy or colonoscopy, which enables the health practitioner to see inside the colon and identify polyps or other abnormalities (see Question 1).
4. Are there any other types of tests for colorectal cancer that are run on stool samples?
Yes. There is a stool DNA (sDNA) test available. The test can detect certain alterations to DNA (genetic material) in cancer cells that are shed into the stool. Studies have shown that the test has acceptable sensitivity, although it cannot identify all types of colorectal cancer. Guidelines released in March 2008 jointly by the American Cancer Society, the American College of Radiology, and the US Multi-Society Task Force on Colorectal Cancer added sDNA to their list of recommended testing options for colorectal cancer screening. The American Cancer Society recommends that if this test method is used, it should be repeated every 3 years.
This article was last reviewed on January 28, 2015. | This article was last modified on January 28, 2015.
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