What are CT Colonography, the Fecal Immunochemical Test, and the Stool DNA Test?
The CT colonography (virtual colonoscopy), fecal immunochemical test, and stool DNA tests are newer and may not be options for everyone. Many insurance plans don’t cover these tests yet, and not all health care facilities and offices offer them.
CT colonography uses an imaging method called computer tomography (CT) scan. This type of test may be referred to as a "cat scan". CT colonography is like an x-ray, except instead of one image, the test takes many images quickly and combines them together so your doctor can see a full, three-dimensional picture of your colon. This test can be completed quickly and is less invasive than a traditional colonoscopy. However, if this test turns up suspicious areas in your colon, you likely will need further testing, such as a colonoscopy, to get a definitive result on what these areas are and how best to treat them.
Fecal Immunochemical Test
The fecal immunochemical test is similar to the fecal occult blood test. You collect stool samples and send them into a lab for testing. The test looks for the presence of blood in your stools. The main difference is that the fecal immunochemical test uses a more high-tech laboratory method to detect the presence of blood. For this reason, it may be a more accurate way to screen for blood in your stools than the fecal occult blood test. The fecal immunochemical test is similar to the fecal occult blood test in another way: if blood is detected, you will need follow-up testing, such as a colonoscopy, to determine the reason for blood in your stools.
Stool DNA Test
Like the fecal occult blood test and the fecal immunochemical test, the stool DNA test screens a stool sample that you have collected and sent into a laboratory for analysis. But instead of looking for blood, the stool DNA test looks for abnormal genetic material, called DNA, that may signal the presence of cancer in your colon. This test is not invasive and doesn't require special preparation, but it can be more expensive than other testing methods. Also, if the test does detect abnormal DNA in your stool, you will need a more invasive test, such as a colonoscopy, to follow-up.
The American Cancer Society website has detailed information on these tests.
Are There Any New Tests on the Horizon?
If you’ve always dreaded a colonoscopy, you may soon be able to get a blood test as a way to decrease the need for this more invasive procedure. A researcher at Tel Aviv University has developed a simple blood test to detect a protein in the blood given off by 90% of colon tumors and 80% of adenomas, the growths that can lead to colon cancer if untreated.
This test should be available within the next one to two years, and will be a boon to the colonoscopy-phobics among us.
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