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What you need to know about stool based tests

You’ve likely heard of a colonoscopy. But do you know what a stool based test is?

The current guideline recommended stool based tests are the sensitive guaiac fecal occult blood test (gFOBT) and the fecal immunochemical test (FIT). FIT, in particular, is becoming a popular, low-maintenance colon cancer screening method. The FIT take-home test uses a collection tool to get a small sample of stool, which is sent to your doctor or lab by mail[J1].

We talked with Dr. James Allison, an expert in fecal blood tests for colon cancer, about this test and what it means for colon cancer screening. Allison is a clinical professor of medicine emeritus at the University of California - San Francisco and an adjunct investigator at the northern California Kaiser Division of Research.

Q: Colonoscopy has been considered the gold standard screening test for colon cancer. Now, we are hearing more and more about FIT tests. What is a FIT test, and why is it gaining popularity?

A: The term FIT means Fecal Immunochemical Test, and it is a test that is specific for human blood in the stool. It’s easily collectable, no diet is necessary, only one sample is necessary for most FIT, and it has a very good sensitivity for cancer. In addition to cancer this test when used in a program of repeated FIT testing can identify those few polyps most likely to become cancers before they ever become dangerous. If you have a positive FIT (human blood is detected in the sample), you will need further evaluation with colonoscopy.

Stool based tests should be done every year. It is for asymptomatic patients at average risk of colon cancer who are 50 and older. This means they have no past history of colon cancer, family history of colon cancer, or diseases such as inflammatory bowel disease that increase their risk of colon cancer.

Q: Who should get a FIT test?

A: This is for asymptomatic patients at average risk – meaning no past history of colon cancer, family history of colon cancer, or diseases such as inflammatory bowel disease that increase risk of colon cancer.

Q: What are the pros of FIT tests[J2]?

A: One of the most important things to know is they are noninvasive tests. There are no potential complications in having this test. Also, only one sample is required for most FIT tests, and there are no dietary requirements or medication restrictions. If you have a positive test, you’ve got to get a colonoscopy. Only 5 to 7 percent of patients who take the FIT test need to get a colonoscopy.

Q: What are the cons of a FIT tests?

A: A FIT test is a little more expensive than the standard FOBT guaiac test.

Q: Can FIT tests be done after a rectal exam by a physician during an office appointment?

A: No current guideline recommends digital rectal exam stool specimens be used to screen for colon cancer.

Q: How much do FIT tests cost?

A: They are typically covered by insurance. The Medicare reimbursement for FIT is $23. In California they are reimbursed at about $15 per test by Medical.

Q: How can someone get a FIT test?

A: The patient can ask their primary care physician. More importantly, the primary care physician should offer it as an option – and not as a second best option – for colon cancer screening.

Q: Is a FIT test really screening? Or is it just cancer detection?

A: We published an article in 2007 showing that fecal tests find polyps. Trials are being done now comparing FIT every year to colonoscopy every 10 years. We don’t have those results yet. When you do modeling, you see no difference in decreasing mortality or incidence.

Q: Many times, FIT tests are given out for free at health fairs. Do you support this?

A: The issues with it mostly are some of these tests have not withstood the test of time, and they are cheap knockoffs of the manufacturers who have spent the most money trying to standardize their tests and have real lab quality around them.

Q: How often do people stick to tacking an annual FIT test?

A: In the programs that are well organized, there is a very good comeback rate. It’s not perfect. That’s when you start employing other methods – an IT structure that identifies those people and sends reminders.

Kaiser does the FLU/FIT program. When they come for their FLU shot each year, they’re asked if they’ve been screened in last year. If the answer is no, they’re given a FIT test.

Want more info on stool based tests? Click here for our one-page handout.

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