At-Home Stool Test for Colon Cancer
Review of 19 studies found the exam spotted the disease about 79 percent of the time
Colonoscopy is widely considered the "gold standard" for screening, because it allows the doctor to visually inspect the interior of the colon -- and, if necessary, remove precancerous growths called polyps.
Chan said it's not yet clear how FIT and colonoscopy compare when it comes to cutting people's risk of dying from colon cancer.
There are studies under way, though. A large U.S. government trial is randomly assigning people to have either a colonoscopy or an annual FIT screening, then following their rates of death from colon cancer over 10 years. (In the United States, colonoscopy is the most common screening method, followed by stool testing. Few doctors perform sigmoidoscopy.)
For the new review, Liles and her colleagues analyzed 19 studies done since 1996, looking at eight different brands of FIT tests. They found that the tests' sensitivity did vary from study to study, but the discrepancy narrowed when the researchers excluded tests that are no longer on the market.
On average, the review found that FITs catch about 79 percent of colon cancers, and their specificity consistently tops 90 percent. That means the tests accurately give a negative result to more than 90 percent of people who do not have colon cancer.
One surprise, Liles said, was that FITs that require two or three stool samples performed no better than single-sample tests. That matters, she said, because people might be more willing to do the test if it's simpler.
FIT screening is already fairly easy. Like older stool tests, they're done with a take-home kit: You use a brush to get a stool sample, and then mail it to a lab. But unlike older tests, FITs don't require any diet or medication restrictions in the days before the test.
The simplicity of the stool test is an obvious advantage over colonoscopy screening, Liles said. But she agreed that more research is needed to know which screening test is more effective at saving lives.
The U.S. National Institute of Diabetes and Digestive and Kidney Diseases and the National Cancer Institute provided much of the funding for the review.