Nearly one in three U.S. adults ages 50 to 75 hasn’t been screened for colorectal cancer, according to the Centers for Disease Control and Prevention. That might be because they fear getting a colonoscopy, which is the gold standard for detecting the disease. But there are good alternatives they should consider.
An annual take-home test that looks for blood in the stool, the fecal immunochemical test (FIT), is a highly accurate way to screen for colorectal cancer in people at average risk.
[FIT was recently endorsed in a consensus statement from the U.S. Multi-Society Task Force, which comprises major gastroenterological associations.
The test identifies antigens in the stool that indicate the presence of blood originating in the colon or rectum. Unlike older stool tests, such as the fecal occult blood test, FIT results can’t be thrown off by food or medication..
Some countries, such as Canada, have touted FIT as the screening of choice for colorectal cancer, thanks to the test’s low cost and noninvasive nature. The downside: If blood is detected in your stool, you’ll still need a follow-up colonoscopy.
“In a perfect world of screenings, we want to prevent cancer, not just detect it,” says David A. Johnson, M.D., professor of medicine and chief of gastroenterology at Eastern Virginia School of Medicine, past president of the American College of Gastroenterology, and co-author of the task force’s report.
A colonoscopy procedure can find cancer as well as potentially cancerous or precancerous growths (adenomas) so that the doctor can remove them on the spot. FIT and similar tests detect cancer after it is already present. It’s an important distinction and one that patients need to be aware of when deciding on a screening method.
Research published in 2014 points to a 3 percent decrease in the risk of cancer for every 1 percent increase in adenoma detection.
The U.S. Preventative Services Task Force doesn’t recommend one particular screening, instead leaving the decision to patients and doctors. It recommends fecal blood testing (annually), sigmoidoscopy (every five years), or colonoscopy (every 10 years), beginning at age 50 and continuing until 75.
In the United States, colonoscopies make up at least 60 percent of colorectal cancer screenings.
But they usually aren’t a patient favorite, thanks to an extensive laxative preparation that’s required to empty a patient’s bowels. There are also risks associated with colonoscopy, such as perforating a bowel. And colonoscopies are much costlier when compared with other screening methods, such as FIT.
Trials are currently underway to determine whether stool-based testing such as FIT is as effective or more effective at rooting out cancer than colonoscopy. But those results are not expected for several years. Research published in the Archives of Internal Medicine in 2012 pointed to patients being more than twice as likely to complete screening with FIT than if they had been offered only colonoscopy.
Implementing widespread FIT testing could be a problem, at least initially. No tracking system is currently in place to ensure the test is being offered, that the kits are being returned, that patients with positive results are following up with colonoscopy, and that patients with negative results will repeat the test in the recommended year.
So who stands to benefit the most from FIT? Johnson suggests candidates for FIT might include those who don’t have access to colonoscopy (geographically or financially), those who have a health-care provider who recommends yearly FIT testing first, and those who either refuse colonoscopy or cannot physically undergo it. In other words: FIT is also an important part of the screening arsenal, particularly in those cases where colonoscopy is not an option.
Which FIT test is best?
Our experts advise caution in using an over-the-counter FIT kit. Though they have been “FDA-cleared,” FIT tests sold directly to consumers in drugstores or online have not been adequately evaluated for quality and efficacy in large average-risk populations.
False-negative or false-positive results can have serious consequences for users. Rather, you should ask your doctor to provide you with a test kit.
According to the task force statement, “the OC FIT-CHEK family of FITs (Polymedco)—which include the OC-Light and the OC-Auto—have the best test performance characteristics.” They are used by many large medical groups such as Kaiser Permanente and the Veterans Health Administration. The stool samples are collected by patients and sent to a qualified lab for automated development and interpretation.
By the way, don’t believe claims in ads or on packages that FIT tests can diagnose diverticulitis, irritable bowel syndrome, or colitis.