The Task Force has found several kinds of screening tests effective, but the ones used most for people at average risk are colonoscopy, at a recommended 10-year interval, or FIT annually.
A newer entry, an at-home test sold under the brand name Cologuard that detects blood and cancer biomarkers in stool, may be used every three years, but a study found it to be less effective than most other methods and far more expensive than FIT.
When screening is recommended, how does FIT stack up against colonoscopy?
Higher-risk patients — including those who have had colon cancer or parents or siblings with colon cancer, those with inflammatory bowel disorders like Crohn’s disease, and those who have had abnormal previous tests, including multiple or large polyps — should seek out a colonoscopy, often on an accelerated schedule. The procedure involves inserting a viewing instrument through the anus to directly visualize an anesthetized patient’s colon.
A colonoscopy offers one distinct advantage: if the gastroenterologist spots polyps, growths that over time could become cancerous (although most don’t), these can be removed immediately. “You’re preventing cancer, snipping out the things that could lead to cancer,” Dr. Goodwin said. After a negative colonoscopy, patients don’t need another for a decade.
But the procedure’s complications increase with age, although they remain low; the most serious, a perforated colon, requires hospitalization. Cleaning out the bowel on the day before the procedure, in preparation, is disruptive and disagreeable, and Dr. Goodwin notes that older patients sometimes experience cycles of diarrhea and constipation for weeks afterward.
Rural residents may find traveling to a facility difficult. The use of anesthesia means that every patient needs someone to drive or escort them home afterward. The prospect of spending two to four hours in a facility, even one using rigorous safety measures, will cause some older adults to postpone testing because of Covid-19 fears.
The FIT, which is far more widely used in other countries, avoids many of those difficulties. A marked improvement over earlier at-home stool tests, it requires a sample from one day instead of samples from three, and imposes no food or drug restrictions. A positive result still calls for a colonoscopy, but the great majority of patients avoid that outcome.