Screening for colorectal cancer is an important preventive health practice that saves lives. But is colonoscopy really the "gold standard" for colorectal cancer screening? In Episode 172 of the American Family Physician podcast, I provided my "hot take" on a recent randomized trial that was designed to inform the answer to this question. You can listen to it in the embedded player starting at 22:50 or read the transcript below. Health care professionals may also be interested in a more in-depth discussion that I participated in for Medscape.
Hi, I’m Kenny Lin, deputy editor of AFP and an expert in cancer screening guidelines.
In 2002, the US Preventive Services Task Force first recommended colonoscopy as a primary screening test for colorectal cancer (CRC) in adults. This was an uncharacteristic decision, since the first randomized trial of colonoscopy would not be published for another 20 years.
Since then, flexible sigmoidoscopy has virtually disappeared as a screening option, and colonoscopy has become the primary screening method in the U.S. Gastroenterologists call it the “gold standard” and portray stool-based tests as an inferior alternative to be offered only to patients who refuse.
Of course, colonoscopy is less convenient and has serious risks that stool tests don’t: perforations, bleeding, and infections. The Task Force and others have assumed that colonoscopy saves more lives than stool tests, which reduce CRC mortality by around 15%, or flex sig, which lowers it by 25 to 30%. So the first trial results were surprising, even shocking. After 10 years, the group invited to undergo screening colonoscopies developed fewer cancers, but there was no change in CRC mortality.
Some have argued that a longer follow-up period, higher adherence in the intervention group, and better trained endoscopists might have produced better results. But at a minimum, this landmark trial suggests that it is not accurate to inform patients that colonoscopy is the best test for CRC screening or ethical to recommend it preferentially.
Instead, we should explain that stool-based tests and colonoscopy have different benefits, harms, and screening intervals; that either test is better than none; and then let them decide. On a health system level, it may be worth taking another look at flex sig, an office procedure that older family physicians like me were trained to perform before the promotion of screening colonoscopy got out ahead of the evidence.