For decades, gastroenterologists put colonoscopies on a pedestal. If everyone would get the screening just once a decade, clinicians believed it could practically make colorectal cancer “extinct,” said Michael Bretthauer, a gastroenterologist and researcher in Norway. But new results from a clinical trial that he led throw confidence in colonoscopy’s dominance into doubt.
The trial’s primary analysis found that colonoscopy only cut colon cancer risk by roughly a fifth, far below past estimates of the test’s efficacy, and didn’t provide any significant reduction in colon cancer mortality. Gastroenterologists, including Bretthauer, reacted to the trial’s results with a mixture of shock, disappointment, and even some mild disbelief.