Colonoscopy undercut by Gold-standard Study

Colonoscopy procedures have been promoted for decades by scores of doctors and hospital administrators. Adults have been urged to get a colonoscopy screening in the belief that it could make colorectal cancer nearly “extinct,” according to Norwegian gastroenterologist and researcher, Michael Bretthauer. Now, new findings from a clinical trial Dr. Bretthauer ran shows colonoscopy is rarely the life-saving procedure that has been promoted.

The trial’s primary analysis found colonoscopy cut colon cancer risk by perhaps a fifth, far below what past estimates had touted about the test. More importantly, colonoscopy didn’t provide any significant reduction in colon cancer mortality. Dr. Bretthauer and other gastroenterologists reacted to the colonoscopy trial’s results with both shock and disappointment.

Samir Gupta, a gastroenterologist at the University of California, San Diego and the VA, didn’t work on the trial, but he recognized its import:

“This is a landmark study,” said Dr. Gupta. “It’s the first randomized trial showing outcomes of exposing people to colonoscopy screening versus no colonoscopy. And I think we were all expecting colonoscopy to do better. Maybe colonoscopy isn’t as good as we always thought it is.”

Dr. Gupta nevertheless refused to reject colonoscopy as a diagnostic tool. He claimed, “Colonoscopies are still a good test,” though he admitted it may be time to reevaluate the procedures as the gold standard of colon cancer screens.

He said, the “[S]tudy provides clear data that it’s not as simple as saying, ‘Colonoscopy is the most sensitive test, and therefore it is the best.’ It still prevented cancers.”

What is a Colonoscopy?

Colonoscopy is a procedure that searches for pre-cancerous polyps called adenomas. The protocol involves a camera being sent up the rectum into the colon. The endoscopist who discovers a suspicious polyp can promptly remove it, hence, in theory at least, cutting a potential cancer before it can spread.

Past research, which now looks suspect, at best, typically showed colonoscopy could cut 70% out of incidence of, and mortality from, colon cancer. None of those studies were as extensive as this latest one that showed colonoscopy may not be worth the risk. No diagnostic tool is without risk, and that includes colonoscopy.

None of those studies included a large randomized trial, which is the gold standard in clinical research.

Gold Standard Study

By contrast, Dr. Bretthauer, of the University of Oslo and Oslo University Hospital, and several colleagues started this study a decade ago. They signed up more than 80,000 people aged 55 to 64 in Poland, Norway, and Sweden. The test was set to determine if colonoscopy was as effective as most doctors and patients believed (or had been taught) that it was. They randomly selected about 28,000 of the study participants to receive an invitation for a colonoscopy. The rest followed their usual care which did not include colonoscopy.

The researchers tracked the colonoscopies, colon cancer diagnoses, colon cancer deaths, and all-cause deaths. They found after 10 years that those who’d been invited for colonoscopy had an 18% reduction in colon cancer risk; however, they were no less likely to die from colon cancer than those who were never invited for screening. Of the participants who were invited to colonoscopy, only 42% actually did one. The team published their findings in the New England Journal of Medicine on Oct. 9, 2022.

Despite Study Results, Doctors defend Procedure 

The latest study results contradict findings from previous evaluations of colon cancer tests.

“We know from other screening tests that we can reduce cancer mortality by more than this,” said Jason Dominitz, the executive director of the national gastroenterology and hepatology program at the VA. He defended colonoscopies with an accompanying editorial in NEJM.

Dr. Bretthauer said, “(Colonoscopy) is not the magic bullet we thought it was. I think we may have oversold colonoscopy. If you look at what the gastroenterology societies say, and I’m one myself so these are my people, we talked about 70, 80, or even 90% reduction in colon cancer if everyone went for colonoscopy. That’s not what these data show.”

Other Testing makes more sense than Colonoscopy

He said the study results raise an important point for policymakers. Colonoscopy is more expensive, time-intensive, and more unpleasant than other options. He said many European countries balked at putting public health dollars towards a large, expensive program when fecal testing is cheaper, easier, and has greater uptake in certain studies.

“Now the European approach makes much more sense.” said Dr. Bretthauer. “It’s not only cheaper, but maybe equally effective.”



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