Calling Dr. Feynman

To quote Nobel prize winning physicist Richard Feynmen, "For a successful technology, reality must take precedence over public relations, for nature cannot be fooled," so we have some serious thinking about the use of random colonoscopies to prevent deaths from colorectal cancer, because a large study has shone that there is no impact for the procedure:

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.

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He stressed that the study does not invalidate colonoscopies as a useful screening tool. Colonoscopies are still a good test, Gupta said, but it may be time to reevaluate their standing as the gold standard of colon cancer screens. “This study provides clear data,” he said, “that it’s not as simple as saying, ‘Colonoscopy is the most sensitive test, and therefore it is the best.’ It still prevented cancers.”

Colonoscopies search for pre-cancerous polyps, known as adenomas, by inserting a camera up the rectum. If the endoscopist discovers a suspicious polyp, then it’s promptly removed, thus nipping the cancer before it spreads. Past research always showed that colonoscopy could put a huge dent, on the order of 70%, in the incidence and mortality from colon cancer.

But none of those studies were large randomized trials, the ultimate experiment in clinical research. So Bretthauer, of the University of Oslo and Oslo University Hospital, and several colleagues started one a decade ago, recruiting more than 80,000 people aged 55 to 64 in Poland, Norway, and Sweden to test if colonoscopy was truly as good as they all believed. Roughly 28,000 of the participants were randomly selected to receive an invitation to get a colonoscopy, and the rest went about their usual care, which did not include regular colonoscopy screening.

The researchers then kept track of colonoscopies, colon cancer diagnoses, colon cancer deaths, and deaths from any cause. After 10 years, the researchers found that the participants who were invited to colonoscopy had an 18% reduction in colon cancer risk but were no less likely to die from colon cancer than those who were never invited to 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 Sunday.

This study is not showing that colonoscopies miss cancers, it is showing that the outcomes do not change.

This is a lot like the PSA tests for prostate cancer, where the cancers were found and treated earlier, but there was no difference in outcomes.  If the cancer would have resulted in a death at age 60, there was no difference if it were identified at age 50, or at age 58.

Also, it should be noted that there is a lot more work to be done on the before we get a definitive word on this, so get your tests, if your insurance company pays for it, at least.

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Even if cancer therapy has progressed to the point where a 15-year follow-up fails to eke out a mortality reduction, UCSD’s Gupta pointed out that preventing cancer nonetheless can have a great benefit. The study still showed that colonoscopies reduced cancer incidence, which also means a reduction in surgeries, chemotherapies, immunotherapies, and other bad times. “The process of being treated is awful,” Gupta said. “If you ask patients if you’d rather be treated or prevented, a lot would say prevented.”

A secondary analysis also offers another silver lining, Gupta said. When the investigators compared just the 42% of participants in the invited group who actually showed up for a colonoscopy to the control group, they saw about a 30% reduction in colon cancer risk and a 50% reduction in colon cancer death. “That adds to a bunch of observational study data that suggests exposing people to colonoscopy can reduce risk of developing and dying of colon cancer,” Gupta said.