Colonoscopies might not be that effective, new study says

Colonoscopies might not be as effective as originally thought, according to a new study.

The report, published in the New England Journal of Medicine, found that a group of some 22,000 people invited to get the procedure had just an 18% lower chance of getting colorectal cancer — and no significant reduction in the risk of cancer death.

Dr. Michael Bretthauer, a gastroenterologist who worked on the study, was dismayed by the findings.

“We may have oversold the message for the last 10 years or so, and we have to wind it back a little,” he admitted.

However, other experts have noted a hole in the study: The 18% figure included people who were invited to have colonoscopies but declined to have them.


colonoscope in the colon.
A colonoscopy is a procedure during which a camera is inserted through the large intestine in order to examine the colon and screen for cancerous polyps.
Getty Images/iStockphoto

When the results are re-examined only by looking at those who did receive the procedure, about 12,000 of the more than 28,000 who were invited, it was found to be much more effective.

Looking at just the population of people who did schedule the procedure, the risk of colorectal cancer was reduced by 31% and the risk of dying from colorectal cancer was cut by 50%.


Selective focus of an endoscope in hand of a doctor stock photo
Doctors still suggest that adults age 45 and up schedule the preemptive procedure.
Getty Images/iStockphoto

Bretthauer believes the benefits of a colonoscopy are somewhere in between, with the procedure probably reducing a person’s chances of colorectal cancer by 18% to 31%, and their risk of death by from 0% to 50%.

He notes that even his optimistic expectations are “on the low end [of] what I think everybody thought it would be.”

Most doctors still suggest that adults schedule the procedure by the time they reach their 45th birthday, if not sooner. or whenever advised by a medical professional.

“I don’t think anyone should be canceling their colonoscopy,” Dr. Jason Dominitz, the national director of gastroenterology for the Veterans Health Administration, told CNN.

“We know that colon cancer screening works.”

Colorectal cancer can also be screened with a stool test, flexible sigmoidoscopy or a virtual colonoscopy.

Actor Ryan Reynolds, 45, just recently publicized his life-saving colonoscopy to destigmatize the procedure and encourage others to schedule their own.