Colonoscopy Benefits Lower Than Expected, Study Shows

Oct. 10, 2022 — Getting a colonoscopy might not offer as many benefits as we previously thought about what is considered a gold standard in cancer screening, according to a surprising new study out of northern Europe. 

After a 10-year follow-up study of people who were invited to receive a colonoscopy, researchers compared their results to a group of people who did not get the cancer screening. The former group had only an 18% lower risk of getting colon cancer, and the procedure didn’t make much difference in colon cancer deaths, according to results published in The New England Journal of Medicine.

Colon cancer — the second leading cause of cancer in the U.S. and the third in the world — is commonly found in adults over age 50.

During a colonoscopy, doctors insert a small camera through your anus to examine your large intestine and rectum (AKA your colon).

“The absolute risks of the risk of colorectal cancer and even more so of colorectal cancer–related death were lower than those in previous screening trials and lower than what we anticipated when the trial was planned,” says Michael Bretthauer, MD, a gastroenterologist from the University of Oslo Department of Medicine in Norway, and lead researcher of the study.

If you hate colonoscopies, don’t start jumping with glee just yet. The study also had its flaws. 

Researchers invited about 28,000 people enrolled in a long-term Northern European healthy study to get a colonoscopy. A little less than half — 42% — (actually received it. 

“It’s hard to know the value of a screening test when the majority of people in the study didn’t get it done,” says William Dahut, MD, chief scientific officer at the American Cancer Society.

However, study patients who did undergo a colonoscopy had a 31% decrease in the risk of colorectal cancer, and cancer-related deaths dropped in half as compared to those who were not screened. This result points to the value of continued screening.

Getting a colon cancer screening is still the best method of prevention, says Karen Knudsen, PhD, chief executive officer at the American Cancer Society.

“The American Cancer Society recommends colorectal cancer screening, including colonoscopy, for adults beginning at age 45,” Knudsen says. “There’s no reason to change that direction. Recommended cancer screenings should be a routine part of good health.”

Click here for more information on colon cancer screening.