Colonoscopy recommendations remain: Get screened at age 45

October 13, 2022
3-D transparent rendering of internal organs with the colon in red
Colon cancer is being detected in people of younger ages, which is why doctors now recommend colonoscopies begin at age 45 rather than age 50. Adobe Stock

News of a European study calling into question the effectiveness of colonoscopy for colon cancer screening might have you thinking of canceling the procedure.

Not so fast, say doctors with MUSC Hollings Cancer Center. Despite the headlines, the study did show the effectiveness of colonoscopy – just not as much as previous studies have shown, said Hollings director Raymond N. DuBois, M.D., Ph.D., who studies colon cancer and wrote a guest blog for the American Association for Cancer Research

And the study’s design and implementation have specialists questioning the results.

“I’m actually surprised they put that in the New England Journal of Medicine, given the problems with the way it was done,” said gastroenterologist Brenda Hoffman, M.D., chief of the Digestive Disease, Endocrine, and Metabolism Integrated Center of Clinical Excellence (ICCE) for MUSC Health.

The study in question, the Nordic-European Initiative on Colorectal Cancer, sought to test the effectiveness of colonoscopy screening in countries where the procedure wasn’t commonly recommended when the study began – Poland, Norway and Sweden. Using national registries, people between the age of 55 and 64 were either invited to have a colonoscopy or were assigned to the control group not to have a colonoscopy.

Only 42% of the people who were invited to have a colonoscopy actually got one.

“You can’t prevent cancer in those you don’t examine,” DuBois pointed out.

The study reported that people in the “invited to screen” group had a reduced risk of colon cancer of only 18% and didn’t show any difference in risk of death by colon cancer from the control group – yet those numbers included all of the people who were invited to have a colonoscopy but didn’t get one.

“There has been a significant uptick in the diagnosis of colon cancer in younger patients over the past decade, so we want to start screening at 45 to pick those up as soon as we possibly can.”

Raymond N. DuBois, M.D., Ph.D.

When the study authors ran the numbers assuming that everyone who had been invited to get a colonoscopy would get one, they calculated that colonoscopy reduced the risk of colon cancer by 31% and reduced the risk of death by colon cancer by 50%.

“I think it does say to us that colonoscopy is effective,” Hoffman said.

Both Hoffman and DuBois noted that the procedure itself, which was relatively unusual in the studied countries, differed in important ways from the standard in the U.S. The adenoma detection rate of some of the people performing the exam was lower than expected, they said.

“We know from literature from the U.K. and the U.S. what the expected polyp detection rate, or adenoma detection rate, is. Nothing I’m aware of would make these countries have different risks that would account for a lower detection rate," Hoffman said.

The adenoma detection rate is related to the length of the exam. But, unlike patients in the U.S. who usually undergo general anesthesia for colonoscopy, patients in the trial were unsedated or under-sedated, Hoffman said. Therefore, patients’ discomfort during the exam could have led endoscopists to be less thorough and to find fewer adenomas.

Adenomas are growths on the lining of the colon. Most aren’t harmful, DuBois said, but they’re removed as a precautionary measure.

“A portion of benign polyps will develop into cancer over time. We don’t know precisely which ones will progress to cancer, so we remove all of them that are identified to lower the cancer risk as much as possible,” he explained.

Another issue with the recent study was the short length of time the patients were observed. This was a 10-year study and, in some patients, it takes 15 to 20 years for colon cancer to develop. Thus, a longer study might show different results. The investigators plan to analyze the data again in five years. 

The doctors noted that here in the U.S., it’s now recommended that people begin colon cancer screening at age 45. There’s been “a very scary increase” in colon cancer rates among younger people, Hoffman said, and the data here shows that people should not wait until 50 to begin screening.

DuBois agreed. “There has been a significant uptick in the diagnosis of colon cancer in younger patients over the past decade, so we want to start screening at 45 to pick those up as soon as we possibly can,” he said.

The Colon Cancer Coalition states that colon cancer could become the leading cause of cancer death for adults under the age of 50 by 2030. This is particularly true in the South: A 2020 study identified “hot spots” for early-onset colorectal cancer among women, including a number of counties in South Carolina, and found that more than half of the hot-spot counties were in the South.

Hollings researcher Kristin Wallace, Ph.D., has been looking for genetic markers that could explain differences in outcomes among White and Black patients. Wallace’s research has shown that survival rates have improved for nearly all groups with early-onset colorectal cancer, except for Black patients with proximal colon cancer.

As part of its mission to decrease the cancer burden across the state of South Carolina, Hollings is working with the regional hospitals of MUSC Health to increase screening rates for five cancers, including colorectal cancer. Gerard Silvestri, M.D., and Marvella Ford, Ph.D., are working together to develop the program that will guide more patients to screening and work toward identifying biomarkers of cancer.

Although colonoscopy is the standard screening test, there are other exams that can also pick up on colon cancer, and research is underway to develop blood tests to determine which individuals would most benefit from colonoscopies.

That said, Hoffman noted, “The best screening test is the one that gets done.”

Symptoms of colon cancer

Colon cancer if often symptomless, which is why doctors recommend screening for all people. However, these symptoms should prompt you to talk to your doctor.

  • Blood in your stool.
  • Change in bowel habits that lasts more than a couple of days.
  • Abdominal pain.
  • Unexplained weight loss.