Some People Might Only Need a Colonoscopy Every 15 Years, Study Suggests

Fact checked by Nick Blackmer

Key Takeaways

• A new study suggests that some people who had negative findings on their first colonoscopy can safely wait 15 years, rather than 10, for a follow-up colonoscopy.

• The findings come from a population study of people in Sweden. Experts say the results may not be generalizable to the U.S.

• Extending the interval between colonoscopies may reduce costs and the potential harm of unnecessary complications.

U.S. guidelines recommend getting a colonoscopy every 10 years starting at age 45. However, a new study suggests healthy people with no family history of colorectal cancer can wait 15 years between colonoscopies if results from the last one were normal.

The study included more than 110,000 people in Sweden with no family history of colorectal cancer and a negative finding from their last colonoscopy. Each member of that group was matched with up to 18 control individuals of the same age and sex. The control group either never had a colonoscopy or had a positive finding during their last screening.

The findings indicate that extending the interval from 10 years to 15 after a negative colonoscopy results in missing only one or two early colorectal cancer cases and one colorectal cancer-related death per 1,000 people. This change could avoid 1,000 unnecessary colonoscopies.

“We found that individuals with a first negative colonoscopy experienced a significantly lower risk of colorectal cancer and death from colorectal cancer for 15 years compared to unscreened controls,” said Mahdi Fallah, MD, PhD, senior author of the study and head of the Risk Adapted Cancer Prevention Group at the German Cancer Research Center. “We expected a longer interval might miss more cancers, but the findings suggest the risk is minimal.”

However, some experts said these findings shouldn’t change how people approach colorectal cancer screening.

“I don’t think that you can make this generalizable to the remainder of the world, and especially to the U.S. population. The Swedish population is probably very different than the U.S. population—we’re such a mixture of so many different cultures and backgrounds,” Reezwana Chowdhury, MD, a gastroenterologist at Johns Hopkins Medicine, told Verywell.

“In their population, they showed that they didn’t miss that many additional cancers or cancer-related deaths, but I don’t see that being the same here,” she added.

Related: How Often Should You Get a Colonoscopy?

Why Might Fewer Colonoscopies Benefit Patients?

Every time experts set or update a cancer screening guideline, they weigh the risks and benefits to individuals and the health system.

Colonoscopies can be a hassle to schedule, prepare, and pay for. And while colonoscopies are pretty safe procedures, they do carry some risks. The risk of perforation or bleeding during a colonoscopy is about four in 1,000.

Stretching the interval between colonoscopies could also save costs, which could be especially useful for certain underserved groups, said Robert Bresalier, MD, a professor of gastroenterology, hepatology, and nutrition at the University of Texas MD Anderson Cancer Center.

“[Colonoscopies] are associated with risk. If you could reduce the number over a lifetime, it would be more cost-effective and it would be safer,” Bresalier said.

In most parts of the world, people get a fecal occult blood test or other non-endoscopic test for colorectal cancer. If the test results are positive, they’re followed up with a colonoscopy. The U.S. is one of the few countries in which people typically get a colonoscopy first, largely because there are more gastroenterologists to perform the procedure here.

Related: Should Older Adults Be Concerned About Colonoscopy Complications?

Limitations of the Study

While the Sweden study factored in participants’ age and sex, it excluded lots of other important information about their health status, Chowdhury said.

For instance, the study didn’t provide information about people’s comorbidities or lifestyle factors, like obesity and smoking history. Those factors could contribute to a person’s risk for colorectal cancer.

In the U.S., there are increasingly more young adults diagnosed with colorectal cancer. Chowdhury said she’s worried that encouraging fewer colonoscopies could lead some of those cases to be missed.

“To not do anything for 15 years makes me uncomfortable, even for the average person,” Chowdhury said.

Bresalier said there is a limit to how much someone can conclude from this study because it’s not a controlled trial. To do that, researchers would have had to give one group a colonoscopy every 10 years and another group a colonoscopy every 15 years and compare their outcomes. Doing so would take a long time and could be unethical since it’s well-known that colonoscopies effectively detect and prevent cancer.

Related: U.S. Doctors Rebuke the New Study That Questions Colonoscopy's Effectiveness

Will U.S. Screening Guidelines Change?

Rather than indicate that the intervals between colonoscopies should be extended, Bresalier said the study strengthens the evidence that the 10-year interval is sufficient.

It usually takes 10 years for a polyp to develop from harmless to cancerous. A 2023 study showed that if someone has a normal colonoscopy, the likelihood of them developing colorectal cancer over 10 years is extremely small.

“I do think it’s reassuring and confirmatory of what we’ve found with studies and practice guidelines that a 10-year interval in a person with a normal index colonoscopy is okay,” Bresalier said. “People sometimes worry about the 10 years that it’s too long, and maybe we should do it sooner.”

Importantly, the researchers only tracked when study participants got colonoscopies, not when they took at-home stool tests, like Cologuard and FIT tests.

Stool tests can be useful for people who are at risk for anesthesia complications or those who don’t want an invasive procedure.

Related: This Low-cost Cologuard Alternative Is Just as Effective at Colorectal Cancer Screening

Fallah said that using cheaper, non-invasive stool-based tests could supplement a 15-year screening interval to help catch the one case per thousand that his team estimated an extended interval would miss.

However, it is only during a colonoscopy that a doctor can remove polyps to prevent colorectal cancer. While most of the current stool and blood tests are sensitive enough to pick up cancer, they aren’t very good at detecting pre-cancerous polyps.

Besides, Cologuard, a popular stool-based test in the U.S., has a false positive rate of up to 13%. A positive result from a fecal test may lead to CT scans and other expensive tests that could require more resources than an initial colonoscopy might have, Bresalier said.

“Doing anything is better than doing nothing,” Bresalier said. “The question is, how much tolerance do you have for a test that is not going to pick up every cancer and every polyp?”

It’s not out of the question that an extended interval is safe or that non-invasive tests could one day make for an adequate colonoscopy substitute, Bresalier said. For now, though, the research isn’t yet robust enough to change U.S. guidelines.

“A 15-year interval may, in the end, be a reasonable thing to do. But right now, we can feel comfortable with the 10-year interval and look to the future to see maybe a longer interval might be reasonable,” Bresalier said.

Read Next: A New Blood Test to Screen for Colorectal Cancer Shows Promise

What This Means For You

People at average risk for colorectal cancer should start getting screened at age 45. Younger people who have a family history or a history of inflammatory bowel disease may get screened younger.

Read the original article on Verywell Health.