(Reuters Health) - At age 76 the risks of a repeat colonoscopy may exceed the benefits for seniors whose previous screenings have found no signs of cancer, but many older adults don’t like the logic behind this guideline based on life expectancy.

A new study surveyed U.S. military veterans and found many believe age is not a good reason to give up regular colonoscopies even though most thought it was reasonable to use age in deciding when to start screening.

Nearly 50 percent of vets said age should never be used to decide when to stop screening, the study team reports in JAMA Network Open. And nearly one third said they were opposed to doctors using life expectancy as a factor in deciding whether a patient should get colonoscopy.

What the survey is showing is that “efforts to individualize screening in older adults are going to be met with some resistance, especially if we’re being explicit with the patient about using risk calculators to make decisions,” said Dr. Sameer Saini, a research investigator at the Veterans Affairs Ann Arbor Center for Clinical Management Research and an associate professor in the division of gastroenterology at Michigan Medicine.

“For a long time, it’s been recommended that screening in adults age 76 to 85 be more individualized. Doctors usually do this calculation through a sort of gestalt, looking at patients and deciding who will benefit. That’s not very reliable. And so a patient may go to one doctor and get a recommendation to have a colonoscopy and then another doctor might not.”

The new study analyzes responses from 1,054 veterans over age 50 who answered surveys designed to explore attitudes toward individualizing colonoscopy recommendations. Nearly half the vets, 49 percent, thought age should never be used to decide when to stop screening for colon cancer while 29 percent said they were “not at all comfortable” with cessation of screening even if it was unlikely the colonoscopy would make a difference to their health.

Veterans were more likely to be comfortable with a cessation of screening if they had a higher level of trust in their doctors and if they rated their own health as good.

The results might have been different if the vets hadn’t already had a colonoscopy, Saini said. “We’ve surveyed people who previously had a colonoscopy and what we know is that they were pretty positive about it,” he explained. “The people who have had multiple procedures done with negative results are the people who have the least amount to gain from another one. But because they have already bought into the benefits of colonoscopy, putting the brakes on that is a little more challenging.”

Part of the problem may be that doctors often don’t emphasize, or even bring up, the fact that the procedure comes with risks, which tend to increase with age, Saini said. “In many instances there may not have been much discussion at all.”

The biggest risk is from complications associated with anesthesia. And then perforation of the bowel and a risk of bleeding, he added. “They’re about one in 3,000 or 5,000 overall, but they go up when you’re (removing large polyps) and as you get older.”

Saini recommends that people over 75 discuss the pros and cons of repeat colonoscopies with their doctors. “I think people should think carefully about the potential benefits and harms of any medical procedure they are getting,” he said. “Asking their doctor to pause a little and explain more is appropriate. Sometimes doctors do need to be invited to have that conversation.”

“We’re a little bit a victim of our own success,” said Dr. Albert Wu of the Johns Hopkins Bloomberg School of Public Health in Baltimore, Maryland, who wasn’t involved in the study. “I believe that if we are not careful, as we increase appropriate screening for some people we will also increase inappropriate screening for other people.”

With changing guidelines, “patients can get a bit of whiplash,” Wu said. “They can be reluctant to let go of something they’ve been convinced can be lifesaving.”

“I’m inclined to personalize things when I talk to patients,” Wu noted. “For example, I might say, I wouldn’t recommend for my mother, who is your age, to have these tests because I don’t believe she would benefit and I can certainly see there are potential harms.”

SOURCE: bit.ly/2E7z8K4 and bit.ly/2QDFJCM JAMA Network Open, online December 7, 2018.