Many patients are getting screened for colorectal cancer more often than guidelines recommend, hints a new study.
That finding, along with other research published today in Archives of Internal Medicine, suggest that doctors need to better target the tests to patients who are most likely to benefit, and conserve limited screening resources and prevent complications by sticking to recommendations more closely, researchers said.
When colonoscopies are done according to guidelines, they "should lead to a dramatic reduction in colon cancer," Dr. James Goodwin, one of the researchers from the University of Texas Medical Branch in Galveston, told Reuters Health.
However, he said, "You cause more harm than good when you're screening too frequently. It's a bad thing to do for the patient."
U.S. cancer guidelines recommend testing middle-aged and older adults with a normal cancer risk every 10 years for colorectal cancer using colonoscopy. More frequent screening doesn't pay off because the procedure is uncomfortable and invasive with a risk of complications and costs a few thousand dollars -- and because this type of cancer typically grows very slowly, experts have determined.
Another kind of test for colorectal cancer, which looks for blood in the stool, is less invasive but must be done every year, according to guidelines. It also catches early cases of cancer, as opposed to colonoscopies, which are capable of finding the warning signs of cancer before it has actually developed, Goodwin explained.
The American Cancer Society expects about 100,000 people in the U.S. to be diagnosed with colon cancer this year, and another 40,000 with rectal cancer.
In one of the two new studies, Goodwin and his colleagues followed a group of 24,000 Medicare recipients, age 66 and older, who had normal results on their first colonoscopy. Unless they developed symptoms that hinted at colorectal cancer, those patients shouldn't get screened again for another decade, according to guidelines.
But over the next 7 years, about 1 in 4 of them had another colonoscopy with no clear medical reason listed in their records.
It's particularly important to limit the number of unnecessary colonoscopies because about 1 in 1,000 people who get the test will end up in the hospital from a complication, Goodwin said. Those potential complications include major bleeding or a tear in the colon.
The second study looked at about 200 military veterans age 70 and older who tested positive for blood in their stool. In the next 7 years, about half of them went on to have a colonoscopy - which can more definitively diagnose colorectal cancer and pinpoint its location - and half of them did not.
Dr. Christine Kistler of the University of North Carolina at Chapel Hill, who led the study, and her colleagues found that while a few of the patients who didn't have a follow-up colonoscopy were diagnosed with colorectal cancer later, about half of them died within 5 years from a different cause - suggesting the first test may not really have been necessary for many of them in the first place.
The finding "argues against this one-size-fits-all, screen everybody" mentality, Kistler told Reuters Health. "We really need to target screening to those patients that are going to benefit from it," including younger and healthier people.
"If you're going to die in 5 years, why would we subject you to colonoscopies and biopsies?" said Kistler.
Patients with a longer life expectancy had a better chance of benefiting from screening, while older and sicker patients were more likely to experience the burdens of screening - hassle, discomfort, and a risk of complications and further procedures - without any benefit.
Even before doing a non-invasive fecal blood test, Kistler said, "we need to do a better job of starting to think about, what's the right test for the right patient?"
Sometimes, if a patient has already had a colonoscopy recently and has no cancer symptoms, or is old and sick enough so that having early stage colorectal cancer might not matter so much, that answer might be no test, at least for the time being, the researchers reported.
The findings should not dissuade most people from getting routine colonoscopies or other tests for colorectal cancer, said
Dr. Michael LeFevre, a family doctor and co-chair of the United States Preventive Services Task Force, a federally-supported expert panel that makes screening recommendations.
Colorectal cancer "is one of the conditions for which we have very good science that screening saves lives," LeFevre told Reuters Health. And, he said, "we believe that many people are under-screened."
But he agreed that evidence shows that screening too often - or in very elderly patients - will generally do more harm than good, and that many doctors haven't fully gotten on board with screening guidelines.