One of the most hotly debated topics in health care is how often to screen for different cancers. Current guidelines for colon cancer say it's okay to wait for ten years between the screenings, known in the medical world as colonoscopies. Some medical professionals and patients are calling for a change in that schedule, but, as Rose Hoban reports, a new study indicates that it is a reasonable guideline.
To do a colonoscopy, doctors insert a flexible probe with a very small camera into the patient's colon to examine the intestinal wall. An independent panel of experts in primary care and disease prevention has recommended that the procedure be done every ten years.
some doctors and patients have insisted on more frequent colonoscopies, arguing
that ten years is enough time for dangerous cancers to develop. These people
have been pushing for guidelines calling for people to be screened more
Part of the reason for this push is that the screening guidelines were based on evidence that isn't that strong, says Gastroenterologist David Ransohoff from the University of North Carolina. "There hasn't been direct evidence where people have been followed in large numbers, and followed intensely to learn, after a negative colonoscopy, what's the chance that you get cancer in some time afterwards?" he explains.
Ransohoff and his colleagues had an opportunity to answer that question. They accessed data from a company that paid for its employees to get colonoscopies every five years. Twelve-hundred people had the procedure.
In that time, Ransohoff reports, none of these employees got cancer, or had any evidence of cancer. He says these results strengthen the argument that a longer wait between colonoscopies is probably safe.
"The results of this study suggest that the screening guidelines and policies that we've got are now on stronger ground," Ransohoff says. He adds that it is an important study because even though the finding is what people have expected, this is the first time it has been documented by direct evidence in a study.
Ransohoff notes that in the United States, there's a tendency to want to use screening tests too aggressively, and he points to the debate over prostate cancer screening recommendations made recently by a government panel. He makes the point that many of these screening procedures involve some risk.
"Even though the complication rate of any one test is relatively small – one to two in a thousand have a serious complication, like bleeding that needs a transfusion, or perforation – if you do a large number of tests over 30 years – say six, or ten – that adds up to a not negligible rate of complications," he says.
Ransohoff says he'll continue working to determine the most appropriate interval for testing for this serious disease. His research is published in the New England Journal of Medicine.