MONDAY, Aug. 16, 2004 (HealthDayNews) -- Many doctors are performing unnecessary colonoscopies, a new study says.

The findings suggest physicians are not following clinical guidelines and overusing the screening test for colon cancer. In turn, this strains an already limited resource and eats up manpower and money, according to the report in the Aug. 17 issue of the Annals of Internal Medicine.

"We surveyed gastroenterologists and general surgeons to determine how they would recommend performing post-polypectomy surveillance," said study author Dr. Pauline Mysliwiec, an assistant professor of gastroenterology from the University of California Davis School of Medicine.

When a patient has a colonoscopy to screen for colon cancer, often the doctor finds polyps, Mysliwiec explained. "On the basis of the type of polyp we find, we make determinations as to when they should come back for subsequent procedures, if any. That's based on what we believe their risk for the development of colon cancer would be," she said.

Mysliwiec's team found most doctors recommended additional colonoscopies for almost all types of polyps found during the initial screening colonoscopy. "This included the most benign polyps, such as hyperplastic polyps, as well as large polyps and multiple polyps," she said.

According to Mysliwiec, the most recent guidelines recommend a follow-up colonoscopy between three to five years for small polyps called adenomas and no follow-up for hyperplastic polyps.

"We don't recommend surveillance colonoscopies when we find hyperplastic polyps -- those are not deemed to be precancerous," she said.

Moreover, with adenomas, which are considered to be a low risk for colon cancer, most doctors recommend colonoscopy more often than what guidelines recommend, Mysliwiec noted.

In their study, the researchers surveyed 349 gastroenterologists and 316 general surgeons.

The researchers found 24 percent of the gastroenterologists and 54 percent of the general surgeons recommended follow-up colonoscopies after finding hyperplastic polyps, despite guidelines to the contrary. In addition, 50 percent recommended having follow-up colonoscopies every three years or more often for adenomas.

This overuse of colonoscopy may be tying up resources that could be used for the initial screening of patients and for treating patients with symptoms of colon cancer, Mysliwiec said.

"In addition, you could be subjecting a patient to a risk from a procedure that may not be necessary," she added. "There are potential risks with a colonoscopy, such as a tear in someone's colon or a reaction to the sedative we use."

Mysliwiec noted that guidelines for follow-up colonoscopies differ between different medical societies. "One of the areas that merits further study is to look at why we have guideline variability among societies and try to achieve better consensus for guidelines," she said.

Many doctors may not be aware of recent guidelines and may be treating patients based on older guidelines or on the recommendations of other doctors, she said.

Mysliwiec cautioned that these findings apply only to patients with an average risk for colon cancer, not to patients who have a family history of colon cancer that may put them at high risk. "Patients should be screened for colon cancer and discuss their risk with their doctor," she said.

"There are different and sometimes confusing recommendations by different organizations as to guidelines doctors follow," said Dr. Len Lichtenfeld, acting deputy chief medical officer at the American Cancer Society. "We really don't know the right thing to do."

Lichtenfeld pointed out that some guidelines recommend doing a follow-up colonoscopy within one year. "So who is right?" he said. For example, the American Cancer Society recommends a follow-up should be done within three years after an adenoma is found, Lichtenfeld said.

In addition, Lichtenfeld said that, in some cases, hyperplastic polyps can be precancerous and so need to be followed with another colonoscopy.

"What's really needed is to figure out what the right thing is to do. And then we need to stand behind it," he said. "The differences in guidelines that confuse physicians also confuse patients, and may result in people not getting tests they need," Lichtenfeld said.

Guidelines from different groups should be similar to one another, he said. "That will go a long way towards trying to clear up the confusion that physicians and patients face when they try to make the right decision," Lichtenfeld said.

Dr. Alfred O. Berg, professor and chairman of the department of family medicine at the University of Washington, commented, "I find that many consultants are more aggressive about surveillance than the guidelines recommend."

"It takes a very strong patient and referring physician to argue with a consultant who is recommending more aggressive surveillance 'just to be safe'," he said. "We have a fascination with cancer screening, detection and surveillance in this country that often over-reaches the available evidence, and the fascination is shared by both patients and physicians."

Berg recommends that if a doctor recommends more aggressive screening or surveillance than guidelines suggest, ask why, and ask to see the evidence that supports their plan. "Then go with the evidence."

More information

The American Cancer Society can tell you about colon cancer.

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