A substantial number of physicians apparently aren't adhering to professional and medical society guidelines when it comes to follow-up colonoscopies for people who've already had a polyp removed. And that may mean that some people are getting procedures they don't really need, researchers report in the Annals of Internal Medicine (Vol. 141, No. 4: 264-271).

Researchers from the University of California, Davis, and the National Cancer Institute surveyed 349 gastroenterologists and 316 general surgeons about their practice of follow-up examinations. They compared the responses to guidelines issued by five groups: the Gastroenterology Consortium (1997), the American Society for Gastrointestinal Endoscopy (1997), the American Society for Colon and Rectal Surgeons (1999), the Society of American Gastrointestinal Endoscopic Surgeons (1997), and the American Cancer Society (1997).

Twenty-four percent of gastroenterologists and 54% of surgeons said they recommended follow-up colonoscopy after removal of a hyperplastic polyp, and most physicians in both groups said they would perform the procedure every 5 years or sooner. Yet the one medical guideline that discussed hyperplastic polyps did not recommend follow-up colonoscopy in this situation, since hyperplastic polyps are not considered precancerous.

More than half of the physicians said they would recommend follow-up colonoscopy within 3 years or sooner to patients who had had a small (less than 1 cm) adenoma polyp removed. Although these polyps do have the potential to turn into cancer, most of the guidelines recommend a follow-up examination no sooner than 3 years after removal of this type and size polyp.

This intensive surveillance is cause for concern, said lead author Pauline Mysliwiec, MD, MPH, an assistant professor of gastroenterology at UC Davis School of Medicine and Medical Center.

"We believe colonoscopy can be a life-saving procedure, but it shouldn't be done more often than necessary," she said. "When it's used inappropriately, it strains health care resources and puts patients at unnecessary risk."

Colonoscopy is expensive, typically costing between $1,500 and $1,700, and carries a slight risk of bleeding and colon perforation. And in some parts of the country, demand for the procedure has grown so high that patients must wait months to have it done. That could mean some people who truly need a colonoscopy -- to screen for colon cancer, for instance -- aren't able to get one in a timely fashion.

"Screening for colorectal cancer is vitally important," Mysliwiec said. "Since early detection makes a critical difference, it is even more important that we do what we can to promote the optimal use of colonoscopy resources."

Making the most of resources is likely to become even more important as the US population ages, said Robert Bresalier, MD, Professor and Chairman of the Department of Gastrointestinal Medicine and Nutrition at M.D. Anderson Cancer Center in Houston. He was not involved in the current research.

Colon cancer screening rates are still low in the US, he noted. But as more people reach screening age and efforts to increase attendance at screening increase, manpower to perform the examinations is likely to become a more widespread problem.

The study did not ask doctors about their recommendations for screening colonoscopy. The researchers also did not ask doctors why they were making particular recommendations for follow-up colonoscopies to patients who had certain types of polyps removed.

However, many doctors said research from medical literature had more of an influence on their decisions than professional guidelines. Just what that research might be was not clear; the researchers didn't get specific study citations.

But Mysliwiec said differences among the professional guidelines may be contributing to their lower rate of influence; doctors may be confused by the differences and as a result, err on the side of caution by making more aggressive follow-up recommendations.

Doctors may also be more cautious out of fear of lawsuits if they don't recommend follow-up exams and a patient goes on to develop cancer.

"I think that's a real concern," said Bresalier. "When we're doing screening and surveillance we're dealing with large groups of people, and there's always going to be an individual who's an exception to the general trend."

It's also possible that some doctors simply don't know what the guidelines are, or can't decide which guidelines to follow, Mysliwiec said. Among the five guidelines included in the study, those of the American Cancer Society seemed to carry the most weight; 53.6% of gastroenterologists and 49.4% of general surgeons rated them as very influential in their practice.

The study findings point to a need for greater consensus among professional organizations about practice guidelines, Mysliwiec said.

"Certainly reducing guideline variability would be helpful for both providers and patients," Mysliwiec said. "We have to home in on that issue of which guidelines to use."

Beyond that, physicians and public health experts need to find ways to make sure doctors know what the guidelines are, and ways to measure whether they’re being followed. It's a tall order, but one that ultimately could benefit patients.

"We have the opportunity to improve patient care and avoid over-burdening the health care system," Mysliwiec said. "We hope our findings will cause closer examination of current practices and promote more effective resource utilization."

Bresalier agreed that educating physicians is key to making sure they follow guidelines, which are designed to balance patient safety with cost effectiveness.

"While there's been a lot of attention placed on education in terms of having people screened and what tests are best for that, much less education has gone into follow-up," he said. "In the push for screening we've not spoken enough about what to with someone once they have a lesion. Not every polyp is the same."

Doctors must use their discretion for recommending follow-up procedures, he added, but "there has to be some thought going into what the evidence is and what we know in terms of evidence-based medicine."