National Survey of Doctors' Beliefs about How Frequently Colonoscopy Should Be Done after Removal of a Colon Polyp

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The summary below is from the full report titled "Are Physicians Doing Too Much Colonoscopy? A National Survey of Colorectal Surveillance after Polypectomy." It is in the 17 August 2004 issue of Annals of Internal Medicine (volume 141, pages 264-271). The authors are P.A. Mysliwiec, M.L. Brown, C.N. Klabunde, and D.F. Ransohoff.

What is the problem and what is known about it so far?

Most cancers of the colon begin as noncancerous (benign) polyps, which are growths on the inner surface of the tubelike large intestine. There are several different kinds of polyps, some of which may become cancerous growths and some of which rarely do. Doctors use a procedure known as colonoscopy (examination of the inside of the colon with a lighted tube) to check for polyps because removing a benign polyp prevents it from ever changing into a cancerous growth. After removing a benign polyp, doctors often repeat the colonoscopy periodically (surveillance colonoscopy) to ensure that no additional polyps have appeared. Several professional societies have written guidelines that advise doctors how often to repeat colonoscopy, depending on the chances that a particular kind of polyp is likely to recur and become cancerous. Because colonoscopy is expensive and requires a lot of physician time, it is important to tailor the frequency of surveillance colonoscopy to the likelihood that colon polyps will recur.

Why did the researchers do this particular study?

To determine whether gastroenterologists and general surgeons were following professional society guidelines on the frequency of surveillance colonoscopy.

Who was studied?

349 gastroenterologists and 317 general surgeons from all parts of the United States.

How was the study done?

Each study participant received a questionnaire in the mail that consisted of 40 questions about the doctor's beliefs, opinions, and practices concerning colon cancer screening. The questionnaire also presented 4 hypothetical patients with different kinds of colon polyps and asked doctors how often surveillance colonoscopy should be performed.

What did the researchers find?

Even when the initial colon polyp was a type for which professional society guidelines did not recommend surveillance colonoscopy, 25% of gastroenterologists and 56% of general surgeons would have performed the procedure and most would have done so every 5 years or more often. When a single polyp with relatively small risk for recurrence had been removed (professional societies recommend surveillance colonoscopy every 3 to 5 years in this instance), more than half of gastroenterologists and general surgeons would have performed the procedure within 3 years or sooner; one third of the general surgeons would never discontinue surveillance. In the case of large or multiple initial polyps (most professional societies recommend surveillance colonoscopy every 3 to 5 years), almost one half of gastroenterologists and 80% of general surgeons recommended having the procedure more often than once every 3 years.

What were the limitations of the study?

The results of the survey were based on what the doctors said they would do rather than what they may actually have done in practice.

What are the implications of the study?

It seems that doctors are greatly overusing surveillance colonoscopy, a finding that, if true, has serious adverse financial and manpower implications for the health system of the United States.