It was not so long ago that colorectal cancer screening was a remote topic for most Americans. That tenor is changing rapidly. With high-profile celebrities endorsing screening, bills pending in Congress and several states, and a rash of studies out examining the accuracy and cost-effectiveness of screening, momentum for mounting effective colorectal cancer screening programs is high, and colonoscopy figures prominently in that discussion.
Two separate studies, published in the July 20 New England Journal of Medicine, showed that flexible sigmoidoscopy misses proximal lesions (lesions in the ascending and transverse colon close to the small intestine) that are seen with colonoscopy. This fueled the move by some to embrace colonoscopy as the screening test of choice. Some read those studies as compelling enough to sound the death knell for fecal occult blood testing (FOBT) and flexible sigmoidoscopy, although others note that it was known for some time that flexible sigmoidoscopy could not detect proximal lesions.
Almost overnight, these studies created a movement for a stronger role for colonoscopy in screening. Now, a new crop of cost-effectiveness studies offer more specifics on the cost-effectiveness of colonoscopy. No doubt, they will intensify the debate over colonoscopy.
Cost-Effectiveness Studies
In an Oct. 18 Journal of the American Medical Association report, A. Lindsay Frazier, M.D., pediatrician at Harvard Medical School, and colleagues compared the cost-effectiveness of 22 different screening protocols. They found that a combined approach (annual FOBT plus flexible sigmoidoscopy every 5 years) was the most effective strategy, assuming a 60% compliance rate. "A once-every-10-year colonoscopy prevented fewer colorectal cancer deaths than the every-5-year flexible sigmoidoscopy," said Frazier.
Even so, Frazier is quick to point out that colonoscopy is still "a very effective" screening test. She believes that insurers should cover the test, both from a public health and a patient preference perspective. "Colonoscopy every 10 years was actually cheaper than annual FOBT along with every-5-year sigmoidoscopy over time, assuming a person gets three to four colonoscopies over a lifetime versus yearly FOBTs and more frequent sigmoidoscopies at age 50."
A second cost-effectiveness study in the Oct. 17 Annals of Internal Medicine compared the three most widely used modalities (annual FOBT, flexible sigmoidoscopy every 5 years, and colonoscopy every 10 years) against each other and generally confirms the cost-effectiveness of colonoscopy. Amnon Sonnenberg, M.D., staff physician at the Albuquerque, N.M., VA Medical Center, and co-authors wrote: "Colonoscopy represents a cost-effective means of screening for colorectal cancer because it reduces mortality at relatively low incremental costs."
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A third cost-effectiveness study, led by Rezaul K. Khandker, M.D., now at SmithKline Beecham Pharmaceuticals, analyzed cost effectiveness using a third-party payer perspective. Reporting in the Summer 2000 International Journal of Technology Assessment in Health Care, the authors conclude that flexible sigmoidoscopy performed every 5 years and an annual FOBT were the two most cost-effective screening strategies. Even so, in their model, they also showed that if the cost of colonoscopy is cut in half, it moves to the second most cost-effective position.
Troubling Questions Remain
William Baines, M.D., senior medical adviser at the U.S. Agency for Healthcare Research and Quality and senior author on the paper, said that "the price cut is based on a pretty big if. . . . What is being modeled is that a health plan might bargain with a gastroenterologist for a reduced charge for colonoscopy," making the colonoscopy more attractive economically. However, Baines pointed out that "a cost-effectiveness analysis is not a complete policy analysis," warning that "you shouldnt let it make the decision for you."
Martin Brown, Ph.D., chief of Health Services and Economics Branch at the National Cancer Institute, added, "The models are all correct in suggesting that under favorable, but reasonable and plausible assumptions, colorectal cancer screening can be favorably cost effective. . . . These models are very informative. Just by adding a fuller spectrum of issues, they stand as useful frameworks."
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"There are some nagging issues that must be resolved before we forge ahead" with any broad-based screening strategy, Brown pointed out. And he is not the only one calling for caution.
To date, no studies have been reported that examine colonoscopy for colon cancer screening and have used mortality as an end point. Although Sonnenberg recognizes that randomized controlled trials have long been the gold standard for selecting the best screening techniques, "we have to treat patients right now based on the evidence we have." Armed with the accuracy studies and his cost-effectiveness model, he feels that "colonoscopy is the best way to go."
But Harold C. Sox Jr., M.D., of the Department of Medicine at Dartmouth-Hitchcock Medical Center and past-head of the U.S. Preventive Services Task Force, views the colorectal cancer screening situation today as "analogous to the breast cancer situation before the Health Insurance Plan of New York mammography study. We have learned a lot from randomized controlled trials in understanding precisely the impact of these tests on cancer mortality. If we abandon the standard of randomized controlled trials," he cautioned, "we do so at our own peril."
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Joseph Selby, M.D., director of the research division at Kaiser Permanente Health Plans, questioned the relative safety of colonoscopy if it is diffused into community practice. "You have to remember that in the [July 20 NEJM study led by David A. Lieberman, M.D.], colonoscopy was performed by very senior people, in a high-throughput screening mode," said Selby. "With newer, less-experienced examiners trying to work faster with the price cut in half, I doubt you will see the same results."
Steven H. Woolf, M.D., professor of family practice at Virginia Commonwealth University in Fairfax, Va., also worries about potential harms. "Neither the accuracy studies, nor the cost-effectiveness analyses address whether there is more benefit than harm," he said. After multiplying out the uncertain number of bleeds and perforations with the procedure, "you have to ask whether it is ethical to expose patients to those harms."
Safety worries dont stop there. Brown and others wonder whether silent myocardial infarctions following colonoscopy, a nonsignificant finding in Liebermans research, might prove significant with further study. It is a concern other investigators have discussed.
Questions of feasibility also concern many observers. "We cant really do it because we dont have the people to do it," Selby said. "There is a national shortage of gastroenterologists. If you wanted to do it, you would use up all your gastroenterologists, and there would be no time left to deal with bowel obstructions, upper endoscopies, and liver disease."
Compliance was factored into all the cost-effectiveness analyses, but some doctors suggest that it is misguided to assume that compliance is necessarily static. "Just because compliance is low now, it does not mean it always will be," said David F. Ransohoff, M.D., professor of medicine, University of North Carolina, Chapel Hill. He believes that the climate surrounding colorectal cancer screening is not unlike the early days of mammography screening, when women did not readily come in for screening.
Selby offers other evidence that compliance can improve, pointing out that Kaiser Permanente in Northern California has successfully ratcheted up compliance with flexible sigmoidoscopy every 5 years to 70%, compared with a national average of 30%, by working hard to educate primary care physicians about the importance of screening.
With all the hoopla surrounding colon cancer screening, few researchers believe these most recent studies will put an end to the story. Some researchers have tried to take a step back and look at this with a longer view.
Commenting on her study and the accumulating research in this area, Frazier added: "If these studies lead more people to get screened, all the better. My worry is that people not feel like they are getting a suboptimal test, that you are only doing a marginal job if you dont get a colonoscopy, because that is how the field is going right now."
Ransohoff agreed that compliance is a big issue. "While we quibble about the best test, we may lose the bigger picture, namely to get one of those tests," he said. "Getting anybody to get screened at all is still the biggest challenge."
He added: "Until one modality shows very clear dominancewhich is not the case in these studiesand until important issues like safety are better understood, it may be useful to consider this kind of decision to be a toss up, as was first conceptualized by Jerome Kassirer, M.D., and Steven Pauker, M.D., years ago.
"They suggested that the situation can be understood and defused simply by recognizing it to be a toss up, and by giving broad leeway to physicians and patients to make a choice, rather than to be dogmatic about one choice or another."
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