When it comes to screening, what's cost effective?
The good news about colorectal cancer screening is that all forms of screening can save lives, according to David A. Lieberman, MD, chief of gastroenterology at Portland's Oregon Health Sciences University.
Randomized control trials have found that yearly fecal occult blood tests (FOBTs) cut colorectal cancer mortality by 30%, while case control studies have suggested sigmoidoscopy's efficacy. Physicians have inferred from those studies that colonoscopy—which examines all, not part, of the colon—is even more effective. (Two randomized controlled trials on sigmoidoscopy are now taking place.)
Further, Dr. Lieberman claimed that colorectal cancer screening is just as cost-effective as many other medical procedures.
"Compared to mammography, it's less costly in terms of life years saved," Dr. Lieberman explained. "And it's quite a bit less than cholesterol management because cholesterol medications cost so much."
But among the different screening options, which one is the most cost effective? Dr. Lieberman said that with 77 million Americans potentially eligible for colorectal cancer screening, the answer to that question could have a big impact on the allocation of health care resources.
The only problem is that there is no clear answer. An article in the July 16, 2002, Annals of Internal Medicine that accompanies revised U.S. Preventive Services Task Force screening guidelines said that "the cost-effectiveness of different [screening] strategies is unclear" and "a single optimal strategy cannot be determined from the currently available data." (The article is online at Annals.org.)
That's because while colonoscopy may be the most sensitive one-time test, physicians admit they don't know enough about the biology of colorectal cancer to declare the procedure the clear cost-effectiveness winner.
"To recommend that someone get screened every 10 years, you have to assume that polyps develop over a long period of time, but we don't know that for sure," explained Michael P. Pignone, ACP-ASIM Member, professor of medicine at the University of North Carolina-Chapel Hill and lead author of the Annals cost-effectiveness article. Just as in breast cancer, Dr. Pignone continued, colorectal cancer probably includes a subset of tumors that "develop very quickly from nothing, and may not even pass through a polyp phase."
To detect those types of tumors, shorter screening intervals—with annual FOBTs, for instance—might be preferable. And ultimately, the most cost-effective screening method may turn out to be the one that's accepted by the most patients, not necessarily the one that's most sensitive.
"If FOBT decreases colon cancer mortality by 20% and almost everyone gets screened and colonoscopy decreases mortality by 70% but only 20% of people accept it, the actual effectiveness of FOBT would be greater," explained Barnett S. Kramer, FACP, associate director for disease prevention at the National Institutes of Health.
"There are tradeoffs" among the different screening modalities, Dr. Kramer continued. "The bottom line is that any screening is better than none, and there is no right or wrong."
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