Linking the USPSTF mammogram guidelines to their virtual colonoscopy recommendations

by Mark E. Klein, MD

“I think anytime you use science to kind of fundamentally change what people are used to, I think it’s a difficult thing to grapple with.” So spoke Ned Calonge, chair of the United States Preventive Services Task Force (USPSTF) in explaining the reaction to that group’s recommendation to radically alter their previous guidelines for breast cancer screening. Regrettably the incorrect application of science, as in the current case, often leads to erroneous conclusions and profoundly bad decisions.

The USPSTF’s recent pronouncement utilizes the same warped reasoning we have already witnessed from this organization.

In November 2008 this same group recommended against the use of a terrific diagnostic procedure, Virtual Colonoscopy, also know as CT Colonography, as an alternative to traditional colonoscopy for the early detection of precancerous colon polyps. Their verdict served as the basis for Medicare’s May 2009 decision to deny payment for this procedure. The data on this technique is crystal clear. It is far safer than traditional colonoscopy, of greater or equal accuracy for the detection of significant polyps as traditional colonoscopy, and as a bonus is less expensive.

Why did the USPSTF refuse to endorse a procedure enthusiastically recommended by numerous professional physician organizations, the American Cancer Society and the national Blue Cross Blue Shield Technology Evaluation Center, a group not anxious to add to the cost of healthcare? Because although they accepted that Virtual Colonoscopy was accurate in diagnosing colon polyps, they feared that the CT-based technique could identify possible abnormalities outside of the colon that might lead to further unnecessary testing and drive up the cost of screening; a theoretical and unsubstantiated risk.

What this group chose instead to ignore was the very real risk, in fact the guarantee, that some Medicare recipients would die because they failed to get adequately screened for colon cancer because this excellent diagnostic tool was unavailable to them. The sixteen members of the USPSTF completely missed the forest for the trees.

One thousand women must undergo mammographic screening to find seven breast cancers; for 993 women the procedure is a waste of time and money. Of course we have no idea which seven of the thousand will benefit, so we screen them all. Seven out of a thousand is a pretty small number. It seems like a lot of effort for a little gain, yet women have collectively decided that they are willing to accept these numbers to achieve the 35% reduction in breast cancer deaths that mammography has delivered.

The USPSTF, having performed no new studies but merely re-analyzed existing data, is now stating that although we know that some women age 40-50 will die from breast cancer under these new guidelines, it’s a small number relative to all of the financial and other costs that would be incurred to screen all women of this age.

Let’s frame this concept a bit more simply. Just about everyone who boards an airplane is interested only in arriving at their destination safely. Unfortunately there is an infinitesimal number of individuals—we call them terrorists—who wish to blow that airliner into fragments somewhere over Ohio. It’s a very small number relative to the volume of the flying public. Is it really worth it to do any airport screening at all? While we’re at it, should we bother to inspect every food facility? Only a fraction of one percent harbors salmonella. And how about those railings on stairs, or elevator doors that only open when the elevator is really there? Are they worth all of the expense to save the few who aren’t paying attention?

All of these situations involve infinitesimal risk, but the possible outcome of ignoring that risk is monumental. Screening for any disease, unless it has an absurdly high prevalence, is all about doing a lot for a relatively small yield, but not screening results in what we have collectively decided is an unacceptable outcome.

So which is it? Do we wish to find as many early breast cancers as we can, knowing that the costs will be high and that some women will be unnecessarily frightened and even biopsied to save a small number of lives, or not? Because if we do wish to find those cancers that if caught early will save lives, then shoot for the highest possible sensitivity. Screen young women and screen annually, or don’t screen at all.

The USPSTF’s recommendations are, if not outright dangerous, at the minimum the foolish implementation of good science.

Mark E. Klein is a radiologist at Washington Radiology Associates, in Washington, DC.

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