The Mammogram Mess

The last thing Democrats needed, with reform still not passed, was any kind of health-care controversy. Yet that's just what they got when the U.S. Preventive Services Task Force came out with a new set of guidelines on breast cancer screening, pushing back the suggested age for regular mammograms from 40 to 50. The uproar over the recommendation demonstrates a lot of the problems with how we deal with health care. It shows how opportunistic politicians can be -- the GOP, champions of women's health! -- and how as a country we have an inherent bias toward more health care, whether or not it's better health care. But the controversy also demonstrates how difficult it is to have a reasoned discussion and make good policy when scientific claims based on aggregates of cases are put up against vivid anecdotes from individual people.

Unsurprisingly, news reports about this issue have been filled with women testifying about the success of their own pre-50 mammograms. Since reporters always look for ordinary folks who can embody a controversy, they'll gravitate toward those who can say, "If I hadn't had a mammogram when I was 41, I'd be dead." The other side will be represented by a scientist wielding a stack of studies and figures.

Just to be clear, the task force – whose recommendations don't have the force of law over the choices the government makes, much less private insurers or doctors – didn't suggest a restriction on mammograms for woman until they hit 50. What they said was that regular mammograms before age 50, for women who have no risk factors like family history or a smoking habit, do more harm than good in the aggregate. They emphasized that they were making "a recommendation against routine screening of women aged 40 to 49 years. The Task Force encourages individualized, informed decision making about when to start mammography screening."

When someone says, "My sister got an early mammogram, and it found her cancer," they're talking about a person – not a hypothetical person or one statistic among many. Her experience could be typical or unusual. Whatever the case, we put much more weight on what we can see and what happens to the people we know than on abstract calculations of risk and reward.

So if you were the USPSTF and you wanted to persuade the public of the importance of your recommendations, you might write a vivid story with sympathetic characters to illustrate your argument. But scientists don't communicate in that language. And the reason they're recommending moving the age of universal regular mammograms back to 50 – that in total, the harms may outweigh the benefits – ends up seeming like little more than a footnote to this discussion.

The reason those harms are real is that as a diagnostic test, mammography isn't all that great. One 1998 study following a group of women over 10 years found that 23.1 percent had a false positive result on a mammogram. Since the median number of mammograms they had was only four, the researchers calculated that "the estimated cumulative risk of a false positive result was 49.1 percent ... after 10 mammograms." A false positive can mean more scans, radiation exposure, biopsies, and even surgery. This, on top of lots of anxiety. The researchers also found that these false positives resulted in $33 of additional spending for every $100 spent on screening.

Although people seem loath to talk about costs, there is a serious money consideration involved. By the USPSTF's estimates, it takes 1,904 women in their 40s being screened for a decade to save the life of one woman whose cancer would have gone undetected. As science journalist Merrill Goozner observes, that means that it costs as much as $20 million – not counting the interventions for false-positive results – for every life saved by regular mammograms for women in their 40s. You could ask whether one life is worth $20 million (maybe), but you could also ask whether we might find ways to spend $20 million that would save more than one life (almost certainly).

If we took those 1,904 women who have to get regular mammograms in their 40s, and multiplied it by the 49.1 percent who could expect a false positive, we would get 935 women who get false-positive results at some point in their 40s for every life saved. This is obviously a rough estimate, but it gives a sense of the magnitude of numbers we're dealing with.

Is this number too big? Acceptably small? There's no perfect answer. These decisions would be easier if there were some kind of universal utility scale on which we could place all harms and benefits and compare them with precision. But of course, there isn't. How many unnecessary surgeries is it worth to save one life? If it's your life, you'll have one answer. If you're the one undergoing the unnecessary surgery, you might have another. One survey found that 63 percent of women said they'd tolerate 500 false positives to save one life, and 37 percent said they'd tolerate as many as 10,000 false positives.

It seems awful to say to someone wielding their own story, "Yes, your cancer was detected. But you personally aren't really the point." Unfortunately, if you're trying to come up with judgments about an entire population to guide medical decision-making, any individual person really isn't. But that's why treatments are determined by human beings, not formulas. A formula can tell you whether a particular test is likely to be effective, but a patient and a doctor need to make the final decision on whether the test is worthwhile.

Plainly spooked by the controversy, given it occurred at such a critical moment, the administration's representatives tripped all over themselves to assure people that they don't care what the data said, and they are going to do everything they can to make sure anyone can get any test they want. The reaction wasn't too much of a surprise, given that public policy is so often made by ignoring critical facts to soothe people's emotions -- hence the general rule that if a law is named after a specific person, it's probably an absurd overreaction that does nothing to solve the problem it's meant to address.

This episode, in which a nonbinding recommendation by a panel of experts with no power to impose anything on anyone was whipped into a firestorm of fear-mongering, suggests we won't be having a reasoned discussion about the efficacy of mammograms anytime soon. And keep in mind that Republicans have made clear their opposition not just to allowing science to inform which kinds of treatments doctors recommend but to even performing the research that would tell us which treatments are most effective.

It has been estimated that as much as 30 percent of the money we spend on health care goes toward unnecessary tests and treatments. If the controversy over mammograms is any indication, our ability to bring that figure down is awfully small.

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