Newsletter #70–Mar./Apr. 2002
From the Executive Director:
Facing Reality: The Latest Mammography Controversy
Every time a report is released that questions the benefits of mammography screening, the reaction from the American Cancer Society, the medical establishment, and the press is enough to make you think that the U.S. Supreme Court has just declared motherhood and apple pie to be unconstitutional. The most recent uproar on the subject began last year when the Lancet published a meta-analysis concluding that there is no reliable evidence that regular screening mammograms reduce the risk of dying of breast cancer for any age group.
In light of the commitment that BCA and many other breast cancer organizations share toward finding a better detection method, the recent flurry of mammography “news” seems like a good time to:
- Take a look at why reports about whether mammograms work are so hotly debated, and why those debates are unlikely to ever be resolved;
- Consider what it will take to move the breast cancer research agenda past mammography; and
- Address what women should do in the meantime.
First, a few words about the report in the Lancet: two Danish researchers looked at seven large studies of mammography screening conducted over more than 20 years. The study was done on behalf of a the Cochrane Collaborative, a well-respected international organization that assesses medical information in an effort to make sure that recommendations about medical procedures are based on sound evidence. The report concluded that none of the older trials that comprise the basis for mammography screening programs were well designed, and that the more recent trials showed no statistically significant reduction in breast cancer mortality rates as a result of mammography screening.
Keep in mind that the review in the Lancet was of screening mammography, or mammograms given to evidently healthy women who have no symptoms of breast cancer. It does not address the effectiveness of diagnostic mammograms, those given to women who have a breast lump or other symptom that requires investigation.
Also, the Lancet study does not say that mammography screening programs do not reduce the death rate from breast cancer; it says there is no evidence that they do so.
Why do reports that question the benefits of screening mammography create a furor? Ever since the first studies indicated that mammography screening might reduce deaths from breast cancer, a large industry has grown up around these exams. Government agencies, nonprofit organizations, and many corporations participate in major public education campaigns urging women to get annual mammograms. They also make the machines and film that are used in giving millions of mammograms each year.
To make this investment worthwhile, women have to have mammograms, so millions of dollars are spent every year touting the benefits of mammography. With so much invested in encouraging women to have mammograms, any report that suggests that the technology doesn’t work nearly as well as we’ve been led to believe raises the concern that women will stop having the procedure. And many doctors are swayed by the propaganda; they refuse to even look at the evidence that undermines such screening.
Many press reports of the Lancet study pointed to the need for more research to resolve the question of whether mammography screening saves lives. But the only kind of research that can truly resolve the question—randomized controlled trials where some women get mammograms and some do not—is not likely to happen in this country because of the heavy financial investment in mammography, and because the American medical establishment remains convinced, despite the lack of evidence, that mammograms save lives.
A Harvard instructor of “prevention” acknowledged as much when she told the Washington Post that such a study would mean “keep[ing] mammography away from the control group [and] no one here is going to sign up for that.” Or, as Barnett Kramer, associate director for disease “prevention” at the National Institutes of Health put it, once a program has been highly promoted and advanced as a way to save lives, it can be difficult to suggest that guidelines be revised.
How have mammograms been promoted as a way to save lives? The promise has always been phrased as this: for women over 501, annual mammograms reduce their chances of dying from breast cancer by 30 percent. But not even the studies on which such claims are based (the same ones criticized by the Lancet report) promise an individual woman anything. Instead, they point—accurately or not—to the reduction in overall mortality from breast cancer when large numbers of people are screened with mammograms.
These population-based results do not translate into an individual woman’s chances of dying from breast cancer found by a mammogram. An individual woman whose breast cancer is diagnosed based on a mammogram is not 30 percent less likely to die from the disease than she would be had her disease been found some other way. Her chances of dying from breast cancer are either 100 percent or 0 percent.
In other words, the question is not whether mammography works or doesn’t; it’s whether “early detection”—by mammogram, breast self exam, clinical exam, or happenstance—makes a difference in whether a woman lives out her normal life expectancy after a breast cancer diagnosis. And the answer is: it depends. It depends on what kind of breast cancer she has, how aggressive it is, and how her disease responds to treatment.
This distinction between population-based results and individual outcomes was highlighted by a prospective, randomized study in Canada that looked at the benefits of mammography as compared to other currently available detection strategies. The study of nearly 40,000 women after 13 years of follow-up showed that women who regularly received mammograms and clinical breast exams by doctors trained to do them are no less likely to die of breast cancer than women who receive the clinical exams alone. (BCA reported the results of the Canadian study more than a year ago in “Questioning Mammography,” BCA Newsletter #63, Jan/Feb 2001.)
But the U.S. medical establishment criticized the Canadian study before the ink had dried, in much the same way as the American Cancer Society (ACS) criticized the recent Lancet meta-analysis. The ACS spokesperson who commented on the Lancet report promised that the organization would review the study, but, despite the fact that that review had not yet occurred, saw nothing that would lead the ACS “to question the evidence and wisdom of screening mammography for women 40 and older.”2
So, when the San Francisco Chronicle publishes an editorial noting that the Lancet study has not prompted “experts at the American Cancer Society to change their recommendation for an annual mammogram,” it’s hardly news. Given the ACS’s investment in and ties to the mammography industry, we can expect the organization to change its recommendations on mammography around the same time that the moon turns to green cheese.
Clearly, organizations and government agencies have staked out their positions on mammography screening. Those positions determine which studies these entities value, and which they criticize. And they also mean that we are never likely to get the answer to the question of whether screening mammograms actually reduce the death rate from breast cancer. In light of the entrenched positions that have been taken about mammography, and given the need that any rational person would see for a better screening method, what can be done to move that agenda forward?
It’s time to recognize that we will never know, no matter how much money is spent, whether mammography is an effective screening method. So let’s spend our limited research dollars where they might do some good. Let’s stop all research on mammography screening, and devote those research dollars instead to investigations the benefits and risks of thermography, MRI, ductal lavage, and other non-radiation-based technologies that may yet prove useful for breast cancer screening.
In the meantime, what should women do about detection to improve their chances of surviving a breast cancer diagnosis?
- Remember that, although there is no guarantee that finding a tumor when it’s small will keep you from dying of breast cancer, your chances of surviving are always better when the cancer is found early than when it is found late.
- Don’t consider mammography to be synonymous with breast cancer screening. There are two other ways to “screen” for breast cancer: clinical exam and breast self-exam (BSE). BSE has come under increasing criticism because, as with mammography, there is no evidence that routine BSE saves women’s lives. But when mammograms don’t work, particularly for premenopausal women, it can hardly be a bad idea for women to know their own bodies and be vigilant about bringing any changes to the attention of a qualified health care provider.
- Acknowledge and celebrate the fact that women can and do live with ambiguity all the time, in virtually every aspect of their lives. Telling the truth about the benefits and risks of mammography screening, breast self-exam, and clinical exams will permit women to make informed choices about their health care. And since when is that a bad idea?
1 References to mammograms for “women over 50” would more accurately be made to postmenopausal women. Mammograms are thought more likely to benefit postmenopausal women because breast tissue becomes less dense after a woman stops menstruating.
2 The American Cancer Society has urged women over 40 to get mammograms for years, despite the lack of any persuasive scientific evidence that premenopausal women benefit from such screening.