Why Are Mammogram Guidelines Conflicting?

When women are fully informed about the risks and benefits of mammograms, 70 percent may choose not to get screened. You may be in that 30 percent who opts to get a mammogram and absolutely have the right to decide for yourself.

“For nearly a century, public health organizations, professional associations, patient advocacy groups, academics, and clinicians largely viewed cancer screening as a simple, safe way to save lives.” But these days, even though we’re all looking at the same body of evidence, “differing interpretations about evidence on benefits and harms of screening mammography has led to conflicting recommendations…that range from intensive screening starting at age 40 to no screening at all.” Currently, the four main groups in the United States charged with making mammogram recommendations—the American Cancer Society, the U.S. Preventive Services Task Force, the American College of Obstetricians and Gynecologists, and the National Comprehensive Cancer Network—each set contradictory guidelines. What’s a woman to do? This is the issue I discuss in my video Mammogram Recommendations: Why the Conflicting Guidelines?.

Guidelines are based on systematic reviews of the evidence. “In the last 15 years, 50 systematic reviews on the use of routine mammography for breast cancer screening in asymptomatic women have been published but a consistent conclusion has not emerged.” Why? It turns out that the conclusions of systematic reviews may have been influenced by competing conflicts of interests of the authors.

“It is only in health care, after all, that the same group that provides a service also tells us how valuable that service is and how much of it we need…We must acknowledge that just as in any other profession or industry, self-interest is unavoidably at work in health care.” Indeed, an analysis of more than a hundred papers concluded: “Scientific articles tend to emphasize the major benefits of mammography screening over its major harms. This imbalance is related to the authors’ affiliation.”

It may be no coincidence that all of the expert panels that have come out against routine mammograms excluded radiologists. Perhaps those who depend on mammograms for their paycheck might be more likely to recommend them. One “leading proponent of mammography screening said ‘I earn my living reading mammograms’, and ‘if you don’t have a conflict of interest you probably don’t have the expertise’.” He accused the breast cancer screening panels of injecting their own biases. “In this debate, there are armies of the faithful, and only a disappointing scattering of moderators and peacemakers.”

Some have even suggested that “this debate should not be taking place in public…Such paternalism assumes that women cannot decide for themselves whether the available evidence supports or refutes the case for mammography. Discouraging a discussion with women about the evidence for and against mammography is more harmful for women’s health, not less, if doctors truly believe that patients should be active partners in making decisions about their care.”

If you read the actual studies, you can determine whether the investigators declare any conflicts of interest, but if you simply hear about the studies second-hand, you may have no idea. Until the developers of screening guidelines “emphasize evidence over commercial or financial interests,” we all have to take personal responsibility to become informed consumers.

It would be nice to be able to trust cancer charities, but it is “virtually impossible” for such organizations to remain strictly “evidence-based” when they must rely on donors “for their very existence.” To his credit, the Chief Medical Officer of the American Cancer Society (ACS) “noted that we need to be true to the science”—but he was talking about prostate cancer screening. Although the ACS simply tells women to get mammograms, it lets men decide for themselves. The charity is open about the harms of prostate cancer screening, but “very little transparent ‘educational’ information about the harms of mammography is provided on the American Cancer Society website.”

“In the United States…a double standard exists: women are encouraged to participate in screening mammography”—to just do it—“while men are advised to make informed decisions regarding prostate screening, although the fundamental issues to consider are very similar.”

The “dissimilarity” in how organizations like the American Cancer Society “view the shared decision making of women contemplating breast cancer screening versus that of men contemplating prostate cancer screening, couldn’t be clearer. Do [they] believe that men can handle uncertainties regarding screening tests for prostate cancer, but that women cannot handle uncertainties, and in fact become confused by them when making decisions about breast cancer screenings?” Men get to “make informed decisions,” but women are merely “summoned.”

The bottom line is that there is “more than one right answer” to the question, “Should I be screened for breast cancer?” My goal is to enable you to make the decision that is right for you and your loved ones. One survey found that “if women knew how small the real effectiveness of breast cancer screening in preventing breast cancer deaths is, 70% said they would not submit to it.” But, you may be in that 30 percent—and you have every right to decide for yourself.

When it comes to this topic, there’s just so much confusion, combined with the corrupting commercial interests of a billion–dollar industry. As with any important health decision, everyone should be fully informed of the risks and benefits, and make up their own mind about their own bodies.

KEY TAKEAWAYS

At present, the American Cancer Society, the U.S. Preventive Services Task Force, the American College of Obstetricians and Gynecologists, and the National Comprehensive Cancer Network have each set contradictory guidelines regarding mammography screening.
Conclusions of systematic reviews on the use of routine mammograms for breast cancer screening in asymptomatic women have been inconsistent, and the evidence may be influenced by competing conflicts of interests of the authors.
An analysis of more than a hundred papers concluded: “Scientific articles tend to emphasize the major benefits of mammography screening over its major harms. This imbalance is related to the authors’ affiliation.”
Cancer charities may also be challenged with remaining strictly “evidence-based” when they rely on donations to exist.
A double standard exists in the United States where women are encouraged to get routine mammograms, while men are advised to make informed decisions about prostate screening even though the fundamental issues to consider are quite similar.
A survey found that “if women knew how small the real effectiveness of breast cancer screening in preventing breast cancer deaths is, 70% said they would not submit to it.” You may be in that 30 percent who opts to get a mammogram, and you have every right to decide for yourself.

This is the second in a 14-part series on mammograms, which started with Nine out of Ten Women Misinformed About Mammograms. The following videos complete the series:

For more on breast cancer, see:

I was able to cover colon cancer screening in just one video. If you missed it, check out Should We All Get Colonoscopies Starting at Age 50?.

Also on the topic of medical screenings, see Is It Worth Getting Annual Health Check-Ups? and Is It Worth Getting an Annual Physical Exam?.

In health,

Michael Greger, M.D.

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