When the researchers looked at these eight trials individually, none of them showed a benefit from mammography, Nelson says. It was only when the trial data were pooled that a benefit emerged — a 15% reduction in the risk of dying of breast cancer. Though that sounds "pretty respectable," she says, it's actually quite modest because the number of women who die of breast cancer in their 40s is tiny.
To some people, the main problem with the task force recommendations wasn't the lack of support for widespread mammography for women in their 40s but the lack of guidance about how doctors could explain the uncertain medical evidence to their patients and help them make an informed decision.
After all, if a group of experts who had the time to plow through mountains of studies couldn't come to a consensus about whether these women should have routine mammograms, how were women and their doctors supposed to make an evidence-based decision?
"What they said is, 'We're in the era of personalized care — go to your doctor and personalize your own care,'" says oncologist Marissa Weiss, founder of the advocacy group Breastcancer.org. "But the fact is, most doctors don't have the skills to do this."
Nor, she adds, do patients.
"To tell women to make an intelligent, informed decision about mammography is irresponsible," Weiss says. "None of us know enough to accurately assess risk and identify who does and does not benefit from mammography."
But the decision doesn't boil down to math, since both the benefits and the risks are modest, counters Dr. H. Gilbert Welch, an expert on cancer screening at the Dartmouth Institute for Health Policy and Clinical Practice in Lebanon, N.H., and author of "Overdiagnosed: Making People Sick in the Pursuit of Health."
"There's no algebra to solve it," he says. Instead, what matters is the value each woman places on the variables in the equation. "Some women will dismiss the harms as being trivial — and that's fine. Others will decide that the benefit is too rare and they don't want to go through the much larger risk of being medicalized and going through procedures they don't enjoy."
Shared decision-making may sound good in theory, but in practice it's not always popular, says Dr. Cheryl Iglesia, chairwoman of the American Congress of Obstetricians and Gynecologists' committee on gynecologic practice. "A lot of patients say, 'Well, doctor, I don't know what to do. You're the doctor. You tell me.'"
Iglesia, for one, simply fell back on the ACOG guidelines when dispensing advice to patients: These still call for annual or biennial mammograms for women in their 40s.
So what are women choosing? The journal Annals of Internal Medicine conducted an online poll last year about the new recommendations, and of the roughly 240 women who participated, 71% said they would continue to get regular mammograms in their 40s — even if their doctors recommended against them. Fewer than 20% planned to wait until age 50 for their first mammogram. While this poll does not reflect the thinking of women as a whole (since those with passionate feelings were probably more likely to respond), it does provide a snapshot of the continued struggle to make sense of the guidelines.
Of the more than 400 healthcare providers who also took the poll, slightly more than half said the recommendations would change how they advise their patients about breast cancer screening. Two-thirds said they would stop offering routine mammograms to women in their 40s.
Lost in the bickering over the guidelines for 40-somethings is the fact that there's widespread agreement about most everything else, says Dr. Otis W. Brawley, chief medical officer of the American Cancer Society.
"We all agree that mammography saves lives, we all agree on the magnitude of lives saved, and we all agree there are drawbacks and benefits," he says. While the debate about women in their 40s rages on, he adds, "nearly 20,000 women in their 50s and 60s die over a 10-year period because they don't get a mammogram, when we all agree they should."