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International Group Says Mammograms Of 'Limited' Value For Women In 40s

A federal health task force that has been criticized for its mammography recommendations now has scientific support from the World Health Organization.

The WHO's International Agency for Research on Cancer has just finished its review of mammography to screen for breast cancer, and it, too, concludes that the value of these screening X-rays is "limited" for women in their 40s.

That's basically what the U.S. Preventive Services Task Force decided in April, triggering howls of protest. Both reviews said there's no question that mammography benefits women in their 50s and 60s. They also agree it's not universally valuable for women in their 40s. The U.S. task force suggested that women in their 40s talk to their doctors about their individual circumstances, such as family history of breast cancer, to decide whether mammograms are appropriate for them.

That advice sounds benign, but that draft recommendation has potential financial implications. The U.S. Preventive Services Task Force's weak recommendation for women in their 40s means insurance companies and government programs won't be obligated to provide free mammograms for that age group. Insurance companies may still choose to keep covering these screening tests at no cost. Mammograms must be provided free to women 50 to 74 years old.

Motivated by the payment implications, some critics have been calling on the U.S. task force to strengthen its science-based recommendations for women in their 40s. "We know that there are women that will die if this recommendation goes through," Rep. Debbie Wasserman Schultz, D-Fla., told NPR.

But from a scientific standpoint, the U.S. task force can now point to the WHO's cancer agency for support. The IARC expert committee met in November to review the most careful research studies worldwide that evaluate the benefits and risks of mammography.

The IARC findings, published online by New England Journal of Medicine, say that there's "sufficient" evidence to say that mammography reduces breast cancer mortality in women 50 to 69 years old, but "limited" evidence that it reduces mortality among women in their 40s. That's also what IARC concluded during its last analysis, in 2002.

"We carefully reviewed the results of all available, randomized controlled trials and reaffirmed the findings from the previous evaluation of the efficacy of mammographic screening in women 50 to 69 years of age," the committee writes. "The evidence of efficacy for women in other age groups was considered inadequate."

It was a close call, though, for women in their 40s: "The vote was almost evenly divided between limited and sufficient evidence."

Both the U.S. and the international reviews balanced the benefits against the harms of mammograms. These tests do detect tumors, but most of the results are actually false alarms. Most false alarms are cleared up easily, but researchers say some women undergo surgery, radiation and drug treatment they simply don't need.

The benefits for women over 50 clearly outweigh the harms. But the IARC review didn't reach that conclusion for women under 50, where the benefit is small because breast cancer is much less common in that age group.

Radiation from the test itself can also raise the risk of breast cancer, but very slightly. The IARC put that risk at somewhere between 1 and 10 cases of breast cancer for every 100,000 women who are screened, which is "smaller by a factor of 100 than the estimates of death from breast cancer that are prevented" by mammograms. Starting mammograms in a woman's 40s increases the number of X-rays she will have in her lifetime.

The U.S. Preventive Services Task Force is now reviewing the public comments it solicited in response to its draft recommendations. It will eventually issue final recommendations (there's no specific timetable). If the science-based findings don't change, there's another option to guarantee that mammograms will be covered by insurance policies for women in their 40s. Congress can mandate that. In fact, that's the reason mammograms are guaranteed coverage right now.

Copyright 2021 NPR. To see more, visit https://www.npr.org.

Award-winning journalist Richard Harris has reported on a wide range of topics in science, medicine and the environment since he joined NPR in 1986. In early 2014, his focus shifted from an emphasis on climate change and the environment to biomedical research.
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