That mammograms aren't perfect is old news. What is news, according to this panel, is that they've identified the age where science shows that the benefits of mammograms outweigh the risks. The main issues, according to the Task Force paper, are that false positive results lead to unnecessary follow-up mammograms and breast biopsies, as well as the stress associated with those procedures.
Another possibility, especially for women in their 60s, is overdiagnosis--detecting a cancer that would otherwise have never been symptomatic or life-threatening--and the treatment (surgery, chemo, radiation, etc.) that comes with it. Some experts also believe that cumulative exposure to radiation from annual mammograms (the x-ray gives off low levels) could cause health problems, including cancer, but others say this risk is small and largely theoretical.
Perhaps most troublesome is that mammograms aren't lifesaving for all women, though many people assume they are. Statistics vary, but at best, they only reduce the risk of dying from breast cancer by up to 20 percent.
"We've made it sound like every cancer can be found early and cured, and that's not true," says Love. Mammograms miss many cancers, particularly the fast-growing, aggressive ones that are most likely to strike women under age 50. "Mammograms are best at finding the slow-growing, low-grade cancers, not the worst ones," she says.
Why do other groups disagree with the new guidelines?
Medical organizations such as the American Cancer Society, the American College of Obstetricians and Gynecologists, the American College of Radiologists, and others have all said that women should stick to current recommendations of annual mammograms starting at age 40.
"The fact is, there are conflicting guidelines out there, and they're all based on the exact same data, but it's how we each interpret that data," says Carole Lee, MD, chair of the commission on breast imaging of the American College of Radiology and an attending radiologist at Sloan-Kettering Memorial Cancer Center in New York City.
Most of the groups that do not support the new guidelines are clinicians on the front line, who treat women with cancer and see fewer of them dying because of early detection, says Bevers. (M.D. Anderson also maintains annual screenings for women 40 and older). "Although the net benefit of saving lives through mammograms is small, it's still saving lives," she says. "I don't think it's fair to compare the anxiety of a false-positive test result with a woman dying of breast cancer." If you go for yearly screenings, recognize the risk: that you may have an abnormal result and need a biopsy, says Lee. "I think most of us would gladly accept that tradeoff in exchange for the possibility of a cancer being found early."
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