For women at high risk of breast cancer, the new American Cancer Society guidelines recommend annual magnetic resonance imaging (MRI) exams, not just annual mammograms.
This advice could apply to more than one million women.
Robert Smith, an epidemiologist with the American Cancer Society, said, "These are going to be women with two or more close relatives ... who've been diagnosed with breast or ovarian cancer — [it] may be [a] mother or maternal aunt, paternal aunt or grandmother. [These women] may have had one to two relatives diagnosed pre-menopausally."
Women can also undergo genetic testing to see whether they have a defective gene that puts them at very high risk for breast cancer. It's recommended these women also get yearly MRI scans. The guidelines also apply to women who were exposed to radiation between the ages of 12 and 18 — that's mostly women who were treated for Hodgkins disease.
Smith said the recommendations came after a series of studies showed MRI exams to be more effective than mammograms at finding cancer in this population of women.
One of those studies, published Wednesday in The New England Journal of Medicine, showed that MRI caught tumors that mammograms missed. The study looked at women who had just been diagnosed with breast cancer in one breast — and their "healthy" breast had already been through a mammogram.
Radiologist Connie Lehman is a breast-imaging specialist at the University of Washington Medical Center, who conducted the study of 969 women featured in The New England Journal of Medicine article.
Lehman said mammography measures breast density and tissue distortion. But the MRI is more precise.
"MR uses strong magnets, radio waves, computers to produce images of what is occurring in the breast tissue," she said. "And most importantly, how blood flow is behaving."
Areas with increased blood flow can mean cancer cells are flourishing.
"We ... performed MRI to see if we could find a cancer even though there was basically a 'clean bill of health' from mammogram and clinical breast exam," she said.
After the MRI, Lehman found cancer in 30 women. That's 3 percent of the women in the study. That represents 10 times more cancer found than would be found by mammogram.
"Rather than have surgery, possibly radiation and chemo for known cancer, only then to be told one, two, five years later that their cancer has been found in the opposite breast — this enabled the women to have a full diagnosis of the cancers in both breasts at the same time, consolidating their treatment into one round of therapy," she said.
And for women who were considering double mastectomies as a preventive measure, if the MRI found no cancer in the second breast, that could be reassuring information that could influence their decision, Lehman said.
Researchers emphasize that for most women, a yearly mammogram will detect cancer. Because MRI is so sensitive, it can lead to false-positives that lead women who don't have cancer to undergo biopsy.
MRI scans are expensive — about $1,000. Most insurers review scientific evidence when deciding what to pay for, and Smith expects most insurers to cover the cost for women at high risk of breast cancer.
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