Unintended consequences

Do MRIs lead to unnecessary mastectomies?

“Our ability to devise new tests has greatly outpaced our ability to tell whether they’re helpful,” says Cary Gross, associate professor at the Yale School of Medicine. A case in point: breast cancer patients are increasingly likely to get MRIs, and increasingly likely to undergo aggressive surgery—but no one knows whether they are better off for it.

Gross, who directs Yale’s Cancer Outcomes, Public Policy, and Effectiveness Research Center (COPPER), is lead author of a new study that examines the use of magnetic resonance imaging, or MRIs—and the corresponding growth in aggressive surgery—among older women.

The study’s MRI numbers are startling: among breast cancer patients age 67 and over, use of the scans increased from 0.8 percent in 2000–01 to 25.2 percent in 2008–09. After adjusting for patient demographics and cancer characteristics, the researchers found that patients who received MRIs had 21 percent higher odds of undergoing mastectomies instead of breast-conserving surgery. More starkly, MRI patients had nearly twice the odds of having both breasts removed. When cancer was found in only one breast, women who got MRIs had 2.5 times the odds of receiving double mastectomies. 

“Those are very invasive surgeries,” Gross says. “By getting women an MRI,” which detects tiny abnormalities, “we’re leading women down a path to more aggressive surgery with more complications.” (The study, in Breast Cancer Research and Treatment, examines Medicare data for more than 72,000 patients.) He adds: “We’re not saying MRIs are good or MRIs are bad; we just don’t know.” Next up, he says: research to determine whether MRIs produce better outcomes.

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