A large national study has found that the rate of women undergoing magnetic resonance imaging (MRI) of the breast nearly tripled from 2005 to 2009: from four to 11 examinations per 1,000 women. The study appeared with a report of breast MRI use in the Northeast, and an editorial accompanied the two studies.

“Ours is the first large-scale report of how women are actually using breast MRI in national community practice,” said lead author Karen Wernli, PhD, an assistant investigator at Group Health Research Institute in Seattle, Washington. This community-based reporting is made possible by the Breast Cancer Surveillance Consortium (BCSC), the nation’s largest and most comprehensive collection of information on screening for breast cancer, funded by the National Cancer Institute (NCI). These studies were published in JAMA Internal Medicine (2013; doi:10.1001/jamainternmed.2013.11963; doi:10.1001/jamainternmed.2013.11958).

Breast MRI is recommended in addition to mammography to screen women at high risk (20% to 25% or more) for developing breast cancer during their lifetime. Among women in the study screened with breast MRI, the proportion at high lifetime risk for breast cancer rose from 9% in 2005 to 29% in 2009.

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“We found that use of breast MRI for breast cancer screening—rather than diagnosis—is rising, as is appropriate,” said Wernli. During the study period, use of MRI for diagnosis decreased, and use for screening increased. Screening is done routinely in the absence of suspicion, and diagnostic evaluation is the workup after other breast imaging, such as mammography or ultrasound. Diagnostic evaluation with breast MRI, in particular to avoid a biopsy, is not recommended before breast cancer is diagnosed. After a diagnosis, some people use breast MRI to evaluate for staging and extent of disease.

Despite their disparate methods and populations, both studies reported similar findings: Breast MRI is now being used for screening more often than for diagnosis; and its use for screening is more common in average-risk women than in higher-risk women—but that pattern is improving.

“Our study suggests breast MRI is being used better,” Wernli said. But the study also showed that greater improvement is needed in appropriately using breast MRI for risk-based screening. The vast majority of women at high lifetime risk for breast cancer—who could most likely benefit from breast MRI—appeared not to undergo breast MRI yet, instead using only mammography for screening. Meanwhile, many women at average risk for breast cancer were screened using breast MRI, even though mammography is still considered the best screening test for them.

“To prevent the underuse by women at high risk, and overuse by those at average risk,” Wernli said, “we need to strengthen the network of providers, like genetic counselors, who can provide women with the breast cancer risk counseling that they need.”