Annual screening mammography adds no value to women who are high risk for breast cancer and, as a matter of course, are already getting screened each year with breast MRI, according to a study conducted at the University of Toronto and published online June 6 in Radiology.

Glen Lo, MBBS, Pavel Crystal, MD, and colleagues reviewed the outcomes of 3,934 screening breast studies (1,977 breast MRIs and 1,957 mammograms) performed at three academic hospitals on 1,249 high-risk women (mean age 44 years; range, 14 to 72 years) over a two-and-a-half-year period ending in July 2014.

Indicators of elevated risk included high-risk family history, BRCA mutation carriers, past mantle radiation therapy and prior history of breast or ovarian cancer.

The team found that no cancers were visible at screening mammography that were not detected with screening MRI.

In addition, the cancer detection rate for MRI was 21.8 cancers per 1,000 exams versus 7.2 cancers per 1,000 mammograms, and MRI sensitivity topped that of mammography 96 percent to 31 percent.

MRI also had a better benign breast biopsy rate than mammography (63.9 percent vs. 70.8 percent).

Screening mammography did beat screening breast MRI on specificity, 89 percent vs. 78 percent, and on false-positive rate, 10.4 percent vs. 21.1 percent. However, the authors note, the specificity rates they found are similar to those previously reported in studies that assigned BI-RADS 3—probably benign—interpretations as positive screening cases.

In their discussion the authors point out that breast MRI is currently recommended only as an adjunct to mammography.

That recommendation needs to be rethought, they state.

“Since mammography is associated with substantial false-positive rate (albeit lower than MR imaging), anxiety, radiation exposure and costs, we believe that current guidelines for screening high-risk women need to be modified,” they write. “We suggest considering using MR imaging as a stand-alone screening test and diminish the use of mammography in screening of high-risk young women who qualify for annual screening breast MR imaging, although additional studies are needed to validate our results.”