New Meta-Analysis Says MRI is Best Supplemental Imaging for Dense Breasts

For women with dense breasts who have average or intermediate risk for breast cancer, magnetic resonance imaging (MRI) is the superior supplemental imaging option, according to a new meta-analysis.

Noting a 47 prevalence of dense breasts in the United States screening population, a four- to sixfold higher breast cancer risk in women with extremely dense breasts and challenges with overlapping fibroglandular tissue on mammography in this population, researchers examined the literature on supplemental breast cancer screening modalities.

In their review of 22 studies and data from a total of 132,166 women with dense breasts and negative mammography findings, the study authors found that MRI had a 1.54 incremental cancer detection (IDR) rate per 1,000 screenings in comparison to IDR rates of -0.35 for handheld ultrasound, -0.14 for digital breast tomosynthesis and -0.26 for automated whole breast ultrasound. The researchers also emphasized MRI’s superior cancer detection rates (CDRs) for invasive breast cancer (1.31) and ductal carcinoma in situ (1.91).

“Our results confirm the expected higher CDR of breast MRI as an adjunct breast screening modality in women with dense breasts and mammography negative for cancer, which has been widely documented in the high-risk population,” wrote Vivianne Freitas, M.D., MSc, an assistant professor of radiology at the University of Toronto, and colleagues. “The results of our study also comply with previously published studies that demonstrated the benefit of MRI in detecting breast cancer in a population at intermediate risk, including those with a personal history of breast cancer.”

(Editor’s note: For related content, see “What a New Study Reveals About Breast Density Awareness” and “What BI-RADS Changes Are on the Way for Breast MRI Reporting?”)

While the meta-analysis noted no statistically significant differences for MRI in regard to positive predictive value for recall (PPV1) or biopsies (PPV3), the study authors said there were fewer MRI studies in the meta-analysis and noted that the PPVs for MRI were generally higher than those for handheld ultrasound and automated whole breast ultrasound.

“This may represent another important benefit of MRI in this setting because higher false-positive rates increase patient anxiety and the cost burden on the health-care system from additional imaging workup, short interval follow-up or biopsy,” maintained Freitas and colleagues.

In order to reduce possible confounders that may contribute to selection bias, the study authors excluded retrospective studies but conceded this may have limited the statistical power of the meta-analysis. They also acknowledged that subjective visual assessment of breast density occurred in most of the reviewed studies.