When mammography results are negative in women with dense breast tissue, abbreviated magnetic resonance imaging is more effective than ultrasound for detecting additional early-stage breast cancers, according to interim results of a randomized trial in the United Kingdom.

Dense breast tissue increases the risk of breast cancer and decreases the sensitivity of mammography, as dense tissue may obscure small tumors. For this reason, clinicians often recommend supplemental screening with either magnetic resonance imaging (MRI) or ultrasound, although the comparative effectiveness of these methods has been unclear.

In the study, 9361 women aged 50 to 70 years with dense breasts and negative results on mammography were randomly assigned to undergo abbreviated MRI, automated whole breast ultrasound (ABUS), contrast-enhanced mammography, or no additional imaging. Among participants who underwent supplemental imaging, the cancer detection rates were 4.2 per 1000 examinations for ABUS, 17.4 per 1000 for abbreviated MRI, and 19.2 per 1000 for contrast-enhanced mammography.

The authors noted that although supplemental imaging can detect additional small and potentially invasive tumors, further research is needed to determine whether early detection in this setting improves breast cancer–specific mortality. They also emphasized the need for longer-term data to assess overdiagnosis and to inform cost-benefit analyses for population-wide implementation.

Source: The Lancet