Early detection of breast cancer with MRI in women with extremely dense breasts

In the Dutch breast cancer screening program, all women aged 50 to 75 years are invited for mammography screening biennially. Yearly, approximately 1 million screening examinations are performed in the screening program.
Approximately 8% of the Dutch screening participants has extremely dense breasts, which is a high amount of fibroglandular tissue in the breast.
Women with extremely dense breasts have a two-fold higher breast cancer risk than women with average breast density. Breast cancers are more difficult to detect on mammography in dense breast tissue.
In the DENSE-trial the additional value of supplemental MRI in women with extremely dense breasts is studied. The trial is embedded in the Dutch population-based breast cancer screening program. Between 2011 and 2015, 8061 women were invited for supplemental MRI-screening, and 4783 women actually participated in MRI screening.
The first results of the DENSE-trial show that in every 1000 women with extremely dense breasts, 17 breast cancers were detected with MRI. The mammograms of these women were normal. In addition, less women were diagnosed with breast cancer in between two screening rounds: the first results of the DENSE trial showed a significant reduction of interval cancers in women with extremely dense breasts who were offered
supplemental MRI screening.
Not all invited women were willing to participate in supplemental MRI-screening. Frequently stated reasons for nonparticipation were related to the MRI-examination (for example claustrophobia) or to anxiety for the screening outcome.
Supplemental MRI-screening also has disadvantages, for example it can lead to stress and unnecessary referrals.
The desirability of supplemental MRI-screening still has to be determined.