Can MRI spot breast cancers that mammography may miss?

Netherlands: It is already known that extremely dense breast tissue is a risk factor for breast cancer and limits the detection of cancer with mammography. Now, a recent study has found that supplemental MRI screening in women with extremely dense breast tissues and normal results on mammography lowers the diagnosis of interval cancers -- cancer that occurs between mammography screenings -- than mammography alone during a screening period of 2 years. However, MRI screening resulted in a higher rate of false-positive results compared to mammography.

These are the results of the DENSE trial published in The New England Journal of Medicine.

This study "is a first important step towards evidence for supplemental screening for MRI, but there are still questions to be answered and benefits and harms that need to be carefully balanced," wrote the authors.

This multicenter, randomized, controlled trial was conducted in the Netherlands. 40,373 women between the ages of 50 and 75 years with extremely dense breast tissue and normal results on screening mammography, were assigned to a group that was invited to undergo supplemental MRI or to a group that received mammography screening only. The groups were assigned in the ratio of 1:4 with 8061 in the MRI-invitation group and 32,312 in the mammography-only group.

The primary outcome was the between-group difference in the incidence of interval cancers during a 2-year screening period.

Read Also: Ultrasound after mammography effective way for dense breast screening, reveals study

Key findings of the study include:

• The interval-cancer rate was 2.5 per 1000 screenings in the MRI-invitation group and 5.0 per 1000 screenings in the mammography-only group, for a difference of 2.5 per 1000 screenings.


• Of the women who were invited to undergo MRI, 59% accepted the invitation.


• Of the 20 interval cancers that were diagnosed in the MRI-invitation group, 4 were diagnosed in the women who actually underwent MRI (0.8 per 1000 screenings) and 16 in those who did not accept the invitation (4.9 per 1000 screenings).


• The MRI cancer-detection rate among the women who actually underwent MRI screening was 16.5 per 1000 screenings.


• The positive predictive value was 17.4% for recall for additional testing and 26.3% for biopsy.


• The false-positive rate was 79.8 per 1000 screenings.


• Among the women who underwent MRI, 0.1% had either an adverse event or a serious adverse event during or immediately after the screening.

The study, "Supplemental MRI Screening for Women with Extremely Dense Breast Tissue," is published in the New England Journal of Medicine.

DOI: 10.1056/NEJMoa190398