High breast density is associated with a greater risk of developing breast cancer. Breast cancer in these patients are also more difficult to detect via regular screening mammograms due to lower surrounding fatty tissue.
A study that included 40,373 women aged 50 to 75 with extremely dense breasts and normal results on screening mammography was conducted in the Netherlands to investigate whether additional MRI screening would benefit these women compared to mammography alone. Participants were assigned in a 1:4 ratio, with 8061 in the MRI-invitation group and 32,312 in the mammography-only group.
Supplemental MRI screening resulted in fewer interval cancers (cancers diagnosed after normal mammogram and before the next scheduled mammogram) compared to the use of mammography alone. The rate of interval cancer detection was 2.5 per 1,000 screenings in women who had both MRI and mammograms and 5.0 per 1,000 screenings for women who had a mammogram only suggesting that the risk of interval cancer may be reduced by half.
Why it matters: Women with dense breasts have a higher risk of developing breast cancer. Additional screening for this population may increase the rate of cancer detection at earlier disease stages where the cancer is likely to be smaller and easier to treat.