Breast Screening - Risk Adaptive Imaging for Density

Breast density is a measure of the amount of fibroglandular tissue and is a risk factor for breast cancer. Women with extremely dense breasts are at 4-fold increased breast cancer risk compared to women with 'fatty' breasts. High breast density reduces the sensitivity of mammography increasing the probability of the test missing a cancer. Women with dense breasts have their cancers found when the cancer is larger as they present with interval cancers or their cancers are not detected until the next screening round at a later stage. The UK national breast screening programme (NHS BSP) offers all women aged 50-70 screening with 3-yearly mammograms. It aims to reduce breast cancer mortality by 20% by detecting small cancers thereby reducing the number of late stage diagnoses. However only 53% of the cancers being detected are small (\<15mm). This is partly due to masking of cancers by dense breast tissue. This trial addresses how best to screen women with dense breasts for breast cancer. BRAID will randomise women whose recent screening normal mammogram shows that they have dense breasts to either standard of care (no supplementary imaging) or supplementary imaging with abbreviated MRI (ABB-MRI), automated whole breast ultrasound (ABUS) or contrast enhanced spectral mammography (CEM). These imaging techniques have been shown to be more sensitive than mammography at detecting cancers in dense breast tissue. Our hypothesis is that more cancers will be detected at an earlier stage with supplemental imaging.