Mammographic Breast Density – Position Statement

Breast density is a mammographic description of the fibroglandular (structural and milk-producing) tissues of the breast. These tissues appear white or ‘dense’ on the mammogram compared with the fatty or ‘grey’ background. Mammographic density is associated with 2 significant risks. Research shows that the greater the density the greater the risk of developing breast cancer and the greater the risk that a breast cancer will be missed on a mammogram (false negative diagnosis).

The cancer risk associated with increased density has been frequently reported since the 1970’s but was highlighted by a large 2007 Canadian mammographic screening program study that showed that women with the highest density (>75% area) had nearly 5 times the cancer rate of women with the lowest density (<10% area). In the same study the highest density group women had nearly 18 times the risk of a cancer being diagnosed within the 12 months after their screening mammogram, mainly due to the cancer being missed on the screening mammogram.

Around 40% of women aged over 40 years have high mammographic density. Women should be informed of their mammographic density and are entitled to know of the associated risks. Better breast cancer screening is needed for women with dense breasts. Like all medicine, screening is moving away from a one-size-fits-all model towards a personalised approach based on data analytics and a patient centered care experience. Research shows that screening women at increased risk with additional imaging such as 3D mammography (tomography), ultrasound examination and MRI can improve early cancer detection.