How does breast density on mammogram affect breast cancer risk?

Updated: Oct 17, 2016
  • Author: Nagwa Dongola, MD, FRCR; Chief Editor: Peter Eby, MD  more...
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Breast density also impacts interpretation of mammograms and the risk of developing breast cancer. Data show that the sensitivity for breast cancer detection is inversely related to density. It is as high as 98% in fatty breasts (category A) and 50-65% in dense breasts (category D). In addition, the risk of developing breast cancer increases with breast density. The relative risk of developing breast cancer in women with very dense category D breasts is 4 times greater than in women with fatty category A breasts. In the United States, 50% of women have breast density category C or D.

In the United States, there has been a political effort to make women aware of their individual breast density. Beginning in 2009 with Connecticut, 20 states now have passed legislation requiring some type of notification of patients of breast density.

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