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Breast density and screening for breast cancer

Phoebe E Freer, MD
Priscilla J Slanetz, MD, MPH, FACR
Section Editor
Joann G Elmore, MD, MPH
Deputy Editor
Sadhna R Vora, MD


Increased breast density impairs the detection of abnormalities on mammography and increases the risk for breast cancer. Passage of legislation in multiple states in the United States regarding mammogram reporting of breast density and follow-up for women with dense breasts has led to renewed discussion about the optimal screening protocol for early detection of breast cancer in women who have dense breast tissue on mammography [1,2].

This topic will discuss the classification of breast density and indications for supplemental testing. Screening for breast cancer and breast imaging are discussed elsewhere. (See "Screening for breast cancer: Strategies and recommendations" and "Screening for breast cancer: Evidence for effectiveness and harms" and "Breast imaging for cancer screening: Mammography and ultrasonography".)


Breast tissue comprises skin, blood vessels, ductal and stromal elements of the glands (which appear radio-opaque or white on mammography), and fat (which appears radiolucent or black on mammography). Mammographic breast density is defined as the relative amount of radio-opaque (white) elements to radiolucent (black) fat on the image. Increase in the proportion of radio-opaque elements leads to greater mammographic breast density.

Increased breast density may obscure the detection of a benign mass or, more importantly, a breast cancer. Reduced sensitivity of mammography in younger women in part is related to increased mammographic density due to a higher proportion of breast epithelial and stromal elements in younger breasts [3].

Breast density does not correlate with physical exam findings [4,5]. Breast density is a radiologic finding and cannot be predicted without obtaining a mammogram [6,7].

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Literature review current through: Nov 2017. | This topic last updated: Nov 16, 2016.
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