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  • Breast Density on a Mammogram



    Breast Density
    Fact Sheet


    Questions to Ask Your Doctor about Breast Density
    Fact Sheet

    What is breast density?

    Breast density is a measure used to describe the proportion of the different tissues that make up a woman’s breasts. Breasts are made up of fat and breast tissue (the milk ducts and lobules, which may be called glandular tissue). Connective tissue helps hold everything place. Learn more about the anatomy and structure of the breasts.

    Breast density is not a measure of how the breasts feel, but rather how the breasts look on a mammogram. It compares the area of breast and connective tissue seen on a mammogram to the area of fat. Breast and connective tissue are denser than fat and this difference shows up on a mammogram (see images below).

    • High breast density means there is a greater amount of breast and connective tissue compared to fat.
    • Low breast density means there is a greater amount of fat compared to breast and connective tissue.

    How does dense breast tissue look on a mammogram?

    These mammogram images show a range of breast density. Some breasts are mostly fat (fatty breast) and some breasts are mostly breast and connective tissue (dense breast). 

    Breast density images without text

                                       Fatty breast                      Some breast density          More breast density        Dense breast

    Mammograms of dense breasts are harder to read than mammograms of fatty breasts.

    Learn more about the anatomy of the breast.

    Breast density and breast cancer risk

    Women with high breast density are four to five times more likely to get breast cancer than women with low breast density [59-60].  

    Komen Perspectives

     Read our perspective on breast density and breast cancer risk
    (August 2011).*


    How do health care providers use breast density?

    At this time, health care providers do not routinely use a woman's breast density to assess her breast cancer risk. This is mainly due to the lack of a standard measure of breast density. While a measure of breast density may be recorded on a mammography report, this measure is not used to assess risk.

    However, by looking at your mammogram or the measure of breast density, your provider may conclude that you have dense breasts and may suggest other types of breast imaging.

    Some states in the U.S. now have laws requiring that women found to have dense breasts on a mammogram are sent a letter with this information. Although this information may seem helpful, currently there are no special recommendations or screening guidelines for women with dense breasts. In addition, although women with dense breasts appear to be at higher risk of breast cancer, it is not clear that lowering breast density will decrease risk. For example, getting older and gaining weight after menopause are both related to a decrease in breast density, but are also related to an increase in breast cancer risk.

    If you have any concerns about your breast density, talk to your provider.

    Learn more about breast density and mammography.  

     Komen’s statement on breast density legislation

    Susan G. Komen endorses federal legislation requiring mammography centers to report breast density information to physicians and patients (the “Breast Density and Mammography Reporting Act of 2014”). Komen believes this legislation will improve the written mammography results providers send to patients. It requires the U.S. Food and Drug Administration (FDA) to consult with leading cancer organizations (including Komen) in the development of standard wording for these patient reports. The legislation also directs the U.S. Department of Health and Human Services to focus research on improving breast cancer screening methods.

    Screening for women with dense breasts

    At this time, there are no special recommendations or screening guidelines for women with dense breasts. Digital mammography may offer screening benefits over film mammography for women with dense breasts [61]. Most mammography centers now use digital mammography to screen all women.

    Breast ultrasound and breast MRI

    Breast ultrasound and breast MRI (each in combination with mammography) are being studied to learn whether they improve detection in women with dense breasts compared to mammography alone.

    Learn more about breast ultrasound and breast MRI.

    Learn more about screening for women at higher risk of breast cancer.

    *Please note, the information provided within Komen Perspectives articles is only current as of the date of posting. Therefore, some information may be out of date at this time.

    Updated 11/05/14

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