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About Breast Density

Every woman who gets a mammogram at Legacy Health will get information about their breast density in their mammogram results letter. Women with "extremely dense" breast tissue may be at higher risk for breast cancer. Below is information designed to help you understand this information.

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    The Oregon law

    The Oregon state law, SB 420, requires that after a mammogram women be told if they have "extremely dense" breast tisue and about options for extra testing.

    At Legacy

    After your mammogram, you will receive a letter with the results of your mammogram, and information about the density of your breast tissue.

    If you do have dense or extremely dense breasts, your letter will also explain the risks of breast cancer and what to do. It will explain that:

    • Dense breasts make it harder to see small growths, which may be breast cancer.
    • Women with dense breasts may want to have more tests.
    • You should talk to your doctor about this.


    If you do not have dense breasts, your letter from Legacy will simply tell you the density of your breast tissue.

    What is breast density?

    Breast density is the percentage of fibrous and glandular tissue in the breast. The higher the percentage of this type of tissue, the more "dense" the breast. All types are normal. The four types of breast tissue are:

    Fatty (not dense): The breast is mostly fat (75 percent or more of the tissue). There is no added risk of breast cancer.

    Scattered fibroglandular densities (not dense): The breast is mostly fat (50–75 percent). There is no added risk of breast cancer.

    Heterogenously dense: 51 to 75 percent of the breast is dense tissue (not fat). It can be harder to see small lumps or tumors. This means a very slight added risk of breast cancer.

    Extremely dense: More than 75 percent of the breast is dense tissue (not fat). This can lead to missing some cancers. Extremely dense breast tissue doubles the risk of breast cancer. This risk is similar to the risk of having a family history of breast cancer (mother, sister or daughter with cancer in one breast, after menopause).

    My letter says I don't have dense breasts. Do I still need to get a mammogram?

    Yes. It doesn't matter whether you have dense breasts or not, you should get a mammogram every year starting at age 40. Legacy Cancer Institute, the American Cancer Society and the American College of Obstetrics and Gynecology all say women should have an annual mammogram starting at age 40.

    My letter says that I have heterogenously or extremely dense breasts. Do I need extra tests?

    Most likely not, especially if you have "heterogenously dense" breasts.

    If you had your mammogram at a Legacy Breast Health Center, you had a "3-D" mammogram. The 3-D screening is one of the best tools to find breast cancer — it increases the mammogram's accuracy by about as much as having a mammogram plus an ultrasound. This means you may not need extra testing. You should discuss your personal situation with your doctor.


    If you have a close family member (mother, sister, daughter) who had breast or ovarian cancer before menopause, or a male family member with breast cancer, it is probably a good idea to meet with a genetics counselor for a risk assessment. Legacy Genetics Services can help: Call 503-413-6534 for an appointment.


    If you do not have a close family member with one of those cancers, your risk is low. Talk to your doctor about whether you should have more tests. You should know that insurance doesn't cover more tests unless you are at high risk.

    My letter says that I have heterogenously or extremely dense breasts. Do I need to be screened with something other than mammography?

    No.  Nothing is better than a mammogram for looking for breast cancer. This is because some kinds of masses only show up on a mammogram. The other tests are in addition to a regular mammogram, not instead of a mammogram.

    My letter lists additional screening options: MRI, ultrasound and BSGI. What is BSGI?

    BSGI is a test used to confirm whether someone has breast cancer. It is not recommended for screening. Your doctor will discuss it with you if it is needed in your case.