From the Breast Diaries:

What Breast Density Means to You

Breast density is one of the strongest predictors of the failure of mammography to detect cancer. About half of women younger than 50 are dense, and 1/3 of women over 50 are dense. That’s a large number of women for whom mammography alone is not enough. Up to half of breast cancers cannot be seen on the mammogram in women with dense breasts. This leads to missed cancers that are discovered at later stages, resulting in more invasive treatments and a poorer prognosis. 40,000 women in the U.S. die each year from breast cancer. Some of these women had dense breasts and didn’t know it; even though they went for mammograms every year, by the time their cancers were found it was too late. A wonderful grass-roots organization has been founded by patients personally affected by this lack of information (, and they are doing everything they can to address this issue for all women. Because of their advocacy, laws have recently been passed in Connecticut and Texas, requiring that women be informed of their density when they have a mammogram, and that their insurance company must cover the cost of an additional screening test if they are dense. Bills are also being considered in New York and California, as well as at a federal level.

Density is determined by a mammogram. It cannot be determined with physical exam. Dense breasts have more fibrous and glandular tissue (which appears white on the films and can hide cancers, which also appear white), while breasts that are NOT dense have more fatty tissue (which appears grey and is easy to see through on the mammogram).

This is a mammogram view from a woman with fatty breasts that are NOT dense. The radiologist can state with a high level of confidence that there is no cancer in this breast:

This patient has breasts that would be categorized as “scattered fibroglandular tissue”. As you can see, there is some dense white tissue on this film where cancers can potentially hide, but much of the breast is fatty and easy to see through:

Now we start getting into the dense breasts. This patient has “heterogeneously dense” breast tissue, which means that more than half of the tissue in her breast is dense. The ability for a mammogram to find cancer in this breast is compromised, and the patient should be sent for a breast ultrasound or MRI in addition to an annual mammogram:


Here are two patients with “extremely dense” breasts. More than 75% of their tissue is dense, severely limiting the ability of mammography to find an early cancer. Women with breasts that are this dense also have a 5x greater risk of developing breast cancer compared to women with fatty (non-dense) breasts. These women should definitely be having annual breast ultrasound or MRI in addition to their yearly mammogram:

Don’t be surprised if your doctor does not know much about breast density. As the issue gains traction, the medical community will become more informed over time. For now, it is up to you to find out if your breasts are dense so you can protect yourself from advanced cancer.

Your density information should be in the official report from your mammogram, so ask your doctor for a copy of this report. Do not rely on the form letter you receive from the mammography center; this will not include your density. If it’s not in the official report, call the radiologist who read your films and ask them. It might take some legwork, but you have a right to know this! If you have “heterogeneously dense” or “extremely dense” breasts, your doctor should send you for an additional screening test each year in addition to a mammogram. If you are at high risk for breast cancer, that test should be an MRI. If you are of average risk, you should be having an ultrasound and a mammogram every year. Don’t rely on a mammogram alone, which will only find half of cancers for you! Your life is too important.


For more information:

Government Mammography Task Force vs. You

When a Mammogram Alone is Not Enough

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  • Diane

    The little voice told me, don’t settle for “you have dense breasts,difficult to read your mammo…need more views…then, see you next year”. It didn’t make sense to me. So, off to Montclair Breast center I went with films in hand. I saw their ads in NJ monthly mag for a couple of years and it caught my eye. I knew I arrived at the right place instantly. Mammo hard to read they said…let’s talk to your insurance and get that MRI you are interested in. I had my army(MBC) ready to fight for me. Well, as it turns out, the MRI detected a DCIS,stage 0 in my left breast. No family history to speak of really. Just had that little voice nudging me along. That was 4 years ago. Lumpectomy and radiation and annual ammo,ultrasound,and MRI. I am an operating room nurse. I know quality and sincere care when I see it. At Montclair, they deliver that everyday. They helped save my life. For that, my family is grateful. I am grateful for their care and education in this field. I am grateful for their ability to have and follow their vision.

    • Stacey

      Thank you so much for this. You were so right to not settle.

  • Rich Grable

    Great article! Very informative. Thank you Dr Vitiello. I have some information you and your readers may find interesting.

    Imaging Diagnostic Systems, Inc (IDSI) has developed a innovative breast imaging device, named Computed Tomography Laser Mammography (CTLM®) that utilizes Diffuse Optical Tomography, state-of-the-art laser technology and proprietary algorithms to create three dimensional cross sectional images of the breast with the following benefits:

    • No x-ray radiation
    • No compression
    • No injected contrast agents
    • Can image dense breast

    Nothing touches the patient, she simply positions herself prone on the scan bed and the laser gantry scans the entire breast in minutes. A comfortable and dignified process free of pain, radiation or injections. The scan can be repeated indefinitely with no side effects. CTLM® visualizes the concentration of hemoglobin both normal and abnormal (usually associated with malignancies). It can assist physicians in their advancements with breast care management and may be used as part of their daily routine in breast imaging.

    CTLM® is not FDA approved but has received the following:

    • CE Marking, CMDCAS (Canada) Canadian License
    • UL listing, ISO 13485 certification
    • China SFDA
    • FDA export certification

    For more information go to