Mammography uses X-rays to create images of the breast. These images are called mammograms.
Learn more about mammograms.
Learn about getting a mammogram.
Like other X-ray images, mammograms appear in shades of black, gray and white, depending on the density of the tissue (see images below).
Very dense tissue, like bone, shows up as white on an X-ray. Fat looks dark gray on an X-ray.
Breast cancer and some benign (not cancer) breast conditions are denser than fat and appear a lighter shade of gray or white on a mammogram.
Dense breast tissue can look light gray or white on a mammogram, making the mammogram harder to read.
Since younger women tend to have denser breasts than older women, their mammograms can be harder to read.
After menopause, breast density decreases, making mammograms easier to read.
The mammograms below show a range of breast density. Some breasts are mostly fat (fatty breast) and some breasts are mostly breast tissue (dense breast).
Younger women may have lower breast density after surgery to remove the ovaries (oophorectomy).
For women who use menopausal hormone therapy (MHT), breast density may not decrease until they stop using MHT.
Women with dense breasts (as seen on a mammogram) have a higher risk of breast cancer than women with fatty breasts [16-17].
Learn more about breast density and breast cancer risk.
There's no standard measure of breast density. So, although a measure of breast density may be noted on a mammography report, this measure isn't used to assess risk.
However, by looking at your mammogram or the measure of breast density, your health care provider may conclude you have dense breasts and review options with you.
Some states in the U.S. have laws requiring providers to notify women whose mammograms show they have dense breasts.
Although this information may seem helpful, currently there are no special recommendations or screening guidelines for women with dense breasts.
At this time, it’s not known why women with dense breasts have an increased risk of breast cancer. It’s not clear that lowering breast density would 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 with your provider.
Learn about breast density and breast cancer risk.
At this time, there are no special recommendations or breast cancer screening guidelines for women with dense breasts.
Breast ultrasound and breast MRI (each combined 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.
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. 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 (HHS) to focus research on improving breast cancer screening methods.
Some common benign breast conditions (such as cysts and fibroadenomas) may show up on mammograms as round or oval patches with distinct borders.
Learn more about benign breast conditions.
Calcifications are bits of calcium that can show up on mammograms as small, bright white spots. Most calcifications are benign.
However, certain patterns of calcifications are suspicious and need more testing. Tight clusters or lines of tiny calcifications (microcalcifications) can be a sign of breast cancer.
Calcifications are common. They appear on about half of all mammograms of women ages 50 and older (and on about 1 in 10 mammograms of younger women) .
Calcifications may be related to older age, past injury to the breast or an infection in the breast tissue (called mastitis) .
For women treated for breast cancer in the past, calcifications may also be related to past breast surgery or radiation therapy .
Ductal carcinoma in situ (DCIS) is a non-invasive breast cancer.
On a mammogram, DCIS usually looks like a cluster of microcalcifications. It can be hard to know from a mammogram image whether the cluster is DCIS or invasive breast cancer.
Learn about follow-up after an abnormal mammogram.
Learn more about DCIS.
Invasive breast cancer sometimes appears as a white patch or mass on a mammogram.
The tumor cells don't stay within the clear borders of the mass, but instead invade the nearby breast tissue. The outer edges of these cells look fuzzy or spiky (called spiculated).
Most mammography centers report the results of mammograms using the Breast Imaging Reporting and Data System (BI-RADS®).
BI-RADS® was developed by the American College of Radiology to provide a standard way to describe the findings on mammograms (with categories numbered 0 to 6).
Learn more about the BI-RADS® categories for mammography findings.
Some centers may give you the results of your mammogram at the time of your screening. Otherwise, it may take up to 2 weeks to get your results.
If you don't get your results within 2 weeks, contact your health care provider or the mammography center.
Don’t assume the results were normal because you didn’t get a report. Follow-up to make sure you get your results.
*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.
Facts for Life: Breast Calcifications
Facts for Life: Breast Density
Questions to Ask Your Doctor: Mammography