Beginning this week, women in America who get mammograms will not only be told whether their results are normal or abnormal, they’ll also be given information about their breast density under a new rule from the Food and Drug Administration.
While the concept of breast density may be unknown to some women, it’s an important factor in breast cancer screenings that can affect the result of a mammogram. Here’s what you need to know for your next checkup.
What is Breast Density?
Women’s breasts are made up of three types of tissue: fibrous tissue, glandular tissue, and fatty tissue. According to the Centers for Disease Control and Prevention, or CDC, all these tissues have a role to play in breasts.
The fibrous tissue, for instance, helps keep the breasts in place. The glandular tissue is the part of the breasts in charge of milk production and includes lobes (which make milk) and ducts (the tubes that transport it to the nipples). Lastly, the fatty tissue fills in the space between the fibrous tissue, lobes, and ducts, giving the breasts their shape.
Breast density refers to the amount of fibrous and glandular tissue in a women’s breasts compared to the amount of fatty tissue, as seen on a mammogram. Some women have more fatty tissue in their breasts, while others have more fibrous and glandular tissue.
Why Does Having Dense Breasts Matter in a Cancer Screening?
First of all, having dense breasts is a risk factor for breast cancer. As explained by the National Cancer Institute (NCI), women with dense breasts are more likely to develop cancer than women with fatty breasts. Yet, the reason health officials are focusing on dense breasts in cancer screenings isn’t because of the risk factor associated with them, but rather because of how they look on mammograms.
Fibrous and glandular tissue, which are present in larger amounts in dense breasts, appear white on a mammogram, while fatty tissue appears dark. Importantly, possible cancer tumors also appear white. As such, it can be harder to identify a small tumor in dense breasts on a mammogram, and it may be missed.
This comparison image from the CDC shows a non-dense breast (left) and a dense breast (right). Image: CDC
Under the new FDA rule, facilities are required to inform you whether you have dense breasts and recommend you speak to your healthcare provider about next steps.
What Does It Mean to Have “Dense Breasts”?
It’s not possible to tell whether a woman has dense breasts by performing a self-exam or when she’s examined by a doctor. The NCI states that the only way to find out if a woman has dense breasts is through a mammogram.
There are four categories of breast density: entirely fatty breast tissue, scattered fibroglandular breast tissue, heterogeneously dense breast tissue, and extremely dense breast tissue. You can see how they look on a mammogram below.
Image: National Cancer Institute and DenseBreast-info.org
Women with heterogeneously dense breast tissue and extremely dense breast tissue are considered to have "dense" breasts. This means that their breasts either contain a large amount or are almost entirely made up of dense glandular and fibrous tissue. About 50% of women have dense breasts, the CDC states.
It should be noted that dense breasts are common and don’t indicate anything abnormal. Many factors can cause women to have dense breasts, although genetics is the most common. However, women undergoing hormonal menopausal therapy and with a low body mass index (BMI) may also have dense breasts. Women who are younger, pregnant, or breastfeeding are more likely to have them, too.
Will I Have to Get More Tests if I Have Dense Breasts?
That depends on your medical provider. While having dense breasts is a risk factor for developing breast cancer, it’s not the only one. Your doctor will make a recommendation based on other factors, including your age and your family’s history of cancer.
Additional tests can include a breast ultrasound and a breast MRI. However, as noted by CNN, these additional tests often require out-of-pocket costs.
Overall, though, the new FDA rule is another tool for cancer prevention. In a news release, DenseBreast-info, a nonprofit that provides educational resources on breast density, pointed out that some women would be learning that they have dense breasts for the first time.
“To benefit from appropriate screening, women must know their breast density and other risk factors," Dr. Wendie Berg, the chief scientific advisor at DenseBreast-info and radiology professor, said in a statement. "This notification standard is essential to giving women and their health providers the information needed to discuss optimal screening.”
Image | CDC (Modified), National Cancer Institute and DenseBreast-info.org
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