What Does it Mean to Have Dense Breasts and Why it Matters

In the U.S., almost half of women who are over 40 years old have dense breast tissue. But what does this mean exactly and how can knowing this information help prevent breast cancer?

Breast tissue is made up of milk glands, milk ducts, supportive tissue (dense breast tissue) and fatty tissue (nondense breast tissue). Women with dense breasts have more dense tissue than fatty tissue, and these areas show up as white, nontransparent areas on a mammogram, making cancer detection more difficult.

This year, the FDA updated mammography regulations to require that mammogram facilities notify patients about the density of their breasts, in an effort to further enhance early detection and prevention. Before this update, breast density reporting and state regulations varied and were widely inconsistent. Now, women will receive information about their breast density, how this can affect the accuracy of a mammogram and will be urged to talk to their doctor about their personal risk of breast cancer. These updated regulations will go into effect in early 2024.

It is not clear why some women have more dense tissue than others, but you may be more likely to have dense breasts if you:

• Have low body mass index. Women with less body fat are more likely to have denser breast tissue than those who are overweight or obese.
• Are younger. Some women can have dense tissue at any age, but generally your breast tissue becomes less dense as you age.
• Take hormone therapy for menopause. Women who take hormones to help relieve the signs and symptoms of menopause are more likely to have dense breasts.

Having dense breast tissue is common but knowing that you have it is important because it can mask a potential cancer and go undetected. It is recommended than women with an average risk of breast cancer begin screening at the age of 40 and continue regular screenings each year. Women with dense breasts are considered to have a higher risk of breast cancer and should also be screened annually.

The Centers for Disease Control and Prevention report one in eight women will develop breast cancer in her life. Despite concerns about the detection of cancer in women with dense tissue, mammograms continue to be the best tool for breast cancer screening and detection. Talk to your doctor about your risk factors, and be sure to perform regular breast self-exams, so that you are aware of any changes in your breasts.