Mammogram Results: What is Breast Density and Why Should You Care?
Reviewed and updated March 2026
Actress Amanda Peet recently shared her breast cancer diagnosis, offering an important reminder for women with dense breast tissue. After years of extra monitoring, her care team detected a cancer that a mammogram alone may have missed. We spoke to radiologist Steven Scallon, MD, to learn more about why breast density matters, who is more likely to have it and what steps women can take to protect their health.
What is breast density?
All women have three types of tissue in their breasts: glandular tissue, fibrous tissue and fatty tissue. If a woman has more glandular and fibrous tissue on her mammogram compared with fatty tissue, then she is considered to have dense breasts.
Why is breast density important?
Detecting cancer in dense breast tissue on a mammogram can be more difficult. Dense breast tissue shows up as white (radiopaque) on a mammogram. Since both dense breast tissue and cancer appear white on a mammogram, dense breast tissue can potentially obscure an underlying breast cancer. This is called the “masking effect.”
Having dense breasts is also a risk factor for developing breast cancer. About half of U.S. women over 40 have dense breast tissue. Additional screening tests are often needed to get a better picture of what is going on inside a dense breast.
Who is more likely to have dense breast tissue?
According to the Centers for Disease Control and Prevention (CDC), the density of your breasts can change over time but generally, you’re more likely to have dense breasts if you:
- Are younger.
- Are pregnant or breastfeeding.
- Are taking hormone replacement therapy.
- Have a lower body weight.
Will I be notified if my mammogram determines I have dense breast tissue?
On March 9, 2023, the U.S. Food and Drug Administration announced that mammogram providers must notify women if they have dense breast tissue and recommend additional screenings as needed. In the state of Washington, this has been a mandate since Jan. 1, 2019. If you are a patient at Overlake, our radiologists notify patients about their breast density via MyChart or by letter.
What can women with dense breast tissue do to protect themselves?
Overlake Breast Health Center offers advanced imaging options to better evaluate dense breast tissue. In addition to mammograms, some women may benefit from supplemental screening — such as breast ultrasound or breast magnetic resonance imaging (MRI) — which can detect cancers that may not be visible on a mammogram alone. In Feb. 2026, Overlake introduced automated breast ultrasound technology, a newer screening option designed specifically for women with dense breast tissue.
If you have dense breast tissue or questions about your personal risk, talk with your provider about whether additional screening is right for you. A Washington state law that took effect Jan. 1, 2024, also eliminates out-of-pocket costs for many diagnostic and supplemental breast exams, making these screenings more accessible.
Over a lifetime, about one in eight women will get breast cancer, according to the CDC. Mammograms continue to be the best tool for breast cancer screening and detection. Overlake Breast Health is proud to offer the most advanced imaging options to accurately respond to the challenge of imaging dense breast tissue. To schedule your mammogram, call 425-688-5985 today.
