The statistics can be grim: Breast cancer is the second most common cancer among women in the United States and constitutes about 30% of all new female cancers each year, according to the American Cancer Society. Overall, a woman in the U.S. has a 13% — or 1 in 8 — chance of developing breast cancer at some point in her life.
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Annual mammography screenings can help detect cancer earlier and save lives. Not all women, however, get the same benefit from this common tool. Some women have dense breasts that make it harder to see cancerous masses on a mammogram.
Here’s what it means and what to do if you’re told you have dense breasts.
[READ: What Is Metastatic Breast Cancer?]
Dense Breasts and Breast Health
As with any health concern, knowledge is power. Getting regular mammograms can help you maintain good breast health, as well as potentially getting early diagnosis and treatment.
What is dense breast tissue?
Dense breast tissue refers to how breast tissue appears on a mammogram, says Dr. Hang T. Dang, a board-certified breast surgical oncologist and director of the breast oncology program at the Center for Cancer Prevention and Treatment at Providence St. Joseph Hospital in Orange County, California.
The breasts are primarily composed of three kinds of tissue:
— Fatty tissue
— Fibrous connective tissue
— Glandular tissue
Dense breasts have a higher amount of glandular and fibrous connective tissue compared to fatty tissue, explains Dr. Jonathan Wehrend, a radiologist with the Santa Clara Valley Medical Center in San Jose, California. X-rays don’t pass through those tissues as easily compared to fatty tissue, which is why they’re called “dense.”
Are dense breasts common?
Yes, about half of all women have dense breasts. Breast density varies from one person to the next, and having dense breast tissue is not abnormal. About 50% of women in the U.S. over age 40 who’ve had a mammogram have dense breasts.
Breast density depends on several factors, including:
— Genetics
— Age
— Weight
“Density may decrease with age, but there is little, if any, change in most women,” says Susan Burnett, a breast oncology nurse navigator with the Leonard Cancer Institute at Mission Hospital in Mission Viejo, California.
What factors influence breast density?
Those more likely to have dense breasts include:
— Younger women
— Those who are pregnant or breastfeeding
— Those with a lower body weight
— People who are using hormone replacement therapy
Understanding Dense Breast Tissue
Dense breast tissue may increase your risk of getting breast cancer, according to the ACS. The reasons why are unclear, though it is a focus of research.
Dense breasts make it more difficult for radiologists to spot cancer on mammograms. Dense breasts and lumps, both benign and cancerous, all appear white, making detecting breast cancer like finding a needle in a haystack. As a result, mammograms can be less accurate in women with dense breasts.
How to identify dense breasts: How do I know if I have dense breasts?
Your radiologist can tell you whether you have dense breasts after reviewing your mammogram images. That information typically appears in the report or letter you’ll receive after you have a mammogram.
Touch and sight aren’t enough to detect breast tissue.
“A woman cannot tell if she has dense breast tissue by self-exam alone,” explains Dr. Tracy Lawrence, senior medical director at L.A. Care Health Plan, the largest publicly operated health plan in the U.S.
Your doctor cannot determine it through those methods either. Instead, your radiologist will examine the images taken during a routine mammogram appointment to make a determination about the density of your breasts.
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Breast Density and Mammogram Reports
Mammogram reports classify breast tissue into one of four density categories, Wehrend explains. These include:
— Almost entirely fatty. About 10% of women have breasts that are composed almost completely of fatty tissue.
— Scattered areas of fibroglandular density. About 40% of women have breast tissue that’s mostly fatty but contains some denser tissue.
— Heterogeneously dense. About 40% of women have breasts that have more dense tissue but still contain some fatty tissue.
— Extremely dense. About 10% of women have very dense breast tissue that includes little fat.
If your report notes that your tissue is “heterogeneously dense” or “extremely dense,” that means you have dense breasts and may need to undergo additional testing for breast cancer.
“A person is considered to have dense breast tissue if they’re in the heterogeneously dense or extremely dense categories,” Wehrend adds.
Inclusion of breast density in mammogram reports
If you’re curious about the density of your breast tissue, talk with your doctor. The radiologist who reads your mammogram can determine that for you.
“In many states, it’s the law to inform patients of their breast density on their mammogram report,” Wehrend says.
In September 2024, reporting on the density of breast tissue became a national requirement, per Food and Drug Administration regulations.
Importance of breast density awareness
Knowing your breast density can help your doctor better screen for potential cancers.
Black women, women from other minority groups and those of Ashkenazi Jewish descent have a higher risk of developing breast cancer than white women, he adds, so it’s even more critical for these patients to stay on top of routine screenings.
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Screenings and Health Care Decisions for Dense Breasts
While traditional mammography is the gold standard for breast cancer screening, women with dense breasts may need some additional tests to help spot cancer early, including:
— Digital breast tomosynthesis (DBT), or 3D mammography
— Breast ultrasound
— Breast MRI
“DBT is a more advanced form of mammography where multiple mammographic images are taken in an arch around the breast and then reconstructed into a 3D image,” Dr. Long Trinh, a radiologist and chief of breast imaging with Santa Clara Valley Medical Center’s department of radiology. “DBT has been shown to decrease the recall rate by 15% to 37% and increase breast cancer detection rate by 1.2 to 1.7 per 1,000.”
Still, some cancers won’t show up even with DBT, so ultrasound and/or a breast MRI may be a more effective option. However, there can be a downside.
“Both MRI and ultrasound show more findings that are not cancer, which can result in added testing,” Burnett says.
Excessive testing can be problematic for a number of reasons, not least of which is the stress and anxiety the patient undergoes when a false positive is detected.
Additional screening tests for dense breast tissue
Your doctor can advise you about which additional screening tests, such as breast ultrasound or breast MRI, might be best for you based on the density of your breasts and your risk of developing breast cancer.
“Not all insurers pay for these tests for a diagnosis of breast density alone, so it is important to check if this is recommended,” Lawrence says. “There are also more advanced techniques, such as contrast enhanced CT or molecular breast imaging using a nuclear medicine camera, but these are not widely available.”
Taking Action: What to Do If You Have Dense Breast Tissue
If you have dense breasts, you should talk with your doctor. It is best to get recommendations from a breast surgeon or breast radiologist about the best way to evaluate your breast tissue and there are calculators that can predict your lifetime risk of breast cancer based on your family history as well as other factors, such as breast density.
“Together you can decide which, if any, additional screening exams are right for you,” Burnett says.
In the meantime, she underscores that “getting your annual mammogram is key starting at age 40 or sooner if you discover a lump or have a strong family history. Early detection is your best protection.”
Questions to consider asking your doctor or nurse
— Do I have dense breasts, and if so, what does that do to my cancer risk levels?
— Should I consider alternative or additional screening measures to detect breast cancer?
— What lifestyle changes can I make to help prevent developing breast cancer if I have dense breasts?
Clinical Trials for Women With Dense Breasts?
There are many studies looking at dense breast tissue and how it impacts cancer risk, as well as which screening tools can be most effective for detecting cancer in people with dense breast tissue. A few examples of current studies include:
— Supplemental Screening for Breast Cancer With Abbreviated Breast Magnetic Resonance for Black Women With Increased Breast Density
— Density MATTERS (Molecular Breast Imaging (MBI) And Tomosynthesis to Eliminate the Reservoir)
— Abbreviated Breast MRI and Digital Tomosynthesis Mammography in Screening Women With Dense Breasts
— Breast Cancer Screening With MRI in Women Aged 50-75 Years With Extremely Dense Breast Tissue: the DENSE Trial
Bottom Line
Having dense breasts is a common phenomenon, but it can increase your risk of developing breast cancer and make it more difficult for your doctor to interpret your mammogram images.
Knowing whether you have dense breasts can help guide your health care choices. Talk with your health care provider for advice tailored to your specific situation.
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What Is Breast Density and Why Does It Matter? originally appeared on usnews.com
Update 09/27/24: This story was published at an earlier date and has been updated with new information.
