Your mammogram found you have dense breasts. What to know now.

An estimated half of all women have dense breasts, but doctors don’t have clear recommendations on what to do.
Stockbridge resident Linda Hensel was diagnosed with breast cancer in 2015. At the time, she was certain she felt a lump in her breast though it could not be seen on a mammogram.  She pushed for more screening which detected cancer at a very early stage. Now she wants women to “listen to that small little voice in your head.” (Chris Hamilton/American Cancer Society)

Credit: Chris Hamilton

Credit: Chris Hamilton

Stockbridge resident Linda Hensel was diagnosed with breast cancer in 2015. At the time, she was certain she felt a lump in her breast though it could not be seen on a mammogram. She pushed for more screening which detected cancer at a very early stage. Now she wants women to “listen to that small little voice in your head.” (Chris Hamilton/American Cancer Society)

When Margie Singleton felt a lump in her left breast in the summer of 2017, she didn’t panic.

Her routine mammograms, including one six months earlier, had always come back normal.

What the 44-year-old Savannah woman didn’t know is that she has dense breast tissue, which can make it far more difficult to detect cancerous tumors. So she was stunned when she was diagnosed with an aggressive form of breast cancer that had already spread to her lymph nodes.

More than one-third of breast cancers are missed by mammography in women with dense breasts, according to estimates by George Washington University Hospital.

And that presents a huge challenge. Roughly half of women over 40 have dense breast tissue, and many don’t know it, just as Singleton didn’t know it.

“My whole world turned upside down,” said Singleton, who underwent chemotherapy, radiation and surgery. She continues to take a daily chemotherapy pill.

“I remember thinking: my daughter, my niece, my family, my friends, other women are not going to get cancer based on something so simple.”

Singleton turned her pain, anger, and frustration into purpose and change.

She became the driving force behind a Georgia bill called “Margie’s Law,” which requires health care facilities notify patients if their mammogram shows dense breast tissue and to include an explanation of what it means for their health.

The state law, which took effect in 2019, also recommends women with dense breast tissue talk to their doctor about whether they need additional screening beyond standard mammograms.

Margie’s Law was followed by a federal requirement issued earlier this year by the U.S. Food and Drug Administration setting a national standard for notifying women about having dense breasts. Facilities have until September 2024 to comply with the federal requirement.

Many women only recently began receiving mammogram results letters that inform them they have dense breasts. But it’s still unclear how women should use that information to protect their health.

Many women recently began receiving mammogram results letters that inform them they have dense breasts. But it’s still unclear how women should use that information to protect their health. (Contributed)

Credit: Contributed

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Credit: Contributed

The current lack of consensus and guidance from doctors and medical groups concerning dense breasts can make it challenging to know what steps to take and whether extra screenings will be covered by insurance.

“Unfortunately, we still have a long way to go as far as educating and putting this information out there to help women better protect themselves,” said Singleton, who founded Margie’s Army Foundation, a nonprofit organization dedicated to raising awareness about the significance of women knowing their breast density.

Higher risk, but few guidelines

Density isn’t related to breast size or firmness, according to Bob Smith, a cancer epidemiologist and senior vice president of Early Cancer Detection Science for the American Cancer Society. It’s a measure of how much fibrous and glandular tissue is in the breasts compared with the amount of fatty tissue, as viewed on a mammogram. Breasts are considered dense if they are composed of more glandular and connective tissue than fat.

The difficulty created by density is that on mammogram X-ray images, cancers show up as white spots or masses, blending in with the dense tissue, which also appears white.

The state and federal rules essentially set a minimum amount of information mammogram providers will be required to tell women: If their breasts are dense or not. But doctors say the degree of density matters too.

Radiologists classify breast density into four categories: A, B, C, and D. These range from extremely fatty to extremely dense, with various combinations in between. Women in categories C and D are considered to have dense breasts under the FDA guidelines. While the degree of density is not required to be included in mammogram results, women should ask health providers for that information.

Doctors say dense breast tissue doesn’t pose an immediate threat to health, but it does increase breast cancer risk, even apart from the difficulty of reading mammograms. It’s unclear why, but women with extremely dense breasts have a risk of breast cancer four to five times higher than women with the lowest densities, according to a study published in the Journal of the National Cancer Institute.

Credit: American Cancer Society

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Credit: American Cancer Society

Dr. Mary Newell, a breast imaging specialist and a physician and researcher at Winship Cancer Institute of Emory University, said for women with dense breasts whose doctors recommend extra screenings, there are several options: ultrasound, MRI, and 3D mammography.

For women who learn their breasts are dense, Newell recommends seeking out 3D mammograms for their annual exams as a first step, and then consulting with their doctor about what else might be needed.

Smith said women with dense breast tissue should also consider going to a specialized health care facility with advanced technologies that can provide quicker and more accurate results. Studies have shown that radiologists who only read breast images detect more cancers and more early-stage cancers.

Medical associations have issued statements on dense breasts but so far have not issued clear advice on what doctors and women should do.

  • The FDA doesn’t specifically recommend additional screening, but the guidelines advise physicians and patients to consider breast density alongside other cancer risk factors when deciding if more imaging is necessary.
  • The U.S. Preventive Services Task Force said women with dense breast tissue, “deserve to know whether and how additional screening might help them stay healthy. Unfortunately, there is not yet enough evidence for the Task Force to recommend for or against additional screening with breast ultrasound or MRI.”
  • The American College of Gynecology and Obstetrics in March released its updated guidance for healthcare practitioners saying women with dense breasts but no additional risk factors for cancer may not need additional screenings, but that more research is needed.

The lack of guidelines means whether a woman with dense breast tissue gets additional screening and whether her insurance will pay often comes down to whether a woman has other risk factors such as a family history of breast cancer and whether her doctor writes a medical order for more tests. Without it, women who push for additional screenings may have to pay out of pocket.

In 2019, Liane Willard of Richmond Hill went for her annual mammogram and received a letter that the results were normal. “See you in a year, Mrs. Willard,” the letter read. But Willard, 54, who has dense breast tissue, demanded an ultrasound. Willard is a registered nurse, but she said she never realized her own dense breasts put her at a higher risk of cancer until her close friend Singleton’s diagnosis.

Willard’s ultrasound picked up a 1 centimeter tumor deep in the breast tissue that turned out to be an aggressive type of cancer. Her mammogram report noted she had “extremely” dense breasts but made no mention of the consideration of additional screenings. Had she not insisted on additional screening, the cancer may not have been found until it had metastasized, she said.

Beyond mammograms

Credit: Contributed

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Credit: Contributed

The new notification requirements for dense breast tissue are a reminder of the shortcomings of basic mammograms. Regardless of breast density, mammograms miss about 1 in every 8 breast cancers, according to the American Cancer Society. That rate is higher for women with dense tissue.

Breast cancer is the second leading cause of cancer death in women in the U.S., expected to kill 43,700 women this year. Only lung cancer kills more women. About 297,790 new cases of invasive breast cancer will be diagnosed in women this year, according to The American Cancer Society.

Doctors still recommend women with dense breasts get mammography as an important first step in screening. Some cancers and precancerous changes will show on a mammogram better than an ultrasound or MRI. One example is calcifications, which are often benign but can sometimes be an early sign of cancer.

An ultrasound is best to investigate masses in the breast, to see if they’re fluid-filled or solid, which can help determine if it’s suspicious or not. An MRI is highly sensitive and can detect changes in the breast tissue that can’t be picked up with a mammogram or an ultrasound.

There’s a relatively new technique that is also being used — contrast-enhanced digital mammography. The procedure uses a low dose of X-rays and contrast dye injected into a vein to make it easier to find new blood vessels around a growing cancer.

An MRI is more sensitive than a mammogram, however a breast MRI, which usually requires the use of contrast dye, may not always be able to distinguish a cancer from a noncancerous growth. This can lead to a false-positives and unnecessary biopsies. They might also detect very early-stage tumors that might never become life-threatening.

“Women should be aware MRI is excellent at detecting cancers but we sometimes find additional benign things as well,” according to Newell of Emory.

Just one piece of the risk

Breast density is one piece of the complex puzzle of breast health.

Lori Plummer is a nurse practitioner with Piedmont Hospital’s recently opened Helen S. Carlos High-Risk Breast Center, which focuses on education and counseling for women at high risk of cancer. She meets with women to do a full breast cancer risk assessment to come up with the percentage likelihood they will develop cancer.

Credit: Contributed

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Credit: Contributed

For women who only have dense breast tissue and no other risk factors, they may fall into a “moderate” risk category. Plummer says other factors linked to an increased risk of breast cancer include a family history of breast cancer, inherited genes that increase cancer risk, beginning your period before 12, never having been pregnant, and the use of hormone replacement therapy. Obesity also increases the risk of cancer.

Besides discussing supplemental screening options, Plummer talks to women about lifestyle modifications to lower their risk — eating healthy, maintaining a healthy weight, exercising, and limiting alcohol.

“I think giving women more information and more education about their health empowers them to make changes and take control of their health and improves outcomes,” she said.

Meanwhile, Singleton’s fight for women’s health continues. She advocates for more clear guidance on additional screening. She wants doctors to have more meaningful conversations with their patients about dense breast tissue. She is pushing for more legislation that would ensure all health insurance plans cover breast cancer screening for women with dense breasts or who otherwise are at a higher risk for breast cancer.

Stockbridge resident Linda Hensel encourages women to “listen to that small little voice in your head.”

“Giving women more information and more education about their health empowers them to make changes and take control of their health and improves outcomes."

- Lori Plummer, a nurse practitioner with Piedmont Hospital’s Helen S. Carlos High-Risk Breast Center

Hensel was diagnosed with breast cancer in 2015. She was 45 at the time, and was certain she felt a lump in her breast though it could not be seen on a mammogram. She asked for more screening and even though nothing was seen on an ultrasound, Hensel didn’t let it go. It felt like a tiny marble. She pushed for more tests and an MRI discovered a tumor, classified as a “stage 0″ — that’s when abnormal cells in the breast have some cancer characteristics, but the cells have not yet spread into other tissues or organs.

“Don’t try to talk yourself out of it because the test and doctor say you’re fine. I couldn’t shake it – I knew what I felt and it wasn’t there before,” said Hensel, who had a lumpectomy and was declared cancer-free eight years ago.

“The doctors are there to support us and help us but we have to help ourselves. I am thankful I listened to that small voice inside that said, ‘Pursue this.’ ... I am so glad I did because I don’t even want to think about what would have happened if I hadn’t gone back until a year later.”

Breast Cancer Screening Methods


Mammograms are low-dose x-rays that most women rely on for their annual breast exams. But dense breasts can make a mammogram more difficult to interpret. That’s because dense breast tissue looks white on a mammogram. Breast masses and cancers can also look white. Standard digital mammography captures two X-ray images of the breast, one from the top and one from the side. These are flat, 2-dimensional images, which means overlapping tissue can hide abnormalities that could be signs of cancer.

3D mammography or digital breast tomosynthesis (DBT): With 3D mammography, the imaging system moves in an arc over the breast, taking multiple X-ray images from various angles.

Contrast-enhanced spectral mammography (CESM). This is a relatively new technique in which a contrast dye is injected into a vein before two sets of X-ray mammograms are taken. The dye can highlight any abnormal areas in the breasts. It allows a better look at areas that appear abnormal on a standard mammogram or to help assess the extent of a tumor in women just diagnosed with breast cancer.

Breast Ultrasound

Breast ultrasound uses sound waves and their echoes to make computer pictures of the inside of the breast. It can show the difference between fluid-filled cysts, which are very unlikely to be cancer, and solid masses, which are more likely to be cancerous.

Breast MRI

Magnetic resonance imaging (MRI) is a technology that excels at examining any soft body tissue. Using strong magnets, the scanner takes images that can appear as “slices” of the body.

A breast MRI requires a contrast dye injected a vein to make any abnormal areas in your breasts easier to see. Although MRI can find some cancers not seen on other screening tests, it’s also more likely to find things that turn out not to be cancer — a false positive.

A new “abbreviated MRI,” also known as a mini-MRI, takes fewer images, is faster and costs significantly less than a standard MRI.

Self-screening: Know your breasts. Any new lump or changes to your breast — shape, feel, color — should not be ignored even if recent screenings came back normal.

One new digital tool designed by scientists that can help health professionals predict the risk of breast cancer for women with dense breast tissue over the next five years as well as over a lifetime is the Breast Cancer Surveillance Consortium Risk Calculator. This tool takes into account breast density as well as other factors including age, race, and family history.

SOURCE: American Cancer Society, The Breast Cancer Surveillance Consortium