In 2017, 55-year-old Leslie Ferris Yerger underwent a routine mammogram and breast ultrasound. Both clearly returned. Two months later, she had an unrelated Texa scan to measure bone density. The technician noticed an abnormality in her pelvis. After further testing, Yerger was diagnosed with stage four breast cancer – an advanced stage of the disease in which the cancer has spread beyond the breasts.
Mammograms and ultrasounds didn't pick up cancer, Yerger says, knowing her dense breast tissue.
“My cancer was not in those pictures,” she says. “I learned that this is not an unusual story.”
According to the National Cancer Institute, approximately 50% of women age 40 or older have dense breasts, which refers to the ratio of fatty tissue to fatty tissue in a person's breast. During a mammogram, dense tissue can make it difficult for technicians to detect cancer.
Although some US states require mammography reports to include information about a patient's breast density and how it may affect their results, there was no federal rule until this year.
In September, the FDA began requiring mammogram reports to include information about breast density and how it may affect patient outcomes. “Dense tissue makes breast cancer more difficult to detect on a mammogram and increases the risk of developing breast cancer,” the disclosure states. “For some people with dense tissue, imaging tests other than mammograms may help detect cancers,” the report says.
The ruling marks an inflection point in the field of breast cancer diagnosis and treatment. But there is still disagreement about what these results mean for screening in the United States or abroad. In the UK, for example, the NHS does not include information on breast density in patients' mammogram reports.
Moving forward, experts say, there needs to be more research and trials, as well as self-advocacy from patients. Here's what you need to know.
What are dense breasts?
Breasts are made up of three types of tissue: fatty breast tissue, fibrous connective tissue, and glandular tissue. These last two, collectively referred to as “fibrous tissue” are denser than adipose tissue. The ratio between fibroglandular tissue and adipose tissue determines whether or not breasts are considered dense; A person with dense breasts has more fibroglandular tissue compared to fat. This determination is not based on a specific ratio, but on the radiologist's subjective assessment, explains Dr. Habib Rahbar, professor of radiology at the University of Washington.
There are four categories of breast density. The first two – purely adipose breast tissue and sparse fibroglandular breast tissue – are considered less dense. The other two – heterogeneous breast tissue (about 40% of women) and very dense breast tissue (about 10% of women) – are considered dense.
Despite its prevalence, “a lot is not understood about breast density and why some people have more dense breasts than others,” says Dr. Angela DeMichele, M.D., professor of medicine at the University of Pennsylvania's Abramson Cancer Center and co-chair of the Breast Cancer Program. Center.
People from certain ethnic groups, such as Asian Americans and black Americans, are more likely to have dense breast tissue, says Dr. Arif Kamal, American's chief patient officer. Cancer Society. It can also run in families.
Additionally, a person's breast density varies from year to year depending on age, hormone levels, menstrual cycle and medication. Although about 50% of women under 40 have dense breasts, that number drops to 25% in women over 60, says Dr. Mariam Lustberg, chief of breast medical oncology at Yale Cancer Center.
How to find out if you have dense breasts?
To find out if you have dense breasts, you should have a mammogram. A radiologist will analyze the results and determine the degree of breast density. As a result of the new FDA ruling, these findings will be included in your mammogram report, along with guidance on whether or not to seek additional testing.
Kamal says breast density is not something that can be self-diagnosed. “When I look at the screen, it says [of a mammogram] Your breasts are dense. It doesn't mean you can feel the difference.
How does breast density affect cancer screening?
The high density of this fibroglandular tissue can make mammograms more difficult to read. Mammograms are X-rays, and X-rays pass through soft tissue like fat more easily, so these areas appear darker on the resulting image. Overly dense tissue appears white and obscures the mammogram area, making it difficult for the radiologist to detect suspicious masses, which also appear white. Lustberg likens it to trying to see through a “blizzard.”
For people with dense breasts, doctors often recommend other imaging in addition to mammograms. This includes a full breast ultrasound, which uses sound waves rather than X-rays to create an image of the breast. “It's a different method, so if something is missing a mass, [the sound wave] It's going to jump a little differently,” Lustberg explains. However, experts disagree about how effective breast ultrasound is; One described them as “of limited value”.
Some doctors may recommend MRI for patients with dense breasts, which is an effective way to detect cancer even in very dense breasts. But MRI can result in false positives. Lustberg says the risk may be justified for those at high risk of breast cancer. MRIs can also help those who are concerned about whether a mammogram is accurate. But for people at average risk, MRIs can cause “unnecessary biopsies” and “increased anxiety.”
Balancing these factors regarding additional testing is “the patient's risk tolerance,” says Kamal.
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“It's very confusing,” DiMichele says. “We don't have a definitive study that shows the right test to do it right [people] Can be with thick breasts [detect] Without cancers leading to more cancers and more biopsies.”
Compounding the problem, Rahber says, is inconsistent access. Such tests are not always covered by insurance, and some patients live in so-called “medical deserts” where advanced or even basic imaging technologies are not available.
Are mammograms still useful?
Does all this mean that mammograms are useless for people with dense breasts? Experts say no.
In addition to detecting dense masses, mammograms can also detect calcifications in the breast. “It's one of the best ways to detect very small cancers,” says DeMichele, especially cancers that don't typically show up densely. Although these calcifications are a little harder to see on mammograms of dense breasts, they are still “very visible,” he says.
Does breast density affect one's cancer risk?
Breast density is a risk factor for cancer, although experts aren't entirely sure why.
People with dense breasts are two to three times more likely to develop breast cancer in their lifetime, says Lustberg. There are many hypotheses as to why this is, although none have been conclusively proven. “Dense breasts appear to have slightly different biology than fatty breast tissue,” says Lustberg.
Experts stress that a person's breast density is a potential risk factor. Breast cancer risk assessment tools, some of which are available online, take into account factors such as a person's age, how old they were when they had their first period, how old they were when they had their first child, and their family history and history of cancer.
“I think it's every woman's right to know her personal risk of breast cancer,” says Lustberg.
How can patients advocate when it comes to breast density?
With no clear, standardized guidelines for breast density screening, much of the responsibility falls on patients to obtain the information they need.
“We should not wait to find out what the scientific community wants to do with a unified voice. There is no time for that,” says Kamal. Instead, she says, patients should emphasize conversations with their doctors to understand their breast cancer risks, and to recommend the care and screening they're comfortable with.
Yerger founded the advocacy group My Density Matters in 2021. Groups like this have been raising awareness about breast density for years. They provide information about breast density, questions to ask health care providers, additional screening options, and advice on how to address potential pushback from doctors and insurance agents.
“What are we asking for? [patients] To do, it's not easy,” says Yerker. “Now, this is what we have to do.”
