Understanding Dense Breasts and Cancer
In 2023, the FDA required all mammography centers to notify women if they have dense breasts and might benefit from additional imaging tests. Now that breast density is part of the annual mammography conversation, many women still have questions about what their density results mean and which screening options are best for monitoring their cancer risk.
“Having dense breast tissue does not mean that you will get breast cancer, but it does mean that you need to be vigilant in getting mammograms once a year, every year, and adding whatever supplemental screening test is appropriate for your level of risk," says Katja Pinker-Domenig, MD, PhD, a member of the Cancer Population Science program at the Herbert Irving Comprehensive Cancer Center (HICCC) and the chief of the division of breast imaging in the department of radiology at Columbia University Vagelos College of Physicians and Surgeons (VP&S).
Starting simple: What do dense breasts mean?
Breasts are made up of a mixture of fatty and fibroglandular tissue. Both fibroglandular tissue and cancers appear white on a mammogram. Having dense breasts means that you have enough dense tissue that could mask an underlying cancer. If you have dense breasts, it means you have more fibroglandular tissue than fatty tissue. About half of women in the U.S. who get a screening mammogram have dense breast tissue.
“Dense breasts as such are not something you can notice, and your doctor may not feel them during a physical exam,” says Dr. Pinker-Domenig. “Breast density is a designation based on what your mammogram images show.”
In cancer screening, density becomes an issue because it appears white on a mammogram, the same color as many cancers, which can hide tumors.
Density can also change over time- women in their 40s may have dense breasts that gradually become less dense with age.
How breast density shapes cancer screening
Dense breast tissue is an independent risk factor that roughly doubles a woman’s risk of breast cancer compared with women who have mostly fatty tissue.
“But density alone isn’t the whole story,” says Dr. Pinker-Domenig. “Someone with extremely dense breasts may have lower overall risk than a woman with a strong family history or genetic mutation. That’s why screening should be tailored to each patient.”
For all women, including those with dense breasts, mammography remains the gold standard for screening. Because dense tissue can make it harder to spot cancer, doctors may also recommend additional imaging, such as ultrasound or MRI, to get a clearer look. A newer option, contrast-enhanced mammography, is also showing promise for supplemental screening in women with dense breasts or at intermediate risk, including those with a history of certain high-risk breast pathologies. These include lobular carcinoma in situ (LCIS), atypical ductal or lobular hyperplasia (ADH/ALH), and a personal history of breast cancer.
“We’re moving toward a layered, risk-adapted approach,” says Dr. Pinker-Domenig. “Not every woman with extremely dense breasts has the same risk and screening needs to reflect that.”
Integrating research and AI for earlier detection
At Columbia, this approach is already taking shape. Researchers are working to bring artificial intelligence (AI) into clinical practice through advanced, image-based tools that can better assess a woman’s individual risk and help doctors decide when additional screening may be needed. They’re also studying how these technologies perform across diverse populations to ensure that every woman benefits equally from these innovations.
“AI is expected to transform screening by acting as a ‘second reader,’” says Dr. Pinker-Domenig.“It can spot subtle patterns that may escape the human eye, improving cancer detection while reducing unnecessary recalls and biopsies.”
In a recent study led by Despina Kontos, PhD, Columbia researchers identified six breast texture patterns linked to higher cancer risk in women. “This shows that we can refine risk even further,” Dr. Pinker-Domenig adds, “leading to more tailored screening schedules and fewer unnecessary tests for women who have dense breast tissue- but are otherwise low risk.”
“Understanding breast density is just the beginning,” says Dr. Pinker-Domenig. “Breast cancer risk varies across racial and ethnic groups, and not everyone has equal access to supplemental screening. At Columbia, we’re leveraging research, AI, and inclusive clinical trials to make sure every woman, regardless of background, has the most accurate, personalized information to guide their screening and care.”
