In JAMA, Lee et al provided a concise, evidence-based summary to help clinicians discuss information regarding breast density and implement shared decision-making with patients following the U.S. Food and Drug Administration (FDA) Mammography Quality Standards Act mandate. Since September 2024, this federal mandate has required that all patients undergoing mammography be informed if their breasts are classified as “dense.”
“This FDA mandate increases the complexity of breast cancer screening for women and their clinicians, many of whom may not be prepared to interpret and act on information about breast density,” the investigators commented.
Detecting Breast Density and Cancer
Radiologists classify breast density into one of four categories based on mammography results: almost entirely fatty; scattered areas of fibroglandular tissue; heterogeneously dense; and extremely dense. Breasts falling into the latter two categories are considered “dense.” Half of all women have been found to have dense breast tissue on mammography.
According to the authors, digital mammography and digital breast tomosynthesis have high accuracy for detecting breast cancer (digital breast tomosynthesis sensitivity: ~ 88%), even in women with dense breasts (77%).
Breast Density and Cancer Risk
Women with dense breasts on routine screening mammography are not automatically considered high-risk; the authors noted that, in the absence of other risk factors, most do not require additional testing. The Tyrer-Cuzick Model, Breast Cancer Risk Assessment Tool, and Breast Cancer Surveillance Consortium risk calculator consider breast density along with other risk factors in estimating the 5-year, 10-year, and/or lifetime risk of developing breast cancer.
Supplemental Screening
After risk assessment, women who are at high risk (> 20% lifetime risk) may be considered for supplemental screening. Screening magnetic resonance imaging (MRI) vs breast ultrasonography is recommended because of its higher sensitivity (> 80% vs 55%). The authors noted that ultrasonography is an option for those with a contraindication to MRI or in settings without access to MRI.
Supplemental screening may lead to earlier detection of breast cancer. However, according to the authors, it may also result in increased anxiety, discomfort, and costs because of unnecessary follow-up tests and interventions.
The investigators concluded: “Approximately half of all women have dense breasts, and those without other breast cancer risk factors should not be considered at high risk for breast cancer. Supplemental screening beyond routine mammography is not warranted for women with dense breasts who are at average risk for breast cancer. The decision to perform supplemental screening with breast MRI or ultrasonography should be based on comprehensive risk assessment (not breast density alone) and should include an individual patient’s values regarding the potential benefits and harms of additional tests and interventions.”
Joann G. Elmore, MD, MPH, of David Geffen School of Medicine at UCLA, Los Angeles, is the corresponding author of the JAMA article.
Disclosure: The authors are funded in part by the National Cancer Institute for breast cancer-related research. For full disclosures of the authors, visit jamanetwork.com.
