This JAMA Internal Medicine Patient Page describes dense breasts and whether they might lead to higher risk for breast cancer.
Importance: Among all US women, breast cancer is the second most common cancer and the second most common cause of cancer death. In 2023, an estimated 43 170 women died of breast cancer. Non-Hispanic White women have the highest incidence of breast cancer and non-Hispanic Black women have the highest mortality rate.
Objective: The USPSTF commissioned a systematic review to evaluate the comparative effectiveness of different mammography-based breast cancer screening strategies by age to start and stop screening, screening interval, modality, use of supplemental imaging, or personalization of screening for breast cancer on the incidence of and progression to advanced breast cancer, breast cancer morbidity, and breast cancer-specific or all-cause mortality, and collaborative modeling studies to complement the evidence from the review.
Population: Cisgender women and all other persons assigned female at birth aged 40 years or older at average risk of breast cancer.
Evidence assessment: The USPSTF concludes with moderate certainty that biennial screening mammography in women aged 40 to 74 years has a moderate net benefit. The USPSTF concludes that the evidence is insufficient to determine the balance of benefits and harms of screening mammography in women 75 years or older and the balance of benefits and harms of supplemental screening for breast cancer with breast ultrasound or magnetic resonance imaging (MRI), regardless of breast density.
Recommendation: The USPSTF recommends biennial screening mammography for women aged 40 to 74 years. (B recommendation) The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of screening mammography in women 75 years or older. (I statement) The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of supplemental screening for breast cancer using breast ultrasonography or MRI in women identified to have dense breasts on an otherwise negative screening mammogram. (I statement).
Breast density, a radiologic term that describes the proportion of parenchymal relative to fatty tissue in mammograms, is a strong and prevalent risk factor. With increasing breast density, the risk of having a breast cancer masked or hidden on mammography increases, as does future breast cancer risk.1 Almost 50% of US women aged 40 to 74 years have dense breasts (an estimated 27.6 million women). The widespread incorporation of breast density information into screening mammography reports in 36 US states and suggestion to consider supplemental imaging has resulted in women raising questions about breast density and supplemental imaging with their clinicians.2 Thus, clinicians need to be knowledgeable of the clinical significance of breast density and how it may be useful when combined with breast cancer risk to inform screening discussions.
