Breast Density and BMI Should Be Considered Before Additional Breast Cancer Screening, Study Finds

Dense breasts are a risk factor for breast cancer and can make mammograms more difficult to read. As a result, the U.S. Food and Drug Administration recently updated regulations to require facilities that give mammograms to inform patients if they have dense breasts. As part of the update, patients are encouraged to talk to their doctors about their risk and individual situations. However, a new study finds that another factor should also be considered when sending women with dense breasts for supplemental screening.

Researchers from UC San Francisco and UC Davis recently investigated breast density in more than 2.6 million records at 140 radiology facilities across the country. These records came from more than 866,000 women. During their investigation, they found that BMI – which is also linked with breast cancer risk – is an important indicator to take into consideration before recommending additional screening.

Woman in pink shirt doing self-check on breasts

Dr. Karla Kerlikowske, lead author and UCSF professor in the Departments of Medicine and Epidemiology and Biostatistics, explains, “The goal of breast notification laws is to identify women who are at increased risk of breast cancer and might benefit from supplemental imaging.

“But we found that incorporating breast density and BMI would better identify women with high breast density at risk of a missed or advanced cancer rather than using breast density alone.”

Their findings, published in the journal Cancer, Epidemiology, Biomarkers & Prevention, showed that dense breasts were most common in Asian women, at 66%, followed by white women and Hispanic/Latina women at around 45%, and Black women at 37%. When looking at BMI, obesity rates were highest among Black women (58.4%), followed by Hispanic/Latina women (39.3%), white women (30.6%), and Asian women (8.5%).

Woman in green top checks breasts in mirror

The team says these racial and ethnic differences in breast density are clinically important, though they lowered with age, menopausal status, and BMI. As a result of these differences and in an effort to avoid inequitable screening strategies, the researchers say it’s important to consider BMI when they notify patients about dense breasts.

Dr. Michael C. S. Bissell, co-lead author and biostatistician and epidemiologist at UC Davis, says, “Asian women may be notified and receive a recommendation for supplemental imaging too often, while Black women with higher BMI but lower density may not be notified or receive a recommendation for supplemental imaging often enough that they are at higher risk of breast cancer and advanced breast cancer despite routine screening.”

This is important, as breast cancer outcomes differ by race, with Black women facing higher mortality overall, particularly at a younger age.

To read more of the UC San Francisco and Davis study and learn about their breast cancer screening recommendations, click here.

Young woman getting mammogram in clinic
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