Breast density, which is associated with breast cancer risk, was found to be higher in black/African American women than white women when measured using novel quantitative methods, according to research presented at the American Association for Cancer Research’s annual meeting, held on April 18-22, 2015.
“Since breast density is associated with breast cancer risk, a better understanding of racial differences in breast density levels could help us identify women at the highest risk for breast cancer and target prevention strategies to those women,” says Anne Marie McCarthy, PhD, a research fellow at Massachusetts General Hospital in Boston.
Black women in the study had a significantly higher absolute area density of 40.1 cm2 compared with 33.1 cm2 in white women. In addition, black women had a significantly higher volumetric density of 187.2 cm3 compared with 181.6 cm3 in white women.
After adjusting for other factors associated with breast density, including age, body mass index, hormone therapy, and reproductive factors, black women were found to have significantly higher breast density than white women across all measures.
According to McCarthy, breast density refers to the amount of fibroglandular tissue in the breast when observed on a mammogram. Fibroglandular tissue appears as white on the mammogram, making it difficult to visually detect breast cancers. Research has shown that women who have the highest breast density have a four-to-six times greater risk for breast cancer compared with women with lower breast density.
Traditionally, radiologists examine mammograms and assign patients a breast density level; however, this assignment can be subjective, McCarthy says. Instead, in this study, McCarthy and colleagues used fully automated computer algorithms to produce both the conventional two-dimensional breast density measurement and a three-dimensional volumetric estimate of breast density. The study included 1,589 black/African American women and 1,256 white women who underwent screening mammography at the University of Pennsylvania from 2010 to 2011.
“Our findings are using a new, quantitative and, perhaps, more reliable way to measure breast density,” McCarthy says. “Our next step will be to see how quantitative density measures and other imaging biomarkers are associated with cancer risk, cancer subtype, and stage of diagnosis by race.”
This study was funded by the National Institutes of Health. The computer software used for breast density estimation has been made publicly available and free for research purposes by the University of Pennsylvania.