Breast density is the term used to describe the variation in dense tissue on a mammogram image. Fatty breast tissue appears more radiologically translucent than dense (fibroglandular) breast tissue. Regions of a breast that comprise fatty tissue will appear darker on a mammogram, while regions that comprise dense tissue appear whiter.

Researchers conducted a national cross-sectional survey of 2,311 women ages 40 to 74 in English and Spanish. The survey response rate was 65 percent. Overall, more than half of women who responded (58 percent) had heard of breast density, 49 percent were aware that breast density affects breast cancer detection and 53 percent knew that breast density is associated with cancer risk.