Childhood body size and midlife mammographic breast density in foreign-born and U.S.-born women in New York City

Abstract Purpose We investigated whether childhood body size is associated with midlife mammographic density, a strong risk factor for breast cancer. Methods We collected interview data, including body size at age 10 years using a pictogram, and measured height and weight from 518 women, recruited at the time of screening mammography in New York City (ages 40–64 years, 71% Hispanic, 68% foreign-born). We used linear regression models to examine childhood body size in relation to percent density and areas of dense and nondense tissue, measured using a computer-assisted method from digital mammograms. Results In models that adjusted for race/ethnicity, and age and body mass index at mammogram, the heaviest relative to leanest childhood body size was associated with 5.94% lower percent density (95% confidence interval [CI]: −9.20, −2.29), 7.69 cm 2 smaller dense area (95% CI: −13.94, −0.63), and 26.17 cm 2 larger nondense area (95% CI: 9.42, 43.58). In stratified analysis by menopausal status and nativity, the observed associations were stronger for postmenopausal and U.S.-born women although these differences did not reach statistical significance. Conclusions Heavy childhood body size is associated with lower mammographic density, consistent with its associations with breast cancer risk. Suggestive findings by nativity require confirmation in larger samples.