Associations of breast cancer risk factors with breast density in Hispanic women

Although there has been much research on the factors associated with breast density, most studies did not include Hispanic women or relied on semiquantitative methods of assessing density. Using data from the Chicago Breast Health Project, which targeted Hispanic women and assessed density quantitatively using full-field digital mammography, we assessed cross-sectional associations of breast cancer risk factors with percentage of breast density. Between November 2000 and June 2002, 296 Hispanic women recruited from three community health centers in Chicago, Illinois completed a health and lifestyle questionnaire, had their height and weight measured, and underwent screening mammography. The average percentage of total breast area occupied by fibroglandular tissue was computed from each mammographic view. Associations of breast cancer risk factors with percentage of breast density were assessed using multivariate linear regression analyses. Overall, the mean percentage of breast density was 17.6%. In multivariate analysis, older age was associated with lower density (P = 0.03), and density was lower among postmenopausal than premenopausal women (13 5.2%; P = 0.002). Body mass index was significantly inversely related to percentage of breast density (P < 0.00001). Women currently taking hormone replacement therapy had a higher percentage of breast density (beta = 3.3%; P = 0.03). In premenopausal women, cigarette smokers had a marginally higher percentage of density (beta = 6.23%; P = 0.06) compared with nonsmokers, but there was no relationship for postmenopausal women. Other breast cancer risk factors were not associated with density. In summary, breast density was strongly and inversely associated with age, body mass index, and menopausal status, and positively associated with hormone replacement therapy use and cigarette smoking. Additional research focusing on relationships of other, potentially modifiable, factors with the extent of breast density is warranted to better understand the interindividual variability in density among Hispanic women.