Background: Hispanic and non-Hispanic white (NHW) populations within the United States have different breast cancer incidence rates, yet there is limited research on how ethnic differences in the prevalence of established risk factors and their associations with breast cancer contribute to the observed differences.
Methods: Odds ratios and population-attributable risk estimates for breast cancer were determined for Hispanic and NHW women in the population-based, case-control 4-Corners Breast Cancer Study.
Results: When comparing NHW and Hispanic women, the authors observed differences in the prevalence of certain risk factors and in the magnitude and direction of their associations with breast cancer. Hispanic women were more likely to have characteristics associated with lower breast cancer risk, such as younger age at first birth, having more children, shorter height, less hormone use, and less alcohol consumption. Among premenopausal women, ethnic differences in risk were observed with taller height and positive family history, which were not associated with breast cancer among Hispanic women. Among postmenopausal women, associations for certain risk factors were either weaker or were not observed in Hispanics, such as recent estrogen plus progestin hormone therapy use and younger age at menarche. Among NHW women, an estimated 62% to 75% of breast cancers were attributed to the evaluated risk factors compared with 7% to 36% in Hispanic women.
Conclusions: Breast cancer risk factors established in NHW populations had less influence on breast cancer risk in Hispanic women. These findings reflect the need to further evaluate breast cancer risk factors among different ethnic and racial populations.