The Interaction Between Genetic Ancestry and Breast Cancer Risk Factors among Hispanic women: The Breast Cancer Health Disparities Study
Menée aux Etats-Unis à partir de données portant sur 2 326 femmes hispaniques et 1 854 femmes blanches, cette étude évalue l'association entre l'origine ethnique et le risque de cancer du sein chez des femmes après la ménopause
Background: Hispanic women have lower breast cancer incidence rates than non-Hispanic white (NHW) women. To what extent genetic versus non-genetic factors account for this difference is unknown. Methods: Using logistic regression, we evaluated the interactive influences of established risk factors and ethnicity (self-identified and identified by ancestral informative markers) on breast cancer risk among 2326 Hispanic and 1854 NHW postmenopausal women from the US and Mexico in the Breast Cancer Health Disparities Study. Results: The inverse association between % Native American(NA) ancestry and breast cancer risk was only slightly attenuated after adjusting for known risk factors [lowest versus highest quartile: odds ratio(OR)=1.39, 95% confidence interval(CI)=1.00-1.92 among US Hispanics; OR=1.92 (1.29-2.86) among Mexican women]. The prevalence of several risk factors, as well as the associations with certain factors and breast cancer risk, differed according to genetic admixture. For example, higher BMI was associated with reduced risk among women with lower NA ancestry only [BMI <25 versus >30: OR=0.65 (0.44-0.98) among US Hispanics; OR=0.53 (0.29-0.97) among Mexicans]. The average number of risk factors among cases was inversely related to % NA ancestry. Conclusions: The lower NA ancestry groups were more likely to have the established risk factors, with the exception of BMI. While the majority of factors were associated with risk in the expected directions among all women, BMI had an inverse association among Hispanics with lower NA ancestry. Impact: These data suggest that the established risk factors are less relevant for breast cancer development among women with more NA ancestry.%U http://cebp.aacrjournals.org/content/cebp/early/2016/12/08/1055-9965.EPI-16-0721.full.pdf