To compare mammographic density among premenopausal and early perimenopausal women from four racial/ethnic groups and to examine density and acculturation among Japanese and Chinese women.
The study included 391 white, 60 African American, 171 Japanese, and 179 Chinese participants in the Study of Women's Health Across the Nation, a multisite study of US women transitioning through menopause. Mammograms done when women were premenopausal or early perimenopausal were assessed for area of dense breast tissue and the percent of the breast occupied by dense tissue (percent density). Information on race/ethnicity, acculturation, and other factors was obtained from standardized instruments. Multiple linear regression modeling was used to examine the association between race/ethnicity or acculturation and density measures.
Age-adjusted mean percent density was highest for Chinese (52%) and lowest for African American (34%) women. After additional adjustment for body mass index, menopause status, age at first birth, breast-feeding duration, waist circumference, and smoking, African Americans had the highest mean percent density (51%) and Japanese women had the lowest (39%). In contrast, the area of dense tissue was highest for African Americans and similar for white, Japanese, and Chinese women. Less acculturated Chinese and Japanese women tended to have a larger area of density and a higher percent density.
Neither the age-adjusted nor fully adjusted results for percent density or area of dense tissue reflected current differences in breast cancer incidence rates among similarly aged African American, Japanese, Chinese, and white women. In addition, mammographic density was higher in less acculturated Asian women.
In a multiethnic cohort of premenopausal or early perimenopausal women, observed differences in the percentage of density and area of dense tissue did not reflect current differences in breast cancer incidence rates among similarly aged African American, Japanese, Chinese, and white women. In addition, mammographic density was higher in less acculturated Asian women.
From the 1Division of Research, Kaiser Permanente, Oakland, CA; 2David Geffen School of Medicine at UCLA, Los Angeles, CA; 3University of Pittsburgh, Pittsburgh, Pittsburgh, PA; 4University of California, Davis, CA; and 5MSW Consulting, Bloomfield Hills, MI.
Received November 1, 2006; revised and accepted December 20, 2006.
Funding/support: This ancillary study was supported by National Cancer Institute grant R01 CA89552. Dr. Crandall was supported by National Institute on Aging grant 5K12AG01004 and by grant 8KB-0035 from the California Breast Cancer Research Program. Dr. Modugno was supported by National Cancer Institute grant K07-CA80668. The Study of Women's Health Across the Nation has grant support from the National Institutes of Health, Department of Health and Human Services, through the National Institute on Aging, the National Institute of Nursing Research, and the Office of Research on Women's Health (grants NR004061, AG012505, AG012535, AG012531, AG012539, AG012546, AG012553, AG012554, and AG012495).
Financial disclosure: None reported.
Address correspondence to: Laurel A. Habel, PhD, 2000 Broadway, Oakland, CA 94612. E-mail: Laurel.Habel@kp.org.