Abstract PR-5: Risk factor distribution among women of Mexican descent by level of acculturation: Findings from the ELLA Binational Breast Cancer Study
Authors: Zenuk Rachel L. , Carvajal Scott , Nodora Jesse , Wilkinson Anna , Thompson Patricia , Cruz Giovanna , Wertheim Betsy C. , Komenaka Ian , Pond Erika , Brewster Abenaa , Bondy Melissa , Daneri Adrian , Meza Mercedes , Gutiérrez Luis E. , Martinez Maria E. 
Published: December 2010

Purpose of Study: Studies have shown that breast cancer (BC) risk is higher in U.S.-born Hispanics than foreign-born Hispanics and is modified by age at migration, duration of residence in the U.S., and level of acculturation. Furthermore, epidemiological data support the notion of distinct reproductive factor associations for specific BC tumor subtypes. The aim of this study is to assess the association between established BC risk factors and level of acculturation and country of residence among Mexican American (MA) and Mexican BC cases.

Experimental Procedures: This case-only study examined the risk factor profile in 606 Mexican and 488 MA (20% US-born and 80% foreign-born) women, with a confirmed diagnosis of invasive BC, who were recruited into the ELLA Binational Breast Cancer Study between March 1,2007, and May 31,2010. Participants completed an interviewer-administered risk factor questionnaire, consented to a medical record review, and provided tissue and saliva or blood specimens. An eight-item language-based Bidimensional Acculturation Scale (BAS) was used to classify MA women as English-dominant (n=88), bilingual (n=221), or Spanish-dominant (n=179). The BAS is highly correlated with nativity and time in the US, however language use/exposure was focal for this study since it is the single strongest predictor of acculturation. Chi-square tests, ANOVA, and regression models to test for trend were used to assess variation in the risk factor profile by level of acculturation.

Summary of Results: Age at diagnosis was generally low; the lowest was among MA-bilingual women (48.9 = 12.0 years) and highest among Mexican women (53.7 = 12.7 years). Considering a gradient of increasing acculturation from Mexican (lowest) to MA-English dominant (highest) women, there were clear trends for decreasing rates of breastfeeding (80.2 to 35.2%; p-trend&lt;0.0001); earlier age at menarche (13.0 = 1.5 to 12.2 = 1.5 years; p-trend&lt;0.0001), and lower parity (3.9 = 2.5 to 2.6 = 1.2 live births; p-trend&lt;0.0001). However, for some factors, the data show a dichotomy between Mexican and MA-Spanish dominant women versus MA-bilingual and MA-English dominant women; these include oral contraceptive use (51.7% and 47.2% versus 66.1 % and 62.1 %, respectively); age at natural menopause (48.1 and 48.5 vs. 49.2 and 49.1 years, respectively); and hormone replacement therapy use (11.0% and 9.6% vs. 20.0% and 17.2%, respectively). No clear trends or patterns were evident for recent body mass index (BMI), physical activity, or alcohol consumption. MA-Spanish dominant women had the highest BMI (30.2 = 7.1 kg/m2), MA-English dominant women had the lowest levels of physical activity (650.2 = 1265.1 kcal/day), and MA-bilingual women had the highest proportion of alcohol intake (13.8% consumed ≥1 drink/day).

Conclusion: Our results show that heterogeneity in BC risk factor patterns by level of acculturation is present. Given the recent data supporting distinct correlations between specific risk factors and BC subtypes, it will be essential to consider level of acculturation and country of residence when assessing the prevalence of these subtypes. The trends observed in risk factor profiles by level of acculturation in the ELLA Study could provide important explanations for differences in disease patterns between groups.

Citation Information: Cancer Epidemiol Biomarkers Prev 2010;19(10 Suppl):PR-5.