Abstract Background: Risk of contralateral breast cancer (CBC) is higher in Asian American and Hispanic breast cancer survivors than in non-Hispanic White survivors. We investigated the role of immigration and social factors in CBC. Methods: A pooled cohort (N=4,269) of Asian American and Hispanic women diagnosed with stage I-III first primary breast cancer (FBC) from 1993-2009 was linked with the California Cancer Registry; 131 Asian American and 135 Hispanic women with CBC diagnosed 180 days after FBC diagnosis were identified. We assessed associations of multilevel immigration and social factors (birthplace, language preference, education, socioeconomic status, and other neighborhood characteristics) with risk of CBC overall and by race/ethnicity and age at FBC diagnosis (50, ≥50 years). We also assessed the mediating effect of FBC stage. Results: CBC risk was higher for Hispanic women with Spanish vs. English language preference (hazard ratio=1.43, 95%CI=1.00-2.05). Neighborhood factors (ethnic enclaves, racial/ethnic composition, socioeconomic status) were not associated with CBC risk in either racial/ethnic population. For stage II/III vs. stage I FBC, odds ratios associated with non-U.S. vs. U.S. birthplace (Asian American, Hispanic) and Spanish vs. English language preference (Hispanic) ranged from 1.28 to 1.42. There was no evidence that FBC stage mediated the associations between immigration and social factors and CBC risk. Conclusions: Non-English language preference may be associated with higher CBC risk in Hispanic women, but not in Asian American women. Impact: Hispanic women with Spanish language preference may benefit from interventions addressing challenges in access to care and treatment that adversely impact CBC risk.
John et al. (Fri,) studied this question.