Latina women in the US have lower incidence of breast cancer than African American and non-Latina white women, but their survival rate is lower than non-Latina whites. The degree to which these differences are due to genetic vs. non-genetic factors (environmental, reproductive or other) remains unclear. The main goal of this project is to identify common genetic risk variants in Latinas that affect breast cancer subtype-specific risk and progression and address the generalizability of these risk factors across different Latino ethnic groups and environments. In particular, we will use existing data from a genome wide association analysis (GWAS) in a sample of 2,900 US Latinas (1,600 cases and 1,300 controls) to address the following specific aims: (1) identify common genetic risk variants for breast cancer subtypes, and (2) identify common genetic risk variants for breast cancer progression and breast cancer specific survival. We will also (3) evaluate the effect of confirmed or suggestive risk variants identified in Aim 1 and through other published GWAS studies in a sample of breast cancer cases from Argentina, and (4) evaluate if the effect of confirmed or suggestive variants that affect progression and survival identified in Aim 2 and through other published studies have an effect on disease progression in the sample from Argentina. For the first two aims, genome wide genotype, tumor characteristic and survival information is available for samples from the San Francisco Bay Area Breast Cancer Study, the Breast Cancer Family Registry and the Multiethnic Cohort Study. For aims 3 and 4 we will genotype 192 SNPs (previously confirmed or suggestive variants) in 600 Argentine cases from the US-Latin America Cancer Research Network study. This project will be the first GWAS study in Latinas by hormone receptor status and by progression and survival.