Understanding and Preventing Breast Cancer Disparities in Latinas

Relationship of breast cancer subtype, risk factors and ancestory in Hispanic and non-Hispanic white women [CHACO]

Co-Project Leaders:

Peggy Porter, MD, Full Member, Human Biology, FHCRC

Linda Cook, PhD, Full Member, Professor, Department of Epidemiology and Biostatistics – UNM Cancer Center, University of New Mexico

Project 4 within the PUEDO initiative is titled: Collaboration for Hispanic Ancestry and Cancer [CHACO] and aims to better understand the underlying biology of breast cancer in Hispanic women. Disparities in breast cancer survival between racial and ethnic groups of women have some well-documented social and economic causes. It is possible that differences in tumor biology between racial and ethnic groups also contribute to differences in breast cancer outcomes. Breast cancer has considerable biologically variability. Recent gene expression profiling of breast cancer subtypes has deepened our understanding of this very heterogeneous disease and led to a new paradigm for the development of subtype-specific therapies and prevention strategies. However, the gene expression subtyping of breast cancer is based entirely on data generated by studies of non-Hispanic white women. The disparity created by the lack of biological data in minority women will continue to impede the implementation of new approaches to prevention and treatment in women who have diverse genetic backgrounds and possibly diverse risk factors. As new treatments directed at specific subtypes become available it is essential that gene expression data from Hispanic breast cancer cases is also available—both to identify associations specific to Hispanic women and to assess the relevance of data generated in studies of non-Hispanic women.

The development of approaches to reduce breast cancer incidence and mortality in Hispanic women is also complicated by the marked genetic diversity of the Hispanic population. Hispanic women form an admixed population including European, Native American and African ancestry and the prevalence of aggressive estrogen receptor-negative breast cancer in Hispanics falls between those of Europeans (lower rates) and Native Americans and African Americans (both with higher rates). Our hypothesis is that the intermediate prevalence of aggressive breast cancer in Hispanic women is due to the diverse ancestry of the population. If this is the case, information concerning the relationship of ancestry to breast tumor characteristics will be necessary for the development of appropriate and individually targeted treatment for Hispanic women.

Ultimately, the data from this study could help disentangle the genetic and biological contribution to disparities in breast cancer outcomes. Therefore, to better understand the biological subtypes of breast cancer in Hispanic women and the relationship of genetics and environmental influences (risk factors) to the development of specific breast tumor subtypes, we are conducting a study of approximately 600 Hispanic women from New Mexico and the Western Washington area. We aim to determine the relationship between breast tumor subtype and ancestry and to explore the relationship between specific risk factors and breast tumor subtype in Hispanic women.