The Biology of Breast Cancer Disparities in Hispanics: Current Knowledge, Gaps, and Research Opportunities

Excerpt

Hispanic women have a lower incidence of breast cancer and a lower population-based mortality than non-Hispanic white (NHW) women. However, Hispanics with breast cancer are younger, have more advanced disease at presentation, and are more likely to have aggressive subtypes of breast cancers (triple negative and HER2 positive) than NHW. As a result, Hispanic women with breast cancer have a higher mortality than NHW. Data show that socioeconomic factors (low SES, lack of insurance, lack of access to care) are the most significant contributors to these disparities. The greatest disparities in outcomes and mortality exist among young breast cancer subsets. We hypothesize that low SES factors and associated increased stress and poor dietary habits lead to higher incidence of childhood obesity in Hispanics. Obesity leads to increased production of serum IL-6 and other adipokines, increasing aromatase transcription; this leads to increased serum estrogen and genotoxic estrogen metabolites, contributing to higher incidence of early onset breast cancer with its worse prognosis. Recent data support this hypothesis, showing that obesity in pre-pubertal girls leads to higher serum estradiol concentrations and higher levels of genotoxic estrogen metabolites. Epidemiological data show that prolonged exposure to hormonal contraceptives leads to higher breast cancer risk, supporting the idea that a potential factor in breast carcinogenesis and breast cancer disparities is a continuum of increased exposure to estrogen from early childhood to adulthood. Thus, focusing preventive breast cancer research interventions during childhood and early adulthood in low socioeconomic neighborhoods may significantly ameliorate breast cancer disparities in Hispanics.