Ongoing research to identify environmental risk factors in breast carcinoma.

Environmental exposures, timing and duration of exposure, and one's genetic susceptibility all contribute to breast carcinoma and its progression. The purpose of this article was to identify known and suspected environmental causes of breast carcinoma, identify some environmental risk factors that may represent significant risk factors for certain groups, and describe current studies, supported by the National Institutes of Health/National Institute of Environmental Health Sciences, that clarify how environmental factors contribute to the development of breast carcinoma. Known and suspected environmental risk factors include organochlorine pesticides and other synthetic chemicals, hormonal factors (including exogenous endocrine disrupters), diet, tobacco and alcohol use, radiation, and magnetic fields. In at least 50% of breast carcinoma cases, none of the known risk factors apply. It is likely that an environmental component accounts for much of the unknown 50% of risk. Knowing the environmental factors for breast carcinoma development is an area that should be investigated intensely because it offers our best hope for prevention. Understanding why African-American women have a more aggressive form of breast carcinoma, whether they receive adequate follow-up treatment, and how these factors contribute to increased mortality rates requires further exploration. Data that demonstrate the lower incidence rate of breast carcinoma in Asian women, the relation to low fat diets and diets high in phytoestrogens, and how this might serve as a model for all women should be investigated. Finally, differences in behavioral and cultural attitudes, ethnicity, economic status, and life-style influences among different groups of women require further study to determine how these factors contribute to enhancing or reducing breast carcinoma risk.