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Janet Gray, Ph.D.
Janet Gray, Ph.D.

As author of our 2008 and 2010 State of the Evidence reports, Dr. Gray drives the science behind all our work.

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The Biology of Breast Cancer

To understand how to reduce breast cancer risk, we first need to look at the biology of breast development, and of how that development can be disrupted. Though scientists still have unanswered questions related to breast cancer causation, we do understand a great deal about the stages of breast development, the impact of endocrine-disrupting compounds and carcinogens, and the interplay between genetics and the environment. This section examines the development of the breast from prenatal stages through menopause, provides an overview of the endocrine system, and outlines the varying breast cancer subtypes.

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    Breast Cancer Subtypes

    There are multiple subtypes of breast cancer that occur at different rates in different groups and have varied long-term survival rates.

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    The Endocrine System

    The endocrine system, which consists of hormone-secreting glands, is responsible for breast development.

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    Endocrine-disrupting Compounds

    Chemicals in everyday products can mimick natural hormones and affect the body's development.

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    Genetic, Epigenetic and Tissue Organizational Effects

    While a variety of gene mutations may influence cancer risk, environmental factors may influence whether those mutations express themselves as cancer or not.

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    The Human Breast

    Breast development occurs at four primary stages that are guided by the body's own hormones, but can be altered by exposure to synthetic chemicals that disrupt the way hormones are made and regulated.

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  • Breast Cancer Statistics

    Today a U.S. woman’s lifetime risk of breast cancer is 1 in 8.

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