Estrogen and Breast Cancer Risk: Factors of Exposure

Estrogen is a hormone that is necessary for the normal development and growth of the breasts and organs important for childbearing. It helps control a woman’s menstrual cycles and is essential for reproduction. Estrogen also helps maintain the heart and healthy bones. However, a woman’s risk for breast cancer is associated with lifetime exposure to estrogen. Understanding how estrogen works in the body, knowing about how chemicals in the environment can affect body estrogen levels, and how diet and lifestyle factors affect estrogen exposure over a lifetime, may help women make more informed decisions about their bodies and their environment.

• What is estrogen?
• Is estrogen exposure related to a woman’s risk for breast cancer?
• How can lifestyle factors affect levels of estrogen in the body?
  • Diet
  • Dietary phytoestrogens
  • Body weight
  • Exercise
  • Alcohol
  • Birth control pills
  • Postmenopausal hormone treatment (hormone ‘replacement’ therapy)
• Is there a relationship between breast cancer risk, estrogen, and environmental chemicals?
• What are environmental estrogens?
• Are there other chemicals that affect the levels of and types of estrogen in the body?

Read Estrogen and Breast Cancer Risk: Factors of Exposure, Cornell University Program on Breast Cancer and Environmental Risk Factors, Fact Sheet #10, March 1998, updated July 2002.