| Rethinking Breast Cancer Risk and the Environment: The Case for the Precautionary Principle Devra Lee Davis,1,2 Deborah Axelrod,3 Lisa Bailey,4 Mitchell Gaynor,2 and Annie J. Sasco5 1World Resources Institute's Health, Environment, and Development Program, Washington, DC 20006 USA
2Cornell Medical School, Strang Cancer Prevention Center, New York, NY 10021 USA
3Beth Israel Medical Center, New York, NY 10003 USA
4American Cancer Society, Oakland, CA 94612 USA
5Unit of Epidemiology for Cancer Prevention, International Agency for Research on Cancer and Institut National de la Sante et la Recherche Medicale, Lyon, France Abstract
The World Health Organization recently reported that breast cancer has become the most common cancer in women throughout the world. Known risk factors account for less than half of all cases of breast cancer, and inherited germ line mutations occur in at most only 10% of all cases. Cumulative exposure to estradiol and other hormones links many of the established risk factors for breast cancer. This paper reviews epidemiologic and toxicologic evidence on breast cancer risks and presents a comprehensive construct of risk factors intended to focus on the identification of those factors that can be controlled or modified. We attempt to provide a framework for interpreting the etiologic interplay of endogenous metabolic changes and environmental changes in the etiology of breast cancer. The construct we develop distinguishes between those risk factors that are directly causal, such as ionizing radiation and inherited germ cell defects, those vulnerability factors that extend the time period during which the breast undergoes development, and those contributing factors that increase total hormonal stimulation of the breast. Some hormonally active compounds, such as those in soy and broccoli and other phytoestrogen-containing foods, can be protective against breast cancer, while others, such as some environmental contaminants, appear to increase the risk of the disease by increasing levels of harmful hormones. Efforts to explain patterns of breast cancer should distinguish between these different risk factors. Identification of vulnerability and contributing risk factors can foster the development of public policy to reduce the burden of this prevalent cancer. Prudent precautionary principles suggest that reducing exposure to avoidable or modifiable risk factors should receive high priority from the public and private sectors. Key words: breast cancer, environment, hormones, prevention, risk factors, theory. Environ Health Perspect 106:523-529 (1998) . [Online 17 August 1998] http://ehpnet1.niehs.nih.gov/docs/1998/106p523-529davis/ abstract.html Address correspondence to D.L. Davis, 1709 New York Avenue Vulnerability FactorsNW, Washington, DC 20006 USA. We thank J. Shaloff, A.O. Ip, M.J. Pongsiri, and K. Ahmed for assistance in the development of many drafts of this paper. Members of the Breast Cancer Prevention Collaborative Research Group provided important technical assistance, including H.L. Bradlow, L. Jones, M. Wolff, P. Madigan, L. Brinton, S. Zahm, and S. Sieber. This work was supported in part by grants from the following: Wallace Genetics, the Goldman Fund, the Jennifer Altman Fund, the Breast Cancer Fund, the Starfire Fund, and program support from the American Cancer Society and the World Resources Institute. This paper is based on special lectures presented to the Lemelson Center for Invention and Innovation of the Smithsonian Institution, National Museum of American History, and to the Jennifer Altman Fund. Received 15 May 1998 ; accepted 5 August 1998.
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