Environmental Health Perspectives 105, Supplement 3, March 1997

Is There an Association between Exposure to Environmental Estrogens and Breast Cancer?

Stephen H. Safe

Veterinary Physiology and Pharmacology, Texas A&M University, College Station, Texas

Abstract

It was initially reported that levels of polychlorinated biphenyls (PCBs) or p,p´-DDE were elevated in breast cancer patients (serum or tissue) versus controls. These results, coupled with reports that selected environmental estrogens decreased 17ß-estradiol (E2) 2-hydroxylase activity and increased the ratio of 16alpha-hydroxyestrone/2-hydroxyestrone metabolites in MCF-7 human breast cancer cells, have led to the hypothesis that xenoestrogens are a preventable cause of breast cancer. More recent studies and analysis of organochlorine levels in breast cancer patients versus controls show that these contaminants are not elevated in the latter group. Moreover, occupational exposure to relatively high levels of PCBs and DDT/DDE are not associated with an increased incidence of breast cancer. A reexamination of the radiometric E2 2-hydroxylase assay in MCF-7 cells with diverse estrogens, antiestrogens, and carcinogens showed that the mammary carcinogen benzo[a]pyrene induced this response and the antiestrogen ICI 164,384 decreased E2 2-hydroxylase activity. Thus, E2 2-hydroxylase activity and the 16alpha-hydroxyestrone/2-hydroxyestrone metabolite ratio in MCF-7 cells does not predict xenoestrogens or mammary carcinogens. -- Environ Health Perspect 105(Suppl 3):675-678 (1997)

Key words: organochlorines, estrogens, breast cancer, hydroxylase activity

Background

This paper was presented in part at the Workshop on Hormones, Hormone Metabolism, Environment, and Breast Cancer held 28-29 September 1995 in New Orleans, Louisiana. Manuscript received at EHP 18 June 1996; manuscript accepted 11 September 1996.

Address correspondence to Dr. S.H. Safe, Veterinary Physiology and Pharmacology, Texas A&M University, College Station, TX 77843-4466. Telephone: (409) 845-5988. Fax: (409) 862-4929. E-mail: ssafe@cvm.tamu.edu

Abbreviations used: DMBA, dimethylbenz[a]anthracene; E1, estrone; E2, 17ß-estradiol; ER, estrogen receptor; I3C, indole-3-carbinol; PCBs, polychlorinated biphenyls.

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Last Update: April 10, 1997