Accumulation of environmental estrogens in adipose tissue of breast cancer patients

Abstract

Although the estrogenic properties of numerous chloroorganic pesticides have been widely recognized, population studies do not give clear results indicating the link between the exposure to these compounds and breast cancer development. Because of the weak affinity of these pesticides to estrogen receptors, they probably act by affecting the expression of CYP genes encoding cytochromes P450 engaged in the metabolism of environmental as well as natural estrogens. To examine the possible correlation between environmental estrogen levels in adipose tissue and breast cancer stage, grade, receptor status and onset of the disease, adipose tissue was isolated from 54 breast cancer patients and 23 healthy individuals. Clinical characteristics were obtained from the medical records, while the information concerning exposure to environmental estrogens where obtained from questionnaires. The environmental estrogens were identified and quantified by GC-chromatography. The data was analyzed with the use of Student t-test and Spearman correlation. The levels of most environmental estrogens did not differ between the patients and the controls, except the β -HCH (β -hexachlorocyclohexane) level, which was higher in the patients than in the healthy individuals. Significantly higher levels of DDE (1,1-bis(4-chlorophenyl)-2,2-dichloroethene) and DDT (1,1,1-trichloro-2,2-bis(4-chlorophenol)ethane) (P < 0.05) were observed in the patients with late onset of the disease which was probably due to the time of exposure. Moreover, in the patients exposed to environmental estrogens, significantly higher concentrations of DDD (1,1-bis(4-chlorophenyl)-2,2-dichloroethane) were found (P < 0.05). We also evidenced that estrogen-independent cancer was more frequent in the patients exposed to numerous risk factors in which higher levels of HCB (hexachlorobenzene), γ -HCH (γ -hexachlorocyclohexane), DDD and DDT in adipose tissue were detected. Breast cancer development is probably related to the accumulation of DDT and its derivatives, but the effect appears only in older patients. We postulate that environmental estrogens acting together with other risk factors might influence the progress and exacerbate the prognosis of breast cancer.

Keywords:

• Environmental estrogens
• DDT
• HCH
• HCB
• breast cancer

Acknowledgments

We are grateful to Prof. M. Spaczynski M.D., Ph.D., Head of the Department of Oncological Gynecology, for giving us access to the tissue samples. Invaluable help of W. Zeugner M.Sc. from the Department of Tumor Pathology in taking tissue samples, M. Lacinski M.D., Ph. D. in statistical analysis, and editorial assistance of Bruno Perossa are gratefully acknowledged.

Notes

† t-Student test,

‡Mann–Whitney test, #recounted to original scale.