Breast Adipose Tissue Concentrations of Polychlorinated Biphenyls and Other Organochlorines and Breast Cancer Risk

Breast Adipose Tissue Concentrations of Polychlorinated Biphenyls and Other Organochlorines and Breast Cancer Risk1

Departments of Community Health and Epidemiology [K. J. A., C. G. W.], Surgery [E. E. S.], and Pathology [S. K. S.], Queen’s University, Kingston, Ontario, K7L 3N6 Canada; Division of Clinical Epidemiology, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 280, D-69120 Heidelberg, Germany [A. B. M.]; Surgical Oncology, Princess Margaret Hospital, Toronto, Ontario, M5G 2M9 Canada [D. R. M.]; Departments of Surgery [L. A. L., E. B. F., G. Y. H., C. H., T. R.] and Pathology [W. M. H.], Women’s College Hospital, Toronto, Ontario, M5S 1B2 Canada; and Le Centre de Toxicologie du Québec, Sainte-Foy, Quebec, G1V 4G2 Canada [J-P. W.]

Abstract

Numerous studies have examined the relationship between organochlorines and breast cancer, but the results are not consistent. In most studies, organochlorines were measured in serum, but levels in breast adipose tissue are higher and represent cumulative internal exposure at the target site for breast cancer. Therefore, a hospital-based case-control study was conducted in Ontario, Canada to evaluate the association between breast cancer risk and breast adipose tissue concentrations of several organochlorines. Women scheduled for excision biopsy of the breast were enrolled and completed a questionnaire. The biopsy tissue of 217 cases and 213 benign controls frequency matched by study site and age in 5-year groups was analyzed for 14 polychlorinated biphenyl (PCB) congeners, total PCBs, and 10 other organochlorines, including p,p′-1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene. Multiple logistic regression was used to assess the magnitude of risk. While adjusting for age, menopausal status, and other factors, odds ratios (ORs) were above 1.0 for almost all organochlorines except five pesticide residues. The ORs were above two in the highest concentration categories of PCB congeners 105 and 118, and the ORs for these PCBs increased linearly across categories (Ps for trend≤ 0.01). Differences by menopausal status are noted especially for PCBs 105 and 118, with risks higher among premenopausal women, and for PCBs 170 and 180, with risks higher among postmenopausal women. Clear associations with breast cancer risk were demonstrated in this study for some PCBs measured in breast adipose tissue.

Footnotes

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↵1 Supported by the Canadian Breast Cancer Research Initiative, with additional support from the Lloyd Carr-Harris Foundation following a pilot study funded by Health Canada and by a Career Scientist Award from the Ontario Ministry of Health (to K. J. A.).
↵2 To whom requests for reprints should be addressed, at Department of Community Health and Epidemiology, Abramsky Hall, Queen’s University, Kingston, Ontario, K7L 3N6 Canada. Phone: 613-533-6000, ext. 74953; Fax: 613-533-6686; E-mail: aronson{at}post.queensu.ca
↵3 The abbreviations used are: DDT, 2,2-bis(p-chlorophenyl)-1,1,1-trichloroethane; DDE, 1,1-dichloro-2,2-bis(p-chlorophenyl)-ethylene; BBD, benign breast disease; BMI, body mass index; CI, confidence interval; GM, geometric mean; HCB, hexachlorobenzene; β-HCH,β -hexachlorocyclohexane; OR, odds ratio; PCB, polychlorinated biphenyl; HRT, hormone replacement therapy.
- Accepted November 1, 1999.
- Received June 1, 1999.
- Revision received September 30, 1999.