Organochlorine Compounds and Risk of Breast Cancer
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Tongzhang Zheng, M.D., Sc.D.
Yale University, New Haven, Conn. |
Dr. Tongzhang Zheng, of Yale University, New Haven, Conn., and colleagues
conducted a hospital-based case-control study in Connecticut to investigate
risk for breast cancer associated with exposure to organochlorine compounds.
Levels of organochlorine compounds are being measured in breast adipose
(fatty) tissue and blood serum obtained from women who had surgery or
biopsies for breast cancer or benign breast disease.
The organochlorine compounds studied were: hexachlorobenzene (HCB); -benzene
hexachloride (-BHC);
polychlorinated biphenyls (PCBs), a family of chemicals used in coolants
and lubricants in transformers, capacitators, and other electrical equipment;
and DDT and DDE (a metabolite of DDT), which was once widely used in insect
control. Study participants also provided medical and diet histories,
and information on alcohol use, cigarette smoking, and other environmental
exposures.
The study is considered Long Island Breast Cancer Study Project (LIBCSP)-related
because of its potential relevance. As an adjunct to the study, the researchers
conducted a pilot case-control study focusing on Tolland County, Conn.,
an area that is included in the Congressional mandate in order to investigate
possible environmental causes of breast cancer on Long Island. For this
analysis, blood serum and the same types of medical, lifestyle, and risk
factor information were collected as for the Connecticut study. The number
of women diagnosed with breast cancer was too small to permit valid analysis,
however.
The findings from the Connecticut study have been published:
In May 1999, Dr. Zheng and colleagues published separate reports on analyses
of two organochlorine compounds. In the first report, which appeared in
Cancer Epidemiology, Biomarkers & Prevention, the researchers
analyzed risk for breast cancer associated with HCB, and found no increased
risk for the cancer associated with the agent. HCB is formed as a by-product
in the manufacture of chemicals used as solvents, other chlorine-containing
compounds, and pesticides. The study included 304 women who had breast
cancer (cases), and 186 women who had benign breast disease (controls)
who were treated at Yale-New Haven Hospital between 1994 and 1997 and
who were ages 40-79. The researchers did not find a significant difference
in HCB levels in the adipose tissue of cases and controls. Further, they
did not find significant differences in risk for breast cancer when the
data were analyzed according to menopausal status, estrogen or progesterone
receptor status, breast cancer histology (cell type), stage of disease
at diagnosis, type of benign breast disease, or if the women had breast
fed their children.
In the second report, which was published in Cancer, the researchers
analyzed the adipose tissue of the same study population for -BHC,
and found no association between risk for the cancer and this chemical
compound. They did not find significant differences in levels of -BHC
between cases and controls, nor by menopausal status or, among the breast
cancer cases, by estrogen and progesterone receptor status. -BHC
is an isomer (form) of the insecticide benzene hexachloride (BHC), which
is also known as hexachlorocyclohexane.
In a third analysis of the same study population, Dr. Zheng and colleagues
reported on analysis of the relationship between DDE and DDT exposure
and breast cancer risk in the American Journal of Epidemiology.
The researchers did not find differences in levels of DDE and DDT in the
breast adipose tissue of women who had breast cancer and women who did
not have the disease. Thus, these findings do not support an association
between adipose levels of DDE and DDT and breast cancer risk.
Published
Reports
Funding / Timeline
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