β-Benzene hexachloride in breast adipose tissue and risk of breast carcinoma

Epidemiologic studies have recently related benzene hexachloride (BHC) to breast carcinoma risk. Experimental studies have also shown that β-BHC is weakly estrogenic, hence supporting the alleged association. By directly comparing β-BHC levels in breast adipose tissue from incident breast carcinoma cases and controls, this study examined the hypothesis that exposure to β-BHC increases the risk of breast carcinoma in females. A total of 490 Connecticut women (304 cases and 186 controls) were enrolled in the study during the period 1994–1997. Cases were patients ages 40–79 years with histologically confirmed incident primary breast carcinoma. Controls were patients with histologically confirmed incident benign breast disease. Breast adipose tissue was collected and analyzed for BHC isomers. A linear logistic regression model was used to adjust for potential confounders in estimating the association of exposure with disease. No significant differences in breast adipose tissue levels of β-BHC were observed between the cases and their controls overall, nor by menopausal status or estrogen and progesterone receptor status of the breast carcinoma cases. A nonsignificant reduced risk was observed among all subjects and among pre- and postmenopausal women when the highest quartile was compared with the lowest. Parous women with higher β-BHC levels, regardless of lactation status, had a nonsignificantly reduced breast carcinoma risk, whereas a nonsignificantly increased risk was observed among nulliparous women with higher β-BHC levels, based on very few study subjects. The results of this study do not support the hypothesis that increasing adipose tissue levels of β-BHC are associated with an increased risk of breast carcinoma in females. Cancer 1999;85:2212–8. © 1999 American Cancer Society.