beta-benzene hexachloride in breast adipose tissue and risk of breast carcinoma

BACKGROUND. Epidemiologic studies have recently related benzene hexachlorid e (BHC) to breast carcinoma risk. Experimental studies have also shown that beta-BHC is weakly estrogenic, hence supporting the alleged association. B y directly comparing beta-BHC levels in breast adipose tissue from incident breast carcinoma cases and controls, this study examined the hypothesis th at exposure to beta-BHC increases the risk of breast carcinoma in females. METHODS, A total of 490 Connecticut women (304 cases and 186 controls) were enrolled in the study during the period 1994-1997. Cases were patients age s 40-79 years with histologically confirmed incident primary breast carcino ma. Controls were patients with histologically confirmed incident benign br east disease. Breast adipose tissue was collected and analyzed for BHC isom ers. A linear logistic regression model was used to adjust for potential co nfounders in estimating the association of exposure with disease. RESULTS. No significant differences in breast adipose tissue levels of beta -BHC were observed between the cases and their controls overall, nor by men opausal status or estrogen and progesterone receptor status of the breast c arcinoma cases. A nonsignificant reduced risk was observed among all subjec ts and among pre- and postmenopausal women when the highest quartile was co mpared with the lowest. Parous women with higher beta-BHC levels, regardles s of lactation status, had a nonsignificantly reduced breast carcinoma risk , whereas a nonsignificantly increased risk was observed among nulliparous women with higher beta-BHC levels, based on very few study subjects. CONCLUSIONS. The results of this study do not support the hypothesis that i ncreasing adipose tissue levels of beta-BHC are associated with an increase d risk of breast carcinoma in females. Cancer 1999;85:2212-8, (C) 1999 Amer ican Cancer Society.