Environmental exposure to hexachlorobenzene (HCB) and risk of female breast cancer in Connecticut

Earlier studies have provided inconclusive results relating hexachlorobenze ne (HCB), an organochlorine fungicide, to female breast cancer risk, The cu rrent study, with a total of 304 breast cancer cases and 186 controls recru ited in Connecticut between 1994 and 1997, examined the association by dire ctly comparing breast adipose tissue levels of HCB between incident breast cancer cases and noncancer controls. The cases and controls were patients w ho had breast biopsies or surgery at the Yale-New Haven Hospital (New Haven , CT) and histologically diagnosed either as breast cancer or benign breast disease. Information on major known or suspected risk factors for breast c ancer was obtained through in-person interview by trained interviewers. No significant difference in mean breast adipose tissue levels of HCB was obse rved between breast cancer patients (21.0 ppb) and controls (19.1 ppb) in t his large case-control study. The risk also did not vary significantly by m enopausal status, estrogen or progesterone receptor status of the breast ca ncer cases, breast cancer histology, stage of diagnosis, or type of benign breast disease. Among parous women who reported ever breast feeding, an odd s ratio (OR) of 0.5 [95% confidence interval (CI), 0.2-1.4] was observed wh en the highest quartile was compared with the lowest quartile, However, no association was observed among parous women who reported never breast feedi ng (OR = 0.7; 95% CI, 0.3-1.7 for the fourth quartile), For nulliparous wom en, the adjusted OR was 2.1 (95% CI, 0.5-8.8) for the third tertile when co mpared with the lowest based on few subjects. Therefore, our study does not support a positive association between environmental exposure to HCB and r isk of breast cancer.