Risk of female breast cancer associated with serum polychlorinated biphenyls and 1,1-dichloro-2,2 '-bis(p-chlorophenyl)ethylene

This case-control study was designed to investigate the relationship betwee n polychlorinated biphenyls (PCBs) and 1,1-dichloro-2,2'-bis(p-chlorophenyl )ethylene (DDE) and breast cancer risk in Connecticut. Cases were incident breast cancer patients who were either residents of Tolland County or who h ad a breast-related surgery at the Yale-New Haven Hospital in New Haven Cou nty. Controls were randomly selected from Tolland County residents or from patients who had newly diagnosed benign breast diseases or normal tissue at Yale-New Haven Hospital. A total of 475 cases and 502 controls had their s erum samples analyzed for PCBs and DDE in 1995-1997, The age- and lipid-adj usted geometric mean serum level of DDE was comparable between the cases (4 60.1 ppb) and controls (456.2 ppb), The geometric mean serum level of PCBs was also comparable between cases (733.1 ppb) and controls (747.6 ppb), Aft er adjustment for confounding factors, odds ratios of 0.96 (95% confidence interval, 0.67-1.36) for DDE and 0.95 (95% confidence interval, 0.68-1.32) for PCBs were observed when the third tertile was compared with the lowest. Further stratification by parity, lactation, and menopausal and estrogen r eceptor status also showed no significant association with serum levels of DDE or PCBs. The results by PCB congener groups also showed no major increa sed risk associated with any of the congener groups, Our study does not sup port the hypothesis that DDE and PCBs, as encountered through environmental exposure, increase the risk of female breast cancer.