Breast cancer risk associated with congeners of polychlorinated biphenyls

Experimental studies show that hormonal and nonhormonal activities of polyc hlorinated biphenyls (PCBs) are structure dependent, suggesting that the br east cancer risk associated with PCBs may vary according to specific PCB co ngeners, In 1994-1997, the authors conducted a case-control study of Connec ticut women to investigate whether breast cancer risk is associated with bo dy burden of PCBs and Varies by PCB congeners. A total of 304 breast cancer cases and 186 controls aged 40-79 years were recruited into the study. Fre sh breast adipose tissue was analyzed for PCBs. The age- and lipid-adjusted geometric mean tissue levels of total PCBs were not significantly differen t (p = 0.46) far the cases (478.6 parts per billion) and controls (494.1 pa rts per billion). The covariate-adjusted odds ratio was 0.7 (95% confidence interval: 0.4, 1.1) for ail study participants when the third tertile was compared with the lowest tertile. No individual congeners or groups of cong eners were associated with a significantly increased risk of breast cancer. Further stratification by type of breast disease; menopausal, parity, and lactation status; and body size also showed no significant association with body levels of PCBs. These results suggest that environmental exposure to PCBs may not substantially affect breast cancer risk.