Serum organochlorine pesticides and PCBs and breast cancer risk: results from a prospective analysis (USA)

Objective: To prospectively evaluate relationships of organochlorine pestic ides and polychlorinated biphenyls (PCBs) with breast cancer, we conducted a case-control study nested in a cohort using the Columbia, Missouri Breast Cancer Serum Bank. Methods: Women donated blood in 1977-87, and during up to 9.5 years follow- up, 105 donors who met the inclusion criteria for the current study were di agnosed with breast cancer. For each case, two controls matched on age and date of blood collection were selected. Five DDT [2,2-bis(p-chlorophenyl)-1 ,1,1-trichloroethane] analogs, 13 other organochlorine pesticides, and 27 P CBs were measured in serum. Results: Women in the upper three quartiles of hexachlorobenzene were at tw ice the risk of breast cancer compared to those in the lowest quartile. How ever, there was no evidence for a dose-response relationship, and the assoc iation was limited to women whose blood was collected close to the time of diagnosis. Women with higher serum levels of other organochlorine pesticide s and PCBs showed no increased risk of breast cancer overall, although posi tive associations were suggested for PCB-118 and PCB-138 when brood was col lected close to the time of diagnosis. Conclusions: Results of this study do not support a role for organochlorine pesticides and PCBs in breast cancer etiology.