Risk of breast cancer and adipose tissue concentrations of polychlorinated biphenyls and organochlorine pesticides: a hospital-based case-control study in Chinese women.

Polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT), and dichlorodiphenyldichloroethylene (DDE) are suspected to be associated with breast cancer risk, but the results are controversial. This study was performed to evaluate the associations between adipose tissue PCB, DDT, and DDE concentrations and breast cancer risk. Two hundred and nine pathologically diagnosed breast cancer cases and 165 controls were recruited from three local hospitals in Shantou city, China, from 2014 to 2016. Concentrations of 7 PCB congeners, p,p'-DDT, and p,p'-DDE were measured in adipose tissues obtained from the breast for cases and the breast/abdomen for controls during surgery. Clinicopathologic information and demographic characteristics were collected from medical records. PCBs, p,p'-DDT, and p,p'-DDE concentrations in adipose tissues were compared between cases and controls. Multivariate logistic regression model was used to analyze the risk of breast cancer by PCBs, p,p'-DDT, and p,p'-DDE concentrations in adipose tissues. Breast cancer cases have relatively higher menarche age, higher breastfeeding and postmenopausal proportion than controls. Levels of PCB-52, PCB-101, PCB-118, PCB-138, PCB-153, PCB-180, total PCBs (∑PCBs), and p,p'-DDE were relatively higher in breast cancer cases than controls. Breast cancer risk was increased in the third tertile of PCB-101, PCB-118, PCB-138, PCB-153, PCB-180, ∑PCBs, and p,p'-DDE as compared with the first tertile in both adjusted and unadjusted logistic regression models (odds ratios [ORs] were from 1.58 to 7.88); and increased linearly across categories of PCB-118 and p,p'-DDE in unadjusted model, and PCB-118 and PCB-153 in the adjusted model with trend (all P < 0.01). While breast cancer risk was declined in the second tertile of PCB-28, PCB-52, and PCB-101 in both unadjusted and adjusted models, also second tertile of p,p'-DDT and third tertile of PCB-28 in the adjusted models. This study suggests associations between the exposure of PCBs, p,p'-DDT, and p,p'-DDE and breast cancer risk. Based on adjusted models, PCB-118, PCB-138, PCB-153, PCB-180, ∑PCBs, and p,p'-DDE exposures increase breast cancer risk at current exposure levels, despite existing inconsistent even inverse results in PCB-28, PCB-52, PCB-101, and p,p'-DDT. More epidemiological studies are still needed to verify these findings in different populations.