br Conflict of interest br The authors
Conflict of interest
The authors declare no conflict of interest.
Appendix A. Supplementary data
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A breast cancer case-control study of polybrominated diphenyl ether (PBDE) T serum levels among California women
Susan Hurleya,b, , Debbie Goldberga,b, June-Soo Parkc, Myrto Petreasc, Leslie Bernsteind, Hoda Anton-Culvere, Susan L. Neuhausend, David O. Nelsonb , Peggy Reynoldsa,b,f a Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, CA, USA b Cancer Prevention Institute of California, Berkeley, CA, USA c Environmental Chemistry Laboratory, Department of Toxic Substances Control, Berkeley, CA, USA d Department of Population Sciences, Beckman Research Institute of City of Hope, Duarte, CA, USA e Department of Epidemiology, School of Medicine, University of California Irvine, Irvine, CA, USA f Stanford University School of Medicine, Department of Health Research and Policy, Stanford, CA, USA
Handling Editor: Heather Stapleton Keywords:
Breast cancer risk Polybrominated diphenyl ethers Persistent organic pollutants Case-control
Purpose: Polybrominated diphenyl ethers (PBDEs) are among the most persistent and pervasive global en-vironmental contaminants. Their toxic and endocrine-disrupting properties have made them a focus of concern for breast cancer. Our objective was to evaluate the risk of breast cancer associated with serum PBDE levels in a case-control study nested within the California Teachers Study.
Methods: Participants were 902 women with invasive breast cancer (cases) and 936 with no such diagnosis (controls) who provided 10 mL of blood and were interviewed between 2011 and 2015. Blood samples were collected from cases an average of 35 months after diagnosis. PBDEs were measured in serum using automated solid phase extraction and gas chromatography/high PFK-158 mass spectrometry. Statistical analyses were restricted to the three congeners with detection frequencies ≥75%: 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47), 2,2′,4,4′,6-pentabromodiphenyl ether (BDE-100), and 2,2′,4,4′,5,5′-hexabromodiphenyl ether (BDE-153). Unconditional logistic regression was used to estimate multivariable-adjusted odds ratios (ORs) and their 95% confidence intervals (CI) for each BDE congener, adjusting for serum lipids and other potential confounders. Results: The OR for each of the three BDE congeners was close to unity with a CI that included one. Analyses stratified by menopausal status, tumor hormone responsiveness, BMI, and changes in body weight yielded si-milarly null results. Conclusions: Our findings provide no evidence that serum levels of BDE-47, BDE-100 or BDE-153 are associated with breast cancer risk. These results should be interpreted in the context of study limitations which include the reliance on PBDE measurements that may not represent pre-diagnostic, early-life or chronic exposures and a lack of information on genetic polymorphisms and other factors which may affect endogenous estrogen levels.
Breast cancer is the leading cancer among women in the United States, with an estimated 266,120 new cases expected to be diagnosed in 2018 (National Cancer Institute (NCI) Surveillance Epidemiology and End Results (SEER), 2013). Established risk factors account for only a fraction of the cases that occur (Cogliano et al., 2011; Madigan et al., 1995). Increasing rates of breast cancer during the latter half of the last century, coupled with the observation of elevated rates in industrialized and urban areas, has led to speculation that environmental pollutants
may play a role in breast cancer etiology (Brody et al., 2007; Gray et al., 2017; Salehi et al., 2008). Polybrominated diphenyl ethers (PBDEs) are a family of synthetic brominated chemicals consisting of over 200 congeners. Introduced in the 1970s, PBDEs were added as flame re-tardants to a variety of consumer products including polyurethane foam cushioning in furniture and carpet padding, hard plastic casings in appliances and electronics, and in upholstery and other household textiles (Agency for Toxic Substances and Disease Registry (ATSDR), 2015; U.S. Environmental Protection Agency (EPA), 2017). After dec-ades of widespread use, PBDEs have migrated from these products into