270248 Exposure to polychlorinated biphenyl (PCB) congeners during pregnancy and subsequent risk of breast cancer before age 50

Tuesday, October 30, 2012

Barbara A. Cohn, PhD , Director, Child Health and Development Studies, Public Health Institute, Berkeley, CA
Mary Beth Terry, PhD , Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, NY
Marj Plumb, DrPH , Plumbline Coaching and Consulting, Inc., Berkeley, CA
Piera M. Cirillo, MPH , Child Health and Development Services, Public Health Institute, Berkeley, CA
Discrete windows of susceptibility to toxicants have been identified for the breast, including in utero, puberty, pregnancy and postpartum. We tested the hypothesis that exposure to polychlorinated biphenyls (PCBs) during pregnancy is associated with increased risk of breast cancer diagnosed before age 50 in a nested case-control study in the Child Health and Development Studies pregnancy cohort (N=129 cases matched to controls on birthyear). We analyzed archived early postpartum serum samples collected an average of 17 years before diagnosis (mean diagnosis age=43 years) for 16 PCB congeners. We used conditional logistic regression to adjust for lipids, race, year, lactation and body mass. The mixture of congeners was variable and we observed strong breast cancer associations with three main congeners. PCB 167 was associated with a lower risk (Odds Ratio (OR), 75th vs. 25th percentile=0.2, 95% confidence interval (95%CI)=0.1, 0.8) as was PCB 187 (OR, 75th vs. 25th percentile=0.4, 95% CI= 0.1, 1.1). In contrast, PCB 203 was associated with a 6-fold increased risk (OR, 75th vs. 25th percentile=6.3, 95%CI=1.9, 21.7). The net effect of PCB exposure was nearly a tripling of breast cancer risk (OR, 75th vs. 25th percentile=2.8 95%CI=1.1, 7.1) among women with a higher proportion of PCB 203 in relation to the sum of PCBs 167 and 187. PCB exposure in pregnancy may be associated with increased risk for early breast cancer depending on the mixture that represents internal dose. It remains unclear whether individual differences in exposure, response to exposure, or both explain risk patterns observed.

Learning Areas:
Chronic disease management and prevention
Environmental health sciences
Public health biology
Public health or related public policy
Public health or related research

Learning Objectives:
1.Describe prospective association of PCB exposure during pregnancy and risk of subsequent breast cancer. 2. Explain how consideration of windows of susceptibility for breast cancer helps us to interpret the difference between this new study and prior findings in the field. 3. Formulate new testable hypotheses about mechanisms for the effects of persistent pollutants on breast cancer.

Keywords: Breast Cancer, Environment

Presenting author's disclosure statement:

Qualified on the content I am responsible for because: I am the research director and PI for research grants that supported this study. I have an MPH in Public Health Planning and a PhD in Epidemiology from UC Berkeley. I have been Director of the Child Health and Development Studies for over 10 years and a Senior Research Scientist at the Public Health Institute for >20 years.
Any relevant financial relationships? No

I agree to comply with the American Public Health Association Conflict of Interest and Commercial Support Guidelines, and to disclose to the participants any off-label or experimental uses of a commercial product or service discussed in my presentation.