Evidence From Humans
 
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Polychlorinated biphenyls and their association with survival following breast cancer
Parada, H., Jr., Wolff, M. S., Engel, L. S., Eng, S. M., Khankari, N. K., Neugut, A. I., Teitelbaum, S. L., Gammon, M. D. Eur J Cancer. 2016. 56, 21-30.
Topic area
Environmental pollutant - PCBs
Study design
Population-based case-control; Case-only
Funding agency
NCI National Institutes of Environmental Health an
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
No analysis based on menopausal status
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
Breast cancer cases were from the Long Island Breast Cancer Study Project (LIBCSP), which included adult female residents of Nassau and Suffolk counties of New York. Cases in this study were age 20 or older, English-speaking, newly diagnosed with in situ or invasive breast cancer in 1996-1997, confirmed by a physician and medical records. Approximately 1102 cases (73.1% of LIBCSP cases) provided a blood sample; the analyses reported here were limited to cases with both blood and lipid levels available. Breast cancer mortality determined from National Death Index through 2011.
Comment about participation selection
In the LIBCSP, giving a blood sample was positively associated with being white, ever using alcohol, ever using HRT, ever having a mammography, and lactation history. Older women and former smokers were less likely to give blood. Lipid levels were only available for about half of the women who provided blood samples. This may limit generalizability of the findings to other populations.
Exposure Investigated
Exposures investigated
Lipid-standardized blood concentrations of PCBs. Congeners were analyzed individually and summed in groups based on those proposed by Wolff et al. 1997, as follows: Potentially estrogenic and persistent (Wolff et al. 1997 group 1B): 101, 174, 177, 187, 1
Exposure assessment comment
Blood samples were collected within three months after breast cancer diagnosis.
Breast cancer outcome investigated
Primary breast cancer survival
Confounders considered
Other breast cancer risk factors, such as family history, age at first birth, and hormone replacement therapy use, that were taken into account in the study.
Based on causal diagram: Age at diagnosis, education, BMI, parity/lactation
Genetic characterization included
If the study analyzed relationships between environmental factors and inherited genetic variations, this field will be marked “Yes.” “No”, if not.
No
Strength of associations reported
5-year breast cancer mortality among cases:

Potentially estrogenic PCB grouping, tertile 3 vs 1: aHR 0.90 (95% CI 0.39-2.09)
Potentially anti-estrogenic PCB grouping, tertile 3 vs 1: aHR 0.92 (95% CI 0.38-2.26)
Potentially anti-estrogenic, dioxin-like PCB grouping, tertile 3 vs 1: aHR 1.20 (95% CI 0.49-2.89)
Potentially CYP-inducer PCB grouping, tertile 3 vs 1: aHR 1.57 (95% CI 0.49-5.01)

15-year breast cancer mortality among cases:

Potentially estrogenic PCB grouping, tertile 3 vs 1: aHR 1.16 (95% CI 0.65-2.05)
Potentially anti-estrogenic PCB grouping, tertile 3 vs 1: aHR 0.72 (95% CI 0.37-1.42)
Potentially anti-estrogenic, dioxin-like PCB grouping, tertile 3 vs 1: aHR 1.00 (95% CI 0.55-1.81)
Potentially CYP-inducer PCB grouping, tertile 3 vs 1: aHR 1.13 (95% CI 0.57-2.26)

Analyses of individual congeners generally did not show significant associations, with the exception of PCB 174:
Results Comments
Analyses of individual congeners generally did not show significant associations, with the exception of PCB 174, which was significantly associated with both 5-year breast cancer mortality (T3 vs T1: HR 3.15 (95% CI: 1.23-8.09)) and 15-year breast cancer mortality (T3 vs T1: HR 1.88 (95% CI: 1.05-3.36)).
Author address
Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA. Electronic address: hparada@live.unc.edu. Department of Preventive Medicine, Mt. Sinai School of Medicine, New York, NY 10029, USA. Department of Epidemio
Reviewers Comments
A small fraction (<25%) of women had begun chemotherapy when blood samples were obtained; chemotherapy status could potentially affect PCB levels in blood and be associated with survival.
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