Environment and Breast Cancer: Science Review
	Polychlorinated biphenyls and breast cancer: A congener-specific meta-analysis
	Leng, L., Li, J., Luo, X. M., Kim, J. Y., Li, Y. M., Guo, X. M., Chen, X., Yang, Q. Y., Li, G., Tang, N. J. Environ Int. 2016. 88, 133-41.
	 Topic area
Environmental pollutant - PCBs
Environmental pollutant - PCBs
	 Study design
Meta-analysis
Meta-analysis
	 Funding agency
National Natural Science Foundation of China Minis
National Natural Science Foundation of China Minis
Study Participants
	 Number of Cases
Not reported
Not reported
	 Menopausal Status
	
 The menopausal status of women included in this study is listed here.
	No analysis based on menopausal status
	Number  of Controls  
Not reported
Not reported
	 Country where study was conducted
This meta-analysis was conducted in China and revi
This meta-analysis was conducted in China and revi
	 Participant selection: Inclusion and exclusion criteria
	
 Criteria used to select participants in the study.
	16 studies with plasma/adipose PCB congener measurements and breast cancer outcomes published until 2015. Results were reported for 9 congeners that were measured by at least 2 studies.
	 Exposures investigated
Pooled OR/RRs were calculated with highest vs. lowest exposure measures extracted from studies, along with covariates, time of sample collection, and other study details, and are unitless. PCBs were grouped according to the following categories: potentia
Pooled OR/RRs were calculated with highest vs. lowest exposure measures extracted from studies, along with covariates, time of sample collection, and other study details, and are unitless. PCBs were grouped according to the following categories: potentia
	 How exposure was measured
Biological
Biological
	 Breast cancer outcome investigated
Primary incident breast cancer
Primary incident breast cancer
	 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.
	Confounders assessed vary across the original studies, but studies were rated based on confounders considered.
	 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
Potentially estrogenic:
PCB 187: OR 1.18 (95% CI 1.01-1.39)
Anti-estrogenic, dioxin-like:
PCB 118: OR 1.32 (95% CI 0.98-1.78)
PCB 138: OR 1.08 (95% CI 0.99-1.17)
PCB 156: OR 1.19 (95% CI 0.85-1.67)
PCB 170: OR 1.28 (95% CI 0.89-1.86)
CYP inducers:
PCB 99: OR 1.36 (95% CI 1.02-1.80)
PCB 153: OR 1.04 (95% CI 0.81-1.34)
PCB 180: OR 1.02 (95% CI 0.81-1.29)
PCB 183: OR 1.56 (95% CI 1.25-1.95)
Potentially estrogenic:
PCB 187: OR 1.18 (95% CI 1.01-1.39)
Anti-estrogenic, dioxin-like:
PCB 118: OR 1.32 (95% CI 0.98-1.78)
PCB 138: OR 1.08 (95% CI 0.99-1.17)
PCB 156: OR 1.19 (95% CI 0.85-1.67)
PCB 170: OR 1.28 (95% CI 0.89-1.86)
CYP inducers:
PCB 99: OR 1.36 (95% CI 1.02-1.80)
PCB 153: OR 1.04 (95% CI 0.81-1.34)
PCB 180: OR 1.02 (95% CI 0.81-1.29)
PCB 183: OR 1.56 (95% CI 1.25-1.95)
	 Results Comments
PCB concentrations assigned to dose-response reference groups were not uniform across studies.
PCB concentrations assigned to dose-response reference groups were not uniform across studies.
	 Author address
Department of Occupational and Environmental Health, School of Public Health, Tianjin Medical University, Tianjin 300070, China. Department of Toxicology, School of Public Health, Tianjin Medical University, Tianjin 300070, China. Department of Biomedical
Department of Occupational and Environmental Health, School of Public Health, Tianjin Medical University, Tianjin 300070, China. Department of Toxicology, School of Public Health, Tianjin Medical University, Tianjin 300070, China. Department of Biomedical
	 Reviewers Comments
Statistically significant positive associations were observed with PCB 187, PCB 99, PCB 183 exposures, which may indicate importance of CYP induction. PCB 187 is typically grouped as potentially estrogenic, but has also shown CYP2B induction.
Statistically significant positive associations were observed with PCB 187, PCB 99, PCB 183 exposures, which may indicate importance of CYP induction. PCB 187 is typically grouped as potentially estrogenic, but has also shown CYP2B induction.