Environment and Breast Cancer: Science Review

Evidence From Humans
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Joint effects of nine polychlorinated biphenyl (PCB) congeners on breast cancer risk
Holford, T. R., Zheng, T., Mayne, S. T., Zahm, S. H., Tessari, J. D., Boyle, P. International Journal of Epidemiology. 2000. 29:6, 975-82.
Topic area
Environmental pollutant - PCB
Study design
Hospital based case-control
Funding agency
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
Pre menopausal
Post menopausal
Number of Controls
Controls: 186
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
Patients recruited in 1994-1997 in connection with breast-related surgery at Yale-New Haven Hospital, aged 40 -79. Cases were incident breast cancers; controls benign breast disease, excluding atypical hyperplasia. No previous cancer diagnosis.
Comment about participation selection
Controls with benign breast disease are not representative of a general population.
Exposure Investigated
Exposures investigated
Joint effects of 9 PCB congeners measured in breast adipose tissue. Lipid-adjusted.
Exposure assessment comment
Frequently detected congeners were selected to provide better measurement precision.
Statistical Analysis
Ethnic groups with separate analysis
If this study provided a separate analysis by ethnic or racial group, the groups are listed here.
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.
Age, body mass index, lifetime lactation, age at menarche, age at first full term pregnancy, gravidity, dietary fat intake, household income, fat levels of DDE.
Genetic characterization included
If the study analyzed relationships between environmental factors and inherited genetic variations, this field will be marked “Yes.” “No”, if not.
Description of major analysis
The possibility of differing vs. correlated effects of individual congeners was considered. Principle components and ridge regression techniques were applied.
Strength of associations reported
For total PCBs, the odds ratio is consistent with no effect. Odds ratios for individual congeners include some with positive (congener 180, 183) and some negative (153, 156) effects.
Adjusted OR (95%CI) for selected congeners: relative risk associated with a 10-ppb change in exposure
congener 153: 0.87 (0.78-0.98)
congener 156: 0.79 (0.64-0.99)
congener 180 1.14 (1.00-1.29)
congener 183 1.82 (1.12-2.98)
Results Comments
Congeners were highly correlated. Evidence that effects of congeners are not identical to each other. PCB 136, which is associated with breast cancer in Woolcott et al. was not tested.
Author address
Department of Epidemiology and Public Health, Yale University School of Medicine, New Haven, CT 06520-8034, USA.