Environment and Breast Cancer: Science Review

Evidence From Humans
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Dichlorodiphenyldichloroethene, polychlorinated biphenyls, and breast cancer among African-American and white women in North Carolina
Millikan, R., DeVoto, E., Duell, E. J., Tse, C. K., Savitz, D. A., Beach, J., Edmiston, S., Jackson, S., Newman, B. Cancer Epidemiology, Biomarkers and Prevention. 2000. 9:11, 1233-40.
Topic area
Environmental pollutant - Pesticide, DDE, PCBs
Study design
Population based case-control
Funding agency
Other: US NIH
Study Participants
Number of Cases
292 African-American; 456 white
Menopausal Status
The menopausal status of women included in this study is listed here.
Pre menopausal
Post menopausal
Number of Controls
270 African-American; 389 white
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
Participants of the Carolina Breast Cancer Study. First diagnosis in 1993- 1996 of invasive breast cancer in 24 counties of North Carolina reported to cancer registry; controls identified from motor vehicle and Medicare records
Comment about participation selection
Low participation rate for controls
Exposure Investigated
Exposures investigated
Lipid-adjusted plasma level, p,p'-DDE, total PCBs in thirds
Exposure assessment comment
Exposure measure may or may not correctly rank the exposures relevant to disease. Exposure measure is 10 years after the chemicals were banned and is subject to effects of time since exposure, parity and lactation, recent diet, weight loss. Consideration of selected organochlorines independent of other chemicals in this class may be problematic.
Statistical Analysis
Ethnic groups with separate analysis
If this study provided a separate analysis by ethnic or racial group, the groups are listed here.
African Americans
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, race, age squared, height, weight, body mass index, WHR, menopausal status, parity, breastfeeding, age at first full-term pregnancy, oral contraceptive use, HRT use, household income, education, smoking, alcohol consumption, dietary fruit, vegetables
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
Unconditional logistic regression; stratified by race, parity, history of breastfeeding, menopausal status, BMI, WHR, engaged in agriculture, lived or worked on farm, history of agricultural pesticide use
Strength of associations reported
Cases/controls; Adjusted OR (95% CI)
African American women
Tertile 2: 90/90; 1.12 (0.70-1.77)
Tertile 3: 113/90; 1.41 (0.87-2.29)
Total PCBs
Tertile 2: 97/90; 1.35 (0.84-2.16)
Tertile 3 116/90 1.74 (1.00-3.01)
No association with DDE among whites; little evidence of association with PCBs.
Associations are stronger among nulliparous women, parous women who never breastfed. Risk was not elevated for women in farming
Results Comments
Levels of DDE and total PCBs were higher among African-Americans than whites. Association between organochlorines and disease may be modified by obesity, among African-Americans. Increasing income is inversely associated with organochlorine levels among controls. Authors note that controls may be biased toward higher income women who have higher breast cancer risk for unknown reasons, and this may be confounding. Authors note that differential distribution of factors associated with organochlorine levels (race, parity, breastfeeding, obesity, SES) may contribute to differences in results from different study populations.
Author address
Department of Epidemiology, School of Public Health and Lineberger Comprehensive Cancer Center, School of Medicine, University of North Carolina at Chapel Hill, North Carolina 27599-7400, USA.