Environment and Breast Cancer: Science Review

Evidence From Humans
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Adipose organochlorine concentrations and risk of breast cancer among postmenopausal Danish women
Raaschou-Nielsen, O., Pavuk, M., Leblanc, A., Dumas, P., Philippe Weber, J., Olsen, A., Tjonneland, A., Overvad, K., Olsen, J. H. Cancer Epidemiology, Biomarkers and Prevention. 2005. 14:1, 67-74.
Topic area
Environmental pollutant - Pesticide, organochlorine, PCB, DDE, DDT, HCB, chl
Study design
Nested case-control
Funding agency
Danish Medical Council, Danish Research Center for
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
Post menopausal
Number of Controls
Controls: 409
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
Post-menopausal women only. Cases were women of the Danish Diet, Cancer, and Health Cohort study who developed breast cancer during the follow-up period of the cohort study. For each of the cases, an age-matched control was randomly selected from the cohort, stratified on the certainty of the post-menopausal status, use of hormone-replacement therapy, and age at baseline.
Exposures investigated
Lipid-adjusted gluteal adipose tissue concentrations of 18 PCB congeners, as well as of DDE, DDT, HCB, chlordane, oxychlordane, nonachlor, HCH, oxychlordane, t-nonachlor, aldrin, dieldrin, endrin, heptachlorepoxide, and mirex.
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.
Previous benign breast tumor, level of education, BMI, alcohol consumption, nulliparity, number of deliveries, age at first delivery, duration of hormone replacement therapy, lifetime duration of 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.
Description of major analysis
Conditional logistic regression analysis was used to estimate the breast cancer rate ratios. Analyses were stratified according to estrogen-receptor status of the cancer.
Strength of associations reported
None of the organochlorines had gluteal adipose tissue concentrations that were significantly elevated in cases as compared to controls. Most levels were slightly higher in controls.

Inverse associations were seen between the risk of breast cancer and adipose concentrations of:
-hexachlorohexane (RR for highest quartile = 0.5, 95% CI: 0.3-0.9)
-oxychlordane (RR for highest quartile = 0.5, 95% CI: 0.3-0.9)
-trans-nonachlor (RR for highest quartile = 0.7, 95% CI: 0.5-1.2)
-hexachlorobenzene (RR for highest quartile = 0.5, 95% CI: 0.3-0.9)

The trend was inconsistent for:
-p,p'-DDT (RR for highest quartile = 0.6, 95% CI: 0.3-1.0)
-cis-nonachlor (RR for highest quartile = 1.5, 95% CI: 0.8-2.7)
-dieldrin (RR for highest quartile = 0.9, 95% CI: 0.5-1.6)

No significant trends were observed for any of the PCB congeners (RR for the highest quartile of the sum of all PCBs = 1.1, 95%CI : 0.7-1.7).

For both pesticides and PCBs, the risks tended to be lower among estrogen receptor-negative cancers. Several pesticides and PCB congeners showed significant negative associations with breast cancer risk among estrogen receptor-negative cancers. In estrogen receptor-positive tumors, the highest quartile RRs of PCB congeners 187, 138, 153, and 183 were non-significantly elevated.

Mean concentrations of DDE and PCBs were higher in smaller tumors and those with no lymph-node involvement.
Results Comments
Since this case-control study was nested in a prospective cohort study, the gluteal adipose organochlorine concentration measurement was taken several years prior to the development of breast cancer.
Author address
Danish Cancer Society, Institute of Cancer Epidemiology, Strandboulevarden 49, 2100 Copenhagen, Denmark. ole@cancer.dk
Reviewers Comments
A consistently decreased risk was observed for organochlorine exposure among estrogen receptor-negative tumors.