Environment and Breast Cancer: Science Review

Evidence From Humans
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Oxychlordane and trans-nonachlor in breast adipose tissue and risk of female breast cancer
Zheng, T., Holford, T. R., Tessari, J., Mayne, S. T., Zahm, S. H., Owens, P. H., Zhang, B., Ward, B., Carter, D., Zhang, Y., Zhang, W., Dubrow, R., Boyle, P. J Epidemiol Biostat. 2000. 5:3, 153-60.
Topic area
Environmental pollutant - Oxychlordane (OCD), Trans-nonachlor (TNC)
Study design
Hospital based case-control
Funding agency
Not reported
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.
Cases were histologically confirmed incident primary breast cancer patients at a university hospital. Controls were patients with histologically confirmed incident benign breast disease (BBD) (excluding atypical hyperplasia).
Exposures investigated
Lipid-adjusted breast adipose tissue concentrations of trans-nonachlor (TNC) and oxychlordane (OCD).
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, BMI, lifetime months of lactation, age at menarche, age at first full-term pregnancy, and race.
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
Comparison of lipid-adjusted breast adipose tissue concentrations of trans-nonachlor (TNC) and oxychlordane (OCD) between cases and controls. Analyses were also stratified by menopausal status, ER and PR status, cancer histology (ductal and lobular carcin
Strength of associations reported
Age-adjusted geometric mean concentration of oxychlordane (ppb):
cases: 36.4 (95% CI: 34.7-38.2)
controls: 38.0 (95% CI: 35.7-40.6)
Age-adjusted geometric mean concentration of trans-nonachlor (ppb):
cases: 55.5 (95% CI: 52.6-58.5)
controls: 58.1 (95% CI: 54.2-62.3)

OR for highest vs. lowest quartiles:
OCD: 0.7 (95% CI: 0.4-1.3)
TNC: 1.1 (95% CI: 0.6-1.9)
Results Comments
No differences found in breast adipose tissue concentrations of trans-nonachlor and oxychlordane between breast cancer cases and BBD controls. Age is an important confounder- since cases are older than controls, they have higher unadjusted TNC and OCD concentrations, but lower after adjusting for age. Matching for age is preferable to controlling for it in the analysis.
Author address
Yale University School of Medicine and Yale Cancer Center, New Haven, USA.