Environment and Breast Cancer: Science Review

Evidence From Humans
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Exposure to Dichlorodiphenyltrichloroethane and the Risk of Breast Cancer: A Systematic Review and Meta-analysis
Park, J. H., Cha, E. S., Ko, Y., Hwang, M. S., Hong, J. H., Lee, W. J. Osong Public Health Res Perspect. 2014. 5:2, 77-84.
Topic area
Environmental pollutant - DDT, DDE
Study design
Funding agency
Ministry of Food and Drug safety, Osong, Korea
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
No analysis based on menopausal status
Number of Controls
Controls: 9280
Country where study was conducted
This meta-analysis was conducted in Korea and incl
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
Thirty-five retrospective case-control and nested case-control studies of DDT or DDT metabolites measured in biological samples, with relative risk estimates and 95% CIs available, published through August, 2012.
Comment about participation selection
No study quality review was performed and no details about participant selection for the lindividual studies were provided.
Exposures investigated
DDT and DDT metabolites in DDT or DDT metabolites
Breast cancer outcome investigated
Prmary 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.
Not reported overall or for individual studies
Genetic characterization included
If the study analyzed relationships between environmental factors and inherited genetic variations, this field will be marked “Yes.” “No”, if not.
Strength of associations reported
Meta-OR for DDE: 1.03 (95% CI 0.95-1.12)

Meta-OR for DDE by study decade:
1960s (2 studies): OR 1.30 (95% CI 0.95-1.77)
1970s (2 studies): OR 0.92 (95% CI 0.73-1.17)
1980s (4 studies): OR 0.87 (95% CI 0.69-1.09)
1990s (27 studies): OR 1.03 (95% CI 0.94-1.24)
2000s (2 studies): OR 1.28 (95% CI 0.44-3.71)
Results Comments
Summary estimate was based on approach that weighted log(OR) of each study by a function of its variance. However complete lack of description about what ORs from each study represent (i.e. units, reference group) and lack of information about confounders considered across studies greatly limits interpretation.
Author address
Food Safety Risk Assessment Division, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, Osong, Korea. Department of Preventive Medicine, College of Medicine, Korea University, Seoul, Korea.
Reviewers Comments
We could not locate some of the ORs listed for the individual studies in the original articles (e.g. the effect estimate quoted for Cohn, 2007, OR: 1.29 (95% CI: 0.85-1.96)