Environment and Breast Cancer: Science Review

Evidence From Humans
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The Effects of Green Tea Consumption on Incidence of Breast Cancer and Recurrence of Breast Cancer: A Systematic Review and Meta-analysis
Seely, D., Mills, E. J., Wu, P., Verma, S., Guyatt, G. H. Integr Cancer Ther. 2005. 4:2, 144-55.
Topic area
Diet - No
Study design
Funding agency
Lotte and John Hecht Memorial Foundation
Study Participants
Number of Cases
925 (includes men and women)
Menopausal Status
The menopausal status of women included in this study is listed here.
Premenopausal and postmenopausal combined
Number of Controls
115,601 (includes men and women)
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
In: Observational or randomized trials (though none existed) examining the effect of great tea consumption on breast cancer incidence or recurrence in men and women of all age. Ex: If studies did not not look specifically at green tea.
Comment about participation selection
Strong methodology for meta-analysis
Exposure Investigated
Exposure assessment comment
Measurements will vary between studies.
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.
Not considered: Menopausal status, family history of breast cancer, parity
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
Pooled RR and 95% CI
Results Comments
The pooled analysis does not definitively support the use of green tea in primary prevention of breast cancer; however, a trend toward risk reduction is demonstrated in nearly all the case-control and cohort studies.
Author address
Department of Clinical Epidemiology, Canadian College of Naturopathic Medicine, Toronto, Ontario, Canada, Institute of Medical Science, University of Toronto, Ontario, Canada. dseely@ccnm.edu.