Environment and Breast Cancer: Science Review

Evidence From Humans
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Green tea and the risk of breast cancer: pooled analysis of two prospective studies in Japan
Suzuki, Y., Tsubono, Y., Nakaya, N., Suzuki, Y., Koizumi, Y., Tsuji, I. Br J Cancer. 2004. 90:7, 1361-3.
Study design
2 Prospective cohort studies and a meta-analysis
Funding agency
Not reported
Study Participants
Number of Cases
1st cohort from 1984 - 1993: 103; 2nd cohort from 1990 - 1999: 119; meta-analysis: 222
Menopausal Status
The menopausal status of women included in this study is listed here.
Premenopausal and postmenopausal combined
Number in Cohort
1st cohort from 1984 - 1993: 14,409; 2nd cohort from 1990 - 1999: 20,595; pooled-analysis: 35,004
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
Ex: Missing responses or prior history of breast cancer
Exposure Investigated
How exposure was measured
Questionnaire, self-administered
Exposure assessment comment
Detail not given but had reasonably high level of validity and reproducibility
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.
Confounding was adequately controlled
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
Adjusted RR and 95% CI, highest versus lowest tertile
Strength of associations reported
1st cohort: 1.17 (0.67 - 2.05); 2nd cohort 0.61 (0.26 - 1.06); pooled-analysis: 0.84 (0.57 - 1.24)
Results Comments
No association between green-tea consumption and breast cancer incidence.
Author address
Department of Public Health and Forensic Medicine, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan.