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. 2010 Jan;20(1):74-81.
doi: 10.1016/j.annepidem.2009.09.005.

Is green tea drinking associated with a later onset of breast cancer?

Qi Dai  1 , Xiao-Ou Shu, Honglan Li, Gong Yang, Martha J Shrubsole, Hui Cai, Butian Ji, Wanqing Wen, Adrian Franke, Yu-Tang Gao, Wei Zheng
Affiliations

Is green tea drinking associated with a later onset of breast cancer?

Qi Dai et al. Ann Epidemiol. 2010 Jan.

Abstract

Background: Studies have found that tea polyphenols inhibit aromatase. Because of the substantial difference in levels of estrogens between premenopausal and postmenopausal women, the relationship between tea consumption and breast cancer risk may depend on menopausal status.

Methods: We examined this hypothesis in the Shanghai Women's Health Study, a population-based cohort study of 74,942 Chinese women.

Results: We found a time-dependent interaction between green tea consumption and age of breast cancer onset (p for interaction, 0.03). In comparison with non-tea drinkers, women who started tea-drinking at 25 years of age or younger had a hazard ratio (HR) of 0.69 (95% confidence interval [CI]: 0.41-1.17) to develop premenopausal breast cancer. On the other hand, compared with non-tea drinkers, women who started tea drinking at 25 years of age or younger had an increased risk of postmenopausal breast cancer with an HR of 1.61 (95% CI: 1.18-2.20). Additional analyses suggest regularly drinking green tea may delay the onset of breast cancer.

Conclusions: Further studies are needed to confirm our findings.

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Conflict of interest statement

Competing interests: None of the authors have competing interests.

Figures

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Figure 1
Evaluation of proportional hazard assumption
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