Is Green Tea Drinking Associated With a Later Onset of Breast Cancer?
Received 30 April 2009; accepted 9 September 2009.
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.
dDivision of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD
Address correspondence to: Dr. Qi Dai, Vanderbilt Epidemiology Center, Institute for Medicine & Public Health, Sixth Floor, Suite 600, 2525 West End Ave., Nashville, TN 37203-1738. Tel: (615) 936-0707; fax: 615-936-8291.
ABSTRACT