Is green tea drinking associated with a later onset of breast cancer?
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.
Dai
Qi
Q
Department of Medicine, Vanderbilt Epidemiology Center, Vanderbilt-Ingram Cancer Center, Vanderbilt School of Medicine, Nashville, TN 37203-1738, USA. qi.dai@vanderbilt.edu
Shu
Xiao-Ou
XO
Li
Honglan
H
Yang
Gong
G
Shrubsole
Martha J
MJ
Cai
Hui
H
Ji
Butian
B
Wen
Wanqing
W
Franke
Adrian
A
Gao
Yu-Tang
YT
Zheng
Wei
W
D000328:Adult; D017668:Age of Onset; D001141:Aromatase / Q000187:drug effects; D001943:Breast Neoplasms / Q000139:chemically induced / Q000453:epidemiology*; D002681:China; D005260:Female; D006801:Humans; D008875:Middle Aged; D013662:Tea
D013662:Tea; D001141:Aromatase