Is Green Tea Drinking Associated With a Later Onset of Breast Cancer?

Background

Studies have found that tea polyphenols inhibit aromatase. Due to the substantial difference in levels of estrogens between pre- and post-menopausal 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% 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.