Objective: To investigate the association between green tea consumption and the risk of endometrial cancer restricted to endometrial endometrioid adenocarcinoma (EEA) using a case-control design in Japan.
Methods: The cases were 152 patients with histopathologically diagnosed EEA, and the controls were 285 healthy women who were matched for age and area of residence with individual cases. The subjects completed a questionnaire regarding health-related lifestyle and reproductive history, and a food frequency questionnaire. Odds ratios (ORs) of EEA for frequency of green tea consumption were calculated by conditional logistic regression analysis.
Results: We observed a significant inverse association between green tea consumption and the risk of EEA with a dose-response relationship. The multivariate-adjusted OR of EEA was 0.77 (95% CI: 0.37-1.58) for those in the second quartile of green tea consumption (5-6 cups/week-1 cup/day), 0.61 (0.30-1.23) in the third quartile (2-3 cups/day), and 0.33 (0.15-0.75) in the highest quartile (> or = 4 cups/day), as referenced with those in the lowest quartile (< or = 4 cups/week; p for trend = 0.007). This inverse association was consistently observed regardless of the presence or absence of factors such as obesity and menopause.
Conclusion: Green tea consumption may be associated with a lower risk of EEA.