A population-based case-control study of lung cancer and green tea consumption among women living in Shanghai, China

Epidemiologic evidence regarding the association between the consumption of green tea and lung cancer is limited and inconclusive, although experiment al studies have shown consistently that tea preparations and tea polyphenol s may inhibit the induction of a variety of cancers, including lung cancer. In this population-based case-control study, we examined the association b etween past consumption of green tea and the risk of lung cancer. We identi fied 649 incident cases of primary lung cancer among women diagnosed from F ebruary 1992 through January 1994 using the population-based Shanghai Cance r Registry. We randomly selected a control group of 675 women from the Shan ghai Residential Registry, frequency-matched to the expected age distributi on of the cases. Green tea consumption was ascertained through face-to-face interviews. We estimated adjusted odds ratios (ORs) and 95% confidence int ervals (95% CIs) using unconditional logistic regression. Among nonsmoking women, consumption of green tea was associated with a reduced risk of lung cancer (OR = 0.65; 95% CI = 0.45-0.93), and the risks decreased with increa sing consumption. We found little association, however, among women who smo ked (OR = 0.94; 95% CI = 0.40-2.22). The inconsistency in the association b etween drinking tea and the risk of lung cancer reported in previous studie s may in part be due to inadequate control of confounding of active smoking .