Objective To assess the effect of tea consumption on incidence of gingival carcinoma.

Methods A case-control study including 121 gingival carcinoma patients confirmed by pathological diagnoses and 363 gender-age frequency matched controls were enrolled in Fujian province from December 2010 to March 2016. Unconditional logistic regression was used to calculate adjusted odds ratios (ORs) and corresponding 95% confidence intervals (CIs) to assess the effects of tea related variables on gingival carcinoma and interaction analysis.

Results Tea consumption was associated with decreased risk of gingival carcinoma(OR=0.51, 95%CI: 0.29-0.75). Moreover, with a greater daily quantity and a longer duration of tea-drinking, the risk of gingival carcinoma was reduced (all P_trend<0.05). Furtherly, age of tea drinking initiation (years) more than 25, moderate concentration as well as temperature of tea, drinking green tea and oolong tea were also showed decreased the risk of gingival carcinoma. The stratificated analysis indicated that the protective effect of tea drinking was more evident among non-tobacco smokers(OR=0.40, 95%CI: 0.17-0.96), but no significance was observed in the alcohol drinkers or non-alcohol drinkers. No significantly multiplicative interaction was observed between smoking and tea. The same re sult was found between alcohol drinking and tea.

Conclusion Tea consumption plays a protective effect on gingival carcinoma. Moreover, there is dose-response relationship between daily quantity or duration of tea-drinking and risk of gingival cancer.