Green tea consumption and risk for esophageal cancer: A systematic review and dose-response meta-analysis

Controversial results of the association between green tea consumption and risk for esophageal cancer (EC) were reported by previous meta-analysis. Thus, the aim of this study was to quantitatively investigate the association.

The Cochrane Library, PubMed, and EMBASE databases were searched for relevant studies. We used a "one-stage approach" with a restricted cubic spline model to summarize the dose-specific relationships between green tea and risk for EC. Odds ratios (ORs) were used to measure the effects. Fourteen studies were included with a total of 5057 ECs among 493 332 participants.

In the dose-response analysis, the summary OR for a 1 cup/d increase in green tea was 1.00 (95% confidence interval [CI], 0.95-1.04; I² = 77%). No nonlinearity association was observed between tea consumption and risk for EC (P = 0.71 for nonlinearity). In the subgroup of sex, the summary OR for a 1 cup/d increase in green tea was 1.03 (95% CI, 0.95-1.11, I² = 67%) for men and 0.79 (95% CI, 0.68-0.91; I² = 0%) for women.

Contrary to previous studies, based on current evidence, the present dose-response study suggested no association between green tea and risk for EC. However, there might be a protective effect of green tea in women. Notably, our conclusion might be influenced by limited studies and potential bias, such as dose of green tea assessment and select bias of case-control studies. Further larger number, prospective, and well-designed larger-scale studies are needed to provide more precise evidence, especially in women and more regions (United States and Europe).