The association between tea intake and risk of oral, pharyngeal, and laryngeal carcinoma is still unclear. The aim of this meta-analysis was to quantify the effect of tea consumption on the incidence of oral, pharyngeal, and laryngeal cancer to provide a better understanding on this issue.
A literature search was conducted before January 2014 in MEDLINE and EMBASE databases. The relative risk (RR) estimates that extracted or calculated from all included studies were combined together. Given the existing heterogeneity in the study design and data source, a random-effects model was obtained.
A total of 20 articles were included in the quantitative synthesis. Fourteen RR estimates (11 from case-control studies and 3 from cohort studies) were pooled together and the result demonstrated that tea consumption reduced the incidence of oral cancer (RR=0.85; 95% CI 0.76-0.96). The summary RR of 4 observational studies (3 case-control studies and 1 cohort study) for pharyngeal cancer was 0.87 (95% CI 0.74-1.04). The association between tea consumption and oral and pharyngeal carcinoma was reported. The summary RR for laryngeal carcinoma was 1.05 (95% CI 0.70-1.57). The Begg's funnel plot and the Egger's test showed no evidence of publication bias.
Tea consumption was associated with decreased risk of oral cancer, while no association was detected with oral/pharyngeal, pharyngeal, or laryngeal cancer.