Tea, coffee and oral cancer risk

Pooled individual-level data from nine case-control studies of head and neck cancers, including 5,139 cases and 9,028 controls.

Nine case-control studies were selected from the International Head and Neck Cancer Epidemiology (INHANCE) consortium pool of 33 studies, which included information on coffee (caffeinated and decaffeinated) and tea drinking and cancer of the oral cavity and pharynx. Seven studies also included information on laryngeal cancer.

Data from individual studies were checked for inconsistencies and pooled in a standardised way into a common database, including a range of sociodemographic, behavioural, lifestyle and health information. Data on consumption across studies were then converted into cups of de/caffeinated tea or coffee per day. The association between head and neck cancers and caffeinated coffee, decaffeinated coffee or tea intake was assessed by estimating the odds ratios (OR) and the corresponding 95% confidence intervals (95% CI) using a two-stage random-effects logistic regression model with the maximum likelihood estimator. Pooled ORs were also estimated with a fixed-effects logistic regression model. In addition, a test for heterogeneity among studies was conducted.

Caffeinated coffee intake was inversely associated with the risk of cancer of the oral cavity and pharynx: the ORs were 0.96 (95% CI, 0.94-0.98) for an increment of one cup per day and 0.61 (95% CI, 0.47-0.80) in drinkers of >4 cups per day versus non-drinkers. This latter estimate was consistent for different anatomic sites (OR, 0.46; 95% CI, 0.30-0.71 for oral cavity; OR, 0.58; 95% CI, 0.41-0.82 for oropharynx/hypopharynx; and OR, 0.61; 95% CI, 0.37-1.01 for oral cavity/pharynx not otherwise specified) and across strata of selected covariates. No association of caffeinated coffee drinking was found with laryngeal cancer (OR, 0.96; 95% CI, 0.64-1.45 in drinkers of >4 cups per day versus non-drinkers). Data on decaffeinated coffee were too sparse for detailed analysis, but indicated no increased risk. Tea intake was not associated with head and neck cancer risk (OR, 0.99; 95% CI, 0.89-1.11 for drinkers versus non-drinkers).

This pooled analysis of case-control studies supports the hypothesis of an inverse association between caffeinated coffee drinking and risk of cancer of the oral cavity and pharynx.