A meta-analysis of alcohol drinking and oral and pharyngeal cancers. Part 1: overall results and dose-risk relation.

Alcohol consumption, together with tobacco, is the best recognised risk factor for oral and pharyngeal cancers (OPC), but several important aspects of this association need to be further explored. In order to provide up to date and more precise quantification of the association between alcohol drinking and OPC risk, we conducted a meta-analysis of available data. We performed a PubMed search of articles published up to September 2009, and we identified 43 case-control and two cohort studies presenting results for at least three categories of alcohol drinking, including a total of 17,085 OPC cases. We derived meta-analytic summary estimates using random-effects models, and taking into account correlation between estimates. We also performed a dose-risk analysis using non-linear random-effects meta-regression models. The pooled relative risk (RR) was 1.21 (95% confidence interval, CI, 1.10-1.33) for <or=1 drink per day, and rose to 5.24 (95% CI, 4.36-6.30) for heavy alcohol drinking (>or=4 drinks per day). The dose-risk analysis resulted in RR of 1.29 for 10g ethanol/day, 3.24 for 50g ethanol/day, 8.61 for 100g ethanol/day, and 13.02 for 125g ethanol/day. This meta-analysis provides more precise evidence of a gross excess of OPC risk for heavy alcohol drinkers. It also indicates an increased risk for moderate doses, i.e., <or=1 drink or 10g ethanol/day.