Alcohol consumption and lung cancer risk among Japanese: a meta-analysis.

t is unknown what biologic mechanism may be responsible for the harmful effects of alcohol, though several have been suggested. Alcohol consumption is an established risk factor for cancers of the oral cavity, pharynx, larynx, esophagus and liver. However, epidemiologic studies have not provided consistent evidence on the effect of alcohol consumption on the risk of lung cancer. To evaluate the role of alcohol consumption in the risk of lung cancer among Japanese, the authors performed a meta-analysis of existing epidemiological studies. The authors first examined whether current alcohol consumption could potentially increase the risk of lung cancer without considering confounding factors. The summary risk estimate based on then random effects model for current consumption was 0.65 (95% confidence interval (CI) = 0.53 - 0.77). This risk estimate might be biased due to uncontrolled confounders, especially smoking cigarettes which is highly correlated with alcohol consumption. After adjustment for cigarette smoking, the summary risk estimate based on the random effects model for current alcohol consumption was no longer statistically significant (summary risk = 1.00, 95% CI = 0.73 - 1.26). Our results do not indicate that alcohol consumption serves as a major risk factor for lung cancer among Japanese. Additional studies with detailed assessments of alcohol consumption and potential confounding factors will undoubtedly lead to a better understanding of the role of alcohol consumption in lung cancer development.