Alcohol consumption and risk of lung cancer: a pooled analysis of cohort studies

BACKGROUND: Although smoking is the primary cause of lung cancer, much is unknown about lung cancer etiology, including risk determinants for nonsmokers and modifying factors for smokers. OBJECTIVE: We hypothesized that alcohol consumption contributes to lung cancer risk. DESIGN: We conducted a pooled analysis using standardized exposure and covariate data from 7 prospective studies with 399,767 participants and 3137 lung cancer cases. Study-specific relative risks (RRs) and CIs were estimated and then combined to calculate pooled multivariate RRs by using a random-effects model. RESULTS: We found a slightly greater risk for the consumption of > or = 30 g alcohol/d than for that of 0 g alcohol/d in men (RR: 1.21; 95% CI: 0.91, 1.61; P for trend = 0.03) and in women (RR: 1.16; 95% CI: 0.94, 1.43; P for trend = 0.03). In male never smokers, the RR for consumption of > or = 15 g alcohol/d rather than 0 g alcohol/d was 6.38 (95% CI: 2.74, 14.9; P for trend < 0.001). In women, there were few never-smoking cases and no evidence of greater risk (RR: 1.35; 95% CI: 0.64, 2.87). Because of possible residual confounding by smoking, we performed sensitivity analyses by reclassifying the never smokers in the highest drinking category as former smokers. Resulting associations for alcohol consumption were somewhat attenuated, but P for trend = 0.05 for men, which was near the original P = 0.03. CONCLUSIONS: A slightly greater risk of lung cancer was associated with the consumption of > or = 30 g alcohol/d than with no alcohol consumption. Alcohol consumption was strongly associated with greater risk in male never smokers. Residual confounding by smoking may explain part of the observed relation.