Coffee Drinking and Risk of Lung Cancer-A Meta-Analysis

Previous epidemiologic results on coffee consumption and lung cancer risk have not been consistent. Furthermore, not all studies have addressed the potential role of tobacco as a confounder in this association. A meta-analysis was conducted to assess the effect of coffee consumption on lung cancer risk independent of tobacco use.

A systematic review and a meta-analysis based on random effects models were performed using studies from the PubMed and EMBASE databases, and the references from the retrieved articles. Included were 8 prospective cohorts and 13 case-control studies, which provided data for 19,892 cases and 623,645 non-cases, timeframe 1986-2015.

The meta-relative risk (RR) for coffee drinking, not controlling for tobacco smoking, was 1.09 [95% confidence interval (CI), 1.00-1.19], the reference group was never drinkers. There was significant heterogeneity among the study results (Q = 84.39, I² = 75.1%, Pheterogeneity < 0.001). Among non-smokers, coffee was not associated with lung cancer risk (RR, 0.92; 95% CI, 0.75-1.10), the reference group was never drinkers. The meta-RR for 1 cup per day increase, unadjusted for smoking, was 1.04 (95% CI, 1.03-1.05); the corresponding RR for non-smokers was 0.95 (95% CI, 0.83-1.09).

The pooled estimates indicated that when the potential confounding effect from smoking is controlled for, coffee drinking does not appear to be a lung cancer risk factor. Further pooled analyses, with larger non-smokers population size, are encouraged to confirm these results.

This study illustrates that the association between coffee consumption and lung cancer can be confounded by tobacco smoking. Cancer Epidemiol Biomarkers Prev; 25(6); 951-7. ©2016 AACR.