Coffee is one of the most popularly consumed beverages worldwide. Many epidemiological studies have investigated the association between coffee consumption and lung cancer risk, but the results are inconsistent. Hence, we conducted a systematic analysis of relevant population-based studies to examine this association and derive a more precise estimation.
The Cochrane library, PubMed and Embase databases were searched to identify studies published through Mar 2015 that met the predetermined inclusion criterion. Seventeen studies (5 cohort and 12 case-control studies) involving 12 276 cases and 102 516 controls were included.
The summary odds ratio (OR) of lung cancer was 1.17 (95% confidence interval (CI): 1.03-1.33) for coffee drinkers compared with nondrinkers and 1.31 (95% CI: 1.11-1.55) for the highest category of coffee consumption compared with the lowest category. Compared with nondrinkers, the pooled ORs for lung cancer were 1.10 (95% CI: 0.92-1.31) for ⩽1 cup per day, 1.10 (95% CI: 0.93-1.30) for 2-3 cups per day and 1.20 (95% CI: 1.02-1.39) for ⩾3 cups per day. Further analysis showed that the ORs for hospital-based case-control studies, population-based case-control studies and prospective cohort studies were 1.36 (95% CI: 1.10-1.69), 0.99 (95% CI: 0.77-1.28) and 1.59 (95% CI: 1.26-2.00), respectively. Significant associations for high coffee intake with increased risk of lung cancer were observed in men (OR=1.41 95% CI: 1.21-1.63), but not in women (OR=1.16, 95% CI: 0.86-1.56), in American (OR=1.34 95% CI: 1.08-1.65) and Asian populations (OR=1.49 95% CI: 1.28-1.74), but not in European populations (OR=1.12, 95% CI: 0.74-1.67), and in smokers (OR=1.24, 95% CI: 1.00-1.54), but not in nonsmokers (OR=0.85, 95% CI: 0.64-1.11). Particularly over the last 5 years, studies have consistently indicated that lung cancer risk is significantly increased by 47% in the population with the highest category intake of coffee compared with that with the lowest category intake (OR=1.47, 95% CI: 1.21-1.79).
The present study suggested that coffee intake was associated with an increased risk of lung cancer.