Interleukin-6 -634C/G polymorphism is associated with lung cancer risk: a meta-analysis

Several studies have examined the associations of polymorphisms in interleukin-6 (IL6) with lung cancer (LC) risk. However, the results were conflicting. Thus, a meta-analysis was conducted to determine the relationship between IL6 polymorphisms and LC risk. Databases including PubMed, EMBASE, Wanfang, and China National Knowledge Infrastructure (CNKI) were searched. Data were extracted and pooled odds ratios (OR) with 95% confidence intervals (CI) were calculated. Thirteen studies were included in this meta-analysis. Overall, a significant association between IL6 -634C/G polymorphism and LC susceptibility was observed for GG + CG vs. CC (OR = 1.33, 95% CI 1.20-1.47, P < 0.00001). This polymorphism was also significantly associated with LC risk in Asians (OR = 1.33, 95% CI 1.20-1.47, P < 0.00001), female patients (OR = 1.30, 95% CI 1.11-1.52, P = 0.0009), male patients (OR = 1.25, 95% CI 1.03-1.52, P = 0.02), non-small cell lung cancer patients (OR = 1.21, 95% CI 1.03-1.41, P = 0.02), small cell lung cancer patients (OR = 1.91, 95% CI 1.23-2.97, P = 0.004), smokers (OR = 1.42, 95% CI 1.21-1.65, P < 0.0001), and non-smokers (OR = 1.32, 95% CI 1.13-1.53, P = 0.0003), respectively. No significant result was found for IL6 -174C/G polymorphism. This meta-analysis suggested that IL6 -634C/G polymorphism was a risk factor for LC.