Background: Several studies have indicated an association between tumor necrosis factor-alpha (TNF-α) or interleukin(IL)-6 gene polymorphisms and the risk of lung cancer. However, the conclusions remain controversial. The aim of this study is to examine the association of tumour necrosis factor-alpha (TNF-α) and interleukin-6（IL-6） gene polymorphisms with the risk of developing lung cancer.
Methods: We searched several electronic databases, including PubMed and Excerpt Medica Database (EMBASE). The effects of three polymorphisms, TNF-α-308G/A, IL-6-174G/C and IL-6-634C/G, were evaluated. The pooled odds ratio (OR) with 95% confidence interval (CI) was calculated by RevMan software. Heterogeneity was also assessed.
Results: For a total of 17 studies involving 4,094 cases and 4,988 controls, were identified in this meta-analysis. Based on our results, we found an association between the TNF-α-308G/A polymorphism and lung cancer risk under the dominant model (GG+GA vs. AA, OR = 0.60, 95% CI: 0.40 to 0.89). For the IL-6-174G/C polymorphisms, the pooled ORs (95% CI) of GG/GC vs. CC, GG vs. GC/CC, GC vs. CC, and GG vs. CC were 1.22 (1.02 to 1.46), 1.22 (1.01 to 1.48), 1.22 (1.01 to 1.48), and 1.12 (0.87 to 1.44), respectively. For the IL-6-634C/G polymorphisms, the pooled ORs (95% CI) of CC/CG vs. GG, CC vs. CG/GG, and C vs. G were 1.04 (0.68 to 1.58), 0.69 (0.57 to 0.85), and 0.79 (0.67 to 0.93) respectively.
Conclusions: The results of our analysis of these IL-6 polymorphisms revealed an association between IL-6 and lung cancer risk. This association, however, was not as strong as the association between TNF-α-308G/A polymorphisms and lung cancer risk. Because the current study was limited in sample size, further studies are needed to reveal more precise associations.