Association between the rs1800795G > C polymorphism in the promoter of interleukin-6 gene and bladder cancer

Interleukin-6 (IL-6) is an inflammatory cytokines that plays a role in the development of cancer. Several studies have examined the relationship between the IL-6 -174G>C polymorphism and bladder cancer, but these results are inconclusive. Therefore, we conducted a meta-analysis to explore the association between IL-6 -174G>C polymorphism and bladder cancer risk. A comprehensive literature search was performed to identify eligible studies regarding the IL-6 -174G>C polymorphism and bladder cancer. Effect sizes under fixed-and random-effects models were calculated using odds ratios (ORs) with 95% confidence intervals (CIs). Finally, five case-control studies were included in the subsequent analyses. In the fixed-effect analysis, significantly higher bladder cancer risks of 1.20 (95% CI = 1.07-1.36) and 1.30 (95% CI = 1.08-1.56) were found for the dominant model (C/C+ G/C vs. G/G) and recessive model (C/C vs. G/C+ G/G), respectively. Especially for the Asian population, significantly greater bladder cancer risks of 1.63 (95% CI = 1.32-2.00) and 1.54 (95% CI = 1.07-2.21) were observed for the dominant model (C/C+ G/C vs. G/G) and the recessive model (C/C vs. G/C+ G/G), respectively. Non-significantly increased risks of bladder cancer were observed for the dominant and recessive models under the random-effects analysis. The major findings of this meta-analysis suggest that IL-6 -174G>C polymorphism is significantly associated with bladder cancer risk in the Asian population. Further studies with a larger sample size are needed to validate the effects of IL-6 polymorphisms on bladder cancer risk.