IL-17A (-197G/A) and IL-17F (7488T/C) gene polymorphisms and cancer risk in Asian population: a meta-analysis.

Interleukin (IL)-17 has been shown to play an important role in the pathogenesis of inflammation and cancer. The IL-17A (-197G/A) and IL-17F (7488T/C) polymorphisms have been extensively investigated with cancer risk, but individually published results have been inconclusive. The aim of this study was to clarify the effects of the IL-17A (-197G/A) and IL-17F (7488T/C) polymorphisms on cancer risk in Asian populations. Relevant studies were identified by searching databases extensively. The association between the IL-17A (-197G/A) and IL-17F (7488T/C) polymorphisms and cancer risk was assessed by odds ratios (ORs) together with their 95% confidence intervals (CIs). A total of 12 articles with adequate information satisfied our inclusion criteria; these included 12 studies, with 4,540 cases and 5,875 controls, of IL-17A (-197G/A) polymorphism and seven studies, with 1,960 cases and 3,226 controls, of IL-17F (7488T/C) polymorphism. In the overall analysis, the IL-17A (-197G/A) polymorphism was significantly associated with increased cancer risk (P<0.05), for all genetic models. However, there was no statistically significant association between IL-17F (7488T/C) and cancer risk (P>0.05), for any genetic models. Furthermore, stratification by cancer type revealed a significant correlation between the IL-17A (-197G/A) polymorphism and cancer risk for all cancer types. When stratified by source of controls, a significant correlation was observed between the IL-17A (-197G/A) polymorphism and cancer risk in the population-based control subgroup but not in hospital-based control subgroup. In conclusion, our meta-analysis provides evidence that the IL-17A (-197G/A) polymorphism might be associated with cancer risk, while no evidence suggested a significant association between IL-17F (7488T/C) polymorphism and cancer risk.