Purpose: The association between Interleukin-17A (IL- 17A) G197A and IL-17F T7488C polymorphisms and risk for specific forms of cancer is inconclusive. We conducted a meta-analysis of all published studies to estimate the association of IL-17A G197A and IL-17F T7488C polymorphisms and cancer risk.
Methods: A systematic computerized searching of the PubMed and Web of Science databases was performed for relevant publications. Data were extracted and statistical analysis was performed using RevMan 5.2 software.
Results: Eight eligible case-control studies with 3,323 cases and 3,974 controls were included into this meta-analysis. The pooled odds ratios (ORs) showed that the IL-17A G197A polymorphism increased the risk for specific forms of cancer under the following genetic models: A vs G (OR = 1.31, 95 % CI 1.13-1.52, Ph - 0.02); AA vs GG (OR = 1.81, 95 % CI 1.30- 2.52, Ph = 0.007); AA /AG vs GG (OR = 1.26, 95 % CI 1.11- 1.43, Ph = 0.79); AA vs AG / GG (OR = 1.72, 95 % CI 1.16-2.53, Ph <0.0001). However, the IL-17F T7488C polymorphism did not increase or decrease cancer risk under all genetic models. Stratified analysis by cancer type revealed that the IL-17A G197A polymorphism may increase the risk of gastric cancer. Further subgroup analysis by country indicated that there was a statistically increased cancer risk in China.
Conclusions: The present meta-analysis showed the IL- 17A G197A polymorphism is associated with a significantly increased risk for specific forms of cancer, especially in gastric cancer. Subsequent studies with large sample size are warranted to validate this association.