Single-nucleotide polymorphisms of the IL-12 gene lead to a higher cancer risk: a meta-analysis based on 22,670 subjects

The associations between interleukin-12 (IL-12) gene polymorphisms and cancer risk have been discussed extensively, with controversial results. Therefore, we conducted the present meta-analysis to better assess the potential roles of IL-12 gene variation in cancer occurrence. Eligible articles were found via PubMed, Medline, EMBASE, Google Scholar and CNKI. Odds ratios and 95% confidence intervals were used to evaluate the associations between IL-12 gene polymorphisms and cancer risk. Thirty-one studies with 10,749 cancer patients and 11,921 healthy subjects were included in the analyses. The overall results showed that cancer risk was increased by IL-12A rs568408 (GG versus GA + AA: P = 0.004; G versus A: P = 0.005) and IL-12B rs3212227 (AA versus AC + CC: P = 0.004; CC versus AA + AC: P = 0.03; A versus C: P = 0.007) polymorphisms. Further subgroup analyses for IL-12A rs568408 and IL-12B rs3212227 revealed that the positive results could be impacted by the ethnicity of the population, cancer type and/or genotyping methods. However, we failed to detect any significant associations between the IL-12A rs2243115 polymorphism and cancer risk in either the overall or the subgroup analyses. The current study suggests that certain IL-12 gene polymorphisms serve as biological markers of cancer susceptibility.