TLR3 gene polymorphisms in cancer: a systematic review and meta-analysis

INTRODUCTION: Recent studies examining the association of Toll-like receptor 3 (TLR3) gene polymorphisms with the risk of developing various types of cancer have reported conflicting results. Clarifying this association could advance our knowledge of the influence of TLR3 single nucleotide polymorphisms (SNPs) on cancer risk. METHODS: We systematically reviewed studies that focused on a collection of 12 SNPs located in the TLR3 gene and the details by which these SNPs influenced cancer risk. Additionally, 14 case-control studies comprising a total of 7997 cases of cancer and 8699 controls were included in a meta-analysis of 4 highly studied SNPs (rs3775290, rs3775291, rs3775292, and rs5743312). RESULTS: The variant TLR3 genotype rs5743312 (C9948T, intron 3, C > T) was significantly associated with an increased cancer risk as compared with the wild-type allele (odds ratio [OR] = 1.11, 95 % confidence interval [CI] = 1.00–1.24, P = 0.047). No such association was observed with other TLR3 SNPs. In the stratified analysis, the rs3775290 (C13766T, C > T) variant genotype was found to be significantly associated with an increased cancer risk in Asian populations. Additionally, the rs3775291 (G13909A, G > A) variant genotype was significantly associated with an increased cancer risk in Asians, subgroup with hospital-based controls, and subgroup with a small sample size. CONCLUSION: After data integration, our findings suggest that the TLR3 rs5743312 polymorphism may contribute to an increased cancer risk.