Functional polymorphisms in two pre-microRNAs and cancer risk: a meta-analysis.

Since the identification of two functional polymorphisms in pre-miRNAs ﹛miR-146a rs2910164 and miR-196a2 rsll614913), a number of studies were published in the past several years to evaluate the associations between the two SNPs and cancer risk. However, the findings remain conflicting rather than conclusive. This meta-analysis included 12 published case-control studies, 5,916 cancer patients and 6,869 control subjects for SNP rs2910164, and 6,574 cases and 7,601 controls for SNP rsll614913. The allele C of rsll614913 was associated with a significantly increased risk of overall cancers (CC vs. TT: OR=1.18; 95%CI: 1.02-1.37; CT vs. TT: OR=1.11; 95% CI: 1.02-1.21; CC/CT vs. TT: OR=1.13; 95%CI: 1.04-1.23). However, we failed to find main effects for rs2910164 on overall cancer risk in different genetic models tested, while significantly increased risk was evident among cancers other than breast (GG/GC vs. CC: OR=1.30, 95%CI: 1.03-1.64; between study heterogeneity test: P = 0.007). The two functional SNPs may represent tissue specific effect on cancer susceptibility; however, additional well-designed large studies are required for the validation of the associations.