Methylation of sodium iodide symporter promoter correlated with aggressiveness and metastasis in papillary thyroid carcinoma: a meta-analysis.

BACKGROUND Methylation of sodium iodide symporter promoter has been reported to increase the incidence of papillary thyroid carcinoma (PTC). In this meta-analysis stratified via methylation of sodium iodide symporter promoter, we evaluate the relationship between methylation of sodium iodide symporter promoter and PTC. The association between methylation with aggressiveness and metastasis potential of PTC is also discussed. METHODS We searched electronic databases for original articles and references of included studies both in English and Chinese from 1966 to 2014. Two reviewers selected the case-control study and extracted data from relevant literature independently. RESULTS Seven articles, including 360 cases and 268 controls, were involved in this meta-analysis. The prevalence of PTC in patients with methylated sodium iodide symporter promoter was significantly higher than those with non-methylated promoter (OR=7.36, 95% CI: 4.25-12.74, P<0.001). Stratified analysis showed that PTC patients with multiple lesions, capsule invasion and lymphatic metastasis had significantly higher rates of methylation (OR=2.22, 95% CI: 1.12-4.41, P=0.02; OR=2.14, 95% CI: 1.12-4.08, P=0.02; OR=3.56, 95% CI: 1.97-6.46, P<0.0001). But no relationship was found among the methylation of sodium iodide symporter and age, gender and size of tumor. CONCLUSIONS The methylation of sodium iodide symporter promoter is related with PTC and its aggressive and metastatic potential. Due to the limited sample size, more clinical researches should be taken in the future.