Association between sodium iodide symporter and differentiated Thyroid cancer: a meta-analysis of 9 studies.

Context: As many studies proved that sodium iodide symporter (NIS) plays a key role in radioactive iodide (RAI) therapy of thyroid cancer, however, a growing number of studies suggests that part of differentiated thyroid carcinomas (DTC) with overexpression of NIS are insensitive to RAI well.

Objective: The aim of this meta-analysis is to assess the expression of NIS in differentiated thyroid cancer, compared with normal thyroid tissue.

Data sources: PUBMED, Sinomed, CNKI, Wanfang and VIP were searched for relevant case-control studies up to now.

Study selection: Studies that concerning the qualitative expression NIS in DTC were included.

Data extraction: Working independently, authors used a standard form to extract data. For quality assessment, Newcastle-Ottawa Scale (NOS) were applied.

Data synthesis: Totally nine eligible studies included, involving 765 cases and 473 controls. The results revealed that the expression of NIS had a statistically increased in DTC, compared with controls (OddsRadio OR: 1.47, 95% CI: 1.12 to 1.94, Z=2.78, P=0.005). Since the existence of the significant heterogeneity, subgroup analysis and sensitivity analysis were performed and found that the heterogeneity came from the different criteria evaluate positive NIS expression (Liu 2008, Mu 2010) and the small simple size of the control group (Lin. J D2001). The heterogeneity disappeared or dropped to below 50% after remove these studies.

Conclusion: Our study shows that the expression of NIS is significantly increased in DTC, which could help explain the reason for individual with a poor response to RAI therapy. In other word, the reduced iodide uptake in thyroid cancer may not caused by the decreased expression of NIS, function of NIS protein or its post-transcriptional translocation might be the point.