Many studies were published to assess the associations of methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism with thyroid diseases, including thyroid cancer, but the results were controversial.
A comprehensive search was performed in the Pubmed, Embase, and Chinese Biomedical Database (CBM) databases or published studies investigating the associations of MTHFR C677T polymorphism with thyroid diseases. Odds ratios (OR) and 95% confidence intervals (95% CI) were used to assess the possible associations.
Nine studies with a total of 2421 individuals were finally included into the meta-analysis. Meta-analysis of nine studies showed that there was no association between MTHFR C677T polymorphism and thyroid diseases (OR (T vs. C) =1.09, 95% CI 0.94-1.26, p=0.25; OR (TT vs. CC) =1.04, 95% CI 0.75-1.42, p=0.83; OR (TT vs. CC/CT) =1.13, 95% CI 0.86-1.50, p=0.37; OR (TT/CT vs. CC) =1.22, 95% CI 0.88-1.68, p=0.24). Meta-analysis of studies on thyroid cancer showed that there was an obvious association between MTHFR C677T polymorphism and increased risk of thyroid cancer in Caucasians (OR (T vs. C) =1.30, 95% CI 1.03-1.65, p=0.03; OR (TT vs. CC) =2.06, 95% CI 1.04-4.10, p=0.04; OR (TT vs. CC/CT) =2.02, 95% CI 1.02-3.92, p=0.04). There was no obvious risk of publication bias in the meta-analysis.
This meta-analysis suggests that there is a significant association between MTHFR C677T polymorphism and thyroid cancer risk in Caucasians.