None of the polymorphisms showed any significant impact on HNSCC risk by genotype alone, but we found interactions between drinking habit and MTHFR C667T (P = 0.04), MTR A2756G (P = 0.04) and MTRRA66G (P = 0.03) polymorphisms.
In conclusion, our data provide evidence that support the association between the MTR A2756G and MTRRG66A polymorphisms and SCCHN risk and that these two polymorphisms may have a joint effect on risk of SCCHN.