MTHFR and gastric cancer: In addition, we conducted a quality assessment of the included literature and the results showed that 26 studies with a high-quality and 13 medium-quality studies and 4 low-quality studies studied the association between MTHFR C677T and risk of GC; In contrast, of the studies on MTHFR A1298C and the risk of GC, 12, 6 and 1 rated as high, medium and low quality, respectively.