MTHFR and digestive system cancer: For MTHFR C677T, as shown in Table 2, after adjusting for potential confounders, compared to participants with the CC genotype, CT carriers conferred a substantially decreased trend for digestive system cancer risk (adjusted OR 0.71; 95% CI 0.52, 0.97, P = 0.034), as did TT carriers (adjusted OR 0.57; 95% CI 0.40, 0.82, P = 0.003; P for trend = 0.003).