MTHFR and rectal cancer: For MTHFR rs3753584 T>C polymorphism, we found this polymorphism was associated with an increased risk of rectum cancer (CC+TC vs. TT: adjusted OR = 1.44, 95% CI = 1.04–2.00, P = 0.026; TC vs. TT: adjusted OR = 1.44, 95% CI = 1.04–2.00, P = 0.030) and of colon cancer (CC vs. TT+TC: adjusted OR = 3.74, 95% CI = 1.31–10.64, P = 0.014; CC vs. TT: adjusted OR = 3.63, 95% CI = 1.27–10.38, P = 0.016).