MTHFR and mucositis: Similar to G3-4 hepatotoxicity and nephrotoxicity, MTHFR C677T polymorphism was related to the incidence of G3-4 gastrointestinal toxicity and mucositis under the recessive genetic model (G3-4 gastrointestinal toxicity: OR = 1.85, 95%CI: 1.34–2.56; G3-4 mucositis: OR = 1.73, 95%CI: 1.31–2.28) (Table 2).