In patients with NK/T cell lymphoma and ANKL when the dose of MTX was 2.5-5 g/m2, with regard to MTHFR rs1801131, patients with the CC and AC genotypes had a significantly lower risk of developing hematopoietic toxicity than patients with the AA genotype had (p=0.044) (Table 13). This evidence concerns the gene MTHFR and extranodal nasal NK/T cell lymphoma.