MTHFR and Decreased total neutrophil count: Simultaneously, the MTHFR 677G>A polymorphism had no statistical significance in 5-FU treatment in conjunction with the first and second cycles for all grades of anemia toxicity, the first cycle of grade 1-4 leukopenia, the second cycle for all grades of leukopenia, the first cycle of all grades of neutropenia, or second cycle grade 1-4 neutropenia.