Parenteral 5-fluorouracil (5-FU) is part of the standard treatment for various malignant
tumors (such as colorectal cancer, pancreatic cancer, gastric cancer, breast cancer, and
head and neck cancers) and is most often used in combination with other chemotherapy
agents.If uracil levels are used to determine
DPD phenotype, the phenotype results should be interpreted cautiously in patients
with moderate or severe renal impairment.If severe toxicity does not
occur, subsequent doses may be increased, as the efficacy of conventionally
lower doses has not been established.Patients with impaired DPD enzyme activity have an increased risk of severe
or life-threatening toxicity when treated with 5-FU or any of its prodrugs.Dihydropyrimidine dehydrogenase (DPD) is an enzyme that affects the degradation rate of 5-FU.