Toxicity Associated with Capecitabine in Patients Suffering from Dihydropyrimidine Dehydrogenase Deficiency.

Dihydropyrimidine dehydrogenase (DPD) is a metabolic enzyme that is crucial in 5-fluorouracil (5-FU) degradation. A deficiency in it is associated with the occurrence of adverse events following fluoropyrimidine-based therapies. We describe a case of toxicity grade 5 after the administration of capecitabine and oxaliplatin in a patient with stage III colorectal cancer and DPD congenital deficiency, which was identified later. Several polymorphisms have been associated with the global toxicity of 5-FU; however, genetic tests are low in sensitivity and therefore they cannot as yet be used as prescreening techniques in clinical practice.