Reversible encephalopathy following 5‐fluorouracil‐based chemotherapy in patients with dihydropyrimidine dehyrogenase deficiency

Abstract 5‐fluorouracil (5‐FU) is one of the most frequently used chemotherapy agents for the treatment of a number of solid cancers. We report two patients with advanced gastric cancer who developed acute encephalopathy after receiving chemotherapy composed of 5‐FU and oxaliplatin. One patient presented with altered consciousness and the other with generalized tonic clonic seizure. 5‐FU‐induced encephalopathy was suspected by clinical, radiological and electroencephalographic findings, and both patients had reduced expression of dihyropyrimidine dehydrogenase, the rate‐limiting enzyme responsible for the catabolism of 5‐FU. The neurological symptoms improved spontaneously, and did not recur in the following cycle of chemotherapy with the administration of a reduced dose of 5‐FU. We suggest that the early recognition of this adverse event can reverse 5‐FU‐induced neurological symptoms and a dose reduction of the offending drug can prevent the recurrence of 5‐FU induced encephalopathy.