5-fluorouracil toxicity in the treatment of colon cancer associated with the genetic polymorphism 2846 A>G (rs67376798).

Colorectal cancer is the second most common cancer in Europe. Most antineoplastic regimens in first-line treatment involve 5-fluorouracil or oral prodrug capecitabine, combined with other antineoplastic agents such as oxaliplatin or irinotecan. It is well known that 5-fluorouracil and capecitabine are agents that can be toxic in cases of decreased dihydropyrimidine dehydrogenase activity because this enzyme is the main limiting factor in the metabolism of both agents. In this paper, we describe the case of a patient who developed severe toxicity to 5-fluouracil and who had a mutation in the gene encoding the enzyme dihydropyrimidine dehydrogenase.