Can dihydropyrimidine dehydrogenase impact 5-fluorouracil-based treatment?

More than 80% of an administered 5-fluorouracil (5-FU) dose is degraded by dihydropyrimidine dehydrogenase (DPD), making it an important regulator of this commonly used anticancer agent. The high variation in population DPD activity, association with 5-FU activity, and development of DPD inhibitors have all contributed to the current focus on this enzyme. This review details the impact of DPD on 5-FU pharmacology, catalogues recent information on DPD mutations, evaluates the case for tumour DPD as a source of 5-FU resistance and introduces the clinical case for DPD inhibitors as a mechanism for the use of oral fluoropyrimidine therapies.