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Watch-and-Wait Protocol — SCE Medical Oncology MCQ

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HardGI CancersWatch-and-Wait ProtocolSCE Medical Oncology

Pretreatment testing shows complete DPD deficiency in a patient otherwise suitable for adjuvant fluoropyrimidine chemotherapy. What is the correct action?

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Correct answer: B — Do not give systemic 5-fluorouracil, capecitabine or tegafur

DPD is the rate-limiting enzyme for fluoropyrimidine catabolism. MHRA guidance says patients with known complete DPD deficiency must not receive systemic fluorouracil, capecitabine or tegafur because toxicity can be life-threatening or fatal. Changing formulation or empirically reducing the dose is not an accepted workaround for complete deficiency.

Reference: MHRA: DPD testing before systemic fluoropyrimidines. https://www.gov.uk/drug-safety-update/5-fluorouracil-intravenous-capecitabine-tegafur-dpd-testing-recommended-before-initiation-to-identify-patients-at-increased-risk-of-severe-and-fatal-toxicity