[A case in which dihydropyrimidine dehydrogenase deficiency was strongly suspected during adjuvant chemotherapy with capecitabine for colon cancer].

Severe toxicity in patients with a deficiency of dihydropyrimidine dehydrogenase(DPD), an enzyme that reduces fluoropyrimidine, is very rare, and reports on this condition are few. Accordingly, diagnosis is very difficult. The patient was 70-year-old man who was admitted for adjuvant chemotherapy with capecitabine(3,600mg/day)for rectal cancer. He was admitted to our hospital because of severe oral mucositis(grade 3)and hand-foot syndrome(grade 3). After hospitalization, he experienced complications with neutropenia(grade 4)and thrombocytopenia(grade 4). The patient died 25 days after the onset of chemotherapy. Despite the measurement of the DPD value in mononuclear cells of peripheral blood and urophanic uracil and dihydrouracil, we were unable to diagnose DPD deficiency. However, we suspected a partial deficiency of DPD on the basis of the clinical course.