[A case of good response in a rectal cancer patient with decreased dihydropyrimidine dehydrogenase activity because of strict control of the 5-fluorouracil dose].

A 64-year-old man was diagnosed as having rectal cancer in August 2011. At the first medical examination, lymph node metastasis was observed as an abdominal para-aortic lesion. Therefore, before surgery was performed, full dose chemotherapy( capecitabine and oxaliplatin[ CapeOx] plus bevacizumab) was initiated. Immediately after the initiation of chemotherapy, the patient experienced severe side effects. We noticed that the patient had a dihydropyrimidine dehydrogenase (DPD) deficiency. When the patient recovered from the severe side effects, we observed that the abdominal metastasis had disappeared and the rectal cancer had shrunk. We thus performed low anterior resection. No chemotherapeutic regimen except for 5-fluorouracil( 5-FU) elicited a good response. Therefore, we strictly controlled the 5-FU dose, and because of this, the patient continues to have disease-free survival.