A Case of Colon Cancer with DPD Deficiency That Showed Severe Myelosuppression by CapeOX Adjuvant Chemotherapy after Colon Resection

: A 57-year-old female patient received ileocecal colon resection because of colon cancer. Pathological findings showed pSSN2M0(pStage III b). After surgery, CapeOX was administered as an adjuvant chemotherapy. On day 13 of CapeOX treatment, severe oral mucositis and Grade 4 myelosuppression appeared, and the CapeOX treatment was immediately stopped. However, these adverse effects continued for 19 days, and she gradually recovered. The severe myelosuppression was caused bydeficiencyof DPD, which is a keyenzy me that metabolizes 5-FU. While DPD deficiencyis veryrare, we need to consider that 5-FU causes severe adverse events in patients with DPD deficiency.