A Case of Hyperammonemic Encephalopathy following mFOLFOX6 plus Panitumumab Therapy for Rectal Cancer

An 80-year-old man underwent laparoscopic rectal high anterior resection with perineal dissemination for the management of RS rectal cancer. Following the diagnosis of RS rectal cancer with muc, pT4a, N3(14/15), M1c, P1, pStage Ⅳc, RAS/BRAF: wild type, treatment was initiated with mFOLFOX6 plus panitumumab(Pmab). Laboratory examination on admission revealed mild renal dysfunction(Cr 1.45 mg/dL). The patient became confused on day 3 of chemotherapy(JCS Ⅲ-200). Furthermore, laboratory findings revealed a serum ammonia level of 338μg/dL. He was diagnosed with 5-FU- induced hyperammonemic encephalopathy. Discontinuation of high-dose 5-FU and branched-chain amino acid solutions improved his mental status and decreased serum ammonia levels. We switched his chemotherapy regime to CPT-11 plus Pmab, but it was discontinued after 1 course on his request.