[A Case of Rectal Cancer with Portal Vein Tumor Thrombosis Successfully Treated with First-Line Panitumumab Monotherapy].

: The patient was a 66-year-old man with progressive rectal cancer and portal vein tumor thrombosis near the porta hepatis. A subileus further complicated the situation. Therefore, an abdominoperineal resection was performed. As the KRAS gene was the wild-type gene, we administered panitumumab monotherapy every 2 weeks after the operation. Two months after the operation, the tumor marker levels were normal and the tumor size was reduced. Hence, oral capecitabine, with 1-week administration followed by 1-week of rest, was added to the therapy. In the 12 months after the operation, panitumumab was stopped once, and treatment with capecitabine alone was continued in the same schedule. As of 26 months, the disease showed a partial response using capecitabine alone. We report our experience of a case of rectal cancer with portal vein tumor thrombosis that was successfully treated with panitumumab.