[A case of far-advanced colon cancer with extraluminal progression that required urgent surgical treatment].

A 60-year-old man was admitted to our hospital because of right flank pain. An irregular cystic mass region with calcification was detected in his right abdomen on computed tomography( CT). On the fifth day after admission, the patient's abdominal pain suddenly worsened. Based on a diagnosis of panperitonitis, we performed an urgent laparotomy on the same day. A bulky tumor involving the right colon, duodenum, and retroperitoneum was found in his abdominal cavity. We performed right hemicolectomy and partial resection of the duodenum but could not completely excise the tumor. The manipulation caused a serious duodenal injury; and therefore, pyloric antrum transection, gastrojejunostomy, and cholecystostomy were performed to reduce the inflow of gastric content and bile. Histological examination of the surgical specimens revealed a moderately differentiated adenocarcinoma that originated from the ascending colon. Many cancer cells were detected in the excised margin; thus, the surgical maneuver of choice was absolute noncurative resection. If peritonitis had not been observed, preoperative chemotherapy would have been more appropriate.