A 67-year-old man visited our hospital with a history of continuous hematochezia leading to hemorrhagic shock.An abdominal computed tomography scan re-vealed a large mass in the ascending colon invading the duodenum and pancreatic head as well as extra-vasation of blood from the gastroduodenal artery(GDA) into the colon.Colonoscopy revealed an irregular ulcerative lesion and stenosis in the ascending colon.Therefore,right hemicolectomy combined with pylorus-preser ving pancreaticoduodenectomy was performed.Histologically,the tumor was classified as a moderately differentiated adenocarcinoma.Moreover,cancer cells were mainly located in the colon but had also invaded the duode-num and pancreas and involved the GDA.Immunohistochemically,the tumor cells were positive for cytokeratin(CK)20 and carcinoembryonic antigen(CEA)but not forCK7 and carbohydrate antigen(CA)19-9.The patient died 23 d after the surgery because he had another episode of arterial bleeding from the anastomosis site.Although En bloc resection of the tumor with pancreatico duodenectomy and colectomy performed for locally advanced colon cancer can ensure long-term survival,patients undergoing these procedures should be carefully monitored,particularly when the tumor involves the main artery. A 67-year-old man visited our hospital with a history of continuous hematochezia leading to hemorrhagic shock. Anumbdominal computed tomography scan re-vealed a large mass in the ascending colon invading the duodenum and pancreatic head as well as extra-vasation of blood from the gastroduodenal artery (GDA) into the colon. Colonoscopy revealed an irregular ulcerative lesion and stenosis in the ascending colon. Beforefore, right hemicolectomy combined with pylorus-preser ving pancreaticoduodenectomy was performed. Histologically, the tumor was classified as a moderately differentiated adenocarcinoma. Moreover, cancer cells were mainly located in the colon but had also invaded the duode-num and pancreas and involved the GDA. Immunohistochemically, the tumor cells were positive for cytokeratin (CK) 20 and carcinoembryonic antigen (CEA) but not forCK7 and carbohydrate antigen (CA) 19-9. The patient died 23 d after the surgery because he had another episode of arterial bleeding from the anastomosis site. Altho ugh En bloc resection of the tumor with pancreatico duodenectomy and colectomy performed for advanced advanced cancer cancer can ensure long-term survival, patients undergoing these procedures should be carefully monitored, particularly when the tumor involves the main artery.