A 50-year-old female became aware of skin yellowing and consulted another hospital where she was diagnosed intraoperatively with duodenal cancer because of lymph node metastases around the aorta. Endoscopy revealed type IIa + IIc cancer distal to the duodenal papilla, and biopsy allowed a diagnosis of well-differentiated adenocarcinoma. Computed tomography revealed a large number of lymph node metastases around the aorta and in the left supraclavicular cavity. The patient was given many regimens of chemotherapy, mainly containing S-1, and multidisciplinary treatment, and achieved long-term survival for 6 years and 1 month. This is a valuable case suggesting the usefulness of this therapeutic approach. In view of the fact that duodenal cancer is a relatively rare disease and the possibility that the incidence of this disease may increase in the future, it seems essential to collect additional data from multicenter prospective studies towards the goal of establishing a standard method of treatment for this disease.