First case report of neoadjuvant gemcitabine and S-1 for locally advanced unresectable duodenal adenocarcinoma

BACKGROUND: The usefulness of neoadjuvant chemotherapy for patients with duodenal adenocarcinoma remains unclear. We report the case of a successfully resected duodenal adenocarcinoma managed by neoadjuvant chemotherapy using gemcitabine and S-1. CASE PRESENTATION: A 72-year-old female presented with a one-week history of abdominal bloating and vomiting after meals. Esophagogastroduodenoscopy revealed a circumferential epithelial lesion in the second portion of the duodenum. Abdominal computed tomography scan revealed thickened walls and narrowing of the duodenum. Further, an adenocarcinoma was noted on biopsy. Though she was diagnosed with duodenal adenocarcinoma, pancreatic cancer could not be completely ruled out. Therefore, she underwent neoadjuvant chemotherapy using gemcitabine and S-1 after bypass surgery. After six chemotherapy cycles, the tumor significantly reduced in size. Further, lymph nodes and distant metastases were not noted on abdominal computed tomography. The patient underwent pancreaticoduodenectomy. Pathological examination revealed a 0.5-mm lesion and surrounding fibrosis at the duodenum, distal from the ampulla of Vater and the pancreas. Her postoperative course was almost uneventful, and she was discharged on the 31st postoperative day. The patient was followed up and had no tumor recurrence at 24 months after surgery. CONCLUSION: Neoadjuvant chemotherapy with gemcitabine and S-1 was useful in reducing the size of a duodenal adenocarcinoma. This finding would aid physicians in managing patients that present with a similar presentation.