[Ileal Ulcer Perforation Induced by S-1 Chemotherapy for Gastric Cancer-A Case Report].

Gastrointestinal perforation during chemotherapy for gastric cancer is an infrequent but important adverse event. We report a case of ileal ulcer perforation induced S-1 chemotherapy for gastric cancer. A 73-year-old male underwent total gastrectomy in December 2020(palliative surgery)and S-1 chemotherapy was initiated in January 2021. The treatment was well tolerated until late March, when he presented with sudden abdominal pain and fever. He was diagnosed with perforation of the gastrointestinal tract and acute generalized peritonitis. Emergency laparotomy revealed a 2-mm perforation in the ileum, approximately 30 cm proximal to the terminal ileum. About 7 cm of ileum including the perforated area was partially resected. Histopathological analysis confirmed a Ul-Ⅳ ulcer with granulation tissue and severe inflammation. Based on clinical and pathological findings, the perforation was attributed to S-1-induced small intestinal ulceration. The patient subsequently received up to fourth-line chemotherapy. He survived for 15 months after the initial surgery.