The Capsule Endoscopy Findings in S-1-induced Enteritis with Severe Diarrhea during Adjuvant Chemotherapy for Gastric Cancer (with Video)

Although S-1 chemotherapy is used widely as postoperative adjuvant chemotherapy for gastric cancer, some patients experience diarrhea during treatment. The patient was a 39-year-old woman who underwent distal gastrectomy for gastric cancer and who had started S-1 chemotherapy as postoperative adjuvant chemotherapy 1 week before her presentation. She experienced severe diarrhea immediately after starting the course of S-1 tablets. Capsule endoscopy revealed severe S-1-induced enteritis with extensive mucosal injury in the ileum and red intestinal fluid due to the oozing of blood in the ileum. After reducing the dosage of S-1, her diarrhea became milder, and she was able to continue S-1 chemotherapy.