[A Case of Advanced Gastric Cancer with Early Recurrence after Surgery Treated by Nivolumab]

The patient is a 65-year-old male. He underwent laparoscopic distal gastrectomy for advanced gastric cancer of the lower gastric body. Pathological findings were poorly differentiated adenocarcinoma, Stage ⅢC. The cancerous lesion extended over 15 cm and was extensively positive for margins on the oral side due to marked lymphatic invasion. Two months later, CT showed local peritoneal recurrence, so treatment with nivolumab+SOX was started. The recurrence was resolved, but due to appearance of anorexia 6 months later, the treatment was discontinued. His symptoms worsened further, and hospitalized to receive intravenous infusion. A marked decrease in blood cortisol and ACTH was observed, suggesting hypopituitarism as irAE. After steroid administration, the symptoms resolved quickly. Subsequently, nivolumab+SOX were administered, and a long-term complete response was achieved.