[Report of a Case of Unresectable Advanced Gastric Cancer with Long-Term Survival on Chemotherapy Alone]

A 68-year-old male presented with upper abdominal pain and was referred to our hospital after endoscopy revealed a primary tumor in the gastric antrum. He was diagnosed with unresectable advanced gastric cancer(cT4b[liver, pancreas]N+M1[PUL], cStage ⅣB). S-1 and oxaliplatin were selected as first-line chemotherapeutic agents. After 2 courses, a CT scan showed that the primary tumor and lymph nodes had shrunk, but there was no change in the pulmonary metastases. After 7 courses, oxaliplatin was discontinued due to peripheral neuropathy, and only S-1 was subsequently administered as a single agent. Endoscopy revealed only a scar at the primary tumor site, without malignant findings on biopsy. Seven years after treatment, he continued with only S-1. The lung metastases remained unchanged, but the primary tumor and lymph nodes continued to disappear.