[A Case of Advanced Gastric Cancer with Para-Aortic Lymph Node Metastasis Treated with Conversion Surgery after S-1 plus Oxaliplatin Chemotherapy].

A 71-year-old man was diagnosed as having Type 2 gastric cancer(tub2, HER2-negative). Abdominal computed tomography( CT)revealed bulky metastatic lymph nodes around the stomach and para-aorta(No. 16a2, b1). Our clinical diagnosis was cT4a(SE)N+M1(PAN), cStage Ⅳb, and SOX therapy was immediately administered. After 3 courses of chemotherapy, the treatment effect was PR, and after 6 courses, the patient was diagnosed with ycT2(MP)N0M0, ycStageⅠB. No Grade 2 or higher adverse events were observed during chemotherapy. At this stage, we determined that radical resection was feasible; thus, distal gastrectomy and D3 dissection(para-aortic lymph node dissection)were performed. No cancer cells were found in the primary lesion on histopathology. The histological response of the primary lesion was Grade 3, and the lymph node was Grade 2b. On follow-up observation, the patient is alive without tumor recurrence at 1 year postoperatively.