[Unresectable Gastric Cancer Achieving pCR Via Conversion Surgery after Chemotherapy-Implications for Optimizing...

A patient was diagnosed with T4aN+ Stage Ⅲ gastric cancer. After 2 courses of SOX chemotherapy for initially unresectable disease. Additional pathological evaluation revealed tumor PD-L1 (22C3) CPS≥10, HER2 1+, Claudin18 negative status, and MSI negative. Consequently, 2 courses of SOX plus nivolumab were administered. Post-treatment CT revealed resectability, thus leading to robot-assisted distal gastrectomy with D2 lymph node dissection and Billroth-Ⅱ reconstruction was performed. Postoperative pathology showed no residual tumor cells in the primary lesion or lymph nodes, confirming a pCR (ypT0N0). The postoperative course was uneventful and there were no major complications. At 5 months postoperatively, no recurrence was detected and SOX chemotherapy is currently being administered as postoperative adjuvant therapy.