A Case of Conversion Surgery after Nivolumab and Chemotherapy for Metastatic Gastric Cancer

We report a case of conversion surgery after nivolumab treatment and chemotherapy for metastatic gastric cancer. An 81-year-old man was diagnosed with advanced gastric cancer with enlarged para-aortic lymph nodes and FDG uptake on positron emission tomography. The patient was diagnosed with unresectable gastric cancer and received nivolumab and SOX therapy. After 7 courses of chemotherapy, the primary lesion disappeared with scarring and the para-aortic lymph nodes were reduced. Consequently, we performed a radical gastrectomy with D2 and para-aortic lymph node dissection as a conversion surgery. Histopathological results revealed a complete pathological response in both the primary lesion and lymph nodes, including the para-aortic lymph nodes. The patient did not receive any postoperative adjuvant chemotherapy and has been recurrence-free for 8 months.