Conversion Surgery Following Combination Treatment With Immune Checkpoint Inhibitors and Chemotherapy for Initially Unresectable Gastric Cancer

AIM: Conversion surgery (CS) for unresectable advanced gastric cancer (GC; clinical stage IVb) has increased in recent years owing to advances in drug therapy. However, little is known about CS following combination treatment with immune checkpoint inhibitors (ICIs) and chemotherapy. METHODS: We conducted a retrospective cohort study of patients initially unresectable metastatic GC. We treated 36 patients with initially unresectable metastatic GC. Thirty-four patients received combination treatment with ICIs and chemotherapy, 11 of whom underwent CS. We evaluated their short-term and long-term surgical outcomes. RESULTS: Among patients who underwent CS, six were male and five female, and the median (interquartile range) age was 71 (47-75) years. All patients started first-line therapy with S-1 plus oxaliplatin combined with nivolumab, and two patients underwent surgery after second-line treatment with ramucirumab and nanoparticle albumin-bound paclitaxel. There were four open, two laparoscopic, and five robotic surgeries. The median operative time was 348 (321-354) minutes, blood loss was 16 (10-30) mL, and number of retrieved lymph nodes was 38 (27-44); there were no cases of conversion to laparotomy. R0 resection was achieved in all patients. And postoperative pathology was complete response; three patients, ypStage I; four patients, II; three patient, III; zero patient IV; one patient. ICI and chemotherapy efficacy was Grade 1 in four patients, Grade 2 in two patients, and Grade 3 in five patients. Overall 2-year survival was 90.0% for those who underwent CS. CONCLUSION: CS following combination treatment with ICI and chemotherapy may be promising for initially unresectable metastatic GC.