Extended total gastrectomy after nivolumab for unresectable multivisceral invasive gastric cancer.

Background: Chemotherapy has been considered the main treatment for stage IV gastric cancer (GC). However, advances in chemotherapy have provided new clinical approaches, permitting conversion surgery with the aim of R0 resection after resolving unresectability issues.

Case Presentation: A 70-year-old man with gastric cancer invading the pancreatic tail and spleen and with periaortic lymph-node enlargement was admitted to our hospital. After 24 courses of nivolumab as third-line chemotherapy, periaortic lymph-node enlargement was resolved, and conversion surgery was planned. Intraoperatively, we found no peritoneal metastasis, but the distal pancreas, splenic hilum, and transverse colon were adhered to the gastric body. Therefore, we performed D2 total gastrectomy with distal pancreatosplenectomy and partial transverse colectomy. The pathological diagnosis was type III moderately differentiated tubular adenocarcinoma (tub2) with signet ring cells, stage ypT1b (SM), ly0, and v0. The pathological proximal and distal tumor margins were negative. One lymph-node metastasis was observed (No. 4d; 1/23). Postoperatively, no recurrence was observed over 7 months, without adjuvant chemotherapy.

Conclusions: Nivolumab may allow R0 resection in patients with unresectable gastric cancer. Conversion surgery should be considered even after third-line nivolumab treatment.