[Palliative Radiotherapy and Sequential Nivolumab Administration for Recurrent Gastric Cancer-A Case Report].

A 52-year-old man underwent total gastrectomy for advanced gastric cancer. The postoperative diagnosis was por1>muc >por2>tub2, pT4a(SE)N3bM0H0P0CY0, pStage C. He underwent 6 courses of adjuvant chemotherapy with capecitabine plus oxaliplatin. Six months after the surgery, CT showed 2 recurrent lesions: a tumor behind the esophago-jejunal anastomosis and another in the mesentery around the jejuno-jejunal anastomosis. Endoscopy showed intrajejunal invasion. Second-line therapy with paclitaxel and ramucirumab were administered for 3 courses, resulting in rapid progression of the disease. Palliative radiotherapy(39.6 Gy/22 Fr)for both lesions was performed for local control. Sequential administration of nivolumab was started 9 days after terminating radiotherapy. After 6 courses, both tumors markedly reduced PR, and the oral intake of food improved. After 10 courses, there was hyper-progression of the tumor behind the esophago-jejunal anastomosis and shrinkage of the other tumor. Surgery (left upper abdominal exenteration and enucleation of the tumor in the mesentery)was performed to release the jejunal limb obstruction. The tumor behind the esophago-jejunal anastomosis was a poorly differentiated adenocarcinoma, and no viable cancer cells were seen in the tumor in the mesentery. Radiotherapy and immune checkpoint inhibitors may be effective for gastric cancers, although the mechanism of action should be elucidated.