A Case of Giant Gastric Neuroendocrine Carcinoma Which Was Became Resectable Due to Disappearance of Liver Metastasis after Chemotherapy

The patient is a 63-year-old man. CT scan revealed a giant mass in the stomach and about 1 cm single mass in the liver. He was diagnosed with gastric cancer with liver metastasis. After 6 courses of nivolumab+SOX therapy, CT scan showed disappearance of the liver metastasis and shrinkage of the primary lesion and surrounding lymph nodes. After more 4 courses, CT scan revealed continued disappearance of the liver metastasis, but the primary lesion grew larger, so distal gastrectomy was performed. Histopathological examination revealed neuroendocrine carcinoma(NEC). We report a case of giant gastric NEC in which the liver metastasis disappeared after chemotherapy and conversion surgery became possible.