A Case of Advanced Gastric Cancer for Which Curative Resection Was Performed, Despite CEA Elevation

A 32-year-old man was admitted to our hospital with the complaint of epigastric pain. Gastrointestinal endoscopy revealed a type 5 advanced gastric cancer at the posterior wall of the antrum. Contrast-enhanced computed tomography (CT) and endoscopic ultrasonography showed a fluid collection, indicating peritoneal metastasis. CEA levels were elevated, at 16.5 ng/mL. A diagnosis was made of cStage Ⅳ (T4aN3H0P1M1), and he underwent first-line chemotherapy using CDDP and S-1. However, this immediately failed with the severe adverse effect of vomiting.Docetaxel and S-1 were adopted as second-line chemotherapy. Since progression of the disease was confirmed after 8 cycles of second-line chemotherapy, nab-paclitaxel was administered as third-line chemotherapy. Despite a trend of increasing CEA after 4 cycles of third-line chemotherapy, CT revealed a tumor volume reduction as well as the disappearance of the fluid collection, after which staging laparoscopy was performed. Based on the finding that non-curative factors such as fluid collection and peritoneal nodules were not observed, distal gastrectomy was performed. Histopathological examination showed a ypStage ⅠA (T1bN0H0P0M0)tumor with a grade 3 therapeutic response to chemotherapy.The patient is currently doing well with no recurrence 11 months after the operation.