A Case in Which S-1/Oxaliplatin(SOX)/Trastuzumab Therapy Was Effective for Unresectable HER2 Positive Advanced Gastric Cancer and Radical Resection Could Be Performed

The case was a 70s-year-old man. In July 2016, he was admitted to our hospital with a complaint of epigastralgia. Upper gastrointestinal endoscopy revealed type 3 advanced gastric cancer in the vestibule, directly infiltrating the pancreas and the left lobe of the liver to form an abscess, and swelling of the aortic lymph node and multiple liver metastases were observed. The cancer was diagnosed as cT4b(liver/pancreas), N2M1(H1P0CYX), cStage IV and diagnosed it as a chemotherapy policy. We initiated SOX plus trastuzumab therapy from August 2016. After 4 courses, the primary tumor shrunk significantly and invasion to the pancreas/liver had disappeared. Furthermore, the periarterial lymph node and multiple liver metastases were obscured(chemotherapy effect judgment: PR). With a diagnosis of ycT4aN1MX(HXP0CYX), in December 2016, we performed a pyloric side gastrectomy D2(+No.16)dissection and partial resection of the liver(S3, S4, S6), liver RFA(S4, S6, S7). Due to recent progress in chemotherapy and multidisciplinary therapy, there is a possibility that radical resection may be carried out for advanced gastric cancer, which was previously unresectable, by performing a treatment with surgery in mind.