A Case of HER2-Positive Gastric Cancer with Multiple Liver Metastases Treated with Curative Conversion Therapy after Chemotherapy

A 66-year-old man underwent chemotherapy with S-1 plus cisplatin plus trastuzumab to treat advanced gastric cancer that was diagnosed as cStage Ⅳ adenocarcinoma(T3N1M1[P0, CYX, H1]). After 8 courses, liver metastases were absent on contrast-enhanced MRI. The patient underwent a laparoscopic distal gastrectomy with D2 lymphadenectomy. The gross appearance of the surgically resected specimen showed a shrunk gastric tumor measuring 1 mm. The postoperative course was uneventful, and the patient has been well, receiving maintenance chemotherapy of S-1 plus trastuzumab without evidence of recurrence for 15 months following the operation. Conversion surgery following chemotherapy might be an effective treatment for patients with advanced gastric cancer; however, further studies are needed to establish this treatment strategy.