[Gastric cancer with liver metastasis and peritoneal dissemination treated with conversion surgery to achieve r0 resection after capecitabine, cisplatin, and trastuzumab chemotherapy-a case report].

Herein, we present a case report suggesting the importance of conversion surgery and the effectiveness of adjuvant chemotherapy with trastuzumab. A 77-year-old woman was diagnosed with gastric cancer complicated by multiple liver metastases and peritoneal dissemination. Owing to a HER2 immunohistochemistry (IHC) tumor score of 3+, we initiated capecitabine plus cisplatin (CDDP) plus trastuzumab chemotherapy. Subsequently, the liver metastases and peritoneal dissemination were absent on computed tomography images, and no new metastatic lesions developed during chemotherapy. After 10 chemotherapy courses, the patient underwent distal gastrectomy and 2 partial liver resection procedures. The liver metastasis remained, and it received a score of 2+ on the HER2 IHC test. We have continued to administer postoperative capecitabine plus trastuzumab chemotherapy because no metastatic lesions have appeared.