[A case of HER2-positive advanced gastric cancer successfully treated with a combination of capecitabine, cisplatin, and trastuzumab as first-line chemotherapy].

We report a case of human epidermal growth factor receptor(HER)2-positive advanced gastric cancer successfully treated with a combination of capecitabine, cisplatin(CDDP), and trastuzumab as first-line chemotherapy. A 66-year-old woman diagnosed as having advanced gastric cancer underwent chemotherapy after abdominal computed tomography (CT)revealed multiple metastases to the liver, lung, lymph nodes, and peritoneum. Histopathological examination indicated a type 3, tub1, cT3(SS), N3, H1, P1, M1(LYM, PUL), cStage IV gastric tumor. Because overexpression of HER2 protein was observed in primary tumor immunostaining, combination therapy of capecitabine+CDDP+trastuzumab was administered as first-line chemotherapy. After 4 courses, CT scans revealed decreased primary tumor size, liver lesion, lymph nodes, and elimination of the lung lesion, thereby suggesting a partial response(PR). The grade 3 adverse events were neutropenia, anemia, and anorexia. After discontinuation of CDDP because of elevation of serum creatinine levels, combination therapy with capecitabine and trastuzumab was continued.