Induction Chemotherapy with S-1 Plus Cisplatin Followed by Surgery for Treatment of Gastric Cancer with Peritoneal Dissemination

The prognosis of gastric cancer patients with peritoneal dissemination is poor. Recently, chemotherapy with S-1 plus cisplatin has been shown to be highly effective for advanced gastric cancer. In 41 patients diagnosed with either macro- or microscopic peritoneal dissemination by staging laparoscopy, and receiving induction chemotherapy with S-1 plus cisplatin between August 2002 and February 2008, response of peritoneal lesions to the induction chemotherapy and the outcome of the following surgery were retrospectively evaluated. Of 41 patients identified, 38 patients (93%) completed two cycles. Among grade 3 or 4 adverse effects, neutropenia was most frequently observed (9 patients; 22%). After chemotherapy, 32 patients (78%) underwent surgery and R0 resection was accomplished in 22 patients. Although objective response by Response Evaluation Criteria in Solid Tumors (RECIST) was recorded in only four patients (10%), peritoneal dissemination disappeared in 19 patients (46%). Patients with limited peritoneal metastasis, negative peritoneal cytology, or response of the primary lesion were more likely to exhibit disappearance of the peritoneal dissemination. Median survival time of all patients was 20.4 months. Patients with R0 resection had median survival time of 43.2 months, which was significantly longer than for those with noncurative resection (12.6 months) or without surgery (10.3 months). Limited peritoneal dissemination of gastric origin is highly sensitive to induction chemotherapy with S-1 plus cisplatin. Resection after disappearance of peritoneal metastasis could cure some patients.