Phase II study of weekly intravenous and intraperitoneal paclitaxel combined with S-1 for advanced gastric cancer with peritoneal metastasis

Background: A phase II study to evaluate the efficacy and tolerability of weekly i.v. and i.p. paclitaxel (PTX) combined with S-1 was carried out in gastric cancer patients with peritoneal metastasis. Patients and methods: Gastric cancer patients with peritoneal dissemination and/or cancer cells on peritoneal cytology were enrolled. PTX was administered i.v. at 50 mg/m 2 and i.p. at 20 mg/m 2 on days 1 and 8. S-1 was administered at 80 mg/m 2 /day for 14 consecutive days, followed by 7 days rest. The primary end point was the 1-year overall survival (OS) rate. Secondary end points were the response rate, efficacy against malignant ascites and safety. Results: Forty patients were enrolled, including 21 with primary tumors with peritoneal dissemination, 13 with peritoneal recurrence and six with positive peritoneal cytology only. The median number of courses was 7 (range 1― 23). The 1-year OS rate was 78% (95% confidence interval 65% to 90%). The overall response rate was 56% in 18 patients with target lesions. Malignant ascites disappeared or decreased in 13 of 21 (62%) patients. The frequent grade 3/4 toxic effects included neutropenia (38%), leukopenia (18%) and anemia (10%). Conclusion: Combination chemotherapy of i.v. and i.p. PTX with S-1 is well tolerated and active in gastric cancer patients with peritoneal metastasis.