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

4542 Background: A phase II study to evaluate the efficacy and tolerability of weekly intravenous and intraperitoneal paclitaxel combined with S-1 was performed in gastric cancer patients with peritoneal metastasis. METHODS Gastric cancer patients with peritoneal dissemination and/or cancer cells on peritoneal cytology were enrolled. Paclitaxel was administered intravenously at 50 mg/m2 and intraperitoneally at 20 mg/m2 on days 1 and 8. S-1 was administered at 80 mg/m2/day for 14 consecutive days, followed by 7 days rest. The primary endpoint was the 1-year overall survival rate. Secondary endpoints were the response rate, efficacy against malignant ascites and safety. RESULTS Forty patients were enrolled, including 21 with primary tumors with peritoneal dissemination confirmed by staging laparoscopy, 13 with peritoneal recurrence, and 6 with positive peritoneal cytology only. The median number of courses administered was 7 (range 1-23). The 1-year overall survival rate was 78% (95% CI, 65-90%). The overall response rate was 56% (95% CI, 32-79%) in 18 patients with target lesions. Malignant ascites disappeared or decreased in 13 of 21 (62%) patients. The incidences of grade 3/4 hematological and non- hematological toxicities were 40% and 15%, respectively. The frequent grade 3/4 toxicities included neutropenia (38%), leukopenia (18%), anemia (10%), and nausea (8%). Catheter obstruction observed in one patient was the only complication related to the peritoneal access device or intraperitoneal infusion. There were no treatment-related deaths. CONCLUSIONS Combination chemotherapy of intravenous and intraperitoneal paclitaxel with S-1 is well tolerated and active in gastric cancer patients with peritoneal metastasis. No significant financial relationships to disclose.