A Phase 2 Trial of Intravenous and Intraperitoneal Paclitaxel Combined with S-1 for Treatment of Gastric Cancer with Macroscopic Peritoneal Metastasis

Background: The prognosis of patients with gastric cancer with peritoneal metastasis is extremely poor. This phase 2 study evaluated the benefits and tolerability of weekly intravenous and intraperitoneal paclitaxel (PTX) treatment combined with oral S-1 in patients with gastric cancer who had macroscopic peritoneal metastasis.

Methods: Patients with gastric cancer who had primary tumors with macroscopic peritoneal metastasis were enrolled. PTX was administered intravenously at 50 mg/m2 and intraperitoneally at 20 mg/m2 on days 1 and 8, respectively. S-1 was administered at 80 mg/m2 per day for 14 consecutive days, followed by 7 days of rest. The primary endpoint was the 1-year overall survival (OS) rate. The secondary endpoints were the response rate, efficacy against malignant ascites, and safety.

Results: Thirty-five patients were enrolled. The median number of treatment courses was 11 (range, 2-35). The 1-year OS rate was 77.1% (95% confidence interval, 60.5-88.1). The overall response rate was 71% in 7 patients with target lesions. Malignant ascites disappeared or decreased in 15 of 22 (68%) patients. The frequent grade 3/4 toxic effects were neutropenia (34%), leukopenia (23%), and anemia (9%).

Conclusions: Combination chemotherapy consisting of intravenous and intraperitoneal PTX with S-1 is well-tolerated and effective in patients with gastric cancer who have macroscopic peritoneal metastasis.