Pilot study of intraperitoneal administration of paclitaxel and oral S-1 for patients with peritoneal metastasis due to advanced gastric cancer

Background There is no standard treatment for peritoneal dissemination from gastric cancer. A novel combination chemotherapy has been introduced for patients with advanced gastric cancer with peritoneal metastasis. Methods This pilot study was performed on four patients to confirm safety and efficacy. They were diagnosed with unresectable gastric cancer with severe peritoneal dissemination by staging laparoscopy, or with metastasis to the transverse colon. We selected combined chemotherapy with both paclitaxel and S-1. Paclitaxel at 60 mg/m 2 or 60 mg/body was administered intraperitoneally on days 1 and 8 and S-1, at 80–120 mg/body, was administered orally for 14 days followed by 7 days’ rest, as one course. After five courses of this therapy, the primary gastric tumors were evaluated by conventional examinations, and second-look laparoscopy was performed to assess the efficacy of the treatment against the peritoneal metastases. Results After five courses, primary tumor reductions were confirmed, and no cancer cells were detected on pathocytological investigation during second-look laparoscopy in any of the patients. Three patients underwent total gastrectomy with lymph node dissection and one underwent left upper abdominal evisceration. Final histological staging showed two stage 3 and two stage 4 patients. The intraperitoneal administration of paclitaxel and the oral administration of S-1 were well tolerated. Three patients died, at 8, 15, and 29 months, respectively, after the initial treatment, and one has been alive for 54 months without recurrence. Conclusion This chemotherapy can be used in the treatment of patients with peritoneal metastasis of gastric cancer.