Surgery after intraperitoneal and systemic chemotherapy for gastric cancer with peritoneal metastasis or positive peritoneal cytology findings.

BACKGROUND: Despite recent progress in systemic chemotherapy, the prognosis of gastric cancer patients with peritoneal metastasis (P1) or positive peritoneal cytology findings (CY1) is still poor. We developed a regimen combining intraperitoneal (IP) paclitaxel (PTX) with S-1 and PTX, which can produce notable efficacy with regard to peritoneal lesions. Surgery after response to combination chemotherapy is a promising option for P1 or CY1 gastric cancer. A retrospective study was performed to evaluate the safety and efficacy. METHODS: This study enrolled 100 primary P1 or CY1 gastric cancer patients treated with IP PTX plus S-1 and PTX at the University of Tokyo Hospital between 2005 and 2011. Radical gastrectomy was performed when peritoneal cytology findings became negative, and the disappearance or obvious shrinkage of peritoneal metastasis was confirmed by laparoscopy. The same chemotherapy regimen was restarted after surgery and repeated with appropriate dose reduction. RESULTS: Gastrectomy was performed in 64 (P1 56, P0CY1 8) of 100 (P1 90, P0CY1 10) patients. R0 resection was achieved in 44 patients (69%). The median survival time was 30.5 months [95% confidence interval (CI) 23.6-37.7 months] from the initiation of intraperitoneal chemotherapy and 34.6 months (95% CI 26.8-39.4 months) from the diagnosis of gastric cancer. Postoperative complications included anastomotic leakage and pancreatic fistula, each in two patients, which were cured conservatively. There were no treatment-related deaths. The median survival time of the 36 patients who did not undergo surgery was 14.3 months (95% CI 10.0-17.8 months). CONCLUSIONS: Surgery after response to intraperitoneal and systemic chemotherapy is safe and may prolong the survival of P1 and CY1 gastric cancer patients.