[Clinical significance and practice points of conversion therapy for gastric cancer with peritoneal metastasis]

Gastric cancer with peritoneal dissemination is usually considered to be oncologically unresectable and is known to have a very poor prognosis. Despite recent advances in systemic chemotherapy, peritoneal dissemination due to advanced gastric cancer (AGC) still remains the most life-threatening type of metastasis and recurrence, which usually causes ascites accumulation, intestinal obstruction, or hydronephrosis, and then seriously impairs the quality of life. In general, the median survival time of these cases is reported to be just only 6-9 months. Recently, conversion therapy for gastric cancer with peritoneal dissemination has been highly concerned. It is defined as a conversion surgery aiming at an R0 resection after chemotherapy for both primary gastric cancer and distant metastatic cancerous foci including peritoneal dissemination, which were originally unresectable due to technical and/or oncological reasons. In numerous clinical practices, the results of neoadjuvant intraperitoneal and systemic chemotherapy (NIPS) have been reported to be more satisfactory in comparison with traditional systemic chemotherapy alone. Some clinical trials have demonstrated the clinical efficacy of intravenous and intraperitoneal administration of paclitaxel (PTX) combined with oral S-1 for peritoneal dissemination of gastric cancer with or without malignant ascites. Particularly, a longer period of survival can be expected when conversion R0 gastrectomy is successfully performed after observing significant responses of NIPS. Some clinical practice key points of conversion therapy for AGC patients with peritoneal dissemination are reviewed, including the importance of intraperitoneal and systemic synchronous chemotherapy, the reasonable choice of intraperitoneal chemotherapy drugs, the evaluation of primary gastric cancer and metastatic foci before and after conversion therapy, some special complications of NIPS, the indications of conversion surgery and the adjuvant therapy after conversion surgery, ect.