[Chemotherapeutic Strategies for Peritoneal Dissemination of Gastric Cancer].

The prognosis of unresectable or metastatic gastric cancer is poor. One of the reasons for this is peritoneal dissemination, which is often observed in gastric cancer. Here, we discuss some new therapeutic strategies, especially chemotherapeutic strategies, for peritoneal dissemination of gastric cancer. Occasionally, in cases of peritoneal dissemination, patients have severe ascites or bowel obstruction. For those who have such complications, treatment via chemotherapy including S-1, capecitabine, or cisplatin is inappropriate. Therefore, methotrexate plus 5-fluorouracil(5-FU), 5-FU continuous infusion, 5- FU plus l-levofolinate, or paclitaxel are generally administered to such patients. To improve the efficacy of chemotherapy for such patients, an ongoing clinical trial(JCOG1108)is comparing triplet chemotherapy(FLTAX)including 5-FU plus l-levofolinate plus paclitaxel with chemotherapy including 5-FU plus l-levofolinate. For gastric cancer with positive lavage cytology, S-1 monotherapy or S-1 plus cisplatin therapy are often used. However, till date there has been no prospective clinical trial that has evaluated the efficacy of these therapies in gastric cancer with peritoneal dissemination. Therefore, further clinical trials are warranted to evaluate which chemotherapy is more suitable for patients with gastric cancer with peritoneal dissemination. Moreover, the use of conventional combination chemotherapy and intraperitoneal(IP)chemotherapy for patients with gastric cancer with peritoneal dissemination is now under evaluation. At the latest ASCOmeeting, the results of the "PHOENIX-GC trial" were reported. In this trial, patients receiving IP paclitaxel, intravenous(IV)paclitaxel, and S-1(experimental arm)and those receiving S-1 plus cisplatin(control arm)were compared. Longer survival was observed in the IP paclitaxel group compared with the other groups; however, this difference did not reach statistical significance. We hope that the evaluation of data from clinical trials would result in the identification of the optimal treatment strategy for patients with gastric cancer with peritoneal dissemination.