A Phase 2 Study of Induction Chemotherapy Using Docetaxel, Cisplatin, and S-1 for Gastric Cancer with Peritoneal Metastasis (KUGC06).

Abstract

The authors previously showed the significant efficacy of S-1 plus cisplatin for gastric cancer with limited peritoneal metastasis. They conducted a phase 2 study to evaluate the safety and efficacy of induction chemotherapy using a docetaxel, cisplatin, and S-1 (DCS) triplet regimen to treat gastric cancer with peritoneal metastasis. The key eligibility criteria were gastric cancer with peritoneal metastasis or positive peritoneal cytology but no other distant metastases and capability of oral administration. The patients received three 28-day cycles of DCS (60 mg/m² of cisplatin, 40 mg/m² of docetaxel on day 1, and 80 mg/m² of S-1 from day 1 to day 14), then underwent D2 gastrectomy if R0 was possible. The primary end point was the R0 resection rate. The sample size was determined to have 80% power for detecting a 20% improvement in the R0 resection rate over a 45% baseline for a one-tailed alpha of 0.1. Among 30 enrolled patients, 24 completed three cycles of DCS. The most frequent grade 3 or 4 toxicity was neutropenia (60%). A complete response of peritoneal metastasis was observed in 16 patients, and 14 patients achieved R0 resection (47%; 95% confidence interval 28-66%). When the extent of peritoneal metastasis was classified as P0CY1, P1, P2, and P3 according to the Japanese classification, the R0 resection rates were respectively 63%, 60%, 46% and 0%. Induction chemotherapy with DCS is safe and can achieve R0 resection for some patients with limited peritoneal metastasis or positive peritoneal cytology. The efficacy, however, appears similar to that of S-1 plus cisplatin.