A phase II study of induction chemotherapy with docetaxcel, cisplatin, and S-1 (DCS) for gastric cancer with peritoneal metastasis (KUGC06): Early results.

Abstract

e15574 Background: Although the prognosis of gastric cancer with peritoneal metastasis is extremely poor, we previously showed the significant efficacy of S-1 plus cisplatin for limited peritoneal dissemination, and favorable outcome following curative resection. We conducted a phase II study to evaluate the safety and efficacy of induction chemotherapy with docetaxel, cisplatin, and S-1 (DCS) triplet regimen for patients (pts) with gastric cancer with peritoneal metastasis. Methods: The key eligibility criteria were gastric cancer with peritoneal metastasis or positive peritoneal cytology, without any other distant metastases, age between 20 and 75 years old, PS 0 or 1, capable of oral administration, and adequate hematologic, hepatic, and renal function. Pts received three 28-day cycles of DCS (cisplatin of 60 mg/m2, docetaxel of 40mg/m2 on day 1, and S-1 of 80 mg/m2 from day 1 to 14). Following evaluation for resectability, pts received D2 gastrectomy if R0 was possible. Primary endpoint was R0 resection rate. Secondary endpoints were clinical response of peritoneal metastasis, overall response, pathological response, adverse events, progression free survival, and overall survival. Sample size was determined to have 80% power for detecting 20% improvement of R0 resection rate over 45% baseline at one-sided alpha of 0.1. Results: Between June 2011 and April 2015, 30 pts were enrolled. All pts started DCS and were included in the analysis. Three cycles of DCS (80%) were completed in 24 pts (80%). The most frequent grade 3/4 toxicity was neutropenia (60%). Complete response of peritoneal metastasis was observed in 16 pts (53%), 21 pts underwent surgery, and 14 pts achieved R0 resection (47%; 95%CI, 28-66%). When the extent of peritoneal metastasis was classified as P0CY1, P1, P2, and P3 according to the Japanese classification, R0 resection rate for each group was 63%, 60%, 46%, or 0%, respectively. Conclusions: Induction chemotherapy with DCS is safe, and could achieve R0 resection in some patients with limited peritoneal metastasis or positive peritoneal cytology. However, the efficacy seems to be similar to the conventional S-1 plus cisplatin. Clinical trial information: UMIN000004932.