A randomized phase II multicenter trial to explore efficacy of weekly intraperitoneal in comparison with intravenous paclitaxel administered immediately after gastrectomy to the patients with high risk of peritoneal recurrence: final results of the INPACT trial.

BACKGROUND Intraperitoneal administration of paclitaxel had been considered a promising option to treat peritoneal metastasis, the most frequent pattern of recurrence in gastric cancer after D2 gastrectomy, but its safety and efficacy after gastrectomy had not been fully explored. METHODS A phase II randomized comparison of postoperative intraperitoneal (IP) vs. intravenous (IV) paclitaxel was conducted. Patients with resectable gastric linitis plastica, cancer with minimal amount of peritoneal deposits (P1), or cancer positive for the peritoneal washing cytology (CY1) were eligible. After intraoperative confirmation of the above disease status and of resectability, patients were randomized to be treated either by the IP therapy (paclitaxel 60 mg/m2 delivered intraperitoneally on days 0, 14, 21, 28, 42, 49, and 56) or the IV therapy (80 mg/m2 administered intravenously using the identical schedule) before receiving further treatments with evidence-based systemic chemotherapy. The primary endpoint was 2-year survival rate. RESULTS Of the 86 patients who were randomized intraoperatively, 83 who actually started the protocol treatment were eligible for analysis (n = 39, IP group; n = 44, IV group). The 2-year survival rate of the IP and IV groups was 64.1% (95% CI 47.9-76.9) and 72.3% (95% CI 56.3-83.2%), respectively (p = 0.5731). The IP treatment did not confer significant overall or progression-free survival benefits, and was associated with particularly poor performance in patients with residual disease, including the CY1 P0 population. CONCLUSIONS We were unable to prove superiority of the IP paclitaxel over IV paclitaxel delivered after surgery to control advanced gastric cancer with high risk of peritoneal recurrence.