Cytoreduction and HIPEC for Gastric Carcinomatosis: Multi-institutional Analysis of Two Phase II Clinical Trials

Introduction: There are no approved locoregional therapies for peritoneal carcinomatosis from gastric adenocarcinoma (GA). Cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS–HIPEC) represents a potential treatment for advanced GA with isolated peritoneal metastasis. Patients and Methods: Two separate single-institution phase II, single-arm studies evaluating CRS–HIPEC using cisplatin with mitomycin C (NIH: NCT03092518, MDACC: NCT02891447) in patients with GA and confirmed peritoneal metastasis were analyzed. The primary endpoint of each trial was overall survival (OS). Clinical, pathologic, and treatment variables were analyzed for association with outcomes. Results: Over 4 years, 41 patients with peritoneal carcinomatosis from GA underwent CRS–HIPEC. All patients had synchronous peritoneal metastasis and received systemic chemotherapy as front-line therapy. A total of 23 patients also received laparoscopic HIPEC prior to open CRS–HIPEC. The majority (63%, n = 26) were male, and median PCI score at CRS–HIPEC was 2. Median OS was 24.9 months from diagnosis and 14.4 months from CRS–HIPEC. Three-year OS was 25% from diagnosis and 22% from CRS–HIPEC. Median RFS was 7.4 months. The rate of 30-day Clavien–Dindo grade ≥ 3 complications was 32%; specifically, the rate of anastomotic leak was 22%. Multivariable analysis identified the number of pathologically positive lymph nodes as an independent predictor of postoperative OS. Conclusions: In patients with gastric adenocarcinoma and isolated peritoneal metastasis treated with CRS–HIPEC, 3-year OS was 22% from CRS–HIPEC, and complications were common. The number of pathologic lymph node metastases was inversely correlated with overall survival. Further investigation of CRS–HIPEC for GA should include patient selection based on response to systemic chemotherapy or incorporate novel intraperitoneal treatment strategies.