Cytoreductive Surgery With or Without Hyperthermic Intraperitoneal Chemotherapy for Gastric Cancer With Peritoneal Metastases (CYTO-CHIP study): A Propensity Score Analysis

PURPOSE Gastric cancer (GC) with peritoneal metastases (PMs) is a poor prognostic evolution. Cytoreductive surgery (CRS) yields promising results, but the impact of hyperthermic intraperitoneal chemotherapy (HIPEC) remains controversial. Here we aimed to compare outcomes between CRS-HIPEC versus CRS alone (CRSa) among patients with PMs from GC. PATIENTS AND METHODS From prospective databases, we identified 277 patients with PMs from GC who were treated with complete CRS with curative intent (no residual nodules > 2.5 mm) at 19 French centers from 1989 to 2014. Of these patients, 180 underwent CRS-HIPEC and 97 CRSa. Tumor burden was assessed using the peritoneal cancer index. A Cox proportional hazards regression model with inverse probability of treatment weighting (IPTW) based on propensity score was used to assess the effect of HIPEC and account for confounding factors. RESULTS After IPTW adjustment, the groups were similar, except that median peritoneal cancer index remained higher in the CRS-HIPEC group (6 v 2; P = .003). CRS-HIPEC improved overall survival (OS) in both crude and IPTW models. Upon IPTW analysis, in CRS-HIPEC and CRSa groups, median OS was 18.8 versus 12.1 months, 3- and 5-year OS rates were 26.21% and 19.87% versus 10.82% and 6.43% (adjusted hazard ratio, 0.60; 95% CI, 0.42 to 0.86; P = .005), and 3- and 5-year recurrence-free survival rates were 20.40% and 17.05% versus 5.87% and 3.76% ( P = .001), respectively; the groups did not differ regarding 90-day mortality (7.4% v 10.1%, respectively; P = .820) or major complication rate (53.7% v 55.3%, respectively; P = .496). CONCLUSION Compared with CRSa, CRS-HIPEC improved OS and recurrence-free survival, without additional morbidity or mortality. When complete CRS is possible, CRS-HIPEC may be considered a valuable therapy for strictly selected patients with limited PMs from GC.