Gastric cancer with peritoneal metastases: a single center outline and comparison of different surgical and intraperitoneal treatments

Introduction Gastric cancer with peritoneal metastasis (GCPM) has an unfavourable prognosis. Cytoreductive surgery plus hyperthermic intraperitoneal chemotherapy (CRS + HIPEC) and pressurized intraperitoneal aerosol chemotherapy (PIPAC) are promising treatment options that have been shown to improve survival. The aim of this study was to assess the impact of different treatments such as systemic chemotherapy, systemic chemotherapy + PIPAC, and CRS + HIPEC in patients with GCPM.Material and methods This single-centre retrospective study included 82 patients with GCPM treated between January 2016 and June 2021. After first-line chemotherapy, depending on disease response and burden, the patients were divided into three treatment groups: chemotherapy alone, chemotherapy + PIPAC, and CRS + HIPEC. The primary outcome was overall survival (OS) from diagnosis, which was compared among the treatment groups.Results Thirty-seven (45.1%) patients were administered systemic chemotherapy alone, 25 (30.4%) received chemotherapy + PIPAC, and 20 (24.4%) underwent CRS + HIPEC. The CRS + HIPEC group had better OS (median 24 months) than the PIPAC group (15 months, p = 0.01) and chemotherapy group (5 months, p = 0.0001). Following CRS + HIPEC, the postoperative grade 3-4 complication rate was 25%, and no postoperative in-hospital deaths occurred. The median disease-free survival (DFS) was 12 months. Multivariate analysis identified peritoneal carcinomatosis index (PCI) > 7 as an independent predictor of worse DFS. No independent predictors of OS were identified.Conclusion Among patients with GCPM, we identified a highly selected population with oligometastatic disease. In this group, CRS + HIPEC provided a significant survival advantage with an acceptable major complication rate compared with other available therapies (systemic chemotherapy alone or in combination with PIPAC).