Conversion Surgery in Gastric Cancer Carcinomatosis

Background: After the REGATTA trial, patients with stage IV gastric cancer could only benefit from chemotherapy (CHT). However, some of these patients may respond extraordinarily to palliative chemotherapy, converting their disease to a radically operable stage. We present a single centre experience in treating peritoneal carcinomatosis from gastric cancer. Methods: All patients with stage IV gastric cancer with peritoneal metastases as a single metastatic site operated at a single centre between 2005 and 2020 were included. Cases were grouped according to the treatment received. Results: A total of 118 patients were considered, 46 were submitted to palliative gastrectomy (11 were considered M1 because of an unsuspected positive peritoneal cytology), and 20 were submitted to Hyperthermic Intraperitoneal Chemotherapy (HIPEC) because of a <6 Peritoneal Cancer Index (PCI). The median overall survival (OS) after surgery plus HIPEC was 46.7 (95% CI 15.8–64.0). Surgery (without HIPEC) after CHT presented a median OS 14.4 (8.2–26.8) and after upfront surgery 14.7 (10.9–21.1). Patients treated with upfront surgery and considered M1 only because of a positive cytology, had a median OS of 29.2 (25.2–29.2). The OS of patients treated with surgery plus HIPEC were 60.4 months (9.2–60.4) in completely regressed cancer after chemotherapy and 31.2 (15.8–64.0) in those partially regressed (p = 0.742). Conclusions: Conversion surgery for peritoneal carcinomatosis from gastric cancer was associated with long survival and it should always be taken into consideration in this group of patients.