Gastrointestinal CancerEmerging treatment modalities for gastric cancer with peritoneal metastases: A systematic review

Introduction Gastric cancer remains associated with a high mortality, since patients often present with advanced-stage disease such as peritoneal metastases. Treatment options in this setting are limited and mainly consist of palliative systemic therapy. Objectives This systematic review aims to summarize emerging therapeutic strategies for patients with peritoneally metastasized gastric cancer in relation to response, toxicity, and survival. Methods A search was performed in PubMed, EMBASE, and Cochrane database until December 8, 2023. Studies were eligible if they prospectively investigated any form of cancer treatment in adult patients with peritoneally metastasized gastric cancer. Results In total, 25 articles were retrieved from 9 different countries, investigating systemic therapy, intraperitoneal therapy (IP), hyperthermic intraperitoneal chemotherapy (HIPEC) with or without cytoreductive surgery (CRS), and pressurized intraperitoneal aerosol chemotherapy (PIPAC). CRS-HIPEC followed by early postoperative intraperitoneal chemotherapy (EPIC) showed high complication rates and patient drop-out. Median overall survival (OS) ranged from 6.5 to 7.4 months with systemic chemotherapy, 13.0 to 23.9 months with IP chemotherapy, 6.8 to 13.0 months after PIPAC, 11.0 to 19.0 months with CRS-HIPEC, and 9.9 months in elderly with HIPEC alone. Notably, patients with a Peritoneal Cancer Index ≥20 showed median OS ≥13.0 months with IP chemotherapy or HIPEC without CRS. Conclusion Few prospective trials are conducted in patients with peritoneally metastasized gastric cancer. Although IP chemotherapy and CRS-HIPEC show encouraging results in selected cohorts, especially in Asia, current evidence from randomized studies is limited. Further prospective trials are needed to clarify their role alongside the current systemic therapy, including immunotherapy and targeted therapy.