Megestrol acetate versus dexamethasone to prevent nausea and vomiting in patients with gastric or gastro-oesophageal junction cancer treated with oxaliplatin-based chemotherapy: study protocol of a multicentre, randomised, non-inferiority trial

INTRODUCTION: Oxaliplatin is widely used in the treatment of gastric and gastro-oesophageal junction cancer. However, oxaliplatin-induced nausea and vomiting often complicate treatment and negatively affect patients' quality of life. The current standard antiemetic regimen-dexamethasone (DEX) plus palonosetron-offers only limited efficacy, benefiting approximately 70% of patients, and is associated with steroid-related adverse effects, including insomnia and gastrointestinal bleeding. Consequently, there is a clear clinical need for effective DEX-free antiemetic regimens. This study aims to evaluate the efficacy and safety of megestrol acetate versus DEX in preventing oxaliplatin-induced nausea and vomiting in patients with gastric or gastro-oesophageal junction cancer. METHOD AND ANALYSIS: This is an investigator-led, multicentre, randomised-controlled, open-label, phase III, non-inferiority trial. Chemotherapy-naïve patients scheduled to receive oxaliplatin-based chemotherapy are randomly (1:1) assigned to receive either megestrol acetate (megestrol acetate group) or DEX (DEX group) in combination with palonosetron. The primary endpoint is the complete response (CR; no vomiting and no rescue therapy) rate during the first 120 hours following the initiation of chemotherapy (0-120 hours). Secondary endpoints include the following indicators: CR rate in acute period (0-24 hours), CR rate in delayed period (24-120 hours), time to treatment failure, frequency of salvage medication use, nausea, anorexia, adverse events and quality of life.The study will evaluate the efficacy and safety of megestrol acetate compared with DEX for prevention of oxaliplatin-induced nausea and vomiting in patients with gastric or gastro-oesophageal junction cancer. If proven effective, the results might inform future antiemetic strategies in the long term to (1) provide a novel DEX-free antiemetic treatment for prevention of moderate-emetogenic chemotherapy, (2) reduce DEX-related adverse effects and improve quality of life in patients with gastric or gastro-oesophageal junction cancer and (3) support the potential incorporation of megestrol acetate into standard antiemetic medications. ETHICS AND DISSEMINATION: The study protocol is conducted in accordance with the Declaration of Helsinki and approved by the Certified Review Board of West China Hospital, Sichuan University (Ethics Approval No 1116/2023). The results of this study will be disseminated via presentations at national and international scientific conferences and publication in peer-reviewed journals. TRIAL REGISTRATION NUMBER: ChiCTR2300075943.