 This study identified a novel and powerful lipid metabolism-related gene, LMAGs, signature that can effectively evaluate the prognosis of gastric cancer, GC, patients and reflect the metabolic and immune status. Furthermore, this study found that SD6-GalNAC3 may be a potential prognostic marker to improve the survival rate and prognostic accuracy of GC patients, and may even be a potential biomarker of GC patients, indicating the response to immunotherapy.