ObjectiveTo systematically review the role and potential clinical value of nicotinamide N-methyltransferase (NNMT) in gastric cancer, aiming to provide new insights for diagnosis, treatment, and prognosis. MethodsRelevant literature from recent years on the involvement of NNMT in gastric cancer was thoroughly analyzed. The review focuses on the mechanisms by which NNMT influences cell proliferation, invasion, migration, and metabolic reprogramming in gastric cancer. Additionally, the study explores the potential of NNMT as a diagnostic and therapeutic target. ResultsNNMT was significantly overexpressed in gastric cancer tissues and was closely associated with tumor progression. It promoted malignant behaviors through various pathways, including metabolic regulation, enhancement of cancer cell proliferation and invasion, and alteration of the tumor microenvironment. Furthermore, NNMT played a crucial role in modulating host immune responses, which might impact the clinical prognosis of gastric cancer patients. ConclusionsNNMT exhibits significant biological functions in the development and progression of gastric cancer. As a potential biomarker and therapeutic target, it holds promising clinical value in the diagnosis and targeted treatment of gastric cancer, providing new strategies and evidence for precision therapy and prognosis assessment.