Extracellular vesicle biomarkers in gastric cancer: Opportunities and challenges

Extracellular vesicles (EVs) are promising liquid biopsy candidates for gastric cancer because they can capture tumor-, immune-, microbial-, and microenvironment-related signals. We argue that the main challenge is no longer simply to find more candidates but to advance EV biomarkers with demonstrated diagnostic, therapeutic-monitoring, or prognostic value toward clinical translation. In this opinion article, we highlight EVs from nonblood biofluids, non-tumor-derived EVs, and underexplored EV cargo types, particularly small noncoding RNA cargoes, as sources of biomarker potential. We further identify insufficient clinical evidence, technical bottlenecks, and incomplete quality-control and regulatory standards as key barriers to their clinical deployment.