Extracellular Vesicles in Cancer: Mechanistic Insights and Clinical Applications

Extracellular vesicles (EVs) have emerged as important messengers in cell-to-cell communication, carrying biologically active molecules such as lipids, nucleic acids, and proteins that influence both normal physiology and disease. In cancer, EVs play complex and context-dependent roles, contributing to tumor growth, angiogenesis, immune evasion, metastasis, and resistance to therapy, while in certain settings, they may also support antitumor immune responses. Increasing evidence shows that EVs released from tumor and stromal cells actively reshape the tumor microenvironment (TME) and participate in the formation of pre-metastatic niches, thereby facilitating cancer dissemination. Because EVs are stable, readily detectable in body fluids, and reflect the molecular characteristics of their cells of origin, they have attracted considerable interest as minimally invasive biomarkers for cancer diagnosis, prognosis, and treatment monitoring. In addition, their natural biocompatibility makes them attractive candidates for targeted drug delivery. This review summarizes current knowledge on EV biogenesis, cargo composition, and functional roles in cancer progression, with a particular focus on recent advances in their clinical applications. Key challenges related to EV isolation, characterization, and clinical translations are also discussed, highlighting future opportunities for integrating EV-based strategies into precision oncology.