Extracellular Vesicles, Exosomes, and Cancer: Detection and Therapeutic Monitoring

Extracellular vesicles (EVs) are membrane-bound vesicles released by cells into the extracellular space. Exosomes are a nanoscale subtype of extracellular vesicles (typically 30–200 nm) secreted by almost all types of cells. They carry a diverse molecular cargo, including proteins, metabolites, lipids, RNAs, and glycoproteins, which closely reflect the physiological and pathological state of their cells of origin. Through this cargo, exosomes play critical roles in intercellular communication, immune regulation, and cellular signaling. In recent years, exosomes and extracellular vesicles have gained considerable attention as noninvasive biomarkers for disease monitoring, particularly in cancer, where tumor-derived exosomes exhibit distinct molecular signatures that enable early detection, diagnosis, and assessment of disease progression. Emerging applications include the use of exosomes and EVs to monitor responses to immunotherapy and chemotherapy, as well as their potential exploitation as therapeutic targets. Additionally, exosomes and EVs have been explored as vehicles for drug delivery and other therapeutic interventions. This review highlights the role of exosomes and EVs as cancer biomarkers, with an emphasis on their application in therapy monitoring. It further discusses recent advances involving exosomal glycoproteins, the relationship between exosomes and cancer stem cells, and the emerging significance of exosomal glycoRNAs in cancer detection and tumor development.