Brocco D, Lanuti P, Simeone P, et al. - An observational prospective study was conducted, in order to shed light on the role of tumor-derived extracellular vesicles (EVs), both as diagnostic and prognostic markers in cancer individuals. A recently created and simplified flow cytometry method for circulating EV enumeration, subtyping, and isolation from a large cohort of metastatic and locally advanced non-hematological cancer individuals (N = 106) was applied. Results showed that in cancer individuals vs healthy volunteers as formerly published, EV counts were significantly higher. Moreover, when contrasted with healthy people, cancer individuals presented higher concentrations of circulating CD31+ endothelial-derived and tumor cancer stem cell-derived CD133 + CD326- EVs. Besides, an important association with poor overall survival was exhibited by higher levels of CD133 + CD326− EVs. Also, between circulating EVs in cancer individuals vs healthy controls, differences in terms of protein content and function were shown by proteomics analysis of EV cargoes. In conclusion, data firmly imply that blood circulating cancer stem cell-derived EVs may have a purpose as a diagnostic and prognostic biomarker in cancer.