CEACAM5 and neoplasm: Circulating exosomes have higher levels of exosomal markers (CD63, CD81, and CD9) [11,12], a few tumor antigens (carcinoembryonic antigen [CEA], CA125) [13], and stemness markers (epithelial cell adhesion molecule [EpCAM], CD24) [14], all of which may be useful for diagnosis.