Commercial microbeads conjugated with anti-CD9 antibodies along with quantum dots (QD) for carcinoembryonic antigen (CEA), fragments of cytokeratin 19 and pro-gastrin-releasing peptide (Pro-GRP) were used to identify and fluorescently label sEVs isolated from lung adenocarcinoma (A549), lung squamous carcinoma (H226), small cell lung cancer (H446), human umbilical vein endothelial (HUVEC) cells and plasma from 10 patients who had not undergone primary surgical resection of lung cancer and 10 healthy controls. Here, GRP is linked to lung cancer.