CEACAM5 and adenocarcinoma: By adding three conventional blood tumor markers (each with disappointing sensitivity or specificity for NSCLC diagnosis), the newly developed non-invasive diagnostic 4-molecule panel, consisting of exosomal miR-17 5p, CEA, CYFRA21–1 and SCCA, was suggested to have a considerable clinical value in the diagnosis of NSCLC, although not yet able to discriminate between adenocarcinoma (Ad) and squamous carcinoma (SCC).