CEACAM5 and lung cancer: It is noteworthy that among the patients with suspected lung cancer (upper lobe, subsolid and ≥ 8-mm nodules), the combination of CTC count with CEA level resulted in a distinct improvement in the diagnosis of NSCLC in terms of the sensitivity and specificity; the AUC was 0.73, and the 95% CI was 0.566–0.90.