Several clinical tumor markers, such as carcinoembryonic antigen (CEA), cytokeratin 19 fragments (CYFRA 21-1), carbohydrate antigen 125 (CA-125), and carbohydrate antigen 19-9 (CA-199), have been shown to be valuable for the diagnosis of lung cancer and as predictors of survival in NSCLC patients [19, 20]. Here, CEACAM5 is linked to lung cancer.