Using RT-PCR, KS1/4 was previously reported to be the most sensitive marker among CEA, CK19, KS1/4, LunX, muc1 and PDEF for the detection of metastatic NSCLC in mediastinal lymph nodes, and LunX was with the second highest sensitivity distinguishing lung cancer from lung benign disease [6]. This evidence concerns the gene CEACAM5 and lung cancer.