Even so, these markers can be detected in some benign lesions, leading to high false‐negative/positive rates.37, 38 Most publications report that a combination of several tumor markers provides high sensitivity, but the most useful combination of such markers remains unclear.39, 40, 41 In our study, the combination of four tumor markers—CEA, CA 125, CYFRA 21‐1, and SCC—yielded had a lung cancer diagnostic sensitivity of 63.41%, which was lower than that achieved based on CTC counts alone. This evidence concerns the gene CEACAM5 and lung cancer.