Of all the eight cdc6‐positive lung cancer patients who were in metastasis status, six were from small‐cell lung cancer and adenocarcinoma patients, which is in accordance with the consensus that adenocarcinoma and small‐cell lung cancer are apt to disseminate through blood stream, whereas squamous cell carcinoma easily disseminate through lymphatic system.26, 27 We also observed two subjects whose cdc6 was positive. This evidence concerns the gene CDC6 and squamous cell carcinoma.