Reviewing the overall existing literature of biomarkers for distinguishing NSCLC from benign pulmonary nodules, we may apply plasma miRNAs, ctDNA, circulating cancer cell (CTC), together with existing tumor biomarkers (such as CEA, NSE, Cyfra21-1) to the early diagnosis of lung cancer in clinic in the future. The gene discussed is CEACAM5; the disease is lung cancer.