Our results confirmed that CYFRA21-1 and CEA were the most sensitive as a single marker in the diagnosis of NSCLC, while NSE was the best suited, followed by CEA, for the diagnosis of SCLC, which is in accordance with previous reports [14, 18, 19] (Molina, Agusti et al. 1994, Vinolas, Molina et al. 1998, Liu, Teng et al. 2017). The gene discussed is CEACAM5; the disease is small cell lung carcinoma.