Lung cancer is one of the most common cancer, there is a significant difference between the treatment and prognosis of small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). SCLC tumor cells usually express neuroendocrine tumor (NET) markers, among which there are many studies on chromogranin A (CgA), synaptophysin (Syn), neuronspecific enolase (NSE) and pro-gastrin-releasing peptide (Pro-GRP) with SCLC. The levels of CgA, NSE and pro-GRP were related to the stage of SCLC, which were significantly higher in patients with extensive stage than in patients with limited stage, and t...