Abstract: Objective:To explore the clinical value of the levels of serum progastrin releasing peptide(proGRP) in the differential diagnosis and clinical staging of small cell lung cancer(SCLC) and non-small cell lung cancer(NSCLC).Methods:The serum levels of proGRP in 62 patients with SCLC(including 25 cases of limited stage and 37 cases of extensive stage) and 38 patients with NSCLC were measured by chemiluminescent immunoassay, which was compared with neuron specific enolase(NSE).The sensitivity, specificity and tumor staging in all patients were analyzed.Results:The sensitivities of the single detection of proGRP, NSE and combination detection of proGRP and NSE in diagnosing SCLC were 82.93%, 64.15% and 71.58%, respectively.The positive rate of the combination detection of proGRP and NSE in diagnosing SCLC was significantly higher than that of the single detection of NSE, the difference of the positive rate between combination detection proGRP and NSE and single detection of proGRP was not statistically significant(P>0.05).The serum levels of proGRP and NSE in patients with SCLC were obviously higher than those in NSCLC patients(P<0.01).Among the SCLC patients, the serum levels of proGRP and NSE in extensive stage patients were significantly higher than those in limited stage patients(P<0.01).Conclusions:The ProGRP is a tumor marker of SCLC, which is high sensitivity and specificity, and can reflect the staging.The combination detection of proGRP and NSE can improve the accurate rate of SCLC diganosis.