Previous studies had reportedthe PTN is a tumour marker in NSCLC, with a sensitivity and specificity of 78.4% and 66.7% at cutoff value of 300.1 ng/mL.19 In the present study, the diagnostic value was 258.18 ng/mL and had a sensitivity and specificity of PTN to differentiate SCLC from BLD, SCLC and HV was 79.2%, 91.7%, 86.7% and 95.8%, respectively. The gene discussed is PTN; the disease is small cell lung carcinoma.