It is aimed at investigating the changes of serum soluble programmed death-ligand 1 (sPD-L1) expression level in nonsmall cell lung cancer (NSCLC) before and after radiotherapy, the correlation of PD-L1, PD-1, and proteins of Akt (protein kinase B), mTOR, and HIF-1α, and the molecular mechanism of the PD-1/PD-L1 pathway in the development of NSCLS. The gene discussed is CD274; the disease is non-small cell lung carcinoma.