Takamori S, et al. – The discordance in the programmed cell death–ligand 1 (PD–L1) expression between primary and metastatic tumors was examined. Also, experts sought to investigate the association between the discordance and the clinical factors in non–small cell lung cancer (NSCLC) patients. Study outcomes suggested the involvement of radiotherapy–derived effects to the positive conversion of the primary PD–L1–negative NSCLC.