Comparison of programmed death-ligand 1 protein expression between primary and metastatic lesions in patients with lung cancer ============================================================================================================================== * Myrto K Moutafi * Weiwei Tao * Richard Huang * James Haberberger * Brian Alexander * Shakti Ramkissoon * Jeffrey S Ross * Konstantinos Syrigos * Wei Wei * Lajos Pusztai * David L Rimm * Ioannis A Vathiotis