Lung cancers have the worst incident and mortality rates. Cancers such as advanced non-small-cell lung carcinomas are inoperable and often the only treatment available is chemo-radiotherapy. There has been little improvement in long-term survival recently, prompting research into novel treatments. Immune checkpoint inhibitors (ICIs) are a form of immunotherapy used in lung cancer. The efficacy of ICIs is dependent on: the part of the pathway affected; the presence of prognostic biomarkers; the method of efficacy assessment; the stage of the disease and other drugs involved. Monoclonal antibodies, Toll-like receptor agonists and cancer vaccines have shown modest effects on survival. Refinement of treatment regimens and prognostic biomarkers will help improve the survival of patients in the future.