Lung cancer is the most common cancer worldwide and the most common cause of 
cancer-related death. Non-small-cell lung cancer comprises ~87% of newly 
diagnosed cases of lung cancer, and nearly one-third of these patients have 
stage III disease. Despite improvements in the treatment of stage IV lung 
cancer, particularly with the introduction and dissemination of checkpoint 
inhibitors, very little progress has been made in the treatment of stage III 
lung cancer. In this article, we discuss the general staging criteria and 
treatment options for stage III lung cancer. We review how concurrent radiation 
and chemotherapy can have immunomodulatory effects, supporting the rationale for 
incorporating immunotherapy into existing treatment paradigms. Finally, we 
discuss the results of the PACIFIC trial and implications for the treatment of 
stage III lung cancer. In the PACIFIC trial, adding durvalumab as a maintenance 
therapy following the completion of chemoradiotherapy improved progression-free 
survival in patients with locally advanced unresectable stage III lung cancer. 
On the strength of these results, durvalumab has been approved by the US Food 
and Drug Administration for use in this setting, representing the first advance 
in the treatment of stage III lung cancer in nearly a decade.