Previous studies have yielded inconsistent findings regarding the association between obstructive sleep apnea and the prevalence and mortality of lung cancer. Smoking history, a common risk factor for lung cancer, chronic obstructive pulmonary disease, and obstructive sleep apnea, may act as a confounding variable, limiting interpretation of the results. The aim of this study is to evaluate the prevalence of obstructive sleep apnea in never smokers with lung cancer and to determine the effect of obstructive sleep apnea on the prognosis of lung cancer. Enrolled patients will undergo respiratory polygraphy before beginning treatment for lung cancer. This prospective cohort includes both cross sectional and longitudinal analyses.