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.

Inclusion Criteria:

- Never smokers who are admitted to the Seoul National University Hospital and newly diagnosed with lung cancer, with ECOG Performance Status 0 or 1

Exclusion Criteria:

• Patients who have received treatment for lung cancer before the enrollment
• Patients who have received treatment for OSA before the enrollment
• Patients with an expected life expectancy of less than 3 months
• Patients with neuromuscular disease, chronic opioid medication use, or severe insomnia not controlled by medication
• Patients receiving supplemental oxygen therapy due to underlying diseases including heart failure, chronic obstructive pulmonary disease, interstitial pulmonary disease, hypoventilation syndrome, stroke, or whose baseline oxygen saturation is less than 90%
• Patients with unstable medical conditions within the preceding 3 months (hospitalization due to acute exacerbation of underlying lung disease, diagnosis of unstable angina or myocardial infarction, history of percutaneous coronary intervention or coronary artery bypass surgery, or diagnosis of transient ischemic attack or stroke)
• Patients with an inability or unwillingness to provide informed consent

Inpatients in a tertiary referral hospital