Inclusion Criteria:  Subjects suspected or confirmed diagnosis of lung cancer. Subjects who had indeterminate sub-centimeter pulmonary nodules or ground glass opacities discovered by computed tomography. Non-cancer subjects: including healthy volunteers and chronic inflammatory airway diseases such as chronic obstructive airway disease, asthma, and bronchiectasis, etc. Subjects age over 20.  Exclusion Criteria:  Pregnancy. Subjects with HIV infection. Unable to or unwilling to give informed consent.