Group 1. Asymptomatic High Risk Subjects. Smokers aged >=18 undergoing chest CT

Group 2. Symptomatic High Risk Subjects Without a Tissue Diagnosis. This group will comprise patients who are undergoing medical evaluation for a pulmonary symptom such as chronic unexplained cough or hemoptysis.

Group 3. Symptomatic High Risk Subjects With a Tissue Diagnosis. This group will be found to include a. lung cancer, and b. diseases other than lung cancer e.g. sarcoidosis, COPD or pulmonary infection.

Group 4. Apparently healthy individuals having no signs and symptoms of lung carcinoma.

Group 1 - Asymptomatic High Risk Subjects

Inclusion criteria

1. Patient is willing and able to cooperate with study and give signed informed consent to participate.
2. Patient has had (or will have) chest imaging with spiral CT within 7 days of breath test.
3. Age at least 18 years.
4. History of at least 10 pack-years of cigarette smoking.
5. Provide written informed consent prior to admission into the study.

Exclusion criteria

1. Previously documented history of cancer of any site.

Group 2 - Symptomatic High Risk Subjects Without a Tissue Diagnosis

Inclusion criteria

1. Patient is willing and able to cooperate with study and give signed informed consent to participate.
2. Patient does not have a tissue diagnosis of pulmonary disease.
3. Patient is undergoing evaluation for an unexplained pulmonary illness which is clinically consistent with lung cancer. This includes patients with unexplained symptoms (e.g. chronic unexplained cough or hemoptysis), unexplained signs (e.g. weight loss, lymphadenopathy) or unexplained investigations (e.g. an abnormal chest x-ray).
4. Actively smoking patients, as well as never smokers and former smokers are eligible for the study so long as a complete smoking consumption history can be recorded.

Exclusion criteria

1. Previously documented history of cancer of any other site.

Group 3 - Symptomatic High Risk Subjects with a Tissue Diagnosis

Inclusion criteria

1. Patient is willing and able to cooperate with study and give signed informed consent to participate.

2. Patient has a tissue diagnosis of a. lung cancer. or b. pulmonary disease other than lung cancer e.g.

   sarcoidosis, COPD, or pulmonary infection.

3. A diagnosis of lung cancer is defined as cytologic or histologic confirmation of lung cancer by bronchoscopic/thoracoscopic means, sputum cytology, percutaneous fine needle aspiration biopsy. Patients may have either non-small cell lung cancer or small cell lung cancer.
4. Breath VOC collection will be obtained prior to any invasive procedure e.g. thoracotomy, mediastinoscopy or mediastinotomy.
5. Actively smoking patients, as well as never smokers and former smokers are eligible for the study so long as a complete smoking consumption history can be recorded.

Exclusion criteria

1. Previously documented history of cancer of any other site.

Group 4 - Apparently healthy subjects

Inclusion criteria

1. Willingness to follow protocol requirements as evidenced by written, informed consent.
2. Healthy, male or female subjects, ages 18 and older.
3. Subjects who are non smokers having no signs or symptoms of lung carcinoma

Exclusion Criteria

1. Any active ongoing medical problems.