The study goal is to collect blood samples from individuals at risk for lung cancer in order to identify protein markers for diagnosis of lung cancer in the Chinese population.

Inclusion Criteria:

• Adults ≥ 18 years of age
• Patients referred to pulmonologists, oncologists, or thoracic surgeons for diagnosis of suspicious pulmonary nodules as either lung cancer or benign and undergoing bronchoscopic biopsy
• Patients will be enrolled if the result of the bronchoscopic biopsy is a diagnosis of NSCLC or benign pulmonary nodule
• Cases: Patients with untreated non-small cell lung cancer, i.e. primary lung adenocarcinoma or squamous cell carcinoma of early
• Computed tomography or X-Ray is available and shows a suspicious pulmonary nodule
• A biopsy or surgical resection to clarify the nature of the lung nodule is available (NSCLC or benign, including histological diagnosis) in both groups
• Controls: Patients must be available for a 6 month follow-up to confirm benign diagnosis
• A serum and plasma sample was collected prior to any treatment of the lung nodule beyond biopsy
• No other cancer diagnosis in the last 5 years excluding non-melanoma skin cancer
• Patients must be fully informed of the investigational nature of the procedure and sign an informed consent.

Exclusion Criteria:

• Prior treatment for lung cancer by chemotherapy or surgery (excluding biopsy)
• Patients with benign nodules who are not able or willing to have a 6-month follow-up visit to confirm benign diagnosis
• Diagnosis or treatment of other cancer in the last 5 years excluding non-melanoma skin cancer. In the judgment of the clinical investigator, patients who are likely to be non compliant or uncooperative during the study.

A total of 300 patients will be recruited from hospital pulmonary clinics. The study participants will have pulmonary nodules suspicious for lung cancer and a bronchial biopsy diagnosis of NSCLC or probable benign. Approximately half of the patients will be cases and half controls.