Role of Bronchoscopy in Early Lung Cancer Screening of High Risk Population

Inclusion Criteria:

* Patient is over 40 years in age and is a heavy cigarette smoker.(smoking index is over 400)
* Patient has been coughing irritably for 2-3 weeks with a failed treatment and without obvious causes.
* The nature of cough changes in a patient who has chronic respiratory disease.
* Patient has blood-stained sputum persistently or repeatedly without obvious causes.

Patient will be included if accorded with any item of above.

Exclusion Criteria:

* Patient has dysrhythmia or cardiovascular disease that poses a risk during exercise.
* Patient has uncontrollable hypertension (SBP \> 180mmHg).
* Patient has severe organ dysfunction (shock, severe hepatic and renal dysfunction, massive hemorrhage of upper gastrointestine, diffuse intravascular coagulation(DIC) and massive hemoptysis,etc).
* Patient has blood coagulation disorders (PT\>2 times the upper limit of normal(ULN) or Platelet(PLT)\<50000/ul）.
* Patient has severe dyspnea.
* Patient is allergic to local anesthetic.
* Patient is unable to provide informed consent.
* Patient is not an appropriate candidate for or is unable to tolerate flexible bronchoscopy procedures.
* Patient has any disease or condition that interferes with completion of initial or follow-up assessments of the effectiveness endpoints.
* Patient has demonstrated unwillingness or inability to complete screening or baseline data collection procedures.
* Patient participated in a study of an investigational drug or device within the past 30 days prior to participation in this study, or is currently participating in another clinical study.
* Patient has pulmonary lesions suspected to be cancer from CT images.
* Female patient of childbearing potential has a positive result from a pregnancy test.