Lung cancer is the commonest malignant disease with a 5-year survival of 14%. In Hong Kong, it accounts for about 30% of all cancer death. The poor prognosis of lung cancer is due largely to the late clinical presentation of the disease. In order to improve the prognosis of lung cancer, an obvious approach is to develop sensitive methods for detecting lung cancer at much earlier stages when treatment is more likely to be curative.

However, the best way for identifying early lung cancer is still need to be determined. We hypothesis that by examining specimens that contain shed bronchial epithelial cells i.e. sputum, lung cancer can be sampled in its earliest possible phase. And by using autofluorescence bronchoscopy, a system specifically designed to detect early lung cancer/pre-invasive lesions, to identify the source of abnormal cells, we may able to detect eraly lung cancer and followed by curative treatment to improve the prognosis of this disease.

Inclusion Criteria:

• Current or ex-smokers who have smoked at least 20-pack-years (e.g. 1 pack per day for 20 years or more)
• Informed consent

Exclusion Criteria:

• Known malignant disease
• Unstable major medical disease
• Bleeding disorder
• Unwilling to have a bronchoscopy
• Women currently pregnant or nursing
• Known reaction to xylocaine, a local anaesthesia agent used for bronchoscopy