Lung cancer is the most prevalent cause of cancer and cancer-related deaths in the world, accounting for 13% of new cancer diagnoses each year, and is the leading cause of cancer-related deaths in both men and women, accounting for 29% of all cancer patient deaths. the 3rd National Cause of Death Survey Main Situation Study released by the Chinese Ministry of Health in 2008 showed that the incidence of lung cancer has increased by 465% over the past 30 years, and from the top 10 urban and rural In terms of the top 10 malignant tumor composition, lung cancer has replaced liver cancer as the first cause of death from malignant tumors in China (accounting for 22.7% of all deaths from malignant tumors). The survival time of lung cancer is strongly related to the stage of the disease at the time of diagnosis and the size of the tumor. The 5-year survival rate for early-stage lung cancer is 49%, while the 5-year survival rate for late-stage lung cancer drops to 2%. However, currently, only 16% of lung cancer patients are diagnosed at an early stage and very few patients are diagnosed at stage 0, resulting in an overall 5-year survival rate of only 15% for lung cancer . Autofluorescence bronchoscopy: It is a new type of bronchoscopy developed by using cellular autofluorescence and computer image analysis technology, which can significantly improve the sensitivity of bronchoscopy for early localization and diagnosis of lung cancer and its precancerous lesions. The technical principle is that under the irradiation of blue light, heterogeneous hyperplasia and micro-infiltrating carcinoma of bronchial epithelium will produce slightly weaker red fluorescence and weaker green fluorescence than normal tissues, making the lesion area reddish brown and the normal area green. Multicenter and randomized controlled studies have demonstrated the usefulness of autofluorescence bronchoscopy for the detection of carcinoma in situ. Therefore, given the high sensitivity of autofluorescence bronchoscopy in detecting precancerous lesions, AFB may be performed as a screening tool for people at high risk for lung cancer, especially central lung cancer.