Screening for Early Lung Cancer in Shanghai, China

Inclusion Criteria: * Age of 55 to 74 years; smoking history of at least 30 pack-years; and if former smoker, have quit within 15 years * Age 50 or older ,20 or more pack-year history of smoking, and one additional risk factor (occupational exposure, residential radon exposure, cancer history, family history of lung cancer, history of lung disease) * Age 35 and one additional risk factor * Ability to accept LDCT examination and sign informed consent form Exclusion Criteria: * Individuals with any symptoms suggestive of lung cancer （e.g., vigorous coughing, chest pain, weight loss, blood-stained sputum） * Individuals with acute pulmonary abnormalities or those in poor health conditions or those have metallic implants or devices in the chest or back will be excluded due to the potential impact on the results as well as difficulty of acquiring the images. * Pregnant women