The present study is a single arm clinical trial aiming to improve the key technology in the diagnosis and treatment of early stage lung cancer. 60,000 high-risk subjects (age 45-70) are planned to recruit and assign to the Low Dose Computed Tomography (LDCT) screening arm (Baseline + 2 rounds of biennial repeated LDCT screening). Management of positive screening test will be carried out by a pre-specified protocol.