Risk status was divided into 3 groups: (1) High-risk group: age 55-74 years, history of smoking ≥30 pack-years, history of quitting <15 years (category 1); or age ≥50 years, history of smoking ≥20 pack-years, with additional risk factors other than passive smoking (category 2B). (2) Intermediate risk group: age ≥50 years, history of smoking or passive smoking exposure ≥20 pack years, no other risk factors. (3) Low-risk group: age <50 years, history of smoking <20 pack-years NCCN guidelines recommend lung cancer screening for the high-risk group, but not for the low- and intermediate-risk groups.