Who is at high risk for lung cancer? According to the American University Clinical Medical Association, the definition of people at high risk for lung cancer is as follows: people aged 55-74 years who are current smokers with a smoking index of at least 30 packs/year, or former smokers with a smoking index of at least 30 packs/year who have quit smoking less than 15 years ago. For those aged 55 to 80 years at high risk for lung cancer, annual low-dose spiral CT screening of the lungs; for those with a 30-year smoking history who still smoke or those who have quit smoking but have not quit for more than 15 years, the benefits of annual low-dose spiral CT screening outweigh the risks; once they have quit smoking for more than 15 years or have other conditions that affect life expectancy or interfere with the performance of lung cancer surgery, they lung cancer screening can be discontinued.