Extensive screening of lung cancer and proactive detection of early stage patients, thus early diagnosis and treatment, can greatly prolong patients’ survival. Regular annual chest X-ray examinations and sputum exfoliative cell examinations are conducted for high-risk groups, long-term smokers and those with long-term exposure to carcinogenic agents. The following groups are generally considered as high-risk groups for screening: (1) Men and women over 45 years old. (2) Those who smoke more than 20 cigarettes per day and have smoked continuously for more than 10 years. (3) Areas with high incidence of lung cancer, such as factories, mines, workshops, etc. (4) Workers with long-term exposure to lung cancer-causing substances and more than 10 years of service; for example, tar workers, asbestos miners, those exposed to radioactive substances, etc. (5) Those who have a family history of lung cancer and have smoked and been exposed to carcinogenic substances for a long time, and are over 40 years old. (6) Patients with a history of chronic lung disease. For the above-mentioned people, one X-ray chest film should be taken every year.