Taiwan Real-world LDCT Screening Behavior and Outcome Research for High Risk Subjects Based on Health Promotion Administration

Inclusion Criteria: Group 1: Previous heavy smokers Age 50 to 80 years, meet both criteria in the followings. 1. Cigarette smoking of at least 20 pack-years 2. With successful smoking cessation history (stopping smoking for more than 6 months), but less than 15 years Group 2: First-degree relatives of lung cancer patients 1. aged more than 50 years 2. age less than 50 years old, but older than the age at diagnosis of the youngest lung cancer proband in the family Group 3: With other high-risk occupational or environmental factors Age 50 to 80 years, meet one or more of the following criteria. 1. air-pollution exposed occupations (such as traffic policemen, and street cleaners….) for at least 10 years 2. cooking index ≥ 110, defined as 2/7 \* days cooking by pan frying, stir-frying, or deep frying in one week \* years cooking. 3. cooking without using ventilation for more than 20 years 4. history of pulmonary tuberculosis and complete anti-tuberculosis treatment with intervals more than 5 years before this study Exclusion Criteria: 1. previous history of lung cancer 2. another malignancy except for cervical carcinoma in situ or non-melanomatous carcinoma of the skin within 5 years 3. an inability to tolerate transthoracic procedures or thoracotomy 4. chest CT examination was performed within 18 months 5. hemoptysis of unknown etiology within one month 6. body weight loss of more than 6 kg within one year without an evident cause 7. a known pregnancy 8. Not capable of understanding or responding to the written questionnaire even through the help from the study team