The main symptoms of lung cancer include persistent cough, chest pain, hemoptysis, shortness of breath, wheezing or hoarseness, weight loss, fatigue, pestle and mortar finger, and uremia. In fact, when there are symptoms, 80% of them are already in advanced stage or lost the chance of surgery. The vast majority of early stage lung cancer has almost no obvious signs and symptoms. They are detected by regular physical examinations or ad hoc physical examinations for other health problems. One of the main reasons why many patients also have regular physical examinations but fail to be detected in time is the failure to have a chest CT. Imaging repeatedly shows inflammation in the same area of the lung, and chest imaging reveals an occupying shadow in the lung. Experts recommend early diagnosis at a specialist hospital when there is an unexplained persistent cough, or when symptoms become severe compared to previous coughs. Precautions: 1. Long-term heavy smoking; tumor patients in the family; age 40 or above; special attention. 2. Go to a specialist, preferably for CT examination. 3. Do not go to non-specialized clinics and do not believe that a blood test can tell cancer.