Lung cancer usually has no symptoms in the early stage or early stage, and most of them are already in the middle and late stage when typical symptoms appear. The common symptoms are irritating cough, blood in sputum, hoarseness, etc. The best way to detect lung cancer is regular medical checkup. Lung cancer has different types, sites and stages. There are many causative factors leading to lung cancer, such as smoking, environmental pollution, radiation, chronic inflammatory irritation, etc. The most common symptom of most lung cancer patients is cough. It may be caused by the stimulation of bronchial mucosa by cancer cells, which typically manifests as paroxysmal irritating dry cough, and the effect of general cough suppressants is not good. Secondly, the common symptom of lung cancer is cough with blood in sputum: it can be intermittent attacks or persistent attacks. In addition, some patients’ symptoms are chest pain (cancer cells invade pleura, chest wall, nerves, etc.), chest tightness and shortness of breath (cancer tissue obstructs airway), hoarseness of voice (cancer cells invade laryngeal nerve), enlarged lymph nodes in the neck (lymphatic metastasis), etc. Therefore, for early detection, it is necessary to have regular medical checkups and low-dose spiral CT of chest is recommended for early screening.