There are many classifications of lung cancer, which can be classified from anatomical classification and histological classification. The classification is because the pathological characteristics, treatment and prognosis of various lung cancers are not quite the same. Lung cancer does not have any special symptoms in early stage, but only symptoms common to general respiratory diseases, such as chest pain, cough, sputum and blood, low fever and stuffy breath, which can be easily ignored. Specific manifestations of common symptoms in early stage of lung cancer: 1. Chest distension and pain: Chest pain in early stage of lung cancer is light, mainly manifested as boring pain, hidden pain, and its location is not certain, and its relationship with breathing is also uncertain. If the pain is persistent, it means that the cancer may involve the pleura. 2.Cough: Lung cancer usually produces irritating cough because it grows on bronchopulmonary tissues, resulting in respiratory tract irritation. 3.Sputum blood: When tumor inflammation causes necrosis and capillary breakage, there will be a small amount of bleeding, which is often mixed with sputum and appears intermittently or intermittently. Many patients with lung cancer visit the doctor because of sputum blood. 4.Low fever: After the tumor blocks the bronchus, there is often obstructive lobe of lung, the degree of which varies, the lighter one only has low fever, the heavier one has high fever, which can be temporarily improved after medication, but will recur soon.