Cough is often the first symptom of lung cancer, which is mainly characterized by persistent paroxysmal irritating dry cough, high-pitched metallic cough or irritating choking cough with blood in sputum. When accompanied with infection, sputum volume increases and is mucopurulent. 1. Main features of cough: (1) Due to the persistent invasion of malignant tumors into the bronchial wall and the pathological types of tumors are mostly non-mucous, so it is often manifested as a persistent paroxysmal irritating dry cough, which often has the feeling of not being able to cough cleanly, and the sputum volume is small, often dominated by dry cough. (2) Unexplained, prolonged, common cold medicine treatment for a long time does not improve. (3) Changes in the nature of the original cough, the degree of cough aggravation. 2. Cough accompanied by symptoms: (1) Accompanied by blood in sputum or hemoptysis: lung cancer, in the process of continuous growth, intermittently or continuously invades small blood vessels, thus manifesting as intermittent or continuous blood in sputum. If it erodes the wall of large blood vessels, it can cause hemoptysis. (2) Accompanied by infection: when accompanied by infection, the exudation of inflammation will be aggravated, and the amount of sputum will be increased and often be mucopurulent. (3) Accompanied by shortness of breath or wheezing: when the tumor grows into the trachea or bronchus and causes airway obstruction, or when the tumor metastasizes to the hilar lymph nodes and causes the enlarged lymph nodes to oppress the main bronchus or the bronchioles, then there will be dyspnea, shortness of breath, wheezing, and occasionally, wheezing. Early symptoms of lung cancer are not obvious, when lung cancer is suspected, one should seek medical treatment in time to avoid delay in diagnosis and treatment.