Early stage of lung cancer is often dry cough or irritating dry cough with little sputum. When the tumor causes bronchial stenosis, as the mass in the bronchial tube is a foreign body, it will cause the symptom of coughing, which is mostly persistent, and sometimes it will be a high-pitched metallic sounding cough or irritating choking cough, and there are some types of lung cancer accompanied by a large amount of mucus sputum, such as fine bronchiolo-alveolar carcinoma, which will show a large amount of mucus or foam-like sputum. If secondary lung infection occurs, the amount of sputum will increase, yellow or bloody sputum may appear, and anti-infection treatment needs to be given. Blood in sputum may be due to hemoptysis caused by tumor surface erosion and necrosis.