There are many reasons for chirping sound in breathing in advanced stage of lung cancer, such as tracheal compression, bronchial asthma, inflammation of respiratory tract and so on. 1. Tracheal compression: tumors may be formed around lung tissues and trachea in the late stage of lung cancer, and if the tumor presses the trachea, it will lead to the phenomenon of chirping sound in breathing in the late stage of lung cancer. 2. Bronchial asthma: bronchial asthma can also cause the phenomenon of chirping sound in late stage of lung cancer, which may be related to the contact with allergens, and some lung cancer patients themselves have the history of asthma. 3. Inflammation of respiratory tract: If lung cancer is combined with inflammation of respiratory tract, such as bronchitis and pneumonia, it will also cause chirping sound in late stage of lung cancer, and accompanied by coughing and sputum. There are many reasons for chirping sound in late stage of lung cancer, after symptoms appear, it is suggested that patients should go to the hospital in time and take standardized treatment according to doctor’s advice, and should not ignore the symptoms and take them lightly.