Firstly, the cough of lung cancer is mainly characterized by a high pitch cough, accompanied by metallic sound while coughing and blood in sputum; the cough of chronic pharyngitis is mainly longer, mostly 1-2 months, or even up to several years or decades. Secondly, chronic pharyngitis can be characterized by dry throat, itchy throat, throat-clearing cough, frequent but not violent cough, etc.; the cough of lung cancer is not characterized by the above-mentioned manifestations. Thirdly, lung cancer cough is often accompanied by chest pain, as well as blood in sputum or even fresh blood, irritating dry cough and paroxysmal violent cough; while chronic pharyngitis often does not have the above clinical manifestations. Fourthly, CT examination of lung or bronchoscopy is mainly done to detect occupying lung lesions as well as to confirm the diagnosis of lung cancer; while CT of lung in chronic pharyngitis is normal.