The precursors of laryngeal cancer have different clinical manifestations depending on the location of laryngeal cancer, mainly including the following: 1. hoarseness of voice, which is persistent and gradually worsening; 2. foreign body sensation or pain in the throat, which is manifested as foreign body sensation in the throat in the early stage of supraglottis cancer and should be distinguished from chronic pharyngitis; 3. cough and blood in sputum, which is easily caused by coughing with the enlargement and rupture of laryngeal cancer; 4. dyspnea, which is a symptom in the later stage; 5. metastasis of cervical lymph nodes.