Not necessarily. Mucous sputum in the throat may be caused by chronic bronchitis, chronic obstructive pulmonary emphysema, lung abscess, bronchial dilatation, etc. Mucous sputum may be present when lung cancer is accompanied by infection, and mucinous adenocarcinoma may also have a large amount of mucous sputum, which can not be excluded from the possibility of lung cancer. 1. Chronic bronchitis: the main symptoms are cough, sputum or wheezing. Coughing is mainly in the morning, and there is cough or sputum at night, usually white mucus sputum, occasionally with blood, and sputum can be stimulated when the body position changes. 2. Chronic obstructive pulmonary emphysema: the main cough is obvious in the morning, with bouts of cough or sputum at night, white mucus sputum is the main sputum, the sputum volume increases in the acute attack period, and purulent sputum can be present. 3. Lung abscess: early symptoms of pneumonia, i.e. fever, night sweats, fatigue, coughing mucus sputum or mucopurulent sputum. After about 1~2 weeks, it manifests as high fever, worsening cough and coughing up a large amount of purulent sputum. 4. Bronchiectasis: manifested by persistent or recurrent cough and sputum. The sputum is often mucous, mucopurulent sputum, which may be yellowish green and divided into 4 layers after resting. With the aggravation of infection, the amount of sputum may be increased, and mucus sputum may be increased. 5. Lung cancer:It is often manifested as irritating dry cough without sputum or little sputum, and there may be a large amount of mucus sputum when lung cancer is accompanied by secondary infection. Mucinous adenocarcinoma can have a large amount of mucous sputum. In addition, pneumonia, tuberculosis or chronic rhinitis, sinusitis caused by backflow of nasal mucus can also be accompanied by increased mucus sputum. If you have mucus phlegm in your throat, you should go to the hospital for a comprehensive examination and treatment under the guidance of a specialist.