In advanced stage of lung adenocarcinoma, there is always sputum but not coughing much, which may be caused by airway blockage by tumor, or by sputum thrombus obstruction, or by patient’s weakness and respiratory muscle weakness. 1. Airway blocked by tumor: if airway is blocked by tumor in advanced stage of lung adenocarcinoma, it may lead to respiratory difficulties, and patients will have symptoms of sputum but not coughing much because it is difficult for airflow to pass through airway. 2. Obstruction by phlegm plugs: when the airway is not smooth and easy to secrete phlegm in advanced stage of lung cancer, phlegm plugs can block the airway, so the patient will have the symptom of coughing up phlegm but not coughing much. 3. Weakness of respiratory muscles: patients with advanced lung adenocarcinoma tend to be thin due to the consumption of cancer, these patients are weak and their respiratory muscles are weak, so they are not able to cough up sputum, so they may have the symptom of coughing up sputum but not coughing much. In addition to the above factors, other reasons may also lead to the symptom of having sputum but not coughing much, if the symptom continues to be unrelieved, the patient should consult a doctor for treatment in time.