Phlegm in the throat all the time is not necessarily lung cancer, but is more commonly found in respiratory tract infections such as bronchitis, tracheitis, pneumonia and other conditions. If the phlegm is caused by cough of lung cancer, not only the coughing symptom will appear, but also the feeling of pressure in front of the chest, and lung cancer mainly takes irritating dry cough as the first symptom, and it is possible to cough without phlegm or with little phlegm, and some patients will be accompanied by blood. Therefore, if you have symptoms such as chest tightness, vague pain, dry cough without sputum with blood for a long time, it may be lung cancer. If there is only phlegm in the throat, it is not necessarily cancer, and it is recommended to do chest CT to help judge. Coughing with phlegm is more commonly a lung infection, so sputum culture and drug sensitivity test can be done to select appropriate drugs for treatment according to the type of infection and sensitive antibiotics. Patients who always have phlegm in the throat should eat as light as possible, avoid eating greasy and stimulating foods, reduce the amount of smoking or quit smoking, and have regular checkups.