Infectious fever is the most common cause of fever in patients with advanced lung cancer. This is because the malignant tumor obstructs the bronchi and branches, causing the distal lung tissues to be unable to ventilate and excrete sputum, and the nutrients in sputum are the best medium for bacteria. The chance of infectious fever in central type lung cancer is higher than that in peripheral type lung cancer. 3. Drug-related fever Many drugs will be used in the treatment of advanced lung cancer, such as interferon, interleukin II, tumor necrosis factor, colony-stimulating factor, tumor vaccine and other biological agents can cause fever. A few patients may develop fever during the use of some chemotherapy drugs and anti-tumor Chinese medicine. This is clinically called granulocytopenia or deficiency fever. This kind of fever is actually caused by secondary infection due to immune deficiency.5. Combined tuberculosis It is not common for advanced lung cancer patients to have combined tuberculosis activity because the dormant Mycobacterium tuberculosis is active again due to the decline of immunity of the patient. Therefore, recurrent fever in advanced lung cancer patients needs to be judged comprehensively based on the patient’s medical history, medication history, other symptoms, fever pattern and CT examination, and actively diagnosed and treated according to the etiology.