The symptoms of fever in patients with advanced stage of lung cancer are mostly considered to be related to tumor fever, myelosuppression, pneumonia and so on. 1. Tumor fever: most tumor patients will release some inflammatory mediators due to tumor necrosis, which in turn will cause inflammatory reaction related to immunity. At this time, patients will have fever. 2. Myelosuppression: if fever occurs after chemotherapy, it is considered to be related to myelosuppression caused by chemotherapy, and the patients will have the decrease of neutrophils, which will lead to fever. 3. Pneumonia: when the patient is in the advanced stage of cancer, the immunity is low, so it is easy to be infected with pneumonia, which will cause fever. To determine the specific cause of the disease, it is necessary to go to the hospital as soon as possible, and do lung CT, blood routine and other tests.