Fever of 39℃ in lung cancer is usually not aggravated by lung cancer itself, but often caused by co-infection, and often combined with cough, yellow sputum, chest pain, shortness of breath, etc. It can also be caused by secondary infection caused by cancer affecting or blocking bronchial cavity and difficulty in discharge of secretions. In advanced cases, cancer fever is sometimes caused by cancer necrosis and toxin absorption, and the body temperature is often below 38℃, and anti-inflammatory treatment is ineffective. Patients with lung cancer may show wasting and cachexia due to tumor toxins and consumption, and loss of appetite due to cancer pain, and this condition often has decreased immunity and is easily combined with bacterial infection. There are also some lung cancer patients, not because of the deterioration and aggravation of cancer itself, but because of the combination of underlying diseases, such as chronic obstructive pulmonary disease, hypertension, etc. Lung infection induces respiratory failure, hypertension, stroke or infectious shock to appear aggravated and even life-threatening.