Lung cancer may lead to suppuration after localized necrosis occurs. 1. Lung cancer is a common malignant tumor of the respiratory system, which can be caused by various factors such as smoking and heredity. When the tumor is large and necrosis occurs inside the tumor, it may lead to suppuration of the cancerous lesion. If the lesion is connected to the trachea, the clinical symptom of coughing up pus and sputum may occur. In order to avoid this kind of situation, after diagnosing the disease, the patient should go through surgery, radiotherapy, chemotherapy and other methods of treatment in time. 2. However, coughing up pus and sputum does not mean lung cancer, but also non-cancerous diseases such as lung abscess, which may be accompanied by cough, sputum with foul smell, repeated hemoptysis and other symptoms. Therefore, patients should seek medical treatment in time after discomfort occurs as well as clarify the cause of disease early for precise treatment.