The absence of pain does not exclude the possibility of lung cancer. Early stage patients with lung cancer are basically asymptomatic because there are no sensory nerves in the alveoli, which can only be determined after further examination. The causes of lung cancer mainly include diet, history of lung disease and heredity. Patients usually have symptoms such as blood in sputum, chest pain, fever, etc. In early stage, the most common symptom is coughing, which is often manifested as no sputum or little sputum. When coughing occurs without any cause, it is recommended to go to the hospital in time for examination. If lung cancer is diagnosed, patients should quit smoking in daily life, avoid exposure to second-hand smoke, avoid going to places with polluted air, take proper physical exercise, have balanced diet and family members should pay attention to the patient’s emotion, keep a happy and relaxed mood, have regular checkups and seek medical treatment when they feel uncomfortable.