Most of the precursors of lung cancer from smoking or all lung cancer precursors are coughing and coughing up sputum, especially blood in sputum. Blood in sputum is the most important precursor indicating the presence of lung cancer. Patients may also have chest tightness, shortness of breath, fever, chest pain, or other joint pain in the limbs. However, once the above symptoms appear, most of them are not early stage lung cancer, but middle or late stage. Early lung cancer can be detected by physical examination, especially for those who smoke a lot, smoke for a long time, have family history of tumor, have special occupation, or have calcified lesions in the lungs, which are high-risk groups of lung cancer, they should develop the habit of regular physical examination. It is recommended that at least low-dose spiral CT screening of the lungs should be performed for those over 40 years of age, long-term smoking, family history of tumor or special occupational settings, which can detect early stage lung cancer without any symptoms. This part of lung cancer can reach a very good prognosis through treatment, with a five-year survival rate of 80%-90%. If the patient has symptoms, even if the treatment is timely, the five-year survival rate in the middle stage decreases significantly.