cyfra refers to cytokeratin, a tumor marker mainly used in lung cancer. It plays an important supporting role in the diagnosis of lung cancer. It may also be related to diet, environmental factors or patients with other lung lesions, not sure that it is necessarily a tumor. Lung cancer is a kind of malignant tumor originated from epithelial tissue, and its morbidity and mortality rate rank first in China. Symptoms of lung cancer include chronic cough, hoarseness, coughing up blood, chest pain, chest tightness and shortness of breath, and frequent lung infections. The causes of lung cancer include long-term smoking, long-term passive inhalation of second-hand smoke, harmful substances in the working environment, underlying diseases such as chronic obstructive pulmonary disease (COPD), or family history of lung cancer, which may lead to higher incidence rate. It is recommended that when the patient coughing, coughing up blood and other symptoms should be immediately to the regular hospital for consultation, follow the doctor’s instructions for relevant examinations, which may have cyfra auxiliary diagnosis. According to the results of the examination to clarify the diagnosis. It is recommended not to smoke, smoking is harmful to health.