Non-small cell lung cancer antigen generally refers to non-small cell-associated antigen, i.e., cytokeratin 19 fragment, whose normal value ranges from 0 to 3.3 ng/ml, and 4.25 ng/ml is higher than the normal value, which may be due to malignant tumors, such as non-small cell lung carcinoma, or benign diseases, such as pneumonia. CYFRA21-1 is mainly distributed in organs rich in epithelial cells, such as lung, breast, uterus, intestine, bladder, etc. These tissues will have different degrees of CYFRA21-1 increase when malignant or benign diseases occur. CYFRA21-1 is the preferred tumor marker for non-small cell lung cancer of the lung, and is also seen in breast, bladder, and intestinal cancers. Generally, patients with malignant tumors have higher CYFRA21-1 values, and there is a high likelihood of having bronchopulmonary cancer when >30ng/ml. Elevated CYFRA21-1 can also be seen in pneumonia, tuberculosis, as well as breast, gynecological, gastrointestinal, urinary tract and other benign diseases, but the CYFRA21-1 value is usually only mildly increased, mostly no more than 10ng/ml. CYFRA21-1 value of 4.25ng/ml is more likely for benign diseases, but does not exclude the risk of malignant tumors, and it is recommended that the patient consult the doctor in time and make a comprehensive judgment based on the results of other tests.