The indicator that has important value for the diagnosis of non-small cell lung cancer is cytokeratin 19 fragment, so non-small cell lung cancer antigen 3.55 should refer to the cytokeratin 19 fragment indicator of 3.55ng/ml, which is higher than the normal value, and is more important if it is caused by malignant tumors, while the condition can be mild or serious if it is caused by benign diseases. Cytokeratin 19 fragment, also known as CYFRA21-1, is a marker for detecting lung cancer tumors. Non-small cell lung cancer antigen is found mainly in organs rich in epithelial tissue such as the lungs, uterus, and bladder, and when benign or malignant lesions occur in these organs, there is an elevation of CYFRA21-1. The normal value of CYFRA21-1 should be <3.3ng/ml and 3.55ng/ml is above normal. If the elevation is caused by malignant tumors such as non-small cell lung cancer, breast cancer, cervical cancer, bladder cancer, etc., it is more serious and needs to be treated as soon as possible with surgery, radiotherapy and chemotherapy. If the elevation of CYFRA21-1 is caused by pneumonia, tuberculosis, urological, gynecological diseases, etc., the condition may be serious, such as severe pneumonia, tuberculosis, etc., which may cause life-threatening diseases if not treated in time. However, the condition may also be mild, such as cystitis, acute mastitis, etc. It can be cured by taking antibiotics such as levofloxacin and penicillin as prescribed by the doctor. There are many reasons for the elevation of antigen in non-small cell lung cancer, so it is suggested that patients should combine with other examination results to comprehensively judge the cause of the disease and follow the doctor's instruction to carry out treatment.