Cy211, or cytokeratin 19 fragment, is high enough to indicate certain malignant tumors, such as non-small cell lung cancer, breast cancer, bladder cancer, etc., or certain benign diseases, such as chronic bronchitis, tuberculosis, etc. It is recommended to consult a specialist. Cytokeratin 19 fragment is mainly distributed in organs or tissues rich in epithelial cells, such as breast, lung, bladder, uterus, intestines, etc. If malignant transformation occurs, high CY211 can be seen.The normal value of CY211 is <2.0ug/L, and the results may vary depending on the machine. CY211 is the preferred tumor marker for non-small cell lung cancer, and is mostly used for differential diagnosis of non-small cell lung cancer and assessment of prognosis. It has the highest positivity rate in squamous cell lung cancer, and can be combined with squamous epithelial cell carcinoma antigen and carcinoembryonic antigen to help clarify the typology of lung cancer, etc., and also be used for monitoring the therapeutic efficacy of lung cancer. In addition, high CY211 can be found in breast cancer, colorectal cancer and prostate cancer. CY211 may also be elevated in certain benign diseases, such as tuberculosis, chronic bronchitis, gynecological diseases, etc., but generally the elevation is not obvious, and is often less than 10ug/L. If CY211 is elevated, it should be examined in time and treated actively.