Clinical Significance

CYFRA21-1 is a soluble fragment of CK19 protein. CK19 has a molecular weight of 40KDa and is an acidic keratin. CK19 is widely distributed on normal tissue surfaces such as lamellar or squamous epithelium. In malignant epithelial cells, activated proteases accelerate cellular degradation, resulting in the release of large amounts of cytokeratin fragments into the blood. The soluble fragment of CK19 can be combined with two mAbs KS19.1 and BM19.21 (BM19.21 is a subclone of KS19.2), so it is called CYFRA21-1. The molecular weight of CYFRA21-1 is about 30 KDa, and CYFRA21-1 is highly expressed in malignant lung cancer tissues, especially in lung squamous cell carcinoma.
CYFRA21-1 is currently considered to be a tumor marker mainly used for the detection of lung cancer, especially for the diagnosis of non-small cell lung cancer (NSCLC). The sensitivity of CYFRA 21-1 for the diagnosis of various types of lung cancer was as follows: squamous cell carcinoma>adenocarcinoma>large cell carcinoma>small cell carcinoma. In addition, CYFRA21-1 has a certain positive rate for other tumors, such as invasive bladder cancer, head and neck cancer, breast cancer, cervical cancer, and digestive tract tumors.

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