Definition

CYFRA21-1 (Cytokeratin 19 fragment) is a soluble fragment of cytokeratin 19, a subunit of the intermediate filament, one of the structural proteins that form epithelial cells. According to its molecular weight and bidirectional electrophoresis medium electric point, it can be divided into 20 different types. They are divided into two subgroups: class I (acidic proteins) and class II (basic proteins). Cytokeratin is a heteropolymer composed of class I and class II keratins.

Fig. 1 structure of CYFRA-21-1 Antigen

Cytokeratin 19 (CYK-19) is a class I keratin (acidic protein) with a molecular weight of about 40,000 Da, which is the smallest member of the keratin family. CYK-19 is widely distributed on the surface of normal tissues, such as lamellar or squamous epithelium. In malignant epithelial cells, the activated protease accelerates the degradation of the cell, so that a large number of cytokeratin fragments are released into the blood, and their soluble fragments can specifically bind to two monoclonal antibodies KS19.1 and BM19.21, so it is called CYFRA21-1.

CYFRA21-1 is not an organ-specific protein, and it is mainly distributed in tissues or tissues rich in epithelial cells, such as lung, breast, bladder, intestine, uterus, etc. When these tissues undergo malignant transformation, CYFRA21-1 levels in the blood can be seen to increase.

Fig . 2 CYFRA 21-1

Function

Tumor markers are substances that exist in tumor cells or on the surface of cell membranes and are synthesized and secreted into body fluids during the process of tumor occurrence and proliferation, which can reflect the existence and growth of tumors. The more vigorously the tumor grows, the more the corresponding marker is produced; conversely, the tumor growth is inhibited and its production is also reduced.CYFRA 21-1 plays a great role in medicine as a tumor marker.

CYFRA 21-1 is mainly used to monitor the course of non-small cell lung cancer (NSCLC). CYFRA 21-1 is also suitable for monitoring the course of muscle-invasive bladder tumor. CYFRA 21-1 also showed good specificity for benign pulmonary diseases (pneumonia, sarcoidosis, tuberculosis, chronic bronchitis, bronchial asthma, emphysema).

CYFRA 21-1 was initially used in the monitoring of lung cancer, according to different medical literature, it can reach 47% to 61% sensitivity and 95% specificity. Especially for lung squamous cell carcinoma, it is more sensitive than other tumor markers. When combined with CEA, the sensitivity of lung adenocarcinoma detection could be further increased.

If the test value exceeds the upper limit of the reference value, the possibility of lung non-small cell carcinoma and esophageal squamous cell carcinoma should be considered first, and the sensitivity is about 40%-60%. Other cancers such as breast cancer, bladder cancer, head and neck cancer, ovarian cancer, endometrial cancer, and cervical cancer may also cause the increase of CYFRA21-1. People with liver cirrhosis, renal failure, tuberculosis, and acute pneumonia may also have non-specific increases. CYFRA21-1 can also be used in the treatment of lung cancer, esophageal cancer, and breast cancer to help monitor tumor recurrence and evaluate prognosis and treatment response.

Clinical Application

CYFRA21-1 and Non-small Cell Lung Cancer (NSCLC)

Recurrence and metastasis of non-small cell lung cancer are the leading causes of death in lung cancer. Studies have shown that the serum level of CYFRA21-1 in the lung cancer group is significantly higher than that in the benign lung disease group, and the level in the lung squamous cell carcinoma group is significantly higher than that in other types of lung cancer group. In addition, CYFRA21-1 is a good indicator for monitoring lung cancer and suggesting prognosis. If there is an unclear ring shadow in the lungs and the serum CYFRA21-1 concentration is > 30 ng/ml, the likelihood of primary bronchogenic cancer is very high.

CYFRA21-1 and Papillary Thyroid Carcinoma

CYFRA21-1 is a novel tumor marker that is a full-length fragment of CK19. With metastasis of papillary thyroid carcinoma metastases, the level of serum CYFRA21-1 is significantly increased.

CYFRA21-1 and Esophageal Cancer

Esophageal cancer is one of the most common cancers in China, with squamous epithelial carcinoma being the most common. The sensitivity of CYFRA21-1 to lung squamous cell carcinoma is significantly higher than that of adenocarcinoma and small cell lung cancer, and the level of CYFRA21-1 is positively correlated with the number of lymph node metastases.

CYFRA21-1 and Laryngeal Cancer

Studies have shown that the preoperative serum CYFRA21-1 level in the laryngeal cancer group is significantly higher than that in the laryngeal benign lesion group, and the serum CYFRA21-1 level after laryngeal cancer surgery decreases significantly. Therefore, CYFRA21-1 is associated with laryngeal cancer.

Alpha Lifetech Inc. is dedicated to developing CYFRA21-1 diagnostic regents. Alpha Lifetech Inc. is a reputable supplier focusing on research, manufacture and sales of In Vitro Diagnostic (IVD) regents. All the IVD regents offered by Alpha Lifetech Inc. have undergone strict QC validation and are certified by the COA (certificate of analysis). Meanwhile, we can provide customized services according to customers' requirements. Alpha Lifetech Inc. is committed to supplying high-quality, high-sensitivity antigen and antibody products for scientific research and industrial customers. In addition to regular small packages, Alpha Lifetech Inc.'s large-scale fermentation platform also allows us to provide raw material-grade IVD regents for the majority of industrial clients.

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