High cytokeratin 19 fragment antigen may be due to non-small cell lung cancer, esophageal cancer and other factors, but also due to benign diseases such as pneumonia, it is recommended to carry out further pathological tests to clarify. Cytokeratin 19 fragment is a kind of scaffolding protein of epithelial cells, which is mainly distributed in tissues or organs rich in epithelial cells. When malignant changes occur in these tissues, such as non-small cell lung cancer, esophageal cancer, etc., or benign diseases, such as pneumonia, bronchitis, etc., the level of cytokeratin 19 fragment can be seen to be elevated in the blood. Normal human serum concentration <2.0μg/L. For benign diseases the etiology can be treated with medications, such as anti-infective drugs like cephalosporin in case of pneumonia. If malignant lesions are suspected, pathologic examination is recommended. If it is clear that the disease is caused by non-small cell lung cancer or other malignant diseases, the treatment can be targeted. Surgical treatment such as lobectomy and targeted drugs such as bevacizumab can be used to treat lung cancer. It should be noted that the above drugs need to be used under the guidance of clinicians, and unauthorized use of drugs is absolutely prohibited. There are many reasons for the high cytokeratin 19, and the specific disposition should be determined according to the condition, it is recommended to go to the hospital for consultation in time to avoid delaying the condition.