CK20 positive is not good, this positive result mostly represents that there is keratin expression, indicating that there is a malignant tumor of epithelial tissue origin, which requires prompt medical attention and is serious. CK refers to keratin, which is mainly derived from epithelial tissue, CK20 is a marker of tumor cells, positive mostly represents that there are tumors of epithelial tissue origin and high malignancy, such as gastrointestinal adenocarcinomas, ovarian mucinous tumors, which is not good.Positive CK20 also needs to be combined with relevant parts of the CT, NMR, pathological examination, etc., in order to make a definitive diagnosis, in order to assess the source of the tumor, the stage, and provide a plan for the subsequent treatment. Provide a plan for the subsequent treatment. However, not all tumors are CK20-positive, such as squamous carcinoma, breast cancer, lung cancer, etc. can be CK20-negative, therefore, we cannot diagnose oncological diseases by CK20 alone, imaging and pathological examination are essential. When the CK20 test shows obvious abnormality, it is necessary to actively consult the doctor and follow the doctor’s advice for further diagnosis and treatment.