Mainly associated tumors: Adjuvant markers for malignant tumors, especially in chronic lymphocytic leukemia, lymphocytic sarcoma, and multiple myeloma. Other related tumors: lung cancer, breast cancer, gastrointestinal tract cancer and cervical cancer. Other influencing factors: it is elevated in renal failure, various hematologic diseases and inflammation, and can be elevated in a variety of diseases. Therefore, it should be excluded that serum β2-MG is elevated due to certain inflammatory diseases or glomerular filtration function bottoming out. β2-MG is a co-marker of malignancy and a tumor-associated antigen on some tumor cells. In malignant hematological diseases or other substantial carcinomas, mutant cells synthesize and secrete β2-MG, which can lead to a significant increase in the concentration in the patient’s serum, especially in lymphatic system tumors such as chronic lymphocytic leukemia, lymphocytic sarcoma, multiple myeloma, etc., and also can be seen to be elevated in lung, breast, gastrointestinal, and uterine cervix cancers. Since serum β2-MG can be significantly higher than normal in the early stage of tumor, it is helpful to identify benign and malignant tumors. It has been reported that the ratio of β2-MG in ascites to serum in malignant diseases is significantly correlated, and if the ratio of the two is greater than 1.3, it is considered to be a manifestation of cancer. Serum β2-MG can be elevated not only in renal failure, various hematologic diseases and inflammation, but also in a variety of diseases, so the increase of serum β2-MG due to certain inflammatory diseases or reduced glomerular filtration function should be excluded. Detection of β2-MG in cerebrospinal fluid is of particular significance in the diagnosis of meningeal leukemia.