According to the chemical and biological properties of tumor markers, they can be broadly classified into seven categories: 1. Enzymes TM: such as alkaline phosphatase (ALP), lactate dehydrogenase (LDH), neuron-specific enolase (NsE), prostate-specific antigen (PSA), glutathione-S-transferase ((GST), γ-glutamyl transpeptidase (γ-GT). 2.HormonesTM: such as calcitonin (CT), human chorionic gonadotropin (HCG), catecholamines, hormone receptors, estrogen, etc. 3.Embryonic antigensTM: such as alpha-fetoprotein (AFP), carcinoembryonic antigen (CEA), etc. (These substances are proteins that are only present in fetal life and gradually decline in adulthood). 4, glycoprotein class antigen TM: all with CA belong to this category (CAl25, CAl5-3, CAl9-9, CA50, CA242). 5.Protein class TM: such as keratin, tissue peptide antigen, squamous cell carcinoma antigen, ferritin, etc. 6.Gene related TM: such as ras gene protein, myc gene protein, erbB-2 gene protein, p53 gene protein, bcl gene protein, etc. 7.Other TM: sialic acid and sialic acid acyltransferase, polyamines, etc.