The detection of tumor marker (TM) is of great significance in aiding the diagnosis of tumor and determining the prognosis, regression and evaluation of the efficacy of tumor. However, many reports have overstated the role of tumor markers and misled some patients’ understanding of the significance of tumor marker testing. The so-called tumor markers are a class of substances produced by tumor cells themselves or by the body’s response to tumor cells during tumorigenesis and proliferation, reflecting the existence and growth of tumors, including proteins, hormones, enzymes (isoenzymes), polyamines and oncogene products, etc. The Bence-Jones protein discovered in 1846 was applied to After the discovery of AFP in 1963 and CEA in 1965, the concept of tumor markers was first introduced by Herberman at the Conference on Human Immunity and Tumor Immunodiagnosis held by NCI in 1978, tumor markers have been widely used in clinical practice. At present, more than 100 kinds of tumor markers with clinical significance have been discovered. The ideal tumor markers should have the following characteristics: (1) high sensitivity; (2) good specificity; (3) related to the severity of disease, tumor size or stage; (4) can monitor the effect of tumor treatment; (5) monitor the recurrence of tumor; (6) predict the prognosis of tumor. However, so far, there is no “ideal” tumor marker. Therefore, clinical care should be taken not to misjudge the results of tumor markers.