What does tumor marker mean?

Tumor markers are chemical substances that reflect the existence of tumors. They either do not exist in normal human tissues but are limited to embryonic tissues, or their content in tumor tissues greatly exceeds that in normal tissues. Their existence or quantitative quantity can indicate the nature of tumors, and can understand the occurrence, cell differentiation, and cell function of tumor tissues to help diagnose and classify tumors, judge prognosis, and guide treatment. At present, tumor markers mainly include several categories, the first category is carcinoembryonic protein, the second category is tumor associated antigen, the third category is special plasma protein, the fourth category is enzyme, and the fifth category is hormone.