CA 72-4 is found on the surface of cancer cells and belongs to the mucin family. CA 72-4 is a tumor marker glycoprotein, which increases in variety of human adenocarcinomas such as gastric, colon, breast, and ovarian cancer. Also, the positive rate of CA 72-4 is significantly higher in the cases with lymph node metastasis. The combination of CA 72-4 with other known serum cancer markers, such as CEA and CA 19-9 (for gastrointestinal cancer) or CA 125 (for ovarian cancer), indicated that an increase in the sensitivity can be achieved without substantial changes in the overall specificity, improving the possibility of monitoring these cancerous patients. CA 72-4 is used as a positive control in various immunoassays (like ELISA, ECLIA) for the detection of variety of cancers.