Mammaglobin is a glycoprotein associated with the human breast, as the gene is expressed solely in the adult mammary gland. A link between the glycoprotein and breast cancer has been reported, as high levels of mammaglobin mRNA are present in human breast cancer cell lines and primary breast cancers. Studies have shown that mammaglobin is a highly specific marker that can aid in determining breast origin in the setting of metastatic carcinoma, as well as correlating with several prognostic factors of breast cancer, including lymph node involvement.

Mammaglobin has been shown to be overexpressed in human breast cancer. Studies suggest that mammaglobin is a relatively mammary-specific and mammary-sensitive marker. Mammaglobin may be valuable in a panel with GCDFP-15 and estrogen receptor in evaluating tumors of unknown primary sites.