CA 15-3

Dr Daniel J Bell et al.

Carcinoma antigen 15-3, usually shortened to CA 15-3 is a tumor marker used in monitoring breast cancer. The test detects levels of MUC-1, a mucin protein in the blood. MUC-1 is thought to be important in the invasiveness and metastasization of cancer cells.

MUC-1 is a normal epithelial cellular protein localized to the apical membrane. In the cancer cell MUC-1 is present on the complete membrane, and also intracytoplasmic. Abnormal genetic expression also results in changes to the sugar side chains such that various protein antigens are uncovered, increasing the likelihood of antibodies cross-linking the MUC-1. The up-thrust of these changes is a greater concentration of MUC-1, which is more antigenic, therefore it can be employed as a tumor marker.


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Article information

rID: 66167
System: Breast, Oncology
Section: Pathology
Synonyms or Alternate Spellings:
  • Carcinoma antigen 15-3

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