CA 15-3

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.

Physiology

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.

Indication

pending

Elevated CA 15-3 levels

• breast adenocarcinoma
• ovarian carcinoma
• pancreatic carcinoma
• gastric carcinoma
• bronchogenic carcinoma
• benign breast disease
• liver disease
  • chronic active hepatitis
  • cirrhosis
• sarcoidosis
• hypothyroidism
• megaloblastic anemia