Cancer Antigen 15-3 (CA 153)

General Information

CA 15-3 is a transmembrane glycoprotein encoded by the MUC1 gene. It is defined by reactivity with 2 monoclonal antibodies, i.e., DF3 and 115D8 in a sandwich immunoassay. It is primarilty used as a marker of breast cancer.

Elevated CA 15-3 levels can also be seen in bronchial carcinmona, ovarian carcinoma, pancreatic carcinmona, colo-rectal carcinmoa as well as in non-malignant conditions such as chronic active hepatitis, liver cirrhosis, sarcoidosis, hypothyroidism, and megablastic anemia.

Due to this, and because the incidence of CA 15-3 elevation in breast cancer is low (23%), CA 15-3 should not be used to diagnose or screen for primary breast cancer. In combination with radiology and clinical examination, CA 15-3 may be used to monitor chemotherapy in patients with advanced breast cancer. For patients with nonevaluable disease, sustained increases in marker concentrations suggest progressive disease. 2 successive increases (e.g., each >30%) are likely to indicate progressive disease.