CA 15-3, Human Breast Adenocarcinoma

CA 15-3 (Cancer Antigen 15-3) is a breast tumor marker. CA15-3 is a glycoprotein that is secreted by breast cancer cells. While the level of CA15-3 is rarely elevated for patients with early-stage or localized cancer, the majority of patients with metastatic breast carcinoma have shown elevated serum levels of CA15-3.