CA- 15.3 (Breast Cancer Marker)

CA-15.3 (Cancer Antigen 15.3) is a protein released into the bloodstream by certain breast cancer cells. This test is mainly used for monitoring patients already diagnosed with breast cancer to assess disease progression, recurrence, or response to therapy. Elevated CA-15.3 levels may be seen in advanced or metastatic breast cancer; however, mild elevations can also occur in benign breast conditions, liver disease, ovarian cancer, or lung cancer. It is not recommended as a screening test for early breast cancer but is valuable for follow-up and treatment planning when interpreted alongside clinical findings and imaging studies.