Individual test · Labcorp 483404

Cancer Antigen (CA) 15-3 (Serial Monitor)

This test measures the amount of CA 15-3, a protein often released into the bloodstream by breast cancer cells. It is most commonly used to monitor how well treatment is working for advanced breast cancer or to check for signs that the disease has returned. By tracking these levels over time, doctors can see if the cancer is responding to therapy or continuing to grow. However, this test cannot diagnose breast cancer by itself or screen for the disease in healthy people, as other non-cancerous conditions can also cause high levels.