CA 15.3, Breast Cancer Marker

CA 15.3 is a protein in the blood which is usually increased in patients suffering from breast cancer. This test is used to monitor the status of breast cancer during & after treatment. Serial testing helps in early detection of spread or recurrence of breast cancer. It is also used as a marker to look for early signs of breast cancer in people at high risk of the disease. It should not be used as a screening test for the population because many other conditions also increase the CA15.3 levels in blood.