Cancer Antigen CA 15-3



Quest Diagnostics Test Code: 5819

CA 15-3 is used for monitoring patients with metastatic breast cancer and certain ovarian cancers. The CA 15-3 values from sequential samples have a high correlation with the clinical course in most patients with metastatic breast cancer.

Cancer antigen (CA) 15-3 is a protein that is typically produced in the breast tissue of healthy humans. When there is breast cancer, there is rapid growth of breast cells, which give of much higher amounts of CA 15-3. Because of this, it is helpful in guiding the efficacy of treatment in women with breast cancer. However, because this increase in CA 15-3 production is not present in all women with breast cancer, and CA 15-3 can also be elevated in other types of cancer, it is not a useful screening tool to detect breast cancer in women. Therefore, the test is mainly used as a surveillance tool in women who already have a diagnosis and are on treatment to see if the treatment is effective.

This test is performed in following conditions such as:

• In people who already have breast cancer diagnosed, this is to help determine cancer characteristics and treatment options
• Women with breast cancer who are on treatment like radio or chemotherapy


Specimen Collected
  • Blood
Estimated Time Taken

Turnaround for this test is typically 1-2 business days.