CA15 3 Cancer Antigen
Category:
CA-15-3(Cancer Antigen)
Description
This test is given during or after treatment for breast cancer. It is useful in monitoring advanced breast cancer and your response to treatment. CA 15-3 is not a blood test that screens for breast cancer. It is a tumor marker test that is helpful in tracking cancers that overproduce CA 15-3.
Breast cancer starts in the cells of the breast in women and men. Worldwide, breast cancer is the second most common type of cancer after lung cancer and the fifth most common cause of cancer death.
CA 15-3 is a protein normally produced on breast tissue, and it does not cause breast cancer. If a cancerous tumor (cells growing out of control) is present, levels of CA 15-3 may increase as the number of cancer cells increase. Tumor cells will shed copies of the CA 15-3 protein, which can be measured by this blood test and by a related test of cancer antigen 27.29 (CA 27.29).
Not every breast tumor causes a rise in CA 15-3, so for some tumors that do not produce CA 15-3 or with early-stage breast cancer, this test is not useful. In patients with metastatic breast cancer, CA 15-3 can be found in 50 to 90% of all cases.
Its concentration is measured by means of analysis of a blood sample drawn from the vein in the arm.
Purpose of the test
This tests measures the level of CA-15-3 in blood in order to help monitor treatment for breast cancer.
After completed treatment for breast cancer, the doctor may test blood for CA 15-3 on a regular schedule to see if levels of this antigen are rising or remaining steady. Rising levels of CA 15-3 may indicate a recurrence of breast cancer, but since other conditions can cause higher levels of this antigen, the test results must be taken in to consideration with the results of imaging studies, symptoms and other tests for hormone sensitivity, HER2/neu and BRCA genes.
Reference range values
0-31 U/mL
Abnormal findings
In general, the higher the CA 15-3 level the more advanced the breast cancer and the larger the tumor burden. In metastatic breast cancer, the highest levels of CA 15-3 are seen when the cancer has spread to the bones and/or the liver.
Mild to moderate levels of CA 15-3 also are seen in a variety of conditions, including liver and pancreatic cancer, cirrhosis, and benign breast disorders as well as in a certain percentage of apparently healthy individuals.
Normal CA 15-3 levels do not ensure that a patient does not have cancer. It may be too. In addition, 25% to 30% of individuals with advanced breast cancer have tumors that do not show high CA 15-3.
Pregnancy and lactation also increase levels of CA 15-3. Several noncancerous conditions (benign breast or ovarian disease, endometriosis, pelvic inflammatory disease and hepatitis) can rise levels of CA 15-3.