Cancer Antigen (CA) 15-3 Blood Test

This Cancer Antigen (CA) 15-3 Blood Test is used for monitoring the response to invasive breast cancer treatment and monitoring the recurrence of the disease.

Description

CA 15- 3 is an antigen or a substance that stimulates the defense system of your body. Some cancer cell types release antigen CA 15- 3 into the blood. This test is used to track certain cancers. CA 15-3 is not used as a screening test or a diagnostic test to find breast cancer.

Breast cancer is the cancer that most likely releases CA 15-3, particularly after treatment with breast cancer. Antigens like CA 15-3 that provide cancer information are called tumor markers.

This test may be needed if: 

• A diagnosis of breast cancer has been made, and monitoring of treatment is necessary.

• Treatment of breast cancer is completed, and confirmation is needed to find out if the cancer has come back or spread.

It is important to know that having a positive blood test for CA 15-3 does not mean that you have breast cancer or that your breast cancer has returned. Additional conditions can lead to CA 15-3 in your blood.  Non-cancerous breast, ovary and liver conditions can lead to an increase in CA 15- 3.

In general, increased values can indicate the progression or recurrence of the disease. Decreasing values may mean the regression of the disease.