The CA 15.3 exam is the examination usually required to monitor the treatment and to check for recurrence of breast cancer. CA 15.3 is a protein normally produced by mammary cells; however, in cancer the concentration of this protein is quite high, being used as a tumor marker.
Although it is widely used in breast cancer, CA 15.3 may be elevated in other types of cancer, such as the lung, pancreas, ovary and liver, for example. Therefore, it should be requested along with other tests, such as molecular tests for evaluation of gene expression for breast cancer and tests that evaluate the estrogen receptor, HER2. See which tests confirm and detect breast cancer.
What is it for
The CA 15.3 exam is mainly used to evaluate the response to breast cancer treatment and to check for recurrence. This test is not used for screening because it has low sensitivity and specificity. It is usually recommended by the doctor to perform this test before starting treatment and a few weeks after surgery or start of chemotherapy to see if the treatment is being effective.
The concentration of this protein in the blood is increased in 10% of the women in the early stage of breast cancer and in more than 70% of the women who have the cancer in a more advanced phase, usually with metastasis, being more indicated the accomplishment of this examination in women who have already been treated or are being treated for cancer.
How is done
The test is performed only with the person's blood sample and does not require any preparation. The blood is collected and sent to the laboratory to be processed and analyzed. The analysis process is usually automatic and yields accurate and reliable results in a short time.
The reference value for this test is 0 to 30 U / mL, values above that are indicative of malignancy. The higher the concentration of CA 15.3 in the blood, the more advanced is breast cancer. In addition, the progressive increase in the concentration of this protein may indicate that the person is not responding to treatment or that the tumor cells are re-proliferating, indicating relapse.
Not always high concentrations of CA 15.3 indicate breast cancer, as this protein may also be elevated in other cancers, such as lung, ovary and colorectal cancer, for example. For this reason, the CA 15.3 test is not used for screening only for disease monitoring.
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