The CA 15.3 exam is the exam normally requested to monitor treatment and check for breast cancer recurrence. CA 15.3 is a protein normally produced by breast cells, however, in cancer the concentration of this protein is quite high, being used as a tumor marker.
Despite being widely used in breast cancer, CA 15.3 may be elevated in other types of cancer, such as lung, pancreas, ovary and liver, for example. For this reason, it must be ordered together with other tests, such as molecular tests to evaluate 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 mainly serves to assess the response to breast cancer treatment and to check for recurrence. This test is not used for screening, as it has low sensitivity and specificity. It is generally recommended by the doctor to perform this test before starting treatment and a few weeks after surgery or starting chemotherapy, to check if the treatment is being effective.
The concentration of this protein in the blood is increased in 10% of women in the early stage of breast cancer and in more than 70% of women who have cancer in a more advanced stage, usually with metastasis, being more indicated to perform this test in women who have already been treated or who are undergoing cancer treatment.
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 generally automatic and generates accurate and reliable results in a short time.
The reference value for this test is 0 to 30 U / mL, values above this are already indicative of malignancy. The higher the concentration of CA 15.3 in the blood, the more advanced the breast cancer is. 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 proliferating again, indicating relapse.
High concentrations of CA 15.3 do not always indicate breast cancer, as this protein may also be elevated in other types of cancer, such as lung, ovarian and colorectal cancer, for example. For this reason, the CA 15.3 exam is not used for screening, only for monitoring the disease.
