Breast Cancer Diagnosis: An Overview of the CA 15-3 Test and Its Results
CA 15-3 is a protein that breast cells produce, and a blood test can be used to check a person's CA 15-3 levels. This test is often referred to as a cancer antigen breast test or a CA breast test, and doctors may also call it a tumor marker.
A person may have a CA 15-3 test if they are currently undergoing treatment for invasive breast cancer or have had this treatment in the past. The test is done by taking a sample of blood from a vein in the arm and sending it to a laboratory for testing.
The CA 15-3 test can help a healthcare professional determine how well treatment is working or check for breast cancer recurrence. However, it is important to note that elevated CA 15-3 levels can result from various health issues beyond breast cancer. These include other malignancies such as liver, lung, and ovarian cancers, liver disease and infections, and benign breast conditions.
In some cases, a person with normal CA 15-3 levels may still have breast cancer, so it is crucial to interpret elevated CA 15-3 results in the context of clinical findings and other diagnostic tests.
Increasing levels of CA 15-3 may indicate that the cancer has spread to other areas of the body. Levels of CA 15-3 generally increase in line with the advancement of breast cancer, but about 25% to 30% of people with advanced breast cancer have tumors that do not release CA 15-3. Decreasing levels of CA 15-3 or levels that return to normal may indicate that treatment is working effectively.
It is essential to note that false-positive results can occur in people with benign conditions, suggesting that tumor markers may not always be accurate indicators of cancer. Biotin supplements may interfere with certain lab tests, and a person may need to wait at least 8 hours since their last dose before the sample is collected if they are taking more than 5 mg per day.
The normal range for CA 15-3 levels is 30 units or fewer per milliliter (U/ml). People do not need to prepare for a CA 15-3 test, but they should inform their doctor about any medications, supplements, or herbal remedies they are taking.
While CA 15-3 is primarily used to monitor metastatic breast cancer or detect its recurrence, its elevation is not specific to breast cancer alone and can be seen in these other malignancies and non-cancerous conditions. It is important to interpret elevated CA 15-3 results in the context of clinical findings and other diagnostic tests to ensure an accurate diagnosis.
References:
[1] Mayo Clinic. (2018). CA 15-3 blood test. Retrieved from https://www.mayoclinic.org/tests-procedures/ca-15-3-blood-test/about/pac-20385149
[3] National Cancer Institute. (2019). CA 15-3. Retrieved from https://www.cancer.gov/publications/dictionaries/cancer-terms/def/ca-15-3
The CA 15-3 test is used not only for breast cancer but also for other malignancies such as liver, lung, and ovarian cancers. Elevated CA 15-3 levels can indicate advancement or spread of breast cancer to other areas of the body. However, it is crucial to interpret CA 15-3 results in the context of clinical findings and other diagnostic tests to ensure an accurate diagnosis, as false-positives can occur in people with benign conditions.
