What is Cancer Antigen 15.3 test?

Cancer antigen 15.3 (CA 15.3) test is performed to measure the amount of CA 15.3 protein in blood. This protein is produced at normal levels by healthy breast cells. High levels of CA 15.3 are primarily present in the body due to breast cancer; therefore, they are called tumour markers. Tumour markers are proteins that provide information about cancer. This test also helps detect the recurrence of breast cancer.

  1. Why is CA 15.3 test performed?
  2. How do you prepare for CA 15.3 test?
  3. How is CA 15.3 test performed?
  4. CA 15.3 test results and normal range

Although CA 15.3 test is primarily used to diagnose breast cancer, patients with the following conditions might also have elevated CA 15.3 levels:

This test is not used for screening in breast cancer, as it is not specific. Doctors generally recommend this test to measure the effectiveness of cancer treatment in women with a history of breast cancer or to check for the recurrence or growth of cancer in women with breast cancer. Other diagnostic tests, including CA 27.29 test, might be performed along with CA 15.3 test to confirm the results.

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There are no special preparations required for this test. However, it is important to inform your health care provider about prescription and nonprescription medications, herbs and supplements that you may be taking before undergoing the test. They should also be informed about any addictions or drugs, if you are taking any.

A blood sample is collected from a vein on the back of the hand or on an arm using a needle. No risks are involved with this test. However, people might feel a slight pain at the site where the needle was injected.

Some individuals may feel lightheaded after the blood sample is withdrawn. Rarely this test may lead to bruising, soreness or infection. In the latter case, it is important to talk to your doctor to avoid health conditions.

(Consult physician online)

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Normal results: CA 15.3 levels below or equal to 30 units per millilitre (U/mL) are considered to be normal and indicate an absence of metastatic (cancer that has spread) or localised (cancer in the particular organ) breast cancer

However, normal levels may also indicate the following:

  • A rare case (found in about 20% to 25% of people) in which advanced cancers do not release 15.3 protein
  • A very early stage of the disease

Abnormal results: Mild to moderate levels of CA 15.3 indicate the presence of the following conditions:

  • Colon, lung, prostate, pancreatic or ovarian cancer
  • Hepatitis
  • Benign problems in the breast
  • Cirrhosis

The highest levels of CA 15.3 indicate that cancer has spread to other organs, such as liver and bones. A constant rise in  CA 15.3 levels indicates cancer recurrence or that the treatment provided for cancer is ineffective.

Elevated CA 15.3 levels are observed in about 80% of women with metastatic cancer and fewer than 50% of women with a small tumour in their breast.

A temporary elevation in CA 15.3 levels occurs in some cases of noncancerous diseases, which stabilises over time.

A constant reduction in CA 15.3 levels indicates that the progression of cancer has reduced.

Many factors including noncancerous diseases of liver, breast and ovary, affect test results. So, it is important to check in with a doctor for a correct diagnosis of the condition.

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. This information is purely from an educational perspective and is in no way a substitute for medical advice from a qualified doctor.

References

  1. University of Rochester Medical Center [Internet]. Rochester (NY): University of Rochester Medical Center; c2017. Health Encyclopedia: CA 15-3
  2. National Cancer Institute [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; Tumor Markers
  3. Chourin S, Georgescu D, Gray C, et al. Value of CA 15-3 determination in the initial management of breast cancer patients . Annals of Oncology. 2009:20(5):962-964.
  4. Pagana, Kathleen D., Pagana, Timothy J., and Pagana, Theresa N. (© 2015). Mosby's Diagnostic and Laboratory Test Reference.. 12th Edition: Mosby, Inc., Saint Louis, MO. Pp 196.
  5. Graham LJ, Shupe MP, Schneble ED, et al. Current Approaches and Challenges in Monitoring Treatment Responses in Breast Cancer. . Journal of Cancer. 2014; 5(1): 58-68. Published online 2014 Jan 5. doi: 10.7150/jca.7047
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