Tumor Marker for Breast Cancer

Tumor marker refers to a substance that is present in an individual’s urine, blood or the tumor itself. Tumor marker is secreted either by the body or by the tumor in the presence of cancer. You may be recommended to have tumor markers tested at various stages of cancer to aid in the diagnosis and treatment. In combination with other medical tests, a test done to measure tumor marker is quite helpful in providing useful information regarding the cancer and its treatment. For those who are concerned, it helps to know what these tumor markers mean and which tumor marker test to choose for a particular breast cancer.

How Can We Use Tumor Marker for Breast Cancer?

Tumor markers for breast cancer are used in the following ways:

  • To help in the planning of treatment in one of the following scenarios: to determine whether the cancer in a patient has a favorable prognosis or not (what is the behavior of the cancer and the patient’s recovery chances) and whether the cancer will require additional treatment or not; to predict the success of a specific treatment in a patient.
  • To help in keeping a check on how a patient is recovering over time.
  • To help in determining the risk of developing cancer.
  • To help in detecting cancer in its early stage when there are no signs or symptoms of cancer present.

What Are Common Tumor Markers for Breast Cancer?

The common tumor markers used for breast cancer are: ER and PR, HER2, CA 15-3, CA 27.29 and CEA, uPA, PAI-1 and oncotype DX.

1. PR and ER (Progesterone receptor and Estrogen receptor)

ER and/or PR positive breast cancer cells require estrogen and/or progesterone for their growth. ER and PR testing is done to determine whether the cancer requires hormone therapy such as tamoxifen (Nolvadex) for treatment.

2. HER2 (Human epidermal growth factor receptor 2)

This is a protein that is present in large quantities in almost 20-25% of breast cancer cases. To stop the growth of cancer cells anti-HER2 treatment is given which blocks HER2. HER2 tests help the physician to determine whether the cancer requires anti-HER2 treatment such as trastuzumab (Herceptin) or not.

3. CA 15-3 (Cancer antigen 15-3), CA 27.29 (cancer antigen 27.29) and CEA (carcinoembryonic antigen)

These are tumor markers that are present in almost 50-90% of patients suffering from metastatic breast cancer. However, high levels may indicate other condition apart from cancer. These tests are also monitored to determine an early recurrence after initial treatment of the primary tumor. It is also done to determine the success of cancer treatment.

4. uPA (Urokinase plasminogen activator) and PAI-1 (plasminogen activator inhibitor)

These tumor markers are present in high amounts in aggressive forms of cancer or cancers which grow very fast. These tests require specific methods to store and save the tissue for testing and are not as common as other tumor marker tests. Test for these tumor markers is done to determine whether chemotherapy is required after surgery in patients having node-negative (meaning having no cancer found in lymph nodes) breast cancer.

5. Oncotype DX

This test is the measurement of multiple genes at one time to determine the risk of recurrence of breast cancer in patients who have early-stage, ER positive and node-negative breast cancer. Patients who have a low recurrence score usually require treatment with only hormone therapy and they can avoid chemotherapy.

What does Tumor Marker Tests for Different Breast Cancer Mean to You?

Tests for tumor markers help in both planning and monitoring cancer treatment and in determining the prognosis of cancer. The tumor markers mentioned above are helpful in predicting the response to particular therapy and/or also in finding the best treatment for your cancer.

What Questions Should You Ask Your Doctor?

You should ask your doctor the following questions to know more about tumor markers:

  • What tumor markers tests are recommended by your doctor? Which tests have already been done?
  • What is the method to perform these tests?
  • How often will these tests be performed?
  • Do the tests need to be done in a laboratory that is accredited by the College of American Pathologists (CAP)?
  • What are the test results and how will they affect your treatment?
  • What medicines or health conditions may interfere with these tests?

What Are Recommended Tumor Marker Tests for Different Breast Cancer?

Type of Breast Cancer

Recommended Tumor Marker Tests

Newly diagnosed ductal carcinoma in situ (DCIS)

No tumor marker tests are recommended as DCIS implies that the cancer is confined to the ducts of the breast and is non-invasive in nature.

Newly diagnosed invasive breast cancer

  • PR and ER tests to aid in the prediction of response to hormone therapy post surgery.
  • HER2 test to aid in the prediction of response to trastuzumab and other anti-HER2 therapies and certain forms of chemotherapy.

Node-negative breast cancer

uPA and PAI-1 tests to determine the prognosis of cancer. Patients with negative uPA and PAI-1 have excellent prognosis and may not require chemotherapy.

Node-negative breast cancer that is ER positive and/or PR positive

Oncotype DX test to identify the patients who will require only tamoxifen and can avoid chemotherapy.

Metastatic breast cancer

  • ER and PR tests to determine the response to hormone therapy.
  • HER2 test to determine the response to trastuzumab and other anti-HER2 treatments.
  • CA 15-3 and CA 27.29 to monitor treatment; these tests should be used in combination with health history of patient, a complete physical examination, and diagnostic imaging tests including x-ray, CT scan and/or MRI.
  • CEA to monitor treatment; this test should also be used in combination with health history of patient, a complete physical examination and diagnostic imaging tests.

Recurrent breast cancer

HER2 test to determine the response to trastuzumab and other anti-HER2 treatments and indicate which specific chemotherapy need to be used.

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