Breast Cancer Tumor Marker Tests

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Tumor markers are substances that show up in your blood, urine, or tumor. These are hormones, proteins, or parts of proteins that are made by the tumor or by your body, in response to the tumor or particular benign conditions. Some tumor markers are specific to one type of cancer and some are for general oncology use.

Note that estrogen (ER) and progesterone receptors (PR) and human epidural growth factor 2 (HER2/neu) are not tumor marker tests, but are important in making decisions about treatment.

Similarly, mammogramsultrasound, and breast MRIs are imaging tools that can screen for breast cancer. These tests are highly sensitive and specific enough to detect breast cancer before there are symptoms. A tumor marker test alone does not provide enough information to screen for breast cancer.

Tests

Tumor markers commonly used by oncologists to monitor breast cancer are:

Uses

Oncologists use tumor marker tests to detect, diagnose, and monitor cancer. These test results are used together with other data, such as biopsy results, to get a clear picture of the stage of your cancer, what type of treatment will be most effective, and to measure your progress during treatment.

You may have a tumor marker test before starting treatment to get a baseline level. This score will be used to compare with later tumor marker tests.

Ask for a copy of your tumor marker tests and keep these with your health records.

Results

Your test levels will show how well your treatment is working. If your tumor marker levels decrease, that is a good sign that the cancer is responding to the therapy. An increased level indicates that the cancer is resisting the treatment and a change may be required.

Rising levels on your test results can be, but are not always, worrisome. Although changes in tumor marker levels may give you cause for alarm, other non-cancerous diseases can cause test results to vary.

Conditions in the lab that processes your test may also throw off the results. Always talk to your oncologist about your test results and keep asking questions until you understand how these results will impact your prognosis and treatment plan.

After you have finished treatment, another tumor marker test may be done to check for any return of the cancer. During your follow-up visits after initial treatment, tumor marker tests may be done to monitor for recurrence.

Sources

American Society of Clinical Oncology (ASCO). Patient Guide. Tumor Markers for Breast Cancer. PDF file. October 2007.

American Cancer Society. Tumor Markers. What Are Tumor Markers?

National Cancer Institute. Fact Sheet. Tumor Markers: Questions and Answers.

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