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ASCO Issues Guidelines on Using Biomarkers to Make Treatment Decisions in Women Diagnosed With Metastatic Disease

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The American Society of Clinical Oncology (ASCO) has put out new guidelines on using biomarkers to make decisions about systemic therapies to treat women diagnosed with metastatic breast cancer.

The guidelines were published online on July 21, 2015 by the Journal of Oncology Practice. Read the abstract of “Use of Biomarkers to Guide Decisions on Systemic Therapy for Women With Metastatic Breast Cancer: American Society of Clinical Oncology Clinical Practice Guideline.”

ASCO is a national organization of oncologists and other cancer care providers. ASCO guidelines give doctors recommendations for treatments and testing that are supported by much credible research and experience.

Biomarkers are certain genetic characteristics in cancer cells that can help predict how the cancer will respond to certain treatments. For example, HER2 status is a biomarker. If a cancer is HER2 positive, it’s very likely that the cancer will respond to anti-HER2 medicines. Other biomarkers include estrogen-receptor status, progesterone-receptor status, and BRCA1 and BRCA2 status.

Systemic treatments are treatments that involve the entire body. Treatments such as chemotherapy, hormonal therapy, and targeted therapies are systemic therapies.

Metastatic breast cancer is advanced-stage breast cancer. Metastatic breast cancer means the cancer has spread to parts of the body away from the breast area, such as the bones, liver, or lungs.

When a person is first diagnosed with breast cancer in the breast area, doctors do a biopsy and run a number of tests on the tissue removed to determine the characteristics of the cancer, including hormone-receptor and HER2 status. This information helps guide treatment decisions.

Still, if cancer is found in a place in the body away from the breast (meaning the cancer metastasized) while or shortly after the person was being treated for the primary cancer in the breast, it hasn’t been clear if the metastatic cancer should be biopsied to see if its characteristics are the same as the primary cancer’s characteristics.

In the past, it was assumed that the metastatic cancer was the exact same cancer in a new location. But research has shown that cancer cells are constantly changing. Studies have found that metastatic cancer can have very different characteristics than the primary cancer. For example, the primary cancer may be hormone-receptor-positive and the metastatic cancer may be hormone-receptor-negative. So they would require different treatments.

The new ASCO guidelines offer doctors advice on whether metastatic breast cancers should be biopsied, as well as whether biomarkers other than hormone-receptor and HER2 status should be considered when making systemic treatment choices.

The guidelines say:

  • People with newly diagnosed metastatic breast cancer should be offered a biopsy to confirm estrogen-receptor, progesterone-receptor, and HER2 status.
  • If the metastatic cancer has different hormone-receptor or HER2 status than the primary cancer and the person is still being treated for the primary cancer, doctors should tell the person that it’s not clear if results are better if treatment is based on the biomarkers in the primary cancer or the metastatic cancer. Still, the ASCO expert panel that developed the guidelines felt that doctors should base treatment on the characteristics of the metastatic cancer as long as the treatments aligned with the person’s choices.
  • Decisions about starting systemic treatment for metastatic breast cancer should be based on the hormone-receptor and HER2 status of the cancer, the doctor’s judgment, and the patient’s preferences. There isn’t any evidence showing that starting systemic treatment based on biomarkers beyond hormone-receptor or HER2 status improves outcomes.
  • For people already being treated with systemic therapies for metastatic breast cancer, there is no evidence that switching to a new treatment based on biomarkers beyond hormone-receptor and HER2 status improves outcomes, quality of life, or cost-effectiveness.
  • A cancer tumor can produce specific proteins in the blood that can serve as a biomarker. These circulating tumor markers can be measured with a simple blood test. The proteins CA 15-3 and CA 27.29 are circulating tumor markers for metastatic breast cancer. Levels of these two proteins may be used along with clinical evaluation of the cancer to decide if the cancer is responding to treatment. There isn’t enough evidence to recommend using CA 15-3 and CA 27.29 levels alone to decide if the cancer is responding to treatment.

If you’ve been diagnosed with metastatic breast cancer, you and your doctor will consider a number of factors when deciding on treatments, including:

  • the characteristics of the cancer
  • which treatments you’ve already had
  • your general health
  • where and how extensively the cancer has returned
  • your personal preferences

For more information, visit the Treatments for Metastatic Breast Cancer page.

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