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What are Biomarkers?

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Get tested for biomarker expression

Not everyone benefits from the same type of cancer treatment. Cancer is a complex disease with over 71 different types and people with the same type of cancer can have significantly different cancers at the cellular level.1 Biomarkers are biological molecules, found in blood, other body fluids, or tissues, that are a sign of a normal or abnormal process or of a condition or disease.2 A biomarker may be measured by a diagnostic test to predict if the body will respond to a treatment for a disease, such as cancer. If the test shows that levels or the existence of a certain biomarker is different than what is typically seen in normal tissues, it may mean the cancer is dependent on the change in that biomarker and may react differently.

Examples of biomarkers include:

  • ER/PR in breast cancer
  • HER2 in breast cancer
  • KRAS in colorectal cancer
  • EGFR mutations in non-small cell lung cancer
  • BRAF in melanoma
  • HER2 in stomach cancer

How do I know if targeted treatments are right for me?

Therapy to directly target cancer cells

Biomarkers can tell doctors who may benefit from targeted medicines. Targeted medicines for treating some cancers have helped improve patient outcomes. These treatments may target certain molecules in cancer cells that are necessary for growth and survival of a tumor. They may work in a variety of ways, including inhibiting receptors that send growth and survival signals into cells or engaging the body's immune system to fight cancer cells. Depending on the type and molecular size of the drug, it may be administered as a pill or intravenously.

Targeted medicines represent a personalized way to treat disease. Scientists continue to research how cancer cells work in order to develop new ways to test for biomarkers and new targeted medicines.

If you test positive for a biomarker, you may be eligible for treatment with a targeted treatment. Ask your healthcare team for more information.


  1. Learn about cancer. American Cancer Society Web site. Accessed September 5, 2012.
  2. NCI Dictionary of Cancer Terms. National Cancer Institute Web site. Accessed September 5, 2012.