A biomarker is a sign of disease or abnormal function that can be measured in your blood, tissue, or bodily fluid. In cancer, biomarkers are often used to help choose the best treatment for you. These biomarkers can be proteins, genes, or gene mutations.
Biomarker testing helps your doctor match targeted therapy drugs to the specific subtype of cancer you have. In biomarker testing, a sample of your cancer is collected from your blood, bodily fluids, or tissue taken during surgery or biopsy. Your sample is sent to a lab. The test looks for biomarkers in your cancer sample. The test results can be used to help guide your treatment options. Biomarkers tell your doctor about the subtype of the cancer in your body.
Biomarkers are often referred to by a 3- or 4-letter abbreviation. Examples of biomarkers are HER2 in breast cancer or EGFR in lung cancer. A positive test (HER2+ or EGFR+) means the cancer’s genes have that mutation.
Your doctor may call this kind of testing biomarker testing, genomic testing, molecular profiling, tumor marker testing, mutation testing, or molecular testing. These are all the same kinds of tests. Their results help your doctor know what treatments may work best for you.
To learn more about targeted therapy and precision medicine, visit our Precision Medicine page.