Biomarkers are molecules in your body that can be measured to give you information about your health. They play a big role in determining your breast cancer care. Read more to find out the 6 things you may not know about breast cancer biomarkers.
Biomarkers are some of what’s used to give information about your prognosis, test if your treatment is working and to indicate the best treatments for your breast cancer. Everyone diagnosed with breast cancer has their tumor tested for three key biomarkers: estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2). These breast cancer biomarkers are part of breast cancer staging and tell your oncologist if your breast cancer is hormone receptor-positive (about 70-80% of all breast cancers), HER2-positive (about 10-20% of breast cancers), or triple negative (about 15-20% of breast cancers). Each of these breast cancers have different treatments and prognoses. However, even more biomarkers are now used to further individualize a person’s breast cancer care.
Here are 6 things you may not know about breast cancer biomarkers:
- You can have any combination of the three main biomarkers ER, PR and HER2. You can be positive for all the biomarkers or any single biomarker. If your tumor tests positive for estrogen receptor and HER2, you’ll receive treatments designed for hormone receptor-positive and HER2-positive breast cancer. You can find your hormone receptor and HER2 status on your pathology report that your doctor reviews with you.
- There are treatments that target ER and HER2, but not PR. Hormone receptor-positive breast cancers are treated with hormone therapy, which targets the estrogen receptor. HER2-positive breast cancers are treated with HER2-targeting drugs. PR is used as a substitute marker for ER. If PR can be found in the tumor but ER can’t, doctors assume the estrogen receptor is active and treat the tumor with hormone therapy.
- Your biomarkers can change over time. Breast cancer treatments are good at killing breast cancer cells, but sometimes a small number of cells don’t die and they go undetected. For some unknown reason, the cancer cells grow again, which leads to breast cancer recurrence. If you have a recurrence, your breast cancer will be staged and tested for the three main biomarkers. These may have changed since your first diagnosis, so it’s important to ask your doctor about your cancer’s biomarkers at this time.
- You can have tumors with different biomarkers at the same time. If you have more than one tumor, it’s possible they may have different biomarkers. Doctors will sometimes biopsy multiple tumors to determine the best treatment plan.
- Biomarkers can be measured from your tumor or your blood. Some biomarkers are best measured using a sample from your tumor, known as a biopsy. Other biomarkers can be measured in your blood, which is known as a liquid biopsy. Currently, liquid biopsies are only used for testing biomarkers in metastatic breast cancer.
- Researchers are constantly looking for new biomarkers. The field of biomarkers and drug development is rapidly expanding, and more biomarkers have become part of routine testing. For example, PD-L1 is now tested for routinely in people with metastatic triple negative breast cancer to determine if they benefit from immunotherapy. Researchers look for biomarkers to identify the people that benefit the most from new treatments so that those who don’t benefit can avoid unnecessary side effects.
If you’re facing a breast cancer diagnosis and not sure where to begin, you’ve come to the right place. Our Know More series will continue to help educate you and arm you with the tools you’ll need to feel empowered to advocate for yourself through your experience.
Read More:
Downloadable Resource: Guide to Breast Cancer Biomarkers
Watch & Hear More:
Real Pink Podcast: How Biomarkers, Genetics, and Genomics Help Guide Breast Cancer Treatment
Former Komen Chief Scientific Advisor George Sledge Explains Liquid Biopsies
What Information Can a Biopsy Tell?
More Actions You Can Take:
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Join ShareForCures®. ShareForCures® is Komen’s Breast Cancer Research Registry that will be answering some of the most pressing questions in breast cancer. Anyone diagnosed with breast cancer over age 18 in the U.S. is eligible to participate.
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