The breast cancer treatment journey – something nearly one in eight women will experience sometime in their lifetime – can be overwhelming and filled with uncertainty. To hear “you have breast cancer,” or “your breast cancer is progressing” can be incredibly jarring. Often, one of the first things people want to know about their breast cancer is its stage, meaning how extensive the breast cancer is based on tumor size, its location and whether it has spread to nearby lymph nodes or other parts of the body.
While stage is certainly important in helping determine how to treat breast cancer, there are a number of other factors patients should consider with their healthcare team. One such consideration is their breast cancer type, which can be determined by the presence of certain proteins or other substances that can lead to the presence of cancer, also known as cancer biomarkers. These biomarkers can provide valuable information about the cancer, including how aggressive it is and whether it may help inform treatment options.
Here are five things to know about human epidermal growth factor receptor 2 (HER2), one of the commonly seen breast cancer biomarkers.
1. You too should think about HER2.
BRCA genes are the most well-known genes linked to breast cancer, and might be among the first things that come to your mind when you hear “breast cancer biomarker.” But if you receive a breast cancer diagnosis or learn your cancer has returned or is spreading, you should also think about HER2. HER2 is a protein found on the surface of all breast cells, and when an individual with breast cancer has higher-than-normal levels of the HER2 protein, among other factors, their cancer can be considered HER2-positive. This form of breast cancer, which accounts for about one in five cases of breast cancer in the US, tends to grow faster and is more likely to spread and come back compared to HER2-negative breast cancers.
2. There are a number of tests available to detect the presence of HER2.
Testing for HER2 is a routine process that can help patients receive an appropriate diagnosis and treatment plan. It’s important to speak with your physician regarding available testing options and what the results may mean for you.
Two of the most common tests to find out if a person’s breast cancer is HER2-positive are:
- IHC (Immunohistochemistry): IHC test works by identifying the level of HER2 proteins on the surface of cells. In breast cancer, a score of 3+ means that the cancer has a lot of this protein and is considered “HER2-positive,” while a score of 0 or 1+ means that the cancer has low levels or no detected levels of HER2, or “HER2-negative.” A score of 2+ means that the levels are in-between and other tests, such as ISH, will be performed.
- ISH (In Situ Hybridization): ISH test is used to find specific pieces of a cell’s DNA. Based on the signal, can inform whether the cell has abnormalities such as extra or fewer than expected copies. A tissue sample with abnormalities will be scored ISH-positive.
3. Your HER2 status can change.
It is important to note that HER2 status can change over time. The change may happen due to certain treatments, or due to cells evolving as the cancer progresses. If your breast cancer returns or spreads to other organs, you and your doctor may have a discussion to see if it would make sense to do a biopsy to retest your tissue.
4. Great strides have been made in research and treatments for HER2-positive breast cancer.
Thanks to ongoing research, doctors have a much better understanding of various types of metastatic breast cancer, and today there are a number of treatments available or in development, specifically for HER2-positive metastatic breast cancer. Historically, patients had chemotherapy and hormonal therapy as treatment options. Today, there are also targeted treatment options available to patients living with this disease.
5. It starts with a conversation.
It is important to speak with your healthcare team about biomarker testing and from there, develop a plan together that best suits your diagnosis and your needs. Breast cancer management is not a one-size-fits-all approach. Having an open dialogue with your healthcare team about the characteristics of your cancer, including its subtype, can help empower you to chart your journey forward.
For more information, you can also visit Beyond Pink for helpful resources and support on navigating your journey with metastatic breast cancer.
 American Cancer Society. How Common Is Breast Cancer? May 2021. Accessed October 2021.
 National Breast Cancer Foundation. Breast Cancer Stages. Accessed October 2021.
 National Cancer Institute. Tumor Markers. May 2021. Accessed October 2021.
 Ahn S, et al. J Pathol Transl Med. 2019; 54(1): 34–44.
 Komen.org. BRCA1 and BRCA2. June 2021. Accessed October 2021.
 American Cancer Society. Breast Cancer HER2 Status. September 2019. Accessed October 2021.
 Breastcancer.org. Breast Cancer’s Hormone Receptor and HER2 Status Can Change After Diagnosis. June 2012. Accessed October 2021.