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Updated on December 6, 2024
When deciding how to treat breast cancer, a cancer care team will want to learn as much as possible about the cancer and how the cancerous cells are behaving in the body. Two important pieces of information are hormone receptor (HR) status and HER2 status.
Learn what these terms mean and how this information can guide treatment decisions for the most common subtype of breast cancer—HR-positive/HER2-negative breast cancer.
What are hormone receptors?
Hormone receptors are proteins that attach to hormones. These are sometimes found on the surface of cancer cells or inside cancer cells. Hormones will stick to these receptors as they move through the body and encounter cancer cells, which can then use the hormones to fuel growth and multiplication.
Specific hormone receptors attach to specific hormones. The two hormone receptors involved in some breast cancers are estrogen receptors (ER) and progesterone receptors (PR). Breast cancer cells that have ER, PR, or both are categorized as hormone receptor-positive, or HR-positive.
What is HER2?
Human epidermal growth factor receptor 2 (HER2) is another type of receptor protein that controls how cells grow and divide. Some breast cancer cells have extra copies of the genes that control the production of HER2. These cells will have greater-than-normal amounts of HER2, which helps the cancerous cells multiply and spread.
Cancers that have large amounts of HER2 are categorized as HER2-positive (and cancers that do not have large amounts of HER2 are categorized as HER2-negative). In addition to breast cancers, HER2 status is an important factor to consider in the treatment of other types of cancer, including ovarian cancer, endometrial cancer, and cancers of the GI tract, bladder, and lungs.
Breast cancer subtypes
Breast cancers can be grouped into four different subtypes based on HR status and HER2 status:
- HR-positive/HER2-negative
- HR-negative/HER2-negative (called triple-negative breast cancer)
- HR-positive/HER2-positive (called triple positive breast cancer)
- HR-negative/HER2-positive
Hormone receptors and HER2 can be targeted by certain anti-cancer medications. Knowing HR status and HER2 status helps a cancer care team decide what medications are likely to be effective against the cancer—and what medications are less likely to be effective.
Treatment for HR-positive/HER2-negative breast cancer
The most common subtype of breast cancer is HR-positive/HER2-negative. Treatment for this subtype often includes hormone therapy, also called endocrine therapy.
HR-positive breast cancers use the hormones estrogen and/or progesterone to fuel their growth. Hormone therapy blocks cancer cells from using these hormones or shuts down the body’s ability to produce these hormones. This will help stop or slow the growth and spread of the cancer.
Hormone therapy can involve medications to suppress or interfere with hormone production. Or it can involve surgical procedures or radiation therapy to stop hormone production by the ovaries.
There are also a number of targeted therapy drugs for HR-positive/HER2-negative breast cancers. Targeted therapy drugs work by targeting specific proteins found on cancer cells.
Treatment can also include surgery, radiation therapy, and chemotherapy.
Your best source of information
HR status and HER2 status are not the only factors that will be considered when making treatment decisions about breast cancer. A healthcare team will also consider the stage of the cancer, the grade (how abnormal the cancer cells appear compared to healthy cells), the overall health of the person being treated, the person’s menopausal status, and their preferences for treatment.
It’s important to remember that every case of breast cancer is different, and every person’s treatment plan will be a bit different. If you have questions about any aspect of a diagnosis of breast cancer or treatment options for breast cancer, your best source of information will be your healthcare providers.
