Demystifying Breast Cancer Receptors
Key takeaways:
Receptors are molecules that sit on the surface of a cell, signaling to the cell to turn certain functions on and off.
Some breast cancer cells have receptors on the cell surface that can increase cancer growth if the receptors are activated by estrogen or other molecules.
It is important to test breast cancer cells for these receptors because testing helps determine your treatment options.
When you’re diagnosed with breast cancer, part of the diagnostic process is to determine if your cancer cells have specific receptors. The receptor status of breast cancer is important because it affects which treatments will work the best. It can also be one of the factors that helps determine the cancer stage.
Understanding receptor terminology is important, so we will explain the different types of receptors, how they work, and how they can impact your treatment plan.
What do cell receptors do?
Receptors are located on the outer surface of a cell, and they behave like little light switches for the cell. Those receptors can be activated, or turned on, when they bind to certain hormones or molecules in the body. This activation process tells the cancer cell to grow and multiply.
Breast cancer can have a few specific receptors that do this. After you have a biopsy of cancer cells, those cells can be tested for the presence of these receptors.
What are the different types of breast cancer receptors?
Every case of breast cancer can either be positive or negative for three types of receptors. Positive means the receptor is present in large quantities. Negative means the receptor is absent, or is only present in smaller amounts. The three types of receptors are:
The estrogen receptor (ER) and progesterone receptor (PR): The ER and PR receptors promote cancer growth when they bind to estrogen. They are referred to as hormone receptors.
The human epidermal growth factor receptor 2 (HER2): This one is referred to as a molecular receptor. All breast cells contain HER2 on their surface, but some breast cancer cells have this receptor in particularly large amounts. This receptor is activated by certain proteins rather than hormones.
Combination receptors: Breast cancers can have any combination of the receptors listed above or none at all. If you’ve ever heard the term triple-negative breast cancer, this means a tumor does not have ER or PR receptors, and it has low levels of the HER2 receptor.
Why are breast cancer receptors important?
The receptor status of a cancer is important for two main reasons:
It can impact the staging process.
It can help to determine which treatment options will work best.
Breast cancer stages
Breast cancer is staged 0 through 4, depending on how advanced it is. One of the most important factors in staging is determining how far a cancer has spread. If the cancer spreads to surrounding tissues, lymph nodes, or distant parts of the body it tends to lead to a higher stage. But other factors are also taken into account, like receptor status.
For example, triple negative breast cancer is usually put into a higher stage than breast cancer that is receptor-positive because it tends to be more aggressive and more likely to spread than other types of breast cancer.
Breast cancer treatments
There are certain breast cancer treatments that are specifically designed to block the receptors, which can help prevent the cancer cells from multiplying. But these treatments will only work on cancers that are positive for these receptors.
Two categories of treatment work at the level of the receptor:
Hormone therapy
Targeted therapy
Hormone therapy is a treatment option for breast cancer that is ER or PR positive. These medications either block the estrogen signal for these receptors or lower the amount of estrogen in the blood. Examples include receptor blockers like tamoxifen (Nolvadex, Soltamox), or aromatase inhibitors like arimidex (Anastrozole).
There are other treatments for hormone receptor-positive breast cancer as well. One type of treatment, called CDK 4/6 inhibitors, can treat breast cancer that is hormone-receptor positive. These treatments don’t affect hormones but instead interfere with the signals for cell growth inside the cells.
Targeted therapy is an option for HER2-positive breast cancer. These treatments block the HER2 receptor so the cancer cells don’t get the signal to grow. Traztuzumab (Herceptin) is a common therapy for HER2-positive breast cancer.
Both hormone therapy and targeted therapy are often given along with chemotherapy. Some people might also take hormone therapy for several years after treatment to prevent the cancer from recurring.
The bottom line
Breast cancer comes with a lot of terminology that might be new to you. And the world of cell receptors certainly contributes to that confusing glossary of terms. It is helpful to understand what breast cancer receptors are because they may play a role in the staging and treatment processes.
Make sure your healthcare provider answers all your questions about breast cancer. By understanding every part of the process, you can ease some of the uncertainty — and anxiety — that come with a cancer diagnosis.
Why trust our experts?
References
American Cancer Society. (2021). Breast cancer HER2 status.
American Cancer Society. (2021). Breast cancer hormone receptor status.
American Cancer Society. (2021). Hormone therapy for breast cancer.
American Cancer Society. (2021). Targeted drug therapy for breast cancer.
American Cancer Society. (2021). Triple-negative breast cancer.
Breastcancer.org. (2021). Breast cancer stages.
Breastcancer.org. (2021). Triple-negative breast cancer.
Conner, K. (2021). What are CDK4/6 inhibitors? Breastcancer.org.
