Cancer is one of the most dangerous diseases on our planet, and along with each of its many forms, breast cancer is regarded as one of the most ominous. The disorder has consequences not only on a physical level but often imposes a sociocultural stigma, as many women do not feel comfortable disclosing their diagnosis or looking for timely treatment. Breast cancer is the most frequently occurring cancer among women and the 2nd leading cause of cancer related death among women in the United States.
Breast cancer is confusing because it is not just one disorder, it is comprised of several subtypes, each of which behaves differently and requires different treatment options. Understanding the difference between breast cancer subtypes is critical for early identification, successful treatment, and potentially improved survival. In this blog we will learn about the hormone-driven breast cancers (i.e. ER/PR-positive subtypes), and what they are, their sources of importance, and how they are managed.
What are the Different Types of Breast Cancer?
Breast cancer is not just one disease but a collection of diseases that grow, spread and are treated differently. These differences are often caused by the molecular subtype of breast cancer based on particular markers and genes contained in the tumor cells. It is important to understand the various subtypes of breast cancer to create the most effective treatment plan.
- Luminal Breast Cancer
This is the most common type, accounting for 60–70% of all cases. It has high estrogen receptor expression and no HER2 overexpression.
- Luminal A: Grows slowly, is lower grade, and has a better prognosis.
- Luminal B: It is more aggressive and shows higher cell‑growth activity.
- HER2‑Positive Breast Cancer
This subtype represents 12–20% of cases. Tumors overexpress the HER2 protein, which promotes rapid growth, but they often respond well to targeted therapy.
- Basal-Like Breast Cancer
This type of cancer represents about 15% of invasive breast cancers. Moreover, they are large high-grade tumors at diagnosis, and they also have a higher chance of recurrence.
- Triple-Negative Breast Cancer (TNBC)
This type is defined by a lack of expression of ER, PR, and HER2. Triple-negative breast cancer tumors are aggressive, more difficult to treat and have fewer options for targeted therapy.
Understanding ER/PR-Positive Subtype Breast Cancer
Breast cancers can act very differently based on what drives their growth. One of the most common and generally easily treated types is hormone-driven breast cancer, which is also known as ER/PR-positive breast cancer. These types of cancers use the natural hormones in the body, estrogen and/or progesterone, to grow and divide. Identifying whether a tumor is hormone driven is a vital part of diagnosis because it changes how the cancer is treated, as well as prognosis.
What is Hormone-driven (ER/PR-Positive) Breast Cancer?
Hormone-driven breast cancers have tumor cells with estrogen (ER) and/or progesterone (PR) receptors. These receptors are like “docking stations” for hormones, which attach and send the growth signals that lead to the proliferation of the cancer cells. This subtype is responsible for 70-80% of all breast cancers, making it the most common type around the world.
What are Estrogen and Progesterone Receptors?
A breast tumor is considered hormone receptor-positive if at least 1% of the cells test positive for ER or PR with immunohistochemistry (IHC) testing. Knowing this receptor status is important because it will influence targeted treatment options and provide knowledge on how the cancer may behave in the future.
- Estrogen receptors (ER): Proteins located either on or within breast cancer cells that combine with the hormone estrogen. When estrogen combines with the ER, it can stimulate the growth of a cancer cell.
- Progesterone receptors (PR): Similar proteins that combine with progesterone and it can also stimulate the growth of the cancer cell.
Treatment Options for ER/PR-Positive Breast Cancer
The objective of treatment is to stop the hormones causing the tumor to grow and then to treat the cancer or to remove the cancer. There are several treatment choices based on the stage of the cancer, your health, and your choice. Here is the information on treatment options:
| Treatment Options | How it Works | When it is Used |
| Surgery | Removes the tumor with a lumpectomy or mastectomy. | Early-stage cancer or localized cancer. |
| Radiation therapy | Uses high-energy rays to target cancer cells to reduce the chances of recurrence. | After a lumpectomy or, in some cases, a mastectomy. |
| Endocrine (hormone) therapy | Blocks or lowers estrogen from the body which slows or stops the tumors growing. | All stages of ER/PR-positive cancer, generally between 5-10 years. |
| Targeted therapy | Blocks certain pathways for growth (e.g., CDK4/6, PI3K). | Advanced or metastatic use in combination with hormone therapy. |
| Chemotherapy | Destroys rapidly dividing cells and cancer cells all over the body. | High-risk, aggressive, or advanced cancers. |
Empowering Women Through Awareness and Action
ER/PR-positive breast cancer is the most common type of breast cancer and is very treatable when caught early. Knowing how it works as a hormone-dependent cancer will help familiarize each woman with the treatment options available to her and improve quality of life.
Your health is in your hands, get screened for breast cancer regularly, know the signs, and take action if you notice something has changed.
