Hormone receptor-positive

One of the first steps in understanding a breast cancer diagnosis is knowing whether the cancer cells have certain behaviors or characteristics that cause them to grow. Hormone receptor-positive, or HR-positive, breast cancer grows in response to the hormones estrogen and progesterone. These hormones occur naturally in the body and prompt cell action in different ways.

Role of hormones in the body

Our bodies naturally make hormones, including estrogen and progesterone.

Estrogen has multiple roles. It helps sex organs develop, makes pregnancy possible, strengthens bones, and more.

As you get older, the level of estrogen in your body changes.

• In premenopausal women who have periods, the ovaries make most of the body’s estrogen. Estrogen levels in premenopausal women are usually high.
• In perimenopause, the ovaries slow down and make less estrogen. But it is still possible to have menstrual periods, even when the ovaries are working more slowly. Periods may sometimes be irregular. This in-between time happens several years before menopause.
• In menopause, the ovaries gradually stop making estrogen. Periods become irregular and then stop altogether.
• Post-menopausal means a woman has not had any menstrual periods for 12 months in a row and blood work demonstrates hormonal levels are in post-menopausal range.

After menopause, the ovaries no longer make estradiol, the most active form of estrogen. But a woman’s body still makes estrone, another form of estrogen, after menopause. Estrone is made when an enzyme called aromatase converts the male sex hormone androstenedione — made in the adrenal glands, ovaries, and fat cells — into estrogen. In men, androstenedione is made in the testes.

The hormone progesterone is made in the ovaries and the adrenal glands. Progesterone regulates reproductive functions such as the menstrual cycle, and helps the uterine lining support a fertilized egg. In women who become pregnant, progesterone is made in the placenta, and it helps maintain pregnancy.

What are hormone receptors?

Hormone receptors are a type of protein found in or on cells. These proteins can attach to certain substances, including estrogen and progesterone. When they do, the estrogen and progesterone tell the cell to grow, multiply, or repair damage.

Normal breast cells need estrogen and progesterone receptors to grow. So do some breast cancer cells.

Hormone receptor-positive breast cancer can be defined as:

• Estrogen receptor-positive and progesterone receptor-negative (ER+/PR-). In ER+ breast cancer, the cancer cells have estrogen receptors, and estrogen tells the cells to grow or spread.
• Estrogen receptor-negative and progesterone receptor-positive (ER-/PR+). In PR+ breast cancer, the cancer cells have progesterone receptors, and progesterone tells the cells to grow or spread.
• Both estrogen receptor-positive and progesterone receptor-positive (ER+/PR+). In ER+/PR+ breast cancer, the cancer cells have both types of receptors, and both hormones tell the cells to grow or spread.

If breast cancer cells are negative for both the estrogen receptor and progesterone receptor, the breast cancer is called hormone receptor-negative.

Knowing the hormonal status of the breast cancer — whether estrogen or progesterone is involved in directing the cancer cells to grow — helps your doctors choose the best treatment for you:

• Estrogen receptor-positive and progesterone receptor-positive breast cancers can be treated with hormonal therapies as well as other cancer treatments if necessary.
• If the cancer cells are hormone receptor-negative, other features of the cancer will determine what treatments may be effective.

Testing for hormone receptor-positive breast cancer

After a breast cancer biopsy, the removed sample of breast tissue is sent to a lab for testing. If the tissue is confirmed to have cancer cells, the tests help your care team learn more about the cancer and how to treat it. Your doctor will share the test results with you in a document called a pathology report.

One test performed on breast cancer cells is called an immunohistochemical staining assay, or IHC test. This test checks the hormone receptor status of the cancer cells. IHC tests show whether the cancer cells have estrogen receptors, progesterone receptors, or both.

Questions to ask your doctor

The hormonal status of the breast cancer is an important part of determining which treatments will work best for you. It’s completely appropriate to ask your doctor how tests are performed, who is performing them, and what your results mean, if having that information is important to you.

Here are some questions that can help guide the conversation with your doctor.

Before testing:

• Will the results for my test be specific about whether there are receptors for estrogen and progesterone? If not, how can we get this information?
• When the results are ready, how can I get a copy?
• Will the results be included in my complete pathology report?
• What could the possible test results be, and what do they mean?
• Will you be going over my test results with me? If not, which team member will be?

After test results arrive:

• Based on my test results, what treatments do you recommend?
• Is there any reason I should have this testing done again?

How to manage a hormone receptor-positive breast cancer diagnosis

Several FDA-approved treatments available for hormone receptor-positive breast cancer are effective at reducing the risk of breast cancer recurrence. Because of this, you may hear people say that hormone receptor-positive breast cancer is the “best” breast cancer to have. We know hearing others say these kinds of things can be difficult or angering — having any kind of cancer is challenging. Remember that your experience with breast cancer is your own. It’s OK to feel overwhelmed, scared, depressed, and angry, because we all handle emotional and physical treatment side effects differently.

It's important after a cancer diagnosis to surround yourself with people you trust and who allow you space to experience your emotions as they come. Not everyone in your life will be able to do this, and that can feel isolating. Here are some strategies to help you navigate your emotions after diagnosis:

• Write your feelings a journal
• Talk to a trusted friend or family member
• Relieve stress through calming activities such as meditation, yoga, or other complementary therapies
• Ask your hospital social worker to recommend a therapist who specializes in cancer care

You can also visit these pages for more ways to feel supported, and to connect with others who’ve been diagnosed:

• Finding support
• Coping with breast cancer
• Breast cancer support groups

If you’d like to talk to an LBBC Helpline volunteer whose diagnosis matches your own, fill out our online form to be matched.

Treatment options

Treatments for hormone receptor-positive breast cancer may include hormonal therapy, radiation therapy, chemotherapy, or targeted therapy.

Hormonal therapy, also called endocrine or anti-estrogen therapy, only works in hormone receptor-positive cancers. Different hormonal therapies work in different ways. One way is to block the estrogen and progesterone that the cancer relies on to grow and survive. Another way is to decrease the amount of estrogen produced in the body. These treatments disrupt the growth signals sent by the hormone receptors to cancer cells.

Depending on the type, hormonal therapy works by:

• Blocking estrogen or progesterone receptors
• Reducing the amount of estrogen made in the body
• Lessening the number of hormone receptors on the cancer cells

When used as recommended, it can:

• Lower the risk of the cancer recurring (coming back)
• Reduce the risk of new breast cancers developing
• Improve survival

It's important to know that hormonal therapy is not the same as hormone replacement therapy (HRT), which is sometimes given after menopause to replace hormones no longer made by the ovaries. HRT helps relieve menopausal symptoms, such as vaginal dryness and hot flashes. If you have been diagnosed with hormone receptor-positive breast cancer, it is not safe for you to take systemic HRT (HRT taken as a pill, through a skin patch, or in other ways that affect the whole body). However, vaginal estrogen therapies that are local (focused on treating one specific area of the body) have not been shown to increase the risk of breast cancer recurrence. Always talk with your doctor about the safest way to manage menopausal symptoms.

There are many types of hormonal therapy for breast cancer. The two most common types are estrogen blockers and aromatase inhibitors.

• Estrogen blockers work by preventing estrogen from helping breast cancer cells to grow. There are two types of estrogen blockers, SERMs and SERDs, that work in slightly different ways to make this happen:
  • Selective estrogen-receptor response modulators (SERMs). SERMs work by blocking estrogen from attaching to cancer cells. When estrogen can’t attach, it is not able to tell the cancer to grow. The SERM tamoxifen is the standard hormonal therapy for premenopausal women. Common side effects include hot flashes and vaginal discharge, dryness, or irritation. Rare but serious side effects include endometrial (uterine) cancer and a slightly increased risk of blood clots that could lead to stroke. Learn more about tamoxifen.
  • Selective estrogen receptor downregulators (SERDs), also known as estrogen receptor antagonists (ERAs). These medicines attach to estrogen receptors and block estrogen from helping the cancer cells to grow. They can also cause the breakdown of the estrogen receptor, or a reduction in the number of receptors. SERDs are only available to people with metastatic breast cancer, and include fulvestrant (Faslodex) and elacestrant (Orserdu). The side effects of SERDs include hot flashes, joint pain, and constipation. Fulvestrant is given by intramuscular injection, and elacestrant is taken as a pill.
• Aromatase inhibitors (AIs) interfere with estrogen production by stopping the enzyme aromatase from converting the male androgen hormone to estrogen. This results in decreased estrogen in the body. In general, AIs are given to postmenopausal women. However, AIs may also be given to premenopausal women who have hormone receptor-positive breast cancer that has a high risk of recurrence. In order for premenopausal women to be able to take AIs, they are also given treatments that suppress the ovaries. These can include medicine, surgery, or radiation therapy. AIs include:
  • Anastrozole (Arimidex and generic)
  • Letrozole (Femara and generic)
  • Exemestane (Aromasin and generic)

Side effects of AIs include:

• Bone loss
• Joint pain and muscle aches
• Menopausal symptoms
• High cholesterol

AIs have a lower risk of causing blood clots and stroke than tamoxifen does.

If you have been diagnosed with hormone receptor-positive breast cancer, you and your doctor will decide on a hormonal therapy. It’s important to let your doctor know about your medical history, including any other health conditions you’ve had or currently have, and any medicines or supplements you are taking. Be sure to ask about the risks, benefits, and side effects of each type of hormonal therapy in order to make the best treatment decision for you.

Learn more about Types of hormonal therapy.

Triple-positive breast cancer

The same IHC test that shows the breast cancer’s hormone receptor status can also tell your doctor if the cancer cells have a too much of a protein called HER2 on their surface. Another type of test, called in situ hybridization (ISH), looks for extra copies of HER2 genes inside cancer cells. The most commonly used ISH test is the fluorescent in situ hybridization (FISH) test.

It’s possible to have hormone receptor-positive breast cancer that also tests positive for HER2 receptors. Some people refer to breast cancer that tests positive for all three receptors as triple positive. Triple-positive is not an official name for a diagnosis, but you may hear it used informally.

Knowing your HER2 status is important because there are treatments designed especially for HER2-positive breast cancers. If you have triple-positive breast cancer, your treatment will likely include medicines that target the HER2 receptors and medicines that target the hormone receptors. Learn more about HER2-positive breast cancer and treatments.

If IHC and FISH tests show that the cancer cells have none of the three receptors (ER, PR, and HER2), the breast cancer is called triple-negative breast cancer. Triple-negative breast cancers do not respond to hormonal therapies or anti-HER2 therapies. Learn more about triple-negative breast cancer and treatments.