If a person has hormone receptor-positive breast cancer, it means that their breast cancer cells have estrogen receptors (ERs), progesterone receptors (PRs), or both.

Hormone receptor-positive breast cancer can respond well to different treatments. These may block or destroy the cells’ hormone receptors. Or they may reduce hormone levels in the body. The aim of both these approaches is to prevent the growth of cancer cells.

Below, we describe the different types of breast cancer and the roles that hormone receptors play.

We then turn to breast cancer that is ER-positive. We look at its symptoms, diagnosis, and treatment, as well as the outlook.

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When they diagnose breast cancer, a doctor also establishes its type. This involves an immunohistochemistry test to see whether the breast cancer cells contain hormone receptors that may respond to certain treatments.

The results of the immunohistochemistry test may indicate that a person has:

  • Hormone receptor-positive breast cancer: The breast cancer cells have ERs, PRs, or both. The cancer may respond favorably to medications that lower hormone levels or block hormone receptors.
  • Hormone receptor-negative breast cancer: The breast cancer cells have no ERs or PRs and will not respond to hormone therapy medications.
  • Triple-negative breast cancer: The breast cancer cells have no ERs or PRs, and they do not make any or too much of a protein called HER2. This means that the cancer will not respond to hormone therapy or medications that target HER2. Chemotherapy may be a viable treatment option.
  • Triple-positive breast cancer: The cancer cells have ERs and PRs, and they also make HER2. The cancer may respond favorably to hormone therapy medications and drugs that target HER2.
  • HER2-positive breast cancer: The breast cancer cells make HER2, but they may have no ERs or PRs.

As the American Cancer Society (ACS) notes, medical professionals also classify breast cancer by considering whether and how far the cancer has spread.

They may refer to breast cancer as “in situ” or “invasive.” The first term refers to precancerous cells that have not grown into the surrounding breast tissue.

Invasive cancer, on the other hand, has spread into the surrounding tissue. The most common types of invasive breast cancer are invasive ductal carcinoma and invasive lobular carcinoma.

When they determine the type of cancer, doctors also look at the types of cells involved. Breast cancer may be ductal, in which case it starts forming in the milk ducts. Or it may be lobular, in which case it starts forming in the glands that can produce milk.

Less commonly, other cell types may be involved. A person may, for example, have:

  • Paget’s disease of the breast: This can affect the skin of the nipple and areola.
  • Angiosarcoma: This type of cancer begins in cells that line the blood vessels or lymph vessels.
  • Phyllodes tumor: This type of tumor may be noncancerous, and it starts forming in the connective tissues of the breast.

Breast cancer cells may contain receptors for estrogen, progesterone, or both. In this case, the cancer is hormone receptor-positive. ERs respond to the hormone estrogen, while PRs respond to the hormone progesterone. When a hormone attaches to its receptor, it stimulates the cell to grow.

Someone with hormone receptor-positive breast cancer may benefit from medications that prevent estrogen or progesterone from attaching to the receptors. This can help prevent the cancer from growing and spreading.

According to the ACS, around two-thirds of breast cancer cases are hormone receptor-positive.

Sex and gender exist on spectrums. This article will use the terms “male,” “female,” or both to refer to sex assigned at birth. Click here to learn more.

A number of factors may increase the risk of developing ER-positive breast cancer. These include:

Sex: Females are far more likely than males to develop any type of breast cancer. In males, around 90% of breast cancer cases are hormone receptor-positive, and males with health conditions that increase estrogen levels have an increased risk of this type of cancer.

Age: The risk of hormone receptor-positive breast cancer increases with age.

Lifetime exposure: Females with a longer lifetime exposure to estrogen and progesterone may have a higher risk of developing hormone receptor-positive breast cancer. This includes people who:

  • start menstruating early
  • reach menopause late
  • do not have children

Hormone treatment: The National Cancer Institute notes that having hormone treatment may increase the risk of hormone receptor-positive breast cancer. This includes taking hormone replacement therapy during menopause. Females whose mothers took a hormone treatment called diethylstilbestrol during pregnancy between 1940 and 1971 may also have a higher risk.

Other factors: The following may increase exposure to breast cancer-related hormones:

  • excessive alcohol consumption
  • a high body mass index in early life
  • obesity after menopause
  • a lack of physical activity

Learn more about male breast cancer.

The symptoms of ER-positive breast cancer are similar to those of many other types of breast cancer. The most common symptom is a lump in the breast.

Other symptoms can include:

A lump is a common symptom of breast cancer, but not all breast cancers cause lumps.

Learn more about other symptoms of breast cancer.

If a person notices a lump or other breast changes, or if these appear on routine screening, a doctor may suggest an ultrasound scan to gather more information.

If breast cancer is a possibility, the doctor usually recommends a biopsy to confirm:

  • whether cancer is present
  • the type of cancer
  • whether hormone receptors play a role in the growth of the cancer cells

During a biopsy, a medical professional removes a small amount of breast tissue or the entire tumor. They then send what they have removed to a laboratory for an analysis that includes immunohistochemistry testing.

The results of these tests help a doctor determine the best treatment plan.

Learn more about what happens during a breast biopsy.

Treatment for ER-positive breast cancer aims to reduce estrogen levels or stop estrogen from acting on ERs in the cancerous cells.

The choice of treatment depends on many factors, including:

  • the type of breast cancer
  • whether and to what extent the cancer has spread
  • the person’s overall health

The following hormone therapy options can help treat ER-positive breast cancer.

Luteinizing hormone-releasing hormone agonists

Another name for this type of drug is “LHRH agonist.” These medications can “turn off” the production of estrogen in the ovaries. As a result, less estrogen is available to support the growth of ER-positive breast cancer.

Examples of these drugs include:

  • goserelin acetate (Zoladex)
  • leuprolide (Lupron)
  • triptorelin pamoate (Trelstar)

This treatment is most common among females who have not entered menopause and have early stage ER-positive breast cancer. A doctor may combine this approach with another treatment, such as tamoxifen (Nolvadex, Soltamox).

Side effects

These drugs can trigger temporary symptoms of menopause, such as:

Aromatase inhibitors

Aromatase inhibitors block an enzyme called aromatase, which converts the hormone androgen into estrogen. Blocking aromatase reduces estrogen levels, so less estrogen is available to encourage the growth of ER-positive breast cancer cells.

Examples of aromatase inhibitors include:

  • anastrozole (Arimidex)
  • exemestane (Aromasin)
  • letrozole (Femara)

These medications only work after menopause. They target the adrenal gland and fat tissue, where the body makes estrogen, but they do not prevent the ovaries from producing estrogen. After menopause, females receive much less estrogen from their ovaries than they did before menopause.

Side effects

Side effects of aromatase inhibitors include muscle pain and joint pain or stiffness. In the long term, they may also increase the risk of osteoporosis.

Selective estrogen receptor response modulators

Selective estrogen receptor response modulators (SERMs) attach to and block estrogen receptors in breast cells. This stops the estrogen from signaling to the cells to grow.

Examples of SERMs include:

  • tamoxifen (Nolvadex, Soltamox)
  • toremifene (Fareston) for people with advanced ER-positive breast cancer after menopause

A doctor may prescribe one of these drugs with another medication.

Side effects

Possible adverse effects of SERMs include:

  • changes in mood
  • hot flashes
  • vaginal dryness or unusual discharge

Less commonly, SERMs may increase the risk of:

ER downregulators

These drugs also block the effects of estrogen. They change the shape of ERs so that they do not work as well. They also reduce the number of ERs on breast cells.

One example of an ER downregulator (ERD) is fulvestrant (Faslodex). A doctor may prescribe it:

  • to treat advanced ER-positive breast cancer in females who have gone through menopause
  • when other hormone therapy medications are not working

Side effects

Possible adverse effects of ERDs include:

Prolonged use of ERDs can increase the risk of osteoporosis.

Preventive surgery

If a person has not yet gone through menopause, a doctor may recommend surgery to remove the ovaries. This can reduce estrogen levels in the body and may help prevent breast cancer from returning.

However, this invasive approach can have a considerable impact. For example, it means that a person cannot conceive. A doctor should speak with the person about all the factors to consider.

Current guidelines from the American College of Physicians suggest that people with an average risk of breast cancer undergo screening every 2 years from the age of 50–74. Those aged 40–49 years should ask their doctor about whether screening is a good idea.

Other organizations have different recommendations. For example, the ACS recommends annual breast screenings for females aged 45–54 years.

However, each person’s situation is different. A doctor may recommend a different screening schedule for someone with a higher risk of breast cancer.

The outlook for people with ER-positive breast cancer tends to be good, especially when a doctor diagnoses it early.

A person with an early diagnosis of any type of breast cancer has a 99% chance of living for at least another 5 years, and often longer, the ACS reports.

However, if the cancer has spread to other organs, the chance of surviving for at least another 5 years is 29%, it notes.

Taking these steps may ultimately lead to a better outlook if a person develops breast cancer:

  • knowing and recognizing the signs
  • regularly examining the breasts for abnormalities
  • seeking help if symptoms appear
  • undergoing regular screening, if a doctor recommends it
  • getting appropriate treatment

Q:

I have been using the pill as birth control for several years. Will this increase my risk of breast cancer?

A:

Studies looking into the link between birth control pills and the risk of breast cancer have consistently shown that the risk of breast and cervical cancers increases in people who take birth control pills.

For breast cancer specifically, studies have shown that people who had ever used oral contraceptives had a slight (7%) increase in the relative risk of breast cancer, compared with those who had never taken these pills.

And the longer a person uses oral contraceptives, the greater the risk of breast cancer seems to be.

However, this may depend on the hormone formulation, as there are many types and combinations of hormones in these contraceptives. The risk seems to decline after people stop taking the pill. In one study, this was evident by 10 years following cessation.

Christina Chun, MPH Answers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.

When someone has ER-positive breast cancer, the cancer cells have receptors for the hormone estrogen. This type of breast cancer typically responds favorably to treatments that block or destroy ERs or otherwise lower the body’s estrogen levels.

The outlook tends to be good, especially for people who receive a diagnosis and appropriate treatment in the earlier stages of the disease.

It is important for people to regularly examine their breasts for any unusual changes and undergo regular screening when this is appropriate.