Having ER-positive breast cancer means a person’s breast cancer cells have estrogen receptors (ERs). Receptors are proteins present in cells that can attach to substances in the blood.

Normal breast cells have receptors that attach to estrogen and progesterone, and these hormones help the cells grow.

Some breast cancer cells also have these receptors. Breast cancer cells with estrogen receptors are called ER-positive, and those with progesterone receptors are called PR-positive.

When these hormones attach to the receptors, they stimulate the cancer to grow.

If cancer cells have one or either of these receptors, doctors may refer to them as hormone receptor-positive, or hormone-positive, breast cancer.

This article examines breast cancer that is ER-positive. It looks at symptoms, diagnosis and treatment, outlook, and more.

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When diagnosing breast cancer, doctors will take a biopsy of breast tissue. They will test this biopsy to see if the cells have estrogen or progesterone receptors, or both. If they do, doctors refer to it as hormone receptor-positive breast cancer.

Not having any hormone receptors means the breast cancer is hormone receptor-negative. Knowing the hormone receptor status is important in deciding treatment options.

According to the American Cancer Society (ACS), around two-thirds of breast cancer cases are hormone receptor-positive.

Hormone receptor-positive cancers — including those that are ER-positive — tend to grow more slowly than those that are hormone receptor-negative.

The treatment for hormone receptor-positive cancers involves taking hormone drugs that lower estrogen levels or block estrogen receptors. This can help prevent the cancer from growing and spreading.

People with hormone receptor-positive breast cancers usually have a better outlook in the short term. However, these cancers can sometimes return many years after treatment.

A note about sex and gender

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.

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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.
  • Hormone 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:
  • Hormone treatment: The ACS notes that having hormone treatment may increase the risk of hormone receptor-positive breast cancer. This includes taking hormone replacement therapy during menopause.
  • Other factors: The following factors 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

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 of breast cancer 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 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.

Different organizations have slightly different recommendations for breast cancer screening. The ACS recommends yearly breast screenings for females ages 45 to 54 years.

It also states that females between the ages of 40 and 44 years should have the choice to start annual breast cancer screening with mammograms (X-rays of the breast) if they wish to do so.

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

A person can work out their risk of breast cancer using the Tyrer-Cuzick model, available online. According to the National Cancer Institute (NCI), a person with average risk of breast cancer does not need screening before the age of 40 years.

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%, the organization 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


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


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.

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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.