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Hormone Blockers For Breast Cancer

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What Are Hormone Receptors

Adjuvant Hormonal Therapy for Estrogen Receptor Positive Early Stage Breast Cancer – Mayo Clinic

Breast cancers that are hormone receptor positive have receptors for the female hormones oestrogen and/or progesterone on the inside of the cancer cells.

In breast cancer cells that are hormone receptor positive, oestrogen and/or progesterone, which are naturally produced in the body, make the cancer grow. You can think of it as the receptor being the lock and oestrogen being the key. The oestrogen fits into the receptor and switches the cancer cell on, causing it to grow. Hormone therapy for breast cancer can starve cancer cells by upsetting this process.

Testing for hormone receptors is part of the routine pathology testing following surgery. Testing is done on a core biopsy sample if surgery is not planned.

Your doctor will be able to tell you if your breast cancer is hormone receptor positive or not. Most, but not all breast cancer is hormone receptor positive.

The hormonal therapies described in this brochure only work against breast cancers that are hormone receptor positive. Other treatments need to be used for cancers that are hormone receptor negative.

Mood Swings Depression And Sleep Disturbances

These side effects sometimes happen with both tamoxifen and aromatase inhibitors. If they do, tell your doctor.

What helps: If you have depression, there are treatments that can help, including medications and therapy. Other approaches that may help with mood swings, depression, and sleep disturbances include cognitive behavioral therapy , tai chi, and meditation.

Remember, depression is a medical condition. Itâs more than having the âbluesâ or the normal range of emotions we all have. Donât hesitate to tell your doctor or therapist.

What Are The Side Effects Of Hormonal Therapy

Side effects vary greatly from one person to the next for both types of hormonal medications. Some have no symptoms at all. Most have very tolerable side effects. Some patients will need to change hormonal therapy medications to find the best balance of cancer benefit versus side effects. Several side effects that are rather common for both tamoxifen and aromatase inhibitors are hot flashes, night sweats, joint pain, and vaginal dryness. Below, we list some of the other specific side effects for both drugs.

  • Increased risk of uterine cancer
  • Increased risk of developing blood clots
  • Slows normal bone loss in most women
  • Cannot be taken during pregnancy because of risk of birth defects or fetal death
  • Can temporarily induce menopause in pre-menopausal women.
  • Can worsen bone loss in women
  • Muscle and joint aches and pains

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Surgical Removal Of The Ovaries

The operation to remove the ovaries is called oophorectomy. Surgical removal of the ovaries is a permanent way to reduce the levels of oestrogen.

It is a very effective treatment to stop early breast cancer returning or to slow the progress of metastatic cancer. This can also reduce the risk of developing ovarian cancer.

Surgery to remove the ovaries can be done with keyhole surgery or with an open operation .

Your surgeon will discuss with you the pros and cons of these different techniques. Oophorectomy is done under a general anaesthetic .

Usually the fallopian tubes are also removed but the uterus is left intact. After oophorectomy, the symptoms of menopause may come on suddenly. This is different to turning off the ovaries with medication which brings menopausal symptoms on gradually

Surgery To Stop The Ovaries From Working

Mechanisms associated with resistance to tamoxifen in estrogen receptor ...

This is also a type of ovarian ablation. You might choose to have an operation to remove your ovaries instead of having drug treatment to stop them working. You have this operation as keyhole surgery. It is called laparoscopic oophorectomy and you have it under general anaesthetic . You usually stay in hospital overnight.

The surgeon makes a number of small cuts into your tummy . They put a long bendy tube called a laparoscope into one of the cuts. The laparoscope connects to a video screen.

The surgeon puts small instruments through the other cuts to carry out the operation and remove the ovaries. They close the cuts with stitches and cover them with small dressings.

Removing your ovaries causes you to have a sudden menopause. The symptoms include hot flushes, sweating and mood swings.

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How To Choose The Best Kind Of Hormone Therapy

There are many hormone therapy types to cure breast cancer such as

Selective Estrogen Receptor Modulators

Even known as SERMs, these medications obstruct breast cancer cells from getting attached to estrogen. SERMs impede the effects of estrogen merely in breast tissue but not in other tissues within the body.

These drugs are traditionally only used in premenopausal women.

The commonly used SERMs consist


This medication stops estrogen from attaching to cells and thereby disables cancer from growing and dividing. People who have tamoxifen for a decade after breast cancer treatment are less supposed to see the cancer recurrence and more supposed to live longer in comparison to the ones who take the medicine for just 5 years.


This medication is approved only to cure breast cancer that has extended to other body parts and might not be useful in persons who have seen less success with tamoxifen.


This is an injected estrogen receptor-blocking medication that is usually used to cure advanced breast cancers. Different from other SERMs, it obstructs the effect of estrogen all through the total body.

Aromatase Inhibitors

AIs obstruct estrogen production from fat tissue, however, have no consequence on the estrogen made by the ovaries.

Common AIs consist

Ovarian Ablation or Suppression

Surgical ablation is carried on by the removal of ovaries. Without the manufacturing of estrogen from the ovaries, one will move into permanent menopause.

Having Hormonal Therapy For Breast Cancer

Hormonal therapy drugs reduce the risk of breast cancer coming back. It is important to take it for as long as you have been prescribed it for. Try to make taking it part of your daily routine so it becomes a habit.

Most women cope well with the side effects of hormonal therapy. They may be more of a problem in the first few months, but usually get better over time. If the side effects do not improve or are difficult to cope with, talk to your specialist nurse or cancer doctor. They can prescribe drugs to help and suggest ways of coping.

If you are still having problems after this, then your cancer doctor may suggest changing to a different type of hormonal therapy.

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There Is No Hormone Called Estrogen

First, a primer on what exactly estrogen is. There is actually no hormone called estrogen. Estrogens are a class of hormones. There are three different forms of estrogens in the body: estradiol, estriol and estrone. Although they are all pretty similar in function, they vary in potency. Estrogens found in plants, like soy, are also sometimes simply called estrogen, although their effects may differ from those of the estrogens produced in the body.

Estradiol is the dominant estrogen circulating prior to menopause. It is produced mainly in the ovaries. In most cases, this is the most potent form of estrogen. During pregnancy, the dominant form is estriol, produced by the placenta. And during menopause, when the levels of estradiol decrease, the dominant estrogen is estrone, produced in fat tissue.

The ovaries stop producing estrogens during menopause, resulting in lower levels of estrogens in the body. Yet other organs, including fat and the brain, continue to produce them. There are still estrogens doing whatever they were doing before, but because their levels are lower, they are not doing their work as effectively.

One class of estrogen blockers that is often prescribed for women with estrogen receptor-positive breast cancer does its job by blocking estrogens from getting to the receptors of the cells in the body, including cancer cells. The body still produces estrogens, but their effects are blocked in some cells.

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If Cancer Has Come Back Or Spread

Q& A: Would you recommend an estrogen blocker, genetic testing if you have naturally high estroge…

Hormone therapy can be used to treat breast cancer that has come back or that has spread to another part of the body .

Its given either alone or with other treatments, depending on what treatments you had before.

If your breast cancer came back during or after treatment with hormone therapy, you may be offered a different type of hormone therapy.

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How To Switch To A Tamoxifen Alternative

Hormone therapy for breast cancer is typically started after surgery. Switching to a tamoxifen alternative may depend on the response to treatment. The timeline for hormone therapy may look like one of the following:

  • Start an aromatase inhibitor two to three years after treatment with tamoxifen. Continue taking the aromatase inhibitor for two to three years for a total of five years of treatment with tamoxifen and the aromatase inhibitor. This treatment timeline is appropriate for postmenopausal women.
  • Start an aromatase inhibitor two to three years after treatment with tamoxifen. Continue taking the aromatase inhibitor for five years for a total of seven to eight years of treatment with tamoxifen and the aromatase inhibitor. This treatment timeline is appropriate for postmenopausal women.
  • Start an aromatase inhibitor five years after treatment with tamoxifen and ovarian suppression therapy. Continue taking the aromatase inhibitor for five years for a total of 10 years of treatment with tamoxifen and the aromatase inhibitor. This treatment timeline is appropriate for women who are premenopausal at the time of diagnosis.

An oncologist will recommend follow-up care every few months to assess the effects after treatment with hormone therapy. They will also assess the risk of recurrence of cancer and determine the next steps for treatment as needed.

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When Is Hormone Therapy Used For Breast Cancer

Hormone therapy is often used after surgery to help reduce the risk of the cancer coming back. Sometimes it is started before surgery .

It is usually taken for at least 5 years. Treatment longer than 5 years might be offered to women whose cancers have a higher chance of coming back. A test called the Breast Cancer Index might be used to help decide if a woman will benefit from more than 5 years of hormone therapy.

Hormone therapy can also be used to treat cancer that has come back after treatment or that has spread to other parts of the body.

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What Are The Side Effects Of Hormone Therapy

The side effects of hormone therapy depend largely on the specific drug or the type of treatment . The benefits and harms of taking hormone therapy should be carefully weighed for each person. A common switching strategy used for adjuvant therapy, in which patients take tamoxifen for 2 or 3 years, followed by an aromatase inhibitor for 2 or 3 years, may yield the best balance of benefits and harms of these two types of hormone therapy .

Hot flashes, night sweats, and vaginal dryness are common side effects of all hormone therapies. Hormone therapy also may disrupt the menstrual cycle in premenopausal women.

Less common but serious side effects of hormone therapy drugs are listed below.


  • breathing problems, including painful breathing, shortness of breath, and cough
  • loss of appetite

Side Effects Of Tamoxifen And Toremifene

Tamoxifen anti estrogen blocker

The most common side effects of tamoxifen and toremifene are:

  • Vaginal dryness or discharge
  • Changes in the menstrual cycle

When tamoxifen treatment starts, a small number of women with cancer that has spread to the bones might have a tumor flare which can cause bone pain. This usually decreases quickly, but in some rare cases a woman may also develop a high calcium level in the blood that is hard to control. If this happens, the treatment may need to be stopped for a time.

Rare, but more serious side effects are also possible:

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Hot Flashes And Night Sweats

Hot flashes and night sweats happen to a lot of women during menopause. Theyâre also side effects of both tamoxifen and aromatase inhibitors.

âFor tamoxifen, younger premenopausal women whose ovaries are still working tend not to have symptoms that are as severe,â says Patricia Ganz, MD, director of the Center for Cancer Prevention & Control Research at UCLAâs Jonsson Comprehensive Cancer Center. âAs you get nearer to the age of natural menopause, in your 40s and 50s, these symptoms can get worse.â

What helps: To manage hot flashes and night sweats, Mayer recommends starting with environmental approaches, like keeping your bedroom cool at night, dressing in layers, and keeping a fan on.

You can also keep a bottle of cold water by your bed or keep an ice pack under your pillow. Acupuncture may also help with many side effects linked to aromatase inhibitors, including hot flashes, Mayer says.

But if these approaches donât help and hot flashes and night sweats are interfering with your daily life, medication might be helpful.

What helps: âCertain medicines that are used to treat anxiety or depression also actually can treat hot flashes,â says Jessica Jones, MD. Sheâs an assistant professor in the oncology division of The University of Texas Health Science Center McGovern Medical School in Houston.

Jones is talking about medications such as selective serotonin reuptake inhibitors , serotonin-norepinephrine reuptake inhibitors , and gabapentin.

Hormone Therapy Has A Bigger Impact Than Chemotherapy On Womens Quality Of Life

Cellules cancéreuses. Expression de la protéine PML en rouge et du gène ZNF703 en vert dans des cellules de la lignée de cancer du sein MCF7. ©Inserm/Ginestier, Christophe

Analysis of the CANTO cohort published in the journal Annals of Oncology will upset received wisdom on the effects that hormone therapy and chemotherapy have on the quality of life in women with breast cancer. Contrary to the commonly held view, 2 years after diagnosis, hormone therapy, a highly effective breast cancer treatment worsens quality of life to a greater extent and for a longer time, especially in menopausal patients. The deleterious effects of chemotherapy are more transient. Given that current international guidelines recommend the prescription of hormone therapy for 5 to 10 years, it is important to offer treatment to women who develop severe symptoms due to hormone antagonist medication and to identify those who might benefit from less prolonged or intensive treatment strategies.

This work was directed by Dr Inès Vaz-Luis, specialist breast cancer oncologist and researcher at Gustave Roussy in the lab Predictive Biomarkers and Novel Therapeutic Strategies in Oncology .

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What Are Hormones And Hormone Receptors

Hormones are substances that function as chemical messengers in the body. They affect the actions of cells and tissues at various locations in the body, often reaching their targets through the bloodstream.

The hormones estrogen and progesterone are produced by the ovaries in premenopausal women and by some other tissues, including fat and skin, in both premenopausal and postmenopausal women and in men. Estrogen promotes the development and maintenance of female sex characteristics and the growth of long bones. Progesterone plays a role in the menstrual cycle and pregnancy.

Estrogen and progesterone also promote the growth of some breast cancers, which are called hormone-sensitive breast cancers. Hormone-sensitive breast cancer cells contain proteins called hormone receptors that become activated when hormones bind to them. The activated receptors cause changes in the expression of specific genes, which can stimulate cell growth.

Breast cancers that lack ERs are called ER negative, and if they lack both ER and PR they may be called HR negative.

Approximately 67%80% of breast cancers in women are ER positive . Approximately 90% of breast cancers in men are ER positive and approximately 80% are PR positive .

Who Should Use Tamoxifen

Hormone replacement therapy and potential breast cancer risks

Tamoxifen can help women and men with hormone receptor-positive breast cancer. The drug can lower the risk of breast cancer in:

  • Women who are high-risk of breast cancer due to a family history of disease or mutated breast cancer genes.
  • Women and men who have already been diagnosed with breast cancer to prevent recurrence of cancer, including:
  • Development of breast cancer in the opposite, untreated breast.
  • American Cancer Society. Breast Cancer Hormone Receptor Status. Accessed 11/18/2021.
  • American Cancer Society. Hormone Therapy for Breast Cancer. Accessed 11/18/2021.
  • American Cancer Society. Tamoxifen and Raloxifene for Lowering Breast Cancer Risk. Accessed 11/18/2021.
  • Low-Dose Tamoxifen May Be an Option to Reduce Risk of Recurrence, Invasive Disease After Non-Invasive Breast Cancer. Accessed 11/18/2021.
  • Tamoxifen . Accessed 11/18/2021.
  • National Breast Cancer Foundation. Hormone Therapy. Accessed 11/18/2021.
  • National Cancer Institute. Hormonal Therapy. Accessed 11/18/2021.
  • Susan G. Komen. Side Effects of Tamoxifen. Accessed 11/18/2021.
  • Susan G. Komen. Tamoxifen. Accessed 11/18/2021.
  • Susan G. Komen. Tamoxifen and Raloxifene to Reduce Breast Cancer Risk. Accessed 11/18/2021.
  • Susan G. Komen. Tumor Characteristics: Hormone Receptor Status. Accessed 11/18/2021.

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Hormones And Breast Cancer

The hormones estrogen and progesterone make some breast cancers grow. They are called hormone-sensitive breast cancers. Most breast cancers are sensitive to hormones.

Estrogen and progesterone are produced in the ovaries and other tissues such as fat and skin. After menopause, the ovaries stop producing these hormones. But the body continues to make a small amount.

Hormone therapy only works on hormone-sensitive cancers. To see if hormone therapy may work, doctors test a sample of the tumor that has been removed during surgery to see if the cancer might be sensitive to hormones.

Hormone therapy can work in two ways:

Other Serms Such As Evista And Fareston

Raloxifene and toremifene are other SERMs that act similarly to tamoxifen. They stop cancer growth by binding to estrogen receptors and blocking the ability of estrogen to bind to these receptors. However, SERMs can also mimic the effects of estrogen in other parts of the body, such as the uterus, which can increase the risk of certain cancers. These drugs are not usually recommended if previous treatment with tamoxifen has not been successful. Toremifene is only approved for the treatment of metastatic breast cancer in postmenopausal women, so its uses are more limited than those of tamoxifen.

Some healthcare providers may prescribe raloxifene over tamoxifen due to its lower risk of serious side effects, such as uterine cancer. Raloxifene may be prescribed to postmenopausal women with osteoporosis who are at a high risk of invasive breast cancer. However, raloxifene may be less effective at preventing breast cancer than tamoxifen and has only been tested in postmenopausal women. On the other hand, tamoxifen is an option to prevent breast cancer in premenopausal women.

SERMs are generally taken by mouth. Side effects may include hot flashes, muscle or joint pain, and leg cramps. Serious side effects may include an increased risk of uterine or endometrial cancer and blood clots in the legs or lungs.

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