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Estrogen Blockers For Breast Cancer

Side Effects Of Estrogen Blockers

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

Side effects of estrogen blockers can vary depending on the drug. The most commonly reported symptoms are:

  • hot flashes
  • vaginal dryness
  • menstrual cycle changes

More serious but less common side effects of estrogen blockers can include blood clots or increased risk of developing uterine cancer. Postmenopausal women face an even higher chance of a uterine cancer diagnosis.

A very rare but potential side effect of antiestrogen therapy is a stroke, so its essential not to ignore any sudden feelings of confusion, headaches, or trouble moving or speaking.

Youll want to call 911 immediately if any of these issues arise while taking estrogen blockers.

Who Can And Cannot Take Anastrozole

Anastrozole is not suitable for some people. Tell your doctor before starting on this medicine if you:

  • have had an allergic reaction to anastrozole or any other medicines in the past
  • still have periods
  • are pregnant, trying to get pregnant or breastfeeding
  • have serious kidney or liver disease
  • have been told you have fragile or brittle bones

Previous Breast Cancer Or Lump

If you have previously had breast cancer or early non-invasive cancer cell changes in breast ducts, you have a higher risk of developing it again, either in your other breast or in the same breast.

A benign breast lump does not mean you have breast cancer, but certain types of breast lumps may slightly increase your risk of developing cancer.

Some benign changes in your breast tissue, such as cells growing abnormally in ducts , or abnormal cells inside your breast lobes , can make getting breast cancer more likely.

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Hormone Therapy For Breast Cancer

Some types of breast cancer are affected by hormones, like estrogen and progesterone. The breast cancer cells have receptors that attach to estrogen and progesterone, which helps them grow. Treatments that stop these hormones from attaching to these receptors are called hormone or endocrine therapy.

Hormone therapy can reach cancer cells almost anywhere in the body and not just in the breast. It’s recommended for women with tumors that are hormone receptor-positive. It does not help women whose tumors don’t have hormone receptors .

Who Should Use Tamoxifen

Estrogen Blockers

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.
  • BreastCancer.org. Low-Dose Tamoxifen May Be an Option to Reduce Risk of Recurrence, Invasive Disease After Non-Invasive Breast Cancer. Accessed 11/18/2021.
  • BreastCancer.org. 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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How Exactly Is Estrogen Linked To Breast Cancer

While not always the case, estrogen does play a role in most common types of breast cancer around 80% of cases according to evidence. While scientists and researchers are still working to build a better understanding of this complex area, current research points to how much estrogen you are exposed to over time and how your cells respond to the hormone as being the main factors.

What Are The Side Effects Of Hormonal Therapy

Tamoxifen: Tamoxifen is associated with some side effects similar to symptoms of menopause, which include hot flashes, irregular menstrual periods and vaginal discharge or bleeding. Not all women will experience these symptoms. More serious side effects can also occur as a result of long-term use of tamoxifen. There is a small increase in the number of blood clots in individuals taking tamoxifen. Individuals taking tamoxifen have a slightly increased risk of developing cataracts. In addition, tamoxifen appears to increase a womans risk of developing uterine cancer by about 2-3 times that of the general population.5-9 This risk of uterine cancer is similar to that for women taking postmenopausal estrogen replacement therapy. Since the majority of uterine cancers can be detected at an early stage when they are highly curable, the overall benefit of anti-estrogen treatment in breast cancer patients probably outweighs the risk of uterine cancer. All women who have a uterus and are receiving anti-estrogen therapy should undergo regular gynecologic examinations. The most common side effects caused by tamoxifen are

  • Hot flashes
  • Discharge or Irritation

These side effects are not usually serious, but they can be bothersome. Other side effects that are rare but are more dangerous include:


  • Lake DE, Hudis C. Aromatase Inhibitors in Breast Cancer: An Update. Cancer Control. 2002 9:490-498.
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    Hormonal Therapy Treatment Of Metastatic Or Recurrent Breast Cancer

    When breast cancer occurs outside of the breast in the bones, lungs, liver or other organs, it is referred to as metastatic. Patients with breast cancer may also experience a recurrence of cancer after initial treatment with hormonal therapy. Patients with newly diagnosed metastatic breast cancer benefit from initial treatment with hormonal therapy and those with recurrent cancer may benefit from switching to a different hormonal therapy.

    Recommendations set forth by a convening Expert Panel specifically for women with HR-positive, metastatic breast cancer included the following.27

    Aromatase Inhibitors And Treatment For Early And Locally Advanced Breast Cancers

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

    For women with hormone receptor-positive breast cancer, treatment with an aromatase inhibitor lowers the risk of :

    • Breast cancer in the opposite breast
    • Death from breast cancer

    Among postmenopausal women with hormone receptor-positive breast cancer, aromatase inhibitors offer the same or slightly greater benefit compared to tamoxifen alone .

    Anastrozole, exemestane and letrozole are equally effective and have similar side effects . However, you may tolerate one drug better than another.

    Learn about aromatase inhibitors and treatment for metastatic breast cancer.

    For a summary of research studies on aromatase inhibitors and early breast cancer, visit the Breast Cancer Research Studies section.

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    Symptoms Of Estrogen Dominance In Men

    If we are talking about estrogen dominance as a bad thing, it is not because estrogen is detrimental by itself. It is a hormone in males and females, and even males should have a reasonable level. Testosterone is not just important for sexual health. Testosterone is also essential for maintaining lean muscle mass and bone density. Additionally, testosterone regulates the metabolism of fat.

    The problem starts when this hormone becomes abundant in a mans body. Then, we would begin to experience several problems and various symptoms.

    The most important are as follows :

    Is All Breast Cancer Related To Estrogen

    Not all breast cancer is linked to estrogen, but estrogen receptor positive cancers are the most common type of breast cancer. And out of ER positive breast cancers, studies also show that around 65% of those cases also respond to progesterone.

    Estrogen receptor positive breast cancer means that estrogen encourages the growth of the cancer cells . Part of the treatment plan for these types of cancers usually involves medications that lower estrogen levels in the body or help block the estrogen receptors .

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    You Have Natural Aromatase Inhibitors Options

    The natural options listed below do not have any the toxic and dangerous side effects compared to the many synthetic aromatase inhibitors may provide.

    A group of plant compounds called flavonoids that are widely found in whole foods have shown an inhibitory effect on the enzyme aromatase. They include:

    • Black, green, and matcha teas
    • Grape skins
    • Genistein from fermented soy

    Evidence From The Historical Use Of Estrogens To Treat Metastatic Breast Cancer

    Estrogen Blockers

    The application of high-dose estrogen therapy for the treatment of metastatic breast cancer was the first use of a chemical therapy to treat any cancer successfully . Estrogen therapy became the standard of care to treat metastatic breast cancer in postmenopausal patients until the introduction of tamoxifen , a nonsteroidal antiestrogen . Tamoxifen became the gold standard for the treatment of ER-positive breast cancer for the next 20 years. Estrogen was all but abandoned as a treatment option, but Ingle and colleagues completed a provocative trial of tamoxifen versus the synthetic estrogen diethylstilbestrol in metastatic breast cancer . Responses were equivalent with fewer side effects with tamoxifen, but a re-analysis years later demonstrated that survival was significantly improved with DES .

    Towards the end of his distinguished career, Professor Sir Alexander Haddow FRS reflected on the remarkable responses noted with estrogen in some tumors, often when treatment was more than a decade past menopause: The extraordinary extent of tumour regression observed in perhaps 1% of post-menopausal cases has always been regarded as of major theoretical importance, and it is a matter for some disappointment that so much of the underlying mechanisms continues to elude us.

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    Length Of Treatment With An Aromatase Inhibitor

    Randomized clinical trials have compared outcomes for women who used aromatase inhibitors for 10 years versus 5 years . Taking an aromatase inhibitor for 10 years :

    • Improves disease-free survival
    • Lowers the risk of cancer in the opposite breast

    However, overall survival is the same whether a woman takes an aromatase inhibitor for 5 years or 10 years . For most women, the benefit of the extra 5 years of treatment is small .

    Women who take an aromatase inhibitor for more than 5 years continue to have side effects from the drug, including a higher number of bone fractures and a higher rate of osteoporosis .

    Talk with your health care provider about how long you should take an aromatase inhibitor.

    Learn about the importance of completing treatment with an aromatase inhibitor.

    Possible side effects of aromatase inhibitors include muscle pain, joint pain and menopausal symptoms .

    Aromatase inhibitors also cause a loss of bone density. Youll get a baseline measure of your bone density so changes in your bone density can be monitored.

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    What If I Forget To Take It

    If you forget to take your medicine, just skip the missed dose. Take your next dose at the normal time.

    Do not take a double dose to make up for a forgotten one. If you forget doses often, it may help to set an alarm to remind you. You could also ask your pharmacist for advice on other ways to help you remember to take your medicine.

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    Antiestrogen Vs Estrogen Blockers

    Both antiestrogen and estrogen blockers aim to slow or stop the progression of breast cancer. The two different treatments dont work the same way, though.

    Tamoxifen, a widely used estrogen blocker, stops estrogen from affecting breast tissue. Aromatase, an antiestrogen therapy, lowers the production of estrogen in postmenopausal women.

    Tamoxifen is well known and widely used as chemoprevention a medication to prevent disease for women with a high risk of developing invasive breast cancer, according to

    , researchers found that when postmenopausal women in the increased risk category took tamoxifen for 5 years, it lowered their risk of developing invasive breast cancer by 50 percent.

    A 2017 study found that use of tamoxifen and antiestrogen medications led to a 50 to 65 percent decrease in breast cancer development in high risk groups.

    Both estrogen blockers and antiestrogen therapies are effective, but there are side effects, too. Its important to weigh the benefits and risks with your care team before deciding on this course of action.

    Anastrozole May Cause Side Effects Tell Your Doctor If Any Of These Symptoms Are Severe Or Do Not Go Away:

    Extending Estrogen-Blocking Tamoxifen Therapy for Breast Cancer Patients — Sloan-Kettering
    • joint, bone, or muscle pain
    • breast pain
    • difficulty falling asleep or staying asleep
    • nervousness
    • difficulty swallowing or breathing
    • swelling of the eyes, face, lips, tongue, throat, arms, hands, feet, ankles, or lower legs

    Anastrozole may cause or worsen osteoporosis. It can decrease the density of your bones and increase the chance of broken bones and fractures. Talk to your doctor about the risks of taking this medication and to find out what you can do to decrease these risks.

    Anastrozole may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.

    If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration’s MedWatch Adverse Event Reporting program online or by phone .

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    What Is Unique About The Young Mammary Gland That Makes It So Susceptible To Cancer Induction And Protection

    The fact that two crucial reproductive events, menarche and young age at parity, have the greatest effect on lifetime breast cancer risk suggests that the young mammary gland represents a crucial window in tumorigenic susceptibility. Why this is the case is less clear. Based on the epidemiological evidence for this, a few hypotheses have been generated, but again few have been tested experimentally, and this work is largely restricted to rodent models.

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    What Are Aromatase Inhibitors

    To begin with, I want to be very clear that you should never stop any prescription medications without discussing this with your primary care doctor.

    Aromatase inhibitors are hormonal therapies used to treat estrogen-positive breast cancer. Common names for these drugs are Aromasin, Anastrozole, and Letrozole. They are technically designed to stop tumor growth and recurrence. Aromatase inhibitors are typically used to treat postmenopausal women with ER-positive breast cancer. They are not usually given to pre-menopausal women because they dont block the estrogen production in the ovaries.

    The main goal of these drugs is to block the synthesis of estrogen from testosterone by the enzyme aromatase. The drugs block the action of this enzyme and thereby lower the estrogen level it may slow the growth of cancers and lower the risk of recurrence.

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    How Long Should You Take Hormone Therapy

    The American Society of Clinical Oncology updated their guidelines for the use of adjuvant endocrine therapy for women with hormone receptor-positive breast cancer extending the duration of tamoxifen treatment beyond the five-year standard. Specifically, women in two large studies who used tamoxifen for a total of 10 years experienced modest gains in survival compared with those who used tamoxifen for five years. As well, women treated for 10 years had a lower risk of recurrence and of developing cancer in the other breast.

    Aromatase inhibitors have been shown to provide a somewhat higher disease-free survival rate than tamoxifen. A number of randomized trials have compared 5 years with 10 years and In general, these trials have shown no additional benefit from further endocrine therapy in the lymph nodenegative population. The results in lymph nodepositive patients have been mixed, with one trial showing some benefit and the other trials showing little or no benefit.

    As always, patients are encouraged to discuss all treatment options with their physician in order to make the best decision for optimal care.

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    What Is Estrogen Dominance

    Estrogen is a sex hormone. It is the most prevalent hormone in women, as opposed to testosterone. However, all men have estrogen and testosterone. The normal circulating levels of both hormones stay in balance by the testis.

    However, other organs and parts of the body contribute to either of them. Estrogen dominance in men happens when the balance between normal levels of testosterone and estrogen is lost. When estrogen becomes excessively high in a mans standard, it will start opposing testosterone. Thats when you start getting feminizing symptoms and other health problems.

    Estrogen dominance is not meant to be a part of the life cycle, but sometimes it happens that way. When men age, their testis produce less and less testosterone. But our modern world contributes to this hormonal prevalence. As we become more sedentary, we tend to accumulate body fat.

    Testosterone is then stolen by your body fat and converts into estrogen.

    The same happens with the food we eat and the products we use every day. We are constantly hit by synthetic substances that promote estrogen dominance in a mans body. Thats why recently, estrogen dominance is starting to resonate in the vocabulary of mens health .

    Estrogen Exposure Over Time Is Linked To Breast Cancer

    The longer your body is exposed to estrogen throughout your life, the more it appears to increase your risk for estrogen-related breast cancer. This helps explain why most breast cancer diagnoses occur later in life, after a lifetime of exposure to estrogen.

    But it gets more interesting. Even though breast cancer risk generally increases as you get older, if you start your period later in life , your risk goes down simply because you had a few extra years without estrogen. The opposite seems true for women who go through menopause later, as more years of estrogen exposure may actually increase the risk for breast cancer.

    See the connection? More estrogen equals more risk, according to current research.

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