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How Hormone Therapy Is Used to Treat Breast Cancer


Hormone therapy might be recommended by your doctor or breast specialist as an effective step against most kinds of early-stage breast cancers, or if you’re looking for alternatives to surgery, it may be a viable option. Before searching for a “breast surgeon near me,” learning more about this less-invasive and highly successful breast cancer treatment after diagnosis will help you understand why hormone or endocrine therapy may be the best choice for you.

Some hormones can promote cancer growth, especially cancers of the breast and prostate. Suppressing these effects can inhibit cancer growth, either by reducing the hormone levels or blocking the chemical receptors, which actively slows or stops cancer cells from reproducing. Your oncologist can use these as all or part of your treatment plan.

Let's look deeper into how hormones influence breast cancer, what medications are used in treatment, and what you can expect during hormone therapy for breast cancer.


Which Hormones Are Involved with Breast Cancer?

Hormones carry chemical messages throughout the body, stimulating cells to function, maintaining reproductive cycles, and also triggering cells to slow or reduce their activity. Estrogen and progesterone are natural female hormones that can stimulate the growth of hormone-sensitive types of breast cancer.


How Does Hormone Therapy Work in Breast Cancer Treatment?

The goal of hormonal or endocrine therapy is to prevent the cancer cells from receiving the hormones that cause them to grow. There are several strategies which may be combined to achieve this positive outcome:

  • Ablation - Blocking or suppressing ovarian hormone production
  • Oophorectomy - Removing the ovaries surgically to drastically reduce hormone production
  • Preventing the pituitary gland from signaling the ovaries to produce hormones.
  • Blocking the receptors on the cancer cells from binding with the hormone.


What Types of Breast Cancer Respond to Hormone Therapy?

While there are many types of breast cancer, for the purposes of this treatment, they are divided into two types:

  • Hormone-sensitive or hormone-dependent cancers, which respond well to hormone therapy because they rely on hormone stimulation for growth.
  • Hormone-insensitive cancers, which do not have hormone receptors (hormone receptor-negative), are not likely to respond to this treatment.

Your doctor will test cancer tissue samples to determine if it contains estrogen or progesterone receptors. With 80% of breast cancers testing estrogen receptor-positive,1 and most of these also being progesterone receptor-positive, hormone therapy offers a promising treatment option for most women with breast cancer.


What Medications Are Used in Hormone Treatment for Breast Cancer?

The particular medications that your breast specialist chooses will depend on which method or combination of strategies will be used to prevent the hormones from stimulating the tumor. Some of the FDA approved options include:

  • Aromatase inhibitors. These block an enzyme which is used by the ovaries for estrogen production and are most often used for postmenopausal women. Examples include anastrozole, letrozole, and exemestane.1
  • Selective estrogen receptor modulators (SERMs). By binding to estrogen receptors, SERMs block estrogen effects, but also serve to replace the missing estrogen in other body systems, protecting uterine health and bone strength. Tamoxifen and toremifene are examples.1
  • Other antiestrogens. There are other medications that block estrogen, one of which is fulvestrant. Fulvestrant not only binds the estrogen receptor but targets it for elimination.1 Goserelin and leuprolide are other FDA approved drugs also used in hormone therapy.


What to Expect During Hormone Therapy

There are hormone therapies available for women with all stages of breast cancer, and this treatment is often used after surgery to treat remaining cancer cells. The type and duration of hormone therapy needed are unique to your situation, past history, and age.

A specialized breast cancer oncologist will closely monitor how your body responds to the therapy and may need to make changes to the medications used based on how your body responds. Some factors to consider include:

  • Hormone therapy usually continues for at least five years, offering reduced risks of breast cancer recurrence.1
  • There are different medication choices, depending on whether the patient is premenopausal or postmenopausal. Tamoxifen, for example, is used before menopause, and anastrozole or letrozole is recommended for cancers developing after menopause.
  • Exemestane is often used for postmenopausal women who received tamoxifen in the past.
  • Switching to an aromatase inhibitor after two or three years of tamoxifen is also a newer approach for certain women, showing improved overall survival rates in research studies.1


Hormone Therapy in Advanced Breast Cancer Treatment

beautiful women of different ages with pink ribbons sitting on sofa in room

For more advanced stage cancers and those that have come back, hormone therapy can be an important tool in reaching full remission. Hormone treatments can help:

  • ER-positive breast cancer that recurs either in the breast, chest wall, or nearby lymph nodes after the original surgery or treatment.
  • Breast cancer that has spread after early treatment with antiestrogens, which may be treated with SERMS including tamoxifen or toremifene.
  • If initial treatment with tamoxifen causes advanced breast cancer to worsen, aromatase inhibitors, including exemestane, may be the answer for postmenopausal women.
  • Advanced or metastatic breast cancers, which can be treated with a targeted hormone approach using lapatinib in combination with letrozole for specific hormone-receptor-positive types of cancer.1
  • To reduce the size of ER-positive tumors prior to surgery, although this use of hormone therapy is still in the research phase, this approach has shown positive results for postmenopausal women.1


How Effective Is Hormone Therapy in Preventing Breast Cancer?

Research has shown that hormone therapy is also effective at preventing the development of breast cancer in those found to be at increased risk. Some of the exciting results which have led to approval of hormone therapy for the prevention of breast cancer include:1

  • Studies showing tamoxifen reduced the risk of invasive breast cancer in postmenopausal women at risk by approximately 50% when taken for five years. Long-term follow-up on this study showed that the beneficial effect lasted for at least 20 years.
  • Another large randomized trial showed that five years of therapy with the SERM raloxifene reduced cancer risk in postmenopausal women by approximately 38%.
  • A study of two aromatase inhibitors showed a reduction of risk for breast cancer of 50-65% for postmenopausal women who took the drugs exemestane and anastrozole for three years.


What Are the Side Effects of Hormone Therapy?

Because hormones are important to how the body functions, changing hormone levels often causes side-effects. Most are mild and can be managed with dosage adjustments or changes in the type of medication. Your oncology doctor will help you weigh the benefits of the therapy against the side-effects.

You should expect to experience some of these effects of treatment:

  • Hot flashes
  • Night sweats
  • Vaginal dryness
  • Loss of libido
  • Nausea and vomiting
  • Fatigue
  • Weight gain
  • Mood swings
  • Menstrual cycle changes

Rarer, long-term effects may include:

  • Bone loss or weakness; associated joint pain
  • Nutritional deficiencies; gastrointestinal distress
  • Increased risk of blood clots or stroke
  • Increased risk of heart attack or angina


Substances That Interfere with Hormone Therapy

female patient listening to doctor against pink awareness ribbon

During treatment, your breast doctor or oncologist will review the medications you are taking and alert you to possible interactions that could reduce the effectiveness of your treatment. Some of these include:

  • SSRIs – This category of antidepressants (including Prozac and Paxil) inhibits an enzyme that is necessary to metabolize tamoxifen and possibly other hormone medications. Another type of antidepressant can be prescribed which will not interfere with your therapy, most often sertraline (Zoloft), venlafaxine (Effexor), or citalopram (Celexa).
  • Cimetidine – A digestive acid reducer.
  • Quinidine – A medication that treats abnormal heart rhythms.


Menopausal Hormone Therapy

Estrogen therapy, or menopausal hormone therapy (MHT), is used to treat the symptoms of menopause. It should not be confused with hormone therapy for breast cancer; in fact, the two treatments have opposite goals and should not be used together.

MHT can stimulate an ER- or PR-positive cancer to grow and raises the levels of estrogen and progesterone in the bloodstream. Inform your doctors if you have had this or other hormone-stimulating therapies in the past. You should not continue taking any other hormone-influencing medications while undergoing hormone therapy for breast cancer treatment.


Evolving Optimal Care for Breast Cancer Patients

The latest advancements in breast cancer treatment are making a life-changing difference in the lives of women all over the world. Trusting your oncology doctor and team to provide you with immediate information and options allows you to take the next steps with confidence.

The accumulation of research for hormone therapy as an effective treatment for ER+ breast cancers has shown complete cures in the early stages of the disease2 and unquestionable positive results even in later stages. You should talk to your doctor about adding this powerful form of preventative and curative treatment to your fight against breast cancer.

Visit the top facilities in your area and choose your allies by their track record and genuine commitment to your wellbeing. In New York, there is no better team than the breast cancer oncologists at Crystal Run Healthcare. Contact us today for a consultation to find out if hormone therapy or another of our advanced treatment options is your best way forward.