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Breast Cancer

Hormone Therapy for Breast Cancer

Female hormones such as estrogen and progesterone, which help regulate body cycles such as menstruation, may play a role in the development of breast cancer. Hormone therapy is a treatment for breast cancers that are fueled by these hormones.

Why Hormone Therapy is Used in Breast Cancer Treatment

Certain breast cancers are stimulated by the female hormones estrogen or progesterone. Doctors refer to these cancers as estrogen receptor positive (ER-positive) or progesterone receptor positive (PR-positive). These types of cancer are also called hormone-sensitive breast cancer. Hormone therapy aims to slow or prevent cancer growth by blocking the body’s ability to produce hormones or by interfering with the effects of hormones on breast cancer cells. 

Types of Hormone Therapy Used for Breast Cancer

There are several strategies used to treat hormone-sensitive breast cancer, including selective estrogen receptor modulators, aromatase inhibitors, estrogen receptor downregulators, and gonadotropin releasing hormone analogs (ovarian suppression). These are often incorporated into the treatment plan with other breast cancer therapies, such as breast cancer surgery, chemotherapy, and radiation therapy. 

Selective Estrogen Receptor Modulators

Selective estrogen receptor modulators, also called SERMs, prevent breast cancer cells from binding to estrogen. They do this by sitting in the estrogen receptors in the breast tissue. When a SERM is in the estrogen receptor, there is no room for estrogen, therefore prohibiting it from attaching to the cell. 

The most commonly used SERMs are Tamoxifen (Nolvadex®) and Toremifene (Fareston®). Both of these drugs are taken by mouth, most often as a pill, and can be used to treat women both before and after menopause. 

Aromatase Inhibitors

Drugs called aromatase inhibitors (AIs) are used to block the activity of an enzyme called aromatase, which the body uses to make estrogen in the ovaries and other tissues. In most cases, aromatase inhibitors are primarily used among postmenopausal women. This is because the ovaries in premenopausal women produce too much aromatase for the inhibitors to block effectively. Common AIs include anastrozole (Arimidex®), letrozole (Femara®), and exemestane (Aromasin®). 

Estrogen Receptor Downregulators 

Estrogen receptor downregulators, or ERDs, block the effects of estrogen in breast tissue. Currently, fulvestrant (Faslodex®) is the only ERD available to treat hormone receptor positive breast cancer. Like the SERM drugs, fulvestrant sits in the estrogen receptors in breast cells. The difference, however, is that it is a pure antiestrogen. Additionally, when fulvestrant binds to the estrogen receptor, the receptor is targeted for destruction. 

Gonadotropin Releasing Hormone Analogs or Ovarian Suppression

Because most of the estrogen in premenopausal women is made by the ovaries, permanently removing or suppressing them can be an effective treatment. Suppressing ovarian function is called ovarian ablation, and this will allow the hormone therapies to work better. Ovarian ablation can be done surgically (oophorectomy) or medically (drugs). 

Side Effects of Hormone Therapy

Different hormone therapies have different side effects. Common side effects may include: 

  • Hot flashes and night sweats
  • Loss of sex drive
  • Irregular periods or spotting
  • Vaginal dryness or itching
  • Mood swings 
  • Loss of bone density
  • Joint and muscle pain
  • Fatigue 

Hormone therapy can also disrupt the menstrual cycle in premenopausal women. 

Can Hormone Therapy be Used to Reduce Breast Cancer Risk?

Most breast cancers are hormone receptor positive, and clinical trials have tested whether hormone therapy can be used to reduce the likelihood of breast cancer in women who have a higher risk of developing the disease. At this time, Tamoxifen® and Raloxifene® are the only two drugs approved by the FDA to reduce the risk of breast cancer development, however, other studies are underway.

Personalized Breast Cancer Treatment on the Peninsula, Southside, Western Tidewater, and Northeast North Carolina

If you were recently diagnosed with breast cancer, the first step is to schedule a consultation with an oncologist. If you are located on the Peninsula, Southside, Western Tidewater, or Northeast North Carolina, we offer personalized treatment plans and second opinions on breast cancer treatment. Choose one of our cancer center locations in Chesapeake, Elizabeth City, Newport News, Norfolk, Suffolk (Harbour View and Obici), Virginia Beach, and Williamsburg to schedule a consultation.