Types of hormonal therapy

Hormonal therapy medicines are put into classes based on how they interact with the body’s natural hormones estrogen and progesterone. Some stop the body from making estrogen, while others prevent estrogen from helping the cancer cell grow.

Your doctor may recommend treatment with one hormonal therapy over another depending on:

• Whether you are premenopausal, perimenopausal or postmenopausal
• The stage of the cancer
• Possible side effects
• Your personal needs

In this section, you’ll learn more about the classes of hormonal therapies and some common breast cancer medicines within each class.

Estrogen blockers

Estrogen blockers prevent estrogen from causing breast cancer cells to grow. The medicines in this family are selective estrogen receptor modulators, SERMs, or estrogen receptor degraders (SERDs), also known as estrogen receptor agonists, or ERAs. These medicines work toward the same goal in slightly different ways.

SERMs prevent estrogen signals from getting to breast cancer cells. They are given as daily pills, and are some of the most common given to premenopausal and perimenopausal women with hormone receptor-positive breast cancer. Tamoxifen, a SERM, can be taken daily for 5 to 10 years after other treatment for early-stage breast cancer to prevent recurrence. Postmenopausal women can also take tamoxifen, usually before treatment with an aromatase inhibitor. In metastatic breast cancer, you may take SERMs as long as they keep the cancer from growing.

The SERMs are:

• Tamoxifen
• Toremifene citrate (Fareston)

Selective estrogen receptor downregulators (SERDs), also known as estrogen receptor antagonists (ERAs), stop the activity of estrogen on cancer cells to keep them from growing. SERDs can also break down or weaken estrogen receptors, making them inactive. SERDs are available for metastatic breast cancer and are given after other hormonal therapies stop working.

The SERDs FDA approved for metastatic breast cancer are:

• Fulvestrant (Faslodex)
• Elacestrant (Orserdu)

GnRH agonists

Gonadotropin-releasing hormone (GnRH) agonists, also known as luteinizing hormone-releasing hormone (LHRH) analogs, are medicines that reduce the amount of estrogen your body makes. They shut down your ovaries temporarily. When the ovaries stop making as much estrogen, hormone receptor-positive breast cancer cells can’t continue to grow. These medicines are usually paired with other forms of hormonal therapy. They may be used with the goal of preserving your fertility, though this method hasn’t yet been proved.

Medicines in this class are:

• Goserelin (Zoladex), Leuprolide (Lupron), and Triptorelin (Trelstar)

Oophorectomy

Oophorectomy is removing the ovaries with surgery so they can no longer make the estrogen that drives hormone receptor-positive breast cancer.

After menopause, your body stops making estradiol, the main estrogen produced by the ovaries. But your body still makes estrone, an estrogen created by converting a male sex hormone found in the adrenal glands, fat cells, and muscle. An enzyme called aromatase converts that hormone into estrogen.

Aromatase inhibitors, or AIs, are a class of medicines that interfere with the enzyme aromatase to reduce the risk of breast cancer returning in postmenopausal women with early-stage breast cancer. They are the standard hormonal therapy for postmenopausal women, and may be the first (primary) hormonal therapy your doctor prescribes. AIs are given as a daily pill, usually after surgery or chemotherapy. In this setting, they are taken for 5 years as the only hormonal therapy treatment, or for up to 5 years after up to 5 years of tamoxifen.

In metastatic breast cancer, aromatase inhibitors may be the first treatment given if you are postmenopausal and have hormone-positive disease. These medicines may be paired with other therapies or given alone. You may take one medicine for as long as it works at controlling the cancer. Your doctor may then recommend you try a different medicine.

The aromatase inhibitors are:

• Anastrozole (Arimidex and generic), Exemestane (Aromasin and generic), and Letrozole (Femara and generic)

Progestin hormonal therapy

Progestins are human-made medicines that act like the natural hormone progesterone. There is one FDA approved medicine in this family that is used to treat metastatic breast cancer or its symptoms:

• Megestrol acetate (Megace)