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Hormonal Therapy

Reviewed by: M. Tish Knobf, PhD, RN, FAAN, AOCN

Updated January 11, 2013

Some cancers rely on the hormones estrogen and progesterone to grow and survive. These hormones occur naturally in your body. If you deprive these types of cancers of hormones, the cancer cells’ growth slows or stops.

Hormonal therapy targets the cancer cells that have estrogen and progesterone receptors. Your pathology report will say whether the breast cancer is estrogen receptor-positive, progesterone receptor-positive, or both. If the cancer uses these hormones to grow, it may respond to this type of therapy.

In DCIS and early-stage breast cancer, you are likely to receive hormonal therapy as adjuvant therapy, treatment given after primary therapy with surgery, chemotherapy or radiation, to help prevent the cancer from coming back. In metastatic (stage IV) breast cancer you may receive hormonal therapy alone or with other medicines to treat the cancer. If a hormonal therapy stops working against the cancer, your doctor may switch you to another.

Importance of Menopausal Status

Your menopausal status impacts what kind of hormonal therapy will work best for you.

If you are premenopausal, you still have your period. During premenopause, your ovaries make most of the body’s estrogen and you are able to become pregnant. If you have hormone-sensitive breast cancer, the high levels of estrogen produced by your ovaries help encourage the breast cancer cells to grow. Your healthcare team will recommend hormonal therapies that slow or stop estrogen from being made and reduce your risk of recurrence.

If you are perimenopausal, you are in-between having your period and stopping your period entirely. You might only have your period a few times a year. Perimenopause happens as you age and your ovaries slow down and make less estrogen, usually a few years before menopause.

If you are postmenopausal, you stopped having your period for 12 months in a row. In postmenopause, your ovaries stop making estradiol, the most active estrogen, and you can no longer become pregnant. Still, your body continues to make estrone, an estrogen created by converting the male sex hormone androstenedione from the adrenal glands, fat cells and muscle. The enzyme aromatase converts that hormone into estrogen. Your healthcare team will likely recommend aromatase inhibitors as your first hormonal therapy, because they target the aromatase that creates estrogen.

Hormonal Therapy Basics

Hormonal therapy blocks the estrogen that cancer cells need to grow. It blocks estrogen receptors, reducing the amount of estrogen the body makes, or lessening the number of hormone receptors on cancer cells.

The most common hormonal therapies are:

You may receive hormonal therapy after surgery, chemotherapy or radiation, or your doctor may recommend you take it at the same time as other treatment, such as targeted therapies for HER2 positive disease. In some cases, you may take hormonal therapy to shrink tumors before surgery.

Depending on the type of hormonal therapy, you may take it as a pill, as liquid, or by injection. Another option is oophorectomy, surgery to remove the ovaries. If you have oophorectomy, you may receive additional hormonal therapy after.

The standard course of hormonal therapy treatment is daily for five years. Be sure to ask your providers how you will receive treatment, how often you will take it, and why they recommend each combination.

Because hormonal therapy can change the amount of estrogen in your body or the way your ovaries work to produce estrogen, they impact your fertility. If you are premenopausal, talk with your healthcare team about ways to protect fertility while on hormonal therapy, and see LBBC’s resources on family planning after breast cancer.

Hormonal Therapy Options by Menopausal Status

For premenopausal women

Therapies often recommended for premenopausal women are:

For postmenopausal women

Therapies often recommended for postmenopausal women are:

For perimenopausal women

Therapies often given to perimenopausal women are:

Options available for women with metastatic breast cancer only:

Hormonal Therapy Options Defined

Selective Estrogen Receptor Modulators (SERMs)

The family of medicines known as selective estrogen receptor modulators works by blocking estrogen from reaching estrogen receptors on breast cancer cells. One SERM, tamoxifen, is standard treatment for premenopausal and perimenopausal women with hormone-sensitive breast cancer. Another, toremifene (Fareston), may be used if you are postmenopausal and have hormone-sensitive, metastatic breast cancer.


Tamoxifen is standard treatment for premenopausal and perimenopausal women with hormone-sensitive breast cancer. Postmenopausal women may also take tamoxifen, although the recommended first treatment today is aromatase inhibitors. Studies show breast cancer deaths to be down 30 percent in women 15 years beyond the start of tamoxifen treatment.

How it’s given

Tamoxifen is taken as a 20mg daily pill for five years, if you are premenopausal. If you are postmenopausal, tamoxifen may be taken for two to three years in sequence with an aromatase inhibitor. Tamoxifen is also available in liquid form as tamoxifen citrate (Soltamox).

Possible side effects

Hot flashes, night sweats, fatigue, vaginal dryness, vaginal discharge, mood changes or depression, nausea, dry skin, bone pain, headache, hair thinning, loss of sexual interest, constipation, weight gain.

Rare but serious side effects

Blood clots, stroke, uterine (endometrial) cancer.

Other medicines that may impact tamoxifen

Antidepressants such as fluoxetine hydrochloride (Prozac), paroxetine hydrochloride (Paxil), and sertraline hydrochloride (Zoloft); arthritis medicines such as Celebrex; and antacids such as Tagamet and Zantac or antihistamines like Atarax and Benedryl.

It is not yet known if these medicines impact tamoxifen’s anti-cancer effects. Be sure to tell your healthcare team about any medicines or supplements you take, so that you can make changes if needed.

Additional benefits

In addition to reducing the risk of breast cancer returning, tamoxifen can lower cholesterol and lessen bone loss in postmenopausal women during treatment.

Toremifene (Fareston) 

Toremifene is closely related to tamoxifen and may be used if you are postmenopausal and have hormone-sensitive metastatic breast cancer or do not know the cancer’s hormone-receptor status.

How it’s given

Toremifene is taken as a 60mg daily pill.

Possible side effects

Dizziness, headache, dry eyes, double vision, tiredness, hot flashes, sweating, loss of appetite, nausea, vomiting, bone and joint tenderness or pain, swelling, loss of coordination.

Possible serious side effects

Clouding of the eyes; confusion; uneven or pounding heartbeat; dry mouth or extreme thirst; fever; chills; cough; sore throat; body aches; swelling of the hands, ankles or feet; vaginal bleeding.

Other medicines that may impact toremifene

Some prescription and over-the-counter medicines may interact with toremifene, or cause its side effects to worsen. Let your doctor know about all medicines and supplements you take, to be sure toremifene works against the cancer as well as possible.

Ovarian Suppression: LHRH agonists

The amount of estrogen your body makes can be reduced by using medicines that shut down the ovaries for a time. These medicines are called luteinizing hormone-releasing agonists (LHRH agonists). LHRH agonists are believed to protect the ovaries of premenopausal women during chemotherapy, but the full benefit is still unknown. LHRH agonists are still under study. The LHRH agonists are:

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

Ask your doctors to be specific about what kind of ovarian suppression they recommend; some doctors may use “ovarian suppression” or “ovarian ablation” to mean the same thing. Ovarian ablation can also mean surgery to permanently remove your ovaries.

How they’re given

LHRH agonists are given as an injection once a month, every three months, or as an implant that lasts three months.

Possible side effects

Hot flashes, mood changes, vaginal dryness, loss of sexual interest, weight gain, headache, bone thinning, bone pain, insomnia, sweating, fatigue, joint and muscle aches.

Ovarian Ablation: Oophorectomy

Oophorectomy is surgery to permanently remove your ovaries. It causes surgical menopause and ends fertility. If you have an oophorectomy, you will no longer be able to become pregnant. Oophorectomy may be done in women of any menopausal status, but it is most often recommended if you are premenopausal.

Oophorectomy is often used in women who are at high risk for developing breast cancer because of BRCA1 or BRCA2 genetic mutations.

How it’s given

Oophorectomy is a one-time surgery. Your doctor may also recommend treatment with tamoxifen or an aromatase inhibitor.

Possible side effects

Permanent infertility, hot flashes, night sweats, mood changes, vaginal dryness, bone thinning, loss of sexual interest.

Aromatase Inhibitors (AIs)

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. The enzyme aromatase converts that hormone into estrogen.

Aromatase inhibitors area family of medicines that interfere with the enzyme aromatase to reduce therisk of breast cancer returning. The aromatase inhibitors are:

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

How they’re given

Aromatase inhibitors are given as a daily pill, taken for five years, or for two to three years if taken after two to three years of tamoxifen. AIs are often given after surgery or chemotherapy. They are the standard hormonal therapy for postmenopausal women, and may be the first (primary) hormonal therapy your doctor prescribes.

Possible side effects

Joint and bone pain, stiffness, bone thinning, nausea, vomiting, hot flashes, weakness, headache, vaginal dryness, loss of appetite, weight gain, insomnia, mood changes, constipation or diarrhea, dry skin, hair thinning, fatigue, nervousness, dizziness, vision changes, higher cholesterol, swelling, insomnia, vaginal bleeding.

Selective Estrogen Receptor Downregulators (SERDs)

Selective estrogen receptor downregulators, or SERDs, are a family of medicines that stop the activity of estrogen on cancer cells to keep them from growing. SERDs are only available for stage IV breast cancer and are given after other hormonal therapies stop working. The SERDs are:

  • Fulvestrant (Faslodex)
  • Megestrol Citrate (Megace)

How they’re given

SERDs are given either as an injection given every four weeks or as a daily pill, depending on the medicine your doctor recommends.

Possible side effects

Headache, back pain, nausea or vomiting, constipation, diarrhea, stomach pain, tiredness, weakness, swelling, bleeding between menstrual periods, hair loss, mood changes, rash, pain in the hand or wrist, trouble sleeping.

Possible serious side effects

Chest pain, shortness of breath, coughing up blood, extreme nausea, vomiting, dizziness or weakness, numbness or weakness on one side of the body, pain in the lower leg, rapid weight gain, sudden vision changes, headaches or trouble walking, unusual bleeding or bruising, and swelling of the hands, ankles or feet.

Under Study: Mammalian Target of Rapamycin Inhibitors (mTOR inhibitors)

The mammalian target of rapamycin, or mTOR, is a type of enzyme that helps control normal cell growth. In some cancers, mTOR works abnormally and encourages cancer cells to grow. Sometimes it directs nutrients to the cancer cells, helping them live longer.

mTOR inhibitors work to slow or stop mTOR’s function in the growth of cancer cells. So far, only one mTOR inhibitor, everolimus (Afinitor) is FDA-approved. It is given with the aromatase inhibitor exemestane (Aromasin). It has only been studied in postmenopausal women with hormone-sensitive, stage IV breast cancer.

How it’s given

Everolimus is taken as a daily pill.

Possible side effects

Acne, rash, change or loss of taste, constipation, diarrhea, stomach pain, loss of appetite, earache, headache, joint or muscle pain.

Possible serious side effects

Chest pain; trouble breathing; painful urination; dry mouth; extreme thirst, nausea or vomiting; symptoms of cold; uneven or fast heartbeat; tingling in the hands or feet; lightheadedness; fainting or dizziness; seizures; lumps in the armpit, neck or groin; pain in the groin, lower back or side; sores or ulcers on the mouth or lips; weight gain; swelling; unusual bleeding or bruising; yellow skin or eyes.

Remembering to Take Your Hormonal Therapy

Only about half of women prescribed hormonal therapy take the correct dose for the full recommended time. It is important to take your medicine every day, because your body makes hormones every day. There are many reasons you might find it hard to stick with hormonal therapy, but completing treatment as prescribed allows it to be as effective as possible and may reduce side effects.

The top reason women quit hormonal therapy early is because of side effects. We don’t know why some women experience difficult side effects, when other women taking the same medicine have mild or no problems.

Know that side effects are real. Your healthcare team has many tools to help you manage them. Please do not suffer in silence! Just because you are taking treatment does not mean you must have side effects. Start by:

  • Sharing your concerns with your providers. You may be able to switch to a medicine that works in a similar way, or they may suggest techniques to lessen the side effects
  • Considering a second opinion, if your doctor won’t discuss your concerns
  • Talking with other women who have taken hormonal therapy for ideas and advice

If you forget to take your hormonal therapy

  • Try keeping your pills in a place where you will see them every day
  • Take your pill when you do another daily activity, like brushing your teeth or having a morning coffee, to help remind yourself
  • Use a weekly pill organizer
  • Mark your calendar when you take your medicine
  • Set an alarm on a clock or cell phone for the same time every day
  • Take it at the same meal every day

If you have financial concerns

  • Ask your doctor if samples are available when you first start a medicine. This way you won’t have paid for a full prescription if you need to switch because of side effects
  • Tell your doctor you prefer generic medicines, which are usually cheaper than the brand-name
  • If your medicine is available by mail-order, you may be able to get several months for one co-pay
  • Be open with your healthcare providers if you have trouble with payments. Patient assistance programs are available

If taking hormonal therapy has an emotional impact

Each person has a different emotional response to hormonal therapy. It might feel empowering to you to take a daily pill. Or, you might see the treatment as an unhappy daily reminder of breast cancer. Your emotions—whether positive or negative—are a reasonable response to being in a situation you didn’t choose. If your feelings about hormonal therapy keep you from taking your medicine every day, consider: