Hormone therapy for breast cancer
Hormonal therapy - breast cancer; Hormone treatment - breast cancer; Endocrine therapy; Hormone-sensitive cancers - therapy; ER positive - therapy; Aromatase inhibitors - breast cancer
Hormone therapy to treat breast cancer uses drugs or treatments to lower levels or block the action of female sex hormones (estrogen and progesterone) in a woman's body. This helps slow the growth of many breast cancers.
Hormone therapy makes cancer less likely to return after breast cancer surgery. It also slows the growth of breast cancer that has spread to other parts of the body.
Hormone therapy can also be used to help prevent cancer in women at high risk for breast cancer.
It is different from hormone therapy to treat menopause symptoms.
Of all the different types of cancers, breast cancer is one of the most talked about, and with good reason. One out of every eight women will develop breast cancer sometime in their life. That's why every woman should be thinking about how to protect herself from this disease. Breast cancer is cancer that forms in the breast. Usually, it begins in the tubes that transport milk from the breast to the nipple. If the cancer spreads to other parts of the breast or body, it's called invasive breast cancer. Some breast cancers are more aggressive, growing more quickly than others. Although women are 100 times more likely to develop breast cancer, men can also get the disease because they do have breast tissue. You're more likely to get breast cancer if you're over 50, you started your periods before age 12, or you have a close family member with the disease. Drinking more than a couple of glasses of alcohol a day and using hormone replacement therapy for several years also may increase your risk. The telltale sign of breast cancer is a lump in your breast or armpit. You may also notice a change in the shape, size, or texture of your breast, or have fluid coming from your nipple when you're not breastfeeding. If you notice any changes in your breasts, call your doctor. You'll probably need to have an imaging scan, such as a mammogram, MRI, or ultrasound. A piece of tissue may be removed from your breast, called a biopsy. With these tests, your doctor can tell whether you have breast cancer, and if so, determine whether or not it has spread. So, how do we treat breast cancer? That really depends on the type of cancer, and how quickly it's spreading. Your doctor may recommend that you have the cancer removed with surgery. Sometimes it's enough just to remove the lump. That's called a lumpectomy. In other cases, the doctor will need to remove the entire breast to get rid of all the cancer or prevent it from coming back. That's called a mastectomy. Other treatments for breast cancer include chemotherapy, medicines that kill cancer cells, and radiation therapy, which uses energy to destroy cancer. Women whose cancer is fueled by the hormone estrogen may receive hormone therapy to block the effects of estrogen on their cancer. Today's breast cancer treatments are better than ever. Many women who have breast cancer go on to live long, healthy lives. The outlook really depends on how fast the tumor is growing, and how far it has spread. That's why it's so important to report any changes in your breasts to your doctor as soon as you notice them. Women who are at an especially high risk for breast cancer because of their family history can talk to their doctor about taking medicine or even having surgery to reduce their risk.
Hormones and Breast Cancer
The hormones estrogen and progesterone make some breast cancers grow. They are called hormone-sensitive breast cancers. Most breast cancers are sensitive to hormones.
Estrogen and progesterone are produced in the ovaries and other tissues such as fat and skin. After menopause, the ovaries stop producing these hormones. But the body continues to make a small amount.
Hormone therapy only works on hormone-sensitive cancers. To see if hormone therapy may work, doctors test a sample of the tumor that has been removed during surgery to see if the cancer might be sensitive to hormones.
Hormone therapy can work in two ways:
- By blocking the estrogen from acting on cancer cells
- By lowering estrogen levels in a woman's body
Drugs That Block Estrogen
Some drugs work by blocking estrogen from causing cancer cells to grow.
Tamoxifen (Nolvadex) is a drug that prevents estrogen from telling cancer cells to grow. It has a number of benefits:
- Taking Tamoxifen for 5 years after breast cancer surgery cuts the chance of cancer coming back by half. Some studies show that taking it for 10 years may work even better.
- It reduces the risk that cancer will grow in the other breast.
- It slows the growth and shrinks cancer that has spread.
- It reduces the risk of getting cancer in women who are high risk.
Other drugs that work in a similar way are used to treat advanced cancer that has spread:
- Toremifene (Fareston)
- Fulvestrant (Faslodex)
Drugs That Lower Estrogen Levels
Some drugs, called aromatase inhibitors (AIs), stop the body from making estrogen in tissues such as fat and skin. But, these drugs do not work to make the ovaries stop making estrogen. For this reason, they are used mainly to lower estrogen levels in women who have been through menopause (postmenopausal). Their ovaries no longer make estrogen.
Premenopausal women can take AIs if they are also taking drugs that stop their ovaries from making estrogen.
Aromatase inhibitors include:
- Anastrozole (Arimidex)
- Letrozole (Femara)
- Exemestane (Aromasin)
Lowering Estrogen Levels From the Ovaries
This type of treatment only works in premenopausal women who have functioning ovaries. It can help some types of hormone therapy work better. It is also used to treat cancer that has spread.
There are three ways to lower estrogen levels from the ovaries:
- Surgery to remove the ovaries
- Radiation to damage the ovaries so they no longer function, which is permanent
- Drugs such as goserelin (Zoladex) and leuprolide (Lupron) that temporarily stop the ovaries from making estrogen
Any of these methods will put a woman into menopause. This causes symptoms of menopause:
- Hot flashes
- Night sweats
- Vaginal dryness
- Mood swings
- Loss of interest in sex
Drug Side Effects
The side effects of hormone therapy depend on the drug. Common side effects include hot flashes, night sweats, and vaginal dryness.
Some drugs can cause less common but more serious side effects, such as:
- Tamoxifen. Blood clots, stroke, cataracts, endometrial and uterine cancers, mood swings, depression, and loss of interest in sex.
- Aromatase inhibitors. High cholesterol, heart attack, bone loss, joint pain, mood swings, and depression.
- Fulvestrant. Loss of appetite, nausea, vomiting, constipation, diarrhea, stomach pain, weakness, and pain.
Weighing the Options
Deciding on hormonal therapy for breast cancer can be a complex and even difficult decision. The type of therapy you receive may depend on whether you have gone through menopause before treatment for breast cancer. It also may depend on whether you want to have children. Talking with your health care provider about your options and the benefits and risks for each treatment can help you make the best decision for you.
American Cancer Society website. Hormone therapy for breast cancer.
Henry NL, Shah PD, Haider I, Freer PE, Jagsi R, Sabel MS. Cancer of the breast. In: Niederhuber JE, Armitage JO, Kastan MB, Doroshow JH, Tepper JE, eds. Abeloff's Clinical Oncology. 6th ed. Philadelphia, PA: Elsevier; 2020:chap 88.
National Cancer Institute website. Hormone therapy for breast cancer.
Rugo HS, Rumble RB, Macrae E, et al. Endocrine therapy for hormone receptor-positive metastatic breast cancer: American Society of Clinical Oncology Guideline. J Clin Oncol. 2016;34(25):3069-3103. PMID: 27217461
Last reviewed on: 9/24/2019
Reviewed by: Todd Gersten, MD, Hematology/Oncology, Florida Cancer Specialists & Research Institute, Wellington, FL. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.