Breast cancer is a malignant disease that by far affects mainly women. It is the second most common type of cancer among American women. The disease causes symptoms such as a new breast lump or mass, swelling of all or part of a breast, skin irritation or dimpling, breast or nipple pain, nipple retraction, redness, scaliness, thickening of the nipple or breast skin, or nipple discharge other than breast milk. There are, however, a number of treatment options for breast cancer.

In 2016 alone, 61,000 non-invasive cases and 246,660 invasive cases of the disease are expected to be diagnosed in American women, according to the American Cancer Society.

Surgery and radiation therapy are considered local treatments, designed to address the cancer without harming the rest of the body, while systemic treatments, which are focused on treating cancer cells present anywhere in the body, include chemotherapy, targeted therapy, bone-directed therapy and hormone therapy.

Hormone Therapy Treatment

Women produce the hormones estrogen and progesterone mainly in their ovaries as they menstruate during their lifetime, but also in other tissue like fat and skin. Estrogen is responsible for the development and maintenance of female sex characteristics, while progesterone is necessary for menstruation and pregnancy.

However, they are also important in breast cancer, since there are hormone-sensitive breast cancer cells which have proteins and are called hormone receptors because they are activated by hormonal binding. When the receptors are activated, the expression of specific genes is altered and breast cancer cell growth is stimulated. A tumor with estrogen receptors is known as estrogen receptor-positive (ER-positive), estrogen-sensitive, or estrogen-responsive, while a tumor with progesterone receptors is called progesterone receptor-positive (PR- or PgR-positive).

According to the National Cancer Institute of the National Institutes of Health, about 70 percent of all breast cancers are ER-positive, and most of them are also PR-positive. Breast cancers can also be identified as ER-negative or PR- or PgR-negative when there is a lack of estrogen receptors or progesterone receptors, respectively.

Given the importance of hormones in breast cancer cell growth, hormone therapy is one of the treatment options for patients with breast cancer. The therapy is also called hormonal therapy and hormone treatment of endocrine therapy. It is designed to slow or stop the growth of hormone-sensitive tumors and works either by blocking the capacity of the body to produce hormones, or by blocking the function of the hormones. There are different types of hormone therapy.

“Because the ovaries are the main source of estrogen in premenopausal women, estrogen levels in these women can be reduced by eliminating or suppressing ovarian function. Blocking ovarian function is called ovarian ablation,” according to the National Cancer Institute. The drugs used for ovarian suppression are goserelin (Zoladex) and leuprolide (Lupron), while aromatase inhibitors like anastrozole (Arimidex) and letrozole (Femara) are drugs used in a different type of hormone therapy to block estrogen production.

“Aromatase inhibitors are used primarily in postmenopausal women because the ovaries in premenopausal women produce too much aromatase for the inhibitors to block effectively,” the NCI states on its website. “However, these drugs can be used in premenopausal women if they are given together with a drug that suppresses ovarian function.”

There are also drugs to block the effects of estrogen, the hormone which is able to stimulate the growth of breast cancer cells. These include selective estrogen receptor modulators (SERMs) like tamoxifen (Nolvadex), raloxifene (Evista), and toremifene (Fareston), and other anti-estrogen drugs, such as fulvestrant (Faslodex).

Benefits and Risks of Hormone Therapy

Hormone therapy is used in different ways, depending on the characteristics of the tumor and the needs of the patient. It can be used alone, before, or after other treatments and even to prevent the disease.

“Research has shown that women treated for early-stage ER-positive breast cancer benefit from receiving at least five years of adjuvant hormone therapy,” according to the NCI. “Adjuvant therapy is treatment given after the main treatment (surgery, in the case of early-stage breast cancer) to increase the likelihood of a cure.” There are also a number of drugs approved for the treatment of metastatic breast cancer, which means that it has spread to other parts of the body.

“The use of hormone therapy to treat breast cancer before surgery (neoadjuvant therapy) has been studied in clinical trials,” the NCI says. “The goal of neoadjuvant therapy is to reduce the size of a breast tumor to allow breast-conserving surgery. Data from randomized controlled trials have shown that neoadjuvant hormone therapies — in particular, aromatase inhibitors — can be effective in reducing the size of breast tumors in postmenopausal women. The results in premenopausal women are less clear because only a few small trials involving relatively few premenopausal women have been conducted thus far.”

There are, however, side effects associated with hormone therapy. Both the benefits and risks of the treatment depend on the drugs used. Hot flashes, night sweats, vaginal dryness, and alterations of the patient’s menstrual cycle are the most the common side effects. Other side effects specific to each drug include increased risk of blood clots, stroke, cataracts, endometrial and uterine cancers, and bone loss in premenopausal women. Tamoxifen can cause mood swings and loss of libido, while raloxifene may cause blood clots and stroke. 
Ovarian suppression drugs are associated with bone loss, mood swings, depression and loss of libido; aromatase inhibitors are associated with risk of heart attack, angina, heart failure, hypercholesterolemia, bone loss, joint pain, mood swings, and depression. The drug fulvestrant can cause gastrointestinal symptoms, loss of strength, and pain.
Note: Breast Cancer News is strictly a news and information website about the disease. It does not provide medical advice, diagnosis or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.
Inês holds a PhD in Biomedical Sciences from the University of Lisbon, Portugal, where she specialized in blood vessel biology, blood stem cells, and cancer. Before that, she studied Cell and Molecular Biology at Universidade Nova de Lisboa and worked as a research fellow at Faculdade de Ciências e Tecnologias and Instituto Gulbenkian de Ciência. Inês currently works as a Managing Science Editor, striving to deliver the latest scientific advances to patient communities in a clear and accurate manner.
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Inês holds a PhD in Biomedical Sciences from the University of Lisbon, Portugal, where she specialized in blood vessel biology, blood stem cells, and cancer. Before that, she studied Cell and Molecular Biology at Universidade Nova de Lisboa and worked as a research fellow at Faculdade de Ciências e Tecnologias and Instituto Gulbenkian de Ciência. Inês currently works as a Managing Science Editor, striving to deliver the latest scientific advances to patient communities in a clear and accurate manner.
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