What is hormonal therapy for breast cancer?
Hormonal therapy is a good option for women affected by breast cancer. When you are diagnosed with breast cancer, your physician will send a piece of the breast cancer tissue to be tested for hormone receptors that attach to estrogen and progesterone. Hormone receptors are proteins that are found on or in your cells and they act like switches that send messages to your cells to grow. The cancerous tissue will come back to either have or have not receptors for both or either estrogen (ER-positive, ER-negative) or progesterone (PR-positive, PR-negative). This information will assist your physician in determining if medications that decrease these hormones in your blood or block the receptors will work to decrease the growth or recurrence of your cancer. These medications can also be used for prevention in patients with genetic risk for breast cancer. If you are hormone receptor-negative these treatments will not work for your cancer.
How do hormonal therapies work to treat breast cancer?
Therapies that target hormones in your body are used primarily to affect estrogen by either decreasing the amount that is circulating or produced or by blocking its action on the cells. The most common medications are selective estrogen receptor modulators and aromatase inhibitors. These medications may be used alone or in combination with other chemotherapeutic agents to treat breast cancer. The use of the medications will be determined by your medical oncologist who will look at many variables related to your cancer diagnosis included the extent of disease, age, the risk for recurrence, and family history.
- Selective Estrogen Receptor Modulators (Nolvadex® tamoxifen) and Evista® (raloxifene) Fareston® (toremifene))- these medications are used to block the receptors that estrogen attaches to on the breast cells. Tamoxifen is often used in both pre and post-menopausal women, while raloxifene is used in postmenopausal women only.
- Antiestrogen (Faslodex® (fulvestrant))- attaches to estrogen receptor and targets receptor for destruction.
- Aromatase Inhibitors (Aromasin® (exemestane), Arimadex® (anastrozole) and Femara® (letrozole))- the enzyme aromatase converts androgens circulating in your body to estrogen- the aromatase inhibitor will prevent this conversion leading to less circulating estrogen in you body-most are used in postmenopausal women
Other therapies that may be used to stop estrogen production include LHRHs (luteinizing hormone-releasing hormones) which shut down your ovaries so that they stop producing estrogen especially if you are premenopausal. These medications include Lupron, Zoladex, and Trelstar. Your physician may also recommend having your ovaries prophylactically removed surgically.
Side Effects of Hormonal Therapy
Each medication may have an individual side effect profile. Some common side effects include:
- Hot flashes
- Bone and joint pain
- Loss of libido
- Mood swings
- Vaginal dryness
- Increased risk for blood clots
- Gastrointestinal upset
What is HER2?
Your pathology report may also have your HER2 status as well as your estrogen and progesterone status. Some patients with breast cancer (1 in every 5) will test positive for another receptor which may be overexpressed, known as HER2 (HER2/neu) which stands for human epidermal growth factor receptor 2. This overexpression causes the HER2 protein to be overproduced in patients and acts to promote cancer cell growth. Being positive for HER2 is not necessarily bad because this means there is actually a medication to target this and block the growth of cancer.
Her2 Positive Treatments
Most of the treatments that target HER2 are given intravenously over about a year’s time. Many patients will have a special port placed in their chest that will be used to access your body intravenously. The following medications are specifically available to treat HER2 positive patients:
- Herceptin® (trastuzumab)-this a monoclonal antibody that is a man-made to target the protein
- Kadcyla® (T-DMI or ado-trastuzumab emtansine)- a combination drug of Herceptin and a chemotherapeutic drug emtansine- these two drugs attach to one another to target the cancer cell
- Perjeta® (pertuzumab)- blocks cancer cells ability receive signals for growth
- Tykerb® (lapatinib) – blocks proteins that cause uncontrolled growth
What side effects may occur with HER2 targeted drugs?
Each drug has its specific side effect profile, however, some reported side effects may include:
- Heart damage including congestive heart failure- this often is short term but your doctor may order a special study known as an echocardiogram to follow your heart function
Questions to Ask
- What is my receptor status (ER, PR, and HER2) of my cancer?
- Will I need to take hormone therapy and for how long?
- What side effects should I expect from these medications?