What medications are generally used to treat breast cancer?
SERMs (selective estrogen-receptor modulators): These drugs bare a chemical resemblance to the hormone estrogen. Many breast cancers are "estrogen-dependent," meaning that they depend on estrogen in order to survive and reproduce. Because SERMs mimic estrogen, they are able to bind to estrogen receptors in breast cancer cells. By binding to these receptors, they block estrogen from breast cancer cells, thereby starving the cancer cells. Tamoxifen (brand name, Nolvadex)
is currently the most commonly prescribed SERM. Tamoxifen is approved by the U.S. Food and Drug Administration (FDA) to help treat both early and advanced stages of breast cancer. Recently, tamoxifen also received FDA approval for use in post-menopausal women at high risk of breast cancer after a large clinical trial showed that tamoxifen could reduce the risk of breast cancer by 49%. The drug Fareston (generic name, toremifene) is another SERM used to treat advanced breast cancer. Another SERM, Evista (generic name, raloxifene) is used to treat osteoporosis, a degenerative bone disease. However, a large clinical trial called STAR (Study of Tamoxifen and Raloxifene) is currently underway to investigate whether Evista (raloxifene) is as effective as tamoxifen in preventing breast cancer and whether it should be labeled for that use as well. Researchers are also investigating another SERM called arzoxifene for the treatment of breast cancer. Arzoxifene is made by the same company as raloxifene (Eli Lilly and Company) and is described to be a next-generation SERM. The drug is currently in Phase III clinical trials.
Aromatase inhibitors: These drugs work by binding to the body’s aromastase enzyme, an enzyme responsible for producing estrogen. Many breast cancer cells depend on estrogen to grow and multiply quickly. Once the aromatase inhibitor has binded to the aromastase enzyme, estrogen cannot be produced by the enzyme. This lack of estrogen starves cancer cells, preventing them from growing and dividing. There are several aromatase inhibitors that are used to help treat advanced breast cancer including: aromasin (generic name, exemestane), femara (generic name, letrozole), arimidex (generic name, anastrozole), megace (generic name, megestrol). Recent studies suggest that some aromatase inhibitors may be more effective than tamoxifen in treating advanced breast cancer or may be useful after patients become resistant to tamoxifen. For example, Femara was recently FDA approved as an initial treatment option in advanced breast cancer patients after data showed that Femara may work better than tamoxifen in some patients (i.e., slows the growth of cancer and improves survival time). Recent studies also show that both Arimidex and Femara many be more effective than Megace for treating breast cancer.
Biologic response modifiers: These drugs bind with certain proteins on breast cancer cells, preventing their growth. The drug Herceptin (generic name, trastuzumab) is a monoclonal antibody that attaches itself to HER2 (also written HER2/neu), a protein found on breast cancer cells. Approximately 30% of breast cancer patients have extra copies of the HER2 protein, which can signal more aggressive cancers. Herceptin binds to HER2 receptors on breast cancer cells, preventing them from growing and dividing. Herceptin is only indicated for breast cancer patients who overexpress the HER2 protein. Patients should be tested for HER2 expression to determine whether Herceptin is a viable treatment option.
Other hormonal therapies: Hormone therapies are used to treat breast cancers that are dependent on estrogen for survival. In addition to SERMs and aromatase inhibitors, there are several other hormonal therapies used to treat breast cancer. For example, the drug Zoladex (generic name, goserelin acetate) is a synthetic form of the body’s lutenizing hormone-releasing hormone (LHRH). Zoladex blocks the release of estrogen in breast cancer patients (and testosterone in prostate cancer patients), preventing breast and prostate cancer cells from growing. Another hormone therapy, Faslodex (generic name, fulvestrant), appears to be effective for women who have become resistant to tamoxifen, according to recent studies. Instead of binding to estrogen receptors in breast cancer cells like tamoxifen, Faslodex destroys estrogen receptors in cancer cells.
More information on breast cancer
What is breast cancer? - Breast cancer is cancer of breast tissue. Breast cancer starts in the cells of the breast. Breast tissue covers a larger area than just the breast.
What types of breast cancer are there? - Breast cancer is a type of uncontrolled growth of abnormal cells that can develop in one of several different areas of the breast.
What're the risk factors for breast cancer? - Risk factors for breast cancer include age, geographical variation, reproductive factors, inherited risk, previous breast disease.
What're the symptoms of breast cancer? - Symptoms of breast cancer include breast lump, breast discharge, nipple inversion, or changes in the skin overlying the breast.
How is breast cancer diagnosed? - The mainstay of breast cancer diagnosis is the triad of clinical history, physical examination and imaging (mammography or ultrasound).
What're the stages of breast cancer? - The stages of breast cancer depends on its size and the extent to which it has spread to other parts of the body.
What causes breast cancer? - The exact cause or causes of breast cancer remain unknown. Hormonal influences play a role in the development of breast cancer.
What're the treatments for breast cancer? - Treatment for breast cancer begins with a decision about the type of surgery. Breast implants is used for breast reconstruction.
What're the side effects of breast cancer treatment? - The type and extent of breast cancer treatment side effects vary depending on the particular treatment involved, its duration, and its dose.
How is breast cancer treated with surgery? - Surgery is the mainstay of therapy for breast cancer. A breast biopsy is the removal of breast tissue for examination by a pathologist.
What's the chemotherapy for breast care? - Chemotherapy is the use of anti-cancer drugs to treat cancerous cells. Chemotherapy involves being given a combination of anti-cancer medicines.
What's the radiation therapy for breast cancer? - Radiation therapy is often used to destroy any remaining breast cancer cells in the breast, chest wall, or axilla (underarm) area after surgery.
What's the hormone therapy for breast cancer? - Most breast cancer is sensitive to the female hormone oestrogen. Megestrol acetate is used for hormone treatment of advanced breast cancer.
What breast cancer medications are available? - Medications to treat breast cancer include selective estrogen-receptor modulators, aromatase inhibitors, biologic response modifiers.
Can breast cancer be prevented? - There is no known way to prevent breast cancer. But several preventive measures can be take to reduce risk of breast cancer.