Tamoxifen
Tamoxifen is used to treat breast cancer in both pre- and postmenopausal women with advanced or metastaticThe term for a cancer that has spread beyond its point of origin. Metastatic disease is responsible for the majority of cancer deaths. breast cancer. It is also given to reduce the risk of invasive breast cancer in women who have been treated for ductal carcinomaCancer of epithelial cells, the cells that cover the outside and inside of body surfaces. This is the most common form of cancer. in situFrom the Latin, (DCIS). Tamoxifen is taken in tablet form. Patients that are taking tamoxifen to reduce the risk of invasive breast cancer, whether in a high risk population or who have a history of DCIS, will normally receive this treatment for a period of 5 years.1
Tamoxifen (Nolvadex®) is a molecule that competes with estrogenA steroid sex hormone. Estrogen's structure is closely related to cholesterol. Produced by the ovaries, estrogen has effects on the reproductive, cardiovascular and skeletal systems. Estrogen is also a growth factor for some types of cells, including breast cells. Inhibitors of estrogen function such as tamoxifen and arimidex are used to block the growth effects of estrogen. See also, estrogen receptor. for binding sites on estrogen receptors in certain tissues of the body. This competition with estrogen limits cell growth in some tissues, as it leads to the inhibition of transcriptional and signaling processes that are required for cell growth.1
The diagram above shows the 3D structure of 4-Hydroxytamoxifen.
Common side effects include a variety of menopausal symptoms: hot flashes, vaginal discharge or bleeding, menstrual irregularities. Other side effects include: fluid retention, headache, lethargy, skin rash and myelosuppressionThe decreased activity of the blood cell precursors located in the bone marrow. Both red and white blood cells in the bloodstream originate from these cells which are often short-lived and are replaced constantly by rapidly dividing precursor stem cells. Chemotherapy agents, radiation and many other cancer treatments are designed to attack rapidly dividing cells and inhibit the activity of these normal bone marrow cells. Several side effects of cancer treatment, such as anemia and a decreased ability to fight infections (immunosuppression) are due to the effects of these treatments on bone marrow cells..1
Patients being treated with tamoxifen are also at increased risk for blood clots in the legs and lungs, and also for strokes. These events are serious but are rare. Tamoxifen may also increase the risk of endometrialRefers to the endometrium, the inner lining of the uterus. The endometrium is a common site of cancer. cancer in patients receiving treatment that have not undergone a hysterectomy. Patients should not become pregnant while taking tamoxifen or within 2 months after treatment is stopped as the drug could harm the unborn child. Also, oral contraceptivesA device used to prevent pregnancy. Oral contraceptives used by women contain different mixtures of hormones such as estradiol and progesterone. should not be used while taking tamoxifen. Therefore other forms of birth control must be used, such as condom or diaphragm.1, 2
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