Tamoxifen blocks the actions of estrogen in breast tissue and is used to treat estrogen receptor-positive breast cancer in adults and to lower the risk of breast cancer in women with DCIS or at high risk. Tamoxifen is an antiestrogen drug used in the treatment of breast cancer. It blocks the activity of estrogen, helping to stop the growth of some tumors. Tamoxifen is a drug used to treat breast cancer. It’s a type of hormone therapy, also known as endocrine therapy. It can be used by both premenopausal women (women who still have periods) and postmenopausal women (women whose periods have stopped). It can also be taken by men who have breast cancer. 2. How tamoxifen works. Tamoxifen is a medication that blocks the female hormone estrogen in the body. For more than 30 years, doctors have prescribed it to fight breast cancer tumors that depend on estrogen to grow. What Is Tamoxifen and How Does It Work? Tamoxifen is used to treat breast cancer that has spread to other parts of the body (metastatic breast cancer), to treat breast cancer in certain patients after surgery and radiation therapy, and to reduce the chances of breast cancer in high-risk patients. Tamoxifen (brand names: Nolvadex, Soltamox) is a medicine that blocks the effects of the hormone estrogen (called a selective estrogen receptor modulator, or SERM). Tamoxifen is a first choice among doctors for treating women who have not yet gone through menopause. Tamoxifen is a nonsteroidal SERM of the triphenylethylene family and was structurally derived from diethylstilbestrol -like estrogens and antiestrogens such as chlorotrianisene and ethamoxytriphetol. [103][104][105][106] Initially, clomifene was synthesized, and tamoxifen was developed subsequently. [103][105][106] Tamoxifen is closely related. Tamoxifen package insert / prescribing information for healthcare professionals. Includes: indications, dosage, adverse reactions and pharmacology. TAMOXIFEN (ta MOX i fen) prevents and treats breast cancer. It works by blocking the hormone estrogen in breast tissue, which prevents breast cancer cells from spreading or growing. Overview: Tamoxifen is commonly used to treat certain types of breast cancer. It is also used to lower your risk of invasive breast cancer and keep some breast cancers from coming back. It blocks.