A drug used to treat breast cancer that has spread to other parts of the body. It is used in postmenopausal women whose cancer is estrogen receptor positive (ER+) or when it is not known if the cancer is ER+ or estrogen receptor negative (ER-). Toremifene citrate blocks the effects of the hormone estrogen in breast tissue, which may help keep breast cancer cells from growing. It is a type of selective estrogen receptor modulator (SERM). Also called Fareston.