toremifene

Definition

Toremifene, also known as Fareston, is a synthetic compound similar to estrogen. It mimics the action of estrogen on the bones and uterus, but blocks the effects of estrogen on breast tissue.

Purpose

Toremifene is used as adjuvant hormone therapy immediately after surgery in early stages of breast cancer and also to treat advanced metastatic breast cancer (stages III and above) in postmenopausal women. Post-menopausal women at high risk of developing breast cancer may take toremifene to reduce risk.

Description

Toremifene is similar to tamoxifen in structure and action. Toremifene can be given as sole treatment, but it is often given in combination with other chemotherapeutic drugs.

Toremifene belongs to a family of compounds called antiestrogens. Antiestrogens are used in cancer therapy by inhibiting the effects of estrogen on target tissues. Estrogen is a steroid hormone secreted by granulosa cells of a maturing follicle within the female ovary. Depending on the target tissue, estrogen can stimulate the growth of female reproductive organs and breast tissue, play a role in the female menstrual cycle, and protect against bone loss by binding to estrogen receptors on the outside of cells within the target tissue. Antiestrogens act selectively against the effects of estrogen on target cells in a variety of ways, thus they are called selective estrogen receptor modulators (SERMs).

Toremifene selectively inhibits the effects of estrogen on breast tissue, while mimicking the effects of estrogen on bone (by increasing bone mineral density) and uterine tissues. The former makes toremifene an excellent therapeutic agent against breast cancer. Although researchers are unclear of the precise mechanism by which toremifene kills breast cancer cells, it is known to compete with estrogen by binding to estrogen receptors, therefore limiting the effects of estrogen on breast tissue. Toremifene may also be involved in other anti-tumor activities affecting oncogene expression, promotion of apoptosis and growth factor secretion.

Recommended dosage

Toremifene is taken orally, and the recommended dose is usually 40 to 60 milligrams once a day, although larger doses are sometimes prescribed. If a dose is missed, patients should not double the next dosage. Instead, they should return to their regular schedule and contact their doctor.

Content licensed from:

Author Info: Sally C. McFarlane-Parrott, The Gale Group Inc., Gale, Detroit, Gale Encyclopedia of Cancer, 2002

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