The US Food and Drug Administration (FDA) recently granted the aromatase agent Arimidex® (anastrozole) full approval for the treatment of early hormone-positive breast cancer in postmenopausal women.
Breast cancer is diagnosed in over 200,000 women annually in the US alone. If breast cancer is caught and treated in early stages (prior to spread), cure rates are high with standard treatments. A large portion of patients have hormone-positive breast cancer-cancer that is stimulated to grow by the circulating female hormones estrogen and/or progesterone. Hormone therapy, often used to treat hormone-positive breast cancer, utilizes agents that reduce or prevent the ability of estrogen to stimulate the growth of cancer cells.
Tamoxifen (Nolvadex®) was historically the most commonly used agent for hormone-positive breast cancer. However, agents referred to as aromatase inhibitors are now being used more frequently. Tamoxifen binds to estrogen receptors in a cell, inhibiting production of estrogen’s growth-stimulatory effects. Aromatase agents actually prevent or reduce the production of estrogen in the body.
Arimidex is an aromatase agent that was previously approved for the treatment of advanced hormone-positive breast cancer in postmenopausal women and for early hormone-positive breast cancer in postmenopausal women following 5 years of treatment with tamoxifen.
Results from a large clinical trial (the ATAC trial) prompted the new approval, which allows Arimidex to be used immediately following surgery in early hormone-positive breast cancer in postmenopausal women. The ATAC trial, one of the world’s largest breast cancer treatment trials, included a comparison of Arimidex to tamoxifen in postmenopausal women with early hormone-positive breast cancer. At 5 years, patients who were treated with Arimidex experienced a 17%-reduced risk of a cancer recurrence compared to those treated with tamoxifen. Furthermore, treatment with Arimidex is well tolerated.
Postmenopausal women who have been diagnosed with early hormone-positive breast cancer may wish to speak with their physician regarding their individual risks and benefits of treatment with Arimidex.
Reference: AstraZeneca. ARIMIDEX® Gains Full FDA Approval for Adjuvant Treatment of Hormone Receptor-positive Early Breast Cancer in Postmenopausal Women. Available at: http://www.astrazeneca-us.com/modules/PRMS/display.asp?id=331244. Accessed September 2005.