The United States Food and Drug Administration (FDA) recently approved the aromatase inhibitor Femara® (letrozole) for use in patients with postmenopausal early breast cancer who have finished 5 years of the anti-estrogen agent tamoxifen (Nolvadex®). Femara® is already approved for the treatment of advanced breast cancer in postmenopausal women.
Breast cancer is diagnosed in approximately 250,000 women annually in the United States alone. If breast cancer is caught and treated in early stages, prior to spread, cure rates remain high with standard treatment options. A large fraction of patients have hormone-positive breast cancer, which refers to cancer that is stimulated to grow from the circulating female hormones estrogen and/or progesterone. Hormone therapy is a type of therapy often used for treatment of hormone-positive breast cancer and utilizes agents that reduce or prevent the ability of estrogen to stimulate the growth of cancer cells. Tamoxifen is a hormone agent that has demonstrated anti-cancer activity for a treatment time period of 5 years, after which time its effectiveness is reduced.
The clinical trial that prompted the new FDA approval for Femara® included 5,100 postmenopausal women diagnosed with hormone-positive early-breast cancer. Patients had already been treated with tamoxifen and were then assigned either to further treatment with Femara® or placebo (inactive substitute). The average duration of treatment with Femara® was 2.5 years. Patients who were treated with Femara® had a 38% reduced risk of a cancer recurrence and a 39% reduced risk of death. Femara® is generally well tolerated, with a possible increase in the risk of osteoporosis (reduction in bone density), as well as muscle and joint pain.
Patients with hormone-positive, early breast cancer who have completed treatment with tamoxifen may wish to speak with their physician about their individual risks and benefits of further treatment with Femara®.