According to preliminary results recently presented from a large clinical trial, adjuvant therapy with the aromatase inhibitor Femara® (letrozole) improves cancer-free survival compared to the anti-estrogen agent Nolvadex® (tamoxifen) in the treatment of early, hormone-positive 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. Historically, Nolvadex® was the most commonly used agent for hormone-positive breast cancer; however, agents referred to as aromatase inhibitors have been emerging in the clinical forefront and are being used more frequently. Nolvadex® binds to estrogen receptors in a cell and inhibits estrogen from producing its growth-stimulatory effects. Aromatase agents actually prevent or reduce the production of estrogen in the body. Femara® has recently been approved by the FDA for the treatment of advanced hormone-positive breast cancer, as well as treatment for early hormone-positive breast cancer in patients that have completed 5 years of treatment with Nolvadex®.
The large clinical trial, referred to as the Breast International Group (BIG) 1-98 trial, included more than 8,000 postmenopausal women with early hormone-positive breast cancer. All patients underwent the surgical removal of their cancer and then were treated with either 5 years of Femara®, 5 years of Nolvadex®, 2 years of Femara® followed by 3 years of Nolvadex®, or 2 years of Nolvadex® followed by 3 years of Femara®. At a little over 2 years of treatment (26 months), patients being treated with Femara® have displayed a reduction in risk of developing a cancer recurrence and a reduction in the risk of death compared to those being treated with Nolvadex®. The risk of a cancer recurrence was reduced by 19% in patients being treated with Femara®. Importantly, the risk of a cancer recurrence at a site distant from the breast was reduced by 27% in the group of patients treated with Femara®, compared to those treated with Nolvadex®. In addition, the risk of death was reduced by 14% in patients treated with Femara®. The greatest effects of Femara® were seen in women who were at the highest risk of developing a recurrence (i.e. those with cancer spread to axillary (under the arm) lymph nodes, prior chemotherapy, etc.).
The researchers concluded that Femara® reduces the risk of cancer recurrences compared to Nolvadex® in patients with early-stage, hormone-positive breast cancer. Femara® is the first agent to produce these results as initial hormone therapy, or as hormone therapy following treatment with Nolvadex® in postmenopausal women with hormone-positive breast cancer. Follow-up will continue in this trial to help determine long-term effects of treatment with either Femara® or Nolvadex®, as well as the effects of different sequencing of the agents. Patients with hormone-positive, early breast cancer may wish to speak with their physician about their individual risks and benefits of treatment with Femara® or other aromatase agents.
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