According to results presented at the 2005 annual meeting of the American Society of Clinical Oncology (ASCO), the bisphosphonate Zometa® (zoledronic acid) may help prevent bone loss associated with early breast cancer treatment, including Femara (letrozole).
Breast cancer is diagnosed in approximately 250,000 women annually in the United States alone. If breast cancer is caught and treated early and prior to spread, standard treatment options yield high cure rates. A large fraction of patients have hormone-positive breast cancer-cancer whose growth is stimulated by the circulating female hormones estrogen and/or progesterone. Hormone therapy is often used to treat hormone-positive breast cancer; its agents reduce or prevent the ability of estrogen to stimulate growth of cancer cells. Femara, an aromatase agent, blocks the formation of estrogen in the body. It has recently been approved by the FDA for the treatment of early and advanced hormone-positive breast cancer.
One of the most common side effects of Femara in women is bone loss accompanied by an increase in bone fractures. The agent Zometa is a new generation bisphosphonate and has demonstrated the ability to prevent bone loss through biological processes. Zometa is FDA-approved for treating cancer that has spread to the bone. Studies show that Zometa reduces the incidence of bone fractures and/or bone loss.
A recent clinical trial including 93 cancer centers in the United States and Canada was conducted to evaluate treatment with Zometa at various times in women with early breast cancer who were receiving with Femara. Women in this study were treated initially with Femara plus Zometa or with Femara followed by Zometa at signs of a loss of bone density or a bone fracture. The women treated initially with Zometa showed a bone density increase in the spine and hip after one year. Conversely, bone density had decreased in the spine and hip in women who were given Zometa once they experienced bone loss or fracture. Furthermore, treatment with Zometa was safe and well tolerated.
Results suggest that early treatment with Zometa may help prevent bone loss and complications as a result of bone loss associated with the use of Femara in early breast cancer. Longer follow-up data will demonstrate the exact benefits of scheduling of Zometa in therapeutic regimens including Femara. Patients with hormone-positive breast cancer planning to undergo treatment with hormone therapy may wish to speak with their physician regarding their individual risks and benefits of participating in a clinical trial further evaluating Zometa or other novel therapeutic approaches. Two sources of information regarding ongoing clinical trials include the National Cancer Institute www.cancer.gov and www.cancerconsultants.com.
Reference: Brufsky A, Harker W, Beck J, et al. Zoledronic acid effectively inhibits cancer treatment-induced bone loss in postmenopausal women with early breast cancer receiving adjuvant letrozole: 12 mos BMD results of the Z-FAST trial. Proc Am Soc Clin Oncol . 2005;23:Abstract 533.