A regimen of less frequent bisphosphonate treatments appears to be just as effective as the standard bisphosphonate regimen in preventing skeletal events in patients with bone metastases from breast cancer after the first year of monthly administration, according to a recent study.
Bisphosphonates such as zoledronic acid reduce the occurrence of skeletal events such as bone pain, osteoporosis, spinal cord compression, and increased calcium levels in patients with bone metastases from breast cancer by limiting the activity of osteoclasts, the cells that break down bone to release calcium. There is also evidence that metastatic breast cancer cells are attracted to areas with active osteoclasts; therefore, limiting osteoclast activity with bisphosphonate treatment may decrease the risk of additional bone metastases.
The standard bisphosphonate treatment regimen for breast cancer patients with bone metastases is monthly intravenous infusions for life. To determine whether this is the optimum dosing schedule for bisphosphonates, a phase III clinical trial called OPTIMIZE-2 was conducted at The University of Texas MD Anderson Cancer Center and other institutions.
In the OPTIMIZE-2 study, 403 women with bone metastases from breast cancer who had completed 1 year of monthly treatment with zoledronic acid were randomly assigned to continue monthly treatment or receive treatment every 3 months. The study found no significant difference in efficacy between the two treatment arms; skeletal events occurred in 22% of patients treated monthly and 23% of those treated every 3 months.
The results of this trial, which could lead to a change in the standard of care for patients with bone metastases from breast cancer, were presented in June at the Annual Meeting of the American Society of Clinical Oncology by Gabriel Hortobagyi, M.D., a professor in the Department of Breast Medical Oncology. Dr. Hortobagyi said, “In general, in breast cancer we’re getting to the point where our patients are doing well enough that we can begin reducing the treatments they receive, as we’re likely over-treating the majority of our patients—and this study is an example of that.”
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OncoLog, July 2014, Volume 59, Issue 7