Zoledronic Acid Found to Improve Breast Cancer Outcomes

Women, who took Zoledronic acid (a bisphosphonate) in a recent trial, were found to have a 36% reduction of breast cancer recurrence when compared to a group who did not take the drug. Zoledronic acid is currently used to treat patients with bone metastasis, and was recently approved for osteoporosis treatment in post -menopausal women.

Zoledronic acid is marketed under the names Zometa and Reclast. The benefit proved significant in an Austrian trial of 1803 premenopausal women who showed improvement in all events associated with breast cancer spread and recurrence.

The anti-cancer effect of bisphosphonates has been previously studied, but results of studies have been inconsistent. Lead investigator, lead investigator Michael Gnant, MD, professor of surgery at the Medical University of Vienna and president of the Austrian Breast and Colorectal Cancer Study Group (ABCSG) says, "this is the first study to translate these effects into a clinical benefit".

Comparison was made among women with early pre-menopausal breast cancer with estrogen-receptor and/or progesterone-receptor positive tumors. Five percent of the women received chemotherapy prior to surgical removal of the primary tumor. None received chemotherapy afterwards, but were treated with ovarian suppression hormone (luteinizing hormone-releasing hormone) combined with tamoxifen or Arimidex. One group also received 4 mg. of intravenous Zoledronic acid every six months for three years. After five years, the outcomes were measured.

More studies are needed before zoledronic acid receives widespread recommendations. Pre-menopausal women with hormone responsive early breast cancer, who are receiving endocrine treatment should receive the drug, a point emphasized by breast cancer expert Eric Winer, MD, from Harvard Medical School, in Boston, Massachusetts, who moderated the American Society of Clinical Oncology 44th Annual Meeting's press conference where the study results were presented. Martine Piccart-Gebhart, MD, PhD, from the Institut Jules Bordet, in Paris, said: "This is not a practice-changing trial -- yet!" There are still several questions that need to be answered, and there is a need for confirmation from other trials "before we can recommend widespread use of zolendronic acid in routine care," she said. "I am convinced that we have to wait." Dr. Piccart-Gebhart is an internationally renowned breast cancer specialist.

The study lends support that younger women with early breast cancer, who are at low or moderate risk for disease progression, may not need treatment with chemotherapy. Drugs that suppress cancer-promoting hormones in women include Tamoxifen and aromatase inhibitors. Each works differently. Studies are ongoing to compare the benefits of giving Tamoxifen or aromatase inhibitors, either separately or together to enhance breast cancer outcomes. The role of these drugs has remained unclear.

Abstract; http://www.abstract.asco.org/AbstView_55_35897.html