Zoledronic Acid Benefit in Breast Cancer: Data Published in NEJM

February 11, 2009 — Details of a study showing a beneficial effect of zoledronic acid on breast cancer outcomes are published in the February 12 issue of the New England Journal of Medicine.

This was one of the first studies to show that the drug, a bisphosphonate used for osteoporosis and bone metastases, also has a benefit in breast cancer. Preliminary results were presented at the American Society of Clinical Oncology (ASCO) meeting last year, and reported by Medscape Oncology at the time.

The finding comes from the Austrian Breast and Colorectal Cancer Study Group (ABSCG)-12 trial, and the first author is Michael Gnant, MD, from the Medical University of Vienna, in Austria. The study was funded by AstraZeneca, which markets anastrozole (Arimidex), and Novartis, which markets zoledronic acid (Zometa, Reclast).

The trial involved 1803 premenopausal women with estrogen-responsive early breast cancer. After surgery, they received standard treatment, composed of ovarian suppression with goserelin plus adjuvant endocrine treatment with either tamoxifen or the aromatase inhibitor anastrozole for a period of 3 years. The results showed no difference in the outcomes between tamoxifen and anastrozole groups.

In addition, half of the women were randomized to receive zoledronic acid 4 mg intravenously every 6 months, also for 3 years.

The addition of zoledronic acid significantly improved disease-free survival. It resulted in an absolute reduction of 3.2% and a relative reduction of 36% in the risk for disease progression (hazard ratio [HR], 0.64; 95% confidence interval [CI], 0.46 to 0.91; P = .01).