Analysis of Randomized Bisphosphonate Osteoporosis Trials Indicates No Reduction in Risk of Postmenopausal Breast Cancer
Observational studies have suggested a potential effect of bisphosphonate treatment for osteoporosis in reducing risk of breast cancer in postmenopausal women. However, an analysis of the randomized FIT trial of alendronate and HORIZON-PFT trial of zoledronic acid reported in JAMA Internal Medicine by Hue et al indicates the absence of such a benefit.
Study Details
In the FIT trial, 6,459 women aged 55 to 81 years were randomly assigned to daily oral alendronate or placebo for a mean follow-up of 3.8 years. In the HORIZON-PFT trial, 7,765 women aged 65 to 89 years were randomly assigned to annual intravenous zoledronic acid or placebo for a mean follow-up of 2.8 years. Women with recurrent breast cancer or who reported a history of breast cancer were excluded from analysis.
No Differences in Risk
There was no significant difference in the rate of invasive breast cancer in FIT for women receiving alendronate vs those receiving placebo (1.8% vs 1.5%, hazard ratio [HR] = 1.24, 95% confidence interval [CI] = 0.84–1.83, P = .28). There was also no difference after adjustment for age, smoking, previous hormone therapy use, body mass index, total hip bone mineral density, race, country/region, and age at menopause (HR = 1.17, 95% CI = 0.78–1.73, P = .45).
There was no significant difference between the zoledronic acid vs placebo groups in HORIZON-PFT (0.9% vs 0.8%, HR = 1.15, 95% CI = 0.70–1.89, P = .59) and no significant difference after in the adjusted analysis (HR = 1.15, 95% CI = 0.70–1.91, P = .58).
No significant difference in risk was observed when the bisphosphonate and placebo groups from both trials were pooled (1.3% vs 1.1%, HR = 1.20, 95% CI = 0.89–1.63, P = .24).
The investigators concluded: “These 2 randomized clinical trials do not support the findings from observational research. Contrary to the results from observational studies, we found that 3 to 4 years of bisphosphonate treatment did not decrease the risk of invasive postmenopausal breast cancer.”
Trisha F. Hue, PhD, MPH, of University of California, San Francisco, is the corresponding author for the JAMA Internal Medicine article.
Support for FIT was provided by Merck & Co, and support for HORIZON-PFT was provided by Novartis. Kristine E. Ensrud, MD, serves as a consultant on a data monitoring committee for Merck Sharp & Dohme.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
