(HealthDay News) — Data from two randomized controlled trials suggest that bisphosphonate use does not protect against postmenopausal breast cancer, according to research published online in JAMA Internal Medicine.
Trisha F. Hue, PhD, MPH, from the University of California in San Francisco, and colleagues examined the correlation between postmenopausal breast cancer incidence and bisphosphonate use.
Data were obtained from the Fracture Intervention Trial (FIT), involving 6,459 women who were randomly assigned to alendronate or placebo, and the Health Outcomes and Reduced Incidence With Zoledronic Acid Once Yearly-Pivotal Fracture Trial (HORIZON-PFT), involving 7,765 women, randomly assigned to annual intravenous zoledronic acid or placebo.
In both studies, the researchers examined the hazard ratio (HR) for incident breast cancer in the bisphosphonate group vs. the placebo group.
The researchers observed no significant between-group difference in the rate of breast cancer in FIT (1.5% in placebo group vs. 1.8% in alendronate group; HR=1.24; 95% CI, 0.84-1.83) or in HORIZON-PFT (0.8% in placebo group vs. 0.9% in zoledronic acid group; HR=1.15; 95% CI, 0.70-1.89).
When the data from FIT and HORIZON-PFT were pooled, there was no significant between-group difference noted (HR=1.20; 95% CI, 0.89-1.63).
“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,” the researchers wrote.
In an editor’s note, Joseph S. Ross, MD, MHS, commented on the study’s findings as well as discussed the differences between randomized clinical trials (RCTs) and observational studies.
“Whereas these findings highlight why it is so important for new therapies to be evaluated using RCTs, they also reinforce the importance of assessing the methodological rigor of observational studies before interpreting real-world effects,” he wrote.
“Whereas we all can remember examples of when RCTs and observational studies differed, less memorable are the even more numerous examples in which results were consistent. In the end, we should be open to all types of evidence and rely on rigorous clinical science to guide practice.”
One author disclosed financial ties to Merck Sharp & Dohme. FIT was funded by Merck and HORIZON-PFT was funded by Novartis.