Interpreting results from oncology clinical trials: a comparison of denosumab to zoledronic acid for the prevention of skeletal-related events in cancer patients

BACKGROUND: Critically reviewing the design, endpoints, and results of clinical trials can be challenging to health care professionals. This paper will review the basic methods of presenting clinical outcomes in randomized trials and will focus on the number needed to treat (NNT) concept. NNT will then be applied to the case of bone-targeted therapies denosumab and zoledronic acid, which are used for the prevention of skeletal-related events (SREs) in a variety of disease sites. METHODS: A Medline search was performed to identify randomized trials comparing denosumab to zoledronic acid for the prevention of SREs in patients with advanced breast, prostate, and other cancer sites. The data were extracted, and point estimates for the primary and secondary trial endpoints were converted into the NNT parameter. RESULTS: NNT represents the number of patients that need to be treated with a new intervention in order to avoid one additional patient developing the event and is a powerful approach that can be used to make sense of numerical results from clinical trials. In patients with advanced breast, prostate, and other cancer sites, 18, 22, and 21 patients, respectively, would need to be treated with denosumab for at least 24 months to avoid one patient developing an SRE. CONCLUSIONS: The NNT approach is a simple and effective method to express the findings of randomized trials in a clinically meaningful way. In this analysis, the incremental benefits of denosumab would be realized when a minimum of 18 to 22 patients are treated for a prolonged duration. Clinicians would have to weigh the costs and benefits between denosumab and zoledronic acid when bone-targeted therapy is indicated.