Comparative Efficacy and Cost-Effectiveness of Denosumab Versus Zoledronic Acid in Cancer Patients with Bone Metastases

Background: This retrospective study compared the effectiveness and preliminary cost evaluation of denosumab and zoledronic acid (ZA) in patients with bone metastases from breast, prostate, and lung cancer. Methods: Patients treated with ZA or denosumab between January 2016 and August 2023 were analyzed. Outcomes included the incidence of skeletal-related events (SREs), time to first SRE, and cost per prevented SRE. An incremental cost-effectiveness analysis (ICER framework) was also performed, using prevention of SREs as the effectiveness outcome. Results: A total of 192 patients in the denosumab group and 239 in the ZA group were included. Denosumab significantly reduced the incidence of SREs compared with ZA (34.8% vs. 51.8%, p < 0.001). The median time to first SRE was longer with denosumab (34.5 vs. 29.1 months), but the difference was not statistically significant (p = 0.593). Stratified analyses showed significant benefit in breast (29.5% vs. 49.2%, p = 0.002) and prostate cancer (43.9% vs. 66.0%, p = 0.035), but not in lung cancer (39.1% vs. 45.9%, p = 0.484). Denosumab was more costly, with an additional USD 4686 per prevented SRE. Conclusions: Denosumab was more effective than ZA in reducing SREs, particularly in breast and prostate cancer patients, but it was associated with higher costs. These findings should be interpreted as preliminary due to the retrospective design and the absence of QALY-based outcomes.