(ChemotherapyAdvisor) – Further results from a randomized phase 3 study in more than 2,000 patients with breast cancer and bone metastases have shown that compared with zoledronic acid, denosumab was “superior” in reducing bone-related complications and maintained health-related quality of life (HRQoL), investigators reported in Clinical Cancer Research online August 14.

Previously, the study found denosumab (n=1,026) prolonged time to first on-study skeletal-related event (SRE) and reduced the risk of first SREs compared with zoledronic acid (n=1,020) in this patient population, Miguel Martin, MD, PhD, of the Hospital General Universitario Gregorio Marañón, Madrid, Spain, and colleagues reported.

The analyses reported in this study included “the proportion of patients with one or multiple on-study SREs, time to first radiation to bone, time to first SRE or hypercalcemia of malignancy, and change in HRQoL (functional assessment of cancer therapy–general),” they wrote.

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Results showed that 31% of patients in the denosumab arm had an on-study SRE vs 36% in the zoledronic acid arm (P=0.006). Incidence of first radiation to bone was 12% in the denosumab arm vs 16% in the zoledronic arm. “Denosumab prolonged the time to first radiation to bone by 26% vs zoledronic acid (HR, 0.74; 95% CI 0.59–0.94; P=0.012) and prolonged the time to first SRE or hypercalcemia of malignancy by 18% (HR, 0.82; 95% CI, 0.70–0.95; P=0.007),” Dr. Martin wrote.

Compared with zoledronic acid and regardless of baseline pain levels, 10% more patients had a clinically meaningful improvement in HRQoL with denosumab.

Patients assigned to denosumab had fewer acute phase reactions associated with a flu-like syndrome and fewer adverse events related to kidney dysfunction compared with those assigned to zoledronic acid.

“Our data indicate that denosumab should be the treatment of choice for the prevention of skeletal-related events and hypercalcemia in patients with breast cancer that has metastasized to the bone,” Dr. Martin said.