Evaluation of the clinical benefit of long-term (beyond 2 years) treatment of skeletal-related events in advanced cancers with zoledronic acid.

BACKGROUND: Skeletal complications of malignant bone disease are common among patients with both solid tumors and multiple myeloma (MM). Zoledronic acid (ZOL; Zometa*) is an intravenous bisphosphonate with proven efficacy in reducing the incidence of skeletal complications and delaying the time to a first skeletal complication. This study was designed to assess the continued benefit of ZOL treatment over a prolonged period.
METHODS: This was a retrospective claims analysis study using information gathered from two national US managed-care plan databases. Patients ≥18 years of age with a single type of solid tumor or MM who were diagnosed with bone lesions and experienced at least one skeletal complication (before or after receiving ZOL) were included.
RESULTS: Of the 28,385 patients, those with lung and breast cancer composed the largest group. Greater percentages of MM and breast cancer patients were treated with ZOL. On average, those with renal cell carcinoma and lung cancer had a longer time between bone metastasis diagnosis and start of therapy with ZOL. Compared with an untreated cohort, patients treated with ZOL had a 24% reduction in incidence of fracture, a 45% reduction in incidence of spinal cord compression, and a 56% reduction in risk of mortality. Patients with persistence with ZOL over 180 days had a reduced incidence of fracture before controlling for other factors.
CONCLUSIONS: Patients treated with ZOL had reduced risks of fracture, spinal cord compression, and mortality compared with patients in the no-treatment cohort. Longer persistence with ZOL was associated with better outcomes. Greatest benefits were observed for patients treated on a regular basis with ZOL for a period beyond 18 months.