Metastatic Bone Disease in Patients with Solid Tumors—Burden of Bone Disease and the Role of Zoledronic Acid

Bisphosphonates have become an integral component of the therapeutic repertoire for cancer patients at risk for skeletal-related events (SREs) such as pathologic fractures, bone pain requiring palliative radiotherapy, the need for orthopedic surgery, spinal cord compression, and hypercalcemia of malignancy because of bone metastases. Administered via monthly 15-minute infusion of up to 4 mg (depending on creatinine clearance rate), zoledronic acid (ZOL) has been approved for preventing SREs in patients with bone metastases from any solid tumor or bone lesions from multiple myeloma. Although there have been limited head-to-head comparison trials between bisphosphonates, ZOL displayed benefits beyond pamidronate in a large-scale comparative trial in patients with bone metastases from breast cancer. Monitoring of serum creatinine levels and oral health is important to ensure safety and comfort during treatment. In addition to the established benefits of bisphosphonates in the advanced cancer setting, there is a strong preclinical rationale and emerging clinical evidence that ZOL has antitumor activities and can delay metastasis in patients with early breast cancer. Studies are underway in patients with other tumor types, and the role of bisphosphonates is likely to evolve.