Dosing of zoledronic acid with its anti-tumor effects in breast cancer

Bisphosphonates have played an important role in the treatment of breast cancer, mainly in patients with bone metastasis, by reducing the risk of fracture, spinal cord compression, and hypercalcemia. Zoledronic acid, the most frequently used intravenous agent, has been traditionally administered on a monthly dosing schedule. Preclinical studies have demonstrated that zoledronic acid can inhibit angiogenesis, invasion, and adhesion of tumor cells. Several clinical studies of different timings and schedules of zoledronic acid therapy have demonstrated its anti-tumor effects, as well as its protective effect on bone health, in postmenopausal women during adjuvant breast cancer therapy. In general, early initiation of zoledronic acid, concomitantly with adjuvant therapy, has been found to be most beneficial. However, questions remain over the most effective schedule of treatment and relative potency of zoledronic acid. Therefore, we review the existing clinical studies to examine the influence of dosing of zoledronic acid therapy on clinical outcomes in patients with breast cancer.