The Role of Bisphosphonates in the Treatment of Skeletal Complications of Breast Cancer

Abstract

Bone metastasis from breast cancer can result in significant morbidity including hypercalcemia, fractures, spinal cord compression, and pain. Treatment modalities have included radiation therapy, surgery, analgesia, and bisphosphonates. Clodronic acid, pamidronic acid, ibandronic acid, and zoledronic acid are the four bisphosphonates that have been investigated in metastatic breast cancer. Pamidronic acid, clodronic acid, and ibandronic acid, evaluated in this setting in randomized, double-blind, placebo-controlled trials, have all demonstrated significant improvements in delaying and treating skeletal events in breast cancer patients, including symptom improvement. Pamidronic acid and zoledronic acid appear to be equal with respect to efficacy and safety. Based on several large randomized studies, pamidronate 90mg infused over 2 hours, or zoledronic acid 4mg over 15 minutes every 3–4 weeks is recommended in patients with breast cancer and radiographic evidence of bone destruction. The major toxicity associated with either bisphosphonate is renal impairment and, therefore, monitoring of serum creatinine levels prior to each administration of either agent is recommended. The adverse effects of this class of agents also include gastrointestinal symptoms.