Breast cancer: Bisphosphonate therapy for metastatic bone disease

The indications of bisphosphonate therapy in breast cancer patients go from the correction of hypercalcemia to the prevention of cancer treatment-induced bone loss. Bisphosphonates are part of our therapeutic armamentarium against metastatic bone pain, and at least 50% of the patients benefit from a clinically relevant analgesic effect. Placebo-controlled trials with oral or i.v. bisphosphonates have shown that prolonged administration can reduce the frequency of skeletal-related events by 30% to 40%. The superiority of zoledronic acid compared with pamidronate has been shown by a multiple-event analysis in a large randomized trial. The short infusion time of zoledronic acid also constitutes a convenient therapy. Where available oral ibandronate offers an interesting alternative especially for patients receiving hormone therapy. There are some toxicity concerns with the prolonged use of bisphosphonates. The occasional renal toxicity of zoledronic acid has led to the recommendation to monitor renal function before each infusion and to adjust the dose according to creatine clearance. Osteonecrosis of the jaw could occur in up to 2.5% of breast cancer patients during long-term bisphosphonate therapy. It is often a significant complication that seems to be linked with the duration of therapy.