Treatment of skeletal disease in breast cancer with clodronate

Complications of breast cancer involving the skeleton include hypercalcaemia, bone pain and fracture. These complications arise because of progressive osteolysis which is in turn dependent on the activation of osteoclasts by tumour and host tissues. Clodronate is a powerful inhibitor of osteoclastic bone resorption which led us to evaluate its potential in metastatic breast cancer. When given intravenously it lowers serum calcium in the majority of hypercalcaemic patients. A convenient regimen is 600 mg iv as a single dose infused over several hours. We have additionally shown in a double-blind cross-over study that this regimen also has a significant effect on bone pain. This had led us to assess the longer term effects of clodronate by mouth in a prospective double-blind study of patients with established skeletal metastases. These studies are not yet complete but the agent appears to prevent hypercalcaemia and trends are emerging which indicate that the incidence of bone pain and fractures may also decrease.