[Action of bisphosphonates on malignant osteolysis]

MECHANISM OF BONE DESTRUCTION IN MALIGNANT OSTEOLYSIS: Many mechanisms have been described to explain the excessive osteoclastic activity: local stimulation factors (cytokines, lymphokines) are mainly found in breast cancer of myeloma; a general stimulation factor (PTH rP) is found predominantly in lung cancer, head and neck cancer and in cancer of the kidney or ovary. CONTRIBUTION OF BISPHOSPHONATES: The use of bisphosphonates is warranted to counteract the overactivity of the osteoclasts in humans, especially since these drugs could have a direct effect on cancer cells and also have their own therapeutic effect. There are four objectives for using bisphosphonates in cancer patients: lowering serum calcium levels, pain relief, treatment and prevention of bone metastasis. Four bisphosphonates have marketing approval in France for this indication. PROVEN AND TO BE PROVEN EFFECTS: The serum calcium lowering effect and the curative effect for the treatment of bone metastasis are well documented for all four formulations which all meet the clinical requirements for marketing approval. The preventive effect on the development of secondary bone localizations of primary cancers remains to be demonstrated and will require extensive testing in humans. There is however room for hope of substantial progress in cancerology.