CANCER-INDUCED OSTEOLYSIS AND SYSTEMIC TREATMENT

Bone destruction or osteolysis, is a frequent complication of a variety of solid and hematological malignancies. Such skeletal complications may arise due to local osteolysis following metastatic invasion of bone, or to humorally mediated osteolysis produced through the secretion of systemic factors by the tumour or host cells. The final common pathway for this bone destruction is the increased activity of osteoclasts. Although the plain radiograph and the UICC criteria of response remain the "gold standard" for assessing the efficacy of treatment, it is clear that reliable alternatives are necessary. Monitoring of bone metabolism appears the most promising and the most likely method to replace the plain radiograph. In general, the treatment of bone metastases is aimed at palliating symptoms, with cure, only rarely a realistic aim, dependent on the underlying disease. Systemic therapy for bone metastases may be directed against the tumour cell, in order to reduce proliferation and the production of cytokines and growth factors, or may be directed against blocking the effect of these substances on host cells. Of the avalailable resorption inhibitors biphosphonates are the most active drugs in this area and are currently the subject of numerous trials.