Mechanisms and treatment for bone metastases

Alterations in bone architecture and mineral metabolism are common complications of malignancy. Cancers such as breast, prostate, and lung can affect the skeleton either indirectly through the elaboration of factors that act to disrupt normal calcium homeostasis at the level of the kidney and bone; or directly via secondary spread of tumor to bone. Although the pathophysiology of these skeletal complications is diverse, it is clear that the osteoclast and osteoblast are not just bystanders but are active participants in the development and progression of hypercalcemia and bone metastasis. Our understanding of the molecular mechanisms of metastasis leading to tumor cell escape, homing, adhesion, and secondary growth in a hospitable environment are evolving. Treatment modalities aimed at not only reducing tumor burden but altering the skeletal response to tumor have shown benefit. Newer generation bisphosphonates are quite effective in controlling hypercalcemia of malignancy and have been shown to delay progression of skeletal metastases. Clearly, cancer-associated bone morbidity remains a major public health problem. To improve therapy and prevention it is important to understand the pathophysiology of the effects of cancer on bone. This review will detail scientific advances regarding this area.