Bone metastasis in breast cancer.

Bone metastases in breast cancer are common and frequently lead to serious skeletal related morbid complications. Metastases develop in areas of metabolically active trabecular bone. It is presumed that breast cancer cells undergo the same stepwise process for metastases development as demonstrated in other tumor types. The specific factor or factors responsible for the osteotropism of breast cancer have not been identified. The morbid events associated with skeletal metastases, such as pathologic fracture, and spinal cord compression, may be assessed objectively by a variety of techniques including skeletal radiography, radionuclide scanning, computed tomographic scanning and magnetic resonance imaging. Biochemical parameters or markers of skeletal metastases are not sensitive enough to detect clinically occult disease. Therapeutic interventions for bone metastases include local and systemic therapies. Surgery and radiation therapy are most frequently used for relief of pain or impending fracture, or when bone fracture or neurologic compromise has already developed. Systemic treatment of bone metastases appears to be as effective as systemic treatment of other metastatic sites. Both hormone and chemotherapy may provide significant palliation. Clinical research suggests that the adjunctive use of bisphosphonates may significantly reduce the incidence of skeletal-related morbid events associated with osteolytic bone disease. Future research efforts directed at determining the osteotrophic factors responsible for bone metastases in breast cancer, the pathophysiology of the bone remodeling process in metastatic disease and the prophylactic use of bisphosphonates may lead to significant clinical benefit for those in whom bone metastases from breast cancer develop.