Bone disease from monoclonal gammopathy of undetermined significance to multiple myeloma: pathogenesis, interventions, and future opportunities.

Manifestations of bone disease-osteopenia, osteolytic lesions, and fractures-are the hallmark of multiple myeloma (MM) and occur clinically in the vast majority of patients. These abnormalities can have devastating clinical effects by increasing both the morbidity and mortality of patients. Bone disease is usually found when patients are diagnosed with active MM; however, recent data suggest that it is present in early myelomagenesis, including patients with myeloma precursor disease, monoclonal gammopathy of undetermined significance (MGUS). The primary mechanisms of abnormal bone remodeling are increased osteoclastic activity, which occurs in close proximity to active myeloma cells, and decreased activity of the surrounding osteoblasts. Better understanding of the pathogenesis of bone disease in MM will allow us to enhance our current therapeutic options in the treatment of bone disease. In patients with active MM and at least one lytic lesion, intravenous bisphosphonates have been shown to decrease skeletal-related events and pain, improve performance status, and maintain quality of life. Emerging evidence suggests that intervention at earlier stages of disease may prevent skeletal-related events at time of progression, but there is no evidence that bisphosphonates in this setting change the natural history of the disease.