The use of molecular markers of bone turnover in the management of patients with metastatic bone disease.

Biochemical markers of bone turnover are widely used in clinical practice. These indices have been shown to be associated with the occurrence, prognosis and therapeutic response of malignant bone lesions. For example, markers of bone resorption are often elevated in patients with established bone metastases and while this may point to a role of these markers in the diagnostic workup of cancer patients, the available evidence does not permit any final conclusions as to the accuracy and validity of the presently used markers in the early diagnosis of bone metastases. Many bone turnover markers appear to respond to antiresorptive and antineoplastic therapies, and recent evidence from prospective trials suggests that the aim of bisphosphonate therapy should be to normalize rates of bone remodelling to optimize therapeutic and prognostic outcomes. However, it remains unknown whether the use of bone markers in the routine clinical setting has any defined beneficial effects on overall outcome in cancer patients. Clearly, bone turnover markers have insufficient diagnostic or prognostic value to be used in isolation; however, the combination of these markers with other diagnostic techniques may improve clinical assessment of patients with bone-seeking cancers. This article reviews the available evidence (as of August 2007) on the clinical use of bone turnover markers in the management of patients with metastatic bone disease.