Bone formation and resorption markers as diagnostic tools for bone metastases evaluation

Bone metastases are a frequent complication of several types of cancers. Since bone metastases are difficult to diagnose with the current available approaches, there is a demand for new methods for assessing bone response. In this context, biochemical markers of bone remodeling may provide useful information on bone turnover that, in turn, may reflect disease activity in bone. In this study we tested a panel of bone remodeling markers (distinguishing between bone formation and bone resorption ones) in different groups of cancer patients, so as to evaluate the potential clinical role of the examined bone remodeling markers in the early diagnosis of metastases formation and progression. Among the bone resorption markers, tartrate resistant acid phosphatase 5b (TRAP5b) resulted the most specific for the metastatic tumor stage. Both the bone formation markers we analyzed displayed a direct correlation (positive for bone-specific alkaline phosphatase [BAP] and negative for osteocalcin [OC]) with tumor disease progression, ranging from healthy controls to primary tumor and, ultimately, to the metastatic stage. Taken together our results suggest that these markers can be valuable tools to be used, in parallel with traditional methods of metastases diagnosis, in order to monitor more in detail the pathological effect of metastases progression in bone tissue.