Background: Studies show markers of bone turnover can help the clinician in the diagnosis and follow-up of bone metastases. The present study aimed to investigate the value of biochemical markers of bone turnover in the diagnosis and prognosis of bone metastases of malignant tumors.
Material/Methods: The serum levels of C-Telopeptide-Cross-Linked Type I Collagen (CTx), Procollagen Type I N-Terminal Propeptide (PINP), Bone-Specific Alkaline Phosphatase (B-ALP) and Osteocalcin (OST) in patients with bone metastases and control subjects were measured using radioimmunoassay and immunochemiluminescent assay.
Results: The levels of CTx, PINP, B-ALP and OST in the metastasis group were significantly higher than those in both control groups and correlated with the number of bone metastatic sites. The levels of these markers were higher in prostate cancer patients with bone metastasis. The CTX of >426 ng/ml had the highest sensitivity and NPV, and PINP of >51.21 ng/ml had the highest specificity and PPV in healthy subjects. In addition, CTX of >547 ng/ml had the highest sensitivity and OST of >20.34 ng/ml the highest specificity in the non-metastasis group. Furthermore, both B-ALP of >15.55 ng/ml had relatively high negative predictive value and positive predictive value.
Conclusions: Biochemical markers of bone turnover, including CTx, PINP, B-ALP and OST, play important roles in the diagnosis and prognosis of metastatic bone cancer. CTX had a high sensitivity, and PINP had a high specificity in predicting bone metastasis. B-ALP is an ideal biochemical marker of bone turnover for metastatic bone cancer.

Keywords: Peptide Fragments - diagnostic use, Osteocalcin - diagnostic use, Neoplasms - pathology, Luminescent Measurements, Collagen Type I - diagnostic use, Bone Neoplasms - secondary, Analysis of Variance, Alkaline Phosphatase - diagnostic use, Peptides - diagnostic use, Procollagen - diagnostic use, Radioimmunoassay, Tumor Markers, Biological - blood