Biochemical Markers of Bone Turnover in Breast Cancer Patients with Bone Metastases: A Preliminary Report

Background: Some biochemical markers of bone turnover are expected to reflect the disease activity of metastatic bonetumor. In the present study six biochemical markers were evaluated to determine appropriate markers forthedetection of metastatic bone tumors frombreast cancer (BC). Methods: A panel of bone turnover markers was assessed in 11 normocalcemic patients with bone metastases from BC and in 19 BC patients withoutclinical evidence of bone metastases. Bone formation was investigated by measuring serum bone isoenzyme of alkaline phosphatase (BALP), osteocalcin (OC) and carboxy-terminal propeptide of type I procollagen (PICP): Bone resorption was investigated by measuring-serum carboxy-terminal telopeptide of type I collagen (ICTP), fasting urinary pyridinoline (Pyr) and deoxypyridinoline (D-Pyr). Results: PICP was influenced by age and menopausal status. Significant correlations were observed between each of bone turnover markers except between BALP and OC. The mean levelsof the six boneturnovermarkers werehigherinpatients withbonemetastases than in those without them and significance was observed except for OC. The best diagnostic efficiency by receiver-operating characteristic (ROC) analysis was provided by ICTPfollowed by Pyr or D-Pyr, BALP, PICP and OC and significance was observed between ICTP and OC. Multiple logistic regression analysis adjusted by age revealed that the only significant marker related to bone metastases was ICTP. Conclusions: Serum ICTP appears to be the leading marker of bone metastases from BC. However, to reveal the clinical usefulness of these markers, further examination will be needed to accountfor the ease and cost-effectiveness of the measurements.