A comparison of bone-related biomarkers and CA27.29 to assess response to treatment of osseous metastatic breast cancer

Background: The assessment of bone metastases by clinical examination or im aging techniques is still considered unreliable. We compared a specific mar ker of bone resorption, urinary deoxypyridinoline (DPD)-crosslinks, with se rum calcium (Ca), alkaline phosphatase (AP) and CA27.29, to evaluate the st atus of bone metastases in patients with breast cancer. Materials and Metho ds: Second morning voided urine was collected from 2 groups of patient (pts ), those without evidence of disease (n=118), and those with bone metastase s (n=85) under specific therapy plus pamidronate. DPD and CA27.29 were meas ured on the automated ACS180(R) system (Bayer Diagnostics(R) Tarrytown, NY; USA). Receiver operating characteristics (ROC) curves were established for each of the 4 biomarkers to determine whether they could distinguish the 2 subsets of pts with clinically sufficient validity, and to establish the c orresponding cut-off values. Results: Neither Ca nor AP was useful in discr iminating the 2 subgroups. At a DPD cut-off of 13 nmol/mmol, we found a spe cificity of 69% and a sensitivity of 53% for diagnosing bone metastases. Be st results, however, were seen for CA27.29. A cut-off value of 30 U/ml resu lted in a specificity of 62% and a sensitivity of 81%. Conclusions: CA27.29 was the best parameter for the discrimination of stage IV breast cancer wi th bone metastases. The primary advantage of DPD lies in the monitoring of bone metastases under specific therapy.