Clinical Significance Of Urinary NTX For Metastatic Tumors Of Bone

Objectives: Urinary cross-linked N-telopeptides of typeⅠcollagen(uNTX) increase in concentration when bone resorption is increased ,such as osteoporosis and bone metastasis. The aim of this study was to evaluate the urine levels of NTX in a sample of patients with several types of solid tumors to discuss its relationship with diagnosis and development of metastatic tumors of bone.Methods: Serum and urine were taken from 89 tumor patients aged 30~82 years old. Urine levels of NTX were determined by enzyme-linked immunosorbent assay and serum levels of ALP and Ca were determined by colorimetric methods. Based on the results of imaging techniques(including bone scintigraphy, computed tomography(CT),magnetic resonance imaging(MRI) and X-ray), all patients were divided into 2 groups. Group A was composed of 42 primary tumor patients with bone metastases. Group B was composed of 47 primary tumor patients without bone metastases. At the same time , 55 healthy adult people were as Group C. During the study, 15 patients with bone metastases received zoledronate 4mg intravenously monthly for up to 3 months. Urine levels of NTX were measured again after treatment.Results:①There were no significant differences in age, gender and tumor type of the patients with and without bone metastases.②patients with bone metastases had significantly higher mean values of uNTX and sALP than those without bone metastases and normal(P﹤0.01), and uNTX values were also higher in patients without metastases than normal(P﹤0.05). while sCa did not show significant differences.③U sing a cut-off value of 65 nmol BCE/mmol Cr for uNTX,sensitivity and specificity were 62% and 83%, while using a cut-off value of 120U/L for sALP, the responding percentages were 57% and 66%.④Among the groups without bone metastases, with low bone lesions and with multiple bone lesions, uNTX all showed significant increases(P﹤0.05), while sALP showed significant increases only in those with multiple bone lesions(P﹤0.05).⑤T he bone metastatic patients with SREs had significantly higher urine levels of NTX(P﹤0.05).⑥After zoledronate therapy, the average reduction percent of uNTX in the effective patients was 43.5%, but the average value of uNTX in the refractory patients did not show any significant changes .Conclusions: The mean levels of uNTX in Group A were much higher than those in Group B and in Group C. The measurement of bone resorption marker uNTX was useful for tumor patients prone to bone metastases. uNTX was a specific marker correlated with bone resorption state. The levels of uNTX increased when patients were with bone metastases and were correlated with the extent of bone metastases. The diagnostic validity of uNTX was higher than sALP and sCa. Its change was prior to X-ray. Therefore, uNTX could be used broadly in prediction, diagnosis and the evaluation of treatment of metastatic tumors of bone.