Application of N-terminal telopeptide of type I collagen in the evaluation of bone metastasis degree and efficacy.

e23505 Background: Bone metastases is a common complication in advanced malignancies, and the assessment of their severity and treatment response currently relies on imaging modalities such asCT, MRI,PET-CT. However, the widespread application of these imaging techniques is limited by economic constraints, radiation exposure, and other factors. Therefore, it is crucial to explore more economical, real-time assessment methods. This study aimed to investigate the value of urinary N-terminal telopeptide of type I collagen (uNTX) in assessing the severity and treatment response of bone metastases, with the goal of supplementing the limitations of traditional imaging methods. Methods: We assessed the impact of renal function on uNTX excretion rates and used urinary creatinine (uCr) to correct uNTX results (uNTX/uCr) to improve the accuracy of the results. We compared uNTX excretion rates across different bone metastatic burdens and types to analyze the correlation between uNTX and the severity of bone metastases. We analyzed the correlation between uNTX and the maximum standardized uptake value (SUVmax) of bone metastatic lesions on PET-CT in patients with newly diagnosed bone metastases at baseline (n=31) to evaluate the potential of uNTX as a marker of bone metabolism and tumor activity. From baseline, patients received subcutaneous injections of denosumab 120mg monthly and were followed up for 6 months. We compared the changes in uNTX excretion rates before and after follow-up with the results of imaging-based treatment response assessments (using MDA and PERCIST criteria) and generated ROC curves to evaluate the diagnostic performance of uNTX in treatment response assessment. Results: The excretion rate of uNTX decreases in patients with impaired renal function. After uCr correction, the difference was not statistically significant. uNTX excretion rates were positively correlated with bone metastatic burden, and patients with osteolytic metastases had higher uNTX levels. uNTX excretion rates were positively correlated with SUVmax values of bone metastatic lesions (r=0.372). Changes in uNTX excretion rates before and after follow-up were correlated with imaging-based treatment response assessments. ROC curve analysis demonstrated that uNTX can effectively evaluate the treatment response of bone metastases, and its diagnostic performance was superior to that of alkaline phosphatase (ALP). Conclusions: uCr-corrected uNTX excretion rates can effectively reflect the severity and treatment response of bone metastases and have the potential to serve as a convenient auxiliary tool for the clinical management of patients with bone metastases. Combining uNTX measurements with traditional imaging examinations can further improve the assessment system for bone metastasis status and treatment efficacy.