Clinical application of urinary NTx in patients with bone metastases from lung cancer.

OBJECTIVE: To investigate the clinical value of urinary N-telopeptide (NTx) of type I collagen in diagnosing bone metastasis (BM) from lung cancer and to optimize a multi-indicator combined detection strategy.

METHODS: The study enrolled patients from a healthy control group, a lung cancer without bone metastases (LC-nonBM) group, and a lung cancer with bone metastases (LC-BM) group. The diagnostic performance of NTx-to-creatinine ratio (NTx/Cr) was evaluated by comparing biochemical indicators, staging characteristics, and receiver operating characteristic (ROC) curve analysis.

RESULTS: NTx/Cr showed statistically significant differences across various stages within the LC-nonBM group (P = 0.004). In the LC-BM group, NTx/Cr levels were significantly elevated (P < 0.001) and positively correlated with the number of bone metastatic lesions. ROC curve analysis revealed that NTx/Cr alone achieved an areas under the curve (AUC) of 0.78 for diagnosing bone metastasis, while the three-indicator combination of the urinary NTx/Cr, serum alkaline phosphatase (ALP), and calcium (Ca) reached an AUC of 0.882, indicating a marked improvement in diagnostic performance.

CONCLUSION: Urinary NTx/Cr is an effective biomarker for diagnosing bone metastasis in lung cancer, and its level is closely associated with tumor stage and metastatic burden. A multi-indicator diagnostic model combining NTx/Cr, ALP, and Ca significantly enhances diagnostic accuracy.