Clinical Significance of the Serum Crosslinked N-Telopeptide of Type I Collagen as a Prognostic Marker for Non–Small-Cell Lung Cancer

IntroductionLung cancer is the leading cause of cancer-related death. Many patients with lung cancer are in its advanced stages at the time of diagnosis. The 5-year survival rate for lung cancer is 10% to 20%, and the prognosis for patients with lung cancer is still poor. The crosslinked N-terminal telopeptide of type I collagen (NTx) is a metabolite of type I collagen, the main constituent of bone matrix.Patients and MethodsWe measured serum NTx levels in patients who underwent staging during hospitalization for the initial treatment of lung cancer in our department. We examined whether serum NTx levels would be relevant to the prognosis of non–small-cell lung cancer (NSCLC).ResultsThis study included 176 patients with lung cancer (125 men and 51 women), including 109 with adenocarcinoma, 53 with squamous cell carcinoma, 6 with large-cell carcinoma, and 8 with other cancer types. Univariate and multivariate analysis using the Cox proportional hazards model revealed a particularly close association between sex, performance status, disease stage, and serum NTx levels and overall survival (OS). A median OS of 368 days was observed for patients with a serum NTx level < 22 nmol BCE/L, which was significantly longer than the 197 days for patients with a serum NTx level ≥ 22 nmol BCE/L (hazard ratio [HR], 2.02; 95% confidence interval [CI], 1.36-2.99; log-rank P = .00037).ConclusionsWe have revealed that a high serum NTx level (> 22 nmol BCE/L) appears to be a risk factor for a reduction in OS in patients with NSCLC.