Urinary N-telopeptide (uNTx) is an independent prognostic factor for overall survival in patients with bone metastases from castration-resistant prostate cancer

Background: In patients with bone metastases from castration-resistant prostate cancer (CRPC) not pretreated with a bisphosphonate elevated N-telopeptide of type I collagen (uNTx), a marker of bone resorption, predicts skeletal-related events (SRE). The aim of this study was to assess the prognostic value of uNTx for overall survival (OS) and the incidence of SRE in patients with bone metastases from CRPC receiving zoledronic acid. Methods: From 2004 to 2007, 94 patients with bone metastases from CRPC receiving zoledronic acid for at least 2 months were screened for uNTx. Results: Median age was 66 years (range 46-88). Median serum prostate-specific antigen (PSA) was 66 ng/ml (0-3984) and median uNTx was 19 nmol/mM creatinine (3-489). During follow-up, 38 patients (40%) experienced an SRE. Median OS was 20 months [95% (CI) confidence interval 15-24). In the multivariate analysis, elevated uNTx [hazard ratio (HR) 2.2 (95% CI 1.2-4.0)], serum PSA [HR 2.8 (95% CI 1.6-5.1)], and ECOG performance status were the only independent prognostic factors for OS. Median OS was 12 months (10-16) and 25 months (21-34) in patients with uNTx <0 nmol/mM creatinine and in those with uNTx <20 nmol/mM creatinine, respectively. Conclusion: An elevated uNTx level is an independent prognostic factor for OS in patients with bone metastases from CRPC receiving a bisphosphonate.