9013 Background: In patients (pts) with bone metastases, elevated N-telopeptide of type I collagen (NTX) levels correlate with increased relative risks (RR) of skeletal-related events (SREs), disease progression, and death (Brown et al. J Natl Cancer Inst. 2005;97:59–69; Coleman et al. J Clin Oncol. 2005;23:4925–4935). Therefore, we conducted an exploratory analysis of 3 large, randomized, controlled trials to investigate whether reductions in NTX levels by treatment with zoledronic acid (ZOL) correspond with decreased risks of SREs and death. Methods: Urinary NTX was measured at baseline and at 3 months in pts with bone metastases from breast (BC; n = 379), prostate (PC; n = 314), or lung cancer and other solid tumors (LC/OST; n = 204) who received ZOL for up to 24 months. Pts were stratified by baseline NTX levels (normal, < 64 nmol/mmol creatinine; elevated, = 64 nmol/mmol creatinine). Results: Approximately 50% of pts had elevated baseline NTX, and NTX normalization occurred within 3 months of ZOL tre...