The prospective analysis of urinary N-telopeptides, collagen break down products type I (NTX), in patients with metastatic bone disease revealed a positive relation between NTX level and risk of Skeletal related events (SREs). Normalization of NTX level at 3 months decreases the rate of serious types of SREs (pathological fractures and cord compression). Zoledronic acid decreases the rate of one or more SREs by four times in patients with elevated NTX levels compared to no Zoledronic acid.