Serum C-telopeptide levels predict the incidence of skeletal-related events in cancer patients with secondary bone metastases

We evaluated serum C-telopeptides (CTX) to see whether they may be useful as predictive markers for disease progression in cancer patients with bone metastases who are being treated with zoledronic acid (ZA). This was a prospective, nonrandomised study in which 26 patients with solid tumours and confirmed bone metastases were treated with ZA (4 mg every 3-4 weeks) for 24 months or until a skeletal-related event (SRE) was observed. Serum CTX levels were determined at baseline and 6, 12, 18 and 24 months after study initiation. SRE were evaluated using bone scintigraphy. Study participants had prostate (50%), breast (31%), lung (11%) or bladder (8%) tumours. Mean age was 69 (range 52-84) years, and 65% men. At baseline, overall mean CTX levels were 562.47 +/- 305.17 pg/dl. Patients who showed disease progression during the study period showed significantly higher CTX levels at baseline and after 18 months of ZA treatment than patients who did not progress (p = 0.040 and p = 0.006, respectively). Patients with a parts per thousand yen5 bone metastases at diagnosis had significantly higher CTX levels after 18 months of ZA treatment than patients with < 5 bone metastasis (p = 0.001). Similarly, at 12 and 18 months, patients without SRE had significantly lower CTX levels than patients in whom a SRE was observed (p = 0.005 and p = 0.001, respectively). Changes in serum CTX levels seem to predict the potential for tumour control and the likelihood of developing an SRE in a sample of patients with solid tumours and bone metastases treated with ZA.