title: Serum C-telopeptide levels predict the incidence of skeletal-related events in cancer patients with secondary bone metastases.
abstract: BACKGROUND
  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).
  
  
  METHODS
  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.
  
  
  RESULTS
  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 ≥ 5 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).
  
  
  CONCLUSIONS
  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.
authors: Radiation Oncology Department, Hospital Central de la Defensa Gómez Ulla, Madrid, Spain. clopcar@oc.mde.es
authors: María Concepción
authors: MC
authors: López-Carrizosa
authors: Pilar María
authors: PM
authors: Samper-Ots
authors: Aurora Rodríguez
authors: AR
authors: Pérez
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D014408:Biomarkers, Tumor / Q000097:blood*; D050071:Bone Density Conservation Agents / Q000627:therapeutic use; D001859:Bone Neoplasms / Q000378:metabolism / Q000473:pathology / Q000556:secondary*; D001842:Bone and Bones / Q000473:pathology*; D024042:Collagen Type I / Q000097:blood*; D004164:Diphosphonates / Q000627:therapeutic use; D018450:Disease Progression; D005260:Female; D005598:Fractures, Spontaneous / Q000473:pathology*; D006801:Humans; D007093:Imidazoles / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000473:pathology*; D010455:Peptides / Q000097:blood*; D011379:Prognosis; D011446:Prospective Studies; D018709:Statistics, Nonparametric; D000077211:Zoledronic Acid
chemical_list: D014408:Biomarkers, Tumor; D050071:Bone Density Conservation Agents; D024042:Collagen Type I; D004164:Diphosphonates; D007093:Imidazoles; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; D000077211:Zoledronic Acid