title: Retrospective analysis of antitumor effects of zoledronic acid in breast cancer patients with bone-only metastases.
abstract: BACKGROUND
  Bisphosphonates have been used successfully in the treatment of hypercalcemia and to reduce skeletal complications of bone metastasis, but have not been shown to prevent bone metastasis or to prolong survival time in metastatic breast cancer patients. The aim of this study was to determine whether the progression-free survival (PFS) and overall survival (OS) of patients with bone-only breast cancer metastasis differed based on whether patients received zoledronic acid, pamidronate, or no bisphosphonate upon diagnosis of their metastases.
  
  
  METHODS
  We retrospectively identified 314 patients diagnosed with bone-only metastasis at the time of initial staging or who developed bone metastasis as the first recurrence site during follow-up from January 1, 1997 to December 31, 2008, at The MD Anderson Cancer Center. Univariate and multivariate Cox hazards models were used to assess the effects of each treatment on PFS and OS.
  
  
  RESULTS
  Patients who had more than 1 bone metastasis and Eastern Cooperative Oncology Group (ECOG) performance status of 2 and 3 were more likely to receive zoledronic acid in this analysis. Compared with no bisphosphonate use, the use of zoledronic acid was not significantly associated with longer PFS (hazard ratio [HR] = 0.72, P = .058 in univariate analysis, and HR = 0.80, P = .235 in multivariate analysis) nor with longer OS (HR = 1.04, P = .863 in univariate analysis and HR = 1.34, P = .192 in multivariate analysis).
  
  
  CONCLUSIONS
  Our study demonstrates that for patients with bone-only metastases, zoledronic acid did not prolong PFS or OS. In patients with bone-only metastasis, we could not demonstrate antitumor effects of zoledronic acid.
authors.affiliation: Department of Breast Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
authors.forename: Naoki
authors.initials: N
authors.lastname: Niikura
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.forename: Naoki
authors.initials: N
authors.lastname: Hayashi
authors.forename: Shana L
authors.initials: SL
authors.lastname: Palla
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Tokuda
authors.forename: Gabriel N
authors.initials: GN
authors.lastname: Hortobagyi
authors.forename: Naoto T
authors.initials: NT
authors.lastname: Ueno
authors.forename: Richard L
authors.initials: RL
authors.lastname: Theriault
mesh_terms: D000328:Adult; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D050071:Bone Density Conservation Agents / Q000627:therapeutic use*; D001859:Bone Neoplasms / Q000188:drug therapy* / Q000401:mortality / Q000556:secondary*; D001943:Breast Neoplasms / Q000401:mortality / Q000473:pathology*; D004164:Diphosphonates / Q000627:therapeutic use*; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D007093:Imidazoles / Q000627:therapeutic use*; D008875:Middle Aged; D000077268:Pamidronate; D012189:Retrospective Studies; D000077211:Zoledronic Acid
chemical_list: D000970:Antineoplastic Agents; D050071:Bone Density Conservation Agents; D004164:Diphosphonates; D007093:Imidazoles; D000077211:Zoledronic Acid; D000077268:Pamidronate