title: Serum tartrate-resistant acid phosphatase 5b activity as a prognostic marker of survival in breast cancer with bone metastasis.
abstract: BACKGROUND
  Serum tartrate-resistant acid phosphatase 5b (TRACP 5b) activity is a marker of osteoclast number and is elevated in breast cancer (BC) patients with extensive bone metastasis, which might in turn reflect the tumour burden. We tested the hypothesis that baseline serum TRACP 5b activity and its interval change are potential prognostic markers of survival in BC patients with bone metastasis.
  
  
  METHODS
  We analyzed the data from previous prospective studies. A total of 100 patients with newly diagnosed bone metastasis were included. Cox proportional regression model was used to evaluate the correlation between the overall survival time (OS) and baseline serum TRACP 5b activity and its interval changes. The least significant change (LSC) of TRACP 5b was calculated from data obtained from 15 patients with early BC.
  
  
  RESULTS
  Estrogen receptor status (Hazard Ratio (HR) = 0.397; p = 0.003) and visceral metastasis (HR = 0.492; p = 0.0045) were significantly correlated with OS. The OS was significantly shorter in those patients with higher baseline TRACP 5b activity based on a cut-off value to delineate the highest tertile (HR = 3.524; p < 0.0001). Further analysis demonstrated that among patients in the highest tertile, OS was significantly longer in those patients who had achieved a decrease of serum TRACP 5b activity greater than the LSC (38.59%) (p = 0.0015).
  
  
  CONCLUSIONS
  We found that TRACP 5b activity and its interval change after treatment bore a prognostic role in BC patients with bone metastasis and a high baseline serum TRACP 5b activity. Further prospective phase II study is necessary to confirm these results.
authors.affiliation: Breast Cancer Research Group, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Yi-Ying
authors.initials: YY
authors.lastname: Wu
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Janckila
authors.forename: Chih-Hung
authors.initials: CH
authors.lastname: Ku
authors.forename: Cheng-Ping
authors.initials: CP
authors.lastname: Yu
authors.forename: Jyh-Cherng
authors.initials: JC
authors.lastname: Yu
authors.forename: Su-Hui
authors.initials: SH
authors.lastname: Lee
authors.forename: Hsin-Yi
authors.initials: HY
authors.lastname: Liu
authors.forename: Lung T
authors.initials: LT
authors.lastname: Yam
authors.forename: Tsu-Yi
authors.initials: TY
authors.lastname: Chao
mesh_terms: D000135:Acid Phosphatase / Q000378:metabolism*; D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism*; D001859:Bone Neoplasms / Q000201:enzymology* / Q000401:mortality* / Q000473:pathology; D001943:Breast Neoplasms / Q000201:enzymology* / Q000401:mortality* / Q000473:pathology; D016009:Chi-Square Distribution; D005260:Female; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism*; D008875:Middle Aged; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D016019:Survival Analysis; D000071681:Tartrate-Resistant Acid Phosphatase; D013997:Time Factors; D016896:Treatment Outcome; D015854:Up-Regulation
chemical_list: D014408:Biomarkers, Tumor; D007527:Isoenzymes; C000605510:ACP5 protein, human; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase