title: Tartrate-resistant acid phosphatase 5b is a useful serum marker for extensive bone metastasis in breast cancer patients.
abstract: OBJECTIVE
  Previous studies showed that serum tartrate-resistant acid phosphatase 5b (TRACP5b) activity was increased in 70% to 94% of breast cancer (BC) patients with bone metastasis (BM). This study aims to determine whether serum TRACP5b is useful for identifying limited or extensive BM in BC patients.
  
  
  METHODS
  Serum TRACP5b activity was measured in 168 BC patients, including 81 who were newly diagnosed with early BC, 20 with extraosseous metastasis, 24 with limited BM, and 43 with extensive BM. Serum TRACP5b activity was also measured monthly in 151 patients with early BC until they developed BM. Four hundred and twenty-seven (427) healthy women ages 18 to 90 served as control. One-way ANOVA was used to compare serum TRACP5b among groups. The sensitivity and specificity of serum TRACP5b as a marker for BM were estimated by receiver operator characteristic (ROC) curves.
  
  
  RESULTS
  Serum TRACP5b increased with age in healthy women ( P < 0.0001). It was significantly elevated in patients with extensive BM compared with all other groups ( P < 0.0001). ROC analysis established a cutoff value of 4.026 units/L to identify patients with extensive BM with a specificity of 98% and a sensitivity of 93% (area under the curve = 0.9807; 95% CI = 0.9698-0.9915). Among the 151 patients with early BC, 6 developed limited BM and 2 developed extensive BM during the follow-up period. Serum TRACP5b remained below the cutoff value in patients with limited BM, but became significantly increased in those whose BM became extensive.
  
  
  CONCLUSIONS
  Serum TRACP5b activity is a useful diagnostic marker for extensive BM in patients with BC.
authors.affiliation: Breast Cancer Research Group, Tri-Service General Hospital, National Defense Medical Center, No. 325 Cheng Kung Road, Section 2, Nei-Hu 114, Taipei, Taiwan. j0607@ms6.hinet.net
authors.forename: Tsu-Yi
authors.initials: TY
authors.lastname: Chao
authors.forename: Jyh-Cherng
authors.initials: JC
authors.lastname: Yu
authors.forename: Chih-Hung
authors.initials: CH
authors.lastname: Ku
authors.forename: Mary M
authors.initials: MM
authors.lastname: Chen
authors.forename: Su-Huei
authors.initials: SH
authors.lastname: Lee
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Janckila
authors.forename: Lung T
authors.initials: LT
authors.lastname: Yam
mesh_terms: D000135:Acid Phosphatase / Q000097:blood*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000097:blood*; D001859:Bone Neoplasms / Q000175:diagnosis* / Q000556:secondary*; D001943:Breast Neoplasms / Q000473:pathology*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007527:Isoenzymes / Q000097:blood*; D008875:Middle Aged; D012680:Sensitivity and Specificity; D000071681:Tartrate-Resistant Acid Phosphatase
chemical_list: D014408:Biomarkers, Tumor; D007527:Isoenzymes; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase