title: Serum Dickkopf-1 acts as a new biomarker in human breast cancer.
abstract: BACKGROUND
  The serum levels of Dickkopf-1 (DKK1), a secreted Wnt family protein, are different in patients suffering various types of cancers. In the present study, we aim to explore the diagnostic value of DKK1 as a new biomarker in breast cancer.
  
  
  METHODS
  Serum was collected from 38 patients with breast cancer and 23 healthy controls. Serological levels of DKK1 were examined by enzyme-linked immunosorbent assay (ELISA). Significance and diagnostic performance including receiver operator characteristic (ROC) and areas under the curve were determined by SPSS software.
  
  
  RESULTS
  Serum level of DKK1 was significantly increased in breast cancer patients compared to the healthy controls (P˂0.05). The expression levels of CA15-3 were also evaluated in patients suffering from breast cancer in comparison with healthy controls (P˂0.05). AUC for DKK1 and CA15-3 were 0.81 and 0.64 respectively. Sensitivity and specificity of DKK1 were more than CA15-3 in earlier stage of breast cancer. DKK1 expression in HER-2, estrogen receptor (ER) and progesterone receptor (PR) positive patients was decreased compared with HER-2, ER and PR negative patients.
  
  
  CONCLUSIONS
  We found that the expression level of DKK1 in serum was increased in breast cancer patients, suggesting that serum expression level of DKK1 could be a useful biomarker in breast cancer.
authors.affiliation: Department of Breast Surgery, Dalian Central Hospital, Dalian, China - jintaohailang009@163.com.
authors.forename: Jin-Tao
authors.initials: JT
authors.lastname: Liu
authors.affiliation: Department of Breast Surgery, Dalian Central Hospital, Dalian, China.
authors.forename: Wen-Bin
authors.initials: WB
authors.lastname: Guo
authors.affiliation: Department of Breast Surgery, Dalian Central Hospital, Dalian, China.
authors.forename: Jia-Yi
authors.initials: JY
authors.lastname: Sun
mesh_terms: D014408:Biomarkers, Tumor / Q000097:blood*; D001943:Breast Neoplasms / Q000097:blood / Q000175:diagnosis* / Q000235:genetics*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000097:blood*; D008875:Middle Aged; D009367:Neoplasm Staging; D011237:Predictive Value of Tests; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000097:blood; D012680:Sensitivity and Specificity
chemical_list: D014408:Biomarkers, Tumor; D036341:Intercellular Signaling Peptides and Proteins; D018719:Erb-b2 Receptor Tyrosine Kinases; C501126:DKK1 protein, human; C508053:ERBB2 protein, human