title: Elevated levels of thymidine kinase 1 peptide in serum from patients with breast cancer.
abstract: OBJECTIVE
  Thymidine kinase (TK) has an important role in DNA synthesis and is thus related to cell proliferation and turn-over. Traditionally, TK has been measured by enzymatic activity or radioimmunoassays. These assays are difficult to adapt to random access instruments. The aim of this study was to evaluate a new immunological sandwich assay for detection of TK peptides in serum from breast cancer patients.
  
  
  METHODS
  Serum samples were collected from patients with breast cancer and stored frozen at -70 degrees C. The samples were collected after surgery, after metastatic tumor recurrence and after chemotherapy due to tumour recurrence. Patients' serum samples were analysed by the TK enzyme-linked immunosorbent assay (ELISA).
  
  
  RESULTS
  In receiver operating characteristics (ROC) analyses of TK1 for diagnosis of breast cancer, the area under the curve (AUC) collected four weeks after surgery was 0.56 (95% CI 0.47-0.65), for samples collected postsurgically after tumour recurrence 0.73 (95% CI 0.65-0.80), and after chemotherapy 0.64 (95% CI 0.56-0.72).
  
  
  CONCLUSIONS
  This study indicates that the tumour proliferation marker TK has a potential as a serum marker in breast cancer. Further studies are warranted to verify this observation.
authors.affiliation: Department of Medical Sciences, Clinical Chemistry, University Hospital, Uppsala, Sweden. Lena.carlsson@medsci.uu.se
authors.forename: Lena
authors.initials: L
authors.lastname: Carlsson
authors.forename: Anders
authors.initials: A
authors.lastname: Larsson
authors.forename: Henrik
authors.initials: H
authors.lastname: Lindman
mesh_terms: D014408:Biomarkers, Tumor / Q000097:blood*; D001943:Breast Neoplasms / Q000097:blood / Q000201:enzymology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D010446:Peptide Fragments / Q000097:blood*; D012372:ROC Curve; D012680:Sensitivity and Specificity; D013937:Thymidine Kinase / Q000097:blood* / Q000737:chemistry
chemical_list: D014408:Biomarkers, Tumor; D010446:Peptide Fragments; D013937:Thymidine Kinase; C092717:thymidine kinase 1