title: Comparison of diagnostic and prognostic performance of two assays measuring thymidine kinase 1 activity in serum of breast cancer patients.
abstract: BACKGROUND
  We compared two recently developed immunoassays for serum thymidine kinase 1 (TK1) activity: one manual assay (DiviTum, Biovica(®)) and one fully automated assay (Liaison, Diasorin(®)).
  
  
  METHODS
  The study included 368 women: 149 healthy blood donors (control), 59 patients with benign breast disease (BBD) and 160 patients with primary breast cancer (BC).
  
  
  RESULTS
  A regression analysis of the Liaison (y) and DiviTum (x) assays for all three groups yielded the equation y=3.93+0.03x (r=0.85, n=368). The r-value in BC was higher than in control and BBD (0.90 vs. 0.81 and 0.64). The correlation between the two assays for TK1 values above the cut-off was higher compared to that below (0.88 and 0.59). Breakdown of the BBD group into subgroups with proliferative and non-proliferative lesions was effective only with the measurement of TK1 with DiviTum assay (p=0.03). The TK1 activity determined preoperatively in BC patients with DiviTum and Liaison assays was significantly associated with T-stage (for both p=0.01), presence of vascular invasion (p=0.002 and p=0.02), lack of estrogen receptor (ER) (p=0.001 and p=0.01) and progesterone receptor (PR) (p=0.01 and p=0.03) expression. Only TK1 analyzed with the DiviTum assay was associated with tumor grade and molecular subtype of BC (p=0.02 and p=0.003). Multivariate Cox proportional hazards analyses demonstrated that T-stage, PR status and TK1 activity measured by both methods (DiviTum, RR=3.0, p=0.02 and Liaison, RR=3.1, p=0.01) were independent predictors of disease recurrence.
  
  
  CONCLUSIONS
  In spite of differences observed between TK1 activity measured by the DiviTum and Liaison assays, both of them may be used for recurrence prediction in preoperative evaluation of BC patients.
authors.affiliation: Department of Oncology, Hadassah and Hebrew University Medical Centre, P.O. Box 12000, Jerusalem 91120, Israel. nisman@hadassah.org.il
authors.forename: Benjamin
authors.initials: B
authors.lastname: Nisman
authors.forename: Tanir
authors.initials: T
authors.lastname: Allweis
authors.forename: Luna
authors.initials: L
authors.lastname: Kadouri
authors.forename: Bela
authors.initials: B
authors.lastname: Mali
authors.forename: Tamar
authors.initials: T
authors.lastname: Hamburger
authors.forename: Mario
authors.initials: M
authors.lastname: Baras
authors.forename: Simon
authors.initials: S
authors.lastname: Gronowitz
authors.forename: Tamar
authors.initials: T
authors.lastname: Peretz
mesh_terms: D000367:Age Factors; D000368:Aged; D001331:Automation; D014408:Biomarkers, Tumor / Q000097:blood*; D001943:Breast Neoplasms / Q000201:enzymology* / Q000473:pathology / Q000601:surgery; D048708:Cell Growth Processes / Q000502:physiology; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000379:methods; D008875:Middle Aged; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D011379:Prognosis; D013937:Thymidine Kinase / Q000097:blood*
chemical_list: D014408:Biomarkers, Tumor; D013937:Thymidine Kinase; C092717:thymidine kinase 1