title: Quantitative evaluation of protein expression as a function of tissue microarray core diameter: is a large (1.5 mm) core better than a small (0.6 mm) core?
abstract: BACKGROUND
  Tissue microarrays (TMAs) have emerged as a high-throughput technology for protein evaluation in large cohorts. This technique allows maximization of tissue resources by analysis of sections from 0.6-mm to 1.5-mm core "biopsies" of standard formalin-fixed, paraffin-embedded tissue blocks and by the processing of hundreds of cases arrayed on a single recipient block in an identical manner.
  
  
  OBJECTIVE
  To assess the expression of a series of biomarkers as a function of core size. Although pathologists frequently feel better if larger core sizes are used, there is no evidence in the literature showing that large cores are better (or worse) than small cores for assessment of TMAs.
  
  
  METHODS
  Estrogen receptor, HER2/neu, epidermal growth factor receptor, STAT3, mTOR, and phospho-p70 S6 kinase were measured by immunofluorescence with automated quantitative analysis. One random 0.6-mm field (one 0.6-mm spot) was compared to 6 to 12 fields per spot, representing 1-mm and 1.5-mm cores, for 3 different tumor types.
  
  
  RESULTS
  We show that measurement of a single random 0.6-mm spot was comparable to analysis of the whole 1-mm or 1.5-mm spot (Pearson R coefficient varying from 0.87-0.98) for all markers tested.
  
  
  CONCLUSIONS
  Since TMA technology is now being used in all phases of biomarker development, this work shows that TMAs with 0.6-mm cores are as representative as those with any common larger core size for optimization of standardized experimental conditions. Given that a greater number of 0.6-cores can be arrayed in a single master block, use of this core size allows increased throughput and decreased cost.
authors.affiliation: Department of Pathology, Yale University School of Medicine, New Haven, Connecticut 06520-8023, USA.
authors.forename: Valsamo K
authors.initials: VK
authors.lastname: Anagnostou
authors.forename: Frank J
authors.initials: FJ
authors.lastname: Lowery
authors.forename: Konstantinos N
authors.initials: KN
authors.lastname: Syrigos
authors.forename: Philip T
authors.initials: PT
authors.lastname: Cagle
authors.forename: David L
authors.initials: DL
authors.lastname: Rimm
mesh_terms: D000465:Algorithms; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology; D002289:Carcinoma, Non-Small-Cell Lung / Q000378:metabolism / Q000473:pathology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008175:Lung Neoplasms / Q000378:metabolism / Q000473:pathology; D008297:Male; D009363:Neoplasm Proteins / Q000378:metabolism*; D009369:Neoplasms / Q000378:metabolism* / Q000473:pathology; D040081:Protein Array Analysis / Q000379:methods* / Q000706:statistics & numerical data; D046888:Tissue Array Analysis / Q000379:methods* / Q000706:statistics & numerical data
chemical_list: D009363:Neoplasm Proteins