title: Gene expression profiles help identify the tissue of origin for metastatic brain cancers.
abstract: BACKGROUND
  Metastatic brain cancers are the most common intracranial tumor and occur in about 15% of all cancer patients. In up to 10% of these patients, the primary tumor tissue remains unknown, even after a time consuming and costly workup. The Pathwork Tissue of Origin Test (Pathwork Diagnostics, Redwood City, CA, USA) is a gene expression test to aid in the diagnosis of metastatic, poorly differentiated and undifferentiated tumors. It measures the expression pattern of 1,550 genes in these tumors and compares it to the expression pattern of a panel of 15 known tumor types. The purpose of this study was to evaluate the performance of the Tissue of Origin Test in the diagnosis of primary sites for metastatic brain cancer patients.
  
  
  METHODS
  Fifteen fresh-frozen metastatic brain tumor specimens of known origins met specimen requirements. These specimens were entered into the study and processed using the Tissue of Origin Test. Results were compared to the known primary site and the agreement between the two results was assessed.
  
  
  RESULTS
  Fourteen of the fifteen specimens produced microarray data files that passed all quality metrics. One originated from a tissue type that was off-panel. Among the remaining 13 cases, the Tissue of Origin Test accurately predicted the available diagnosis in 12/13 (92.3%) cases.
  
  
  CONCLUSIONS
  This study demonstrates the accuracy of the Tissue of Origin Test when applied to predict the tissue of origin of metastatic brain tumors. This test could be a very useful tool for pathologists as they classify metastatic brain cancers.
authors.affiliation: Department of Laboratory Medicine, University of California-San Francisco, CA 94143, USA.
authors.forename: Alan H B
authors.initials: AH
authors.lastname: Wu
authors.forename: Julia C
authors.initials: JC
authors.lastname: Drees
authors.forename: Hangpin
authors.initials: H
authors.lastname: Wang
authors.forename: Scott R
authors.initials: SR
authors.lastname: VandenBerg
authors.forename: Anita
authors.initials: A
authors.lastname: Lal
authors.forename: William D
authors.initials: WD
authors.lastname: Henner
authors.forename: Raji
authors.initials: R
authors.lastname: Pillai
mesh_terms: D000328:Adult; D001706:Biopsy; D001932:Brain Neoplasms / Q000235:genetics* / Q000556:secondary; D005260:Female; D020869:Gene Expression Profiling / Q000379:methods; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008297:Male; D008875:Middle Aged; D009382:Neoplasms, Unknown Primary / Q000235:genetics* / Q000473:pathology; D020411:Oligonucleotide Array Sequence Analysis; D011237:Predictive Value of Tests; D011933:Reagent Kits, Diagnostic; D015203:Reproducibility of Results; D055815:Young Adult
chemical_list: D011933:Reagent Kits, Diagnostic