title: Bright-field dual-color chromogenic in situ hybridization for diagnosing echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase-positive lung adenocarcinomas.
abstract: BACKGROUND
  A subset of lung cancers harbors an EML4-ALK (echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase) gene fusion, and detecting this subset may hold therapeutic implications. Many prior studies used fluorescence in situ hybridization (FISH) analysis for this detection, but FISH may have disadvantages including signal decay and dark-field examination that may obscure tissue architecture. In this study, we explored the potential of the ALK-break-apart chromogenic in situ hybridization (CISH) method to detect ALK-rearranged lung cancer.
  
  
  METHODS
  We examined 15 lung adenocarcinomas with reverse-transcriptase polymerase chain reaction-proven EML4-ALK fusion transcripts and 30 ALK-negative cases. One hundred tumor cells were evaluated by CISH and FISH for each case, and a detailed signal profile was recorded and compared.
  
  
  RESULTS
  CISH preserved tissue architecture and cytomorphology considerably and facilitated the signal evaluation using a routine light microscope. Positive rearrangement signals (splits or isolated 3' signals) were identified in 13 to 78% (mean ± SD, 41% ± 19%) of tumor cells in the ALK-positive cohort and in 0 to 15% (mean ± SD, 6% ± 4%) of cells in the ALK-negative cohort. The two groups were best separated by a cutoff value of 20%, with a sensitivity of 93% and a specificity of 100%. The only false-negative tumor having only 13% CISH-positive cells displayed predominantly (76%) isolated 5' signals unaccompanied by 3' signals. FISH showed largely similar signal profiles, and the results were completely concordant with CISH.
  
  
  CONCLUSIONS
  We have successfully introduced CISH for diagnosing EML4-ALK-positive lung adenocarcinoma. This method allows simultaneous visualization of genetics and tumor cytomorphology and facilitates the molecular evaluation and could be applicable in clinical practice to detect lung cancer that may be responsive to ALK inhibitors.
authors.affiliation: *Department of Pathology and Clinical Laboratories, National Cancer Center Hospital, Japan.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Yoshida
authors.forename: Koji
authors.initials: K
authors.lastname: Tsuta
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Nitta
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Hatanaka
authors.forename: Hisao
authors.initials: H
authors.lastname: Asamura
authors.forename: Ikuo
authors.initials: I
authors.lastname: Sekine
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Grogan
authors.forename: Masashi
authors.initials: M
authors.lastname: Fukayama
authors.forename: Tatsuhiro
authors.initials: T
authors.lastname: Shibata
authors.forename: Koh
authors.initials: K
authors.lastname: Furuta
authors.forename: Takashi
authors.initials: T
authors.lastname: Kohno
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Tsuda
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D002863:Chromogenic Compounds; D015331:Cohort Studies; D006801:Humans; D007124:Immunoenzyme Techniques; D017404:In Situ Hybridization, Fluorescence; D008175:Lung Neoplasms / Q000175:diagnosis* / Q000235:genetics* / Q000378:metabolism; D015514:Oncogene Proteins, Fusion / Q000235:genetics* / Q000378:metabolism*; D011379:Prognosis; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D046888:Tissue Array Analysis
chemical_list: D002863:Chromogenic Compounds; C522504:EML4-ALK fusion protein, human; D015514:Oncogene Proteins, Fusion; D012333:RNA, Messenger