title: Heterogeneity of anaplastic lymphoma kinase gene rearrangement in non-small-cell lung carcinomas: a comparative study between small biopsy and excision samples.
abstract: BACKGROUND
  The standard diagnostic method for echinoderm microtubule-associated protein-like 4-anaplastic lymphoma receptor tyrosine kinase translocation is fluorescence in situ hybridization (FISH). Recently, immunohistochemistry (IHC) has been reported as a potential method in screening for anaplastic lymphoma kinase (ALK)-positive non-small-cell lung carcinomas (NSCLC), whereas several authors have reported a discordance between FISH and IHC results. We investigated the heterogeneity of ALK gene rearrangement in excision specimens by FISH and also examined whether the FISH score of ALK gene rearrangement corresponded in excision and biopsy samples from the same patient.
  
  
  METHODS
  Twenty ALK IHC-positive patients including six patients treated with crizotinib therapy were evaluated for the presence of ALK FISH. For evaluation of heterogeneity of ALK gene rearrangement in excision specimens, we defined six to 10 observation areas in each case, and the number of ALK FISH positive observation areas (≥15% rearrangement detected) was investigated. ALK FISH score in small biopsy samples was classified as positive (≥15% rearrangement detected), equivocal (5-14% rearrangement detected), or negative (<4% rearrangement detected).
  
  
  RESULTS
  Of a total of 64 tumor observation areas from nine excision specimens, 50 areas were positive for ALK gene rearrangement (81.8%). In the comparison of excision and small biopsy samples, all excision specimens were ALK FISH-positive (100%; 6 of 6), whereas only three of the small biopsy samples in these patients were positive (50%; 3 of 6), two were equivocal (33%; 2 of 6), and one was negative (17%; 1 of 6). The two equivocal patients received crizotinib and showed a response.
  
  
  CONCLUSIONS
  ALK gene rearrangement heterogeneity was observed in NSCLC specimens by FISH. Our findings suggested that IHC-positive/FISH-equivocal cases should not be considered true "false-negatives" when a small biopsy sample was used for ALK analysis.
authors.affiliation: Department of Diagnostic Pathology, Kurume University Hospital, Kurume, Japan. Electronic address: abe_hideyuki@kurume-u.ac.jp.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Abe
authors.affiliation: Department of Diagnostic Pathology, Kurume University Hospital, Kurume, Japan.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kawahara
authors.affiliation: Division of Respirology, Neurology, and Rheumatology, Department of Internal Medicine, Kurume University School of Medicine, Kurume, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Azuma
authors.affiliation: Department of Diagnostic Pathology, Kurume University Hospital, Kurume, Japan.
authors.forename: Tomoki
authors.initials: T
authors.lastname: Taira
authors.affiliation: Department of Diagnostic Pathology, Kurume University Hospital, Kurume, Japan.
authors.forename: Yorihiko
authors.initials: Y
authors.lastname: Takase
authors.affiliation: Department of Diagnostic Pathology, Kurume University Hospital, Kurume, Japan.
authors.forename: Chihiro
authors.initials: C
authors.lastname: Fukumitsu
authors.affiliation: Department of Diagnostic Pathology, Kurume University Hospital, Kurume, Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Murata
authors.affiliation: Department of Diagnostic Pathology, Kurume University Hospital, Kurume, Japan.
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Yamaguchi
authors.affiliation: Department of Pathology, Kurume University School of Medicine, Kurume, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Akiba
authors.affiliation: Division of Respirology, Neurology, and Rheumatology, Department of Internal Medicine, Kurume University School of Medicine, Kurume, Japan.
authors.forename: Hidenobu
authors.initials: H
authors.lastname: Ishii
authors.affiliation: Center for Clinical and Translational Research, Kyushu University Hospital, Fukuoka, Japan.
authors.forename: Isamu
authors.initials: I
authors.lastname: Okamoto
authors.affiliation: Division of Respirology, Neurology, and Rheumatology, Department of Internal Medicine, Kurume University School of Medicine, Kurume, Japan.
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Hoshino
authors.affiliation: Department of Surgery, Kurume University School of Medicine, Kurume, Japan.
authors.forename: Shinzou
authors.initials: S
authors.lastname: Takamori
authors.affiliation: Department of Diagnostic Pathology, Kurume University Hospital, Kurume, Japan.
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Kage
mesh_terms: D000328:Adult; D000368:Aged; D000077548:Anaplastic Lymphoma Kinase; D001706:Biopsy; D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics* / Q000473:pathology* / Q000601:surgery; D005188:False Negative Reactions; D005260:Female; D015321:Gene Rearrangement; D018740:Genetic Heterogeneity; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D008168:Lung / Q000473:pathology*; D008175:Lung Neoplasms / Q000235:genetics* / Q000473:pathology* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D020794:Receptor Protein-Tyrosine Kinases / Q000032:analysis / Q000235:genetics*
chemical_list: C000626173:ALK protein, human; D000077548:Anaplastic Lymphoma Kinase; D020794:Receptor Protein-Tyrosine Kinases