title: Histologic subtypes, immunohistochemistry, FISH or molecular screening for the accurate diagnosis of ALK-rearrangement in lung cancer: a comprehensive study of Caucasian non-smokers.
abstract: EML4-ALK adenocarcinomas constitute a new molecular subgroup of lung tumours that respond very well to crizotinib, an ALK inhibitor. However, the diagnosis of ALK rearrangement in lung cancer is challenging. The aim of this study was to compare the diagnostic accuracy of five different methods in a series of 20 EGFR(wt/wt) lung adenocarcinomas from non- or light- smokers. Multiplex RT-PCR was considered as gold standard and identified four ALK-rearranged tumours among the 20 tested tumours. qRT-PCR got an interpretability rate of 100% and accurately typed all 20 tumours. qRT-PCR from corresponding formalin-fixed paraffin-embedded (FFPE) specimens got an interpretability rate of 65%. Out of the four previously identified ALK-rearranged cases, three were interpretable and two were retrieved using FFPE qRT-PCR. ALK break-apart FISH got an interpretability rate of 60% and accurately typed all of the twelve remaining cases. Anti-ALK immunohistochemistry (IHC) accurately typed all twenty tumours using a cut-off value of strong staining of 100% tumour cells. The 16 non ALK-rearranged tumours got no/light staining in 13 cases, and a moderate staining of 80-100% tumour cells in 3 cases. We then analysed four solid signet-ring lung adenocarcinomas. FFPE qRT-PCR, FISH and immunohistochemistry were concordant in three cases, with positive and negative results in respectively one and two cases. The fourth case, which was positive by FISH and immunohistochemistry but negative by RT-PCR, was shown to have a non-EML4-ALK ALK-rearrangement. As various factors such as RNA quality, fixation quality and type of ALK rearrangement may impede ALK screening, we propose a combined FISH/molecular biology diagnostic algorithm in which anti-ALK immunohistochemistry is used as a pre-screening step.
authors.affiliation: APHP, Université Paris Descartes, Groupe Hospitalier Cochin-Broca-Hôtel Dieu, Service d'anatomie et de cytologie pathologiques, Paris, F-75014, France.
authors.forename: Pierre-Alexandre
authors.initials: PA
authors.lastname: Just
authors.forename: Aurélie
authors.initials: A
authors.lastname: Cazes
authors.forename: Anne
authors.initials: A
authors.lastname: Audebourg
authors.forename: Anatole
authors.initials: A
authors.lastname: Cessot
authors.forename: Karine
authors.initials: K
authors.lastname: Pallier
authors.forename: Claire
authors.initials: C
authors.lastname: Danel
authors.forename: Marie-Cécile
authors.initials: MC
authors.lastname: Vacher-Lavenu
authors.forename: Pierre
authors.initials: P
authors.lastname: Laurent-Puig
authors.forename: Benoît
authors.initials: B
authors.lastname: Terris
authors.forename: Hélène
authors.initials: H
authors.lastname: Blons
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis* / Q000235:genetics*; D000368:Aged; D000369:Aged, 80 and over; D000077548:Anaplastic Lymphoma Kinase; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D008175:Lung Neoplasms / Q000175:diagnosis* / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014178:Translocation, Genetic; D044465:White People
chemical_list: C000626173:ALK protein, human; D000077548:Anaplastic Lymphoma Kinase; D020794:Receptor Protein-Tyrosine Kinases