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U. Dafni

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    MO10 - Molecular Pathology II (ID 127)

    • Event: WCLC 2013
    • Type: Mini Oral Abstract Session
    • Track: Pathology
    • Presentations: 1
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      MO10.07 - ALK immunohistochemistry and fluorescence in-situ hybridization in Lung adenocarcinomas from the ETOP Lungscape tumour cohort (ID 2267)

      16:15 - 17:45  |  Author(s): U. Dafni

      • Abstract
      • Presentation
      • Slides

      The European Thoracic Oncology Platform LungScape database contains 2614 cases of primary resected lung carcinoma from 16 centres with patient demographics, pathological tumour data and detailed clinical follow-up. A total of 1281 cases of adenocarcinoma with >2 years clinical follow-up were selected for analysis of ALK status by immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH). Test positive cases were matched, in order of importance at ratio 1:2, by stage, gender, smoking status, study centre, year of surgery and age with test negative cases -both for IHC and for FISH testing.

      Testing was performed in all centres using the same protocol (IHC: Novocastra 5A4 clone antibody at 1:10 dilution, Novolink detection system. FISH: Abbott Vysis ALK break-apart probe). Each centre passed an external QA test using unknown cases in a tissue microarray before conducting the LungScape tumour testing. IHC was scored according to three intensity scores (1+, 2+, 3+) using ‘objective’ methodology previously described [1]. Maximum staining intensity was recorded. Any IHC staining was defined as IHC positive result. FISH preparations were assessed according to the Vysis protocol on all 82 IHCpositive cases plus their 164 IHCnegative matches.


      IHC cases, n=1281 FISH positive(264 tested)
      IHC negative 1199 (93.6%) 0 (0.0% of 164 controls) FISH specificity: 100%
      IHC 1+ 43 (3.35%) 2 (4.6% of IHC 1+)
      IHC 2+ 16 (1.25%) 6 (37.5% of IHC 2+)
      IHC 3+ 23 (1.8%) 20 (87% of IHC 3+)
      IHC any positive 82 (6.4%) 28 (34.1% of IHC+) FISH sensitivity: 34.1%
      FISH sensitivity was 87% for IHC 3+. IHCpositive/FISHnegative cases (n=54) were mostly IHC 1+ (75.9%), sometimes IHC 2+ (18.5%) and rarely IHC 3+ (5.5%). The frequency of never smokers was higher in the ALK IHCpositive group (29.3%) versus IHCnegative group (18.3%) {p=0.011}. Age, gender and tumour stage did not differ between IHC groups. The hazard of an event for IHCpositive cases decreases by 32% in relapse-free survival {RFS; p=0.03} and by 38% in either time-to-relapse {TTR; p=0.02} or overall survival {OS; p=0.016}. Multivariate models -adjusted for patient and tumour characteristics- indicated that IHC-ALK was a significant predictor for all three time-to-event outcomes (RFS, TTR, OS). In stratified Cox analysis, significantly higher OS was retained in the IHCpositive (HR=0.59, p=0.04) and FISHpositive (HR=0.34, p=0.03) cases in the matched cohorts, while conditional logistic regression yielded non-significant associations with 3-year survival status.

      In this large cohort of surgically resected primary lung adenocarcinoma: ALK IHC positivity was 6.4%. IHC 3+ staining (prevalence 1.8%) showed 87% probability of ALK FISH positivity ALK IHC positivity was higher in never smokers and related to better clinical outcome ALK testing can be reliably implemented across multiple laboratories {1} Ruschoff et al. Virchows Arch. 2010;457(299-307).

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