Author of

• 11866

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  P2.18 - Poster Session 2 - Pathology (ID 176)

  • Event: WCLC 2013
  • Type: Poster Session
  • Track: Pathology
  • Presentations: 1
  • Moderators:
  • Coordinates: 10/29/2013, 09:30 - 16:30, Exhibit Hall, Ground Level

  • 11868

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    P2.18-002 - A comprehensive comparative analysis of the histomorphological features of ALK-rearranged lung adenocarcinoma based on driver oncogene mutations : frequent expression of epithelial-mesenchymal transition markers than other genotype (ID 221)

    09:30 - 09:30  |  Author(s): H. Kim
    • Abstract

    Background
    Molecular classification of lung cancer correlates well with histomorphologic features. However, detailed histomorphologic features which differentiate ALK rearranged tumors from ALK wild type has not been fully evaluated. To investigate histomorphologic features of tumors harboring ALK rearrangement to evaluate the predictive significance of morphologic characterization, we compared the histomorphological analysis between ALK-rearranged and ALK negative lung adenocarcinomas based on driver oncogene mutations.

    Methods
    Eighty resected ALK rearranged lung adenocarcinomas and two hundred thirteen resected ALK negative adenocarcinomas (91 EGFR mutated, 29 K-ras mutated and 93 triple-negative) were analyzed for several histomorphological parameters and histologic subtype based on newly proposed IASLC/ATS/ERS classification.

    Results
    ALK rearranged tumors were associated with a younger age at presentation, frequent nodal metastasis and higher stage at diagnosis, compared with patients with other genotypes. ALK rearranged tumors were more likely to show solid predominant pattern (43.8%, 35/80) than other genotypes (p<0.001) and a lepidic predominant histology was not observed in ALK rearranged tumors (p<0.001). In ALK rearranged tumors, considerable number of the tumors (67.5% , 54/80) contained at least 5% solid pattern but only small number of the tumors (12.5%, 12/80) contained at least 5% lepidic pattern, compared with other genotypes (p<0.001). The most significant morphological features distinguishing ALK rearranged tumors from ALK negative tumors were cribriform formation (OR: 3.253, p=0.028), presence of mucin-containing cells (OR: 4.899, p=0.008), close relation to adjacent bronchioles (OR: 5.361, p=0.001), presence of psammoma body (OR: 4.026, p=0.002) and solid predominant histological subtype (OR: 13.685, p=0.023). ALK-rearranged tumors exhibited invasive histomorphological features, aggressive behavior and frequent expression of epithelial-mesenchymal transition markers (loss of E-cadherin and expression of vimentin) compared with other genotype (p =0.015). Spatial proximity between bronchus and ALK-rearranged tumors and frequent solid histologic subtype with p63 expression may cause diagnostic difficulties to differentiate squamous cell carcinoma in the small biopsy, whereas p40 was rarely expressed in ALK-rearranged adenocarcinoma.

    Conclusion
    Knowledge of these features may improve the diagnostic accuracy and lead to a better understanding of the characteristic behavior of ALK-rearranged tumors.