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  P1.09 - Pathology (Not CME Accredited Session) (ID 941)

  • Event: WCLC 2018
  • Type: Poster Viewing in the Exhibit Hall
  • Track:
  • Presentations: 1
  • Moderators:
  • Coordinates: 9/24/2018, 16:45 - 18:00, Exhibit Hall

  • 26509

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    P1.09-08 - Integrating NGS Information for Staging Multiple Lung Adenocarcinoma: A McGill University Health Centre Retrospective Study. (ID 12635)

    16:45 - 18:00  |  Author(s): Leon van Kempen
    • Abstract
    • Slides

    Background
    

    The incidence of patients with multiple primary lung adenocarcinoma (MPLC) is increasing and the optimal management of these patients remains unclear. Distinguishing between MPLC and intrapulmonary metastases is at the heart of the diagnostic dilemma. The Comprehensive Histologic Assessment (CHA) relies on microscopic examination including histological subtypes, cytological and stromal features. CHA has shown a good reproducibility but with a non-negligible rate of disagreement, even between expert pathologists. Moreover, predictive biomarker testing has become standard of care for lung cancer patients and the use of Next-Generation Sequencing (NGS) is now widely available. The goal of this study was to evaluate how the NGS information may be integrated in the diagnostic strategy for distinguishing between MPLC and patients with stage III/IV disease.

    a9ded1e5ce5d75814730bb4caaf49419 Method
    

    We conducted a retrospective study of all surgical patients with > 1 synchronous lung carcinoma over two years. We identified 59 cases and reviewed initial clinical, pathological and molecular reports. Patients having multifocal lung adenocarcinoma with prominent lepidic component or an adenocarcinoma associated with another histological type were considered as synchronous primaries and not tested for molecular aberrations. The NGS panel analysis using an Illumina miSeq platform included the following genes: AKT1, BRAF, EGFR, ERBB2, FOXL2, GNA11, GNAQ, KIT, KRAS, MET, NRAS, PDGFRA, PIK3A, RET, and TP53.

    4c3880bb027f159e801041b1021e88e8 Result
    

    Histologically, the majority were considered as MPLC with only four suspected metastases. Twenty-five patients had adenocarcinoma with prominent lepidic component and one case had two different histological differentiations (adenocarcinoma and squamous cell carcinoma). Most of the suspected synchronous primary tumours had different mutations in the separate tumours. Relevant mutations were found in KRAS and P53 genes, with fewer mutations in EGFR, PIK3CA and BRAF genes, in accordance with known frequencies. In 12% of the cases, the NGS was not informative with no molecular mutation in either tumours. One case was reclassified from MPLC to intra-pulmonary metastases and restaged after NGS. For one patient, a TP53 mutation allowed us to reclassify two nodules as metastases from a previous adenocarcinoma originally diagnosed in 2012. In one patient having three separate nodules, different KRAS and TP53 mutations allowed the diagnosis of two nodules as intrapulmonary metastases and one contralateral nodule as synchronous primary adenocarcinoma.

    8eea62084ca7e541d918e823422bd82e Conclusion
    

    Although CHA is an efficient method for diagnosing MPLC from intra-pulmonary metastases there are still difficult cases with a risk of misdiagnosis. Integrating NGS analysis in the diagnostic strategy may lead to improved quality and accuracy in the staging of MPLC.

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