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• 30064

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  MA10 - Emerging Technologies for Lung Cancer Detection (ID 129)

  • Event: WCLC 2019
  • Type: Mini Oral Session
  • Track: Screening and Early Detection
  • Presentations: 1
  • Now Available
  • Moderators:Fabrizio Bianchi, Marcelo Sanchez
  • Coordinates: 9/08/2019, 15:15 - 16:45, Dublin (1997)

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    MA10.11 - Sensitivity and Optimal Clinicopathological Features of Genetic Targeted Liquid Biopsy in pN0M0 Lung Adenocarcinoma (Now Available) (ID 788)

    15:15 - 16:45  |  Author(s): Naoto Kishi
    • Abstract
    • Presentation
    • Slides

    Background
    

    Liquid biopsy for diagnosis of early-stage lung cancer is still challenging. The optimal marker and methodology has not been established. In Asia, almost 40-50% of lung adenocarcinomas harbor the EGFR mutation and L858R is a representative of a somatic EGFR mutation. We evaluated the usefulness of the EGFR somatic mutation in liquid biopsy using droplet digital PCR (ddPCR), which is a sensitivity device to detect several types of genetic mutations.

    Method
    

    We examined weather L858R could be detected from preoperative ctDNA by ddPCR. Cases without EGFR mutation (wild type) were utilized as negative control. All involved cases underwent surgical resection after preoperative HRCT and PET-CT. Serum for ctDNA extraction was collected before the operation. L858R in the primary site was confirmed by resected surgical specimen. Clinicopathological features (e.g.: whole and invasive tumor size on HRCT, SUV max on PET-CT, histological subtype) were also explored for an optimal liquid biopsy candidate.

    Result
    

    Forty-five pN0M0 lung adenocarcinoma patients harboring L858R were enrolled. Twenty-one and 24 cases showed part-solid and pure solid appearance on HRCT, respectively. Median whole and invasive tumor size on HRCT was 21 and 19 mm, respectively. 91.1% (41/45) cases were clinical stage IA1-IB and 97.8% (44/45) cases were pathological stage IA1-IB. In wild type cases, positive droplet for L858R was almost completely undetectable. Whereas, L858R was significantly detected in 7 EGFR mutant cases (sensitivity is 15.56%, 7/45). Among 7 positive cases, 6 cases showed pure solid appearance in preoperative HRCT. Except for pure solid appearance, there was no significant features related to the positive result. If cases are limited to pure solid appearance, 25.0% (6/24) of cases could be diagnosed by liquid biopsy. Even small-sized tumors (1.1 cm in diameter) or tumors with slight accumulation on PET-CT (SUV max 0.5) could be detected if it showed pure solid appearance on HRCT.

    Conclusion
    

    L858R can be a definitive marker for liquid biopsy using ddPCR in pN0M0 lung adenocarcinoma. 15.56% (7/45) of cases were diagnosed in pN0M0 cases. Limited to pure solid tumor, 25.0% (6/24) could be detected. Liquid biopsy can be a useful diagnostic option, especially for tumors with pure solid appearance.

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