Author of

• 25946

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  P2.09 - Pathology (Not CME Accredited Session) (ID 958)

  • Event: WCLC 2018
  • Type: Poster Viewing in the Exhibit Hall
  • Track:
  • Presentations: 1
  • Moderators:
  • Coordinates: 9/25/2018, 16:45 - 18:00, Exhibit Hall

  • 27066

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    P2.09-12 - EGFR Mutation Status in Squamous Cell Carcinoma or Non-Small Cell Carcinoma Favor Squamous Cell Carcinoma Diagnosed from Small Lung Biopsies (ID 13154)

    16:45 - 18:00  |  Presenting Author(s): Hsiang-Ling Ho
    • Abstract

    Background
    

    Epidermal growth factor receptor (EGFR) mutation testing is strongly recommended in non-small cell lung cancer (NSCLC) patients with adenocarcinoma subtypes, or patients with mixed-type tumors containing adenocarcinomatous components. However, in clinical practice, patients showing squamous cell carcinoma (SqCC) morphology on small biopsies cannot be ruled out to have an adenocarcinomatous component elsewhere in the lesion due to sampling bias. Therefore, EGFR mutation testing may have been neglected in such circumstances, which would affect the clinical management of patients. In this study, we sought to examine the frequency of EGFR mutations in lung cancer patients with SqCC or Non-Small Cell Carcinoma (NSCC) favor SqCC diagnosed from small biopsies. The correlation between EGFR mutation status and clinicopathological characteristics was also evaluated.

    a9ded1e5ce5d75814730bb4caaf49419 Method
    

    One hundred and forty-eight patients diagnosed as SqCC or NSCC favor SqCC from small lung biopsies were enrolled. All of these cases were histologically confirmed by evaluating cellular morphology using hematoxylin-eosin (HE) staining and TTF1, p40 or CK5/6 expression using immunohistochemistry. EGFR mutations were examined using real-time PCR based assay.

    4c3880bb027f159e801041b1021e88e8 Result
    

    Among 148 small biopsy cases, 135 (91.2%) were diagnosed as SqCC while 13 (8.8%) were NSCC favor SqCC. Approximately 8.8% (13/148) of all cases were found to have EGFR mutations, including 7 (53.8%) L858R mutation, 4 (30.8%) exon 19 deletion, and 2 (15.4%) cases with coexistent L858R and T790M mutations. EGFR mutation-positive cases accounted for 5.2% (7/135) in SqCC, 46.2% (6/13) in NSCC favor SqCC, and 83.3% (10/12) of all these cases were never smokers. The multivariate analysis showed that EGFR mutations were more prevalent in non-smokers than those in smokers (83.3% versus 16.7%, p = 0.03) and in patients diagnosed as NSCC favor SqCC than in those diagnosed as SqCC (46.2% versus 5.2%, p = 0.002). In addition, 4 out of 13 EGFR mutation-positive patients with SqCC or NSCC favor SqCC morphology were eventually diagnosed as adenosquamous carcinoma after further undergoing surgical resection.

    8eea62084ca7e541d918e823422bd82e Conclusion
    

    To the best of our knowledge, this is the first study directly addressing the importance of EGFR mutation testing in lung cancer patients with SqCC or NSCC favor SqCC diagnosed from small biopsies. Our findings suggest that EGFR mutation testing should not be excluded in such populations, especially in never-smokers, or patients with NSCC favor SqCC subtypes.

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