Author of

• 20135

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  MA 17 - Locally Advanced NSCLC (ID 671)

  • Event: WCLC 2017
  • Type: Mini Oral
  • Track: Locally Advanced NSCLC
  • Presentations: 1
  • Moderators:S. Jheon, Georgios Stamatis
  • Coordinates: 10/17/2017, 15:45 - 17:30, F203 + F204 (Annex Hall)

  • 23782

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    MA 17.13 - Impact of Histologic Subtype of Locally Advanced Lung Adenocarcinoma on Outcomes After Definitive Chemoradiation (ID 10382)

    15:45 - 17:30  |  Author(s): S.H. Patel
    • Abstract
    • Presentation
    • Slides

    Background:
    Micropapillary and solid subtypes of lung adenocarcinoma have significantly worse outcomes and survival after surgical resection for early-stage disease. These subtypes have recently been shown to have higher locoregional and metastatic progression after definitive stereotactic radiation therapy (SBRT) as well. However, the potential impact of histologic subtype on locally advanced disease treated with definitive concurrent or sequential chemoradiation (CRT) has not been previously explored. We sought to identify high-risk subtype patients treated with CRT, and compare their outcomes with those not known to have high-risk histologic subtypes.
    
    Method:
    We identified 249 consecutive patients with stage IIIA-B lung adenocarcinoma who had undergone CRT at our institution from 2008 to 2015. All patients had pathology reviewed by pathologists at our institution with subspecialty expertise in thoracic pathology. Twenty-five patients had elements of micropapillary and/or solid subtype on core biopsy, according to the 2015 World Health Organization classification. The remaining 224 patients were considered non-high-risk (8 patients had core biopsy with no high-risk subtypes identified; 216 patients either did not undergo core biopsy or did not have subtyping performed). Local, nodal, regional, and distant failure were estimated using cumulative incidence (CI) curves and compared using the log-rank test. Time to each event was measured from the date of diagnosis until the event of interest or the last follow-up visit.
    
    Result:
    With median followup of 19.7 months, there was a trend towards greater 2-year CI of local failure in the high-risk vs. non-high-risk group (40.7% vs. 26.7% p=0.060). The 2-year CI of nodal, regional, and distant failure in high-risk versus non-high-risk groups was 30.9% vs. 32.6% (p=0.576), 24.7% vs. 20.1% (p=0.468), and 63.9% vs. 59.8% (p=0.272), respectively, though statistical power was limited due to the small number of known high-risk patients.
    
    Conclusion:
    Though only a limited proportion of patients had demonstrated high-risk subtypes in this cohort, there was a trend towards earlier local failure in locally advanced adenocarcinoma patients treated with definitive concurrent or sequential chemoradiation, similar to what has been observed for early-stage tumors treated with SBRT. Hence, high-risk histologic subtype may be a prognostic factor for early treatment failure in locally advanced adenocarcinoma patients treated with CRT. We suggest that core biopsies, which are required for histologic subtyping, should be obtained more often in these patients, to allow for further study of the hypothesis that histologic subtype predicts outcomes after definitive chemoradiation.
    
    

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