Author of

• 11595

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  P2.07 - Poster Session 2 - Surgery (ID 190)

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

  • 11620

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    P2.07-025 - New pathological classification of lung adenocarcinoma is useful for selecting limited cases undergoing sublobar resection as a curative surgery. (ID 2254)

    09:30 - 09:30  |  Author(s): K. Uchida
    • Abstract

    Background
    A new lung adenocarcinoma classification is being proposed by the International Association for the Study of Lung Cancer, American Thoracic Society, and European Respiratory Society (IASLC/ATS/ERS), which was based on histomorphologic subtype and had recently been validated in a North American series of 514 stage I lung adenocarcinomas. However, its distribution of patient number was biased, especially adenocarcinoma in situ (AIS), minimally invasive adenocarcinoma (MIA), and non-mucinous lepidic predominant groups, compared with in Japan. We evaluated an appropriateness of new classification in a series in Japan and whether the classification could be useful for selecting limited cases undergoing sublobar resection.

    Methods
    We retrospectively reviewed clinical records of all patients operated on for non-small cell lung cancer from 1997 to 2011 (n=825). 292 patients (35.4%) had pathological stage IA adenocarcinoma of the lung classified according to the Union for International Cancer Control/American Joint Committee on Cancer 7th Edition. Some pathologists, blinded to patient outcome, performed histopathologic subtyping according to the proposed new IASLC/ATS/ERS classification. Statistical analyses were made including Kaplan–Meier and Cox regression analyses.

    Results
    There were 160 females (54.8%) and 132 males (45.2%) with a median age of 67 years (29–84 years) and 212 pT1a and 80 pT1b patients (tumor size: 16.7±7.1 [2-30] mm). Three overall prognostic groups were identified: low grade: AIS (n=103, 35.3%) and MIA (n=24, 8.2%) had 97.1% and 95.1% of disease-free survival at 5 years (DFS, median follow-up was 54 months); intermediate grade: non-mucinous lepidic predominant (n=61, 20.9%), acinar predominant (n=38, 13.0%), and papillary predominant (n=48, 16.4%), with 80.1%, 86.5%, and 62.4% of DFS; and high grade: invasive mucinous adenocarcinoma (n=5, 1.7%), solid predominant (n=12, 4.1%) and micropapillary predominant (n=1, 0.3%), with 88.9% of DFS. DFS in low grade was significant better than in other two grades (P<0.005), however, there was no significant difference between in intermediate and high grade groups due to lower DFS in papillary predominant or insufficient patient number in high grade group. Preoperative imaging examinations such as consolidation/tumor (C/T) ratio on high resolution CT and maximum standardized uptake value (SUVmax) by FDG-PET were correlated with histopathologic grade according to new classification (P<0.01). Moreover, sublobar resection was undergone for 144 cases (49.3%), more cases had been identified small tumor, low C/T ration, low SUVmax, and low grade subtypes, and DFS in sublobar resection was 96.4% which was significant better than in lobectomy (78.6%, P=0.0002).

    Conclusion
    In this study, we can evaluate with enough number of patients classified to AIS, MIA, or non-mucinous lepidic predominant according to the new IASLC/ATS/ERS classification. Most of subtypes correlated with DFS, except of papillary predominant and subtypes in high grade clinical aggressiveness, which may need more clinical investigation. Patients in low grade subtypes who underwent sublobar resection had better DFS, which can be predicted using tumor size and preoperative imaging examinations such as C/T ratio and SUVmax. So, the new classification has advantages for better selection of limited cases undergoing sublobar resection as a curative surgery.