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

  • 11615

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    P2.07-020 - Clinicopathological characteristics of patients with unexpected pathological N1 and N2 lung cancer (ID 1762)

    09:30 - 09:30  |  Author(s): Y. Takagi
    • Abstract

    Background
    Although positron emission tomography/computed tomography (PET/CT) seems to be able to provide accurate information of lymph nodes status in non-small cell lung cancer (NSCLC) patients, we sometimes experience surgical cases with unexpected lymph nodes metastasis. The objective of this study is to demonstrate clinicopathological characteristics of patients with unexpected pathological (p) N1 and N2 NSCLC.

    Methods
    All patients with lung cancer underwent enhanced CT of the chest and PET/CT preoperatively for evaluating of lymph node status. Mediastinoscopy or EBUS-TBNA was not routinely performed. Unexpected pN1 and pN2 diseases were defined as surgical cases which were proved to have hilar or mediastinal lymph nodes metastasis postoperatively in spite of negative 18-fluoro-2-deoxy-D-glucose (FDG) uptake in hilar or mediastinal lymph nodes on preoperative PET/CT. We retrospectively reviewed clinical features of these patients and analyze predictive factors for these unexpected diseases.

    Results
    Between January 2007 and December 2012, 533 patients with lung cancer underwent　surgical resection at our institution. Among them, we reviewed 182 patients who had available preoperative PET/CT data and underwent a curative-intent operation with systematic or selective lymph node dissection. One hundred fifty-one patients (83%) had lung cancer with expected lymph node status, whereas, 31 patients (17%) were found to have lung cancer with unexpected lymph nodes metastasis, consisting of 12 (39%) unexpected pN1 and 19 (61%) unexpected pN2 diseases. There were 16 men and 15 women with a median age of 67 years. Seventeen patients were current- or past- smokers, and 14 were never-smokers. Tumor size ranged from 12 to 52 mm, and pathological T factor was pT1a in 3, pT1b in 5, pT2a in 19, pT2b in 3, and pT3 in 1. Histological type of the primary tumor were adenocarcinoma in 28 (90%), squamous cell carcinoma in 2, and large cell carcinoma in 1. Among 28 adenocarcinomas, the most common predominant subtype was papillary (20 patients; 71%), followed by acinar (5 patients), solid with mucin, micropapillary, and invasive mucinous (one patient, respectively). Of these patients, 7 patients had micropapillary component in varying proportions in their tumors. EGFR gene mutation status was available in 22 patients, and of these, 12 patients (55%) had tumors with EGFR gene mutation, consisting of exon 19 deletion in 5, exon 21 point mutation in 5, and other minor mutation in 1. In univariate analysis, tumor size (> 3cm), pleural, and lymphatic invasion were significant predictive factors for unexpected pN1 and pN2 diseases. Only in 151 adenocarcinomas, papillary predomiant tumor and having micropapillary component were significant predictive factors for unexpected lymph node metastasis.

    Conclusion
    We should take care that false-negative rate is relatively high on preoperative PET/CT for lymph node status in NSCLC. Histological findings of the primary tumor are often important because they can provide predictive information for lymph nodes status even if there is no FDG uptake in regional lymph nodes on preoperative PET/CT. We hope new accurate imaging modality which can reflect tumor histology and lymph nodes micrometastasis.