Author of

• 12824

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  P3.21 - Poster Session 3 - Diagnosis and Staging (ID 171)

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

  • 12830

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    P3.21-006 - The N-classification Based on the Number of Metastatic Lymph Node is Superior to Regional N-classification in Predicting Outcomes After Surgical Resection for Non-small Cell Lung Cancer. (ID 1764)

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

    Background
    In many cancers, the N-classification of current TNM stage is categorized by the number of positive lymph nodes. However, for non-small cell lung cancer (NSCLC), it is classified by the involvement of specific regional node groups. The aim of this study is to make a new N-classification grouping (nN stage) based upon the number of metastatic lymph nodes and to evaluate its prognostic significance in predicting outcome after resection of NSCLC.

    Methods
    Between January 2000 and April 2011, 2319 patients underwent surgery for NSCLC in our hospital. A total of 1982 patients was selected by excluding patients who received preoperative induction therapy or did not get curative resection and those with pN3 metastatic lymph nodes. Prospectively collected clinical information as well as pathologic variables were retrospectively analyzed. The recursive partitioning analysis was applied to define the most significant cut-off number of metastatic lymph nodes. We then analyzed overall and disease-free survival using the new nN stage grouping to test if it can provide more accurate classification compared to the conventional N stage grouping.

    Results
    Recursive partitioning analysis identified patients could be divided into three distinct groups according to the number of metastatic lymph nodes: nN0 (none), nN1 (1-7), nN2 (>7). Among 1982 patients, 1371 patients were nN0, 538 were nN1, and 73 were nN2. The 5-year overall survival rates were 79.8%, 62.1% and 36.1% for nN0, nN1, and nN2, respectively, and they were statistically different (p < 0.001, log-rank test). For conventional N stage, 1371 patients were pN0, 284 were pN1, and 327 were pN2. The 5-year survival rates were 79.8%, 63.8%, and 54.8% for pN0, pN1, and pN2 stages, respectively (p < 0.001, log-rank test). The chi-square value of nN stage was superior to that of pN stage (141.02 vs. 117.16). When we further analyzed those with pN2 patients, the nN1/pN2 group showed a significantly better survival rate than nN2/pN2 group (p < 0.001, log-rank test). Moreover, the overall survival of nN1/pN2 patients was not different from that of nN1/pN1 patients. (p = 0.074, log-rank test) Figure 1

    Conclusion
    The nN-classification seemed to predict long-term survival more accurately compared to conventional N stage grouping. Our result suggested the new N stage grouping based on the number of metastatic lymph node should be considered for the next revision of the TNM classification system for NSCLC.