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Pınar Bulutay



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    P38 - Pathology - Pathology/Staging (ID 108)

    • Event: WCLC 2020
    • Type: Posters
    • Track: Pathology, Molecular Pathology and Diagnostic Biomarkers
    • Presentations: 1
    • Moderators:
    • Coordinates: 1/28/2021, 00:00 - 00:00, ePoster Hall
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      P38.01 - The Role of Pathology in The Proposed Subdivided N Descriptors of The TNM Staging System For Lung Cancer– A Single Center Experience (ID 2300)

      00:00 - 00:00  |  Presenting Author(s): Pınar Bulutay

      • Abstract
      • Slides

      Introduction

      IASLC has proposed to subdivide N descriptors of TNM Staging for lung cancer into N1a (single N1 station), N1b (multiple N1 stations), N2a1 (skip metastases), N2a2 (single N2 with N1 involvement) and N2b (multiple N2 stations). The lymph nodes (LNs) on resection specimens have been dissected and reported separately according to their stations in our department over the years. The aim of this study is to evaluate the survival differences between pathologically confirmed subdivided N descriptors and to examine the value of other parameters related to N1 LNs such as the number of metastasis in a single LN station, size of the largest metastasis, extranodal invasion, and metastasis defined by direct infiltration of the primary tumor.

      Methods

      The analysis was conducted on data from 630 NSCLC patients who underwent surgical treatment between 2008-2019. The IASLC nodal map and anatomical definitions were used to describe regional lymph node stations. Survival analysis was done with Kaplan Meier method.

      Results

      Among 630 patients, 193 showed pathological nodal involvement (128 N1, 65 N2). The distribution of cases into the subdivided N categories were as follows: 437 were N0, 88 were N1a, 40 were N1b, 13 were N2a1, 42 were N2a2, and 10 were N2b. The mean number of LNs dissected by pathologists was 12.10±7.31, sampled by surgeons was 7.56±5.84. Overall survival (OS) rates of the subdivided N descriptors- regardless of T stage, histologic type, adjuvant therapy- were significantly different: 85.9% for N0, 77.2% for N1a, 66.1% for N1b, 76.2% for N2a1, 33.5% for N2a2 and 44.4% for N2b (p<0.001). Multiple LN station involvement is found to be an unfavorable prognostic sign both for N1 and N2 cases (N1a vs N1b) (N2a1 vs N2a2, N2b). Patients with only single N2 involvement (skip metastasis) had a better OS then multiple N1 involvement (N2a1 vs N1b) (p<0.001). Among N1 cases (n:128) the number of involved LNs in a single station (1 LN/ >1 LN), extracapsular invasion (absent/ present), and the size of the largest metastasis did not show any significant difference in survival rates (p>0.005). Patients having metastases in distally located N1 stations (13, 14), and metastasis defined by direct extension of the primary tumor into the lymph nodes showed a favorable survival; all patients were alive. However, statistical analysis could not be done for these groups due to the limited number of cases.

      Conclusion

      Evaluation of N1 LNs is under the responsibility of pathologists; they should be dissected and reported according to their stations. As proposed by IASLC, single or multiple N1 station involvement shows a survival difference. In contrast, presence of one or more metastatic lymph nodes in a single N1 station does not seem to have a prognostic value. Distal or proximal LN involvements, LN metastasis caused by direct infiltration of the primary tumor may have an effect on survival. Studies in larger multi-institutional series should be conducted. In addition, the favorable prognosis of N2a1 cases in our series is remarkable and should further be evaluated in detail.

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