[A modified pathological N1 classification strategy based on the systematic dissection of N1 nodes for non-small cell...

The Tumor, Node, Metastasis (TNM) staging system has been adopted by the Union for International Cancer Control (UICC) and the American Joint Committee on Cancer (AJCC) for approximately 50 years. The N1 descriptor has rarely been modified since it was first proposed. Nevertheless, heterogeneity of the N1 disease should be prioritized because the survival outcomes vary greatly in N1 cohort. It has been discovered that prognostic differences exist between various patterns of N1 lymph node metastasis in previous studies. However, the absence of stations 13/14 lymph nodes data has always been an urgent problem to be solved. On the premise of complete intrapulmonary lymph node retrieval, based on the clinical experience our team had accumulated, we used subcategories within the N1 descriptor based on the location of involved N1 lymph nodes. We defined new N1a as involvement of peripheral zone lymph nodes (stations 12-14), and new N1b as involvement of hilar zone lymph nodes (stations 10-11). This new system could improve the ability to identify the heterogeneity of N1 disease. We propose that this modified classification strategy can be used as a more effective N1 descriptor.