ABSTRACT
The status of lymph node metastasis is an important prognostic factor for many malignant tumors, including lung cancer. In the 8th edition of the TNM staging system for lung cancer, the T staging had obvious changes and refinements, but the N staging had little changes. Recently, several studies have found that the prognosis of patients with the same N stage can vary greatly, suggesting that a more detailed subgroup of patients with the same N stage should be subdivided, including the inclusion of extra-capsular lymph node metastases (ENE). In this review, we reviewed the definition, classification/grading, imaging diagnosis, pathological diagnosis, related molecular markers and their relationship with the prognosis of lung cancer patients.