Mediastinal and bilateral hilar lymph nodes are the most common places where primary bronchial lung cancer is prone to lymph node metastasis, especially hilar lymph node metastasis. Once ipsilateral hilar lymph node metastasis occurs in lung cancer, it is N1; if it is bilateral hilar lymph node metastasis, especially contralateral hilar lymph node metastasis, it is N3; ipsilateral mediastinal lymph node metastasis is N2. If lung cancer has N2 or N3 lymph node metastasis, the preferred treatment is simultaneous radiotherapy and chemotherapy rather than surgery. Radical surgical resection can only be done if there is no hilar lymph node metastasis or only hilar lymph node metastasis. Once mediastinal lymph node metastasis or contralateral hilar lymph node metastasis occurs, it is locally advanced and requires neoadjuvant radiation and chemotherapy downstaging before deciding whether to do surgical treatment based on the post-downstaging evaluation.