Border between N1 and N2 stations in lung carcinoma: Lessons from lymph node metastatic patterns of lower lobe tumors

N1 and N2 diseases appeared as a combination of subgroups: intralobar N1 disease, hilar N1 disease, lower mediastinal N2 disease, and upper mediastinal N2 disease. Interestingly, the survivals of patients with involvement up to interlobar nodes (station 11), main bronchus nodes (station 10), and subcarinal nodes (station 7) were identical. These data constitute the basis for a larger investigation to develop a lymph node map in lung cancer.