Group criteria are described in detail in Table 1. In group 5, separation occurred among pN0, pN1, and pN2 survival curves with the greater stringency of mediastinal lymph node examination requirement based on the number of mediastinal nodes. In group 6, lack of mediastinal nodal mapping stringency failed to separate pN1 and pN2 survival curves. In group 7, separation occurred among the pN0, pN1, and pN2 survival plots, but the pN1 survival was closer to the pN0 curve. In group 8, combination of the American College of Surgeons Commission on Cancer and National Comprehensive Cancer Network criteria shows the most balanced separation between the survival plots, by coupling thorough hilar and intrapulmonary lymph node examination with thorough mediastinal lymph node examination based on station mapping. + Indicates censored patients.