Hilar lymph nodes in N2 disease: Survival analysis of patients with non-small cell lung cancers and regional lymph node metastasis

Purpose. This study was conducted to accurately define the N status of non-small cell lung carcinoma (NSCLC). Methods. We retrospectively reviewed 147 patients with NSCLC and pathologically positive regional lymph nodes who underwent major pulmonary resections with complete mediastinal lymph node dissections. Results. The overall 5-year survival rate was 41% after a median follow-up period of 33 months. The survival rate of patients with hilar N1 disease (26%) was significantly lower (P = 0.002) than that of those with interlobar and intrapulmonary N1 disease (60%). The survival rate of patients with hilar N1 disease (26%) was similar to that of those with N2 disease (33%; P = 0.56). Cox proportional hazards analysis with the covariates of age, sex, cell type, site of resection, pathological T factor, and pathological N factor revealed that pathological N factor indicated a relative risk for N2 disease of 1.76 (P = 0.028). Grouping hilar N1 disease with N2 disease showed that the relative risk of this "new N2 disease" with the same covariates was 2.65 (P = 0.002). Conclusion. According to our data, hilar N1 disease should be grouped with N2 disease because this combined category accurately reflects surgical outcome.