Prognostic significance of main bronchial lymph nodes involvement in non-small cell lung carcinoma: N1 or N2?

STUDY OBJECTIVES: Accurate TNM staging is the basis to evaluate prognosis and to plan treatment of patients with non-small cell lung cancer. Exact definition of N status is fundamental and the boundary line between N1 and N2 stations is one of the most controversial issue. Purpose of this study is to evaluate the prognostic significance of main bronchus nodes, that we classified as station number 10 (N1). METHODS: We reviewed retrospectively lymph node patterns and survival of 175 patients with N1 and 154 with N2 disease, that underwent surgical resection with hilar and mediastinal lymphadenectomy from January 1990 to December 2000. These two groups were subdivided in N1 without station number 10 involvement (N1-, n = 144), N1 with station number 10 involvement (N1+, n = 31), N2 single station (N2s, n = 107) and N2 multiple stations (N2m, n = 47), respectively. A univariate and multivariate analysis of prognostic factors predicting survival has been performed. RESULTS: Overall 5-year survival rate for 175 N1 patients and 154 N2 patients was 42 and 13%, respectively and the difference was statistically significant (P < 0.001). The prognosis between N1-, N1+, N2 was compared: 5-year survival rate was 44, 31 and 13%, respectively and the difference reached a statistical value between N1+ and N2 (P < 0.05), but not between N1- and N1+. When the comparison was made with N1-, N1+, N2s and N2m, the difference was significant between N1- and N2s (P = 0.0003), between N1+ and N2m (P = 0.0001), but not between N1+ and N2s. CONCLUSIONS: The aim of a uniform anatomical and clinical classification of nodal stations has not been thoroughly achieved, particularly regarding the boundary line between N1 and N2. Our study points out that the involvement of main bronchial nodes has a prognostic significance similar to that of N2 single station and should be considered as an early N2 disease.