Prognostic significance of surgical-pathologic N1 disease in non-small cell carcinoma of the lung

Background. N1 disease represents a heterogeneous group of non-small cell l ung carcinoma with varying 5-year survival rates. Specific types of N1 lymp h node involvement need to be further investigated and their prognostic sig nificance clarified. Methods. From 1984 to 1993, 1,174 patients with nonsmall cell lung cancer h ad complete mediastinal lymph node dissection: N0, 50.25% (n = 590); N1, 21 .8% (n = 256); and N2, 27.95% (n = 328). The N1 subgroup cases were reviewe d. Four levels of N1 nodes were identified using the New Regional Lymph Nod e Classification for Lung Cancer Staging. Their prognostic significances we re tested and 5-year survival rates were compared with those ofN0and N2 pat ients of the whole group. Results. The overall 5-year survival rate of N1 patients was 47.5%. Surviva l was not related to site of the primary lung cancer, pathologic T factor, histologic type, type of resection, number of N1 station involved, nor type of N1 involvement (direct extension or metastases). Five-year survival was significantly better when N1 involvement was intralobar (levels 12 and 13, n = 102), as compared with extralobar (hilar) involvement (levels 10 and 1 1, n = 154): 53.6% versus 38.5% (p = 0.02). Intralobar N1 5-year survival w as similar to that ofN0(53.6% vs 56.5%, p = 0.01), and extralobar 5-year su rvival with that of N2 (38.5 vs 28.3%, p = 0.01) when N2 was present in onl y one station in the ipsilateral mediastinum. Conclusions. N1 disease is a compound of two subgroups: one located inside the lobes is related to NO, and the other (extralobar or hilar) behaves lik e an early stage of N2 disease. This offers further information for clinica l, therapeutic, and research purposes. (C) 1999 by The Society of Thoracic Surgeons.