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

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Abstract

Background. N1 disease represents a heterogeneous group of non-small cell lung carcinoma with varying 5-year survival rates. Specific types of N1 lymph node involvement need to be further investigated and their prognostic significance clarified.

Methods. From 1984 to 1993, 1,174 patients with non-small cell lung cancer had 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 reviewed. Four levels of N1 nodes were identified using the New Regional Lymph Node Classification for Lung Cancer Staging. Their prognostic significances were tested and 5-year survival rates were compared with those of N0 and N2 patients of the whole group.

Results. The overall 5-year survival rate of N1 patients was 47.5%. Survival 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 11, n = 154): 53.6% versus 38.5% (p = 0.02). Intralobar N1 5-year survival was similar to that of N0 (53.6% vs 56.5%, p = 0.01), and extralobar 5-year survival with that of N2 (38.5 vs 28.3%, p = 0.01) when N2 was present in only one station in the ipsilateral mediastinum.

Conclusions. N1 disease is a compound of two subgroups: one located inside the lobes is related to N0, and the other (extralobar or hilar) behaves like an early stage of N2 disease. This offers further information for clinical, therapeutic, and research purposes.

Section snippets

Patients and methods

From 1984 to 1993, 1,174 patients underwent pulmonary resection at Laennec Hospital and Boisguillaume Surgical Center for bronchogenic carcinoma. All patients had non-small cell carcinoma; the surgical procedure was a complete potentially curative resection with an extensive mediastinal lymph node dissection similar to that described by Martini and Flehinger [8]. Overall 5-year survival rate was 45%; “zero time” was the date of surgery and March 31, 1996 was the closing date.

Results

The cumulative postoperative survival rate at 5 years was 47.5% (Fig 1). Nine patients died within the first postoperative month, deaths resulting from surgery-related causes (3.5% of mortality rate); 10 patients were lost at follow-up (4%), 96 patients are still alive (37.5%), and 141 patients died during follow-up (55%). Cause of death was unknown in 16 patients (11.3%); not related to lung cancer in 34 (24.1%); due to another cancer in 7 (5%); and recurrence in 84 patients (59.6%).

No

Comment

The results of this study confirm that N1 disease is actually a compound of two types of lymph node involvement. This suggests that tumors with intralobar N1 extension remain a local disease and behave as N0 tumors, and that the hilar (or extralobar) N1 involvement corresponds to a lymphatic spread and has the same prognostic significance as N2 disease limited to ipsilateral single station of either upper or lower mediastinum.

This N1 classification into two groups was proposed by Naruke and

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Copyright © 1999 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.