Prognostic significance of the lymph node involvement around the main bronchus. The intermediate group really early N2 disease?

Introduction: N1 and N2 diseases represent heterogeneous patient groups with variable survivals. Some studies showed prognostic differences between intralobar and extralobar (hilar and interlobar) N1 disease. The prognosis of the extralobar N1 disease was similar to the single station N2 disease. Some authors designated metastases around the main bronchus as an intermediate group.

The aim of our study was to investigate the prognostic significance of intermediate group in comparison to the single station N2 disease and to skipping metastasis in relation to tumor characteristics.

Methods: From 1990 to 2007, a total of 850 patients underwent surgical resection for NSCLC: 252 (30%) had either N1 or N2 disease. We retrospectively evaluated 231 (95.8%) hospital survivors who underwent complete resection with mediastinal lymph node dissection on our institution.

Results: The 5-year survival of patients with N1 and N2 diseases was 45% vs. 37%. Survival rate did not significantly differ between intralobar vs. extralobar N1 disease or intermediate group (46%, 43% and 43%). According to N2 disease metastases in subcarinal stations and the aortic-pulmonary window showed significantly better survival than in paratracheal stations (36% and 55% vs. 24%, p=0.002). The survival associated with skipping metastasis was significantly better on the left side (50% vs. 35%, p=0.003). Adenocarcinomas were located more on the right side (19% vs. 8%, p=0.003) resulting in extended lymph node involvement.

Conclusion: The clinical significance of the intermediate group remains unclear. Their prognostic influence depends on type and extent of lymph node involvement, tumor histology and location.