Independent predictive value of the overall number of metastatic N1 and N2 stations in lung cancer

Abstract

Objective: The number of metastatic N2 stations is known prognostic factor in patients with non-small-cell lung cancer (NSCLC). However, involvement of N1 stations as well as that of N2 stations seems to be important in the prognosis of these patients. We therefore attempt to clarify the significance of the total number of metastatic stations in pathologic N1 and N2 NSCLCs.Methods: Patients with either pathologic N1 (n=51) or N2 (n=96) NSCL who had undergone major pulmonary resection with complete mediastinal dissection were included in this retrospective study. All positive nodes were characterized by location according to the TNM classification system. The hilar station was included with the N2 stations.Results: The total number of metastatic stations in patients with N2 disease, ranged from 1 to 8 (average 2.5), whereas that in patients with N1 disease ranged from 1 to 3 (average 1.2). The incidence of multiplestation metastasis (≥3 metastatic stations) among N2 patients (35%) was significantly higher than that among N1 patients (2%) (p<0.001). Multivariate analysis of survival showed pathologic N1 status (relative risk=0.443, p=0.013) and ≤2 metastatic stations (relative risk=0.515, p=0.020) to be significant and independent prognostic factors. Age, sex, cell type, resected lobe, and pathological T status were statistically insignificant determinates of survival.Conclusions: The total number of metastatic stations (≤2 vs≥3) is an independent prognostic indicator in patients with completely resected pathologic N1 or N2 NSCLC. The number of metastatic stations will be useful as a stratification factor in prospective clinical trials of these patients.