Role of systematic mediastinal dissection in N2 non-small cell lung cancer patients

The surgical results in patients with non-small cell lung cancer staged as N2 disease were historically analyzed. Twenty-six patients were confirmed to have N2 disease on the basis of histologic study of suspicious nodes without systematic mediastinal dissection (PI group), 50 patients underwent systematic mediastinal dissection (R2 group), and 17 patients had bilateral mediastinal dissection, 4 of whom were N3 positive (R3+ group) and 13, N3 negative (R3- group). The difference in the 5-year survival rate between the PI and R2 groups (8% and 16.3%, respectively) was not significant. All 4 patients in the R3+ group died of recurrence within 14 months after operation. Several findings suggest that some patients with N2 disease, especially those with three or more N2-positive stations, actually have N3 disease: The 3-year survival rate was higher in the R3- group (51.3%) compared with the R2 (32.6%; p = not significant) and PI groups (24%; p = 0.01); in the R2 group, the survival rate was significantly (p = 0.017) better for patients with N2 metastases in two stations or less than in patients with three or more N2-positive stations; and the rate of early postoperative death related to cancer correlated with the number of N2-positive stations. We conclude that accurate diagnosis of N2 and N3 disease, and therefore better evaluation of survival for patients with N2 disease, is possible by bilateral mediastinal dissection.