Survival of Patients With Resected N2 Non–Small-Cell Lung Cancer: Evidence for a Subclassification and Implications

PURPOSE: Patients who suffer from non–small-cell lung cancer (NSCLC) with ipsilateral mediastinal lymph node involvement (N2) belong to a heterogeneous subgroup of patients. We analyzed the prognosis of patients with resected N2 NSCLC to propose homogeneous patient subgroups. PATIENTS AND METHODS: The present study comprised 702 consecutive patients from six French centers who underwent surgical resection of N2 NSCLC. Initially, two groups of patients were defined: patients with clinical N2 (cN2) and those with minimal N2 (mN2) disease were patients in whom N2 disease was and was not detected preoperatively at computed tomographic scan, respectively. RESULTS: The median duration of follow-up was 52 months (range, 18 to 120 months). A multivariate analysis using Cox regression identified four negative prognostic factors, namely, cN2 status (P < .0001), involvement of multiple lymph node levels (L2+; P < .0001), pT3 to T4 stage (P < .0001), and no preoperative chemotherapy (P < .01). For patients treated wi...