Survival of patients with resected N2 non-small-cell lung cancer: evidence for a subclassification and implications

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.

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.

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 with primary surgery, 5-year survival rates were as follows: mN2, one level involved (mN2L1, n = 244): 34%; mN2, multiple level involvement (mN2L2+, n = 78): 11%; cN2L1 (n = 118): 8%; and cN2L2+ (n = 122): 3%. When only patients with mN2L1 disease were considered, the site of lymph node involvement according to the American Thoracic Society numbering system had no prognostic significance (P =.14). Preoperative chemotherapy was associated with a better prognosis for those with cN2 (P <.0001). Five-year survival rates were 18% and 5% for cN2 patients treated with and without preoperative chemotherapy, respectively.

This study has identified homogeneous N2 NSCLC prognostic subgroups and suggests different therapeutic approaches according to the subgroup profile.