Prolonged survival in patients with resected non-small cell lung cancer and single-level N2 disease

To test the hypothesis that patients with non-small cell lung cancer and single-level N2 metastases constitute a favorable subgroup of patients with mediastinal metastases, we analyzed the results of the Eastern Cooperative Oncology Group 3590 (a randomized prospective trial of adjuvant therapy in patients with resected stages II and IIIa non-small cell lung cancer) by site of primary tumor and pattern of lymph node metastases.

Accurate staging was ensured by mandating either systematic sampling or complete dissection of the ipsilateral mediastinal lymph nodes. The overall survival of patients with left lung non-small cell lung cancer and metastases in only 1 of lymph node levels 5, 6, or 7 and right lung non-small cell lung cancer with metastases in only 1 of levels 4 or 7 was compared with that of patients with N1 disease originating in the same lobe.

The median survival of the 172 patients with single-level N2 disease was 35 months (95% confidence interval: 27-40 months) versus 65 months (95% confidence interval: 45-84 months) for the 150 patients with N1 disease (median follow-up 84 months, P =.01). However, among patients with left upper lobe tumors, survival was not significantly different between patients with N1 disease and patients with single-level N2 disease (49 vs 51 months, P =.63). The median survival of the 71 patients with single-level N2 metastases without concomitant N1 disease (skip metastases) was 59 months (95% confidence interval: 36-107 months) versus 26 months (95% confidence interval: 16-36 months) for the 145 patients with both N1 and N2 metastases (P =.001).

Survival of patients with left upper lobe non-small cell lung cancer and metastases to single-level N2 lymph nodes is not significantly different from that of patients with N1 disease. The presence of isolate N2 skip metastases is associated with improved survival when compared with patients with both N1 and N2 disease. Survival should be reported by the lobe of primary tumor and metastatic pattern to guide future clinical trial development, treatment strategies, and revisions of the TNM staging system.