Prognostic significance of surgical-pathologic N1 lymph node involvement in non-small cell lung cancer.

BACKGROUND: Patients with N1 non-small cell lung cancer represent a heterogeneous population with varying long-term survival. To better define the importance of N1 disease and its subgroups in non-small cell lung cancer staging, we analyzed patients with N1 disease using the sixth edition and proposed seventh edition TNM classifications.

METHODS: From January 1995 to November 2006, 540 patients with N1 non-small cell lung cancer who had at least lobectomy with systematic mediastinal lymphadenectomy were analyzed retrospectively.

RESULTS: For completely resected patients, the median survival rate and 5-year survival rate were 63 months and 50.3%, respectively. The 5-year survival rates for patients with hilar N1 (station 10), interlobar (station 11), and peripheral N1 (stations 12 to 14) involvement were 39%, 51%, and 53%, respectively. Patients with hilar lymph node metastasis showed a shorter survival period than patients with peripheral lymph node involvement (p = 0.02). Patients with hilar zone N1 (stations 10 and 11) involvement tended to show poorer survival than patients with peripheral zone N1 (12 to 14) metastasis (p = 0.08). Multiple-station lymph node metastasis indicated a poorer prognosis than single-station involvement (5-year survival 39% versus 51%, respectively, p = 0.01). Patients with multiple-zone N1 involvement showed poorer survival than patients with single-zone N1 metastasis (p = 0.04). A significant survival difference was observed between N1 patients with T1a versus T1b tumors (p = 0.02). Multivariate analysis revealed that only multiple-station lymph node metastasis was predictive of poor prognosis (p = 0.05).

CONCLUSIONS: Multiple-station versus single-station N1 disease and multiple-zone versus single-zone N1 involvement indicate poorer survival rate. Patients with hilar lymph node involvement had lower survival rates than patients with peripheral N1. The impact of T factor seemed to be veiled by the heterogenous nature of N1 disease. Further studies of adjusted postoperative strategies for different N1 subgroups are warranted.