The Number of Lymph Node Metastases as a Prognostic Factor in Patients With N1 Non-small Cell Lung Cancer

Background: Lymph node (LN) status is an important component of staging; it provides valuable prognostic information and influences treatment decisions. However, the prognostic significance of the number of positive LNs in N1 non-small cell lung cancer (NSCLC) remains unclear. In this study we evaluated whether a higher number of positive LNs results in worse survival among patients with N1 disease. Methods: The Surveillance, Epidemiology, and End Results database was used to identify 3,399 patients who underwent resection for N1 NSCLC. Subjects were categorized into groups based on the number of positive nodes: one, two to three, four to eight, and more than eight positive LNs. The prognostic significance of the number of positive LNs in relation to survival was evaluated using the Kaplan-Meier method. Stratified and Cox regression analysis were used to evaluate the relationship between the number of positive LNs and survival after adjusting for potential confounders. Results: Unadjusted survival analysis showed that a greater number of N1 LNs was associated with worse lung cancer-specific (P <.0001) and overall (P <.0001) survival. Mean lung cancer-specific survival was 8.8, 8.2, 6.0, and 3.9 years for patients with one, two to three, four to eight, and more than eight positive LNs, respectively. Stratified and adjusted analysis also showed the number of N1 LNs was an independent predictor of survival after controlling for potential confounders. Conclusion: The number of positive LNs is an independent prognostic factor of survival in patients with N1 NSCLC. This information may be used to further stratify patients with respect to risk of recurrence in order to determine postoperative management. CHEST 2011; 140(2):433-440