Objective: To investigate the relationship between the metastatic lymph node ratio (LNR) and the prognosis of non-small cell lung cancer (NSCLC).
Methods: A total of 301 patients with N1 and N2 NSCLC undergoing curative pulmonectomy were analyzed retrospectively. There were 103 females and 198 males with a median age of 59 years (range: 31 - 78). The correlations between LNR and clinicopathological data were analyzed by χ(2) test. The effects of LNR on overall survival (OS) and disease free survival (DFS) of patients were analyzed by the methods of univariate Kaplan-Meier and multivariate Cox proportional hazard model. The risk groups were classified by LNR on the basis of N staging.
Results: LNR correlated with age, smoking status, pathological type, clinical stage and N stage (P < 0.05). And it also correlated with positive lymph nodes, resected lymph nodes and the number of positive lymph node station (P < 0.001). Kaplan-Meier survival analysis revealed that LNR influenced significantly the lengths of OS (P < 0.001) and DFS (P < 0.001). Cox proportional hazard model showed a high LNR was an independent poor prognostic factor for OS (HR = 2.507, 95%CI 1.612 - 3.900, P < 0.001) and DFS (HR = 1.872, 95%CI 1.182 - 2.964, P = 0.008); and at the same N stage, the low-LNR group was better in OS and DFS than the high-LNR group. After stratification into high-, medium- and low-risk groups, the high- (LNR: > 18%, N-status: N2), intermediate- (LNR: > 18%, N-status: N1; LNR: < 18%, N-status: N2) and low-risk factors (LNR: < 18%, N-status: N1) could efficiently predict the outcomes. The 5-year survival rate (32.8% vs 20.7% vs 6.9%), median survival time (MST) (57 vs 30 vs 16 months), 5-year disease-free survival rate (28.1% vs 16.3% vs 5.5%) and disease-free survival time (38 vs 19 vs 10 months) decreased progressively with the rising risk groups (P < 0.001).
Conclusion: LNR may be used to accurately predict the prognosis, guide the treatment of NSCLC and improve its staging.