Lymphatic invasion predicts survival in patients with early node-negative non-small cell lung cancer

OBJECTIVE: The aim of this study was to assess the influence of lymphatic and vascular invasion on overall survival in patients with surgically resected non-small cell lung cancer (NSCLC) without lymph node and distant metastases.

METHODS: From January 1999 to December 2009, a total of 190 NSCLC patients with node-negative pT1-pT4 disease underwent radical resection with lymphadenectomy. Pathologic reports were reclassified to the TNM-7 version, and the influence of lymphatic and vascular invasion on overall survival was examined using Kaplan-Meier and adjusted Cox proportional hazards analyses.

RESULTS: Lymphatic invasion was present in 34 (17.9%) and vascular invasion in 28 (14.7%) of 190 cases. Lymphatic and vascular invasions were correlated with higher Union for International Cancer Control stages (P = .056 and P = .011, respectively) and poor differentiated tumors (P = .051 and P = .012, respectively). There was no difference between pT1a and pT1b tumors in the presence of lymphatic (P = .912) or vascular (P = .134) invasion. Survival analyses revealed lymphatic (P < .001) and vascular (P = .008) invasion as statistically significant for the entire study population. Multivariable Cox analysis adjusted for age, Union for International Cancer Control stage, and lymphatic and vascular invasion confirmed lymphatic, but not vascular, invasion as an independent prognostic factor (P < .001; hazard ratio, 3.002; 95% confidence interval, 1.780-5.061). Especially in early stages, lymphatic invasion was associated with poorer overall survival in pT1a (P < .001), pT1b (P = .019), and pT2a (P = .028) tumors.

CONCLUSIONS: Lymphatic invasion represents an independent risk factor for node-negative NSCLC. Its implications on therapy decision making should be further evaluated, especially in early stages.