Background: Lymphatic permeation (ly) has been described as a potential prognostic factor for non-small cell lung cancer (NSCLC).
Methods: The purpose of this study was to analyze whether evaluation of the presence or absence of ly and its location (ly 0: absent, N=464; ly 1: intratumoral, N=42; ly 2: extratumoral, N=52) provides an appropriate means of predicting the outcome of NSCLC. We investigated the clinical implications of ly in 558 consecutive patients with surgically resected NSCLC.
Results: Evaluation according to ly status showed that the recurrence-free survival (RFS) time of the ly 2 patients was significantly shorter than that of the ly 0 patients (P<0.0001), the ly 1 patients (P=0.0028). A significant difference in RFS time was also observed between the ly 0 patients and the ly 1 patients (P=0.0025). RFS time of the ly 0 patients was significantly longer than that of the ly 1 plus ly 2 patients (P<0.0001). We also evaluated the patients with pathological stage I disease (N=378) separately. The RFS time of the ly 2 patients (N=9) was significantly shorter than that of the ly 0 plus ly 1 patients (P<0.0001). In the nine ly 2 patients, six developed a distant metastasis within 1 year. A multivariate analysis revealed that ly status (ly 0 plus ly 1 versus ly 2) was an independent prognostic factor (P=0.0116), demonstrating the significant prognostic value of extratumoral lymphatic permeation in NSCLC.
Conclusions: These results indicate that ly status is a good prognostic marker of poorer outcome in patients with resected NSCLC.