Proposal on incorporating lymphovascular invasion as a T-descriptor for stage I lung cancer

Lymphovascular invasion (LVI) and Visceral Pleural Invasion (VPI) have been reported to be risk factors for stage I Non-Small Cell Lung Cancer (NSCLC). However, only VPI was incorporated into the current 8th Tumor-Node-Metastasis (TNM) classification. This study aimed to explore the prognostic effect of LVI and VPI on TNM staging in pathological stage I NSCLC.

We retrospectively reviewed 2633 consecutive p-stage I NSCLC patients in the Shanghai Chest Hospital (2008-2012). By using the Kaplan-Meier method and Cox proportional hazard regression model, we identified the correlations between LVI, VPI, and clinical outcomes in p-stage 1 NSCLC.

Of all 2633 p-stage I NSCLC patients, 222 were pathologically diagnosed with LVI and 836 pathologically with VPI. The 5-year recurrence free survival (RFS) and overall survival (OS) rates of patients with LVI was significantly worse compared to those without LVI (61.2% vs 82.0%, p < 0.001; 73.3% vs 88.1%, p < 0.001). The same results emerged for patients with VPI (70.1% vs 85.9%, p < 0.001; 82.3% vs 90.0%, p < 0.001). Using the univariable and multivariable analysis, we found that when tumor diameter was 3 cm or smaller, LVI (RFS: hazard ratio [HR], 2.54; 95% confidence interval [CI], 1.86-3.50; p < .001; OS: HR, 2.53; 95% CI, 1.72-3.71; p < .001) and VPI (RFS: HR, 2.14; 95% CI, 1.71-2.67; p < .001; OS: HR, 1.56; 95% CI, 1.12-2.04; p = 0.01) were significant prognostic factors for RFS and OS. When tumor size was between 3-4 cm, LVI (HR, 1.84; 95% CI, 1.03-3.29; p = 0.039) and VPI (HR, 2.56; 95% CI, 1.61-4.07; p < .001) were associated with inferior OS.

The presence of LVI significantly affected OS and RFS in stage I NSCLC patients. Our results suggested that it might be better to incorporate LVI as a T descriptor as VPI in the further TNM classification.