Prognostic Effect of Lymphovascular Invasion on TNM Staging in Stage I Non–Small-cell Lung Cancer

Abstract

IntroductionLymphovascular invasion (LVI) is a known adverse prognostic factor for early-stage non–small-cell lung cancer (NSCLC). Nonetheless, the prognostic effect of LVI on TNM staging of stage I NSCLC remains inconclusive. We thus hypothesized that it might be better to upstage pathologic stage IA NSCLC with LVI to pathologic stage IB NSCLC. Patients and MethodsUsing a Cox proportional hazards model, we examined the effect of LVI on disease-specific survival (DSS) in stage IA versus stage IB disease in 660 consecutive patients with stage I NSCLC (598 with adenocarcinoma, 62 with squamous cell carcinoma) who had undergone complete resection. ResultsOn univariable analysis of stage IA cases, vascular invasion (VI) was significantly associated with inferior DSS (univariable hazard ratio [HR], 3.39; 95% confidence interval [CI], 1.46-7.89; P = .005). In contrast, lymphatic invasion exhibited a tendency toward inferior DSS (univariable HR, 2.90; 95% CI, 0.97-8.66; P = .056). Multivariable analysis of DSS in stage IA cases identified VI as an independent significant prognostic factor (multivariable HR, 2.86; 95% CI, 1.58-5.18; P = .007). With VI, DSS was significantly poorer for stage IB than for stage IA patients without VI (univariable HR, 3.44; 95% CI, 1.67-7.09; P < .001). In contrast, no difference was observed between patients with stage IA and VI and stage IB patients (P = .97). ConclusionThe presence of VI independently and significantly affects DSS in patients with stage IA NSCLC. We found that stage IA with VI and stage IB disease had equivalent prognostic outcomes. Our results suggest that stage IA with VI should be upstaged to IB in the TNM classification of NSCLC.