Objective Intratumoral vascular invasion (IVI) in patients with non-small cell lung cancer (NSCLC) has been reported to be a strong independent predictor of recurrence, but it has not been incorporated in the TNM classifications including the latest 7th edition. The purpose of this study was to evaluate its significance as a risk factor for recurrence.

Methods Between July 1992 and December 2006, 2295 consecutive patients with pathological T1–4N0–2 NSCLC underwent complete resection with systematic lymph node dissection at the National Cancer Center Hospital East. The recurrence-free proportion was estimated using the Kaplan–Meier method and differences were determined by the log rank test. Cox proportional hazard ratios were used to identify independent risk factors for recurrence.

Results The proportion of recurrence-free patients at 5 years was 85.0% for patients without IVI and 51.5% for patients with IVI (p<0.001). On multivariate analyses, IVI proved to be an independently statistically significant risk factor for recurrence (HR 1.866, p<0.001). The recurrence-free proportion of patients with IVI was significantly lower than for patients without IVI in T1a (93.1% vs 69.3%, p<0.001), T1b (89.7% vs 62.7%, p<0.001), T2a (78.4% vs 53.0%, p<0.001), T2b (70.5% vs 46.4%, p=0.021) and T3 (53.1% vs 37.4%, p=0.031) subgroups.

Conclusions In resected patients with T1–4N0–2 NSCLC, IVI was an independently significant risk factor for recurrence. IVI should be examined and its data collected to be considered for the next revision of the TNM staging system.