Proposal on incorporating blood vessel invasion into the T classification parts as a practical staging system for stage I non-small cell lung cancer

Abstract

Background: We investigated blood vessel invasion (BVI) as a possible negative prognostic factor in patients with stage I non-small cell lung cancer (NSCLC) according to the 7th edition of the TNM classification.

Methods: Between 1999 and 2007, a total of 694 consecutive patients with pathological stage I NSCLC underwent complete resection with systematic lymph node dissection at Tokyo Medical University Hospital. All sections of the specimens were stained by Elastica van Gieson to visualize elastic fibers and were examined to determine the prognostic symptoms of BVI. We statistically analyzed the association between BVI and clinicopathologic factors, as well as clinical outcomes.

Results: BVI was detected in 201 patients with stage I NSCLC (29.0%). The 5-year overall survival (OS) rates of the non-BVI and BVI patients were 90.5% and 66.0%, respectively (p < 0.0001). BVI was found to be a significant independent prognostic factor by multivariate survival analysis in stage IA and stage IB NSCLC (HR 2.591, p < 0.001; HR 2.347, p = 0.009, respectively). The 5-year OS rate of patients with BVI was significantly worse than that of patients without BVI in the T1a (94.5% vs 87.5%, p < 0.0001), T1b (82.7% vs 65.9%, p < 0.0001), and T2a (90.9% vs 61.8%, p < 0.0001) subgroups.

Conclusion: We identified the presence of BVI as an independent poor prognostic factor in patients with stage I NSCLC. In the future revision of the TNM staging system, the routine use of elastic fiber stains in pathological evaluations of lung cancer for BVI determination might be recommended, and tumors with BVI should be upstaged to the higher current T staging.

Keywords: Blood vessel invasion; Elastica van Gieson stain; Non-small cell lung cancer; Prognostic factor; TNM classification; Vascular invasion.