Lymphatic invasion is a more significant prognostic factor than visceral pleural invasion in non-small cell lung cancer with tumours of 3 cm or less

Background and objective: Visceral pleural invasion is an upstaging factor that increases cancer staging from stage IA to IB for tumours of 3 cm or less. However, lymphatic invasion has not been associated with the tumour–node–metastasis (TNM) staging system. The purpose of this study was to compare visceral pleural invasion and lymphatic invasion as prognostic factors. Methods: We retrospectively reviewed 353 consecutive patients who underwent curative resection for stage I non-small cell lung cancer (NSCLC) tumours of 3 cm or less. Patients were divided into three groups and compared. Group A contained no invasions; group B contained visceral pleural invasion only and group C had lymphatic invasion only. Results: Group A patients had stage IA, but group B patients had stage IB tumours. However, group C patients had stage IA tumours. The 5-year recurrence-free survival for the three groups was 86.2%, 71.5% and 48.0%, respectively. There was a significant difference in survival between groups A and C (P = 0.001).Survival was not different between groups A and B (P = 0.547). In a multivariate analysis conducted to determine risk factors for recurrence, lymphatic invasion was a significant independent risk factor for recurrence (hazard ratio = 2.570, P = 0.006). Pleural invasion was not a significant risk factor for recurrence. Conclusion: Lymphatic invasion is a more significant prognostic factor than visceral pleural invasion in NSCLC of 3 cm or less.