Extent of visceral pleural invasion and the prognosis of surgically resected node‐negative non‐small cell lung cancer

BACKGROUND Visceral pleural invasion (VPI) is generally considered a poor prognostic factor in non-small cell lung cancer (NSCLC). VPI is defined as penetration beyond the elastic layer of visceral pleura (PL1), including the visceral pleural surface without the involvement of adjacent structures (PL2) by cancer cells. The aim of this study was to evaluate the influence of the extent of VPI on NSCLC prognosis. METHODS This was a retrospective study of 90 patients with resected node-negative NSCLC with VPI. The overall survival (OS) and disease-free survival (DFS) rates were estimated using the Kaplan-Meier method. Multivariate analysis for prognostic factors was performed using a Cox proportional hazards regression model. The pattern of recurrence was also compared between PL1 and PL2 groups. RESULTS Seventy-three patients had PL1. The three-year OS rates for the PL1 and PL2 groups were 97.4% and 82.4%, respectively ( P  = 0.004). The two-year DFS rates for PL1 and PL2 groups were 81.0% and 76.5%, respectively ( P  = 0.419). According to the multivariate analysis, PL2 was not a significant prognostic factor for survival outcome in node-negative NSCLC with VPI compared to PL1 (hazard ratio for DFS 1.753, 95% confidence interval 0.582-5.284; P  = 0.319). In this study, six patients in the PL1 and one in PL2 group developed ipsilateral pleural recurrence ( P  = 1.000). CONCLUSION VPI extent may not influence survival outcomes in patients with surgically resected node-negative NSCLC with VPI.