Effect of visceral pleural invasion on the prognosis of patients with lymph node negative non‐small cell lung cancer

BACKGROUND Visceral pleural invasion (VPI) is an adverse prognostic factor in non-small cell lung cancer (NSCLC); however, its effect in relation to tumor size remains under debate. To better understand the prognostic impact and potential consequences for staging, we examined correlations between VPI and clinicopathologic characteristics in patients with NSCLC, particularly those with lymph node negative NSCLC. METHODS We retrospectively analyzed 813 cases of radically resected NSCLC treated in our institution between December 2005 and December 2011. Patients were divided into two groups according to VPI status to compare their clinicopathologic characteristics. Survival analysis was performed in 521 cases with pN0 NSCLC. RESULTS VPI was diagnosed in 379 (46.6%) cases. It was more common in women, patients with non-squamous cell carcinoma, elevated preoperative serum carcinoembryonic antigen levels, moderately or poorly differentiated tumors, and larger-sized tumors. The incidence of mediastinal lymph node metastasis, particularly multi-station metastasis, was higher in patients with VPI. Patients with pN0 NSCLC, 2-3 cm tumors, and VPI had a significantly poorer prognosis (VPI vs. non-VPI: five-year overall survival 78.3% vs. 84.5%, P = 0.039; five-year disease-free survival 69.2% vs. 80.0%, P = 0.046, respectively); however, no significant effect was observed for tumors ≤2, 3-5, and 5-7 cm. P-N0 patients with VPI had a significantly higher incidence of postoperative local recurrence and distant metastasis than those without VPI (P = 0.01), especially ipsilateral pleural recurrence. CONCLUSION VPI was an adverse prognostic factor in radically resected pN0 NSCLC, especially for tumors 2-3 cm in size.