The Impact of Visceral Pleural Invasion In Node-negative Non-small-cell Lung cancer: A Systematic Review and Meta-analysis.

Visceral pleural invasion (VPI) is considered an aggressive and invasive factor in Non-small-cell lung cancer (NSCLC). Recent studies found that VPI, dependent on tumor size, influenced T stage, but there is no consensus on whether VPI is important in node-negative NSCLC. In addition, its role in stage IB NSCLC is still uncertain. This meta-analysis sought to assess the role of VPI in node-negative NSCLC according to different tumor sizes and especially in stage IB disease.A systematic literature search was performed on four databases (EBSCO, Pubmed, OVID and Springer) to find relevant articles. The primary endpoint was 5-year overall survival. Pooled Odds ratios (ORs) were calculated using control as a reference group and significance was determined by the Z test.Thirteen relevant studies with a total of 27171 patients were included in this study. The number of patients with VPI was 5821 (21%). VPI was proved a significant adverse prognostic factor in patients with tumor size≤3cm (OR 0.71,95% CI 0.64 to 0.79; p<0.001), tumor size>3, but≤5cm (OR 0.69, 95% CI 0.56 to 0.86; p<0.001) and tumor size>5, but≤7cm (OR 0.70, 95% CI 0.54 to 0.91; p=0.007). A further comparison was made with stage IB NSCLC. Tumor size≤3cm with VPI was found to have a better survival than tumor size>3, but≤5cm regardless of VPI (OR 1.31, 95% CI 1.19 to 1.45; p<0.001). Exploratory analysis found no survival benefit between tumor size≤3cm with VPI and tumor size>3, but≤5cm without VPI (OR 1.16, 95% CI 0.95 to 1.43; p=0.15); however, the prognosis for tumor size>3, but≤5cm with VPI was not as good as the prognosis of those with tumor size≤3cm with VPI.VPI together with tumor size has a synergistic effect on survival in node-negative NSCLC. Stage IB NSCLC patients with larger tumor size with VPI might be considered for adjuvant chemo after surgical resection and need carefully preoperative evaluation and postoperative follow-up. Further randomized clinical trials that can determinate the impact of adjuvant chemo on IB patients with VPI are warranted.