The Impact of Visceral Pleural Invasion in Node-Negative Non-small Cell Lung Cancer

Visceral pleural invasion (VPI) is considered an aggressive and invasive factor in non-small cell lung cancer (NSCLC). Recent studies found that depending on tumor size, VPI influences 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. In this meta-analysis, we assessed the role of VPI in node-negative NSCLC according to various tumor sizes and especially in stage IB disease.A systematic literature search of four databases (EBSCO, PubMed, Ovid, and Springer) was performed to find relevant articles. The primary end point was 5-year overall survival. Pooled ORs were calculated using control as a reference group, and significance was determined by the Z-test.Thirteen relevant studies in 27,171 patients were included in this study. The number of patients with VPI was 5,821 (21%). VPI was a significant adverse prognostic factor in patients with tumor size ≤ 3 cm (OR, 0.71; 95% CI, 0.64-0.79; P < .001), > 3 but ≤ 5 cm (OR, 0.69; 95% CI, 0.56-0.86; P < .001), and > 5 but ≤ 7 cm (OR, 0.70; 95% CI, 0.54-0.91; P = .007). A further comparison was made with stage IB NSCLC. Tumor size ≤ 3 cm with VPI was associated with a better survival than tumor size > 3 but ≤ 5 cm regardless of VPI (OR, 1.31; 95% CI, 1.19-1.45; P < .001). Exploratory analysis found no survival benefit between tumor size ≤ 3 cm with VPI and tumor size > 3 but ≤ 5 cm without VPI (OR, 1.16; 95% CI, 0.95-1.43; P = .15); however, the prognosis for tumor size > 3 but ≤ 5 cm with VPI was not as good as that for tumor size ≤ 3 cm with VPI.VPI together with tumor size has a synergistic effect on survival in node-negative NSCLC. Patients with stage IB NSCLC and larger tumor size with VPI might be considered for adjuvant chemotherapy after surgical resection and need careful preoperative evaluation and postoperative follow-up. Further randomized clinical trials to determine the impact of adjuvant chemotherapy in patients with stage IB NSCLC with VPI are warranted.