Visceral pleural invasion impacts the prognosis of non-small cell lung cancer: A meta-analysis

Abstract

Background: In the 7th tumor, node, metastasis (TNM) classification, T1 tumors with visceral pleural invasion (VPI) are upgraded to T2a. The objective of this study was to evaluate the prognostic impact of VPI among patients with NSCLC and to propose a method of incorporating VPI into T-status classification in future staging systems.

Methods: A systematic electronic search was conducted from each database's date of inception to October 2015. The included studies were selected according to predefined inclusion criteria. The hazard ratio (HR) was used as the outcome measure for data combining.

Results: A total of 22 studies, published from 2003 to 2015, were included in this meta-analysis. In the subgroup analysis, we identified that VPI was a poor prognostic factor for tumor size ≤2 cm (2.34 [95% confidence interval (CI) 1.55-3.54; P < 0.0001]), 2-3 cm (1.81 [95% CI 1.56-2.10; P < 0.0001]), 3-5 cm (1.61 [95% CI 1.38-1.87; P < 0.0001]) and 5-7 cm (1.50 [95% CI 1.24-1.82; P < 0.0001]). In addition, we also found that there were no significant differences for the following comparisons of OS: tumor size ≤2 cm with VPI versus 3-5 cm without VPI (1.04 [95% CI 0.83-1.31; P = 0.34]); 2-3 cm with VPI versus 3-5 cm without VPI (1.04 [95% CI 0.96-1.13; P = 0.30]); 3-5 cm with VPI versus 5-7 cm without VPI (0.95 [95% CI 0.78-1.17; P = 0.66]); and 5-7 cm with VPI versus T3 status (1.03 [95% CI 0.93-1.14; P = 0.57]).

Conclusions: In addition to the current TNM classification recommendations, consideration should be given to classifying the T2a tumors with VPI as T2b and classifying T2b with VPI as T3 in the next edition of the TNM Classification for Lung cancer.

Keywords: Non-small cell lung cancer; TNM classification; Visceral pleural invasion.