Prognostic Impact of Very Small Ground-Glass Opacity Component in Stage IA Solid Predominant Non-small Cell Lung Cancer

We evaluated the prognostic role of the presence of a very small ground glass opacity (GGO) component in stage IA solid-predominant non-small cell lung cancer (NSCLC). We evaluated surgically resected 1471 patients diagnosed with stage IA solid-predominant NSCLC. They were classified into 3 groups; that is, GGO group (0.5<CTR<0.9), Very small GGO group (0.9≤CTR<1.0), and the Solid group (CTR = 1.0). The prognostic influence of a very small GGO component was evaluated using the Cox proportional hazards model. Overall survival (OS) was estimated using the Kaplan-Meier method with a log-rank test. In total, 523 GGO groups, 91 Very small GGO groups, and 857 Solid groups were identified. The median CTR of the Very small GGO group was 0.92 ± 0.02 (range, 0.90–0.97). Both the pathological characteristics and survival outcome was similar between GGO group and Very small GGO group (5 year-OS, 91.7% Vs 89.8%, P = 0.374). However, several pathological findings including nodal involvement (8% Vs 20%, P = 0.004), lymphatic (12% Vs 27%, P = 0.003) or vascular (18% Vs 37%, P < 0.001) invasion or spread through alveolar space (9% Vs 23%, P = 0.004) were significantly different in comparison between Very small GGO and Solid group. Accordingly, the 5-year OS significantly differed between the groups (89.8% Vs 72.5%, P < 0.001), which was also demonstrated in the propensity score-matched cohort (89.4% Vs 79.2%; P = 0.019). Prognostic impact of a very small GGO component is relevant in stage IA solid-predominant NSCLC. In the future, it is necessary to confirm these data using larger multi-institutional datasets that are more appropriately powered.