Impact of a Ground-glass Opacity Component on c-Stage IA Lung Adenocarcinoma

Studies have shown that tumors with ground-glass opacity (GGO) components are associated with favorable outcomes. However, this view should be confirmed in an international cohort. We aimed to verify the impact of a GGO component on clinical (c)-stage IA lung adenocarcinoma and to describe the biological discrepancies between the part-solid and pure-solid groups. We evaluated 1333 cases of surgically resected c-stage IA lung adenocarcinomas, including 484 part-solid and 849 pure-solid tumors. Furthermore, we matched the solid size between the 2 groups and examined 470 patients. We compared the prognoses between the 2 groups before and after matching. The prognostic and biological differences were described before and after matching. Compared with the pure-solid group, the part-solid group was associated with favorable outcomes [5-year overall survival (OS) 99.4% vs 87.6%, P < 0.001; 5-year recurrence-free survival (RFS) 96.9% vs 82.2%, P < 0.001]. Similar results were obtained after matching (5-year OS 98.9% vs 92.2%, P = 0.012; 5-year RFS 95.0% vs 88.5%, P = 0.007). Multivariable analyses revealed that GGO component appearance was a factor of better OS and RFS. The part-solid tumor, regardless of the size of the solid component, had a similar outcome to the pure-solid tumor of c-stage T1a classification. Also, more epidermal growth factor receptor, human epidermal growth factor receptor-2 mutations, and receptor tyrosine kinase ROS-1-positive were observed in the part-solid group. In comparison, more wild types and Kirsten-Ras were observed in the pure-solid group. Adenocarcinomas with a GGO component were associated with superior outcomes. The GGO component should be considereda new clinical T descriptor. Early-stage lung adenocarcinomas with and without a GGO component may be 2 distinct tumor types.