Distinct Clinicopathologic Characteristics and Prognosis Based on the Presence of Ground Glass Opacity Component in Clinical Stage IA Lung Adenocarcinoma

Introduction: We evaluated differences in the clinicopathologic characteristics and prognosis based on the presence of ground glass opacity (GGO) components in small-sized lung adenocarcinoma. Methods: We retrospectively investigated 634 lung adenocarcinomas classed as c-stage IA in the eighth edition TNM classification. Staging was defined according to the solid component size measured by thin-section computed tomography. All tumors were grouped into either a GGO or solid group, based on the presence of a GGO component. Results: Of the cases, 215 (34%) were classed as c-stage IA1 (T1mi: 88, T1a-GGO: 102, T1a-solid: 25), 255 (40%) as c-stage IA2 (T1b-GGO: 122, T1b-solid: 133), and 164 (26%) as c-stage IA3 (T1c-GGO: 44, T1c-solid: 120). Among the 546 c-stage IA cases excluding the T1mi lesions, Cox regression analysis revealed that presence of GGO was an independently significant prognosticator (p = 0.024). The result was validated in 494 c-stage IA lung adenocarcinomas with a nonpredominant GGO component, showing the presence of GGO as a significant prognosticator (p = 0.048). When we evaluated the prognostic impact of GGOpresence in each clinical stage, the 5-year overall survival (OS) was significantly different between the GGO and solid groups (IA1: 97.8% versus 86.6%, p = 0.026; IA2: 89.3% versus 75.2%, p = 0.007; IA3: 88.5% versus 62.3%, p = 0.003). Furthermore, the 5-year overall survival b was distinct in parallel similar pathologic findings when comparing a lepidic versus an invasive component (IA1: 97.9% versus 85.6%, p = 0.031; IA2: 86.1% versus 69.4%, p = 0.007; IA3: 77.5% versus 55.8%, p < 0.001). Conclusions: Clinicopathologic and oncologic outcomes were disparate based on the presence of a GGO component in the eighth edition TNM classification of c-stage IA lung adenocarcinoma. (C) 2018 International Association for the Study of Lung Cancer. Published by Elsevier Inc. All rights reserved.