Pure ground-glass opacity on chest computed tomography: predictive factors for invasive adenocarcinoma

Background: Pure ground-glass opacity (GGO) on computed tomography (CT) is considered a diagnostic feature of noninvasive lung adenocarcinoma. However, pure GGO can sometimes be associated with invasive adenocarcinoma (IA). The purpose of this study was to determine the predictive factors for IA when pure GGO is present. Methods: Between 2011 and 2014, 83 patients with persistent pure GGO on chest CT underwent surgical treatment for lung cancer. We compared the clinical, surgical, and pathological characteristics of non-IA with those of IA. Results: A total of 66 patients (79.5%) were diagnosed with non-IA and 17 patients (20.5%) were diagnosed with IA. The mean axial diameter of the GGO lesions in IA was larger than that in non-IA (1.9 vs. 1.2 cm; P<0.001). The incidence of pleural retraction was higher in IA than in non-IA (76.5% vs. 15.2%; P<0.001). Multivariate logistic regression analysis identified GGO lesion size and the presence of pleural retraction as significant predictive factors for IA. Conclusions: Both preoperative GGO lesion size on CT and the computed-tomography or operative finding of pleural retraction are predictive factors for IA. In patients with these findings, curative lobectomy is preferable to limited resection.