Prognostic Impact of the Findings on Thin-Section Computed Tomography in Patients with Subcentimeter Non-Small Cell Lung Cancer

Introduction: Subcentimeter NSCLC is not always an early-stage disease despite its small tumor size. We investigated the prognostic impact of such cancers on the basis of the findings of thin-section computed tomography (CT). Methods: We evaluated the clinicopathological features and prognosis of 328 surgically resected clinical-NO NSCLCs 1.0 cm or less in size. Consolidation-to-tumor ratio (CTR) was evaluated for all, and tumors were classified into three groups, namely, pure ground glass opacity (GGO) (CTR = 0 [n = 139]), part solid (0 < CTR < 1.0 [n = 123]), and pure solid (CTR = 1.0 [n = 66]). Results: Pathological nodal involvement was observed in seven patients, with all cases found exclusively in pure solid subcentimeter NSCLC (10.9%). Furthermore, a multivariate analysis revealed that the presence of GGO was an independently significant clinical factor in overall survival (OS) and recurrence-free survival (RFS) (OS: p = 0.0340; RFS: p = 0.0018). Histological examination revealed that 134 of the 139 cases of pure GGO (97%), 99 of the, 123 cases of part solid tumor (81%), and 16 of the 66 cases of pure solid tumor (25%) were lepidic predominant lung adenocarcinoma. Evaluation of the oncological outcomes on the basis of CTR revealed that 5-year OS and RFS rates were significantly better in patients with nonsolid tumors (OS and RFS = 100%) or part solid tumors (OS = 97.5% and RFS = 94.9%), whereas the OS and RFS rates of patients with pure solid subcentimeter NSCLC were 87.6% and 79.3%, respectively (OS: p = 0.0015; RFS: p < 0.0001). Conclusions: The findings of thin-section CT are extremely important when considering the prognosis of subcentimeter NSCLC. Radiologically determined solid subcentimeter NSCLCs should be treated as invasive tumors regardless of their small size. (C) 2017 International Association for the Study of Lung Cancer. Published by Elsevier Inc. All rights reserved.