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

Abstract

IntroductionSubcentimeter 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). MethodsWe evaluated the clinicopathological features and prognosis of 328 surgically resected clinical-N0 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]). ResultsPathological 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). ConclusionsThe 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.