Indications for sublobar resection of clinical stage IA radiologic pure-solid lung adenocarcinoma

Objectives: The aim of this study was to identify clinical factors associated with lepidic growth in resected clinical stage IA radiologic pure-solid lung adenocarcinoma for identifying a possible sublobar resection candidate in the population. Methods: Clinicopathologic data were reviewed for 200 surgically resected clinical stage IA pure-solid lung adenocarcinomas. Radiologic pure-solid tumor was defined as a tumor without a ground-glass opacity component, that is, a consolidation tumor ratio equal to 1.0. Lepidic predominant adenocarcinoma included adenocarcinomas in situ, minimally invasive adenocarcinomas, and lepidic predominant invasive adenocarcinomas. Results: A total of 57 patients (29%) had lepidic predominant adenocarcinoma. The 5-year overall survival of clinical stage IA pure-solid adenocarcinoma was 83.4% and that of lepidic predominant adenocarcinoma and nonlepidic predominant adenocarcinoma was 98.1% versus 76.6%(P = .0012). A multivariate analysis revealed that maximum standardized uptake value was an independently significant variable of lepidic predominant adenocarcinoma (P <. 0001) and a significant prognostic factor (P = .034). The predictive criterion of lepidic predominant adenocarcinoma was maximum standardized uptake value 3.3 or less based on a receiver operating characteristic curve, and 77 patients (39%) who met this criterion showed less pathologic invasiveness regarding lymphatic (P = .0012) and vascular (P <. 0001) invasions, nodal metastasis (P = .0007), and better overall survival than those who did not (maximum standardized uptake value <= 3.3 vs >3.3 rates being 91.7% vs 78.6%, P = .0031). Moreover, the 3-year locoregional recurrence-free survival of the sublobar resection arm was significantly worse than that of the lobectomy arm when the tumor showed maximum standardized uptake value greater than 3.3 (62.7% vs 82.9%, P = .0281). Conclusions: Higher maximum standardized uptake value may be useful for identifying patients with clinical stage IA radiologic pure-solid lung adenocarcinoma in whom sublobar resection should not be considered, even if technically feasible.