Radiologic Evaluation of Small Lepidic Adenocarcinomas to Guide Decision Making in Surgical Resection

Abstract

The International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society classification of pulmonary adenocarcinomas identifies indolent lesions associated with low recurrence, superior survival, and the potential for sublobar resection. The distinction, however, is determined on the pathologic evaluation, limiting preoperative surgical planning. We sought to determine whether preoperative computed tomography (CT) characteristics could guide decisions about the extent of the pulmonary resection. We reviewed the preoperative CT scans for 136 patients identified to have adenocarcinomas with lepidic features on the final pathologic evaluation. The solid component on CT was substituted for the invasive component, and patients were radiologically classified as adenocarcinoma in situ, 3 cm or less with no solid component; minimally invasive adenocarcinoma, 3 cm or less with a solid component of 5 mm or less; or invasive adenocarcinoma, exceeding 3 cm or solid component exceeding 5 mm, or both. Analysis of variance, t test, χ(2) test, and Kaplan-Meier methods were used for analysis. The radiologic classification identified 35 adenocarcinomas in situ (26%) and 12 minimally invasive (9%) and 89 invasive adenocarcinoma (65%) lesions. At a 32-month median follow-up, patient outcomes associated with the radiologic classification were similar to the pathologic-based classification: the radiologic classification identified 14 of 16 patients with recurrent disease and all 6 who died of lung cancer. In addition, patients with radiologic adenocarcinoma in situ and minimally invasive adenocarcinoma who underwent sublobar resections had no recurrence and 100% disease-free and overall survival at 5 years. The radiologic classification of patients with lepidic adenocarcinomas is associated with similar oncologic and survival outcomes compared with the pathologic classification and may guide decision making in the approach to surgical resection.