This international multidisciplinary classification has been produced as a collaborative effort by the International Association for the Study of Lung Cancer (IASLC), the American Thoracic Society (ATS), and the European Respiratory Society. The purpose is to provide an integrated clinical, radiologic, molecular, and pathologic approach to classification of the various types of lung adenocarcinoma that will help to define categories that have distinct clinical, radiologic, molecular, and pathologic characteristics. The goal is to identify prognostic and predictive factors and therapeutic targets.