Lung cancer classification during the last four decades has undergone major changes and evolution, mostly lead by pathologists who were actively involved in the International Association for the Study of Lung Cancer (IASLC) Pathology Committee. The Committee members have led the development and writing of the second (1981), third (1999 and 2004), and fourth (2015) editions of the World Health Organization classifications on lung tumors. Committee members were responsible for defining and refining the classifications of small-cell carcinoma and adenocarcinoma subtypes that are relevant to their clinical behavior.
