The newly updated version of an international multidisciplinary classification of lung adenocarcinoma reflects a multidisciplinary approach to the diagnosis of this disease. The classification, intended to support clinical practice, research investigation, and clinical trials, has been revamped for the first time in 6 years by the International Association for the Study of Lung Cancer (IASLC), the American Thoracic Society, and the European Respiratory Society.

Previous classifications of lung adenocarcinoma were provided by the World Health Organization (WHO), but were always written primarily by pathologists for pathologists, according to a statement issued by IASLC, which published the current classification in its Journal of Thoracic Oncology (2011;6[2]:244-285;, accompanied by an editorial (pp. 239-240; Although the 2004 WHO classification introduced relevant genetics and clinical information, IASLC contends that the new classification is the first to be rooted in an integrated multidisciplinary platform and takes into account advances across diverse specialties in the understanding of lung adenocarcinoma. The new classification is primarily based on histology (adenocarcinoma is the most common histologic type of lung cancer) but incorporates clinical, molecular, radiologic, and surgical issues.  

William D. Travis, MD, attending thoracic pathologist at Memorial Sloan Kettering Cancer Center (New York, New York) and an author of this new classification, points out a completely new aspect of this strategy not addressed in previous WHO incarnations: a section dedicated to the diagnosis and classification of non-small cell carcinoma in small biopsies and cytology. “This is important because 70% of lung cancers present in advanced stages,” explained Dr. Travis in the IASLC statement.

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Another key new recommendation is that epidermal growth factor receptor (EGFR) mutation testing should be performed for patients with advanced lung adenocarcinoma, due to the predictive benefit in response rate and progression-free survival for mutation-positive patients who are treated with tyrosine kinase inhibitors.