The 7th Edition of the TNM staging system for lung cancer: what the radiologist needs to know.

Today lung cancer remains the leading cause of cancer-related death in the United States, accounting for 28% of all cases. Radiologists play an important role in the assessment of this large number of patients. Given the important role imaging plays in the care of patients with lung cancer, it is incumbent on the radiologist to have a firm understanding of the TNM (tumor-node-metastasis) staging system used to describe the distribution of disease in lung cancer. This article reviews the 7th Edition of the TNM staging system for lung cancer and important changes from the 6th Edition.