Lung cancer is one of the commonest cancers in the world and is a significant cause of mortality. If diagnosed at an early stage, surgical resection is the mainstay of potential cure; however, few patients fulfill the relevant criteria. The role of the radiologist is integral in the multidisciplinary team for diagnosis, treatment and follow-up of patients. Central to the management of lung cancer patients is the TNM classification system, now in its seventh iteration. The aim of this article is to provide a review of the changes in the new TNM system. We also give an overview of the recent advances in imaging, including the increasing use of positron emission tomography CT (PET-CT), which is essential for the reporting radiologist.