New staging system: how does it affect our practice?

The anatomic extent of disease, as described by the TNM classification, remains the most powerful prognostic indicator for lung cancer. It is used daily by specialists in all branches of lung cancer care and research. Any new edition of the TNM classification is therefore an important event in the thoracic oncology community and one greeted with mixed feelings. The changes introduced in the seventh edition were the first for 13 years and arguably the most profound since the first data-driven revision more than 40 years earlier. Inevitably there will be concerns that any change in the T, N, or M descriptors and resultant stage groupings will have implications for previous treatment pathways. In this article, the changes to the classification are described, and their possible impacts on clinical care and research are discussed.