New TNM staging in lung cancer (8(th) edition) and future perspectives

BACKGROUND: Carrying out a correct anatomical classification of lung cancer is crucial to take clinical and therapeutic decisions in each patient. AIM: TNM staging classification provides an accurate anatomical description about the extension of the disease; however, the anatomical burden of the disease is just one aspect that changes the prognosis. RELEVANCE FOR PATIENTS: TNM staging classification is a tool that predicts survival, but we must consider that TNM is just one of the factors that concern the prognosis. The impact of a factor over the prognosis is complex due to: It depends on the specific environment, the treatment strategy, among others, and our level of certainty makes difficult to include all the factors just in a group of stages. In some groups, there are difficulties to get large series due to the low frequency of cases and the small number of events (metastasis, locoregional recurrence). It does not allow to obtain evidence in a short period of time. On the other hand, in the next years, new markers will be incorporated in the coming years, which are going to be included in the new TNM classification. It could help to improve the classification giving more information about prognosis and risk of recurrence. All these aspects are being used by the International Association for the Study of Lung Cancer (IASLC) to develop a new prognosis model. This continues the evolution of TNM system, allows us to overcome the difficulties, and build a flexible framework enough to continue improving the individual prognosis of the patients.