Despite significant research advancements and the availability of numerous treatment options, lung malignancies continue to be the leading cause of cancer-related deaths worldwide, regardless of gender. Therefore, developing a universal nomenclature used to define the extent of lung cancer has been crucial for establishing individualized treatment plans for each patient. The TNM staging system is a globally acknowledged and periodically revised tool used to provide accurate clinical staging and enhance the prediction of therapy outcomes.

The ninth edition of the TNM classification of lung cancers has been implemented starting January 2025 and is based on evidence collected from a large international database, comprising 124,581 cases gathered from 25 countries.