The 9th Edition of the <scp>UICC TNM</scp> Classification of Malignant Tumours: Updates and Rationale for Change

The standard for assessing and recording the extent of the tumour, a necessity for most malignancies, is the Tumour Node Metastases (TNM) classification. The Union for International Cancer Control (UICC) TNM committee has defined this since the early 1950s. Due to the expanding medical knowledge of tumour behaviour and advances in imaging, pathology and therapeutic options, TNM has been updated in collaboration with the American Joint Committee on Cancer (AJCC), the International Association for the study of Lung Cancer (IASLC) and the Federation Internationale de Gynecologie et d'Obstetrique (FIGO) on a regular basis. The 9th edition of the UICC TNM Classification of Malignant Tumours has recently been published. This review summarized the changes between the 8th and 9th edition. The evidence basis used for revision is described and referenced, with a focus on the changes in head and neck and lung cancers.