TNM staging system

The TNM Classification of Malignant Tumors (TNM) is a globally recognised standard for classifying the anatomical extent of the spread of malignant tumours (cancer). It has gained wide international acceptance for many solid tumor cancers, but is not applicable to leukaemia or tumors of the central nervous system. Most common tumors have their own TNM classification. The TNM staging system is sometimes referred to as the AJCC/UICC staging system or the UICC/AJCC staging system. Several revisions have been published, the latest being the ninth edition in 2025. TNM was developed and is maintained by the Union for International Cancer Control (UICC). It is also used by the American Joint Committee on Cancer (AJCC) and the International Federation of Gynecology and Obstetrics (FIGO). In 1987, the UICC and AJCC staging systems were unified into the single TNM staging system. TNM is a notation system that describes the stage of a cancer, which originates from a solid tumor, using alphanumeric codes: T (tumor) describes the size of the original (primary) tumor and whether it has invaded nearby tissue, N (node) describes nearby (regional) lymph nodes that are involved, M (metastasis) describes distant metastasis (spread of cancer from one part of the body to another). The TNM staging system for all solid tumors was devised by Pierre Denoix of the Institut Gustave Roussy between 1943 and 1952, using the size and extension of the primary tumor, its lymphatic involvement, and the presence of metastases to classify the progression of cancer.