TNM staging system
The TNM Classification of Malignant Tumors (TNM) is a globally recognised standard for classifying the extent of spread of cancer. It is a classification system of the anatomical extent of tumor cancers. It has gained wide international acceptance for many solid tumor cancers, but is not applicable to leukaemia and tumors of the central nervous system. Most common tumors have their own TNM classification. Sometimes also described as the AJCC system. 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: The TNM staging system for all solid tumors was devised by Pierre Denoix 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. General outline. The TNM classification comprises staging algorithms for almost all cancers, with the  primary exception of pediatric cancers. The general outline for the TNM classification is below. The values in parentheses give a range of what can be used for all cancer types, but not all cancers use this full range. Mandatory parameters. The Mx designation was removed from the 7th edition of the AJCC/UICC system, but referred to cancers that could not be evaluated for distant metastasis. Prefix modifiers. For the T, N and M parameters exist subclassifications for some cancer-types (e.g. T1a, Tis, N1i) UICC Stage and AJCC Prognostic Stage Groups. The TNM system is used to record the  anatomical extent of disease. It is useful to condense these categories into groups. Carcinoma in situ is categorized stage 0; often tumors localized to the organ of origin are staged as I or II depending on the extent, locally extensive spread, to regional nodes are staged as III, and those with distant metastasis staged as stage IV. However, in some tumor types stage groups do not conform to this simplified schema. The stage group is adopted with the intention that categories within each group are more or less homogeneous in respect of survival, and that the survival rates are distinctive  between groups. The Union for International Cancer Control (UICC) uses the term "Stage" to define the anatomical extent of disease. The American Joint Committee on Cancer (AJCC) uses the term "Prognostic Stage Group" which may also include additional prognostic factors in addition to anatomical extent of disease. Examples. While most Stage I tumors are curable; most Stage IV tumors are inoperable. Uses and aims. Some of the aims for adopting a global standard are to: Since the number of combinations of categories is high, combinations are grouped to stages for better analysis. Versions. The criteria used in the TNM system  have varied over time, sometimes fairly substantially, according to the different editions that AJCC and UICC have released. The dates of publication and adoption for use of the UICC and AJCC editions are summarized here; past editions are available from AJCC for web download. UICC editions: AJCC editions: As a result, a given stage may have quite a different prognosis depending on which staging edition is used, independent of any changes in diagnostic methods or treatments, an effect that has been termed "stage migration." The technologies used to assign patients to particular categories have also changed, and increasingly sensitive methods  tend to cause individual cancers to be reassigned to higher stages, making it improper to compare that cancer's prognosis to the historical expectations for that stage. A further important consideration is the effect of improving treatments over time. Essential TNM. Essential TNM is a simplified form of TNM designed specifically to enable cancer registries in low and middle income countries to collect stage information when complete details of the extent of disease are not available for collection by the registry. It is not designed to replace TNM for patient care.