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.
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.
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 uses the term Stage to define the anatomical extent of disease. The American Joint Committee on Cancer uses the term Prognostic Stage Group which may also include additional prognostic factors in addition to anatomical extent of disease.
Examples
Small, low-grade cancer, no metastasis, no spread to regional lymph nodes, cancer completely removed, resection material seen by pathologist: pT1 pN0 M0 R0 G1; this grouping of T, N, and M would be considered Stage I.
Large, high grade cancer, with spread to regional lymph nodes and other organs, not completely removed, seen by pathologist: pT4 pN2 M1 R1 G3; this grouping of T, N, and M would be considered Stage IV.
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:
Aid medical staff in staging the tumor helping to plan the treatment.
Assist in the evaluation of the results of treatment.
Enable facilities around the world to collate information more productively.
Since the number of combinations of categories is high, combinations are grouped to stages for better analysis.
Versions
It is crucial to be aware that 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:
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.
