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Cancer classification
Last reviewed: 07.07.2025
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The International Union Against Cancer (UICC) TNM clinical classification of cancer is necessary to develop a methodology for the uniform presentation of clinical data. Clinical description and histological classification of cancer can play a significant role in: treatment planning; prognosis; evaluation of treatment results; exchange of information between medical centers; and promote further study of cancer. The division of tumors into groups according to so-called "stages" of the process is based on the fact that localized tumors have a higher survival rate than lesions that extend beyond the organ.
The TNM classification of cancer is based on clinical and histopathological determination of the anatomical extent of the tumor. An important task for the clinician is to determine the prognosis of the disease and plan the most effective course of treatment, which requires an objective assessment of the anatomical extent of the tumor. The TNM system meets these requirements.
[ Grouping by stages
The TNM classification of cancer provides a fairly accurate description of the anatomical spread of the disease. Four grades for T, three grades for N, and two grades for M make up the 24 TNM categories. For analysis and tabulation, these categories must be reduced to the appropriate number of stage groups.
Carcinoma in situ corresponds to stage 0. Cases with distant metastases correspond to stage IV. Stages II (A, B) and III (A, B) reflect variants of local-regional spread of the tumor process: various combinations of tumor size (T) and the degree of damage to regional lymph nodes (N).
TNM cancer classification: general rules
The TNM system, adopted to describe the anatomical extent of the lesion, is based on three components:
T (tumor) - the spread of the primary tumor; N (nodes) - the absence or presence of metastases in regional lymph nodes and the degree of their damage;
M (metastases - organ metastases) - absence or presence of distant metastases.
To these three components are added numbers indicating the degree of prevalence of the malignant process: T0, T1, T2, T3; N0, N1, N2, N3; M0, M1. In all cases, general principles are used: T - primary tumor:
Tx - it is not possible to assess the size and local spread of the primary tumor; T0 - the primary tumor is not determined; Tis - preinvasive carcinoma (carcinoma in situ); T1, T2, T3, T4 - reflects an increase in the size and/or local spread of the primary tumor; N - regional lymph nodes;
Nx - insufficient data to assess regional lymph nodes;
N0 - no regional metastases;
N1, N2, N3 - reflect different degrees of damage to regional lymph nodes by metastases; M - distant metastases;
Mx - insufficient data to determine distant metastases;
M0 - no signs of distant metastases;
M1 - there are distant metastases.