Generality
Tumors are pathologies characterized by rapid and uncontrolled cell proliferation. In benign tumors this proliferation is slow and limited to the place of origin, while the cells of malignant tumors have high proliferative capacity and can invade and destroy the surrounding tissues, until they spread to other parts of the body through the bloodstream and / or the lymphatic circulation (metastasis).
Staging of a tumor is a fundamental part in the diagnosis of the disease. The prognosis of the tumor and the type of therapy that must be adopted to treat it depend on the stage of the tumor (surgery, chemotherapy, radiotherapy, immunotherapy, etc.).
TNM classification of malignant tumors
Various classification methods exist to describe the stage in which malignant tumors are found. The most used is the TNM classification system ( Tumor - Node - Metastasis ). This system was first introduced in France by Pierre Denoix, between 1943 and 1952.
The TNM classification has gained great approval internationally, but mostly applies to solid tumors. It is not applicable to widespread tumors such as leukemia and finds limited application in tumors such as diffuse lymphoma and ovarian cancer.
Each tumor has four stages, indicated - in order of increasing gravity - with the numbers I, II, III and IV . To these must be added stage 0, in the case of carcinomas in situ .
In the TNM classification each letter indicates a parameter that describes certain characteristics of the tumor:
- Letter T : indicates the size of the primary tumor. The value of this parameter varies from 1 ( small tumor ) to 4 ( large tumor ). The letter T can be flanked by the abbreviation " is " (Tis), if the tumor is in situ . If the letter T is followed by the letter " x " (Tx) it means that it is not possible to evaluate the tumor size.
- Letter N : indicates the involvement of lymph nodes in the vicinity of the tumor. The value of this parameter ranges from 0 ( no lymph node involved ) to 3 ( many lymph nodes involved ). Also in this case, if the letter N is followed by the letter " x " (Nx) it means that it is not possible to determine the quantity of lymph nodes involved.
- Letter M : indicates the presence of metastases. It can have a value of 0 ( no metastases ) or a value of 1 ( presence of metastases ).
Depending on the type of tumor and where it is located, the TNM parameters take on a different meaning: for example, T2 N0 M0 is part of stage II of breast cancer, but corresponds to stage I of lung cancer.
Furthermore, the TNM parameters can also be indicated with letters, as well as numbers. An example is that of lung cancer, in which the names M1a or M1b can be used to describe the type of metastasis: the first indicates that the metastasis is localized to the opposite lung, the second indicates that the tumor has spread to other areas of the body.
Below is an example of classification of malignant lung cancer:
| Stadium | TNM classification |
| 0 | Tis N0 M0 (the tumor is in situ ) |
| THE | T1-2 N0 M0 |
| II | T1-2 N1 M0 T3 N0 M0 |
| III | T1-2 N2-3 M0 T3 N1-3 M0 T4 N0-3 M0 |
| IV | T1-4 N0-3 M1 (when you are in the presence of any type of metastasis) |
Degree of aggressiveness of the tumor
The degree of aggression is another parameter used to have a more detailed classification of the tumor. Provides information on the degree of cellular differentiation of the neoplasm. It is indicated with the letter "G" and takes values from 1 to 4.
Grade 1 (G1) corresponds to a well-differentiated tumor, ie the cells that compose it - analyzed under a microscope - appear very different from the normal cells of the tissue from which they derive.
Grade 4 (G4) corresponds to an undifferentiated tumor, ie the cells that constitute it do not show detectable differences compared to the normal cells from which they derive.
Once again, if the letter G is followed by the letter " x " (Gx) it means that it is not possible to determine the degree of differentiation.
Well-differentiated tumors are the least aggressive, because cancer cells still possess characteristics similar to those of healthy tissue in which they have developed; vice versa, a low degree of differentiation corresponds to high aggressiveness.
Analysis to determine the stage of the tumor
To determine the stage of a tumor, the results of different analyzes are necessary:
- Symptom analysis and a careful history can provide the first indications on the position of the primary tumor;
- Laboratory tests, provide indications on how the tumor affects the normal functioning of the organism;
- Imaging diagnostics (X-rays, CT scans, magnetic resonance, etc.), allow us to determine the extent of the tumor and the presence and location of any metastasis;
- Percutaneous or endoscopic biopsies, with these techniques a part of the tissue affected by the tumor is taken and the cells that compose it are analyzed, thus allowing to identify the nature of the tumor.
