Accounting, systematization, assistance and assessment of its results in lung cancer have identified the need to develop classification criteria for the disease, which would take into account its main signs and manifestations, the nature and prevalence of pathological changes.
Over the past few decades, for this purpose, they are universally guided by the classification adopted by the International Cancer Union under the TNM system and known in our country — the clinical classification of lung cancer.
In accordance with these mutually complementary classifications, all patients with lung cancer can be divided into four groups, each of which is respectively designated as stage I, II, III and IV of the disease.
As we deepen and refine our knowledge of malignant tumors, improve the methods of treatment for such patients, the classification features of each stage are periodically supplemented, corrected, or necessary clarifications are made. The latest, 4th edition of the International Classification (1989) currently most fully reflects the achievements of scientific research in oncology, makes it possible to evaluate and compare the results of the work carried out in research and medical institutions of our country and with great reliability abroad.
Moreover, each of the conventions adopted in the TNM system is given a clinical and morphological interpretation, which makes it possible to characterize the prevalence of certain changes in a digital image (from 0 to 4). Their combination receives expression in the form of a designation of a particular clinical stage of the disease.
Symbol “T” characterizes the features of the development of a primary cancerous tumor in the lung.
T 1 – a tumor of no more than 3 cm in the largest dimension, surrounded by lung tissue or visceral pleura, without visible invasion proximal to the corresponding lobar bronchus.
T 2 – a tumor of more than 3 cm in the largest dimension or of any size, but germinating visceral pleura or accompanied by atelectasis, obstructive pneumonia, and also extending to the root of the lung. The edge of the tumor is located more than 2 cm from the bifurcation of the trachea.
T 3 is a tumor of any size that directly goes to the extrapulmonary anatomical structures of the chest cavity: the chest wall, diaphragm, mediastinal pleura, pericardium, as well as a tumor that is less than 2 cm from the trachea bifurcation, or which causes atelectasis and obstructive pneumonia of the entire lung.
T 4 – a tumor of any size that directly passes to the mediastinal organs: heart, large vessels, esophagus, trachea, as well as vertebral bodies, bifurcation of the trachea or accompanied by a malignant pleural effusion.
For lymph nodes — regional and more distant lung collectors, the value of the “N” symbol, first of all, suggests the presence or absence of damage to them with cancer metastases.
N 0 – metastases in the lymph nodes are absent. N 1 – metastases affect the lymph nodes of the intrapulmonary region of the regional lymphatic collector: bronchopulmonary, root.
N 2 – lymph nodes of the mediastinal region of the regional lymphatic collector are affected by metastases within the side of the lung affected by the tumor.
N 3 – lymph nodes of the mediastinal section of the lymphatic collector are affected by metastases on the lesion side of the lung tumor and the opposite side. There are metastases in the lymph nodes of the supraclavicular areas.
It should be noted that at present, for the supraclavicular departments of regional lymphatic collectors of the lungs, it is more correct to separate the lesions with metastases separately from the ipsi and contralateral lymph nodes, by analogy with mediastinal lymphatic collectors. The spread of metastases in the lung ipsilateral to the tumor in the mediastinal collectors to the supraclavicular region is not always evidence of complete disorganization
lymph outflow and the process goes beyond the regional lymph nodes to the lung.
The symbol “M” characterizes the absence of —M 0 or the presence of distant hematogenous metastases in internal organs or other anatomical structures. Apparently here in the near future there will also be a need to isolate multiple and single, solitary, hematogenous metastases , accessible to effective therapeutic effects.