For patients with lung cancer in the advanced stages of the development of the disease, it turned out to be practically expedient to subdivide into stages IIIA and IIIB. This is determined by the peculiarity of the resulting pathomorphological changes.

A common, most characteristic sign for the advanced stages of the disease III is the exit of a blastomatous lesion beyond the affected lung. Moreover, for III Astadia, the spread of lymphogenous metastases to the mediastinal departments of regional collectors is predominant. In stage III of the disease, the growth and transition of the primary tumor to extrapulmonary anatomical structures of the chest cavity and mediastinum is more characteristic: the chest wall, diaphragm, mediastinal pleura, pericardium, esophagus, superior vena cava, etc. In this case, the difference between stage IIIB and stage IV lung cancer is limited. the locality of this type of lesion, when in a specialized hospital, when performing surgical interventions, their sufficient oncological radicalism can be ensured.

It should be noted that a clear separation of the group of patients attributable to stage III of the development of the disease, until recently, has been a difficult task. Individual manifestations and signs of tumor growth, characterizing the exit of a blastomatous lesion beyond the lung, can be very similar to stage IV, especially when it comes to surgical treatment. Then, their differences in prevalence and extent in many cases can be established only after a thoracotomy and an urgent histological examination, sometimes repeatedly.

For the same reason, the establishment of the stage of lung cancer for patients who undergo surgical treatment is decided only after a thorough, most often, using the method of serial histological examination. This gives grounds to determine with the greatest accuracy the degree of blastomatous lesion, and when analyzing the results of the treatment, be guided by the classification features of the International Classification according to the TNM system with the qualifying symbol “p”.

Until recently, it was very difficult to classify patients with lung cancer in the far advanced stage IV of the development of the disease, characterized by the defeat of a single, solitary metastasis of one of the internal organs, when resolving issues of medical and especially surgical tactics. The information accumulated to date convinces us that in such cases, radical surgical intervention on the lung and surgical removal of solitary hematogenous metastasis provide prolongation of life and even many years of fruitful life of some patients.

Lung cancer with primary multiple lesions by tumors of other internal organs has not yet been classified in detail due to the relatively small number of such observations. In practical work for this category of patients, it is advisable to be guided by the International and clinical classifications with the definition of the stage of the disease according to the accepted criteria for each of the diagnosed tumors.