According to the topographic and anatomical sign, bronchogenic cancers are usually divided into central and peripheral. This takes into account the location of the tumor in the lung and its relation to the bronchial tree.
The formation of a peripheral tumor from the bronchial epithelium of the distal, most peripheral parts of the airways — subsegmental and smaller bronchi, most often causes its uniform unhindered growth in the compliant lung parenchyma with the formation of a characteristic spherical or round formation. The adjacent tissues and lymphatic vessels of this area respond with a peculiar reaction to a growing peripheral tumor. As it develops, in the adjacent sections of the lung on the surface of the lymphatic vessels and capillaries located here, peculiar outgrowths appear and develop, directed towards the tumor and often penetrate into it. In this case, the formation of connections between the lymphatic vessels located within the tumor and the superficial capillaries and vessels of the unaffected parts of the lung. Thus, it is likely that conditions are being created for the wide penetration of cancer cells into the lymphatic channel.
Further development and growth of the tumor leads to the involvement of nearby anatomical structures in the blastomatous process: unaffected lung lobe, parietal pleura, chest wall, diaphragm, mediastinal pleura and others.
Most often, a similar spread of the tumor is accompanied by varying degrees of pronounced paracancrotic inflammatory changes. They can occur both in close proximity to the primary tumor, and in more distant parts of the lung, in the pleural cavity and in regional lymphatic collectors.
A histological study of the border areas of tumor growth in the lung showed that a rather powerful fibrous layer is initially formed around the tumor, which is later replaced by cancerous tissue. Even if the boundaries of the tumor tissue do not reach the visceral pleura for another two or three centimeters, it is noted thickening due to the growth of connective tissue, the formation of loose, and then coarser adhesions with the parietal leaf. It is assumed that the noted pleura reaction is a kind of protective against a growing tumor, a biological barrier that prevents its further spread.
Central lung cancer develops in the bronchi of a larger caliber: segmental, lobar. As a rule, this causes a violation of their patency with hypoventilation, atelectasis, and even destructive changes in the corresponding section of the lung. The latter is largely determined by the tumor growth option: mainly nodular, endobronchial or endophytic, peribronchial, perivasal — towards the surrounding bronchial structures. Then, in the first case, a violation of bronchial obstruction occurs early in connection with the closure of the airways, and in the second, a gradual decrease in their clearance until complete closure due to compression “from the outside”. Near the advanced stages of tumor development, one can often observe the so-called “centralization” of peripheral lung cancer. In these cases, a tumor that initially developed in the peripheral parts of the lung as it reaches growth reaches segmental or more often lobar, germinating it and disrupting patency.
Features of the anatomical structure of the lungs and their close topographic and anatomical relationships with the organs of the chest cavity impose peculiar features on the development of a malignant tumor here.
The location of the tumor in various lobes and even segments of the lungs with its progressive development in the form of local growth involves the nearby anatomical structures of the chest cavity and mediastinum in the blastomatous process. A detailed morphological study of the surgical material carried out in the clinic made it possible to establish, in practical terms, important patterns characteristic of lung cancer in the advanced stages of the development of the disease.