Central tumors occupying the root zone of the lungs, in close proximity to large bronchi and blood vessels, have different relationships with the lymphatic system. Here, the lymphatic apparatus of the lungs is represented mainly by medium-sized lymphatic vessels, and the capillary network is much less pronounced. Despite the fact that the lumen of the lymphatic vessels is relatively large, the number and degree of their severity is noticeably inferior to the abundant network of lymphatic capillaries on the periphery of the lung. This is probably why direct contact of central cancers with the lymphatic channel is noticeably less and the possibility of penetration of cancer metastases into it is more limited.
A detailed study of the pathomorphological changes that occur during cancer in regional lymphatic collectors along their entire length — within the lung, mediastinum, and supraclavicular areas, carried out in the clinic showed that by the time the surgery was performed, 70% of patients already had tumor metastases. Moreover, in 48%, lymphogenous metastases reach regional collectors of the mediastinum.
The study of lymphogenous metastasis of lung cancer made it possible to reveal certain patterns of this process, which is important in practical, clinical, and surgical terms, the knowledge of which allows us to plan the implementation of surgical interventions in the most accordance with the requirements of oncological radicalism.
Metastasis of the cancer of the regional lymph nodes interferes with the normal outflow of lymph from the lobe of the lung in which the primary tumor develops. The blockade of the region of the regional collector leads first to lymphostasis, and then to the movement of lymph along the bypass, collateral, “reserve” paths within the same collector. In this case, the most common compensatory mechanism is the “opening” of those sections of the lymphatic collector that were previously in a state of functional rest. In a later period of the disease, when these pathways are also blocked by the blastomatous process, lymph drainage is carried out due to the formation of newly formed bypass lymphatic vessels. Subsequently, as pathological changes in the lung and regional lymph nodes increase, lymph outflow is ensured by the inclusion of a “reserve” from retrograde and bypass routes with its frequent drainage through the lymph nodes that are not affected, but not regional for a given lung lobe. In this case, these nodes take on a barrier function, delaying the metastases of the growing tumor.
Thus, in the initial period of the disease, lymphogenous metastases of lung cancer spread along the discharge lymphatic vessels in the most consistent with the physiological outflow of lymph. Subsequently, as the blastomatous changes progress, the process of lymphogenous metastasis proceeds more widely due to the inclusion of additional collateral vessels.
At the same time, the leading, main direction of ways to compensate for the upset lymphatic drainage occurs in the most correspondence with the direction of lymph movement through regional collectors in the area of the root of the lung and mediastinum most closely to normal conditions: from the distal to the root, mediastinum and up to the supraclavicular areas.
Following the regional lymph nodes, lung cancer metastases also affect neighboring ones, following extensive and well-defined lymphatic connections. In patients with advanced stages of lung cancer during surgical interventions, this is observed in 35% of cases. Such formation of additional pathways and directions of lymph outflow and lymphogenous metastasis from the affected lung lobes leads to the spread of metastases of cancer of the upper lobar localization in the bifurcation and even near esophageal groups of mediastinal lymph nodes.