The involvement in the blastomatous process of ever new groups of lymph nodes due to the defeat of their cancer metastases more and more complicates the outflow of lymph from the lung. The mechanical and functional insufficiency of the lymphatic outflow developing in the late period leads to the formation of new, bypassing lymphatic vessels, and lymphatic pathways.
The formation of newly formed lymphatic vessels naturally occurs much more slowly than the opening of bypass collaterals due to previously functionally inactive sections of the lymphatic collectors. The developing mechanical insufficiency of the lymphatic outflow leads to noticeable disturbances in the clearly oriented, regional lymphatic flow from the lung affected by the tumor. Cancer metastases begin to spread more spatially across the lymphatic collectors.
In the terminal period of the development of the disease, transverse lymphatic vessels connecting the collectors of the right and left sides of the mediastinum are included in the lymphatic flow. Then the lymph from the affected lung enters the lymph nodes of the opposite side of the mediastinum, introducing cancer metastases into them.
Blockade by metastases of regional lymph nodes, lymphostasis, and especially – retrograde lymphatic flow, lead to an unusual spread of the tumor. Such
retrograde metastasis can occur in any department during a regional lymphatic collector — within the lung, in the area of its root, in the mediastinum, and in the supraclavicular regions. With a retrograde lymphatic current, involvement of the lymph nodes of the lobe adjacent to the affected tumor is possible in the blastomatous process, but this is quite rare.
The most common and regular is the metastasis of cancer along intrapulmonary collectors in the most accordance with the normal movement of lymph along the discharge vessels from the tumor-affected lobe. Deviations here are possible only with blockade by metastases, not so much of groups of intrapulmonary lymph nodes, as of higher-lying — root and, especially, mediastinal. It is with blockade of the lymphatic collector at this level that retrograde lymphatic flow and retrograde metastasis occur most constantly.
With extensive metastasis of lung cancer to the lymph nodes of the mediastinum, the occurrence of retrograde lymph flow in the top-down direction can lead to damage to the retroperitoneal lymph nodes. However, the high plasticity of the lymphatic system and its extensive network within the mediastinum make low the likelihood of such a spread of lung cancer metastases. As a rule, such findings are rarely found in the pathoanatomical study of people who died from the progression of the disease without surgical treatment.
The variety of changes that occur with lymphogenous metastasis of lung cancer, nevertheless, makes it possible to highlight the most naturally manifesting basic features of this process. Among the clinically and surgically important are the following.
The spread of lymphogenous metastases of lung cancer to regional lymphatic collectors occurs sequentially. Initially, the intrapulmonary groups of the lymph nodes are affected, then the root groups, then the mediastinal and, finally, supraclavicular. Such a staged nature of metastasis was observed in the vast majority of patients operated in the clinic. Only in a few observations, metastases of intrapulmonary and mediastinal nodes with intact lymph nodes of the root group were affected. Metastases in the lymph nodes of the mediastinum with intact pulmonary and root metodases were even less common.
Similar metastasis options have been observed by other researchers. Daument (1963) called it “galloping.” The anatomical basis for such a spread of metastases is direct lymphatic connections between the regions of the common regional collector that are far removed from each other. Meeting infrequently, nevertheless, this option of metastasis is of some importance in planning surgical interventions for cancer in compliance with the principle of regional metastasis and fully justifies the need for a wide revision of the lymphatic collectors of the mediastinum, even with unchanged or uninfected lymph nodes of the intrapulmonary and root groups.