Careful excision of the lymph nodes and tissue of the mediastinum in lung cancer presents certain technical difficulties. This is due to the complexity of the anatomical structure of the regional lymphatic system of the lungs and the nature of the topographic-anatomical relationships of individual groups of lymph nodes with surrounding organs and tissues, and they also undergo during metastasis (and sometimes without metastasis changes. Enlarged lymph nodes, merging them in various sizes, dense conglomerates, tightly welded to the elements of the root of the lung, violate the anatomical relationships, impede orientation and increase the risk of intervention. With these
It may be considered acceptable to perform combined resections of the lungs without wide mediastinal lymphadenectomy — only as a rare exception, in cases of peripheral limited lesions, in the absence of obvious signs of metastasis to the mediastinal lymph nodes, and in patients with a high degree of operational risk.
Compliance with the principle of ablastic surgery during surgical interventions for malignant tumors involves performing resection of various organs and anatomical structures within the unchanged due to blastomatous tissue damage. Only “complete” removal of all elements of the tumor allows us to hope that the operation is radical, it is a relatively reliable prevention of the development of local recurrences of the disease.
First of all, we would like to touch on the question of determining the amount of resection for the bronchus or trachea. It is directly related to the knowledge of the patterns of bronchogenic spread of lung cancer.
Local bronchogenic recurrences of lung cancer account for 15.3% of the total number of relapses of a tumor . The main cause of their development is the retention of tumor cells in the bronchus stump , which is a consequence of the intersection of the bronchus within the boundaries of the blastomatous lesion. The question of the true, microscopic boundaries of the bronchogenic spread of the tumor has repeatedly attracted the attention of researchers . From the point of view of practical surgery, it is of particular interest to study the features of the spread of tumor cells in the bronchus wall outside the visible border of tumor growth. Most authors indicate that there is a mismatch between the micro and macroscopic boundaries of tumor growth. Tumor invasion of the bronchus wall is determined to 82, 9-87% .
The data on the extent of the microscopic prevalence of tumor growth are very diverse. It is known that its boundaries are at a distance of 1.5–0 cm from the visible growth limits of the tumor , but there is evidence of the extent of tumor invasion at a distance of 3.0 or more . But 1 or 3 cm in pulmonary surgery often decides the amount of surgery, or even questions the possibility of its implementation.
Therefore, we decided to approach the study of this issue from a different position than most researchers, namely, to determine not the maximum possible extent of tumor invasion, but to identify patterns of its spread and, thus, to establish the probability of its presence at a given distance from the visible limits of growth tumors.
To study the features of the spread of blastomatous changes in the bronchus wall proximal to the visible border of tumor growth, a histological study of 54 drugs of remote lung patients operated on for central cancer was performed. Using light microscopy, a series of sections of the bronchi along the length and circumference were studied . The total number of prepared preparations is 464, the average number of histological preparations per one case is 8.6 (from 3 to 21).
According to the histological structure, 41 patients had squamous cell carcinoma (75.9%), 5 (9.3%) had adenocarcinoma, and 8 (14.8%) had undifferentiated forms of lung cancer. In 23 patients, endobronchial tumor growth was observed, in 16 patients – peribronchial, in 15 patients – mixed. Metastases to mediastinal lymph nodes were detected in 20 patients (37.0%).
The coincidence of macro- and microscopic boundaries of tumor growth was found in 25 patients (46.3%). In 18 patients (33.3%) microscopic boundaries
were 1– mm distant from macroscopic ones, 7 (13.0%) —6– mm, 2 (3.7%) —11- mm, and 1 (1.9%) —at 16 – mm and 1 (1.9%) by 21 mm. Total tumor invasion was detected in 29 patients (53.7%).
A statistical evaluation of the extent of the spread of tumor cells along the bronchus wall has been established that it obeys the exponential distribution law ( C 2 = 31.7; p <0.001) and is described as a distribution function F x = 1-exp (- L / 3.22 ) . Probability density f x = 54 exp (- L / 3.22 ) . In this study, the maximum spread of tumor cells was 21 mm, however, based on the field of definition of the exponential function (0 £ L <+ ¥ ), it follows that the maximum spread of tumor cells along the bronchus is practically unlimited, and their detection is a probabilistic process. This circumstance can also explain the contradictory literature data on the maximum length of the bronchus tumor lesion. Figure 17 presents a graph reflecting the relationship between the probability density of detecting tumor cells in the bronchus wall from the distance to the visible boundaries of tumor growth. The total number of cases studied was taken as 100% (n = 54).
It can be seen from the graph that at a distance of 5 mm the possible frequency of detection of tumor cells is 25.9%, 10 mm —13%, 15 mm —5%, and at a distance of 20 mm only 1.9%.
It has been established that there is a tendency to increase the length of tumor invasion in adenocarcinoma and undifferentiated forms of lung cancer, as well as in the presence of metastases to mediastinal lymph nodes. Although the differences were not statistically significant due to the small number of observations, we believe that they should be taken into account when deciding on the volume of resection for the bronchus or trachea.