The role of ipsilateral mediastinal lymph node dissection in treatment of patients with non-small-cell lung cancer

Background. Lung cancer occupies the leading place in the structure of cancer incidence and death rate. Treatment results are still not satisfactory. Five-year postsurgical survival rate is 24–30%. Patients die in different periods of time from local recurrences and distant metastases. To this day, there is no unambiguous attitude towards ipsilateral mediastinal lymph node dissection in surgical treatment of patients with lung cancer. Despite the oncologic relevance of the abovementioned lymph node dissection, there are still concerns on worsening of recovery conditions of bronchial stump, increase in the amount of lymphorrhea and additional injury rate of the surgery. There is also an opinion that the risk of development of postsurgical complications, and, as a result, the increase in lethality rate, outweigh the positive impact of ipsilateral mediastinal lymph node dissection on radicality and long-term treatment results. 
Purpose – to study the impact of ipsilateral mediastinal lymph node dissection on the course of postsurgical period in patients with lung cancer, clarifying diagnostics of spread of tumor process and survival rate of the patients. 
Materials and methods. Treatment results of 187 patients with non-small-cell lung cancer with different clinical stages from T1-3N0 M0 to T1-2N1 M0 were analyzed. The patients were divided into two groups: the first group (comparison group) consisted of 72 patients, who underwent radical operations with selective lymph node dissection. The patients of the second group, the study group (115 patients), obligatorily underwent ipsilateral mediastinal lymph node dissection. The number of removed lymph nodes in one patient ranged from 5 to 10 in the first group and from 18 to 25 in the second one. In the cases when no cancer cells were found in lymph nodes, they were managed with monoclonal antibodies to cytokeratins, expressed with cancer cells, with further microscopic evaluation. During the postsurgical period the following values were studied: duration of the surgery, the volume of intraoperative blood loss, the amount and duration of exudation, frequency and character of postsurgical complications. Comparison of survival rates of the patients was performed with the test of statistical significance of differences by χ2 criterion. Methods of non-parametric statistical estimate were used for statistical analysis of the results by the means of Statistica 6.0, SPSS 17.0 software. 
Results. Adding ipsilateral mediastinal lymph node dissection to surgical interference increased its duration by 30 minutes on average. An increase in the volume of exudate by 136,2 ± 18,4 ml was observed in early postsurgical period. Structure and frequency of postsurgical complications in both groups was similar. In most cases heart rhythm disorder, namely ciliary arrhythmia, was observed in the first days after the surgery. Postsurgical lethality rate in both groups was caused by various factors and equaled 1,4% in the first, and 0,8% in the second one. Additional usage of immunohistochemicalanalysis of lymph nodes with monoclonal antibodies to tumoral cytokeratins in patients after performing ipsilateral mediastinal lymph node dissection led to their lesion being found more frequently. Indeed, metastases were detected in 21% of 19 patients, in which N0 status was previously established in light microscopy. Also, a significant increase in three-year survival rate by 15,3% (p=0,042) was observed in patients with lung cancer, who underwent ipsilateral mediastinal lymph node dissection and had no signs of mediastinal lymph nodes lesion, and 23,2% (p=0,014) in patients with the signs of the lesion. 
Conclusions. Performing ipsilateral mediastinal lymph node dissection in patients with lung cancer during surgical interference does not have an impact on postsurgical lethality rate and frequency and structure of complications. During the study of lymph nodes, which, according to light microscopy, were considered unaffected by cancer, additional lymphogland metastases were found in 20,7% of the patients by the means of monoclonal antibodies to cytokeratins. It allows the stage of the disease to be more accurately determined and optimal type of adjuvant therapy to be chosen. Detection rate of metastases in regional lymph nodes significantly increases from 51,4% to 67,8% in patients with lung cancer after radical operations with additional ipsilateral mediastinal lymph node dissection. Obligatory ipsilateral mediastinal lymph node dissection in surgeries for lung cancer increases overall three-year survival rate, especially in patients with affected lymph nodes by 16,3%.