Главная страница > Литература для специалистов > Проспективное исследование: Систематическая диссекция лимфоузлов при раке легкого с помощью видео-ассистированной торакальной хирургии: Может ли она быть совершенной?
Проспективное исследование: Систематическая диссекция лимфоузлов при раке легкого с помощью видео-ассистированной торакальной хирургии: Может ли она быть совершенной?
Ann Thorac Surg 2002;73:900
Accepted for publication October 16, 2001.
* Address reprint requests to Dr Sagawa, Department of Thoracic Surgery, Kanazawa Medical University, 1ם Daigaku, Uchinada, Ishikawa 920?, Japan
Background. There have been no reports evaluating the completeness of systematic nodal dissection with video-assisted thoracic surgery (VATS). In order to elucidate the completeness of the dissection, we have conducted a prospective trial with patients having primary lung cancer.
Methods. Patients with clinical stage I lung cancer were the candidates for this study. Thoracotomy was performed with a small skin incision of 7 cm to 8 cm in length. Through these small wounds and two trocars, pulmonary resection was performed and then hilar and mediastinal lymph nodes were dissected. After that, a standard thoracotomy was carried out by another surgeon to complete systematic nodal dissection.
Results. Video-assisted thoracic surgery lobectomy with lymph node dissection was accomplished in 17 right lung cancer patients and 12 left lung cancer patients. On the right side, the average numbers of resected lymph nodes by VATS and remnant lymph nodes were 40.3 and 1.2, respectively. The average weights of dissected tissues by VATS and remnant tissues were 10.0 g and 0.2 g, respectively. On the left side, there were 37.1 and 1.2 lymph nodes and 8.3 g and 0.2 g of weight of dissected tissues. No nodal involvement was observed in the remnant lymph nodes.
Conclusions. The lymph node dissection with VATS was technically feasible and the remnant («missed» by VATS) lymph nodes and tissues were 2% to 3%, which seems acceptable for clinical stage I lung cancer.
Many surgeons consider that thoracoscopic surgery for intrathoracic disease has some advantages over the conventional thoracotomy, including small incision, no need to sever ribs, minimal severance of muscles, less pain, reduced cytokine production, and earlier recovery of patients [1ן]. Although some potential hazards have been reported [4ע], several investigators have agreed that lobectomy by video-assisted thoracic surgery (VATS) with lymph node dissection can be an alternate for surgically treating early lung cancer [2, 7ץ]. When the procedure is considered to be surgical therapy for primary lung cancer, however, possibly less potential to cure is one of the most important concerns, especially regarding lymph node dissection because incomplete dissection may cause earlier relapse of lung cancer.
There have been no reports evaluating the completeness of systematic nodal dissection  with VATS except our preliminary report with 6 right lung cancer patients . To elucidate the completeness of the dissection and also to evaluate the actual remnant ratio of lymph nodes and tissues, we have conducted a prospective trial with patients having primary lung cancer.
The TNM classification was determined according to the Union Internationale Contre le Cancer (UICC) staging system . Histologic typing was classified according to World Health Organization (WHO) classification . Lymph nodes were numbered (1 through 13) according to lymph node mapping reported by Naruke and associates  and the American Thoracic Society .
Thoracotomy was performed with a small skin incision of 7 cm to 8 cm in length at the fifth intercostal space just below the lower angle of scapular bone for right lung cancer. Respiratory muscles and ribs were not severed except intercostal muscles. Two more trocars were placed at the fourth intercostal spaces at the anterior axillary line and the seventh or eighth intercostal spaces at the mid axillary line. For left lung cancer, the skin incision of cases 1 to 8 was the same as right lung cancer. However, the skin incision of cases 9 to 12 was changed to the fourth intercostal spaces at the anterior axillary line. The trocars were also changed to the seventh or eighth intercostal spaces at the mid axillary line and the sixth intercostal spaces at the posterior axillary line. The retractor was routinely utilized. Through these small wounds and two trocars, the designated pulmonary lobe was resected and then hilar and mediastinal lymph node dissection was performed (VATS lobectomy with lymph node dissection). The pulmonary vein and bronchus were transected with staplers and branches of the pulmonary artery were ligated and transected through the small thoracotomy wound in most cases. Usually the operation was performed approximately 50% under direct vision and 50% under videoscope.
After VATS lobectomy with lymph node dissection, a standard thoracotomy was subsequently carried out by a different surgeon to complete systematic nodal dissection. The standard thoracotomy in our institute was posterolateral thoracotomy with an approximately 15 cm skin incision at the fifth intercostal space, severing the broadest muscle of the back and the fifth or sixth rib or both. Nodal dissection was performed by dissecting soft tissues surrounding vital structures. During the VATS lobectomy, when going on with the procedure became difficult owing to possible bleeding or adhesion, conversion to the standard thoracotomy was performed.
At VATS lobectomy with lymph node dissection, the number of dissected lymph nodes and the weight of dissected tissues including fat tissue at each station were measured and recorded. In addition, the number of remnant («missed» by VATS) lymph nodes and the weight of remnant tissues of each station, found at additional thoracotomy, were measured and recorded as well. Remnant ratio was calculated both in number and in weight. Operating time required for VATS lobectomy with lymph node dissection and the amount of bleeding during the procedure were also recorded.
From June 1997 through April 2000, 19 right lung and 16 left lung cancer patients were registered. VATS lobectomy with lymph node dissection was completed in 17 of the right lung cancer patients and in 12 of the left lung cancer patients (29 of 35; 82.9%). The reasons for conversion to standard thoracotomy were severe adhesion of calcified lymph nodes to the pulmonary artery in 2 cases, severe pleural adhesion in 1 case, need for bronchoplasty in 1 case, carcinoma invasion to the pulmonary artery in 1 case, and pulmonary vascular anomaly in 1 case. Patients were 16 men and 13 women, ranging from 43 to 79 years in age (average 63.5). The characteristics of the resected cases are shown in Table 1.
Table 1. Characteristics of the Resected Patients
Table 3. Left Side: Remnant Lymph Nodes After Video-Assisted Thoracic Surgery Lobectomy With Lymph Node Dissection
Lymph node metastases were confirmed pathologically in 9 of 29 patients: case 1 (lymph node number 3), case 3 (1, 3, 12u, 12m, 13), case 6 (4), case 13 (7, 10, 11), case 15 (3, 4), case 18 (11), case 19 (11), case 22 (4, 10, 11, 12u), and case 23 (12u). Nodal involvement was not detected in the remnant lymph nodes even in pN1 and pN2 patients.
Most of the remnant nodes were very small and located at the edge of dissected area, such as lymph node 1 (highest mediastinal node), 3a (anterior mediastinal node adjacent to thymus), 3p (retrotracheal node adjacent to contralateral 3p), 7 (subcarinal node adjacent to contralateral hilar node), 8 (paraesophageal node adjacent to contralateral 8), 9 (pulmonary ligament node adjacent to diaphragm), or 3 for left side (pretracheal, deepest in the aortic arch). We consider that these small remnant nodes located at the edge of dissected area have less clinical importance, especially in clinical stage I cases. Actually no nodal involvement was observed in the remnant lymph nodes in this study, although preoperative evaluation of lymph node metastasis failed in 9 of 29 (31%) cases.
It is important that part of hilar nodes failed to be dissected in 3 cases (cases 1, 12, and 18). Two of them were the cases in the beginning of this study. In the dissection by VATS the surgical view was more limited than in the standard thoracotomy, in our experience, especially in the hilar region because the effective traction of residual lung or the appropriate change of the operators view angle (including thoracoscopic) is sometimes difficult. Careful attention must be paid not to overlook the remnant lymph nodes in the hilar region. In addition, the right number 4 node (tracheobronchial node) is also important and should be dissected with appropriate traction of the azygos vein.
There are some methodologic problems to be discussed. First, at the beginning of this study we encouraged patients with clinical T1N0M0 disease to enter the study because such patients were expected to undergo VATS lobectomy with lymph node dissection easily. Later we found this procedure was able to be applied to selected (peripheral and not so large) clinical T2N0M0 patients safely. Therefore, most of the patients in this study were T1N0M0 and the results of the present study might not be applied to the patients with large T2N0M0 lung cancers.
Second, our results show that the remnant nodes and tissues were only 2% to 3% of those that should be dissected, with a 7 to 8 cm skin incision and a retractor. Although VATS lobectomy with a smaller incision or without a retractor may have the advantages of less invasiveness and less pain, the remnant nodes in such conditions would be possibly different from our study. To resolve the problem, further study is required.
Third, in order to perform VATS lobectomy several approaches have been reported [2, 8, 9, 16, 17]. Although the axillary approach is useful in dissecting hilar structures [8, 9], the posterior approach seems to be suitable for mediastinal lymph node dissection , especially for dissecting subcarinal nodes. Therefore in the beginning of this study we chose the posterior approach for a small thoracotomy. From our experiences with the right side, the subcarinal, pretracheal, and highest mediastinal nodes were found to be easily dissected and no problem was observed in conducting this procedure through the posterior approach. In the left side, however, the descending aorta sometimes obstructs the surgical view. Therefore we switched to the axillar approach for left lung cancer, and had no problems in doing so.
In conclusion, the lymph node dissection with VATS was technically feasible, and the remnant (missed by VATS) lymph nodes and tissues were 2% to 3%, which seems acceptable for clinical stage I lung cancer. With informed consent from each patient concerning this slightly less curative potential, VATS lobectomy with lymph node dissection can be an alternate for surgical therapy of clinical stage I lung cancer patients. Prospective randomized trials will be required to evaluate the actual significance of this procedure.
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