Mediastinal lymph node assessment is an integral component of a resection for all stages of non–small cell lung cancer (NSCLC). Debate remains as to whether there is a therapeutic benefit to complete mediastinal lymph node dissection (MLND) compared with mediastinal lymph node sampling, a question that may be answered by the American College of Surgeons Oncology Group Z0030 study. Nevertheless, there is no debate that MLND improves the staging of patients with NSCLC at the time of resection by appropriately upstaging patients without clinically obvious lymph node involvement and enabling the use of adjuvant therapy, which may improve survival.
Step 1
Surgical Anatomy
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Complete dissection of mediastinal lymph node stations is contingent on a thorough understanding of the anatomic considerations and meticulous surgical technique.
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Figure 1-1 demonstrates the most recent map of mediastinal lymph stations for lung cancer staging. ,
Figure 1-1
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The mediastinum may be subdivided into the following major regions: the right paratracheal stations ( Fig. 1-2 ), the subcarinal station accessible from either the right or left ( Fig. 1-3 ), and the left paraortic stations ( Fig. 1-4 ). After incising the mediastinal pleura, the underlying lymph node stations can be visualized.
Figure 1-2
Figure 1-3
Figure 1-4
Step 2
Preoperative Considerations
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Most patients with clinical stage I NSCLC and selected patients with stage II NSCLC are candidates for thoracoscopic lobectomy, including thoracoscopic MLND, with outcomes equivalent to conventional thoracotomy. Previous thoracic procedures are not contraindications to the thoracoscopic approach to lobectomy with MLND.
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Cervical mediastinoscopy with mediastinal lymph node biopsy should precede surgical resection and MLND in appropriate patients, including those with clinical stage IB, stage II, or stage III disease.
Step 3
Operative Steps
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After establishing single-lung ventilation with the patient in the lateral decubitus position, thoracoscopic exploration can be performed using various thoracoscopic instruments.
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Mediastinal lymphadenectomy can be performed before or after the lobectomy is completed, according to the surgeon’s preference. However, node dissection before hilar vessel dissection may facilitate the procedure.
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Node dissection can be accomplished using a combination of blunt and sharp techniques, and hemostasis can be accomplished with clips or energy sources, such as electrocautery, bipolar thermal energy, or ultrasonic devices.
1
Right Paratracheal Dissection
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Dissection of the right paratracheal lymph nodes (stations 2R and 4R) usually includes dissection of the azygos lymph nodes (station 10) and is facilitated by ligation of the azygos vein using a stapling device.
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The margins of the resection include the superior vena cava (anterior), the trachea (posterior), and the pericardium (medial). Cephalad dissection to the level of the innominate artery is performed, taking care to avoid the right recurrent laryngeal nerve. Caudally, dissection includes all lymph nodes at the hilum ( Fig. 1-5 ).
