Mediastinal lymph node evaluation, especially at station 4L, in left upper lobe lung cancer

Abstract

Background: Mediastinal lymph node (LN) dissection during lung resection is essential for accurate staging. Station 4L dissection is anatomically difficult. Therefore, care should be taken to avoid complications. We investigated the importance of mediastinal LN dissection in left upper lobe lung cancer and evaluated intraoperative videos to identify relevant steps during dissection.

Methods: We retrospectively reviewed 151 consecutive patients with left upper lobe lung cancer. Finally, 139 patients were enrolled to examine the survival effects of clinical factors of metastatic LN stations. The association between risk factors or surgical procedures and recurrent laryngeal nerve palsy was analyzed.

Results: LN dissection of the left upper lobe revealed station 4L LN metastasis in nine patients, three of whom were node-negative on mediastinoscopy. Station 4L LN status was confirmed intraoperatively in 12 of 33 patients. Twenty patients had recurrent laryngeal nerve palsy, four of whom were complicated with aspiration pneumonia. Station 4L LN dissection was an independent risk factor for recurrent laryngeal nerve palsy (P=0.03). The use of an energy device near the recurrent laryngeal nerve was a significant risk factor for recurrent laryngeal nerve palsy. Incidentally, pathological N stage ≥2 was an independent prognostic factor for disease-free survival (DFS) (P=0.005) herein.

Conclusions: In patients with left upper lobe lung cancer, pathological N2 disease is an important predictor of recurrence. Therefore, accurate mediastinal LN dissection, including at station 4L, should be performed. We propose to standardize the dissection procedure at each institution to avoid complications, such as recurrent laryngeal nerve palsy.

Keywords: Lung cancer; lymph node (LN); lymph node dissection; recurrent laryngeal nerve palsy; video-assisted thoracoscopic surgery.

Figure 1

Surgical procedures for mediastinal lymph node dissection in left upper lobectomy. (A) Pleural incision along the lateral margin of the phrenic nerve (arrow head; from the superior pulmonary vein to the superior margin of the aortic arch) and identification along with en bloc resection of station 6 lymph nodes. (B) Peeling along the confirmed vagal nerve (white allow head) using scissors from the peripheral side to the bifurcation of the recurrent laryngeal nerve. (C) Peeling along the secured pulmonary artery to the ligamentum Botalli (white arrow), identification of the recurrent laryngeal nerve (black arrow head) running beside the ligamentum Botalli, and en bloc resection of station 5 lymph nodes. (D) Exposure of the tracheal wall (black arrow) by preventing damage to the recurrent laryngeal nerve and en bloc resection of lymph nodes from stations 4L to 10 along the left main bronchus.

Figure 2

Kaplan-Meier curves of (A) OS and (B) DFS according to pathological N factor. 5-year, 5-year survival; pN, pathological N; OS, overall survival; DFS, disease-free survival.