Extensive Lymph Node Dissection Around the Left Laryngeal Nerve Achieved With Robot-assisted Thoracoscopic Esophagectomy

Patients and Methods

Twenty-one consecutive patients who received RATE (RATE group) and 38 patients who received conventional TE (TE group), both with extended 2- or 3- field lymphadenectomy, for TESCC between Dec 2014 and Oct 2018 were enrolled. All patients were Eastern Cooperative Oncology Group performance status 0. To reduce heterogeneity in this cohort study, patients with synchronous double primary cancers, esophagogastric junctional cancer, or surgical reconstruction using colon or jejunum or pull-up through the subcutaneous route using a gastric tube were excluded. This study was approved by the Ethics Committee of Akita University Graduate School of Medicine (No. 1222).

RATE. All 21 patients provided informed consent to robotic surgery between Dec 2014 and Oct 2018. Ten patients who agreed to uninsured use of the da Vinci S or Si HD Surgical System underwent RATE between Dec 2014 and Mar 2018. Since Apr 2018, 11 patients have undergone esophagectomies using the da Vinci Si Surgical System in operations covered by insurance. All thoracic operations in the RATE group were performed by a consultant surgeon who had obtained the Japan Society for Endoscopic Surgery's skill qualification and the Japan Society for Esophageal Surgery's qualification. The patients were initially placed in the left lateral position under a combination of inhaled and intravenous anesthesia and a double-lumen endotracheal tube was used for single-lung ventilation (Figure 1). The right arm was raised 30 degrees cranially to expose the right axillar fossa, then tilted 15 degrees cranially and 15 degrees ventrally. Two assistant surgeons stood on the left side of the patient. The patient cart was docked 30 degrees clockwise relative to the craniocaudal axis of the patient (Figure 1). A 25-mm mini-thoracotomy was performed in the 4th intercostal space (ICS) on the anterior axillary line, carefully confirming the absence of pleural adhesion. A 12-mm trocar for the thoracoscope was inserted into the 6th ICS on the middle axillary line. Generally, another four trocars were inserted under thoracoscopic guidance: an 8-mm trocar in the 4th ICS on the posterior axillary line for the first arm of the robot, an 8-mm trocar in the 9th ICS on the posterior axillary line for the second arm, an 8-mm trocar in the 2nd or 3rd ICS on the anterior axillary line for the third arm, and a 10.5-mm trocar in the 8th ICS on the anterior axillary line for an assistant. The operator used Maryland bipolar forceps, a permanent cautery hook, monopolar curved scissors, Potts scissors, a small clip applier, a medium-large clip applier, and a large needle driver with the first arm; fenestrated bipolar forceps or Maryland bipolar forceps with the second arm; and Cadiere forceps with the third arm. We mainly used a forward-oblique viewing endoscope and often a forward-viewing endoscope.

Conventional TE. All 38 patients treated with conventional TE were operated on while in a left lateral position by five surgeons, including a surgeon consulting for insured medicine. As usual, a 25-mm mini-thoracotomy was performed in the 4th ICS on the anterior axillary line. Four 10.5-mm trocars were inserted under thoracoscopic guidance: one in the 4th ICS on the posterior axillary line for the operator's left arm, one in the 5th ICS on the middle axillary line for the scope (for an assistant surgeon), one in the 7th ICS on the posterior axillary line for the operator's right arm, one in the 8th ICS on the anterior axillary line for an assistant.

Operative procedure. The thoracic part of the operation was nearly the same in the RATE and TE groups. The operation was begun by opening the mediastinal pleura on the dissected line. The arch of the azygos vein was divided and then ligated. The right bronchial artery was generally preserved after dissecting around it, though for technical reasons this artery was not preserved in some patients in the TE group. The lymph nodes around the right RLN could be dissected below the right subclavian artery. To dissect along the left RLN, the esophagus was pulled using tape to the vent-right lateral side to separate the esophagus from the trachea and main bronchus and to enlarge the limited space so as to increase the range of movement. The thoracic duct was carefully preserved in T1-2 cancers, but was resected in T3 cancers. The pulmonary branches of the vagal nerves were preserved, and the intestinal branches were divided. For middle and lower thoracic esophageal cancers, the esophagus was divided at the level of the aortic arch by linear stapling; for upper thoracic esophageal cancers, it was divided in the supradiaphragmatic area. The lower posterior mediastinal lymph nodes were dissected from the pericardium, left pleura, descending aorta, and diaphragm.

Examination. Patients were observed for 2-48 months following surgery. We determined short-term surgical outcomes, including the number of lymph nodes dissected from the mediastinum, especially around the left RLN; the estimated blood loss during the entire surgery or during the thoracic part; and the incidence of post-operative complications, including vocal cord palsy.

Definitions. The clinical staging, including diagnosis of lymph node metastasis, was defined at a conference attended by radiologists, physicians and surgeons according to the International Union Against Cancer tumor-node-metastasis (TNM) Classification of Malignant Tumors (seventh edition) based on findings from contrast-enhanced computed tomography, esophagography, endoscopy, and systematic [¹⁸F] fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) imaging. Regional nodes were considered positive for malignancy when they were round or ovoid shaped with short axes ≥10 mm in thin-sliced computed tomography. When ultrasonography imaging pattern in the neck lymph nodes showed well-defined boundary echo, weak or sonolucent internal echo or strong with notching internal echo, we considered there was metastasis in lymph node. The operating time for the thoracic phase of the surgery was defined as the time from the start of chest incision through closure of the trocar sites in the chest. Blood loss was estimated by weighing suctioned blood and gauze pieces with absorbed blood. Following the surgery, patients were admitted to the intensive care unit (ICU) without continuing mechanical ventilation. Surgical complications were evaluated using the Clavien-Dindo (CD) classification (10). Recurrent nerve palsy, with or without vocal cord movement disorder (None or ≤CD1), was observed by bronchoscopy during admission (nearly all patients were tested on post-operative day 2).

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Figure 1.

Port design for robot-assisted thoracoscopic esophagectomy in the left lateral decubitus position and a Dicking image. 1: 1st arm; 2: 2nd arm; 3: 3rd arm; A: assistant port; PA: posterior axillary line; MA: middle axillary line; AA: anterior axillary line.

Statistical analysis. Continuous variables are presented as medians (minimum-maximum), and differences between the two groups were analyzed using the Mann-Whitney U-test. Categorized data were analyzed using the Pearson's Chi square test or Fisher's exact probability test. All statistical analyses were performed using JMP13 (SAS Institute Inc., Cary, NC, USA) and yielded two-sided p-values. Values of p<0.05 were considered statistically significant.