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Page 2 of 14 Abe et al. Mini-invasive Surg 2023;7:28 https://dx.doi.org/10.20517/2574-1225.2023.15

Conclusion: Standardization of RAMIE may decrease the incidence of RLN palsy in patients compared to MIE.

Keywords: Robotic surgery, esophageal cancer, learning curve, recurrent laryngeal nerve palsy

INTRODUCTION
Although preoperative chemotherapy or chemoradiotherapy (CRT) followed by esophagectomy with
radical lymph node dissection has a major role in the standard treatment of resectable esophageal cancer,
radical esophagectomy is a highly-invasive procedure with high morbidity and mortality rates . Therefore,
[1-3]
the global demand for minimally invasive esophageal cancer surgery has resulted in the rapid spread of
thoracoscopic esophagectomy [minimally invasive esophagectomy (MIE)] as a minimally invasive surgical
[4]
treatment in recent years . Recently, robot-assisted MIE (RAMIE) has been introduced and rapidly
standardized for esophageal cancer surgery at various institutions in Japan. RAMIE has the advantages of
recognizing microanatomy based on 3D high-definition images, multi-joint function, and vibration
filtering, thereby improving operability, especially for superior mediastinal dissection, and enabling precise
[5-7]
surgical manipulation . However, whether the introduction of RAMIE improves patient outcomes
compared to conventional MIE is controversial.

The aim of this study was to evaluate the surgical outcomes of RAMIE compared to standardized MIE and
to determine if RAMIE improves short-term patient outcomes.

METHODS
Patients
This was a single-center retrospective cohort study. Consecutive patients who underwent MIE or RAMIE
for thoracic esophageal cancer at the Aichi Cancer Center Hospital between 2012 and 2022 were identified
from an institutional prospectively maintained database of patients with thoracic esophageal cancer who
underwent esophagectomy. The inclusion criterion for this study was thoracoscopic esophagectomy or
robot-assisted thoracoscopic esophagectomy [full minimally invasive or hybrid (laparoscopic or open
gastric mobilization) Mckeown procedure] with gastric tube reconstruction. The exclusion criteria were as
follows: patients who underwent the Mckeown esophagectomy via a right thoracotomy or mediastinoscopic
esophagectomy or those with a history of gastrectomy. MIE was introduced in our center in 2012, and MIE
has been the standard procedure for resectable esophageal cancer since 2015, when the surgical technique
was standardized. RAMIE was introduced in our center for resectable esophageal cancer in March 2019.
MIE was performed by four skilled esophageal surgeons; RAMIE was performed by two skilled esophageal
surgeons.

RAMIE and MIE operative procedures
MIE and RAMIE preparation
The patients were intubated with a single-lumen spiral tube with bilateral lung ventilation in preparation for
MIE and RAMIE. An artificial pneumothorax was established with 8 mmHg carbon dioxide gas using the
Airseal® Intelligent Flow System (ConMed, Utica, NY, USA) to secure the visual field.

A pneumothorax was initiated during MIE by puncturing the Airseal® 12-mm port using the optical view
technique at the extension of the 9th intercostal space (ICS) at the subscapular angle. This port was used as a
camera port with a 3D high-definition flexible scope. Next, five ports were inserted as follows: a 12-mm port
was inserted in the posterior axillary line of the 5th and 7th ICSs; a 5-mm port was inserted in the mid-